Traditional Herbal Medicine: A Potential Therapeutic Approach for Adjuvant Treatment of Non-small Cell Lung Cancer in the Future

Abstract

Lung carcinoma is the primary reason for cancer-associated mortality, and it exhibits the highest mortality and incidence in developed and developing countries. Non-small cell lung cancer (NSCLC) and SCLC are the 2 main types of lung cancer, with NSCLC contributing to 85% of all lung carcinoma cases. Conventional treatment mainly involves surgery, chemoradiotherapy, and immunotherapy, but has a dismal prognosis for many patients. Therefore, identifying an effective adjuvant therapy is urgent. Historically, traditional herbal medicine has been an essential part of complementary and alternative medicine, due to its numerous targets, few side effects and substantial therapeutic benefits. In China and other East Asian countries, traditional herbal medicine is increasingly popular, and is highly accepted by patients as a clinical adjuvant therapy. Numerous studies have reported that herbal extracts and prescription medications are effective at combating tumors. It emphasizes that, by mainly regulating the P13K/AKT signaling pathway, the Wnt signaling pathway, and the NF-κB signaling pathway, herbal medicine induces apoptosis and inhibits the proliferation and migration of tumor cells. The present review discusses the anti-NSCLC mechanisms of herbal medicines and provides options for future adjuvant therapy in patients with NSCLC.

Introduction

Lung cancer is the primary cancer-associated cause of mortality and constitutes a major public health concern around the globe.^1,2 Non-small cell lung cancer (NSCLC) comprises ~85% of lung cancer cases, and the 5-year survival rate for patients with advanced NSCLC is only 15%.^3,4 In the last 20 years, conventional therapies for NSCLC have included surgical resection, radio-chemotherapy, and immunotherapy. ⁵ Surgical removal is the primary medical intervention for patients with early-stage NSCLC; however, >81% of clinically diagnosed patients with NSCLC are not candidates for surgery. ⁶ For advanced NSCLC, platinum-based chemotherapy is the first-line choice of medication, but the prognosis remains unsatisfactory.^7,8 Radio-chemotherapy often causes adverse effects in clinical practice, and drug resistance is prone to develop. These side effects may exacerbate the condition in certain patients with lung cancer and have unintended consequences. Immunotherapy is not yet commonly used in clinical practice and is expensive.^5,9 With the remarkable improvement of disease screening and diagnosis technology, targeted therapy and immunotherapy have gradually emerged in recent years. Many targeted drugs and immune checkpoint inhibitors have been approved by FDA and used in the clinic,^10-19 but with many toxic side effects including rash, diarrhea, nausea, and even nervous/cardiac system disorders (Table 1). Therefore, finding effective therapies remains a serious challenge.^8,20 Traditional Chinese herbal medicine dates back thousands of years and is a subset of traditional Chinese medicine. Recently, Chinese herbal medicine has become a widespread topic, and researchers are currently using scientific approaches to elucidate its mechanism, safety, and effectiveness. During the COVID-19 epidemic, about 90% of COVID-19 patients in China have received TCM treatment. The clinical efficiency is as high as 80% and it has nearly no toxic side effects. ²¹ Researchers have summarized numerous herbs or their derivatives with potential preventive and therapeutic effects on anti-COVID-19, such as Jinhua Qinggan granules, Xuebijing, Pudilan Xiaoyan Oral Liquid, and so on. ²² As an auxiliary and complementary medicine in China, traditional herbal medicine is prevalently used in clinical practice.^23,24 Traditional herbal medicine has the advantages of alleviating clinical symptoms, enhancing autoimmunity and helping to manage the quality of life of patients.^25-27 Previous studies have reported that herbal extracts and prescriptions through multi-targeting inhibit tumor proliferation, induce tumor apoptosis, and alleviate drug resistance.^28-30 The present review focuses on recent developments in using herbal medicine to treat NSCLC and may offer a potential adjuvant treatment option.

Table 1.

Summary of Targeted and Immunotherapeutic Agents in Non-small Cell Lung Cancer.

Drug	Phase	Primary outcome	Adverse effects	(Refs.)
Gefitinib	III	PFS10.8 month;OS 30.5 month;	Rash/neutropenia/anemia/appetite loss/sensory neuropathy	Maemondo et al 10
Ceritininb	II	ORR62%; PFS 9.3 months; OS 24 month	Diarrhea/Nausea/Anorexia	Lim et al 11
Dabrafenib	II	ORR 54%;	Decreased appetite/fatigue/asthenia/dyspnea/nausea	Planchard et al 12
Osimertinib	III	PFS18.9 month; ORR 80%; Median overall survival 17.2 month	Rash/Acne/ Diarrhea/dry skin	Soria et al 13
Entrectinib	II	ORR 78%	weight increase/neutropenia, nervous/cardiac system disorders	Drilon et al 14
Pembrolizumab	I	ORR19.4%; Median overall survival 16.2 month; PFS 3.7 months; OS 12.0 month	Pneumonitis/Fatigue/colitis	Garon et al 15
Atezolizumab	III	OS: 20.2	Asthenia/Fatigue	Spigel et al 16
Ipilimumab + nivolumab	III	ORR 22%; SD 33%	Respiratory failure/bronchopulmonary hemorrhage/toxic epidermal necrolysis	Antonia et al 17
pembrolizumab + pemetrexed carboplatin (PC)	II	ORR 56.7%; PFS 24.0 month;	Fatigue/Nausea/Anemia	Borghaei et al 18
Pembrolizumab + stereotactic body radiotherapy	II	ORR 12 week; PFS 6.6 month; OS 15.9 months	Immune-related adverse event/Nephritis	Theelen et al 19

Abbreviations: PFS, progression-free survival; Bcl-2, Associated X Protein; ORR, Objective Response Rate; OS, overall survival; SD, stable disease.

Herbal Medicine Extracts Commonly Used in NSCLC Treatment

The identification of novel drugs against neoplasms is important for cancer treatment. Numerous observations indicate that herbal medicine may exert anticancer effects via various mechanisms, including modulating cancer-related signaling pathways, suppressing cell proliferation, and causing apoptosis and autophagy. Herbal medicine extracts help to treat various malignancies.^31,32 The following herbal extracts are examples of their effects against NSCLC (Table 2).

Table 2.

Effects of Herbal Extracts on Non-small Cell Lung Cancer.

Herbal extract	Plant	Cell line; In vivo model	Mechanism	(Refs.)
Thevebioside	Thevetia peruviana (Pers) K. Schum.	A549/H460; orthotopic mice	Inactive PI3K-AKT signaling pathway	Yao et al 34
Thymol	Ocimum gratissimum L. and Satureja thymbra L.	A549, KLN205	Arrest the cell cycle Induce apoptosis	Balan et al 53 , Elbe et al 54 , Koparal and Zeytinoglu 55
Ginsenoside Rg3	Ginseng	A549/HCC827; A549/DDP PC9; C57BL/6 mice	Activate VRK1/P53 pathway; relieve drug resistance	Zhang et al 60 , Poon et al 61 , Liu et al 64 , Tan et al 67 , Jiang et al 68 , Wang et al 69
Cinnamaldehyde	Cinnamomum cassia	A549/YTMLC-90/H1299/ H460; BALB/c nude mice	Suppress Wnt/β-catenin signaling Downregulate; MMP-2 and MMP-9; Arrest the cell cycle	Wu et al 73 , Tian et al 74 , Hong et al 75 , Park and Baek 76
Sesamin	Sesamum indicum	A549/H1792; BALB/nude mice	Regulate AKT/P53 signaling pathway Increase ROS	Chen et al 42 , Fang et al 43 , Yang et al 44
Eupatolide	Inula helenium	A549/H1975; BALB/C mice	Inhibit STAT3 signaling pathway	Ma et al 80
Piperlongumine	Piper longum L.	A549/NCI-H460; BALB/c nude mice	Suppress NF-κB pathway; Suppress PFN1; Inhibit STAT3	Zheng et al 85 , Gagat et al 86 , Lewis et al 87
Jervine	Veratrum rhizome	A549/H1299; athymic nude mice	Inhibit AKT/mTOR/hedgehog signaling pathway	Lei and Huo 45
Ophiopogon Saponin C1	Liriope muscar	A549; BALB/c nude mice	Block the cell cycle	Zhang et al 88
Kaempferol	Cruciferous vegetables	A549/NCI-H460	Downregulate Nrf-2 signaling pathway	Fouzder et al 89
Cordycepin	Cordyceps sinensis	A549/H1975/PC9; BALB/c mice	Regulate VEGF/PI3K/AKT pathway	Nakamura et al 90

Abbreviations: PI3K, phosphatidylinositol 3-kinase; AKT, Protein Kinase B; VRK, vaccinia-related kinase; P53, tumor protein 53; MMP, matrix metalloproteinase; ROS, reactive oxygen species; STAT, signal transducer and activator of transcription; NF-κB, nuclear factor ƙB; PFN1, Profilin-1; mTOR, mammalian target of rapamycin; Nrf-2, NF-E2-related factor 2; VEGF, vascular endothelial growth factor.

Thevebioside, Sesamin, and Jervine Act Against NSCLC by Inhibiting AKT Signaling

Thevebioside (THB), a monomer from Thevetia peruviana (Pers.) K. Schum. (TPKS), may have pharmacological effects. THB has shown anti-inflammatory effects on skin diseases. ³³ Researchers have found that THB exerts the most cytotoxic activity in p53 wild-type A549 and H460 cell lines in a dose and time-dependent manner. THB has been shown to hinder the proliferation of NSCLC by triggering apoptosis, as indicated by increasing the Bad, cleaved caspase-3 and cleaved PARP expression, and reducing the expression of Bcl-xl. ³⁴ In addition, animal and cell studies have demonstrated that THB promotes apoptosis by inhibiting the steroid receptor coactivator-3 (SRC-3)-induced insulin like growth factor 1 receptor (IGF1R)−P13K-AKT signaling pathway. SRC1, SRC2 and SRC-3 are members of a transcription coactivator family. Elevated SRC-3 expression is frequently associated with tumor progression.^35,36 THB has also exhibited promising pharmacological safety, with low inhibition of normal lung epithelial cells, as well as no observable harm to the organs of A549-bearing mice. ³⁴ THB is a low-toxicity natural product extract that may be employed as an adjuvant medication in lung cancer. Sesamin is a lignan abundant in Sesamum indicum. ³⁷ Sesamin has antihypertension, antithrombosis, and antitumor pharmacodynamic activities.^38-41 Sesamin modulates the AKT/P53 signaling pathway, mainly inhibits AKT activity, and downregulates cyclin D1 and CDK2 in A549 and H1792 lung cancer cells. ⁴² In a previous study, sesamin suppressed AKT/PI3K signaling by downregulating cyclooxygenase 2, leading to G₁ phase cell arrest, and down-regulating Bcl-2, Bax and cyclin E1 gene expression. ⁴³ Yang et al ⁴⁴ showed that sesamin causes an increase in the production of ROS in A549 cells and loss of the mitochondrial membrane potential. Sesamin-treated A549 cells promote the expression of apoptosis-related proteins (cleaved caspase-3, caspase-9, cytochrome c and Bax/Bcl-2). Sesamin stimulated mitophagy in A549 cells via the ROS-mediated PTEN-induced kinase 1 (PINK1)/Parkin signaling pathway, increased Parkin levels in mitochondria and whole cells, and reduced Parkin levels in the cytoplasm. Cyclosporine A, a mitotic inhibitor, abolishes sesamin’s inhibitory effect on A549. ⁴⁴ Sesamin may therefore be a suitable NSCLC adjuvant. Jervine is a steroid alkaloid from Veratrum rhizome. Jervine exhibited a dose and time-dependent inhibition of proliferation and colony formation. ⁴⁵ Jervine promotes the expression of LC3 to induce autophagy and activates caspase-3 to promote apoptosis. Bafilmycina1, an autophagy inhibitor, can abolish the jervine-mediated suppression of human lung cancer cell proliferation. ⁴⁵ Transformation of cytosolic LC3 (LC3-I) into autophagy, the vesicle-associated form (LC3-II) bound by phosphatidylethanolamine, is essential for inducing autophagy. ⁴⁶ The AKT/mTOR and hedgehog signaling pathways are usually strongly suppressed in multiple cancer cells.^47,48 Jervine acts against NSCLC by suppressing hedgehog and AKT signaling. Treatment with jervine effectively suppressed the AKT/mTOR and hedgehog signaling pathways by decreasing the expression of AKT, patched 1, sonic hedgehog, GLI family zinc finger 1 and smoothened, frizzled class receptor. Notably, jervine inhibited tumor growth in A549 tumor-bearing mice. ⁴⁵ Therefore, jervine may become a potential drug for lung cancer treatment.

Thymol Acts Against NSCLC by Arresting the Cell Cycle

Thymol can be found in various plants, including Ocimum gratissimum L. and Satureja thymbra L. Thymol is a naturally occurring monoterpene phenol. A previous study has demonstrated that thymol has important pharmacodynamic effects in antibacterial, antioxidant and analgesic applications. ⁴⁹ In addition, researchers have found that thymol exerts cytotoxic effects in multiple types of cancer.^50-52 Balan et al ⁵³ demonstrated that thymol’s antiproliferative activity on A549 cells was dose and time-dependent, showing IC₅₀ values of 745 μM after 24 hours. Thymol induced cell death by arresting the cell cycle. In the G₀/G₁ phase, the number of cells increased considerably. Moreover, Bax overexpression, Bcl-2 downregulation and apoptotic fragmented DNA were observed, which accelerated cell death. It is worth mentioning that thymol upregulates reactive oxygen species (ROS) levels and changes the mitochondrial membrane potential. ⁵³ Elbe et al ⁵⁴ reported the antitumor activity of thymol on NSCLC KLN205 cells. In the KLN205 cell line, thymol suppressed cell proliferation and promoted cell death. Notably, at 72 hours and 400 μM concentration, apoptosis increased at a higher rate than control in the cells. Koparal and Zeytinoğlu ⁵⁵ found that A549 lung cancer cells treated with 500 and 1000 μM thymol exhibited certain apoptotic features and morphological changes after 24 hours. To summarize, thymol, as a natural chemical, could be used against NSCLC.

Ginseng Inhibits Angiogenesis and Relieves Drug Resistance

Ginseng is a herb that has been used for millennia in China and East Asia. ⁵⁶ The steroid ginsenoside, an extract of ginseng, is the main active component responsible for its anticancer properties.^57,58 Zhang et al ⁵⁹ used a multi-center, prospective, randomized, double-blind trial to assess the effectiveness of Rg3 ginsenoside in patients with advanced NSCLC. A total of 414 patients diagnosed with stage III-IV NSCLC were randomized to combined group (ginsenoside Rg3 + chemotherapy) and chemotherapy group (placebo + chemotherapy). The results showed that the combined treatment alleviated adverse side effects. The combined group had a median survival time of 12.03 months, which was longer than the chemotherapy group’s median survival time (8.46 months) (P < .05). The Karnofsky Performance Scale scores for patients in the combined and chemotherapy groups were 78.95 ± 9.14 and 76.77 ± 9.15, respectively (P < .05). Previous research has demonstrated that the ginsenoside Rg3 in conjunction with chemotherapy may increase overall survival, improve symptoms and alleviate the bone marrow suppression. ⁵⁹ Previous studies have demonstrated that ginsenoside Rg3 exerts antitumor effects by controlling exogenous DNA damage.^60,61 Proto-oncogenes and cancer suppressor genes play vital roles in DNA damage repair. The stress response of cells to DNA damage is critical for preserving genetic material integrity, avoiding gene mutations and sustaining cell function.^62,63 Liu et al ⁶⁴ showed that ginsenoside Rg3 prevents the destruction of DNA integrity by stimulating the vaccinia-related kinase 1 (VRK1)/P53 binding protein 1 (bp1) signaling pathway. VRK1 is a serine-threonine kinase present in the nucleus, which is involved in DNA repair and cell death following DNA damage. P53 bp1 is a downstream protein associated with the VRK1-mediated DNA damage and repair mechanism. VRK1 can recognize the local distortion of chromatin by phosphorylating specific proteins such as P53 bp1, which triggers downstream cascade signaling.^65,66 Ginsenoside Rg3 has been shown to increase chemotherapeutic sensitivity. For instance, combined treatment with ginsenoside Rg3 and osimertinib reduces drug resistance in NSCLC cells ⁶⁷ ; ginsenoside Rg3 downregulates programed death-ligand 1 to reduce A549/DDP cisplatin resistance ⁶⁸ ; and ginsenoside Rg3 has the ability to specifically and effectively reverse icotinib resistance in HCC827 and PC-9 cells. ⁶⁹ These findings suggest that ginsenoside Rg3 may be an effective anti-NSCLC agent.

Cinnamaldehyde (CA) Acts Against NSCLC by Inhibiting the Wnt/β-catenin Signaling Pathway

CA, an anticancer component found in Cinnamomum cassia, ⁷⁰ is effective against a diversity of cancer types, including human oral squamous cell carcinoma and colon cancer.^71,72 Wu et al ⁷³ reported that CA exerts cytotoxicity in NSCLC cells, particularly in the A549, YTMLC-90 and NCI-H1299 cell lines, in which the IC₅₀ was 41.02, 32.30, and 10.50 g/ml, respectively. CA increased Bax gene and protein expression but decreased Bcl-2 and Bcl-xl expression. CA increases E-cadherin and inhibits N-cadherin to block cell motility via reversing the epithelial-mesenchymal transition (EMT). Animal and cell studies demonstrated that CA promote apoptosis by inhibiting the Wnt/β-catenin signaling pathway, as evidenced by reduced expression of β-catenin. Tumor volume and weight decreased in A549-bearing mice following CA treatment. ⁷³ A recent study showed that CA regulated the Wnt/β-catenin signaling pathway via circular RNA Homo sapiens circ 0043256, which induced NCI-H460 and A549 cell death. ⁷⁴ Hong et al ⁷⁵ reported that CA inhibits invasive by downregulating MMP-2 and MMP-9. Park and Baek ⁷⁶ demonstrated that CA and hyperthermia arrest the cell cycle, increase ROS and up-regulate pro-apoptotic protein levels to generate significant cytotoxicity in A549. In addition, the Food and Drug Administration has approved CA as a food ingredient. ⁷⁰

Eupatolide and Piperlongumine Act Against NSCLC by Suppressing STAT3 Signaling

Eupatolide is a new type of terpenoid extracted from the Chinese medicinal plant Inula helenium. ⁷⁷ Research has reported that eupatolide may have inflammatory, analgesic, and antimicrobial activity. ⁷⁸ The action of eupatolide against neoplasms has gained the interest of researchers. ⁷⁹ Cisplatin and 5-fluorouracil are 2 drugs commonly used for NSCLC treatment. Previous studies ⁸⁰ reported that eupatolide markedly increases NSCLC cell chemosensitivity to cisplatin and 5-fluorouracil. Eupatolide may promote A549 and H1975 cell death by downregulating Bcl-2 and myeloid leukemia 1. In nude mice injected with A549 and H1975 cells, oral eupatolide therapy reduce tumor volume for 3 weeks. In addition, eupatolide suppresses STAT3 signaling to promote apoptosis in NSCLC cells. ⁸⁰ Persistent stimulation of STAT3 signaling may cause cancer cells aberrant proliferation and malignant transformation. ⁸¹ Additionally, eupatolide was not toxic. ⁸⁰ Thus, it is likely to be a potential drug for adjuvant antitumor therapy. Piperlongumine, which is isolated from Piper longum L., exhibits anticancer activity in numerous carcinomas.^82-84 Piperlongumine inhibits the phosphorylation and degradation of IκBα, reducing NF-κB p50 and p65 subunit phosphorylation in NSCLC cells. In addition, piperlongumine (15 μM) downregulates Bcl-2 and upregulates Bax, cleaved caspase-3 and cleaved caspase-8 in A549/NCI-H460. In A549 xenografts it was shown that cleaved caspase-3, cleaved caspase-8 and Bax levels increased, while Bcl-2 levels decreased. ⁸⁵ Profilin-1 (PFN1) belongs to the actin-binding protein family. PFN1 has been demonstrated to affect cell migration and apoptosis. Using a wound-healing assay, Gagat et al ⁸⁶ demonstrated that piperlongumine suppresses PFN1 to inhibit migration in A549. Piperlongumine dose-dependently inhibited proliferation and induced cell death. The concentration of piperlongumine at which IC50 was observed was 10.64 μM. Lewis et al ⁸⁷ reported that piperlongumine lowered phosphorylated STAT3 levels and decreased anti-apoptotic protein targets (Bcl-2, Bcl-xl, and cyclin D1). In addition, piperlongumine reduced STAT3 downstream transcriptional targets and suppressed tumor volume. These studies suggest that piperlongumine may become an active anticancer compound.

In addition to these herbal extracts, Ophiopogon saponin C1, kaempferol, and cordycepin are effective against NSCLC. Ophiopogon saponin C1 exerts antitumor effects by modulating kinase activity and blocking the cell cycle to alter the tumor microenvironment. ⁸⁸ Kaempferol, a natural flavonoid, is mainly found in tea, grapes, berries, and cruciferous vegetables. This compound plays an antitumor role primarily by modulating the level of Bcl-2 family proteins that trigger apoptosis. ⁸⁹ Cordycepin acts as an antitumor agent by blocking the cell cycle at G₀/G₁ and by affecting protein expression in the H1975 and PC9 cell lines. ⁹⁰

Herbal Prescriptions Commonly Used in NSCLC Treatment

Traditional herbal prescriptions are usually composed of >2 types of herbal medicine. The ingredients of herbal remedies are complex, but their rich active ingredients exert immunomodulatory and antitumor effects. Herbal prescriptions have been shown to act on different signaling pathways in vivo and in vitro to exert anti-NSCLC effects (Table 3).

Table 3.

Effects of Herbal Prescriptions on Non-small Cell Lung Cancer.

Formula	Ingredients	Extraction method	Preclinical	Clinical	(Refs.)
MaiMenDong and QianJinWeiJing	Ophiopogonis Radix, Ginseng Radix et Rhizoma, Glycyrrhizae Radix et Rhizoma, Pinelliae Rhizoma, Phragmitis Rhizoma, Coicis Semen, Benincasa hispida, Persicae Semen	Water	Inactive Wnt/β-catenin signaling; Inhibit PI3K/AKT pathway	Attenuate the adverse toxicity of Cisplatin	Jiang et al 93 , Xiong et al 94 , Xia et al 95
JinFuKang	Radix astragali, Radix glehniae, Radix asparagi, Fructus ligustri lucidi, Herba selaginellae, Rhizoma paridis yunnanensis, Folium epimedii, Herbal gynostemmatis, Fructus corni, Herba salviae chinensis, Radix Ophiopogon, Semen trigonella	70% ethanol	Block the G2 and M phases of the cell cycle; Active Fas and DR4	prolong survival in patients with stage II/III NSCLC (JinFuKang + Cisplatin)	Lu et al 96 , Han 97 , Liu et al 98 , Jiao et al 99 , Huang et al 100
BuZhongYiQi	Astragali Radix, Glycyrrhizae Radix, Codonopsis Radix, Angelicae Sinensis Radix, Citri Reticulatae Pericarpium, Cimicifugae Rhizoma, Bupleuri Radix, Atractylodis Macrocephalae Rhizoma	Water	Induce ROS accumulation Reduced Bcl-2, increased Bax levels; Upregulate LC3-II,ATG7 levels	Improve patient symptoms and systemic inflammation; reduce the adverse toxicity of paclitaxel	Yu et al 105 , Ouyang et al 106 , Satoh et al 107 , Tatsumi et al 108
WenXiaChangFu	Aconiti Lateralis RadixPraeparata, Ginseng Radix et Rhizoma, Angelicae Sinensis Radix, Rhei Radix et Rhizoma	Water	Suppress integrin β/PI3K/AKT signaling pathway; Block the cell cycle; mitigate drug resistance	No reports in English	Ji et al 109 , Zhang et al 110 , Ji et al 111 , Wang et al 112
LianJiaSanJie	Scutellariae Radix, Trionycis Carapax, Sarcandrae Herba, Ranunculus ternatus Thunb, Adenophorae Radix, Glehniae Radix, Pseudostellariae Radix, Ophiopogonis Radix, Asparagi Radix, Rubia cordifolia, Pinelliae Rhizoma, Hedyotidis Herba, Bombyx Batryticatus, Inula japonica	Water	Regulate EGRF/ p53 signaling pathway; mitigate drug resistance	No reports in English	Wang et al 113 , Liu 114
BuFei	Codonopsis pilosula, Schisandra chinensis, Rehmannia glutinosa, Astragalus, Aster and Cortex Mori.	Water	Inhibit PD-L1 and IL-10 expression; Suppress Canonical Smad signaling pathway; Inhibit TGF-β1 mediated EMT	Extend the disease-free survival of patients with stage II-IIIA NSCLC	Pang et al 115 , He et al 116 , Zhao et al 117 , McCulloch et al 118

Abbreviations: PI3K, phosphatidylinositol 3-kinase; AKT, Protein Kinase B; Fas, Death receptor; DR, Death receptor; Bcl-2, B-cell lymphoma-2; Bax, Bcl-2 Associated X Protein; LC3, MAP1LC3; ATG, autophagy related gene; EGRF, epidermal growth factor receptor; P53, tumor protein 53; IL, interleukin; PD-L1, programed death-ligand 1.

Maimendong and Qianjin Weijing decoction are oriental prescriptions for treating “pulmonary carbuncles,” as recorded in traditional Chinese medicine classic books over 1000 year ago. Maimendong and Qianjin Weijing decoction are composed of 8 Chinese medicinal herbs: Ophiopogonis Radix, Ginseng Radix et Rhizoma, Glycyrrhizae Radix et Rhizoma, Pinelliae Rhizoma, Phragmites Rhizoma, Coicis Semen, Benincasa hispida, and Persicae Semen. In modern pharmacological trials, Maimendong and Qianjin Weijing decoction was able to suppress cell proliferation and induce NSCLC cell death.^91,92 Jiang et al ⁹³ showed that Maimendong and Qianjinweijing decoction acted on the Wnt signaling pathway to induce the expression of microRNA (miR)-149-3p and inhibit the expression of may-associated zinc-finger protein (MAZ), c-Myc and cyclin D1, thus inhibiting NSCLC cell metastasis. A study reported a significant inhibitory effect of Maimendong and Qianjin Weijing decoction combined with cisplatin on A549 xenografts in nude mice, mainly through inhibition of p-AKT and p-PTEN expression and down-regulated Bcl-2. ⁹⁴ A clinical study revealed that Maimendong decoction combined with cisplatin was more effective than cisplatin alone in 19 patients with NSCLC. ⁹⁵

Jinfukang (JFK) decoction (JFKD) is an herbal prescription approved by the Food and Drug Adiministration for NSCLC therapy. JFK is composed of 12 herbs, including Radix astragali, Radix glehniae, Radix asparagi, Fructus ligustrum Lucidi, Herba selaginella, Rhizoma paradise yunnanensis, Folium epimedii, Herbal gynostemmatis, Fructus corni, Herba salviae chinensis, Radix Ophiopogon, and Semen trigonella. Lu et al ⁹⁶ stated that JFKD prescriptions may be associated with Fas and DR4 activation to cause apoptosis. Research has shown that JFK prescriptions act as tumor inhibitors in human lung cancer cells by blocking cancer cells due to its inhibitory effect on DNA. ⁹⁷ In addition, clinical reports have shown that JFKD combined with cisplatin chemotherapy prolongs survival in patients with stage II/III NSCLC, improves immune parameters and reduces cisplatin-related side effects.^98-100

Buzhong Yiqi (BZYQ) decoction (BZYQD) first appeared in the book “Spleen and Stomach Theory” by Li Dongyuan >700 years ago, which focused on prescriptions for treating visceral ptosis, chronic gastrointestinal diarrhea, and other spleen and stomach diseases. ¹⁰¹ Previous studies reported that high concentrations of BZYQ can cause gastric cancer and ovarian neoplasm tumor cell death by regulating apoptosis. ¹⁰² BZYQ contains 8 herbs: Astragali Radix, Glycyrrhizae Radix, Codonopsis Radix, Angelicae Sinensis Radix, Citri Reticulatae Pericarpium, Cimicifugae Rhizoma, Bupleuri Radix, and Atractylodis Macrocephalae Rhizoma. Gou et al ¹⁰³ confirmed that BZYQD could reduce gastrointestinal damage by inhibiting the expression of inflammatory cytokines. Moreover, BZYQD reduces kidney damage in mice through antioxidant mechanisms. ¹⁰⁴ Yu et al ¹⁰⁵ demonstrated that BZYQ could reduce the resistance of the A549/DDP cell line to cisplatin, making the A549/DDP cell line more sensitive to chemotherapy. Previous clinical studies showed that BZYQ combined with conventional chemotherapy drug effectively improved patient symptoms and systemic inflammation. Additionally, BZYQ prescriptions can alleviate fatigue caused by the chemotherapeutic drug paclitaxel and improve lung cancer survival.^106-108

WenXiaChangFu (WXC), a commercial herbal prescription, comprises Aconiti Lateralis Radix Praeparata, Ginseng, Angelicae Sinensis Radix, and Rhei Radix et Rhizoma. Ji et al ¹⁰⁹ reported that WXC mitigated cisplatin resistance by inducing cell death. Previous studies have indicated that WCF acts on the A549 cell line, and in a nude mouse model, it can inhibit the integrin β/PI3K/AKT signaling pathway to reverse drug resistance. ¹¹⁰ Previous studies revealed that WXC prescriptions with cisplatin may effectively suppress tumors by block the cell cycle and induce apoptosis.^111,112

Lianjia Sanjie decoction (LJSJD) is a composition of 14 herbs mainly used as a lung cancer adjuvant therapy, including Scutellariae Radix, Trionycis Carapax, Sarcandrae Herba, Ranunculus terminates Thunb, Adenophorae Radix, Glehniae Radix, Pseudostellariae Radix, Ophiopogonis Radix, Asparagi Radix, Rubia cordifolia, Pinelliae Rhizoma, Hedyotidis Herba, Bombyx Batryticatus, and Inula japonica. Wang et al ¹¹³ showed that LJSJD prescriptions had a pronounced cytotoxic effect on A549, H460, H1650 and H1975 cells. Additionally, LJSJD prescriptions could inhibit EGFR mutations and stimulate the expression of P53. LJSJD prescriptions have been shown to mitigate gefitinib drug resistance in lung cancer cell lines. ¹¹⁴

BuFei decoction (BFD) is a conventional Chinese medicine prescription formulated to treat lung cancer. The medicinal ingredients of BFD include Codonopsis pilosula, Schisandra chinensis, Rehmannia glutinosa, Astragalus, Aster, and Cortex Mori. Previous studies showed that BFD inhibits IL-10 and PD-L1 expression to interrupt the association between TAMs and NSCLC cells (A549, H1975). ¹¹⁵ He et al ¹¹⁶ showed that BFD blocks cancer cell metastasis by the Smad signaling pathway, thus inhibiting the TGF-β1-induced EMT process, thereby exerting an antitumor effect. In the clinic, BFD as an adjuvant therapy could mitigate tumor recurrence rates, modulate human immunological functions, and extend the disease-free survival of patients with stage II-IIIA NSCLC.^115,117,118

In summary, the multicomponent and multitarget effects of traditional herbal prescriptions effectively prevent cancer and overcome drug resistance. The above studies have shown that herbal prescriptions have a potential as adjuvant cancer therapy. Clinical studies should be conducted to explore their mechanism of action.

Discussion

As NSCLC gradually progresses, the applications of traditional herbal medicine attract increasing attention. Whether in combination with chemotherapy drugs or by alleviating chemotherapy-related adverse side effects in patients with cancer, herbal medicine provides an optional adjuvant treatment for clinicians. Apoptosis is a form of cell death vital for the human body to maintain its proper function and is frequently a major factor in herbal anticancer treatment. Apoptosis occurs via nuclear fragmentation, cell contraction, cell membrane blistering, chromosome DNA breakage and chromatin concentration.^119,120 Internal pathways (also known as mitochondrial pathways) and exterior pathways (also called death receptor pathways) participate in the apoptotic process. The mitochondrial pathway primarily involves the Bcl-2 family. The pro-apoptotic Bcl-2 family of proteins can be transported to the mitochondrial outer membrane to secrete pro-apoptotic factors and activate caspase-9, which triggers caspase-3 activation and finally induces apoptosis. Conversely, anti-apoptotic proteins in the Bcl-2 family often act as inhibitors of apoptosis. ¹²¹ The exogenous apoptosis pathway activates caspase-8 by enhancing death receptor expression, which directly cleaves or activates downstream caspases to transmit apoptotic signals. ¹²¹ Autophagy involves autophagosomes phagocytizing proteins and organelles, and then transporting them to lysosomes. Autophagy can promote tumor proliferation while also causing tumor cell death. ¹²² Previously, it was reported that puerarin may regulate LC3II/LC3I and autophagy related 5 expression by PI3K/AKT signaling pathways, ultimately inducing the cancer cells autophagic death. ¹²³ Thus, apoptosis and autophagy may be beneficial in preventing and treating NSCLC. Cell proliferation and metastasis are linked to cancer-related mortality and poor prognosis. Tumor metastasis is the product of cell biological processes involving numerous aspects, such as cell adhesion, extracellular matrix degradation, tumor cell migration and invasion. ¹²⁴ It has been shown that, in NSCLC, brain and liver are common tumor metastatic organs. ¹²⁴ Herbal extracts have been reported to exhibit potential efficacy in inhibiting neoplasm metastasis. Marine-mediated inhibition neoplasm metastasis is generally associated with the migration-related gene paired box 2 (PAX2). ¹²⁵ Patients with cancer often have high expression levels of the PAX2 gene. Overexpression of the PAX2 gene may contribute to tumorigenesis, but it may be a useful tumor marker. ¹²⁵ The cell cycle is divided into 4 phases: G₁, S, G₂, and M. Inhibiting the cell cycle can block tumor progression. ¹²⁶ Herbal extracts such as praeruptorin C block the cell cycle and induce cell death by controlling cyclin D1 and p21 proteins. ¹²⁷ Polyphyllin D induces G0/G1 cell cycle arrest and downregulates cyclin D1 expressions by upregulating the level of sex-determining region Y-box 7 (SOX7) transcription factor. ¹²⁸ Garg et al ¹²⁹ reported that SOX7 acts as a tumor suppressor in lung tissue, especially in NSCLC cell lines (H23 and H1299). It was found that stimulating the high expression of SOX7 could significantly induce apoptosis and inhibit cell proliferation. Aberrant activation of signaling pathways is critical in tumor progression. Herbal medicine may selectively interfere with cancer cells at different stages by regulating different signaling pathways, thereby playing an auxiliary antitumor effect. The Wnt signaling pathway is one of the classical signaling pathways, and its mis-regulation is common in NSCLC. The Wnt signaling pathway is responsible for regulating various behaviors associated with tumor cells, including proliferation, invasion, metabolic activity, apoptosis, and inflammation. In orthotopic xenografts, Jiang et al ⁹³ observed that Maimendong and Qianjinweijing prescriptions reduced Wnt target gene expression, particularly miR-149-3p, and thus had an anti-NSCLC effect. CA, the most cytotoxic component in Cinnamomum cassia, blocks NSCLC proliferation by regulating the Wnt signaling pathway. ⁷³ AKT signaling pathway activation is often positively correlated with neoplasm occurrence. AKT signaling pathway is frequently aberrantly activated in lung cancer, leukemia, gastric cancer, and other cancer types, so inhibiting AKT signaling pathway could effectively prevent tumor proliferation and migration. ¹³⁰ Therefore, targeting the AKT signaling pathway may provide potential anti-NSCLC effects. The NF-κB signaling pathway is crucial in anti-cancer activity, inducing apoptosis, blocking the cell cycle and suppressing the inflammatory response. ¹³¹ The formula YangYinWenYang regulates inflammatory cytokine levels and inhibits NF-κB signaling pathway. ¹³² Zheng et al ⁸⁵ found that piperlongumine, a potential anti-tumor herbal extracts, blocks NF-κB and DNA binding activity. In conclusion, the common pathways involved in anti-NSCLC are P13K/AKT, Wnt, and NF-κB signaling pathways, which can be inhibited by acting on different targets. Also, herbal medicine inhibits anti-apoptotic protein levels while inducing pro-apoptotic protein expression, leading to cancer cell apoptosis. In addition to the main signaling pathways mentioned above, some herbal extracts or prescriptions use different anti-tumor mechanisms. The herbal extracts also act on the STAT3 signaling pathway and Hedgehog signaling pathway to inhibit NSCLC by regulating these pathways’ upstream and downstream related proteins. STAT3 plays a vital role in human malignancies. It regulates cell apoptosis, cell proliferation, and angiogenesis. ¹³³ On the other hand, STAT3 signaling overexpression promotes drug resistance and induces cell metastasis. ¹³⁴ Garg et al ¹³⁴ summarized that several potential natural product-derived small molecules inhibit STAT3 signaling, such as formononetin, zerumbone, garcinol, and others, providing a reference for new drug discovery in the future. The herbal prescriptions inactivate the classical Smad signaling pathway by regulating the expression of TGF-β1. Figure 1 summarizes the study of herbal medicine treatment for NSCLC (Figure 1).

Figure 1.

Study of herbal medicine treatment for non-small cell lung cancer. Animal experiments, clinical trials and molecular biology studies of herbal extracts and herbal prescriptions to inhibit the growth of NSCLC are graphically and vividly presented in this diagram. This figure was created with Biorender.com.

Conclusion

To summarize, herbal medicine has the potential to be used as adjunctive therapy for NSCLC. With the advancement in systems biology, a more profound and systematic knowledge of herbal treatment has been obtained. The practice of herbal medicine has progressively evolved into a medical system based on evidence rather than the practitioner’s own experiences. Herbal medicines inhibit tumor progression and improve chemoradiotherapy sensitivity mainly through the P13K/AKT signaling pathway, Wnt signaling pathway, NF-κB signaling pathway. Additionally, some herbal extracts and prescriptions exert multi-target, pleiotropic effects by regulating related apoptosis proteins (Bad, Bax, Bcl-xl, Bcl-2), ROS levels, and upstream and downstream proteins affecting related pathways. They act to achieve network regulation and ultimately produce tumor-inhibiting effects. In NSCLC treatment, Chinese herbal medicine combined with radio-chemotherapy can improve efficacy, alleviate the toxicity and adverse side effect caused by radio-chemotherapy, and prolong progression-free survival. By reviewing and summarizing these drugs, it is helpful to discover that herbal medicine may be applied as a potential adjunct treatment to NSCLC in the future and provide useful information for the development of effective new drugs. However, there are limitations in the published studies. Research on herbal medicines is still mainly based on cell and animal experiments. Clinical trials are rare in the literature; thus, further studies should be conducted to confirm their safety and efficacy. In conclusion, Chinese herbal medicine inhibits tumor growth through induces apoptosis of tumor cells, inhibits metastasis of cancer cells, reverses the resistance of conventional chemotherapeutic drugs and so on. Clinically, Chinese herbal medicine combined with traditional chemotherapeutic drugs may increase effectiveness and reduce toxicity.