Sage Journals: Discover world-class research

Abstract

BACKGROUND AND AIM:

Hypercalcemia is a potentially fatal and not rare complication of hepatocellular carcinoma (HCC), and its underlying mechanism remains unclear. Parathyroid hormone (PTH) is the most important regulator of the concentrations of calcium and phosphate in blood; parathyroid hormone-related protein (PTHrP) was the most frequent cause of humoral hypercalcemia of malignancy; parathyroid hormone 1 receptor (PTH1R) is the common receptor for PTH and PTHrP. The aim of this study is to investigate the expression of PTH, PTHrP, and PTH1R in HCC tissues, and their relationship with clinical pathological characters in HCC.

METHODS:

First, a meta-analysis based on online Oncomine Expression Array database was conducted to compare the different mRNA expression of PTH1R, PTH and PTHrP between hepatocellular carcinoma and normal tissues. Then, the protein expression level of differentially expressed gene was examined by immunohistochemistry staining in 223 HCC tissues and 102 non-tumorous liver tissues controls. The relationship between the protein expression and clinicopathological parameters was analyzed by $\chi$ 2 test, and overall survival analysis was performed using Kaplan-Meier survival analysis.

RESULTS:

PTH1R mRNA expression was significantly lower in HCC tissues compared with normal tissues, while the expression of PTH and PTHrP showed no significant difference between HCC tissues and normal tissues. High PTH1R protein expression was found in 90/102 cases of adjacent non-tumorous liver tissues, and in 91 of 223 cases of HCC tissues. PTH1R expression was significantly related to tumor size, Edmondson Grade, AFP, and overall survival.

CONCLUSIONS:

PTH1R may be the major cause of hypercalcemia in HCC, and the decreased PTH1R expression was a poor prognosis in HCC.

Keywords

PTH1R PTH PTHrP hepatocellular carcinoma

1. Introduction

G-protein coupled receptors (GPCRs) constitute a large protein family of receptors. Based on sequence homology and functional similarity, GPCRs can be grouped into 6 classes: Class A (Rhodopsin- like), Class B (Secretin receptor family), Class C (Metabotropic glutamate/pheromone), Class D (Fungal mating pheromone receptors), Class E (Cyclic AMP receptors), and Class F (Frizzled/Smoothened). GPCRs are involved in and regulate various physiological functions [1, 2, 3]. Dysfunction of GPCRs may lead to the occurrence and development of many diseases. Also, GPCRs are the targets of approximately 40% of all modern medicinal drugs [4, 5].

Parathyroid hormone 1 receptor (PTH1R), belongs to the class B G-protein coupled receptor family, is the common receptor for parathyroid hormone (PTH) and parathyroid hormone-related protein (PTHrP). PTH is the most important regulator of the concentrations of calcium and phosphate in blood. It is mainly produced by the parathyroid glands, as a 115-amino acid precursor (pre-pro-PTH), and cleaved to pro-PTH with a prosequence of 6 amino acids, and then to the 84-amino acid mature PTH [6, 7]. Mature PTH is then secreted into blood and acts primarily on kidney and bone, promotes osteoclastic bone resorption and renal tubular calcium reabsorption, and inhibits renal tubular phosphate reabsorption [8, 9]. The biological actions of PTH are mediated by binding of its N-terminal region (aa 1–34) to PTH1R, which was highest expressed in kidney and bone [7, 10]. PTHrP, also called parathyroid hormone like hormone (PTHLH), was first identified from tumors associated with the syndrome of humoral hypercalcemia of malignancy, and considered as the most frequent cause of humoral hypercalcemia of malignancy [11, 12]. PTHrP was also produced by non-hypercalcemic tumors, and responsible for the osteolysis [13, 14, 15]. Sequence analysis showed that PTHrP was significant sequence homology within the first 13 amino acid residues to PTH, and bind to the same receptor PTH1R [16]. Further studies showed that PTHrP was not confined in tumors; it was also widely expressed in normal tissues and with multiple biological activities [17, 18]. PTH1R was the common receptor of PTH and PTHrP. When PTH1R bind with PTH or PTHrP, it was internalize activated, and subsequently activated the adenylyl cyclase/protein kinase A (AC/PKA) pathway and the phospholipase C/protein kinase C (PLC/PKC) pathway [19, 20, 21]. Defects in PTH1R was the cause of chondrodysplasia and primary failure of eruption [22, 23], while over-expression of PTH1R was found in osteosarcoma and breast cancer, and conferred an aggressive phenotype [24, 25].

Hypercalcemia, hypophosphataemia, bone thinning and fractures, are the common complications of chronic liver disease [26], while the mechanism was still not well understood. In this study, we first performed a meta-analysis on Oncomine Expression Array database to evaluate the expression of PTH1R, PTH and PTHrP, the three most important regulators of calcium and phosphate, and found only expression of PTH1R was significantly reduced in HCC tissues when compared with normal liver tissues; then, we examined PTH1R expression in 223 hepatocellular carcinoma (HCC) tissues and 102 non-tumorous liver tissues by immunohistochemistry staining, and investigated the relationships between PTH1R expression and clinicopathological parameters, and the overall survival rate. This study might provide further insight into the cause of bone thinning and fractures, hypercalcemia and hypophosphataemia in HCC cancers.

2. Materials and methods

2.1 Oncomine database analysis

A meta-analysis based on online Oncomine Expression Array database (www.oncomine.org) was conducted to compare the different expression of PTH1R, PTH, and PTHLH between hepatocellular carcinoma and normal tissues, using the following terms: “PTH1R”, “PTH”, “PTHLH”, “Cancer vs. Normal Analysis”, “Hepatocellular Carcinoma”, and “mRNA”. In total, five datasets, including Chen Liver [27], Roessler Liver [28], Roessler Liver 2 [28], Wurmbach Liver [29], and Mas Liver [30] were selected to determine the expression of PTH1R, PTH, and PTHLH.

2.2 Patients and tissue samples

All the human tissues were obtained from surgical resection specimens of HCC patients at Zhejiang Provincial People’s Hospital, Hangzhou, China. This study was approved by the Ethics Committee of Zhejiang Provincial People’s Hospital, Hangzhou, China. Written informed consent was provided by the patients.

Figure 1.

Expression of PTH1R in normal liver and hepatocellular carcinoma tissues based on Oncomine database.

Two hundred and twenty-three cases of paraffin-embedded HCC tissues and 102 non-tumorous liver tissues were obtained from April 2008 to September 2014. The patient cohort consisted of 177 males and 46 females, with a median age of 58.15 years (range: 25–90) at the time of surgery. The survival time was calculated from the date of surgery to the follow-up deadline or the date of death. All tissues were used for tissue microarray (TMA), constructed by Shanghai Biochip Co., Ltd, Shanghai, China.

2.3 Immunohistochemical staining and evaluation

Immunohistochemical staining was performed using Histostain-Plus IHC Kit (Invetrogen, USA), according to the manufacturer’s instructions. Briefly, 5 $\mu$ m sections from the TMAs were baked at 70 ${}^{\circ}$ C for 2 h, followed by de-paraffinized, rehydrated. Then, the sections were boiled within TE buffer using a high pressure cooker for 3 min to retrieve antigen, blocked with 3% H ${}_{2}$ O ${}_{2}$ for 15 min to inhibit endogenous peroxidase activity, and incubated with 10% goat non-immune serum for 20 min to reduce background non-specific staining. After that, the sections were incubated with the rabbit anti-PTH1R monoclonal antibody (abcam, Cambridge, UK, EPR15892) (1:100 dilution) at 4 ${}^{\circ}$ C overnight, then followed by incubation with biotin-labeled secondary antibody at room temperature for 20 min, and HRP-conjugated streptavidin at room temperature for 20 min. Color development was performed with DAB Kit (ZSGB-BIO, China). Finally, the sections were counterstained with hematoxylin, dehydrated, cleared, and mounted.

The immunohistochemical stain of PTH1R was scored independently by two pathologists, based on the intensity and the proportion of positively stained cells. Staining intensity was evaluated with a four-tiered grading system: 0 $=$ negative, 1 $=$ weak, 2 $=$ moderate, and 3 $=$ strong. The percentage of positive cells were scored as follows: 0 for no cell stained, 1 for 1%–25% of cells stained, 2 for 26–50% of cells stained, 3 for more than 50% of cells stained. Scores for intensity and percentage of positive cells were then multiplied to give an overall evaluation. Scores $\leqslant$ 3 was used to define tumors for low PTH1R expression and scores $\geqslant$ 4 for high PTH1R expression.

2.4 Statistical analysis

Statistical analysis was performed using Statistical Program for Social Sciences (SPSS) software 13.0 (SPSS Inc., Chicago, IL, USA). The $\chi$ 2 tests were applied to assess the statistical significance of the associations between PTH1R protein expression and clinicopathological parameters. Survival curves were estimated using the Kaplan-Meier method, and the log-rank test was used to calculate differences between the curves. $P$ value less than 0.05 was considered statistically significant.

Figure 2.

Expression of PTH in normal liver and hepatocellular carcinoma tissues based on Oncomine database.

Figure 3.

Expression of PTHLH (PTHrP) in normal liver and hepatocellular carcinoma tissues based on Oncomine database.

3. Results

3.1 Analysis of PTH1R, PTH, PTHrP expression based on Oncomine database

Firstly, we analyzed the Oncomine databases to compare PTH1R, PTH, PTHrP mRNA expression in hepatocellular carcinoma vs. normal tissues, and found that PTH1R mRNA expression was significantly lower in HCC tissues compared with normal tissues (Fig. 1, all $P<$ 0.001). The expression of PTH in HCC tissue was slightly lower than that in normal tissues with no statistical significance (Fig. 2). The expression of PTHrP was slightly high in HCC tissue with no statistical significance (Fig. 3). Then, PTH1R was chosen for further immunohistochemical staining.

Figure 4.

Immunohistochemical staining of PTH1R in non-tumorous liver tissues. A: normal liver tissue; B: Inflammatory tissues; C: Cirrhosis tissues.

Figure 5.

Strong (A), Moderate (B), and Negative (C) expression of PTH1R in HCC tissues.

3.2 Expression of PTH1R in HCC and adjacent non-tumorous tissues

Table 1
Expression of PTH1R in non-tumorous liver tissues

Samples	Number	PTH1R expression
		Low	High
Normal liver tissues	36	5	31
Inflammatory tissues	32	1	31
Cirrhosis tissues	34	6	28

Immunostaining of PTH1R was positive in cytoplasm and negative in nucleus in non-tumorous liver and HCC tissues. PTH1R was found highly expressed in 90 of the 102 (88.23%) cases of adjacent non-tumorous liver tissues (29 cases of normal liver tissues, 36 cases of inflammatory liver tissues, and 25 cirrhotic liver tissues), only 12 cases were PTH1R low expression (Table 1 and Fig. 4). The expression of PTH1R was significantly reduced in HCC tissues. High expression of PTH1R was found in 91 of 223 (40.81%) HCC tissues (Fig. 5).

Table 2

Relationship between PTH1R expression and pathological parameters of HCC

Clinical parameters	All cases	PTHR1		$P$ value
		$-$	$+$
Age (years)				0.328
$<$ 55	87	55	32
$\geqslant$ 55	136	77	59
Gender				0.108
Male	177	100	77
Female	46	32	14
Size				0.006
$<$ 5	115	58	57
$\geqslant$ 5	103	71	32
Tumour number				0.149
Single	181	103	78
Multiple	42	29	13
Edmondson Grade				0.001
I $+$ II	143	73	70
III	78	57	21
Metastasis				0.501
M0	205	120	85
M1	18	12	6
Microvascular invasion				0.933
Absence	76	47	29
Presence	80	50	30
HBs antigen				0.320
Negtive	45	24	21
Positive	174	107	67
Cirrhosis				0.553
Negtive	71	40	31
Positive	152	92	60
AFP				0.018
$<$ 50	104	51	53
$\geqslant$ 50	101	66	35
Status				0.024
Alive	88	51	37
Dead	45	35	10

3.3 Correlation between PTH 1R expression and clinicopathologic parameters

The correlation between expression of PTH1R and clinical variables was shown in Table 2. The PTH1R expression was significantly related to tumor size, Edmondson Grade and AFP. The expression of PTH1R in tumor with big size, high Edmondson Grade, or high AFP level was significantly lower than that in tumor with small size, low Edmondson Grade, or AFP level. There was no significant correlation between PTH1R expression and other clinicopathologic parameters.

3.4 Survival analysis

Kaplan-Meier survival analysis showed that the 5-year cumulative survival rate for patients with low PTH1R expression was 59.2%, whereas of the patients with high PTH1R expression was 73.5%. The mean survival time of the patients with low PTH1R expression was 40.08 $\pm$ 2.68 months, which was significantly lower that of patients with high PTH1R expression (49.22 $\pm$ 2.03, $P=$ 0.034). It seemed that low expression of PTH1R was associated with poor overall survival (Fig. 6).

Figure 6.

Kaplan-Meier survival curves of the HCC patients with high or low PTH1R expression.

4. Discussion

Hepatocellular carcinoma (HCC) is a common malignant tumor of digestive system, ranks fourth in cancer incidence and third in cancer mortality in China [31]. Hypercalcemia is a potentially fatal and not rare complication of HCC. The most common cause of hypercalcemia is excess PTH released by the parathyroid glands. Sometimes, certain cancers, such as breast cancer, lung cancer, and certain blood cancers, could release PTHrP and result calcium release from the bones into the bloodstream [11, 12]. In addition, metastasis, or spreading of a cancer to the bones also can increase the risk of hypercalcemia. In this study, we analyzed the expression of PTH1R, PTH, and PTHrP, the three most important regulators of calcium and phosphate, in HCC. A meta-analysis on online Oncomine Expression Array database showed that the expression of PTH1R in 415 cases of HCC tissues was significantly lower than that in 346 cases of normal liver tissues. Further immunohistochemical staining also confirmed the decreased expression of PTH1R in HCC tissues. There was no significant difference between the expression of PTH in HCC and normal liver tissues. Although there are a few case reports and studies with small sample size showed that high PTHrP expression in HCC patients with hypercalcemia [32, 33, 34, 35], the meta-analysis showed that PTHrP mRNA was slightly higher in HCC tissue than in normal tissues, with no statistical significance. These results suggested that decreased expression of PTH1R may be the major cause of hypercalcemia in HCC.

The underlying mechanism of hypercalcemia in HCC is still unclear. As previous studies reported, both liver and kidneys contribute to the clearance of circulating intact PTH, which may involve receptor-triggered endocytosis mediated by the PTH1R. It was reported that Kupffer cells could uptake intact PTH, proteolyse N-terminal portion of the PTH, and generate various circulating C-terminal PTH peptide (CPTH) fragments; while hepatocytes and sinusoidal cells could uptake both intact PTH and N-PTH fragments [36, 37, 38]. Kidneys are crucial in clearance from blood of both intact PTH and, especially, CPTH fragments [36, 39]. In combination with existing reports and our results, we present hypotheses: decreased expression of PTH1R in HCC tissues reduced the clearance of circulating PTH, which result in retention of PTH in blood, and the subsequently hypercalcemia, hypophosphataemia, bone thinning and fractures. On the other hand, failure of clearance of circulating PTH by liver and the subsequently hypercalcemia increased kidney burden.

Besides, the decreased expression of PTH1R in HCC is also contrary to the previous studies in other malignant tumors. Over-expression of PTH1R has been detected in numbers of neoplastic tissues, including colorectal carcinoma, prostate cancer, renal cell carcinoma and osteosarcoma [10, 24]. Over-expression of PTH1R conferred an aggressive phenotype in osteosarcoma, and PTHR1 knockdown resulted in a profound inhibition on invasion and growth in osteosarcoma cells [24, 40]. PTH1R was also frequently expressed in breast cancer bone metastases, and drived proliferation via cAMP and ERK pathways, while PTH1R silencing suppressed cell proliferation [25]. However, in this study, we found decreased expression of PTH1R was significantly related to big tumor size, high Edmondson Grade, high serum AFP level and poor overall survival. Similar to HCC, meta-analysis based on Oncomine database also showed significantly down-regulation of PTH1R in renal carcinoma, and survival analysis with TCGA data showed that low expression of PTH1R was a poor prognosis in patients with renal carcinoma (data not shown). This may due to the biological roles of PTH1R in liver and kidneys in the clearance of PTH. The mechanisms involved in PTH1R down-regulation and downstream regulation pathway in HCC remain explore.

In conclusion, our results indicated that the decreased expression of PTH1R may be the main cause of hypercalcemia in HCC. Decreased expression of PTH1R was associated with tumor size, Edmondson Grade, serum AFP level and poor overall survival, and was a poor prognosis in HCC.

Footnotes

Acknowledgments

This work was supported by the grants from the National Science Foundation of China (81602174 and 81672430), Zhejiang Provincial Natural Science Foundation of China (LY16H160042 and LY17H160062), Funds of Science Technology Department of Zhejiang Province (No. GF18H160059, GF18H160061, 2015C37089), Zhejiang Province Bureau of Health (Nos. 2018ZZ002, WKJ-ZJ-1710, and 2015ZA009).

Conflict of interest

None.

References

Smrcka

A.V.

, Fingerprinting G protein-coupled receptor signaling, Sci Signal 8 (2015), fs20.

Kolakowski

L.F.

, Jr., GCRDb: a G-protein-coupled receptor database, Receptors Channels 2 (1994), 1–7.

Foord

S.M.

Bonner

T.I.

Neubig

R.R.

Rosser

E.M.

J.P.

Davenport

A.P.

Spedding

and Harmar

A.J.

, International Union of Pharmacology. XLVI. G protein-coupled receptor list, Pharmacol Rev 57 (2005), 279–288.

Lian

Geng

Qian

Zhen

and Fu

, A computational perspective on drug discovery and signal transduction mechanism of dopamine and serotonin receptors in the treatment of schizophrenia, Curr Pharm Biotechnol 15 (2014), 916–926.

Gurrath

, Peptide-binding G protein-coupled receptors: new opportunities for drug design, Curr Med Chem 8 (2001), 1605–1648.

Freeman

M.W.

Wiren

K.M.

Rapoport

Lazar

Potts

J.T.

, Jr. and Kronenberg

H.M.

, Consequences of amino-terminal deletions of preproparathyroid hormone signal sequence, Mol Endocrinol 1 (1987), 628–638.

Wiren

K.M.

Potts

J.T.

, Jr. and Kronenberg

H.M.

, Importance of the propeptide sequence of human preproparathyroid hormone for signal sequence function, J Biol Chem 263 (1988), 19771–19777.

Fraser

D.R.

and Kodicek

, Regulation of 25-hydroxych- olecalciferol-1-hydroxylase activity in kidney by parathyroid hormone, Nat New Biol 241 (1973), 163–166.

Komarova

S.V.

, Mathematical model of paracrine interactions between osteoclasts and osteoblasts predicts anabolic action of parathyroid hormone on bone, Endocrinology 146 (2005), 3589–3595.

10.

Lupp

Klenk

Rocken

Evert

Mawrin

and Schulz

, Immunohistochemical identification of the PTHR1 parathyroid hormone receptor in normal and neoplastic human tissues, Eur J Endocrinol 162 (2010), 979–986.

11.

Burtis

W.J.

Bunch

Wysolmerski

J.J.

Insogna

K.L.

Weir

E.C.

Broadus

A.E.

and Stewart

A.F.

, Identification of a novel 17,000-dalton parathyroid hormone-like adenylate cyclase-stimulating protein from a tumor associated with humoral hypercalcemia of malignancy, J Biol Chem 262 (1987), 7151–7156.

12.

Moseley

J.M.

Kubota

Diefenbach-Jagger

Wettenhall

R.E.

Kemp

B.E.

Suva

L.J.

Rodda

C.P.

Ebeling

P.R.

Hudson

P.J.

Zajac

J.D.

et al., Parathyroid hormone-related protein purified from a human lung cancer cell line, Proc Natl Acad Sci U S A 84 (1987), 5048–5052.

13.

Liao

Koh

A.J.

Berry

J.E.

Thudi

Rosol

T.J.

Pienta

K.J.

and McCauley

L.K.

, Tumor expressed PTHrP facilitates prostate cancer-induced osteoblastic lesions, Int J Cancer 123 (2008), 2267–2278.

14.

Liao

and McCauley

L.K.

, Skeletal metastasis: Established and emerging roles of parathyroid hormone related protein (PTHrP), Cancer Metastasis Rev 25 (2006), 559–571.

15.

Isowa

Shimo

Ibaragi

Kurio

Okui

Matsubara

Hassan

N.M.

Kishimoto

and Sasaki

, PTHrP regulates angiogenesis and bone resorption via VEGF expression, Anticancer Res 30 (2010), 2755–2767.

16.

Kemp

B.E.

Moseley

J.M.

Rodda

C.P.

Ebeling

P.R.

Wettenhall

R.E.

Stapleton

Diefenbach-Jagger

Ure

Michelangeli

V.P.

Simmons

H.A.

et al., Parathyroid hormone-related protein of malignancy: active synthetic fragments, Science 238 (1987), 1568–1570.

17.

Seitz

P.K.

Thomas

M.L.

Selvanayagam

Rajaraman

and Cooper

C.W.

, Widespread expression of the parathyroid hormone-related peptide and PTH/PTHrP receptor genes in intestinal epithelial cells, Lab Invest 73 (1995), 864–870.

18.

Edwards

R.C.

Ratcliffe

W.A.

Walls

Morrison

J.M.

Ratcliffe

J.G.

Holder

and Bundred

N.J.

, Parathyroid hormone-related protein (PTHrP) in breast cancer and benign breast tissue, Eur J Cancer 31A (1995), 334–339.

19.

Yang

Guo

Divieti

and Bringhurst

F.R.

, Parathyroid hormone activates PKC-delta and regulates osteoblastic differentiation via a PLC-independent pathway, Bone 38 (2006), 485–496.

20.

Kondo

Guo

and Bringhurst

F.R.

, Cyclic adenosine monophosphate/protein kinase A mediates parathyroid hormone/parathyroid hormone-related protein receptor regulation of osteoclastogenesis and expression of RANKL and osteoprotegerin mRNAs by marrow stromal cells, J Bone Miner Res 17 (2002), 1667–1679.

21.

Takasu

and Bringhurst

F.R.

, Type-1 parathyroid hormone (PTH)/PTH-related peptide (PTHrP) receptors activate phospholipase C in response to carboxyl-truncated analogs of PTH(1-34), Endocrinology 139 (1998), 4293–4299.

22.

Frazier-Bowers

S.A.

Simmons

Wright

J.T.

Proffit

W.R.

and Ackerman

J.L.

, Primary failure of eruption and PTH1R: the importance of a genetic diagnosis for orthodontic treatment planning, Am J Orthod Dentofacial Orthop 137 (2010), 160 e1-7; discussion 160-1.

23.

Stellzig-Eisenhauer

Decker

Meyer-Marcotty

Rau

Fiebig

B.S.

Kress

Saar

Ruschendorf

Hubner

Grimm

Witt

and Weber

B.H.

, Primary failure of eruption (PFE)-clinical and molecular genetics analysis, J Orofac Orthop 71 (2010), 6–16.

24.

Yang

Hoang

B.H.

Kubo

Kawano

Chou

Sowers

Huvos

A.G.

Meyers

P.A.

Healey

J.H.

and Gorlick

, Over-expression of parathyroid hormone Type 1 receptor confers an aggressive phenotype in osteosarcoma, Int J Cancer 121 (2007), 943–954.

25.

Hoey

R.P.

Sanderson

Iddon

Brady

Bundred

N.J.

and Anderson

N.G.

, The parathyroid hormone-related protein receptor is expressed in breast cancer bone metastases and promotes autocrine proliferation in breast carcinoma cells, Br J Cancer 88 (2003), 567–573.

26.

Long

R.G.

Meinhard

Skinner

R.K.

Varghese

Wills

M.R.

and Sherlock

, Clinical, biochemical, and histological studies of osteomalacia, osteoporosis, and parathyroid function in chronic liver disease, Gut 19 (1978), 85–90.

27.

Chen

Cheung

S.T.

Fan

S.T.

Barry

Higgins

Lai

K.M.

Dudoit

I.O.

Van De Rijn

Botstein

and Brown

P.O.

, Gene expression patterns in human liver cancers, Mol Biol Cell 13 (2002), 1929–1939.

28.

Roessler

Jia

H.L.

Budhu

Forgues

Q.H.

Lee

J.S.

Thorgeirsson

S.S.

Sun

Tang

Z.Y.

Qin

L.X.

and Wang

X.W.

, A unique metastasis gene signature enables prediction of tumor relapse in early-stage hepatocellular carcinoma patients, Cancer Res 70 (2010), 10202–10212.

29.

Wurmbach

Chen

Y.B.

Khitrov

Zhang

Roayaie

Schwartz

Fiel

Thung

Mazzaferro

Bruix

Bottinger

Friedman

Waxman

and Llovet

J.M.

, Genome-wide molecular profiles of HCV-induced dysplasia and hepatocellular carcinoma, Hepatology 45 (2007), 938–947.

30.

Mas

V.R.

Maluf

D.G.

Archer

K.J.

Yanek

Kong

Kulik

Freise

C.E.

Olthoff

K.M.

Ghobrial

R.M.

McIver

and Fisher

, Genes involved in viral carcinogenesis and tumor initiation in hepatitis C virus-induced hepatocellular carcinoma, Mol Med 15 (2009), 85–94.

31.

Chen

Zheng

Baade

P.D.

Zhang

Zeng

Bray

Jemal

X.Q.

and He

, Cancer statistics in China, 2015, CA Cancer J Clin 66 (2016), 115–132.

32.

Sultan e

Sharif

and Shah

A.A.

, Parathryoid hormone related peptide causing hypercalcaemia in a patient with hepatocellular carcinoma, J Pak Med Assoc 63 (2013), 263–264.

33.

Newman

N.B.

Jabbour

S.K.

Hon

J.D.

Berman

J.J.

Malik

Carpizo

and Moss

R.A.

, Hepatocellular Carcinoma Without Cirrhosis Presenting With Hypercalcemia: Case Report and Literature Review, J Clin Exp Hepatol 5 (2015), 163–166.

34.

Kim

E.K.

Kim

J.S.

Shin

K.C.

Lee

G.T.

Han

C.J.

Kim

S.B.

and Ku

Y.H.

, Complete Tumor Resection for a Hepatocellular Carcinoma Secreting Parathyroid Hormone-related Peptide, Korean J Gastroenterol 66 (2015), 122–126.

35.

Yen

T.C.

Hwang

S.J.

Wang

C.C.

Lee

S.D.

and Yeh

S.H.

, Hypercalcemia and parathyroid hormone-related protein in hepatocellular carcinoma, Liver 13 (1993), 311–315.

36.

Rouleau

M.F.

Warshawsky

and Goltzman

, Parathyroid hormone binding in vivo to renal, hepatic, and skeletal tissues of the rat using a radioautographic approach, Endocrinology 118 (1986), 919–931.

37.

Pillai

and Zull

J.E.

, Production of biologically active fragments of parathyroid hormone by isolated Kupffer cells, J Biol Chem 261 (1986), 14919–14923.

38.

Segre

G.V.

Perkins

A.S.

Witters

L.A.

and Potts

, Jr., Metabolism of parathyroid hormone by isolated rat Kupffer cells and hepatocytes, J Clin Invest 67 (1981), 449–457.

39.

Martin

Hruska

Greenwalt

Klahr

and Slatopolsky

, Selective uptake of intact parathyroid hormone by the liver: differences between hepatic and renal uptake, J Clin Invest 58 (1976), 781–788.

40.

P.W.

Goradia

Russell

M.R.

Chalk

A.M.

Milley

K.M.

Baker

E.K.

Danks

J.A.

Slavin

J.L.

Walia

Crimeen-Irwin

Dickins

R.A.

Martin

T.J.

and Walkley

C.R.

, Knockdown of PTHR1 in osteosarcoma cells decreases invasion and growth and increases tumor differentiation in vivo , Oncogene 34 (2015), 2922–2933.

Decreased expression of PTH1R is a poor prognosis in hepatocellular carcinoma

Abstract

BACKGROUND AND AIM:

METHODS:

RESULTS:

CONCLUSIONS:

Keywords

1. Introduction

2. Materials and methods

2.1 Oncomine database analysis

2.2 Patients and tissue samples

2.4 Statistical analysis

3.1 Analysis of PTH1R, PTH, PTHrP expression based on Oncomine database

Table 1 Expression of PTH1R in non-tumorous liver tissues

3.4 Survival analysis

Footnotes

Acknowledgments

Conflict of interest

References

Table 1
Expression of PTH1R in non-tumorous liver tissues