Boronophenylalanine-Mediated Boron Neutron Capture Therapy Confers Selective Killing of Cervical Cancer by Exploiting DNA Repair Deficiency

Abstract

Objective:

Boron neutron capture therapy (BNCT) is an emerging binary targeted radiotherapy modality. This study evaluates the therapeutic potential of boronophenylalanine (BPA)-mediated BNCT in cervical cancer and to elucidate its underlying molecular mechanisms.

Methods:

A comprehensive set of in vitro and in vivo approaches was employed using cervical cancer cell lines (HeLa, SiHa) and normal cervical epithelial cells (H8). The experimental techniques included clonogenic assays, flow cytometry, Western blotting, immunohistochemistry, and xenograft mouse models to assess cytotoxicity, boron uptake, DNA damage response, apoptosis, and therapeutic efficacy.

Results:

Cervical cancer cells exhibited significantly higher L-type amino acid transporter 1 (LAT1) expression compared with normal controls, which correlated with enhanced BPA uptake. BPA-BNCT induced profound, dose-dependent cell death and reversed the conventional radiotherapeutic sensitivity profiles between cancer and normal cells. Notably, BNCT demonstrated selective cytotoxicity across different pathological subtypes of cervical cancer, with enhanced therapeutic efficacy observed in adenocarcinoma—a subtype typically resistant to conventional radiotherapy. Mechanistically, BNCT triggered complex DNA double-strand breaks that overwhelmed cellular repair mechanisms, despite robust activation of both homologous recombination (via RAD51) and nonhomologous end joining (via KU70/80). This irreparable DNA damage resulted in G2/M phase arrest and activation of the mitochondrial apoptosis pathway. In xenograft models, BPA-BNCT achieved significant tumor growth suppression and substantially prolonged survival, while maintaining a wide therapeutic window and showing no evidence of systemic toxicity.

Conclusions:

BPA-BNCT exerts potent and selective antitumor effects against cervical cancer through a dual mechanism: LAT1-mediated boron delivery ensures tumor specificity, while the resulting high-linear energy transfer radiation induces DNA damage that capitalizes on the inherent limitations of the tumor cells’ DNA repair capacity, leading to catastrophic cell death. The therapy demonstrates a distinct advantage in treating adenocarcinoma subtypes, which are typically less responsive to conventional radiotherapy. These findings provide robust preclinical evidence supporting BNCT as a promising therapeutic approach, particularly for radiotherapy-resistant cervical adenocarcinoma.