X-ray repair cross-complementing protein 1 (XRCC1) loss promotes β-lapachone -induced apoptosis in pancreatic cancer cells

PARP inhibitor response is enhanced in prostate cancer when XRCC1 expression is reduced

Prostate cancer (PCa) is the second most common cancer worldwide and the fifth leading cause of cancer-related deaths among men. The emergence of metastatic castration-resistant prostate cancer (mCRPC) after androgen deprivation therapy (ADT) exemplifies the complex disease management for PCa. PARP inhibitors (PARPis) are being tested to treat mCRPC in tumors with defective homologous recombination repair (HRR) to address this complexity. However, increasing resistance towards PARPi in HRR-deficient patients and the low percentage of HRR-defective mCRPC patients requires the identification of new genes whose deficiency can be exploited for PARPi treatment. XRCC1 is a DNA repair protein critical in the base excision repair (BER) and single strand break repair (SSBR) pathways. We analyzed PCa patients' cohorts and found that XRCC1 expression varies widely, with many patients showing low XRCC1 expression. We created XRCC1 deficiency in PCa models to examine PARPi sensitivity. XRCC1 loss conferred hypersensitivity to PARPi by promoting the accumulation of DNA double-strand breaks, increasing cell-cycle arrest, and inducing apoptosis. We confirmed that XRCC1 expression correlated with PARPi sensitivity using a doxycycline-inducible system. Therefore, we conclude that XRCC1 expression level predicts response to PARPi, and the clinical utility of PARPi in PCa can extend to low XRCC1 expressing tumors.

β-lapachone suppresses carcinogenesis of cervical cancer via interaction with AKT1

Introduction

Cervical cancer is one of the most prevalent malignant tumors affecting women worldwide, and affected patients often face a poor prognosis due to its high drug resistance and recurrence rates. β-lapachone, a quinone compound originally extracted from natural plants, is an antitumor agent that specifically targets NQO1.

Methods

CC cells were treated with varying concentrations of β-lapachone to examine its effects on glucose metabolism, proliferation, metastasis, angiogenesis, and EMT in vitro. The targets and action pathways of β-lapachone were identified using network pharmacology and molecular docking, with KEGG pathway enrichment analysis. Its effects and toxicity were verified in vivo using a nude mouse xenograft model.

Results

β-lapachone significantly inhibited the proliferation and metastasis of cervical cancer cells by regulating glucose metabolism, reducing tumor angiogenesis, and suppressing epithelial-mesenchymal transition (EMT) in cells with high NQO1 expression. Furthermore, we identified the inactivation of the PI3K/AKT/mTOR pathway as the key mechanism underlying these effects. AKT1 was identified as a potential target of β-lapachone in modulating glucose metabolism and EMT in cervical cancer cells.

Conclusion

These findings suggest that β-lapachone inhibits the malignant progression of cervical cancer by targeting AKT1 to regulate glucose metabolism in NQO1-overexpressing cells, providing a theoretical basis for developing novel therapeutic strategies for cervical cancer.

XRCC1 is linked to poor prognosis in adenocarcinoma of the esophagogastric junction after radiotherapy: transcriptome and alternative splicing events analysis

PURPOSE

This study aimed to (i) investigate the relationship between X-ray repair cross-complementing protein 1 gene (XRCC1) and prognosis in patients with adenocarcinoma of the esophagogastric junction (AEG), and (ii) analyze the roles of XRCC1 in human gastric adenocarcinoma (AGS) cells following X-ray radiation.

METHODS

A total of 46 AEG patients were enrolled and examined for XRCC1 protein by immunohistochemistry. XRCC1 was knocked down in AGS cells by transfection, and AGS cells were subsequently exposed to 6 Gy of X-ray radiation. XRCC1 mRNA and protein expression was examined via quantitative real-time PCR (qRT-PCR) and Western blot analysis. The apoptosis of AGS cells was examined by flow cytometer. RNA-sequencing technology was used to identified differentially expressed genes and alternative splicing events following XRCC1 knockdown and radiation exposure.

RESULTS

XRCC1 positivity was strongly associated with distant metastasis, pathological tumor-node-metastasis (pTNM) classification, and radiotherapy resistance in AEG patients. A significant difference in progression-free survival was observed between AEG patients with low and high XRCC1 protein expression. The knockdown of XRCC1 notably exacerbated the effects of X-ray radiation on apoptosis in AGS cells. Additionally, X-ray radiation modified the expression of genes related to apoptosis and immune response in XRCC1-knockdown AGS cells. Furthermore, the generation of splice variants was influenced by XRCC1 knockdown in AGS cells.

CONCLUSION

XRCC1 may serve as a key oncogene that elucidates the role of alternative splicing events in the progression of AEG following X-ray treatment.

X-ray cross-complementing family: the bridge linking DNA damage repair and cancer

Genomic instability is a common hallmark of human tumours. As a carrier of genetic information, DNA is constantly threatened by various damaging factors that, if not repaired in time, can affect the transmission of genetic information and lead to cellular carcinogenesis. In response to these threats, cells have evolved a range of DNA damage response mechanisms, including DNA damage repair, to maintain genomic stability. The X-ray repair cross-complementary gene family (XRCC) comprises an important class of DNA damage repair genes that encode proteins that play important roles in DNA single-strand breakage and DNA base damage repair. The dysfunction of the XRCC gene family is associated with the development of various tumours. In the context of tumours, mutations in XRCC and its aberrant expression, result in abnormal DNA damage repair, thus contributing to the malignant progression of tumour cells. In this review, we summarise the significant roles played by XRCC in diverse tumour types. In addition, we discuss the correlation between the XRCC family members and tumour therapeutic sensitivity.

Tailored Beta-Lapachone Nanomedicines for Cancer-Specific Therapy

Nanotechnology shows the power to improve efficacy and reduce the adverse effects of anticancer agents. As a quinone-containing compound, beta-lapachone (LAP) is widely employed for targeted anticancer therapy under hypoxia. The principal mechanism of LAP-mediated cytotoxicity is believed due to the continuous generation of reactive oxygen species with the aid of NAD(P)H: quinone oxidoreductase 1 (NQO1). The cancer selectivity of LAP relies on the difference between NQO1 expression in tumors and that in healthy organs. Despite this, the clinical translation of LAP faces the problem of narrow therapeutic window that is challenging for dose regimen design. Herein, the multifaceted anticancer mechanism of LAP is briefly introduced, the advance of nanocarriers for LAP delivery is reviewed, and the combinational delivery approaches to enhance LAP potency in recent years are summarized. The mechanisms by which nanosystems boost LAP efficacy, including tumor targeting, cellular uptake enhancement, controlled cargo release, enhanced Fenton or Fenton-like reaction, and multidrug synergism, are also presented. The problems of LAP anticancer nanomedicines and the prospective solutions are discussed. The current review may help to unlock the potential of cancer-specific LAP therapy and speed up its clinical translation.

The Role of 8-oxoG Repair Systems in Tumorigenesis and Cancer Therapy

Tumorigenesis is highly correlated with the accumulation of mutations. The abundant and extensive DNA oxidation product, 8-Oxoguanine (8-oxoG), can cause mutations if it is not repaired by 8-oxoG repair systems. Therefore, the accumulation of 8-oxoG plays an essential role in tumorigenesis. To avoid the accumulation of 8-oxoG in the genome, base excision repair (BER), initiated by 8-oxoguanine DNA glycosylase1 (OGG1), is responsible for the removal of genomic 8-oxoG. It has been proven that 8-oxoG levels are significantly elevated in cancer cells compared with cells of normal tissues, and the induction of DNA damage by some antitumor drugs involves direct or indirect interference with BER, especially through inducing the production and accumulation of reactive oxygen species (ROS), which can lead to tumor cell death. In addition, the absence of the core components of BER can result in embryonic or early post-natal lethality in mice. Therefore, targeting 8-oxoG repair systems with inhibitors is a promising avenue for tumor therapy. In this study, we summarize the impact of 8-oxoG accumulation on tumorigenesis and the current status of cancer therapy approaches exploiting 8-oxoG repair enzyme targeting, as well as possible synergistic lethality strategies involving exogenous ROS-inducing agents.

Transcription-associated DNA DSBs activate p53 during hiPSC-based neurogenesis

Neurons are overproduced during cerebral cortical development. Neural progenitor cells (NPCs) divide rapidly and incur frequent DNA double-strand breaks (DSBs) throughout cortical neurogenesis. Although half of the neurons born during neurodevelopment die, many neurons with inaccurate DNA repair survive leading to brain somatic mosaicism. Recurrent DNA DSBs during neurodevelopment are associated with both gene expression level and gene length. We used imaging flow cytometry and a genome-wide DNA DSB capture approach to quantify and map DNA DSBs during human induced pluripotent stem cell (hiPSC)-based neurogenesis. Reduced p53 signaling was brought about by knockdown (p53KD); p53KD led to elevated DNA DSB burden in neurons that was associated with gene expression level but not gene length in neural progenitor cells (NPCs). Furthermore, DNA DSBs incurred from transcriptional, but not replicative, stress lead to p53 activation in neurotypical NPCs. In p53KD NPCs, DNA DSBs accumulate at transcription start sites of genes that are associated with neurological and psychiatric disorders. These findings add to a growing understanding of how neuronal genome dynamics are engaged by high transcriptional or replicative burden during neurodevelopment.