[Advances of DNA damage repair and Cisplatin resistance mechanisms in lung cancer]

The mechanism and clinical application of DNA damage repair inhibitors combined with immune checkpoint inhibitors in the treatment of urologic cancer

Urologic cancers such as kidney, bladder, prostate, and uroepithelial cancers have recently become a considerable global health burden, and the response to immunotherapy is limited due to immune escape and immune resistance. Therefore, it is crucial to find appropriate and effective combination therapies to improve the sensitivity of patients to immunotherapy. DNA damage repair inhibitors can enhance the immunogenicity of tumor cells by increasing tumor mutational burden and neoantigen expression, activating immune-related signaling pathways, regulating PD-L1 expression, and reversing the immunosuppressive tumor microenvironment to activate the immune system and enhance the efficacy of immunotherapy. Based on promising experimental results from preclinical studies, many clinical trials combining DNA damage repair inhibitors (e.g., PARP inhibitors and ATR inhibitors) with immune checkpoint inhibitors (e.g., PD-1/PD-L1 inhibitors) are underway in patients with urologic cancers. Results from several clinical trials have shown that the combination of DNA damage repair inhibitors with immune checkpoint inhibitors can improve objective rates, progression-free survival, and overall survival (OS) in patients with urologic tumors, especially in patients with defective DNA damage repair genes or a high mutational load. In this review, we present the results of preclinical and clinical trials of different DNA damage repair inhibitors in combination with immune checkpoint inhibitors in urologic cancers and summarize the potential mechanism of action of the combination therapy. Finally, we also discuss the challenges of dose toxicity, biomarker selection, drug tolerance, drug interactions in the treatment of urologic tumors with this combination therapy and look into the future direction of this combination therapy.

NCAPG2 Maintains Cancer Stemness and Promotes Erlotinib Resistance in Lung Adenocarcinoma

Simple Summary

This study investigated the relationship between erlotinib resistance and stemness in lung adenocarcinoma. NCAPG2 was identified as an erlotinib resistance gene and maintained the stemness of lung adenocarcinoma.

Abstract

Erlotinib is a highly specific and reversible epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), but resistance inevitably develops as the disease progresses. Erlotinib resistance and cancer stem cells (CSCs) are poor factors hindering the prognosis of patients with lung adenocarcinoma (LUAD). Although studies have shown that erlotinib resistance and CSCs can jointly promote cancer development, the mechanism is currently unclear. Here, we investigated the potential biomarker and molecular mechanism of erlotinib resistance and cancer stemness in LUAD. An erlotinib resistance model based on four genes was constructed from The Cancer Genome Atlas (TCGA), the GEO database, the Cancer Cell Line Encyclopedia (CCLE), and the Genomics of Drug Sensitivity in Cancer (GDSC). Through multiple bioinformatic analyses, NCAPG2 was identified as a key gene for erlotinib resistance and stemness in LUAD. Further in vitro experiments demonstrated that NCAPG2 maintains stemness and contributes to erlotinib resistance in LUAD. In summary, NCAPG2 plays a vital role in stemness and erlotinib resistance in LUAD.

Molecular mechanisms of chemo- and radiotherapy resistance and the potential implications for cancer treatment

Cancer is a leading cause of death worldwide. Surgery is the primary treatment approach for cancer, but the survival rate is very low due to the rapid progression of the disease and presence of local and distant metastasis at diagnosis. Adjuvant chemotherapy and radiotherapy are important components of the multidisciplinary approaches for cancer treatment. However, resistance to radiotherapy and chemotherapy may result in treatment failure or even cancer recurrence. Radioresistance in cancer is often caused by the repair response to radiation-induced DNA damage, cell cycle dysregulation, cancer stem cells (CSCs) resilience, and epithelial-mesenchymal transition (EMT). Understanding the molecular alterations that lead to radioresistance may provide new diagnostic markers and therapeutic targets to improve radiotherapy efficacy. Patients who develop resistance to chemotherapy drugs cannot benefit from the cytotoxicity induced by the prescribed drug and will likely have a poor outcome with these treatments. Chemotherapy often shows a low response rate due to various drug resistance mechanisms. This review focuses on the molecular mechanisms of radioresistance and chemoresistance in cancer and discusses recent developments in therapeutic strategies targeting chemoradiotherapy resistance to improve treatment outcomes.

Pharmacological Effects of Verticine: Current Status

Verticine is the major bioactive constituent of Fritillaria as a kind of Traditional Chinese Medicine. Pharmacological researches have reported various benefits of verticine, including anticancer, anti-inflammatory, protecting against acute lung injury, tracheobronchial relaxation, antitussive, expectorant, sedative, and analgesic activities, in addition to inhibiting proliferation of cultured orbital fibroblast, angiotensin converting enzyme (ACE), and acetylcholinesterase (AChE) and inhibiting hERG potassium channels. The underlying mechanisms of verticine are still under investigation. This review will comprehensively summarize the metabolism, biological activities, and possible mechanism of verticine.

[ole of AGGF1 in DNA damage repair and modulating chemotherapy resistance in human colon cancer cells in vitro]

OBJECTIVE

To investigate the role of AGGF1 in DNA damage repair and modulating chemotherapy resistance in human colon cancer cells.

METHODS

Cisplatin-induced human colon cancer HCT116 cells transfected with AGGF1 siRNA and siNC via Lipofectamine 2000 were examined for AGGF1, γH2AX and pNBS1 expressions using Western blotting. Immunofluorescence analysis was used to detect the recruitment of phosphorylated γH2AX and AGGF1 at the site of cisplatin-induced double-strand DNA breaks, and MTS method was used to investigate the proliferation of the damaged cells. Immunohistochemical method was used to detect the expression level of AGGF1 in human colon cancer and adjacent normal tissues.

RESULTS

Western blotting showed that AGGF1 expression was significantly down-regulated in HCT116 cells after cisplatin exposure, and transfection withAGGF1 siRNAobviously inhibited the expression of phosphorylated γH2AX and NBS1. Immunofluorescence assay showed the co-localization of AGGF1 and γH2AX. Down-regulation of AGGF1 mediated by siRNA obviously increased the chemosensitivity of the cells (P < 0.01). In the clinical specimens, AGGF1 was found to be overexpressed in colon cancer tissues as compared with the adjacent normal tissues (P < 0.01), suggesting its association with the malignant phenotype of the tumor.

CONCLUSIONS

Down-regulation of AGGF1 inhibits DNA damage repair and increases the chemosensitivity in colon cancer cells possibly in relation with the suppressed phosphorylation of NBS1.

[Effect of Src tyrosine kinase inhibition on the drug-resistance as well as MDR1 and LRP expression of the human cis-platinum-resistant lung cancer cell line A549/DDP]

BACKGROUND

The aim of this study is to investigate the effect of Src tyrosine kinase inhibition on the drug-resistance as well as the expression of multidrug resistance 1 (MDR1) and lung resistance-related protein (LRP) of the human cis-platinum-resistant lung cancer cell line A549/DDP.

METHODS

4-Anilinoquirazoline was used to inhibit Src tyrosine kinase activity in A549/DDP. Western blot analysis was used to detect the Src tyrosine kinase activity. CellTiter-Glo assay was used to detect the drug sensitivity of tumor cells. Flow cytometry was used to detect the intracellular Rh-123 content. Western blot and real-time PCR assay were used to detect the expression of tumor MDR1 and LRP.

RESULTS

4-Anilinoquirazoline can down-regulate the cellular Src tyrosine kinase activity in A549/DDP. After treatment with 2.5 μM and 10 μM of 4-anilinoquirazoline, the cells became more sensitive to the drug and the reversal folds (RFs) of tumor cell sensitivity to the drug were 1.59- and 2.10-fold, respectively. The intracellular content of Rh-123 improved by 1.21- and 1.59-fold, respectively. The mRNA levels of MDR1 were 53.8% and 27.5% of the control, respectively. The mRNA level of LRP was 59.3% and 21.4% of the control, respectively. The expression of MDR1 and LRP protein significantly decreased.

CONCLUSIONS

The inhibition of Src tyrosine kinase activity in A549/DDP cells can reverse multi-drug resistance and increase the sensitivity of the cells to the drug. The mechanism may be related to the down-regulation of cellular MDR1 and LRP.