MRE11A and SKP2 genes are associated with the increased cytotoxicity induced by the synergistic effects of cisplatin and gemcitabine in bladder cancer cells

TRIM24 is critical for the cellular response to DNA double-strand breaks through regulating the recruitment of MRN complex

The MRE11-RAD50-NBS1 (MRN) complex plays a crucial role in DNA double-strand breaks (DSBs) sensing and initiation of signaling cascades. However, the precise mechanisms by which the recruitment of MRN complex is regulated has yet to be elucidated. Here, we identified TRIpartite motif-containing protein 24 (TRIM24), a protein considered as an oncogene overexpressed in cancers, as a novel signaling molecule in response to DSBs. TRIM24 is essential for DSBs-induced recruitment of MRN complex and activation of downstream signaling. In the absence of TRIM24, MRN mediated DSBs repair is remarkably diminished. Mechanistically, TRIM24 is phosphorylated by ataxia-telangiectasia mutated (ATM) and then recruited to DSBs sites, facilitating the accumulation of the MRN components to chromatin. Depletion of TRIM24 sensitizes human hepatocellular carcinoma cells to cancer therapy agent-induced apoptosis and retards the tumor growth in a subcutaneous xenograft tumor mouse model. Together, our data reveal a novel function of TRIM24 in response to DSBs through regulating the MRN complex, which suggests that TRIM24 may be a potential therapeutic molecular target for tumor treatment.

FAM60A promotes cisplatin resistance in lung cancer cells by activating SKP2 expression

Cisplatin is a widely used chemotherapeutic drug in lung cancer treatment. Most cancer patients eventually develop cisplatin resistance, resulting in a poor prognosis. Previously, we identified a novel marker, family with sequence similarity 60A (FAM60A), that was responsible for resistance in cisplatin-resistant human lung adenocarcinoma A549 (A549/DDP) cells. Here, we investigated the biological effects of FAM60A in A549/DDP cells and explored the underlying molecular mechanisms to understand its functional role in cisplatin resistance. Real-time quantitative PCR and western blot analysis were used to determine the expression levels of FAM60A in A549/DDP cells. FAM60A and SKP2 were knockdown with small-interfering RNA (siRNA). Cancer cell viability was analyzed with flow cytometry. The mRNA and protein expression levels of FAM60A increased significantly and dose-dependently in A549/DDP cells following cisplatin treatment. FAM60A overexpression up-regulated MDR1 expression, inhibited caspase 3, cleaved-caspase 3, and caspase 8 expression, and prevented cancer cell death. Microarray analysis of cells transfected with siRNA against the FAM60A transcript and control samples showed that SKP2 expression was positively regulated by FAM60A. SKP2 knockdown using a short-hairpin RNA reversed the functions induced by FAM60A. These results suggest that overexpression of FAM60A in A549/DDP cells led to SKP2 upregulation and enhanced cisplatin resistance in cancer cells. These provide new insights into chemoresistance and may contribute to reversing cisplatin resistance during lung cancer treatment.

DNA damage response and repair in osteosarcoma: Defects, regulation and therapeutic implications

Osteosarcoma (OS) is the most common primary bone malignancy in children and adolescents which has the survival rate of 20% in its advanced stages. Osteosarcomas are mostly resistance to our common treatments. DNA damage response (DDR) is a specialized multistep process containing abundant proteins which are necessary for the survival of any cell and organism. DDR machinery detects a diversity of DNA lesions and inhibits the cell cycle progression if these lesions are not repairable. DDR is involved in aging, age-related diseases, and cancer. In recent years, DDR inhibitors have gained the attention of researches due to their potentials in offering novel therapeutic targets and improving the response of many cancers to either chemo- or radio-therapy. In this regard, we tried to gather a great body of evidence about the role of DDR ingredients in osteosarcoma's initiation/progression, prognosis, and treatment.

MRE11-RAD50-NBS1 complex alterations and DNA damage response: implications for cancer treatment

Genome instability is a hallmark of cancer cells and can be accelerated by defects in cellular responses to DNA damage. This feature of malignant cells opens new avenues for tumor targeted therapy. MRE11-RAD50-NBS1 complex plays a crucial role in sensing and repair of DNA damage. Through interacting with other important players of DNA damage response, MRE11-RAD50-NBS1 complex is engaged in various DNA damage repair pathways. Mutations in any member of this complex may lead to hypersensitivity to genotoxic agents and predisposition to malignancy. It is assumed that the defects in the complex may contribute to tumorigenesis and that treatments targeting the defect may be beneficial to cancer patients. Here, we summarized the recent research findings of the role of MRE11-RAD50-NBS1 complex in tumorigenesis, cancer treatment and discussed the potential approaches of targeting this complex to treat cancer.

Synergistic and Pharmacotherapeutic Effects of Gemcitabine and Cisplatin Combined Administration on Biliary Tract Cancer Cell Lines

Gemcitabine (GEM) and cisplatin (CDDP) combination therapy (GC) is the standard chemotherapy for advanced biliary tract cancer (BTC); however, its pharmacotherapeutic efficacy remains unclear. To investigate the effects of GC, we selected 11 from 17 BTC cell lines, according to their GEM sensitivity, to be assessed using the MTS assay. The presence of synergistic effects of GC was determined using the Bliss additivism model (BM) and the combination index (CI) at a GEM:CDDP molar ratio of 7:1; this ratio was based on the respective human renal clearances of the two drugs. The pharmacotherapeutic effects were evaluated by comparing the IC50 values for administrations of GEM alone and GC in combination. All cell lines showed synergistic effects when analyzed using the BM. Based on the CI values, strong synergism, synergism, and additive effects were seen in four, five, and two cell lines, respectively. For all four GEM-resistant cell lines, on which GC had strong synergistic effects, the pharmacotherapeutic effects of GC were disappointing, with all IC50 values > 1 µM. For the GEM-effective cell lines, on which GC had synergistic or additive effects, the IC50 values were all <1 µM, and the differences were small between the IC50s for administration of GEM alone and GC in combination. Our results suggest that GC has synergistic effects on BTC cell lines but that its pharmacotherapeutic effects are inadequate.