The bromodomain and extra-terminal domain inhibitor JQ1 synergistically sensitizes human colorectal cancer cells to topoisomerase I inhibitors through repression of Mre11-mediated DNA repair pathway.

Camptothecin (CPT) and its derivatives, irinotecan and topotecan are specific topoisomerase I (Top1) inhibitors and potent anticancer drugs. Mechanistically, they induce DNA double-strand breaks (DSBs). Although CPT is an effective chemotherapeutic agent used in the management of advanced colorectal cancer, there exist associated side effects. Herein, we aimed to establish novel drug combinations that can effectively aid in managing the CPT-related side effects. Besides, bromodomain and extra-terminal domain (BET) inhibitors have proved as promising drugs that target epigenetic mechanisms in various cancers, they alter DNA repair processes, hence are a potential candidate for CPT synthetic lethality. A novel BET inhibitor JQ1 synergized with CPT, exerted antiproliferative effects. Through cell cycle analyses and apoptosis assays, we revealed that a combination of CPT and JQ1 induces subG1-phase arrest and enhances cell apoptosis. This combination increased the intensity of γ-H2AX staining, a specific marker of DSBs. Moreover, colorectal cancer cells highly expressing Top1 showed greater sensitivity to JQ1, which was lowered through the lentiviral shRNA-mediated knockdown of Top1. JQ1, combined with CPT, impeded the recruitment of the Mre11-mediated MRN complex. Finally, JQ1 enhanced the in vivo sensitivity of tumors to CPT without inducing toxicity. These results demonstrate that a combination of BET inhibitor with Top1 inhibitor is safe and exerts positive chemotherapeutic effects in colorectal cancer.

miR-124 Intensified Oxaliplatin-Based Chemotherapy by Targeting CAPN2 in Colorectal Cancer.

Our previous study demonstrated that miR-124 was downregulated in colorectal cancer (CRC) compared with normal mucosa, and the downregulated expression of miR-124 was an independent prognostic factor in CRC patients. However, the function of miR-124 in CRC patients treated with chemotherapy is currently unclear. The aim of this study was to determine the miR-124 expression and its regulative role in oxaliplatin (L-OHP)-based chemotherapy of CRC patients. We observed that low miR-124 expression was correlated with worse overall survival (OS) in the 220 patients who received postoperative chemotherapy of 5-fluorouracil [5-FU]+leucovorin+L-OHP (FOLFOX) or capecitabine+L-OHP (XELOX). miR-124 overexpression promoted L-OHP-induced, but not 5-FU-induced, cytotoxicity and apoptosis in HT29 and SW480 cells. CAPN2 was a direct target of miR-124, and its protein expression was reduced by forced expression of miR-124. miR-124 inhibited tumorigenesis and promoted OS of mice bearing xenograft tumors, especially upon L-OHP treatment. miR-124 also promoted L-OHP-induced apoptosis and restrained CAPN2 protein expression in xenograft tumors. Our results suggest that miR-124 could be considered as both a predictor of L-OHP-based chemotherapy for personalized treatment and a therapeutic target for CRC.

The expression of SOX9, Tiam1, and PTEN is correlated with angiogenesis and prognosis in gastric cancer.

BACKGROUND: With a high rate of metastasis and recurrence, gastric cancer (GC), a common malignant tumor, often has a poor prognosis. GC tissues have abnormal expressions of the Sry-related HMG-box family of transcription factors (SOX9), T-lymphoma invasion and metastasis-inducing factor 1 (Tiam1), and phosphatase and tensin homolog deleted on chromosome ten (PTEN). Meanwhile, vascular endothelial growth factor (VEGF) have been reported to play an important role in tumor angiogenesis. This study aimed to analyze the correlation of SOX9, Tiam1, and PTEN with angiogenesis and prognosis in GC. METHODS: A total of 90 patients who underwent GC surgery at our hospital between January 2017 and October 2018 were enrolled. The expressions of SOX9, Tiam1, PTEN, and VEGF in GC tissues and adjacent normal tissues were detected by immunohistochemistry and the differences were analyzed. Spearman's correlation coefficient was applied to analyze the relationship between the expression levels of SOX9, Tiam1, PTEN, and VEGF. The patients were followed-up. RESULTS: The positive expression rates of SOX9, Tiam1, PTEN, and VEGF in GC tissues were 75.56%, 61.11%, 52.22%, and 48.89%, respectively, compared with 6.67%, 4.44%, 97.78%, and 2.22%, respectively, in the adjacent normal tissues (P<0.05). Spearman's correlation analysis showed that the expression of SOX9 (r=0.349, P=0.001) and Tiam1 (Tiam1: r=0.370, P=0.000) in GC tissues was positively correlated with VEGF expression; however, PTEN was negatively correlated with VEGF (r=-0.311, P=0.000). There were no significant differences in SOX9, Tiam1, or PTEN expression in GC tissues from patients of different genders or ages (P>0.05). When the tumor was low differentiated, with lymph node metastasis or high TNM staging, the positive expression rates of SOX9 and Tiam1 were significantly increased (P<0.05), while the positive expression rate of PTEN was significantly decreased (P<0.05). The log-rank test results showed that the three-year survival rates of the groups with positive SOX9 (54.41%) and Tiam1 expression (49.09%) were significantly lower than those of the groups with negative SOX9 and Tiam1 expression (77.27% and 77.13%, respectively; P<0.05). The 3-year survival rate in the PTEN positive expression group was significantly higher than that of the PTEN negative expression group (76.60% vs. 41.80%; P<0.05). CONCLUSIONS: SOX9 and Tiam1 are highly expressed, in GC tissues while there is a low expression of PTEN. The expression levels of SOX9, Tiam1, and PTEN are all linearly correlated with VEGF expression, and they have important effects on angiogenesis and is closely related to the three-year survival rate of patients with GC.

Heterogeneous nuclear ribonucleoprotein L facilitates recruitment of 53BP1 and BRCA1 at the DNA break sites induced by oxaliplatin in colorectal cancer.

Although oxaliplatin is an effective chemotherapeutic drug for treatment of colorectal cancer (CRC), tumor cells can develop mechanisms to evade oxaliplatin-induced cell death and show high tolerance and acquired resistance to this drug. Heterogeneous nuclear ribonucleoprotein L (hnRNP L) has been proved to play a critical role in DNA repair during IgH class switch recombination (CSR) in B lymphocytes, while, its role in CRC and chemotherapeutic resistance remain unknown. Our study aims to uncover an unidentified mechanism of regulating DNA double-strand breaks (DSBs) by hnRNP L in CRC cells treated by oxaliplatin. In present study, we observed that knockdown of hnRNP L enhanced the level of DNA breakage and sensitivity of CRC cells to oxaliplatin. The expression of key DNA repair factors (BRCA1, 53BP1, and ATM) was unaffected by hnRNP L knockdown, thereby excluding the likelihood of hnRNP L mediation via mRNA regulation. Moreover, we observed that phosphorylation level of ATM changed oppositely to 53BP1 and BRCA1 in the CRC cells (SW620 and HCT116) which exhibit synergistic effect by oxaliplatin plus hnRNP L impairment. And similar phenomenon was observed in the foci formation of these critical repair factors. We also found that hnRNP L binds directly with these DNA repair factors through its RNA-recognition motifs (RRMs). Analysis of cell death indicated that the RRMs of hnRNP L are required for cell survival under incubation with oxaliplatin. In conclusion, hnRNP L is critical for the recruitment of the DNA repair factors in oxaliplatin-induced DSBs. Targeting hnRNP L is a promising new clinical approach that could enhance the effectiveness of current chemotherapeutic treatment in patients with resistance to oxaliplatin.

C-Reaction Protein Detection in Human Saliva by Nanoplasmonic Color Imaging.

A label-free and highly sensitive imaging sensor based on plasmonic-photonic interaction in a gold-titanium dioxidegold metal-insulator-metal (MIM) plasmonic nanocup array is reported. The sensor can detect proteins and exhibits superior performance in visible light sensing. This device enables very sensitive detection of an increase in superstrate refractive index based on changes in the red channel intensity of color imaging. Compared to other conventional plasmonic sensors, our device achieves transmission imaging detection by using normal white light and minimizes instrumentation requirement. In this study, we used the device to detect C-reaction protein (CRP) level in saliva, which is widely tested to help make clinical decisions in different diseases and disorders. The intensity imaging showed a good linear response between CRP concentration (from 5 to 100 ng/mL) and relative intensity change in the device. The lowest concentration of CRP that could be detected was 5 ng/mL. Moreover, it could achieve a positive detection in saliva from patients when the CRP level in serum was 3.2 µg/mL. Owing to the high performance of the MIM plasmonic nanocup array, the proposed device is promising for future portable optical sensing with visible light illumination and imaging.