miR-205 enhances radiation sensitivity of prostate cancer cells by impairing DNA damage repair through PKCε and ZEB1 inhibition

Deficiency of 15-LOX-1 Induces Radioresistance through Downregulation of MacroH2A2 in Colorectal Cancer

Despite the importance of radiation therapy, there are few radiation-related markers available for use in clinical practice. A larger catalog of such biomarkers is required to help clinicians decide when radiotherapy should be replaced with a patient-specific treatment. Arachidonate 15-lipoxygenase (15-LOX-1) enzyme is involved in polyunsaturated fatty acid metabolism. When colorectal cancer (CRC) cells were exposed to radiation, 15-LOX-1 was upregulated. To verify whether 15-LOX-1 protects against or induces DNA damage, we irradiated sh15-LOX-1 stable cells. We found that low 15-LOX-1 is correlated with radioresistance in CRC cells. These data suggest that the presence of 15-LOX-1 can be used as a marker for radiation-induced DNA damage. Consistent with this observation, gene-set-enrichment analysis based on microarray experiments showed that UV_RESPONSE was decreased in sh15-LOX-1 cells compared to shCon cells. Moreover, we discovered that the expression of the histone H2A variant macroH2A2 was sevenfold lower in sh15-LOX-1 cells. Overall, our findings present mechanistic evidence that macroH2A2 is transcriptionally regulated by 15-LOX-1 and suppresses the DNA damage response in irradiated cells by delaying H2AX activation.

miR-122-5p modulates the radiosensitivity of cervical cancer cells by regulating cell division cycle 25A (CDC25A)

Cervical cancer is one of the most common gynecological malignancies globally, Unfortunately, radiotherapy and chemotherapy are not effective at treating some cases of this disease, and the 5‐year survival rate is only 40–50%. Cell division cycle 25A (CDC25A) has been shown to induce radioresistance in a variety of tumor cells, but the role of CDC25A in the radioresistance of cervical cancer has not been fully elucidated. Here, we report that CDC25A is highly expressed and miR‐122‐5p lowly expressed in cervical cancer tissues and cells. The TargetScan database was used to predict CDC25A as a target of miR‐122‐5p, and the interactions between miR‐122‐5p and CDC25A were further confirmed by western blot, real‐time PCR and dual‐luciferase reporter assay. Under X‐ray irradiation, up‐regulation of CDC25A can promote the radiation resistance of cervical cancer cells, whereas overexpression of miR‐122‐5p or knockdown of CDC25A inhibits the survival and induces apoptosis of cervical cancer colonies. In conclusion, our data suggest that miR‐122‐5p enhances the radiosensitivity of cervical cancer cells by targeting CDC25A.

The miR-205-5p/BRCA1/RAD17 Axis Promotes Genomic Instability in Head and Neck Squamous Cell Carcinomas

Defective DNA damage response (DDR) is frequently associated with tumorigenesis. Abrogation of DDR leads to genomic instability, which is one of the most common characteristics of human cancers. TP53 mutations with gain-of-function activity are associated with tumors under high replicative stress, high genomic instability, and reduced patient survival. The BRCA1 and RAD17 genes encode two pivotal DNA repair proteins required for proper cell-cycle regulation and maintenance of genomic stability. We initially evaluated whether miR-205-5p, a microRNA (miRNA) highly expressed in head and neck squamous cell carcinoma (HNSCC), targeted BRCA1 and RAD17 expression. We found that, in vitro and in vivo, BRCA1 and RAD17 are targets of miR-205-5p in HNSCC, leading to inefficient DNA repair and increased chromosomal instability. Conversely, miR-205-5p downregulation increased BRCA1 and RAD17 messenger RNA (mRNA) levels, leading to a reduction in in vivo tumor growth. Interestingly, miR-205-5p expression was significantly anti-correlated with BRCA1 and RAD17 targets. Furthermore, we documented that miR-205-5p expression was higher in tumoral and peritumoral HNSCC tissues than non-tumoral tissues in patients exhibiting reduced local recurrence-free survival. Collectively, these findings unveil miR-205-5p’s notable role in determining genomic instability in HNSCC through its selective targeting of BRCA1 and RAD17 gene expression. High miR-205-5p levels in the peritumoral tissues might be relevant for the early detection of minimal residual disease and pre-cancer molecular alterations involved in tumor development.

miR-1271 inhibits growth, invasion and epithelial-mesenchymal transition by targeting ZEB1 in ovarian cancer cells

Objective

MicroRNA-1271 (miR-1271) has a role in suppressing cell growth, cell cycle and promoting cell apoptosis in many cancers. This research was to explore the great role of miR-1271 in ovarian cancer (OC).

Patients and Methods

RT-qPCR was utilized to evaluate the mRNA levels of miR-1271 and its target gene. The proliferative and invasive abilities were measured using Cell Counting Kit-8 and transwell assays. The overall survival rate of OC patients was assessed by Kaplan–Meier method.

Results

miR-1271 was downregulated in OC tissues, and downregulation of miR-1271 predicted a poor outcome of the OC patients. Zinc finger E-box binding homeobox 1 (ZEB1) was a target gene of miR-1271 and its expression was regulated by miR-1271 in OC. The expression of miR-1271 had a negative connection with the expression of ZEB1 in OC tissues. miR-1271 inhibited cell viability and invasion-mediated epithelial–mesenchymal transition in SKOV3 cells. ZEB1 reversed partial roles of miR-1271 on viability and invasion in OC.

Conclusion

miR-1271 inhibited cell proliferation and invasion-mediated EMT in OC. The newly identified miR-1271/ZEB1 axis provides novel insight into the pathogenesis of OC.

Insulinoma-associated protein 1 controls nasopharyngeal carcinoma to radiotherapy by modulating cyclin D1-dependent DNA repair machinery

Insulinoma-associated protein 1 (INSM1), a zinc finger transcriptional factor, is proven to be deregulated in several types of cancers. However, comprehension of the molecular mechanism of INSM1-mediated tumor progression remains poor. Here, we show that the radioresistant nasopharyngeal carcinoma (NPC) patients have higher expressions of INSM1 that correlated with poor prognosis. Genetic manipulation of INSM1 expression sufficiently controls the response of NPC cells to irradiation (IR). Mechanistically, cells exposed to IR, increased intracellular INSM1 competitively disrupts the interaction of cyclin D1 and CDK4 resulting in cell survival by the cyclin D1-dependent DNA repair machinery. Moreover, knockdown of INSM1 sensitives NPC cells to IR in vivo and protects xenograft mice from mortality. Taken together, these results indicate that INSM1 modulates NPC to radiotherapy by controlling cyclin D1-dependent DNA repair machinery that could be manipulated as a novel molecular target for NPC therapy.