LncRNA DLGAP1-AS2 promotes the radioresistance of rectal cancer stem cells by upregulating CD151 expression via E2F1.

BACKGROUND: Radiotherapy resistance is one of the major causes of rectal cancer treatment failure. LncRNA DLGAP1-AS2 participates in the progression of several cancers. We explored the role and potential mechanism of DLGAP1-AS2 in the radioresistance of rectal cancer stem cells. METHODS: HR8348-R cells, radioresistant cells from HR8348 after irradiation, were isolated into CD133 negative (CD133-) and positive (CD133+) cells. Cell proliferation, apoptosis, migration and tumorsphere formation were determined by CCK-8, flow cytometry, wound healing assay and tumorsphere formation assay, respectively. CD133, tumor stem cell drug resistance gene (MDR1 and BCRP1), DNA repair marker (γ-H2AX) and AKT/mTOR/cyclinD1 signaling were measured by Western blot. The relationship between DLGAP1-AS2 and E2F1 was verified using RIP. The interaction between E2F1 and CD151 promoter was confirmed using dual-luciferase reporter gene assay and ChIP. AKT inhibitor API-2 was employed for validating the effect of AKT/mTOR/cyclinD1 signaling in the radioresistance of rectal cancer cells. RESULTS: The DLGAP1-AS2 level was increased in CD133+ cells after irradiation. DLGAP1-AS2 knockdown inhibited the proliferation, migration and tumorsphere formation while stimulating apoptosis in CD133+ cells. DLGAP1-AS2 inhibition downregulated the expression of CD133, MDR1, BCRP1 and γ-H2AX and suppressed AKT/mTOR/cyclinD1 activation. DLGAP1-AS2 upregulated the expression of CD151 by interacting with E2F1. API-2 neutralized the promotive effects of overexpressed CD151 on radioresistance. CONCLUSION: DLGAP1-AS2 accelerates the radioresistance of rectal cancer cells through interactions with E2F1 to upregulate CD151 expression via the activation of the AKT/mTOR/cyclinD1 pathway.

Increased miR-323a induces bladder cancer cell apoptosis by suppressing c-Met.

The current study aimed to evaluate the expression and role of miR-323a in the progression of bladder cancer (BC), thereby providing a theoretical basis and potential therapy methods for BC patients. Our data showed that miR-323a levels were significantly reduced in BC tissues compared with those of non-cancerous tissues. Meanwhile, miR-323a was significantly decreased in human BC cell lines (T24, J82, TCCSUP, RT-112) than that in human normal bladder epithelial cell line SV-HUC-1. Furthermore, inhibition of miR-323a markedly enhanced the migration and invasive capacity of T24 and TCCSUP cells. Moreover, overexpression of miR-323a significantly prompted the apoptosis of BC cells. Dual luciferase reporter assay and western blot analysis confirmed that c-Met was a target gene of miR-323a. More importantly, upregulation of c-Met significantly prompted BC cell proliferation mainly as a result of the enhanced level of phosphorylation of AKT. This effect could be abolished when c-Met was silenced in BC cells. In summary, reduced miR-323a expression in BC contributed to enhanced BC cell proliferation and migration mainly by targeting c-Met.