The Mechanism Of CBX6 In Breast Cancer Proliferation

Objective: Deregulated cell cycle is the biological features of uncontrolled cell proliferation in malignant tumors.Chromobox (CBX) protein family members are canonical components in polycomb repressive complex 1 (PRC 1),playing an extremely important role in the epigenetic regulatory.Although several CBXs have been reported to involved in tumorigenesis and progression,the role and mechanism of CBX6 in cancer development and progression is still limited.Our current studies focused on the influence of CBX6 expression level in breast cancer cell proliferation,further explored the connection of CBX6 expression with breast cancer cell proliferation,and preliminarily studied the mechanisms of CBX6 in regulating the cell cycle pathway.Content: We determined the CBX6 expression in breast cancer cell lines and normal breast epithelium cells;Then we studied the effect of CBX6 expression on breast cancer cell proliferation;And detected the influence of CBX6 expression level on breast cancer cell cycle distribution and apoptosis by flow cytometry;Furthermore,we preliminarily studied the mechanisms of CBX6 in regulating breast cancer cell cycle pathway.Method: Our study firstly analysed CBX6 expression in breast cancer cell lines and normal breast epithelial cell lines by Western Blot;Using the PCR technique to amplify the target gene CBX6,and by connecting with the eukaryotic expression vector to construct CBX6 over-expression vector;We studied the effect of CBX6 expression on breast cancer cell proliferation by colony formation assays,MTT,EdU and detected the influence of CBX6 on breast cancer cell cycle distribution and apoptosis by flow cytometry.To investigate the relationship between CBX6 gene and cell cycle-related genes by using the cell cycle-related genes detection assay kit.Through the luciferase report system and RT-qPCR methods,we respectively researched the effect of CBX6 expression on the activity of miR-125a promoter and studied the influence of CBX6 expression on miR-125a-3p/5p expression.Through bioinformatics analysis and RT-qPCR methods,we study the relationship between miR-125a-3p with long chain non-coding RNA ANRIL.Our study firstly discussed the role and mechanisms of CBX6 in breast cancer proliferation,prospecting for effective molecular markers and targets to improve the early diagnosis and treatment methods.Results: We found that CBX6 is highly expressed in breast cancer cell lines,and at lower levels in normal breast epithelial cell lines;Depletion of CBX6 inhibited breast cancer cell proliferation and induced cell apoptosis accompanied with cell cycle arrest at G1 phase and up-regulation of the tumor suppressor p15 and p16 expression.Furthermore,we found that the miR-125a-3p expression was up-regulated in CBX6-depleted cells and overexpression of miR-125a-3p down-regulated the long non-coding RNA ANRIL expression.Conclusion: CBX6 was highly expressed in breast cancer,resulting in recruitment of PRC1 in the mir-125a promoter,and suppressed the miR-125a-3p expression.miR-125a-3p binds to and degrades the ANRIL expression.Overexpression of ANRIL caused by inhibition of miR-125a-3p expression suppressed the p15 and p16 expression,resulting in the induction of breast cancer cell proliferation.