| Background:Breast cancer is the second most common cause of cancer death in women,and its morbidity and mortality is consecutively increasing.The incidence of breast cancer in China has increased more than twice the global growth rate in recent years as the country urbanized at a faster pace,making breast cancer the sixth leading cause of cancer-related deaths among Chinese women.Currently,a variety of treatments are available for the treatment of breast cancer,including conventional surgical resection,radiation therapy,chemotherapy,endocrine therapy,and molecular targeted therapy.Early detection and screening are still effective ways to improve the prognosis and survival of breast cancer patients.However,TNBC is characterized by high heterogeneity,poor differentiation,high proliferative capacity,a large overall tumor size and lacks of specific molecular targets.Large-scale genome sequencing of TNBC tumors did not reveal any potential mutations in the therapeutic target genes.Therefore,the exploration of the key molecular mechanisms in the occurrence and development of TNBC is an important direction of scientists.MicroRNAs,19-25 nucleotides,are a class of non-coding RNAs that are highly conserved during evolution.miRNA could regulate cell proliferation,apoptosis,differentiation and metabolism.involved in physiological processes through specifically binding to the complementary sequence of the 3' untranslated region of the target gene.Recent studies have shown that miRNAs are involved in the occurrence and development of various diseases including triple negative breast cancer.miR-187 is aberrantly expressed in various diseases,and it participates in the development and progression of tumors.Recent studies have shown that the bioinformatic analysis indicated that miR-187 is highly expressed in breast cancer,which can be used as a molecular marker for prognosis and therapeutic effect of breast cancer.miR-187 also might be involved in the growth and metastasis of breast cancer.However,whether mir-187 is abnormally expressed and plays a role in triple negative breast cancer still need further investigations.ARRDC3 is a member of the arrestin family,which play a key role in the mediation of G protein-coupled receptor signaling.Down-regulated ARRDC3 ablates the degradation of integrin family molecule ITG?4 and GPCR signaling protein PAR1,which promtes the growth and metastasis in triple negative breast cancer.However,the molecular mechanism of abnormal expression of ARRDC3 in triple negative breast cancer is still not fully understood.Through bioinformatics analysis,we found that ARRDC3 might be the target gene of miR-187.Based on these studies,we hypothesized that miR-187 is highly expressed in triple negative breast cancer,and miR-187 could promote the proliferation,migration and invasion of triple negative breast cancer cells by directly targeting ARRDC3.Objectives:1.To clarify the role of miR-187 in the proliferation,invasion and migration of triple negative breast cancer cells.2.To elucidate the specific molecular mechanisms underlying the role of miR-187 in regulating the proliferation,invasion and migration of triple negative breast cancer cells.Methods:1.Real-time PCR was used to detect the expression level of miR-187 in triple negative breast cancer cell lines and tissues.2.Triple negative breast cancer cell line with lower expression of miR-187 was transfected with miR-187 mimic,and triple negative breast cancer cell line with higher expression of miR-187 was transfected with miR-187 inhibitor,respectively.CCK-8 assay and colony formation assay were performed to investigate the role of miR-187 on the proliferation of triple negative breast cancer cells.3.Triple negative breast cancer cell line with lower expression of miR-187 was transfected with miR-187 mimic,and triple negative breast cancer cell line with higher expression of miR-187 was transfected with miR-187 inhibitor,respectively.Transwell invasion assay and migration assay were used to observe the effects of miR-187 on the invasion and migration of triple negative breast cancer cells.4.Bioinformatics analysis and dual-luciferase reporter assay were performed to validate whether ARRDC3 was a direct target of miR-187.Western Blot was performed to confirm the regulatory role of miR-187 on the protein level of ARRDC3.5.By simultaneously overexpressing miR-187 and ARRDC3,CCK-8 assay,colony formation,Transwell invasion and migration assay were performed to determine whether miR-187 regulates the proliferation,invasion and migration of triple negative breast cancer cells through ARRDC3.6.Western Blot was used to detect the expression of the potential target gene ARRDC3 in triple negative breast cancer tissues and cell lines.Results:1.Real-time PCR showed that the expression of miR-187 was significantly increased in triple negative breast cancer cell lines and tissues.2.Overexpression of miR-187 promoted the proliferation and colony formation of triple negative breast cancer cells,and inhibition of miR-187 inhibited the proliferation and colony formation of triple negative breast cancer cells.3.Overexpression of miR-187 could promote the invasion and migration of triple negative breast cancer cells,and inhibition of miR-187 could inhibit the invasion and migration of triple negative breast cancer cells.4.Bioinformatic analysis and dual-luciferase reporter assay confirmed that ARRDC3 is a direct target of miR-187.Western Blot assay showed that miR-187 could negatively regulate the protein level of ARRDC3 in triple negative breast cancer cells.5.miR-187 promoted the proliferation,invasion and migration of triple negative breast cancer cells by directly targeting ARRDC3.6.Western Blot assay showed that ARRDC3 was significantly down-regulated in triple negative breast cancer cell lines and tissues.Conclusion:In this study,we first found that miR-187 is highly expressed in triple negative breast cancer tissues and cell lines,and miR-187 could promote the proliferation,invasion and migration of triple negative breast cancer cells by directly targeting the tumor suppressor gene ARRDC3.The results further enriched the miRNAs involved in the pathogenesis of triple negative breast cancer,which provides a novol target for the treatment of triple negative breast cancer. |
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