ABSTRACT
Objective To investigate the relationship between miR-411 and breast cancer,and the expression of miR-411 and its effects and mechanism research on proliferation and metastasis in breast cancer.Methods Real-time polymerase chain reaction (RT-PCR) was used to detect the expression of miR411 in breast cancer cells and tissues.Methyl thiazolyl tetrazolium (MTT),clone formation assay and Transwell assay were used to detect the effect of miR-411 expression on the proliferation,migration and invasion in breast cancer cells.The effect of miR-411 on growth factor receptor-bound protein 2 (GRB2) expression in breast cancer cells was detected by RT-PCR and Western blot.The direct effect of miR-411 target on GRB2 was detected by dual luciferase reporter assay.MTT,clone formation assay and Transwell assay detect the effect of GRB2 expression on the proliferation and invasion in breast cancer cells.Detection the effect high expression of miR-411 on GRB2 downstream signaling pathway related molecules expression in breast cancer cell with Western blot.Results The expression of miR-411 in breast cancer tissues was significantly lower than that in adjacent non-cancerous tissues (P ＜ 0.05).The expression of miR-411 in breast cancer cells SK-BR-3,BT-549 and MDA-MB-231 was significantly lower (P ＜ 0.05).Compared to the negative control group,the transfection of miR-411 mimic inhibited the proliferation,migration and invasion of MDA-MB-231 breast cancer cells (P ＜ 0.05).Targetscan showed that miR-411 could bind to GRB2 3'UTR at position 741-747.Compared with the negative control group,GRB2 3'UTR wild-type plasmid and miR-411 co-transfection reduced the fluorescence activity (P ＜ 0.05).Transfection of siGRB2 significantly reduced the expression of GRB2 protein in MDA-MB-231 breast cancer cells (P ＜ 0.05).Compared to the negative control group,the inhibition of GRB2 expression reduced the proliferation and the number of colony formation of MDA-MB-231 breast cancer cells (P ＜ 0.05).Transwell assay showed that transfection of siGRB2 significantly reduced the number of invasive cells in MDA-MB-231 breast cancer cells (P ＜ 0.05).Conclusions miR-411 is related closely to the occurrence and development of breast cancer,miR-411-GRB2-Ras axis is expected to become a new target for biological treatment of breast cancer.
ABSTRACT
Objective To investigate the expression of neurotrophins receptor 75NTR in human breast cancer resistant cell line and its correlation with multidrug resistance. Methods Western blot was used to detect the expression level of p75NTR protein in various breast cancer cell lines and multidrug resistant cell lines. The over-expression vector and siRNA vector of p75NTR were constructed by gene recombination method. Western blot was used to detect the expression levels of p75NTR protein in transfected p75NTR and p75NTR - siRNA breast cancer resistant cell line MDA-MB-231/ADR;the sensitivity of MDA-MB-231 and MDA-MB-231/ADR to different chemotherapeutic anticancer drug (PTX ,ADM ,GEM ,DDP ,OXA) and the multi-drug resistance effects in over-expression and knock-down p75NTR MDA-MB-231/ADR were detected by CCK-8 assay. Results Western blot result showed that the expressions of p75NTR protein in the multidrug-resistant breast cancer cell lines MDA-MB-231/ADR and MCF-7/5-FU were higher than that of other breast cancer cell lines. Over-expression of p75NTRcan up-regulate the expression of p75NTR protein in MDA-MB-231/ADR;the CCK-8 assay indicated that over-expression of p75NTR can effectively enhance the resistance of MDA-MB-231/ADR cells to ADM,GEM and OXA. Conclusion The expression of p75NTR in breast cancer resistant cell line is higher than that of its parental cell line;over-expression of p75NTR can reduce the sensitivity to chemotherapeutic drugs and promote its multidrug resistance.
ABSTRACT
Objective To explore the expression of Topo Ⅱα and COX-2 in breast cancer tissues and investigate their correlations to clinicopathologic feature of breast cancer. MethodsThe expression of Topo Ⅱα and COX-2 in 50 specimens of breast cancer and their normal tissues were detected by immunohistochemistry. Their correlation to clinicopathologic features of breast cancer were analyzed.ResultsThe positive rates of Topo Ⅱα were 64 % (32/50) and 22 % (11/50) and COX-2 were 68 % (34/50) , 14 %(7/50) in breast cancer and normal tissue (P＜0.05). The expression of Topo Ⅱα was correlated to degree of differentiation (P ＜0.05), not correlated to patient age, tumor size, clinical stage and lymph node metastasis(P ＞0.05). The expression of COX-2 was correlated to tumor size, degree of differentiation, clinical stage and lymph node metastasis (P ＜0.05), not correlated to patient age (P ＞0.05). Conclusion Topo Ⅱα and COX-2 expression can be used as an indicator for predicting the differentiation, infiltration and metastasis characteristics of breast cancer.