Expression Of RSK4 And Its Correlation With Expression Of PCNA, Ki67, MMP-2 And MMP-9 In Breast Cancer

Background: In recent years, the X chromosome linked genes have been reported in cancer. Ribosomal S6 kinase 4 (p90 ribosomal protein S6 kinase 4, RSK4) gene is one of the X chromosome linked genes which maps to chromosme Xq21. RSK4 which is a group of ser/Thr kinases can be activated by a variety of extracellular signal such as growth factors, peptide hormones and neurotransmitters. Because of their involvement in cell cycle regulation and control, It has gradually raised concern. There are some reserches about the relationship between RSK4 and breast cancer in foreign countries, but less for research of RSK4. Recent research has shown that, RSK4 breast cancer are probably a tumor suppressor gene.Objective: To investigete the expression of RSK4 in human breast cancer, explore the relationship between RSK4 expression and clinicopathological features, and relationship between the expression of RSK4 and the expressions of PCNA, Ki-67, MMP-2, MMP-9 in breast cancer.Method:1. The expression of RSK4 mRNA was detected by RT-PCR (reverse transcriptase polymerase chainreaction) in 56 cases of breast cancer , 56 cases of adjacent normal breast tissues and 20 cases of breast benign lesion tissues .2. The expression of RSK4, PCNA, Ki-67, MMP2 and MMP9 were detected by S-P immunohistochemistry in 56 cases of breast cancer, 56 cases of adjacent normal breast tissues and 20 cases of breast benign lesion. Results:1. The expression rate of RSK4mRNA in 56 cases of breast cancer and normal breast tissues were 48.21% and 76.67%, statistical difference was found between them (P<0.05); While the rate of RSK4 mRNA expression in 20 cases of breast benign lesion was 75%, statistical difference was found beteewn breast cancer group and breast breast benign lesion group. The expression of RSK4mRNA were associated with tumor size and clinical stage (P<0.05), but had no correlation with age, lymph node metastasis.2. The rate of RSK4 protein expression was significant lower in breast carcinoma tissues(39.29%,22/56) than adjacent normal breast tissues (71.43%,40/56),statistical difference was found between them (P<0.01). statistical difference was also found beteewn breast carcinoma group and benign lesion group (P<0.01).The expression of RSK4 protein were associated with tumor size and clinical stage, lymph node metastasis (P<0.05) but had no correlation with age, ER, PR and Her-2 (P>0.05).3. concordance rate of RSK4mRNA and RSK4 protein is 73.21%(41/56);There were 17 cases (77.27%) of RSK4mRNA positive expression in 22 cases of RSK4 protein positive expression,while there were 24 cases of RSK4mRNA negative expression in 34 cases (70.59%) of RSK4 positive negative expression. correlation was found between the expression of RSK4mRNA and RSK4 protein(χ2 =10.254,P<0.05).4. The expression of RSK4 protein shew significant negative correlation with the expression of Ki67 protein in breast cancer (r=-0.342, P<0.01).Conclusion:1. These results indicate that the deletion and down regulation of RSK4 may promote the oncogenic, invasive, and metastatic potential of breast cancer. RSK4 is an X-linked breast cancer suppressor gene.2. The expression of RSK4 protein are associated with tumor size and clinical stage, but had no correlation with age, lymph node metastasis. RSK4 may be involved in the progress and the transfer of breast cancer.3.Useing Immunohistochemistry and RT-PCR to detect expression of RSK4,There are concordance between them.4. The expression of RSK4 was negative correlation with the expression of Ki67, both involved in the process of breast cancer.