| Background:Lung cancer now has already became the most important malignancy with highest mortality rate in the world. In recent decades, the mortality rate and the incidence of lung cancer stay high in China, and China will have the highest number of lung cancer patients in the world until 2025. predicted by World Health Organization (WHO). If patients with stage I lung cancer could be accepted surgery immediately, the survival rate will be raised up to 92%, otherwise, they will die within 5 years. However, the total 5-year survival rate of stage I to IV is only about 15%. Therefore, early diagnosis and treatment can effectively increase the survival of lung cancer patients. MicroRNAs (miRNAs) are a kind of small RNA with various biological functions, that have becoming research focus and been investigated by scientists because of their important roles in the growth, development, and physiological processes of organisms, especially in the initiation and progression of malignancies. miRNAs regulate many signaling pathways of several human malignant tumors, by either acting as cancer genes involved in tumor occurrence and development, or inhibiting the initiation and progression of tumors as antioncogenes. It has been reported that over 1/3 of human genes are regulated by miRNAs by precise gene -targeting, involved in cell proliferation, differentiation, apoptosis, and a series of physiological processes, and also in many human malignancies such as gastric cancer, breast cancer, lung cancer, etc. To sharpen the understanding of molecular biological and pathological mechanism on the occurrence and development of lung cancer, and lay the basis of improving the approaches for diagnosis and treatment, here we review the correlation between miRNA and lung cancer.and test how miR-34a affect the proliferation and apoptosis in lung carcinoma cells by down-regulation of SIRT1.Objective:To develop new approach for the treatment of human non-small cell lung cancer (HNSCLC) and establish new clinic treatment plan, this study investigated the expression of miR-34a and SIRT1 in HNSCLC tissures, and the function of miR-34a about inhibiting cell proliferation, promoting apoptosis and cell cycle control on HNSCLC cells.Method:(1) Cancer tissue samples were collected from 50 lung cancer patients, and non-cancerous tissue samples (around the tumor area) were also collected from 10 of them. Realtime PCR for miR-34a and SIRT1 gene expression were performed. Western blot was also applied to determine the protein expression level of SIRT1. Correlation between the expression of miR-34a and SIRT1 and the clinicopathological parameter from HNSCLC patients was also analysed.(2) To increase the expression amount of miR-34a, miR-34a mimic, a miR-34a simulant, was transfected into HNSCLC cell line H1299. Realtime PCR for miR-34a gene expression post transfection in H1299 cells was performed. MTT assay was applied to determine the cell proliferation effects. Annexin V-FITC/PI double-staining was used to test the effects on cell apoptosis. Flow cytometry was used to measure the impacts on cell cycles. Cell invasive ability of miR-34a was tested by Transwell chamber method, while the effects of cell migration rate was measured by wound healing assay.(3) HI299 cells were divided into 2 groups:① This group was further grouped into 2 subgroups that were respectively transfected with equal concentration of miR-mimics-mock (negative control), or miR-34a mimic (treatment group).② This group was also grouped into a negative and a postive subgroup (transfected without and with miR-34a inhibitor. Realtime PCR was performed to analyse miR-34a gene expression of each subgroups. Cell proliferation and protein expressions of SIRT1 protein were measured by BrdU assay and western blot assay, respectively.Results:(1) The miR-34a expression from cancerous tissue was significantly lower than tissue from non-cancerous area, while SIRT1 mRNA and protein expression showed contrary results. The expression of miR-34a from HNSCLC patients was related to the metastasis of lymph nodes, but independent of the age, gender, p-TNM staging, pathological type, or histopathologic grade.The expression of SIRT1 from HNSCLC patients was related to the metastasis of lymph nodes,p-TNM staging, and histopathologic grade, but independent of the age, gender, and pathological type.(2) MiR-34a was shown to inhibit the cell proliferation and promote apoptosis of H1299 cells, and affect the cell growth by blocking the cell cylcle at G1 phase. miR-34a could also inhibit the invasive and migarating abilities.(3) Cellular proliferative activity of H1299 cells was shown to be declined post miR-34a mimic transfection, however, this activity was increased then after adding miR-34a inhibitor. The protein expression of SIRT1 in H1299 cells showed decreased post transfection of miR-34a mimic, but significantly increased after adding miR-34a inhibitor.Conclusion:MiR-34a can inhibit the cell proliferation and promote cell apoptosis on HNSCLC cells by suppressing the expression of SIRT1, hintting that miR-34a has the protential to be an anti-oncogene by involving into the initiation and progression of HNSCLC, which may be also a novel tumor marker for clinical diagnosis, prognosis and targeted therapy of HNSCLC. |
PDF Full Text Request