Predicting The Distal Metastasis And Chemoresistance Using Plasma MiRNAs

Part one Predicting the distal metastasis and chemoresistance using plasma miRNAsObjective:In the clinic, prediction of metastasis and chemoresistance is a significant priority, but has not been well established. This study is to investigate whether dynamically monitoring serum miRNAs could predict the metastasis, chemoresistance, and prognosis.Methods:Serum miR-155, miR-200c, and miR-210level in15patients with colon cancer was measured by real-time PCR at different time points post-surgery and chemotherapy for3years.Results:Significant increases in miR-155, miR-200c, and miR-210level was observed in the serum and tumor tissues of colon cancer patients compared to that in healthy subjects. After surgery and chemotherapy, the serum levels of these miRNAs in patients with good prognosis were normalized to the level in healthy controls during3-year follow-up. In patients with recurrence and distal metastasis, serum miR-155, miR-200c, and miR-210levels remained at a higher level or were re-elevated after short period dropping off. In patients with good response to chemotherapy for metastatic tumors, re-elevation of miR-155was not significant compared to miR-200c and miR-210. In contrast, miR-155re-elevated more significant in patient without sensitization to chemotherapy than miR-200c and miR-210.Conclusion:our study suggests that re-elevation or keeping high serum miR-155level after surgery and chemotherapy is a sign for chemoresistance in colon cancer, while high and/or re-elevated miR-155, miR-200c, and miR-210levels implicates local recurrence and distal metastasis as well as poor prognosis. Part two The roles of miR-200c in colon cancer and associated molecular mechanismsBackground:The expression of miR-200c has been widely reported to be elevated in tumor tissues and serum of patients with colorectal cancer and has been found to correlate with poor prognosis. However, how miR-200c regulates the apoptosis, survival, invasion, metastasis of colon cancer cells, and tumor growth remains to be elucidated. This study seeks to investigate the role of miR-200c in colon cancer development and associated mechanisms.Methods:The expression of miR-200c in tumor and peritumoral tissues of101colon cancer patients was measured by real-time PCR. miR-200c expression in colon cancer HCT-116and HT-29cells was silenced by adenovirus-carried expression of antisense mRNA against miR-200c. The protein levels of PTEN, p53Ser15, PP1, and activated caspase-3in HCT-116and HT-29cells were measured by Western blot.Results:The expression of miR-200c was significantly higher in tumor tissues than that in peritumoral tissues of colon cancer patients. The elevated miR-200c expression significantly correlated with the TNM stage, lymph node metastasis, and invasion of colon cancer. Silencing miR-200c expression significantly induced cell apoptosis, inhibited long-term survival, invasion, and metastasis, and delayed xenograft tumor growth in HCT-116and HT-29cancer cells. Importantly, silencing miR-200c expression sensitized the therapeutic effect of Ara-C.The effects of silencing miR-200c expression were associated with upregulation of PTEN protein and p53Ser15phosphorylation levels in HCT-116and PTEN protein expression in HT-29cells.Conclusion:miR-200c functions as an oncogene in colon cancer cells through regulating tumor cell apoptosis, survival, invasion, and metastasis as well as xenograft tumor growth through inhibition of PTEN expression and p53phosphorylation.