[Spleen tyrosine kinase inhibits proliferation and promotes apoptosis of colorectal cancer cells in vitro via regulating Fra-1].

OBJECTIVE: To investigate the effects of spleen tyrosine kinase (SYK) overexpression on proliferation and apoptosis of colorectal cancer cells and explore the possible mechanism. METHODS: The mRNA expressions of SYK and Fra?1 in 10 clinical specimens of colorectal cancer and 10 adjacent tissues were measured with qRT?PCR, and their protein expressions were detected with Western blotting. The recombinant plasmid pcDNA.3.1?SYK was constructed and transfected into colorectal cancer cells to induce SYK overexpression, and the cell viability and proliferation were assessed using by MTT assay and BrdU assay, respectively; caspase?3 activity in the cells was evaluated with a commercial kit and the cell apoptosis was analyzed with Annexin?V FITC/PI assay. RESULTS: The expressions of SYK were significantly decreased in colorectal cancer tissues and colorectal cancer cell lines. Transfection of pcDNA.3.1?SYK into the colorectal cancer cells induced obviously upregulated mRNA and protein expressions of SYK, which caused a significant suppression of the cell viability and proliferation and enhancement of the cell apoptosis along with a significant inhibition of Fra?1 expression. CONCLUSION: s SYK overexpression inhibits the proliferation and promotes apoptosis of colorectal cancer cells, and these effects are possibly mediated by the regulation of Fra?1 expression by SYK.

MicroRNA­144 inhibits migration and proliferation in rectal cancer by downregulating ROCK­1.

Cancer of the colon and rectum are two distinct entities, which require different treatment strategies and separate treatment. MicroRNAs (miRNAs) act as critical regulators of genes involved in several biological processes. Aberrant alterations of miRNAs have been found in several types of cancer, including colon cancer and rectal cancer. Extensive catalogues of downregulated miRNAs have been identified for colon cancer, whereas only limited data are available for rectal cancer. An example of miRNA profiling in a previous study found that miRNA (miR)­144 showed aberrant expression and appeared to be rectal cancer­specific, its expression not being reported in colon cancer. In the present study, the role of miR­144 in rectal cancer was investigated. SW837 and SW1463 cell lines were selected as rectal cell carcinoma cells. Using reverse transcription-quantitative polymerase chain reaction, western blot, BrdU, cell migration and cell viability assays, it was found that the expression levels of miR­144 were significantly reduced in the SW837 and SW1463 cell lines, and the overexpression of miR­144 suppressed rectal cancer cell viability, migration and proliferation. In addition, Rho­associated coiled­coil containing protein kinase 1 (ROCK1) was identified as a target of miR­144 in the rectal cancer cells. The supplementation of ROCK1 markedly restored the cell migration and proliferation, which was inhibited by miR­144. Together, the data of the present study demonstrated that miR­144 acts as a tumor suppressor by targeting ROCK1, and indicates the potential of miR­144 as a novel biomarker and target in the treatment of rectal cancer.

Downregulation of rho-associated protein kinase 1 by miR-124 in colorectal cancer.

AIM: To investigate the roles and interactions of rho-associated protein kinase (ROCK)1 and miR-124 in human colorectal cancer (CRC). METHODS: Expression of ROCK1 protein was examined by Western blotting, and quantitative reverse transcriptase PCR was performed to measure expression of ROCK1 mRNA and miR-124. Two cancer cell lines were transfected with pre-miR-124 (mimic) and anti-miR-124 (inhibitor) and the effects on ROCK1 protein and mRNA expression were observed. In addition, cell proliferation was assessed via a 5-ethynyl-2' deoxyuridine assay. Soft agar formation assay, and cell migration and invasion assays were used to determine the effect of survivin on the transformation and invasion activity of CRC cells. RESULTS: miR-124 was significantly downregulated in CRC compared to normal specimens (0.603 ± 0.092 vs 1.147 ± 0.286, P = 0.016) and in metastatic compared to nonmetastatic CRC specimens (0.416 ± 0.047 vs 0.696 ± 0.089, P = 0.020). Expression of miR-124 was significantly associated with CRC metastasis, tumor T and N stages, and tumor grade (all P < 0.05). ROCK1 protein was significantly increased in CRC compared to normal tissues (1.896 ± 0.258 vs 0.866 ± 0.136, P = 0.026), whereas ROCK1 mRNA expression was unaltered (2.613 ± 0.251 vs 2.325 ± 0.246). miR-124 and ROCK1 were inversely expressed in CRC tissues and cell lines. ROCK1 mRNA was unaltered in cells transfected with miR-124 mimic and miR-124 inhibitor, compared to normal controls. There was a significant reduction in ROCK1 protein in cells transfected with miR-124 mimic and a significant increase in cells transfected with miR-124 inhibitor (Ps < 0.05). Transformation and invasion of cells transfected with miR-124 inhibitor were significantly increased compared to those in normal controls (P < 0.05). Cells transfected with miR-124 inhibitor showed increased cell proliferation. CONCLUSION: miR-124 promotes hyperplasia and contributes to invasion of CRC cells, but downregulates ROCK1. ROCK1 and miR-124 may play important roles in CRC.