OBJECTIVETo investigate the effects of the γ isoform of Ca(2+)/calmodulin-dependent protein kinase II (CaMKIIγ) on colorectal cancer (CRC) cell growth in vitro and in vivo and explore the mechanisms.

METHODSThe mRNA levels of CaMKIIγ in 5 CRC cell lines, tumor tissues and matched adjacent tissues from 20 CRC patients were examined by semi-quantitative RT-PCR. The lentiviral vector pLenti6.3-MCS-IRES2-eGFP was used to generate the lentivirus particle Lenti-CaMKIIγ for transfecting SW620 cells. The proliferation ability of the transfected SW620-CaMKIIγ cells was assessed by growth curve and colony formation assay. The expression of IKKα, IKKβ, IKKγ, p-IKKα/β, p-IκB andIκB of the transfected cells were determined by Western blotting, and the expression and localization of nuclear factor-κB (NF-κB) p65 were detected by immunofluorescence. In nude mouse models bearing the transfected SW620-CaMKIIγ cell xenograft, the tumor volume was measured twice a week.

RESULTSCaMKIIγ mRNA showed high expressions in the 5 colorectal cancer cell lines. Eighteen of the 20 tumor tissues showed higher expressions of CaMKIIγ than the adjacent non-tumor tissues. The proliferation of transfected SW620-CaMKIIγ cells was enhanced significantly. CaMKIIγ activated NF-κB signaling pathway and led to NF-κB p65 nuclear translocation. In the tumor-bearing mouse model, the volume of the tumors generated by the transfected SW620-CaMKIIγ cells was 1.46- and 1.68-fold higher than that of the tumors with the control cells at the 8th and 12th day, respectively.

CONCLUSIONCaMKIIγ can effectively promote the growth of colorectal cancer cells in vitro and in vivo by activating NF-κB signaling pathway.