PIPKIγ Regulates CCL2 Expression in Colorectal Cancer by Activating AKT-STAT3 Signaling

Figure 4

AKT activation by PIPKIγ mediated STAT3 phosphorylation and CCL2 expression in CRC. (a) q-PCR analysis of CCL2 mRNA levels in HCT116 and SW620 cells overexpressing PIPKIγ or not and treated with the AKT inhibitor ADZ5363 or the mTOR inhibitor rapamycin. (b) ELISA analysis of CCL2 protein levels in HCT116 and SW480 cells overexpressing PIPKIγ or not and treated with the AKT inhibitor ADZ5363 or the mTOR inhibitor rapamycin in FBS-free medium. (c) Western blot analysis of the phosphorylation levels of AKT, mTOR, and STAT3 in SW480 and LOVO cells treated with the AKT inhibitor ADZ5363 or the mTOR inhibitor rapamycin. Densitometric analysis presented in the right plane. Experiments were repeated twice; representative results are presented. (d) PIP2 level in the control, shPIPKIγ1, and shPIPKIγ2 cells was examined by a protein-lipid overlay assay. (e) ELISA analysis of CCL2 protein levels in PIPKIγ-depleted SW480 and LOVO cells transfected with continuously activated AKT or STAT3 plasmid. (f) Immunohistochemical analysis of PIPKIγ and p-STAT3 expression in a human Renji CRC tissue microarray. Representative low, median, and high PIPKIγ expression images are shown in the upper panel, and the corresponding samples’ p-STAT3 expression levels are shown in the lower panel. (g) Proposed mechanism of PIPKIγ-AKT-mTOR-STAT3-driven CCL2 expression in colorectal cancer cells.

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