Phospholipase D Induced Cell Proliferation And Invasion Via Wnt Signaling Pathway In Human Colon Cancer Cells

Colorectal cancers is one of the most common gastrointestinal malignancy, the incidence rate of colorectal cancers is the forth in malignant tumors over the world, which is a serious threat to human health. In recent years, the incidence of colorectal cancers continued to show a rising trend. Phospholipase D(PLD) has emerged as a regulator of several critical aspects of cell physiology. Two mammalian PLD genes have been reported:PLD1and PLD2. There are abnormalities in PLD expression and activity in many human cancers, a large number of studies showed that PLD has been implicated in progression of variety carcinoma. But the mechanism remains poorly understood. Aberrant activation of Wnt/β-catenin signaling, followed by hyper-activation of target genes, is linked to a wide range of cancers. New studies reveal PLD is a transcriptional target of β-catenin/T-cell factor (TCF) and reinforces Wnt/β-catenin signaling related with cellular transformation. However, the depth relationship between Wnt signaling and PLD remains incomplete. In this study, human colon carcinoma cell lines KM12C、KM12SM, PLD stable transfected cell lines and the model of human colon carcinoma xenograft in nude mice were studied to investigate the effect of phospholipase D on colon cancers and especially to find the effect of phospholipase D on Wnt-mediated proliferation pathway and migration pathway.First of all, we determined the viabilities of the cell lines tranfected with PLD plasmids for24h. The results show that PLD can significantly increase the viabilities of human colon carcinoma cell lines KM12C and KM12SM. We did the wound healing assays to investigate whether PLD can induce human colon carcinoma cells migration. We found that PLD induced KM12C and KM12SM cells migration after transfected PLD plasmids for48h. We also found that PLD significantly increased expression of β-catenin in nucleus in KM12C and KM12SM cells, and also increased expression of c-Myc and cyclinDl. Then we build the PLD stable transfected cell lines and use the MTT assay, realtime PCR, luciferase reporter gene assay and cell invasion assay to detect the biological function of PLD stable transfection cells. We found that in PLD stable transfected cells, the activity of Wnt singaling were higher than the control cells, the c-Myc and cyclinDl mRNA level and the cell invasion ability were also increased. Finally, we found that PLD increased the proliferation of KM12SM and the expression of genes related to cell proliferation and target genes of Wnt signaling in tumor tissues.Conclusions:our studies confirm that phospholipase D can increase cell viabilities, induce cell migration and invasion, and clarify that phospholipase D induced cell proliferation and tumor metastasis via overexpress β-catenin in nucleus and activate Wnt signaling pathway in KM12C and KM12SM cells. This study may provide the molecular basis for anticancer agents targeting phospholipase D.