The Role Of PLD3 In The Proliferation Of The Breast Cancer

Background: Phospholipase D3(PLD3),is a lesser known family member of the PLD superfamily,localized to the endoplasmic reticulum,highly expressed in the brain,especially mainly in neurons.Recent studies suggested that PLD3 over expression may associated with the phosphorylation of Akt.Thus we speculated that PLD3 may be associated with the development and progression of cancer cells.At present,there is few reports about the biological functions of PLD3 protein and the role of PLD3 in solid tumor still has not been defined.Our previous studies from the online prediction website(Gene expression-based outcome for breast cancer Online,GOBO)analyzed the PLD3 expression and prognosis in breast cancer patients.The results shows that patients with low expression of PLD3 reduced disease-free survial than patients with high expression,suggesting that PLD3 protein may be associated with recurrence and metastasis or prognosis for breast cancer patients.This study aims to clarify the role of PLD3 in the proliferation of breast cancer cells and to further explore the mechanism.Method: First,we studied the role of PLD3 in the proliferation of breast cancer cells in vitro,using lentivirus to build PLD3 high-expressing tumor cell lines.We use the si RNA to knock down the PLD3 expression.To determine the effect of PLD3 on the proliferation of breast cancer cells,MTT,plate colony and EDU were profermed.In addition,we performed a xenograft tumor assay by injecting T47D-PLD3 cells and T47D-Control cells into the mammary fat pads of female athymic nude mice to studied the role of PLD3 in vivo.At last,we used flow cytometry to access the role of PLD3 in the cell cycle progerssion and apoptosis.We use western blot method to study the cell cycle checkpoint protein expression changes.Results: Our results shows that in T47 D and MDA-MB-231 breast cancer cell lines,after over expression of PLD3,cell proliferation was significantly inhibited,and after depletion of PLD3 expression in MCF-7 cells,cell proliferation increased significantly,indicating that over expression of PLD3 inhibits cell proliferation.The xenograft tumor assay verified that over expression of PLD3 inhibit the breast cancer cells proliferation in vivo.In MDA-MB-231 and T47 D breast cancer cell lines,over expression of PLD3 lead to G2/M arrest,along with an increased number of multinucleated cells.Conclusion: PLD3 is related to the proliferation of breast cancer cells and the mechanism maybe associated with the arrest of cell cycle.