OncoTargets and Therapy (Sep 2019)
PLK1 contributes to autophagy by regulating MYC stabilization in osteosarcoma cells
Abstract
Hao Mo,* Juliang He,* Zhenchao Yuan, Zhenjie Wu, Bin Liu, Xiang Lin, Jian Guan Department of Bone and Soft Tissue Surgery, Affiliated Tumor Hospital of Guangxi Medical University, Nanning, People’s Republic of China*These authors contributed equally to this workCorrespondence: Jian GuanDepartment of Bone and Soft Tissue Surgery, Affiliated Tumor Hospital of Guangxi Medical University, He Di Road, #71, Nanning 530021, People’s Republic of ChinaTel +86 0 771 577 9346Email [email protected]: PLK1, a typical PLK protein, is the main driver of cancer cell growth and proliferation. It is an inhibitor of the protein kinases that is currently being investigated in clinical studies. It is often used as a tumor marker, as high PLK1 expression correlates with poor prognosis in cancer. Overexpression of MYC is a hallmark of many human cancers. MYC modulates the transcription of thousands of genes that required to coordinate a series of cellular processes, including those essential for growth, proliferation, differentiation, self-renewal and apoptosis. To date, functions of PLK1 and MYC on tumor are mostly studied in separate researches, and studies on their mutual crosstalk are lacking.Purpose: To investigate the mechanism of PLK1 and MYC in regulating progress of osteosarcoma.Methods: Protein level was examined using Western blot. Animal experiments were performed with female FOX CHASE severe combined immunodeficient mice. Mice were randomly divided into experimental or control groups.Results: PLK1 or MYC promoted the proliferation of osteosarcoma cells through the autophagy pathway. PLK1 contributed to MYC protein stabilization. PLK1 inhibition enhanced MYC degradation in osteosarcoma cells. PLK1 inhibition led to a marked decline in MYC protein abundance. The representative MYC target genes were deregulated by PLK1 inhibitors. BI2536 treatment caused a significant delay in xenograft tumor growth in mice injected with U-2 OS cells subcutaneously, with lower mean tumor weight compared to the control group.Conclusion: PLK1 is crucial for MYC stabilization. It promotes cell proliferation by autophagy pathway in osteosarcoma cells. Data validate PLK1 as a potential therapeutic target in osteosarcoma caused by MYC-amplified.Keywords: autophagy, PLK1, MYC, stabilization, osteosarcoma cells
