Kaposi's Sarcoma-Associated Herpesvirus Infection Promotes Proliferation of SH-SY5Y Cells by the Notch Signaling Pathway

Abstract Background: The cancer caused by Kaposi's sarcoma-associated herpesvirus (KSHV) is one of the major causes of death in AIDS. Some patients have neurological symptoms and may be linked with KSHV infection, based on the herpesvirus has shown a neurotropic tendency in recent years. The objective of this study is to detect the effects of KSHV infection on neuronal SH-SY5Y cells and analyze differentially expressed genes. Methods: KSHV was collected from islk.219 cells. TaqMan real-time PCR was used to quantify KSHV copy numbers. KSHV was used to infect SH-SY5Y cells. Infection was confirmed by detection of GFP and viral gene expression. The KSHV copy number in supernatants and mRNA of latency-associated nuclear antigen (LANA), ORF26, K8.1A, replication and transcriptional activator (RTA) of infected SH-SY5Y cells was detected by real-time PCR. The proteins were detected by immunohistochemistry. Effects of KSHV on cell proliferation were detected by MTT and Ki-67 staining. Migration was detected by Transwell assays. The cell cycle was detected by flow cytometry. The expression of CDK4, CDK6, cyclin D1 and p27 were detected by western blots. Cell cycle proteins were detected again in LANA-overexpressing SH-SY5Y cells. Transcriptome sequencing was used to screen differentially expressed genes from KSHV-infected and uninfected SH-SY5Y cells. Components of the Notch signaling pathway were detected by western blots.Results: SH-SY5Y cells were successfully infected by KSHV and maintained the ability to produce virions. LANA, ORF26, K8.1A and RTA were expressed in KSHV-infected SH-SY5Y cells. After infection, cell proliferation was increased, but migration ability was downregulated and KSHV infection promoted the G0/G1 phase (P<0.05). CDK4, CDK6 and cyclin D1 were upregulated, and P27 was downregulated. After over-expression of LANA, expression of cyclin D1 and CDK4 increased. Transcriptome sequencing showed that 11,258 genes were upregulated and 1,967 were downregulated in KSHV-infected SH-SY5Y cells. The Notch signaling pathway was related to KSHV-infected SH-SY5Y cells, and western blots confirmed expression of Notch1, NICD, RBP-JK and Hes1 increased in KSHV-infected cells.Conclusion: KSHV can infect SH-SY5Y cells and promote proliferation. KSHV infection upregulated expression of Notch signaling pathway proteins, which may relate to improved cell proliferation.