Kaposi's sarcoma-associated herpesvirus infection promotes proliferation of SH-SY5Y cells by the Notch signaling pathway.

backgroundThe cancer caused by Kaposi's sarcoma-associated herpesvirus (KSHV) infection is one of the major causes of death in AIDS patients. Some patients have neurological symptoms, which appear to be associated with KSHV infection, based on the neurotropic tendency of this virus in recent years. The objectives of this study were to investigate the effects of KSHV infection on neuronal SH-SY5Y cells and to identify differentially expressed genes.

methodsKSHV was collected from islk.219 cells. Real-time PCR was used to quantify KSHV copy numbers. KSHV was used to infect SH-SY5Y cells. The KSHV copy number in the supernatants and mRNA levels of latency-associated nuclear antigen (LANA), ORF26, K8.1 A, and replication and transcriptional activator (RTA) were detected by real-time PCR. Proteins were detected by immunohistochemistry. The effect of KSHV infection on cell proliferation was detected by MTT and Ki-67 staining. Cell migration was evaluated by Transwell and wound healing assays. The cell cycle was analyzed by flow cytometry. The expression of CDK4, CDK5, CDK6, cyclin D1, and p27 were measured by western blotting. The levels of cell cycle proteins were re-examined in LANA-overexpressing SH-SY5Y cells. Transcriptome sequencing was used to identify differentially expressed genes in KSHV-infected cells. The levels of Notch signaling pathway proteins were measured by western blotting. RNA interference was used to silence Notch1 and proliferation were analyzed again.

resultsSH-SY5Y cells were successfully infected with KSHV, and they maintained the ability to produce virions. KSHV-infected SH-SY5Y expressed LANA, ORF26, K8.1 A, and RTA. After KSHV infection, cell proliferation was enhanced, but cell migration was suppressed. KSHV infection accelerated the G0/G1 phase. CDK4, CDK5, CDK6, and cyclin D1 expression was increased, whereas p27 expression was decreased. After LANA overexpression, CDK4, CDK6 and cyclin D1 expression was increased. Transcriptome sequencing showed that 11,258 genes were upregulated and 1,967 genes were downregulated in KSHV-infected SH-SY5Y. The Notch signaling pathway played a role in KSHV infection in SH-SY5Y, and western blots confirmed that Notch1, NICD, RBP-Jĸ and Hes1 expression was increased. After silencing of Notch1, the related proteins and cell proliferation ability were decreased.

conclusionsKSHV infected SH-SY5Y cells and promoted the cell proliferation. KSHV infection increased the expression of Notch signaling pathway proteins, which may have been associated with the enhanced cell proliferation.