American Association for Cancer Research
15417786mcr200587-sup-246528_1_supp_6413321_qd6nks.docx (15.57 MB)

Supplementary Figures 1-15 from Merkel Cell Polyomavirus Small T Antigen Activates Noncanonical NF-κB Signaling to Promote Tumorigenesis

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journal contribution
posted on 2023-04-03, 19:45 authored by Jiawei Zhao, Yuemeng Jia, Shunli Shen, Jiwoong Kim, Xun Wang, Eunice Lee, Isaac Brownell, Jeong Hee Cho-Vega, Cheryl Lewis, Jade Homsi, Rohit R. Sharma, Richard C. Wang

Figure S1. Protein sequence alignment of HPyV6, HPyV7 and MCPyV small T antigens. Figure S2. Expression of HPyV sT induces p53-dependent senescence in human fibroblasts. Figure S3. Proliferation of BJ fibroblasts with expression of HPyV sT. Figure S4. Analysis of RNA-Seq from HPyV6, HPyV7, and MCPyV sT expressing BJ fibroblasts. Figure S5. Time course and extended analysis of additional SASP gene expression in BJ cells after sT expression. Figure S6. MCPyV sT shRNA confirms role of sT in SASP gene expression. Figure S7. Impact of LSD motif of MCPyV sT on gene expression and proliferation. Figure S8. MCPyV st, but not HPyV6/7 sT, stabilizes and activates c-Myc in an LSD motif dependent manner. Figure S9. Chromatin remodeling signatures induced by MCPyV sT. Figure S10. Mechanism of ncNF-κB and SASP induction by MCPyV sT. Figure S11. ncNF-κB signaling is required for SASP and EZH2 expression and affects cell proliferation. Figure S12. PyV sT conditioned media is not sufficient for growth in low serum. Figure S13. ST expression in VP-MCC lines and tumors. Figure S14. Impact of ncNF-κB inhibition on VP-MCC and VN-MCC. Figure S15. Summary Figure.






Multiple human polyomaviruses (HPyV) can infect the skin, but only Merkel cell polyomavirus (MCPyV) has been implicated in the development of a cancer, Merkel cell carcinoma (MCC). While expression of HPyV6, HPyV7, and MCPyV small T antigens (sT), all induced a senescence-associated secretory phenotype (SASP), MCPyV sT uniquely activated noncanonical NF-κB (ncNF-κB), instead of canonical NF-κB signaling, to evade p53-mediated cellular senescence. Through its large T stabilization domain, MCPyV sT activated ncNF-κB signaling both by inducing H3K4 trimethylation-mediated increases of NFKB2 and RELB transcription and also by promoting NFKB2 stabilization and activation through FBXW7 inhibition. Noncanonical NF-κB signaling was required for SASP cytokine secretion, which promoted the proliferation of MCPyV sT–expressing cells through autocrine signaling. Virus-positive MCC cell lines and tumors showed ncNF-κB pathway activation and SASP gene expression, and the inhibition of ncNF-κB signaling prevented VP-MCC cell growth in vitro and in xenografts. We identify MCPyV sT–induced ncNF-κB signaling as an essential tumorigenic pathway in MCC. This work is the first to identify the activation of ncNF-κB signaling by any polyomavirus and its critical role in MCC tumorigenesis.

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