Boufaied, N. | bioRxiv Science

bioRxiv2021

SOCS3-mediated activation of p53-p21-NRF2 axis and cellular adaptation to oxidative stress in SOCS1-deficient hepatocellular carcinoma

SOCS1 and SOCS3 genes, frequently repressed in hepatocellular carcinoma (HCC), function as tumor suppressors in hepatocytes. However, TCGA transcriptomic data revealed that SOCS1-low/SOCS3-high specimens displayed more aggressive HCC than SOCS1-low/SOCS3-low cases. We show that hepatocyte-specific Socs1-deficient livers upregulate Socs3 expression following genotoxic stress. Whereas deletion of Socs1 or Socs3 increased HCC susceptibility, ablation of both genes attenuated HCC growth. SOCS3 promotes p53 activation in SOCS1-deficient livers, leading to increased expression of CDKN1A (p21WAF1/CIP1), which coincides with elevated expression and transcriptional activity of NRF2. Deleting Cdkn1a in SOCS1-deficient livers diminished NRF2 activation, oxidative stress and HCC progression. Elevated CDKN1A expression and enrichment of antioxidant response genes also characterized SOCS1-low/SOCS3-high HCC. SOCS1 expression in HCC cell lines reduced oxidative stress, p21 expression and NRF2 activation. Our findings demonstrate that SOCS1 controls the oncogenic potential of SOCS3-driven p53-p21-NRF2 axis and suggest that NRF2-mediated antioxidant response represents a drug target in SOCS1-deficient HCC.

cancer biology↗

bioRxiv2021

MYC drives aggressive prostate cancer by disrupting transcriptional pause release at androgen receptor targets

c-MYC (MYC) is a major driver of prostate cancer tumorigenesis and progression. Although MYC is overexpressed in both early and metastatic disease and associated with poor survival, its impact on prostate transcriptional reprogramming remains elusive. We demonstrate that MYC overexpression significantly diminishes the androgen receptor (AR) transcriptional program (the set of genes directly targeted by the AR protein) in luminal prostate cells without altering AR expression. Importantly, analyses of clinical specimens revealed that concurrent low AR and high MYC transcriptional programs accelerate prostate cancer progression toward a metastatic, castration-resistant disease. Data integration of single-cell transcriptomics together with ChIP-seq revealed an increased RNA polymerase II (Pol II) promoter-proximal pausing at AR-dependent genes following MYC overexpression without an accompanying deactivation of AR-bound enhancers. Altogether, our findings suggest that MYC overexpression antagonizes the canonical AR transcriptional program and contributes to prostate tumor initiation and progression by disrupting transcriptional pause release at AR-regulated genes. STATEMENT OF SIGNIFICANCEAR and MYC are key to prostate cancer etiology but our current understanding of their interplay is scarce. Here we show that the oncogenic transcription factor MYC can pause the transcriptional program of the master transcription factor in prostate cancer, AR, while turning on its own, even more lethal program.

genomics↗