Project description:The tumor suppressor gene TP53 is the most frequently mutated gene in numerous cancer types, including prostate cancer (PCa). Specifically, missense mutations in TP53 are selectively enriched in PCa, and cluster to particular "hot spots" in the p53 DNA binding domain with mutation at the R273 residue occurring most frequently. While this residue is similarly mutated to R273C-p53 or R273H-p53 in all cancer types examined, in PCa selective enrichment of R273C-p53 is observed. Importantly, examination of clinical datasets indicated that TP53 heterozygosity can either be maintained or loss of heterozygosity (LOH) occurs. Thus, to mimic tumor-associated mutant p53, R273C-p53 and R273H-p53 isogenic PCa models were developed in the presence or absence of wild-type p53. In the absence of wild-type p53, both R273C-p53 and R273H-p53 exhibited similar loss of DNA binding, transcriptional profiles, and loss of canonical tumor suppressor functions associated with wild-type p53. In the presence of wild-type p53 expression, both R273C-p53 and R273H-p53 supported canonical p53 target gene expression yet elicited distinct cistromic and transcriptional profiles when compared to each other. Moreover, heterozygous modeling of R273C-p53 or R273H-p53 expression resulted in distinct phenotypic outcomes in vitro and in vivo. Thus, mutant p53 acts in a context-dependent manner to elicit pro-tumorigenic transcriptional profiles, providing critical insight into mutant p53-mediated prostate cancer progression.
Project description:Transcription factor ZIC2 plays a pro-tumorigenic role in several human cancers. Herein, we demonstrate that elevated ZIC2 expression was associated with lower overall and post-progression survival of epithelial ovarian cancer (EOC) patients. Knockout of ZIC2 in EOC cells attenuated tumorigenic phenotypes in vitro and in vivo, indicating a pro-tumorigenic role for ZIC2 in EOC. On the other hand, however, overexpression of ZIC2 in EOC cells that do not express endogenous ZIC2 promoted cell migration and sphere formation, but inhibited cell growth and colony formation in vitro and tumor growth in vivo, indicating a context-dependent function for ZIC2 in EOC. Transcriptomic study showed that ZIC2-regulated genes were involved in multiple biological processes and signaling pathways associated with tumor progression and that ZIC2 regulated common or distinct genes in ZIC2 knockout and overexpression models, which explains the consistency and discrepancy in ZIC2 functions observed in the two models. In conclusion, our findings reveal a context-dependent role for ZIC2 in regulating tumorigenic phenotypes in EOC, providing evidence that ZIC2 can be a potential therapeutic target for EOCs that express a high level of ZIC2.
Project description:Background and aims: Tertiary lymphoid structures (TLSs) are formed in many cancer types and have been correlated with better prognosis and response to immunotherapy. In liver cancer, TLSs have been reported to be pro-tumorigenic as they harbor tumor progenitor cells and nurture their growth. The processes involved in TLS development and the acquisition of a pro- or anti-tumorigenic phenotype in cancer are largely unknown. RORc expressing immune cells have been previously implicated in TLS formation, however, their role in TLS development in the context of inflammation-associated liver cancer remains unexplored. Methods: IKKβ(EE)Hep mice, exhibiting chronic liver inflammation and TLS formation followed by liver cancer, were crossed with RORc knockout mice to explore the effect of RORc on TLS and tumor formation. Transcriptional, proteomic and immunohistochemical techniques were used to analyze TLS phenotypes. CD4, CD8 and B cell depletions were used to analyze their contribution to liver TLS and tumor formation. Results: RORc expressing cells were detected within TLSs of both human patients and mice which develop intrahepatic cholangiocarcinoma. In mice, RORc expressing cells negatively regulate TLS formation, since in their absence TLSs form in excess. CD4 cells are essential for liver TLS formation whereas B cells are required for TLS formation specifically in the absence of RORc expressing cells. Importantly, in chronically inflamed livers lacking RORc expressing cells, TLSs become anti-tumorigenic, resulting in reduced tumor load. Comparing liver pro- and anti-tumorigenic TLSs, revealed enrichment of exhausted CD8 cells that retained effector functions, as well as germinal center B cells and plasma cells in anti-tumorigenic TLSs. Cell depletion experiments revealed a role mainly for B cells in limiting tumor development, possibly via tumor-directed antibodies. Conclusions: RORc expressing cells negatively regulate B cell responses, and facilitate the pro-tumorigenic functions of hepatic TLSs.