Probes for MYC

Telomerase consists of at least two essential elements, an RNA component hTR or TERC that contains the template for telomere DNA addition, and a catalytic reverse transcriptase (TERT). While expression of TERT has been considered the key rate limiting component for telomerase activity, increasing evidence suggests an important role for the regulation of TERC in telomere maintenance and perhaps other functions in human cancer. By using three orthogonal methods including RNAseq, RT-qPCR, and an analytically validated chromogenic RNA in situ hybridization assay, we report consistent overexpression of TERC in prostate cancer. This overexpression occurs at the precursor stage (e.g. high grade prostatic intraepithelial neoplasia or PIN), and persists throughout all stages of disease progression. Levels of TERC correlate with levels of MYC (a known driver of prostate cancer) in clinical samples and we also show the following: forced reductions of MYC result in decreased TERC levels in 8 cancer cell lines (prostate, lung, breast, and colorectal); forced overexpression of MYC in PCa cell lines, and in the mouse prostate, results in increased TERC levels; human TERC promoter activity is decreased after MYC silencing; and MYC occupies the TERC locus as assessed by chromatin immunoprecipitation (ChIP). Finally, we show that knockdown of TERC by siRNA results in reduced proliferation of prostate cancer cell lines. These studies indicate that TERC is consistently overexpressed in all stages of prostatic adenocarcinoma, and its expression is regulated by MYC. These findings nominate TERC as a novel prostate cancer biomarker and therapeutic target.

Obesity increases the risk of hepatocellular carcinoma (HCC), but precise identification and characterization of druggable oncogenic pathways that contribute to the progression of NAFLD to HCC, and hence to the increased incidence and aggressiveness of HCC in obese individuals is lacking. In this regard, we demonstrate that the Indian Hedgehog (Ihh) signaling pathway is upregulated in the fatty livers of mice consuming a high fat diet, and furthermore sustained in HCC tumors specifically within the context of a NAFLD microenvironment. Using a diet-induced mouse model of HCC wherein only obese mice develop HCC, targeted ablation of hepatocyte-secreted Ihh results in a decreased tumor burden and lower grade tumors. Ihh activation regulates the transdifferentiation of ciliated stellate cells and proliferation of Epcam+ ductal cells to promote fibrosis. Mechanistically, increased expression of hitherto uncharacterized effectors of Hh pathway, namely Myc and Tgf-β2 is critical to the observed physiology. This pro-tumorigenic response is driven by increased expression of Wnt5a to effect a poorly-differentiated and invasive tumor phenotype. Wnt5a secreted from activated stellate cells act on Ror2-expressing hepatocytes. We further demonstrate that Wnt5a expression is also elevated in poorly-differentiated HCC cells, suggesting that these ligands are also able to function in an autocrine positive feedback manner to sustain poorly-differentiated tumors. Taken together, our study provides a mechanistic understanding for how Ihh signaling promotes HCC tumorigenesis specifically in obese mice. We propose that therapeutic targeting of the Hh pathway offers benefit for patients with dietary / NAFLD-driven steatotic HCC.