Stevers, N. | bioRxiv Science

bioRxiv2021

Pan-cancer imaging of TERT expression using deuterium magnetic resonance spectroscopy-based assessment of pyruvate metabolism

Telomerase reverse transcriptase (TERT) expression is indispensable for tumor immortality. Non-invasive methods of imaging TERT can, therefore, report on tumor proliferation and response to therapy. Here, we show that TERT expression is associated with elevated levels of the redox metabolite NADH in multiple cancers, including glioblastoma, oligodendroglioma, melanoma, neuroblastoma, and hepatocellular carcinoma. Mechanistically, TERT acts via the metabolic regulator FOXO1 to upregulate nicotinamide phosphoribosyl transferase, which is the key enzyme for NADH biosynthesis. Importantly, deuterium magnetic resonance spectroscopy (2H-MRS), which is a novel, clinically translatable metabolic imaging modality, can be leveraged for imaging TERT-linked NADH in preclinical tumor models in vivo. Since NADH is essential for pyruvate flux to lactate, 2H-MRS following administration of 2H-labeled pyruvate non-invasively visualizes TERT expression and reports on early response to therapy. Collectively, our study provides insights into the mechanisms of TERT-linked metabolic reprogramming and, importantly, establishes 2H-MRS as a pan-cancer strategy for imaging tumor immortality.

cancer biology↗

bioRxiv2021

An mRNA processing pathway suppresses metastasis by governing translational control from the nucleus

Cancer cells often co-opt post-transcriptional regulatory mechanisms to achieve pathologic expression of gene networks that drive metastasis. Translational control is a major regulatory hub in oncogenesis, however its effects on cancer progression remain poorly understood. To address this, we used ribosome profiling to compare genome-wide translation efficiencies of poorly and highly metastatic breast cancer cells and patient-derived xenografts. We developed novel regression-based methods to analyze ribosome profiling and alternative polyadenylation data, and identified HNRNPC as a translational controller of a specific mRNA regulon. Mechanistically, HNRNPC, in concert with PABPC4, binds near to poly(A) signals, thereby governing the alternative polyadenylation of a set of mRNAs. We found that HNRNPC and PABPC4 are downregulated in highly metastatic cells, which causes HNRNPC-bound mRNAs to undergo 3 UTR lengthening and subsequently, translational repression. We showed that modulating HNRNPC expression impacts the metastatic capacity of breast cancer cells in xenograft mouse models. We also found that a small molecule, previously shown to induce a distal-to-proximal poly(A) site switching, counteracts the HNRNPC-PABPC4 driven deregulation of alternative polyadenylation and decreases the metastatic lung colonization by breast cancer cells in vivo.

cancer biology↗