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Background: Although fine-needle aspiration (FNA) biopsy of thyroid nodules is very sensitive in detecting thyroid malignancy, it remains ambiguous in 20-30% of cases. Current biomarkers for thyroid cancer lack either the sensitivity or specificity to substantially address this clinical problem. The aim of this study was to investigate the gene expression patterns of human telomerase reverse transcriptase (hTERT) alternative splice variants in benign and malignant thyroid tumors in an attempt to find a more reliable biomarker in the differential diagnosis of thyroid nodules. Methods: One hundred and thirty-three thyroid tumors from eight histopathological tumor types were collected from patients undergoing thyroid surgery at Johns Hopkins Hospital. Gene expression patterns of hTERT alternative splice variants were investigated in the tumors by nested reverse transcriptase-PCR. Telomerase enzyme activity was evaluated in a subset of 16 samples associated with the different hTERT patterns. Association of c-myc expression and hTERT patterns was also examined. Results: Malignant thyroid tumors exhibited a greater proportion of the active full-length hTERT transcript (0.57 AE 0.15) than inactive splice variants, a À (0.13 AE 0.02), or b À =a À b À deletion transcripts (0.30 AE 0.11; p < 0.001). The opposite was observed in benign tumors, which exhibited greater proportions of b À =a À b À deletion transcripts (0.64 AE 0.08) than either the full-length (0.19 AE 0.06) or a À deletion transcripts (0.17 AE 0.02; p < 0.001). Similar results were observed among a diagnostically challenging subset of 50 thyroid tumors that were suspicious for malignancy on FNA. Further, increased telomerase enzymatic activity was only associated with expression of the full-length hTERT isoform. In contrast, c-myc expression, which has been implicated in hTERT regulation, correlated with overall hTERT transcription without specificity for expression of the full-length isoform. Conclusions: These differences in gene expression patterns of hTERT alternative splice variants may provide a useful adjunct to FNA diagnosis of suspicious thyroid tumors.

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The dire effects of cancer-induced cachexia undermine treatment and contribute to decreased survival rates. Therapeutic options for this syndrome are limited, and therefore efforts to identify signs of precachexia in cancer patients are necessary for early intervention. The applications of molecular and functional imaging that would enable a whole-body “holistic” approach to this problem may lead to new insights and advances for diagnosis and treatment of this syndrome. Here we have developed a myoblast optical reporter system with the purpose of identifying early cachectic events. We generated a myoblast cell line expressing a dual tdTomato:GFP construct that was grafted onto the muscle of mice bearing human pancreatic cancer xenografts to provide noninvasive live imaging of events associated with cancer-induced cachexia (i.e., weight loss). Real time optical imaging detected a strong tdTomato fluorescent signal from skeletal muscle grafts in mice with weight loses of only 1.2 to 2.7% and tumor burdens of only ~79 to ~170 mm3. Weight loss in cachectic animals was also associated with a depletion of lipid, cholesterol, valine, and alanine levels, which may provide informative biomarkers of cachexia. Taken together, our findings demonstrate the utility of a reporter system that is capable of tracking tumor-induced weight loss, an early marker of cachexia. Future studies incorporating resected tissue from human pancreatic ductal adenocarcinoma (PDAC) into a reporter-carrying mouse may be able to provide a risk assessment of cachexia with possible implications for therapeutic development.

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<p>Supplemental Figure S2. Weight loss and tdT fluorescence induction is dependent on tumor type in an orthotopic model of pancreatic cancer.</p>

<p>Supplemental Figure S3. Induction of tdT fluorescence occurred at an early time during tumor growth and was dependent on the tumor type in the s.c. model of pancreatic cancer.</p>