Thyroid cancer is the most common endocrine malignancy. Anaplastic thyroid cancer is one of the most aggressive thyroid tumors. It is known that activation of oncogenes and/or inactivation of tumor suppressor genes in tumor cells promotes tumorigenesis. The microenvironment of the tumor also plays a key role on cancer development and progression in a variety of tumors. However, the mechanisms by which tumor-stroma crosstalk in thyroid cancer remains poorly characterized. In this study we aimed to understand how interactions between fibroblasts and anaplastic thyroid cancer cells contribute to thyroid carcinogenesis. We first characterized the phenotypic changes of human fibroblasts in vitro through co-cultures by using transwells as well as by using anaplastic thyroid cancer cells-derived conditioned media. We found that fibroblasts acquired an activated phenotype or also known as cancer-associated fibroblast phenotype after being in contact with soluble factors secreted from anaplastic thyroid cancer cells, compared to the fibroblasts in mono-cultures. All the changes were partly mediated through Src/Akt activation. Treatment with the antioxidant N-acetyl-cysteine reversed in part the metabolic phenotype of activated fibroblasts. Remarkably, conditioned media obtained from these activated fibroblasts promoted cell proliferation and invasion of follicular thyroid cancer cell line, FTC-133 cells. Thus, a reciprocal and dynamic interaction exists between tumor and stromal cells, which results in the promotion of thyroid tumorigenesis. The present studies have advanced the understanding of the molecular basis of tumor-stroma communications, enabling identification and targeting of tumor-supportive mechanisms for novel treatment modalities.

Bidirectional cross-talk between the neuroendocrine and immune systems orchestrates immune responses in both physiologic and pathologic settings. In this study, we provide in vivo evidence of a critical role for the thyroid hormone triiodothyronine (T3) in controlling the maturation and antitumor functions of dendritic cells (DC). We used a thyroid hormone receptor (TR) b mutant mouse (TRbPV) to establish the relevance of the T3-TRb system in vivo. In this model, TRb signaling endowed DCs with the ability to stimulate antigen-specific cytotoxic T-cell responses during tumor development. T3 binding to TRb increased DC viability and augmented DC migration to lymph nodes. Moreover, T3 stimulated the ability of DCs to cross-present antigens and to stimulate cytotoxic T-cell responses. In a B16-OVA mouse model of melanoma, vaccination with T3-stimulated DCs inhibited tumor growth and prolonged host survival, in part by promoting the generation of IFNg-producing CD8 þ T cells.Overall, our results establish an adjuvant effect of T3-TRb signaling in DCs, suggesting an immediately translatable method to empower DC vaccination approaches for cancer immunotherapy. Cancer Res; 75(7); 1265-74. Ó2015 AACR.

Glutamine behaves as a key nutrient for tumors and rapidly dividing cells. Glutaminase is the main glutamine-utilizing enzyme in these cells, and its activity correlates with glutamine consumption and growth rate. We have carried out the antisense L-type glutaminase inhibition in human MCF7 breast cancer cells, in order to study its effect on the hexosamine pathway and the pattern of protein O-glycosylation. The antisense mRNA glutaminase expressing cells, named ORF19, presented a 50% lower proliferation rate than parental cells, showing a more differentiated phenotype. ORF19 cells had an 80% reduction in glutamine:fructose-6-P amidotransferase activity, which is the rate-limiting step of the hexosamine pathway. Although the overall cellular protein O-glycosylation did not change, the O-glycosylation status of several key proteins was altered. O-glycosylation of O-GlcNAc transferase (OGT), the enzyme that links N-acetylglucosamine to proteins, was fivefold lower in ORF19 than in wild type cells. Inhibition of glutaminase also provoked a 10-fold increase in Sp1 expression, and a significant decrease in the ratio of O-glycosylated to total protein for both Sp1 and the Rpt2 proteasome component. These changes were accompanied by a higher Sp1 transcriptional activity. Proteome analysis of O-glycosylated proteins permitted the detection of two new OGT target proteins: the chaperonin TCP-1 theta and the oncogene Ets-related protein isoform 7. Taken together, our results support the hexosamine pathway and the O-glycosylation of proteins being a sensor mechanism of the nutritional and energetic states of the cell.