Lactate Dehydrogenase A as a Potential New Biomarker for Thyroid Cancer

Background@#Several cancers show increased levels of lactate dehydrogenase A (LDHA), which are associated with cancer progression. However, it remains unclear whether LDHA levels are associated with papillary thyroid cancer (PTC) aggressiveness or with the presence of the PTC prognostic marker, the BRAFV600E mutation. This study aimed to evaluate the potential of LDHA as a PTC prognostic marker. @*Methods@#LDHA expression was examined in 83 PTC tissue specimens by immunohistochemistry. Human thyroid cell lines were genetically manipulated to overexpress BRAFV600E or were treated with a BRAF-specific short hairpin RNA (shBRAF), whose effects on LDHA expression were evaluated by Western blotting. Data from 465 PTC patients were obtained from The Cancer Genome Atlas (TCGA) database and analyzed to validate the in vitro results. @*Results@#LDHA was aberrantly overexpressed in PTC. Intense immunostaining for LDHA was observed in PTC specimens carrying mutated BRAF, whereas the intensity was less in wild-type BRAF samples. Overexpression of BRAFV600E resulted in LDHA upregulation, whereas treatment with shBRAF downregulated LDHA in human thyroid cell lines. Furthermore, LDHA mRNA expression was significantly elevated and associated with BRAFV600E expression in thyroid cancer tissues from TCGA database. Additionally, LDHA overexpression was found to be correlated with aggressive clinical features of PTC, such as lymph node metastases and advanced tumor stages. @*Conclusion@#LDHA overexpression is associated with the BRAFV600E mutation and an aggressive PTC behavior. Therefore, LDHA may serve as a biomarker and therapeutic target in PTC.

The functional role of the CARM1-SNF5 complex and its associated HMT activity in transcriptional activation by thyroid hormone receptor

We have investigated the function and mechanisms of the CARM1-SNF5 complex in T3-dependent transcriptional activation. Using specific small interfering RNAs (siRNA) to knock down coactivators in HeLa alpha2 cells, we found that coactivator associated arginine methyltransferase 1 (CARM1) and SWI/SNF complex component 5 (SNF5) are important for T3-dependent transcriptional activation. The CARM1- SWI/SNF chromatin remodeling complex serves as a mechanism for the rapid reversal of H3-K9 methylation. Importantly, siRNA treatment against CARM1 and/or SNF5 increased the recruitment of HMTase G9a to the type 1 deiodinase (D1) promoter even with T3. Knocking- down either CARM1 or SNF5 also inhibited the down- regulation of histone macroH2A, which is correlated with transcriptional activation. Finally, knocking down CARM1 and SNF5 by siRNA impaired the association of these coactivators to the D1 promoter, suggesting functional importance of CARM1- SNF5 complex in T3-dependent transcriptional activation.

The Combination of TRAIL Treatment and Cancer Cell Selective Expression of TRAIL-Death Receptor DR4 Induces Cell Death in TRAIL-Resistant Cancer Cells

The human telomerase reverse transcriptase (hTERT) promoter can be used for the tumor-specific expression of transgenes in order to induce selective cancer cell death. The hTERT core promoter is active in cancer cells but not in normal cells. To examine whether the combination of TNF-related apoptosis inducing ligand (TRAIL) treatment and cancer cell-selective expression of the TRAIL-death receptor could induce cell death in TRAIL-resistant cancer cells, we generated a death receptor-4 (DR4)-expressing adenovirus (Ad-hTERT-DR4), in which the expression of DR4 is driven by the hTERT promoter. Upon infection, DR4 expression was slightly increased in cancer cell lines, and cell death was observed in TRAIL-resistant cancer cell lines but not in normal human cells when DR4 infection was combined with TRAIL treatment. We also generated an adenovirus that expresses a secretable isoleucine zipper (ILZ)-fused, extracellular portion of TRAIL (Ad-ILZ-TRAIL). In cells infected with Ad-ILZ-TRAIL, TRAIL was expressed, secreted, oligomerized and biologically active in the induction of apoptosis in TRAIL-sensitive cancer cells. When Ad-hTERT-DR4 infected TRAIL-resistant HCE4 cells and Ad-ILZ-TRAIL infected TRAIL-resistant HCE7 cells were co-cultured, cell deaths were evident 24 h after co-culture. Taken together, our results reveal that the combination of TRAIL and cancer cell-specific expression of DR4 has the potential to overcome the resistance of cancer cells to TRAIL without inducing significant cell death in normal cells.