The stress-activated protein kinase pathway and the expression of stanniocalcin-1 are regulated by miR-146b-5p in papillary thyroid carcinogenesis.

Papillary thyroid cancer (PTC) is the most common type of thyroid cancer. Deciphering the pathophysiological mechanisms that contribute to PTC development is essential to the discovery of optimal diagnostic and therapeutic approaches. MiR-146b-5p has been identified as a cancer-associated microRNA highly up-regulated in PTC. This study explores the hypothesis that miR-146b-5p contributes to papillary thyroid carcinogenesis through regulation of cell signaling pathways in a manner that overcomes the cellular growth suppressive events and provides survival advantage. The effect of miR-146b-5p inhibition on major cancer related signaling pathways and expression of Stanniocalcin-1 (STC1), an emerging molecule associated with stress response and carcinogenesis, was tested in cultured primary thyroid cells using luciferase reporter assays, quantitative real-time PCR, immunofluorescence staining, and flow cytometry. Our results demonstrated that miR-146b-5p inhibits the JNK/AP1 pathway activity and down-regulates the expression of STC-1 in thyroid-cultured cells and in thyroid tissue samples. In the presence of miR-146b-5p, PTC cells were resistant to cell death in response to oxidative stress. This is a novel report that miR-146b-5p directly targets STC1 and regulates the activity of JNK/AP1 pathway. Considering the importance of the JNK/AP1 pathway and STC1 in mediating many physiological and pathological processes like apoptosis, stress response and cellular metabolism, a biological regulator of these pathways would have a great scientific and clinical significance.

Down-regulation of the human major histocompatibility complex class I chain-related gene A (MICA) and its receptor is mediated by microRNA-146b-5p and is a potential mechanism of immunoediting in papillary thyroid carcinoma.

Immune escape is one of the main reasons for the rapid progression of cancer and the poor efficacy of immunotherapy. Papillary thyroid cancer (PTC) is usually accompanied by intra-tumoral lymphocytic infiltration. The mechanisms regulating this tumor associated immune response or its evasion are not well understood. The major histocompatibility complex class I chain-related proteins A (MICA) and its receptor the natural killer group 2 member D (NKG2D) are major executers of the anti-tumor defense. This work aimed to study the expression and regulation of MICA-NKG2D and its association with the lymphocytic infiltration and miRNAs in PTC. Expression of MICA and NKG2D in thyroid tissues, and in cultured primary thyroid cancer cells and lymphocytes transfected with miR-146b-5p inhibitor/mimic was tested by RT-PCR. Results were confirmed by immunofluorescence staining and confocal microscopy. MICA is expressed in malignant and benign thyroid tissues with no association with aggressive behavior. Expression of MICA and NKG2D in PTC is concomitant with the presence of tumor associated lymphocytic response and is regulated by miR-146b-5p. MiR-146b-5p indirectly downregulates NKG2D expression in cancer cells and in lymphocytes. Overexpression of miR-146b-5p in PTC down-regulates MICA expression possibly to reduce the immunogenicity of the tumor cells. Targeting of the MICA-NKG2D axis by miR-146b-5p might be one of the ways adopted by thyroid cancer cells to aid the tumor in evading the immune response. The importance of our findings resides in the potential therapeutic use of MICA, NKG2D and miRNA-146b-5p as targets or modulators to enable the immune response against cancer.

Toll-like receptor 4-mediated immune stress in pregnant rats activates STAT3 in the fetal brain: role of interleukin-6.

BACKGROUND: Prenatal exposure to pathogens induces long lasting effect on brain function and plasticity. It is unclear how maternal immune stress impacts fetal brain development. Immune challenged pregnant rats induce the production of inflammatory cytokines including tumor necrosis factor (TNF)α, interleukin (IL)1ß, and IL-6. IL-6 crosses the placenta but its mechanism of action on fetal brain is unclear. METHODS: Gestation day 15 (GD15) rats were given a single injection of lipopolysaccharide (LPS) (100 µg/kg) in the presence or the absence of an IL-6 neutralizing antibody (IL-6Ab, 10 µg/kg). The activation of the intracellular signal of IL-6; signal transducer and activator of transcription (STAT3) and levels of glucocorticoids (GCs) were monitored in fetal brains. RESULTS: LPS administration to GD15 rats significantly increased the phosphorylation levels of STAT3 in fetal brains. Such activation was blunted by IL-6Ab. LPS induced a significant rise in GCs in the plasma of dams but not in fetal brains. IL-6Ab significantly reduced LPS-induced GCs in maternal plasma. CONCLUSION: Toll-like receptor 4 (TLR4)-induced activation of the maternal innate immune system affects fetal brains likely via the mobilization of IL-6/STAT3 pathway. In contrast, TLR4-stimulated maternal GCs release is less likely to play a significant role in fetal brain development.

Role of Na+/H+ exchanger in resveratrol-induced growth inhibition of human breast cancer cells.

Cancer cells maintain low intracellular pH [pHi]; therefore, it is likely that resveratrol [RSVL] inhibits cell growth through interference with regulation of pHi. Na-H exchanger [NHE] regulates pHi and NaCl uptake. In this study, we investigated a putative role of NHE-1 and NHE-3 isoforms in the RSVL-induced cell death using MDA-MB-231 estrogen receptor-negative [ER-] and MCF-7 [ER+] human breast cancer cell lines. ECL Western blot analysis and fluorescence morphometeric analysis were used. Cell viability and counting were performed using standard procedures. RSVL caused a dose- and time-dependent induction of NHE-1 and NHE-3 proteins in both cancer cell lines as shown by ECL Western blot analysis and fluorescence measurement. Interestingly, the level of actin, an internal control, remains unaltered. Thus, it is concluded that RSVL-inhibited cell growth and viability, increased cell size, and volume along with an increased apoptotic activity are due to the induction of NHE-1 and NHE-3 isoforms in the present breast cancer cell lines. Induction of NHE will increase the uptake of NaCl and decrease pHi leading to disturbance in Ca(2+) homeostasis, which is responsible for cell death.