A potential requirement for Smad3 phosphorylation in Notch-mediated EMT in colon cancer.

Colorectal cancer (CRC) remains a challenging disease to treat due to several factors including stemness and epithelial to mesenchymal transition (EMT). Dysfunctional signaling pathways such as Notch and TGF-ß contribute to these phenomena. We previously found that cells expressing constitutively active Notch1 also had increased expression of Smad3, an important member of the TGF-ß signaling pathway. We hypothesized that Smad3, mediates the Notch-induced stemness and EMT observed in CRC cells. The human colorectal carcinoma cell line HCT-116, stably transduced with constitutively active Notch-1 (ICN) or a GFP-vector control was treated with different combinations of TGF-ß1, DAPT (a Notch inhibitor), or SIS3 (a Smad3 inhibitor). Western blot analysis was performed to determine the effects of Smad3 stimulation and inhibition on Notch and potential downstream EMT-related targets, CD44, Slug and Snail. Smad3 inhibition induced a decrease in Notch1 and Notch3 receptor expression and effectively inhibited CD44, Slug, and Snail expression. Colosphere forming ability was also reduced in cells with inhibited Smad3. These results indicate a key role of TGF-ß signaling in Notch1-induced tumorigenesis, and suggest a potential use for Smad3 inhibitors in combination with Notch1 inhibitors that are already in use for CRC treatments.

Infrared Thermographic Analysis of Surface Temperature of the Hands During Exposure to Normobaric Hypoxia.

Frostbite and other cold-related injuries commonly develop during prolonged exposure to the low environmental temperatures of polar and mountainous regions. Hypoxia is a potent sympathetic stimulus that causes vasoconstriction of the peripheral blood vessels, which may further compound the risk of developing a cold-related injury during high-altitude exposure. To investigate this, we utilized portable infrared thermographic technology to quantitatively measure changes in the surface temperature of the hands during exposure to increasing levels of normobaric hypoxia in a temperature-controlled high-altitude simulation. Surface temperature was assessed at four anatomical locations on both the left and right hands in a cohort of 10 healthy male participants at a series of predetermined levels of hypoxia (0.20 fraction of inspired oxygen [FIO2] [pre- and postexposure], 0.172 FIO2, 0.145 FIO2, 0.128 FIO2). Thermographic analysis revealed an overall decrease in peripheral temperature across the anatomical regions of the hands as the hypoxic stimulus increased, with statistically significant reductions observed at all four anatomical sites during exposure to 0.128 FIO2 (p < 0.05). These findings demonstrate that portable infrared thermography can be used to detect reductions in peripheral surface body temperature during exposure to normobaric hypoxia.