24-Dehydrocholesterol reductase promotes the growth of breast cancer stem-like cells through the Hedgehog pathway.

Cholesterol is a risk factor for breast cancer. However, it is still unclear whether the cholesterol biosynthesis pathway plays any significant role in breast carcinogenesis. 24-Dehydrocholesterol reductase (DHCR24) is a key enzyme in the cholesterol synthesis pathway. Although DHCR24 is reported to have different functions in different cancers, it is not clear whether DHCR24 is involved in breast cancer. In this study, we found that DHCR24 expression was higher in breast cancer especially in luminal and HER2 positive breast cancer tissues compared with normal breast. Changes in DHCR24 expression altered cellular cholesterol content without affecting the adherent growth of breast cancer cells. However, DHCR24 knockdown reduced whereas DHCR24 overexpression enhanced breast cancer stem-like cell populations such as mammosphere and aldehyde dehydrogenase positive cell numbers. In addition, DHCR24 overexpression increased the expression of the Hedgehog pathway-regulated genes. Treating DHCR24 overexpressing breast cancer cell lines with the Hedgehog pathway inhibitor GANT61 blocked DHCR24-induced mammosphere growth and increased mRNA levels of the Hedgehog regulated genes. Furthermore, expression of a constitutively activated mutant of Smoothened, a key hedgehog signal transducer, rescued the decreases in mammosphere growth and Hedgehog regulated gene expression induced by knockdown of DHCR24. These results indicate that DHCR24 promotes the growth of breast cancer stem-like cells in part through enhancing the Hedgehog signaling pathway. Our data suggest that cholesterol contribute to breast carcinogenesis by enhancing Hedgehog signaling and cancer stem-like cell populations. Enzymes including DHCR24 involved in cholesterol biosynthesis should be considered as potential treatment targets for breast cancer.

Gab2 promotes cancer stem cell like properties and metastatic growth of ovarian cancer via downregulation of miR-200c.

Scaffolding adaptor Gab2 is overexpressed in a subset of high-grade ovarian cancer. Our published work shows that Gab2 via PI3K enhances migratory behaviors and epithelial to mesenchymal transition (EMT) features of ovarian cancer cells in vitro. However, it is still unclear how Gab2/PI3K pathway reuglates EMT characteristics and whether Gab2 promotes the growth of ovarian cancer stem cell (CSC)-like population and metastatic growth. In this study, we examined the effects of Gab2 expression on CSC-like cell growth using Aldefluor and tumorshpere assays commonly used for assessing ovarian cancer cells with CSC properties. Gab2 overexpression increased the number of ALDH+ cells and tumorsphere formation in two different ovarian cancer cell lines OVCAR5 and OVCAR8, whereas knockdown of Gab2 decreased the number of ALDH+ cells and tumorsphere formation in Caov-3 cells. Furthermore, Gab2 promoted metastatic tumor growth of OVCAR5 in nude mice. Mechanistically, we uncovered that Gab2 via PI3K specifically inhibited miR-200c expression. miR-200c downregulation contributed to the Gab2-enhanced cell migratory behaviors, EMT properties, and the expansion of ALDH+ cells and tumorspheres. Furthermore, Gab2 promoted CD44 expression and cell migration/invasion through miR-200c downregulation. Our findings support a model that Gab2-PI3K pathway via miR-200c downregulation promotes CD44 expression, EMT characteristics, and CSC-like cell growth. Therapies involving miR-200c or targeting CD44 should help treat ovarian cancer with high Gab2 expression.

Administration of bone marrow stromal cells in sepsis attenuates sepsis-related coagulopathy.

INTRODUCTION: Coagulopathy plays an important role in sepsis. The aim of this study was to determine whether bone marrow stromal cell (BMSC) administration could attenuate coagulopathy in sepsis. MATERIALS AND METHODS: In vitro: endothelial cells were cultured with/without BMSCs for 6 h following LPS stimulation and were collected for thrombomodulin (TM) and endothelial protein C receptor (EPCR) measurements. In vivo: Thirty-six mice were randomized into sham, sepsis, and sepsis + BMSC groups (n = 12 each group). Sepsis was induced through cecal ligation and puncture (CLP). BMSC infusion was started at 6 h after CLP. Lung tissues and plasma samples were collected at 24 h after CLP for enzyme-linked immunosorbent assay (ELISA), quantitative real-time RT-PCR, western blot, and immunohistochemistry analysis. RESULTS: In vitro: BMSCs attenuated the decrease in TM and EPCR mRNA and protein expression levels in LPS-stimulated endothelial cells. In vivo: BMSC treatment decreased lung injury and mesenteric perfusion impairment, and ameliorated coagulopathy, as suggested by the reduction in elevated TF, vWF, and TAT circulation levels. BMSC infusion decreased TF mRNA transcription and protein expression levels in lung tissues, and increased TM and EPCR mRNA transcription and expression levels. DISCUSSION: BMSC administration attenuated coagulopathy, and decreased lung injury and mesenteric perfusion impairment in sepsis. Key messages BMSCs increased the expression of TM and EPCR from endothelium cells exposed to LPS in vitro. BMSC treatment attenuated lung injury and coagulopathy in the mice cecal ligation and puncture (CLP) model. BMSC administration-attenuated coagulopathy is related to the reduced expression of TF and increased expression of TM and EPCR.