Patient-derived skeletal dysplasia induced pluripotent stem cells display abnormal chondrogenic marker expression and regulation by BMP2 and TGFß1.

Skeletal dysplasias (SDs) are caused by abnormal chondrogenesis during cartilage growth plate differentiation. To study early stages of aberrant cartilage formation in vitro, we generated the first induced pluripotent stem cells (iPSCs) from fibroblasts of an SD patient with a lethal form of metatropic dysplasia, caused by a dominant mutation (I604M) in the calcium channel gene TRPV4. When micromasses were grown in chondrogenic differentiation conditions and compared with control iPSCs, mutant TRPV4-iPSCs showed significantly (P<0.05) decreased expression by quantitative real-time polymerase chain reaction of COL2A1 (IIA and IIB forms), SOX9, Aggrecan, COL10A1, and RUNX2, all of which are cartilage growth plate markers. We found that stimulation with BMP2, but not TGFß1, up-regulated COL2A1 (IIA and IIB) and SOX9 gene expression, only in control iPSCs. COL2A1 (Collagen II) expression data were confirmed at the protein level by western blot and immunofluorescence microscopy. TRPV4-iPSCs showed only focal areas of Alcian blue stain for proteoglycans, while in control iPSCs the stain was seen throughout the micromass sample. Similar staining patterns were found in neonatal cartilage from control and patient samples. We also found that COL1A1 (Collagen I), a marker of osteogenic differentiation, was significantly (P<0.05) up-regulated at the mRNA level in TRPV4-iPSCs when compared with the control, and confirmed at the protein level. Collagen I expression in the TRPV4 model also may correlate with abnormal staining patterns seen in patient tissues. This study demonstrates that an iPSC model can recapitulate normal chondrogenesis and that mutant TRPV4-iPSCs reflect molecular evidence of aberrant chondrogenic developmental processes, which could be used to design therapeutic approaches for disorders of cartilage.

Functional analysis of microRNAs in human hepatocellular cancer stem cells.

MicroRNAs are endogenous small non-coding RNAs that regulate gene expression and cancer development. A rare population of hepatocellular cancer stem cells (HSCs) holds the extensive proliferative and self-renewal potential necessary to form a liver tumour. We postulated that specific transcriptional factors might regulate the expression of microRNAs and subsequently modulate the expression of gene products involved in phenotypic characteristics of HSCs. We evaluated the expression of microRNA in human HSCs by microarray profiling, and defined the target genes and functional effects of two groups of microRNA regulated by IL-6 and transcriptional factor Twist. A subset of highly chemoresistant and invasive HSCs was screened with aberrant expressions of cytokine IL-6 and Twist. We demonstrated that conserved let-7 and miR-181 family members were up-regulated in HSCs by global microarray-based microRNA profiling followed by validation with real-time polymerase chain reaction. Importantly, inhibition of let-7 increases the chemosensitivity of HSCs to sorafenib and doxorubicin whereas silencing of miR-181 led to a reduction in HSCs motility and invasion. Knocking down IL-6 and Twist in HSCs significantly reduced let-7 and miR-181 expression and subsequently inhibited chemoresistance and cell invasion. We showed that let-7 directly targets SOCS-1 and caspase-3, whereas miR-181 directly targets RASSF1A, TIMP3 as well as nemo-like kinase (NLK). In conclusion, alterations of IL-6- and Twist-regulated microRNA expression in HSCs play a part in tumour spreading and responsiveness to chemotherapy. Our results define a novel regulatory mechanism of let-7/miR-181s suggesting that let-7 and miR-181 may be molecular targets for eradication of hepatocellular malignancies.

Resveratrol inhibits pancreatic cancer stem cell characteristics in human and KrasG12D transgenic mice by inhibiting pluripotency maintaining factors and epithelial-mesenchymal transition.

BACKGROUND: Cancer stem cells (CSCs) can proliferate and self-renew extensively due to their ability to express anti-apoptotic and drug resistant proteins, thus sustaining tumor growth. Therefore, the strategy to eradicate CSCs might have significant clinical implications. The objectives of this study were to examine the molecular mechanisms by which resveratrol inhibits stem cell characteristics of pancreatic CSCs derived from human primary tumors and Kras(G12D) transgenic mice. METHODOLOGY/PRINCIPAL FINDINGS: Human pancreatic CSCs (CD133(+)CD44(+)CD24(+)ESA(+)) are highly tumorigenic and form subcutaneous tumors in NOD/SCID mice. Human pancreatic CSCs expressing high levels of CD133, CD24, CD44, ESA, and aldehyde dehydrogenase also express significantly more Nanog, Oct-4, Notch1, MDR1 and ABCG2 than normal pancreatic tissues and primary pancreatic cancer cells. Similarly, CSCs from Kras(G12D) mice express significantly higher levels of Nanog and Oct-4 than pancreatic tissues from Pdx-Cre mice. Resveratrol inhibits the growth (size and weight) and development (PanIN lesions) of pancreatic cancer in Kras(G12D) mice. Resveratrol inhibits the self-renewal capacity of pancreatic CSCs derived from human primary tumors and Kras(G12D) mice. Resveratrol induces apoptosis by activating capase-3/7 and inhibiting the expression of Bcl-2 and XIAP in human CSCs. Resveratrol inhibits pluripotency maintaining factors (Nanog, Sox-2, c-Myc and Oct-4) and drug resistance gene ABCG2 in CSCs. Inhibition of Nanog by shRNA enhances the inhibitory effects of resveratrol on self-renewal capacity of CSCs. Finally, resveratrol inhibits CSC's migration and invasion and markers of epithelial-mesenchymal transition (Zeb-1, Slug and Snail). CONCLUSIONS/SIGNIFICANCE: These data suggest that resveratrol inhibits pancreatic cancer stem cell characteristics in human and Kras(G12D) transgenic mice by inhibiting pluripotency maintaining factors and epithelial-mesenchymal transition. In conclusion, resveratrol can be used for the management of pancreatic cancer.