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Hedgehog pathway activation and epithelial-to-mesenchymal transitions during myofibroblastic transformation of rat hepatic cells in culture and cirrhosis.

ABSTRACT: Myofibroblastic hepatic stellate cells (MF-HSC) are derived from quiescent hepatic stellate cells (Q-HSC). Q-HSC express certain epithelial cell markers and have been reported to form junctional complexes similar to epithelial cells. We have shown that Hedgehog (Hh) signaling plays a key role in HSC growth. Because Hh ligands regulate epithelial-to-mesenchymal transition (EMT), we determined whether Q-HSC express EMT markers and then assessed whether these markers change as Q-HSC transition into MF-HSC and whether the process is modulated by Hh signaling. Q-HSC were isolated from healthy livers and cultured to promote myofibroblastic transition. Changes in mRNA and protein expression of epithelial and mesenchymal markers, Hh ligands, and target genes were monitored in HSC treated with and without cyclopamine (an Hh inhibitor). Studies were repeated in primary human HSC and clonally derived HSC from a cirrhotic rat. Q-HSC activation in vitro (culture) and in vivo (CCl(4)-induced cirrhosis) resulted in decreased expression of Hh-interacting protein (Hhip, an Hh antagonist), the EMT inhibitors bone morphogenic protein (BMP-7) and inhibitor of differentiation (Id2), the adherens junction component E-cadherin, and epithelial keratins 7 and 19 and increased expression of Gli2 (an Hh target gene) and mesenchymal markers, including the mesenchyme-associated transcription factors Lhx2 and Msx2, the myofibroblast marker alpha-smooth muscle actin, and matrix molecules such as collagen. Cyclopamine reverted myofibroblastic transition, reducing mesenchymal gene expression while increasing epithelial markers in rodent and human HSC. We conclude that Hh signaling plays a key role in transition of Q-HSC into MF-HSC. Our findings suggest that Q-HSC are capable of transitioning between epithelial and mesenchymal fates.

SUBMITTER: Choi SS

PROVIDER: S-EPMC2850083 | biostudies-literature | 2009 Dec

REPOSITORIES: biostudies-literature

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Hedgehog pathway activation and epithelial-to-mesenchymal transitions during myofibroblastic transformation of rat hepatic cells in culture and cirrhosis.

Choi Steve S SS Omenetti Alessia A Witek Rafal P RP Moylan Cynthia A CA Syn Wing-Kin WK Jung Youngmi Y Yang Liu L Sudan Debra L DL Sicklick Jason K JK Michelotti Gregory A GA Rojkind Marcos M Diehl Anna Mae AM

American journal of physiology. Gastrointestinal and liver physiology 20091008 6

Myofibroblastic hepatic stellate cells (MF-HSC) are derived from quiescent hepatic stellate cells (Q-HSC). Q-HSC express certain epithelial cell markers and have been reported to form junctional complexes similar to epithelial cells. We have shown that Hedgehog (Hh) signaling plays a key role in HSC growth. Because Hh ligands regulate epithelial-to-mesenchymal transition (EMT), we determined whether Q-HSC express EMT markers and then assessed whether these markers change as Q-HSC transition into ...[more]

PMID: 19815628

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Project description:Mutant p53 is not only deficient in tumor suppression but also acquires additional activity, called gain of function. Mutant p53 gain of function is recapitulated in knock-in mice that carry one null allele and one mutant allele of the p53 gene. These knock-in mice develop aggressive tumors compared with p53-null mice. Recently, we and others showed that tumor cells carrying a mutant p53 are addicted to the mutant for cell survival and resistance to DNA damage. To further define mutant p53 gain of function, we used the MCF-10A three-dimensional model of mammary morphogenesis. MCF-10A cells in three-dimensional culture undergo a series of morphological changes and form polarized and growth-arrested spheroids with hollow lumen, which resembles normal glandular architectures in vivo. Here, we found that endogenous wild-type p53 in MCF-10A cells was not required for acinus formation, but knockdown of endogenous wild-type p53 (p53-KD) led to partial clearance of cells in the lumen due to decreased apoptosis. Consistent with this, p53-KD altered expression patterns of the cell adhesion molecule E-cadherin, the cytoskeletal marker ?-catenin, and the extracellular matrix protein laminin V. We also found that ectopic expression of the mutant G245S led to a phenotype similar to p53-KD, whereas a combination of ectopic expression of siRNA-resistant G245S with p53-KD led to a less cleared lumen. In contrast, ectopic expression of mutant R248W, R175H, and R273H disrupted normal acinus architectures with filled lumen and led to formation of irregular and multiacinus structures regardless of p53-KD. In addition, these mutants altered normal expression patterns and/or levels of E-cadherin, ?-catenin, laminin V, and tight junction marker ZO-1. Furthermore, epithelial-to-mesenchymal transitions (EMT) markers, Snail, Slug, and Twist, were highly induced by mutant p53 and/or p53-KD. Together, we postulate that EMT represents a mutant p53 gain of function and mutant p53 alters cell polarity via EMT.

Dataset Information

Hedgehog pathway activation and epithelial-to-mesenchymal transitions during myofibroblastic transformation of rat hepatic cells in culture and cirrhosis.

Publications

Hedgehog pathway activation and epithelial-to-mesenchymal transitions during myofibroblastic transformation of rat hepatic cells in culture and cirrhosis.

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