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Myofibroblasts Derived from Hepatic Progenitor Cells Create the Tumor Microenvironment.

ABSTRACT: Hepatic progenitor cells (HPCs) appear in response to several types of chronic injury in the human and rodent liver that often develop into liver fibrosis, cirrhosis, and primary liver cancers. However, the contribution of HPCs to the pathogenesis and progression of such liver diseases remains controversial. HPCs are generally defined as cells that can differentiate into hepatocytes and cholangiocytes. In this study, however, we found that HPCs isolated from the chronically injured liver can also give rise to myofibroblasts as a third type of descendant. While myofibroblast differentiation from HPCs is not significant in culture, during tumor development, HPCs can contribute to the formation of the tumor microenvironment by producing abundant myofibroblasts that might form a niche for tumor growth and survival. Thus, HPCs can be redefined as cells with a potential for differentiation into myofibroblasts that is specifically activated during tumor formation.

SUBMITTER: Sekiya S

PROVIDER: S-EPMC5161752 | biostudies-literature | 2016 Dec

REPOSITORIES: biostudies-literature

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Myofibroblasts Derived from Hepatic Progenitor Cells Create the Tumor Microenvironment.

Sekiya Sayaka S Miura Shizuka S Matsuda-Ito Kanae K Suzuki Atsushi A

Stem cell reports 20161201 6

Hepatic progenitor cells (HPCs) appear in response to several types of chronic injury in the human and rodent liver that often develop into liver fibrosis, cirrhosis, and primary liver cancers. However, the contribution of HPCs to the pathogenesis and progression of such liver diseases remains controversial. HPCs are generally defined as cells that can differentiate into hepatocytes and cholangiocytes. In this study, however, we found that HPCs isolated from the chronically injured liver can als ...[more]

PMID: 27916538

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Project description:Hepatocellular carcinoma (HCC) generally occurs in the presence of chronic liver injury, often as a sequela of liver fibrosis. Hepatic progenitor cells (HPCs) are known to be capable of forming both hepatocytes and cholangiocytes in chronic liver injury, which are also considered a source of myofibroblasts and tumor-initiating cells, under carcinogenic circumstances. However, the underlying mechanisms that activate HPCs to give rise to HCC are still unclear. In current study, the correlation between HPCs activation and liver fibrosis and carcinogenesis was investigated in rats and human specimens. We analyzed the role of HPCs in tumorigenesis, by transplanting exogenous HPCs in a diethylnitrosamine-induced rat HCC model. Our data indicated that HPC activation correlated with hepatic fibrosis and hepatocarcinogenesis. We further found that exogenous HPC infusion promoted liver fibrosis and hepatocarcinogenesis, while lipopolysaccharides (LPS) played an important role in this process. However, results of our study indicated that LPS did not induce HPCs to form tumor in nude mice directly. Rather, LPS induced myofibroblast-like morphology in HPCs, which enhanced the tumorigenic potential of HPCs. Further experiments showed that LPS/Toll-like receptor 4 (TLR4) signaling mediated the differentiation of HPCs into myofibroblasts and enhanced the production of interleukin-6 (IL-6) and tumor necrosis factor-? (TNF-?), which led to the aberrant expression of Ras and p53 signaling pathways in HPCs, and finally, promoted the proliferation and malignant transformation of HPCs, by long non-coding RNA regulation. Besides, examination of HCC clinical samples demonstrated that IL-6 and TNF-? production correlated with HPC activation, hepatic fibrosis, and HCC recurrence. Our study indicates that both myofibroblasts and tumor cells are derived from HPCs. HPC-derived myofibroblasts create tumor microenvironment and contribute to the proliferation and malignant transformation of HPCs. Furthermore, LPS present in the chronic liver inflammation microenvironment might play an important role in hepatocarcinogenesis, by regulating the plastic potential of HPCs.

Project description:BACKGROUND & AIMS:Hepatic stellate cells (HSCs) contribute to desmoplasia and stiffness of liver metastases by differentiating into matrix-producing myofibroblasts. We investigated whether stiffness due to the presence of tumors increases activation of HSCs into myofibroblasts and their tumor-promoting effects, as well as the role of E1A binding protein p300, a histone acetyltransferase that regulates transcription, in these processes. METHODS:HSCs were isolated from liver tissues of patients, mice in which the p300 gene was flanked by 2 loxP sites (p300F/F mice), and p300+/+ mice (controls). The HSCs were placed on polyacrylamide gels with precisely defined stiffness, and their activation (differentiation into myofibroblasts) was assessed by immunofluorescence and immunoblot analyses for alpha-smooth muscle actin. In HSCs from mice, the p300 gene was disrupted by cre recombinase. In human HSCs, levels of p300 were knocked down with small hairpin RNAs or a mutant form of p300 that is not phosphorylated by AKT (p300S1834A) was overexpressed. Human HSCs were also cultured with inhibitors of p300 (C646), PI3K signaling to AKT (LY294002), or RHOA (C3 transferase) and effects on stiffness-induced activation were measured. RNA sequencing and chromatin immunoprecipitation-quantitative polymerase chain reaction were used to identify HSC genes that changed expression levels in response to stiffness. We measured effects of HSC-conditioned media on proliferation of HT29 colon cancer cells and growth of tumors following subcutaneous injection of these cells into mice. MC38 colon cancer cells were injected into portal veins of p300F/Fcre and control mice, and liver metastases were measured. p300F/Fcre and control mice were given intraperitoneal injections of CCl4 to induce liver fibrosis. Liver tissues were collected and analyzed by immunofluorescence, immunoblot, and histology. RESULTS:Substrate stiffness was sufficient to activate HSCs, leading to nuclear accumulation of p300. Disrupting p300 level or activity blocked stiffness-induced activation of HSCs. In HSCs, substrate stiffness activated AKT signaling via RHOA to induce phosphorylation of p300 at serine 1834; this caused p300 to translocate to the nucleus, where it up-regulated transcription of genes that increase activation of HSCs and metastasis, including CXCL12. MC38 cells, injected into portal veins, formed fewer metastases in livers of p300F/Fcre mice than control mice. Expression of p300 was increased in livers of mice following injection of CCl4; HSC activation and collagen deposition were reduced in livers of p300F/Fcre mice compared with control mice. CONCLUSIONS:In studies of mice, we found liver stiffness to activate HSC differentiation into myofibroblasts, which required nuclear accumulation of p300. p300 increases HSC expression of genes that promote metastasis.

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Myofibroblasts Derived from Hepatic Progenitor Cells Create the Tumor Microenvironment.

Publications

Myofibroblasts Derived from Hepatic Progenitor Cells Create the Tumor Microenvironment.

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