Hepatocyte nuclear factor-1 as marker of epithelial phenotype reveals marrow-derived hepatocytes, but not duct cells, after liver injury in mice

The impact of hepatocyte nuclear factor-1α on liver malignancies and cell stemness with metabolic consequences

Hepatocyte nuclear factor-1 alpha (HNF-1α) is a transcription factor expressed predominantly in the liver among other organs. Structurally, it contains POU-homeodomain that binds to DNA and form proteins that help in maintaining cellular homeostasis, controlling metabolism, and differentiating cell lineages. Scientific research over the period of three decades has reported it as an important player in various liver malignancies such as hepatocellular cancers (HCCs), hepatocellular adenoma (HA), and a more specific HNF-1α-inactivated human hepatocellular adenoma (H-HCAs). Abundant clinical and rodent data have noted the downregulation of HNF-1α in parallel with liver malignancies. It is also interesting to notice that the co-occurrence of mutated HNF-1α expression and hepatic carcinomas transpires typically along with metabolic repercussion. Moreover, scientific data implies that HNF-1α exerts its effects on cell stemness and hence can indirectly impact liver malignancies and metabolic functioning. The effects of HNF-1α on cell stemness present a future opportunity to explore a possible and potential breakthrough. Although the mechanism through which inactivated HNF-1α leads to hepatic malignancies remain largely obscure, several key signal molecules or pathways, including TNF-α, SHP-1, CDH17, SIRT, and MIA-2, have been reported to take part in the regulations of HNF-1α. It can be concluded from the present scientific data that HNF-1α has a great potential to serve as a target for liver malignancies and cell stemness.

Apolipoprotein M could inhibit growth and metastasis of SMMC7721 cells via vitamin D receptor signaling

Objective: Hepatocellular carcinoma (HCC) is one of the most common malignant tumors with high mortality-to-incidence ratios. Apolipoprotein M (ApoM), a member of the apolipoprotein family, is mainly synthesized in the liver, whereas its role in HCC has not been elucidated. Here, we examined the effect of ApoM on the biological behavior of HCC cells and the possible mechanisms. Methods: We used CRISPR/Cas9 technology to knock out ApoM in SMMC7721 cells. Differentially expressed genes before and after ApoM knockout (KO) were analyzed by GeneChip microarrays and confirmed by qRT-PCR. Cell assays of proliferation, apoptosis, migration and invasion were performed in SMMC7721 cells, and the expression of epithelial-mesenchymal transition (EMT) markers was performed by western blot. And we performed functional recovery experiments by overexpressing vitamin D receptor (VDR) in SMMC7721. Results: The ApoM-KO SMMC7721 cell line was successfully constructed using the CRISPR/Cas9 technology. Our results showed that silencing ApoM suppressed apoptosis and promoted proliferation, migration, invasion and EMT of SMMC7721 cells. The microarray data revealed that a total of 1,868 differentially expressed genes were identified, including VDR. The qRT-PCR and western blot verification results demonstrated that knocking out ApoM could significantly reduce the expression of VDR. The functional recovery experiments indicated that VDR overexpression could offset the inhibition of cell apoptosis and the promotion of cell proliferation, migration, invasion and EMT caused by knocking out ApoM in SMMC7721 cells. Conclusion: ApoM could function as a tumor suppressor to inhibit the growth and metastasis of SMMC7721 cells via VDR signaling in HCC.

Survival of irradiated recipient mice after transplantation of bone marrow from young, old and "early aging" mice

Bone marrow transplantation is used to examine survival, hematopoietic stem cell function and pathology in recipients of young and old wild type bone marrow derived stem cells (BMDSCs) as well as cells from p53-based models of premature aging. There is no difference in the long term survival of recipients of 8 week-old p53+/m donor cells compared to recipients of 8 week-old wild-type (WT) donor cells (70 weeks) or of recipients of 16-18 weeks-old donor cells from either p53+/m or WT mice. There is shorter survival in recipients of older versus younger WT donor bone marrow, but the difference is only significant when comparing 8 and 18 week-old donors. In the p44-based model, short term survival/engraftment is significantly reduced in recipients of 11 month-old p44 donor cells compared to 4 week-old p44 or wild type donor cells of either age; mid-life survival at 40 weeks is also significantly less in recipients of p44 cells. BMDSCs are readily detectable within recipient bone marrow, lymph node, intestinal villi and liver sinusoids, but not in epithelial derived cells. These results indicate that recipients of young BMDSCs may survive longer than recipients of old bone marrow, but the difference is marginal at best.

Bone marrow-derived stem cells and hepatocarcinogenesis in hepatitis B virus transgenic mice

BACKGROUND

Several studies have demonstrated that cancer can develop with the contribution of bone marrow-derived cancer stem cells. We evaluated the possible involvement of bone marrow-derived stem cells in hepatocarcinogenesis in a hepatitis B virus (HBV) transgenic mouse model.

METHODS

Bone marrow cells from wild type male mice were transplanted into sublethally irradiated, female, HBV transgenic mice with hepatocarcinoma nodules. Four months later, liver tissue was examined to localize neoplastic nodules/foci and characterize cells by evaluating the Y-chromosome and the hepatocyte lineage marker hepatocyte nuclear factor-1 (HNF1), as well as the HBsAg encoding gene (HBs-Eg) and HBsAg protein (HBs-Pr) (present only in cells of female origin).

RESULTS

Hepatocytes were HBs-Eg/HBs-Pr-positive in "normal" tissue, while resulted only HBs-Eg-positive in regenerative areas. Neoplastic foci/nodules were both HBs-Eg/HBs-Pr-negative. In the liver, 19 ± 5% of cells were Y-chromosome-positive and about one fifth were HNF1-positive. Y-chromosome and HBs-Eg colocalized in HNF1-positive cells. Y-chromosome-positive cells never localized in neoplastic foci/nodules (HBs-Pr/HBs-Eg-negative).

CONCLUSIONS

Bone marrow-derived stem cells participate in the hepatic regenerative process but not in neoplastic growth. Simultaneous detection of both Y-chromosome and HBs-Eg in the nucleus of an HNF1-positive cell (hepatocyte) demonstrates a phenomenon of cell fusion.

HGF/c-Met signaling mediated mesenchymal stem cell-induced liver recovery in intestinal ischemia reperfusion model

PURPOSE

Liver injury triggered by intestinal ischemia-reperfusion (IIR) usually presage multiorgan dysfunction and death in patients. Recent studies suggest mesenchymal stem cells (MSCs) possess a protective potential against organ damage. Since relative evidence is insufficient and the mechanism is not well understood, we investigated the effect of hepatocyte growth factor c-Met signaling (HGF/c-Met) on recruitment of MSCs and subsequent protection against liver injury triggered by IIR in a rat model.

METHODS

IIR models were built as rats were subjected to 75 min of superior mesenteric artery occlusion and subsequent 4 h reperfusion. Either of pure MSCs and MSCs pretreated with HGF or SU11274 (c-Met inhibitor) were injected into rat models. Biochemical and pathologic alterations of liver in IIR model were measured to evaluate the therapeutic effect of MSCs and drug treatment. Concurrently, the effect of HGF and SU11274 on c-Met and phosphorylated Met expression in MSCs and MSCs migration were assessed in in vitro experiment.

RESULTS

IIR-induced liver injury was manifested by significant increase in serum ALT, AST and HGF levels as well as pathological change. MSCs with highly c-Met expression ameliorated the increase of serum transaminase levels and hepatic histopathological change, while SU11274 weaken these effects. HGF upregulated c-Met and phosphorylated Met expression in MSCs and enhanced its liver protection effect. Transwell assays demonstrated HGF promoted MSCs migration, which was blocked by SU11274.

CONCLUSIONS

HGF/c-Met signaling pathway plays an essential role in the homing of MSCs towards injured liver triggered by intestinal ischemia-reperfusion, and then mediates MSC-induced liver repair.

Recombinant adenovirus carrying the hepatocyte nuclear factor-1alpha gene inhibits hepatocellular carcinoma xenograft growth in mice

Hepatocyte nuclear factor-1alpha (HNF1α) is one of the key transcription factors of the HNF family, which plays a critical role in hepatocyte differentiation. Substantial evidence has suggested that down-regulation of HNF1α may contribute to the development of hepatocellular carcinoma (HCC). Herein, human cancer cells and tumor-associated fibroblasts (TAFs) were isolated from human HCC tissues, respectively. A recombinant adenovirus carrying the HNF1α gene (AdHNF1α) was constructed to determine its effect on HCC in vitro and in vivo. Our results demonstrated that HCC cells and HCC tissues revealed reduced expression of HNF1α. Forced reexpression of HNF1α significantly suppressed the proliferation of HCC cells and TAFs and inhibited the clonogenic growth of hepatoma cells in vitro. In parallel, HNF1α overexpression reestablished the expression of certain liver-specific genes and microRNA 192 and 194 levels, with a resultant increase in p21 levels and induction of G(2)/M arrest. Additionally, AdHNF1α inhibited the expression of cluster of differentiation 133 and epithelial cell adhesion molecule and the signal pathways of the mammalian target of rapamycin and transforming growth factor beta/Smads. Furthermore, HNF1α abolished the tumorigenicity of hepatoma cells in vivo. Most interestingly, intratumoral injection of AdHNF1α significantly inhibited the growth of subcutaneous HCC xenografts in nude mice. Systemic delivery of AdHNF1α could eradicate the orthotopic liver HCC nodules in nonobese diabetic/severe combined immunodeficiency mice.

CONCLUSION

These results suggest that the potent inhibitive effect of HNF1α on HCC is attained by inducing the differentiation of hepatoma cells into mature hepatocytes and G(2)/M arrest. HNF1α might represent a novel, promising therapeutic agent for human HCC treatment. Our findings also encourage the evaluation of differentiation therapy for tumors of organs other than liver using their corresponding differentiation-determining transcription factor.

Treatment of newborn G6pc(-/-) mice with bone marrow-derived myelomonocytes induces liver repair

BACKGROUND & AIMS

Several studies have shown that bone marrow-derived committed myelomonocytic cells can repopulate diseased livers by fusing with host hepatocytes and can restore normal liver function. These data suggest that myelomonocyte transplantation could be a promising approach for targeted and well-tolerated cell therapy aimed at liver regeneration. We sought to determine whether bone marrow-derived myelomonocytic cells could be effective for liver reconstitution in newborn mice knock-out for glucose-6-phosphatase-α.

METHODS

Bone marrow-derived myelomonocytic cells obtained from adult wild type mice were transplanted in newborn knock-out mice. Tissues of control and treated mice were frozen for histochemical analysis, or paraffin-embedded and stained with hematoxylin and eosin for histological examination or analyzed by immunohistochemistry or fluorescent in situ hybridization.

RESULTS

Histological sections of livers of treated knock-out mice revealed areas of regenerating tissue consisting of hepatocytes of normal appearance and partial recovery of normal architecture as early as 1 week after myelomonocytic cells transplant. FISH analysis with X and Y chromosome paints indicated fusion between infused cells and host hepatocytes. Glucose-6-phosphatase activity was detected in treated mice with improved profiles of liver functional parameters.

CONCLUSIONS

Our data indicate that bone marrow-derived myelomonocytic cell transplant may represent an effective way to achieve liver reconstitution of highly degenerated livers in newborn animals.

Continuous cell supply from a Sox9-expressing progenitor zone in adult liver, exocrine pancreas and intestine

The liver and exocrine pancreas share a common structure, with functioning units (hepatic plates and pancreatic acini) connected to the ductal tree. Here we show that Sox9 is expressed throughout the biliary and pancreatic ductal epithelia, which are connected to the intestinal stem-cell zone. Cre-based lineage tracing showed that adult intestinal cells, hepatocytes and pancreatic acinar cells are supplied physiologically from Sox9-expressing progenitors. Combination of lineage analysis and hepatic injury experiments showed involvement of Sox9-positive precursors in liver regeneration. Embryonic pancreatic Sox9-expressing cells differentiate into all types of mature cells, but their capacity for endocrine differentiation diminishes shortly after birth, when endocrine cells detach from the epithelial lining of the ducts and form the islets of Langerhans. We observed a developmental switch in the hepatic progenitor cell type from Sox9-negative to Sox9-positive progenitors as the biliary tree develops. These results suggest interdependence between the structure and homeostasis of endodermal organs, with Sox9 expression being linked to progenitor status.

Recruitment of endogenous bone marrow mesenchymal stem cells towards injured liver

Recent studies suggest that mesenchymal stem cells (MSCs) possess a greater differentiation potential than once thought and that they have the capacity to regenerate damaged tissues/organs. However, the evidence is insufficient, and the mechanism governing the recruitment and homing of MSCs to these injured sites is not well understood. We first examined the MSCs circulating in peripheral blood and then performed chemotaxis, wound healing and tubule-formation assays to investigate the migration capability of mouse bone marrow MSCs (mBM-MSCs) in response to liver-injury signals. In addition, BM-MSCs from donor enhanced green fluorescent protein transgenic male mice were transplanted into liver-injured co-isogenic female recipients, either by intra-bone marrow injection or through the caudal vein, to allow in vivo tracking analysis of the cell fate after transplantation. Donor-derived cells were analysed by in vivo imaging analysis, PCR, flow cytometry and frozen sections. Microarray and real-time PCR were used for chemokine/cytokine and receptor analyses. We successfully isolated circulating MSCs in peripheral blood of liver-injured mice and provided direct evidence that mBM-MSCs could be mobilized into the circulation and recruited into the liver after stimulation of liver injury. CCR9, CXCR4 and c-MET were essential for directing cellular migration towards the injured liver. The recruited mBM-MSCs may play different roles, including hepatic fate specification and down-regulation of the activity of hepatic stellate cells which inhibits over-accumulation of collagen and development of liver fibrosis. Our results provide new insights into liver repair involving endogenous BM-MSCs and add new information for consideration when developing clinical protocols involving the MSCs.

Direct and indirect contribution of bone marrow-derived cells to cancer

Stromal-epithelial interactions may control the growth and initiation of cancers. Here, we not only test the hypothesis that bone marrow-derived cells may effect development of cancers arising from other tissue cells by forming tumor stroma but also that sarcomas may arise by transformation of stem cells from the bone marrow and epithelial cancers may arise by transdifferentiation of bone marrow stem cells to epithelial cancers. Lethally irradiated female FVB/N mice were restored with bone marrow (BM) transplants from a male transgenic mouse carrying the polyoma middle T-oncoprotein under the control of the mouse mammary tumor virus promoter (MMTV-PyMT) and followed for development of lesions. All of 8 lethally irradiated female FVB/N recipient mice, restored with BM transplants from a male MMTV-PyMT transgenic mouse, developed Y-chromosome negative (Y-) cancers of various organs surrounded by Y+ stroma. One of the female FVB/N recipient mice also developed fibrosarcoma and 1, a diploid breast adenocarcinoma containing Y chromosomes. In contrast, only 1 of 12 control female mice restored with normal male BM developed a tumor (lymphoma) during the same time period. These results indicate not only that the transgenic BM-derived stromal cells may indirectly contribute to development of tumors in recipient mice but also that sarcomas may arise by transformation of BM stem cells and that breast cancers arise by transdifferentiation of BM stem cells, presumably by mesenchymal-epithelial transition.

Human progenitor cells with high aldehyde dehydrogenase activity efficiently engraft into damaged liver in a novel model

Human cord blood stem cells (hCBSCs) have been reported to generate hepatocyte-like cells and thus hold promise for repairing damaged liver. However, the frequency of hCBSC-derived hepatocytes varies tremendously between different studies, and it is still controversial as to whether hCBSC-derived cells can transdifferentiate into hepatocytes or simply fuse to recipient hepatocytes. We used the beta-glucuronidase-deficient nonobese diabetic/severe combined immunodeficient/mucopolysaccharidosis type VII (NOD/SCID/MPSVII) mouse model for better identification of engrafted cells. We transplanted lineage-depleted human umbilical cord blood-derived cells with high aldehyde dehydrogenase activity (ALDH(hi)Lin(-)) into irradiated NOD/SCID/MPSVII mice followed by carbon tetrachloride administration to induced liver damage. ALDH(hi)Lin(-) cells were efficiently engrafted in the recipient mouse livers and improved recovery of the mice from toxic insult. The percentage of human cells in these livers ranged between 3% and 14.2% using quantitative real-time polymerase chain reaction. Furthermore, human-originated cells expressing liver-specific alpha1-antitrypsin messenger RNA, albumin and hepatocyte nuclear factor 1 protein were detected in the recipient livers. Interestingly, human versus murine centromeric fluorescent in situ hybridization analysis on the liver sections demonstrated that most human cells were not fused to mouse cells. However, the majority of the human originated albumin-expressing cells also carried mouse genetic material, hence were the product of cell fusion.

CONCLUSION

hCBSCs or their progeny may home to the injured liver and release trophic factors that hasten tissue repair, whereas fusion of these cells with hepatocytes may occur rarely and contribute to a lesser extent to liver repair.

Bone marrow-derived lung epithelial cells

Bone marrow-derived cells can take on the phenotype of epithelial cells and express epithelial-specific genes in multiple organs. Here, we focus on recent data on the appearance of marrow-derived epithelial cells in the adult lung. These findings have garnered significant skepticism because in most cases marrow-derived epithelial cells are very rare, the marrow cell of origin is not known, the techniques for detection have needed improvement, and there seem to be multiple mechanisms by which this occurs. Recent studies have focused on these concerns. Once these important concerns are addressed, further studies on the function(s) of these cells will need to be performed to determine whether this engraftment has any clinical significance-either beneficial or detrimental.

Alpha-fetoprotein, stem cells and cancer: how study of the production of alpha-fetoprotein during chemical hepatocarcinogenesis led to reaffirmation of the stem cell theory of cancer

Identification of the cells in the liver that produce alpha-fetoprotein during development, in response to liver injury and during the early stages of chemical hepatocarcinogenesis led to the conclusion that maturation arrest of liver-determined tissue stem cells was the cellular process that gives rise to hepatocellular carcinomas. When the cellular changes in these processes were compared to that of the formation of teratocarcinomas, the hypothesis arose that all cancers arise from maturation arrest of tissue-determined stem cells. This was essentially a reinterpretation of the embryonal rest theory of cancer whereby tissue stem cells take the role of embryonal rests. A corollary of the stem cell theory of the origin of cancer is that cancers contain the same functional cell populations as normal tissues: stem cells, transit-amplifying cells and mature cells. Cancer stem cells retain the essential feature of normal stem cells: the ability to self-renew. Growth of cancers is due to continued proliferation of cancer transit-amplifying cells that do not differentiate to mature cells (maturation arrest). On the other hand, cancer stem cells generally divide very rarely and contribute little to tumor growth. However, the presence of cancer stem cells in tumors is believed to be responsible for the properties of immortalization, transplantability and resistance to therapy characteristic of cancers. Current therapies for cancer (chemotherapy, radiotherapy, antiangiogenesis and differentiation therapy) are directed against the cancer transit-amplifying cells. When these therapies are discontinued, the cancer reforms from the cancer stem cells. Therapy directed toward interruption of the cell signaling pathways that maintain cancer stem cells could lead to new modalities to the prevention of regrowth of the cancer.