Thyroid hormone in the regulation of hepatocellular carcinoma and its microenvironment

Hepatocellular carcinoma (HCC) commonly arises from a liver damaged by extensive inflammation and fibrosis. Various factors including cytokines, morphogens, and growth factors are involved in the crosstalk between HCC cells and the stromal microenvironment. Increasing our understanding of how stromal components interact with HCC and the signaling pathways involved could help identify new therapeutic and/or chemopreventive targets. It has become increasingly clear that the cross-talk between tumor cells and host stroma plays a key role in modulating tumor growth. Emerging reports suggest a relationship between HCC and thyroid hormone signaling (dysfunction), raising the possibility that perturbed thyroid hormone (TH) regulation influences the cancer microenvironment and cancer phenotype. This review provides an overview of the role of thyroid hormone and its related pathways in HCC and, specifically, its role in regulating the tumor microenvironment.

Hedgehog regulates yes-associated protein 1 in regenerating mouse liver

Adult liver regeneration requires induction and suppression of proliferative activity in multiple types of liver cells. The mechanisms that orchestrate the global changes in gene expression that are required for proliferative activity to change within individual liver cells, and that coordinate proliferative activity among different types of liver cells, are not well understood. Morphogenic signaling pathways that are active during fetal development, including Hedgehog and Hippo/Yes-associated protein 1 (Yap1), regulate liver regeneration in adulthood. Cirrhosis and liver cancer result when these pathways become dysregulated, but relatively little is known about the mechanisms that coordinate and control morphogenic signaling during effective liver regeneration. We evaluated the hypothesis that the Hedgehog pathway controls Yap1 activation during liver regeneration by studying intact mice and cultured liver cells. In cultured hepatic stellate cells (HSCs), disrupting Hedgehog signaling blocked activation of Yap1, and knocking down Yap1 inhibited induction of both Yap1- and Hedgehog-regulated genes that enable HSC to become myofibroblasts (MFs). In mice, disrupting Hedgehog signaling in MFs inhibited liver regeneration after partial hepactectomy (PH). Reduced proliferative activity in the liver epithelial compartment resulted from loss of stroma-derived paracrine signals that activate Yap1 and the Hedgehog pathway in hepatocytes. This prevented hepatocytes from up-regulating Yap1- and Hedgehog-regulated transcription factors that normally promote their proliferation.

CONCLUSIONS

Morphogenic signaling in HSCs is necessary to reprogram hepatocytes to regenerate the liver epithelial compartment post-PH. This discovery identifies novel molecules that might be targeted to correct defective repair during cirrhosis and liver cancer. (Hepatology 2016;64:232-244).

Practical approach to non-alcoholic fatty liver disease in patients with diabetes

The prevalence of Type 2 diabetes is expected to increase in parallel with obesity rates and the ageing population. Recent studies show that Type 2 diabetes is associated with a twofold increase in the risk of non-alcoholic fatty liver disease, a leading cause of chronic liver disease. Individuals with non-alcoholic steatohepatitis, a more advanced stage of non-alcoholic fatty liver disease, are specifically at risk of developing fibrosis/cirrhosis (end-stage liver disease) and hepatocellular carcinoma; therefore, identifying individuals (with Type 2 diabetes) who are likely to develop hepatic complications is paramount. In the present clinical review, we discuss the potential impact of non-alcoholic fatty liver disease diagnosis on Type 2 diabetes, and the putative risk factors for developing non-alcoholic steatohepatitis and non-alcoholic steatohepatitis fibrosis. We highlight the limitations of currently used tools in non-alcoholic fatty liver disease diagnosis and staging, and provide an insight into future developments in the field. We present an example of a non-alcoholic fatty liver disease screening protocol and discuss the therapeutic options currently available to our patients.

Osteopontin neutralisation abrogates the liver progenitor cell response and fibrogenesis in mice

BACKGROUND

Chronic liver injury triggers a progenitor cell repair response, and liver fibrosis occurs when repair becomes deregulated. Previously, we reported that reactivation of the hedgehog pathway promotes fibrogenic liver repair. Osteopontin (OPN) is a hedgehog-target, and a cytokine that is highly upregulated in fibrotic tissues, and regulates stem-cell fate. Thus, we hypothesised that OPN may modulate liver progenitor cell response, and thereby, modulate fibrotic outcomes. We further evaluated the impact of OPN-neutralisation on murine liver fibrosis.

METHODS

Liver progenitors (603B and bipotential mouse oval liver) were treated with OPN-neutralising aptamers in the presence or absence of transforming growth factor (TGF)-β, to determine if (and how) OPN modulates liver progenitor function. Effects of OPN-neutralisation (using OPN-aptamers or OPN-neutralising antibodies) on liver progenitor cell response and fibrogenesis were assessed in three models of liver fibrosis (carbon tetrachloride, methionine-choline deficient diet, 3,5,-diethoxycarbonyl-1,4-dihydrocollidine diet) by quantitative real time (qRT) PCR, Sirius-Red staining, hydroxyproline assay, and semiquantitative double-immunohistochemistry. Finally, OPN expression and liver progenitor response were corroborated in liver tissues obtained from patients with chronic liver disease.

RESULTS

OPN is overexpressed by liver progenitors in humans and mice. In cultured progenitors, OPN enhances viability and wound healing by modulating TGF-β signalling. In vivo, OPN-neutralisation attenuates the liver progenitor cell response, reverses epithelial-mesenchymal-transition in Sox9+ cells, and abrogates liver fibrogenesis.

CONCLUSIONS

OPN upregulation during liver injury is a conserved repair response, and influences liver progenitor cell function. OPN-neutralisation abrogates the liver progenitor cell response and fibrogenesis in mouse models of liver fibrosis.

Osteopontin mediates an MZF1-TGF-β1-dependent transformation of mesenchymal stem cells into cancer-associated fibroblasts in breast cancer

Interactions between tumor cells and cancer-associated fibroblasts (CAFs) in the tumor microenvironment (TMEN) significantly influence cancer growth and metastasis. Transforming growth factor-β (TGF-β) is known to be a critical mediator of the CAF phenotype, and osteopontin (OPN) expression in tumors is associated with more aggressive phenotypes and poor patient outcomes. The potential link between these two pathways has not been previously addressed. Utilizing in vitro studies using human mesenchymal stem cells (MSCs) and MDA-MB231 (OPN+) and MCF7 (OPN−) human breast cancer cell lines, we demonstrate that OPN induces integrin-dependent MSC expression of TGF-β1 to mediate adoption of the CAF phenotype. This OPN-TGF-β1 pathway requires the transcription factor, myeloid zinc finger 1 (MZF1). In vivo studies with xenotransplant models in NOD-scid mice showed that OPN expression increases cancer growth and metastasis by mediating MSC-to-CAF transformation in a process that is MZF1- and TGF-β1-dependent. We conclude that tumor-derived OPN engenders MSC-to-CAF transformation in the microenvironment to promote tumor growth and metastasis via the OPN-MZF1-TGF-β1 pathway.

Myofibroblastic cells function as progenitors to regenerate murine livers after partial hepatectomy

OBJECTIVE

Smoothened (SMO), a coreceptor of the Hedgehog (Hh) pathway, promotes fibrogenic repair of chronic liver injury. We investigated the roles of SMO+ myofibroblast (MF) in liver regeneration by conditional deletion of SMO in α smooth muscle actin (αSMA)+ cells after partial hepatectomy (PH).

DESIGN

αSMA-Cre-ER(T2)×SMO/flox mice were treated with vehicle (VEH) or tamoxifen (TMX), and sacrificed 24-96 h post-PH. Regenerating livers were analysed for proliferation, progenitors and fibrosis by qRT-PCR and quantitative immunohistochemistry (IHC). Results were normalised to liver segments resected at PH. For lineage-tracing studies, αSMA-Cre-ER(T2)×ROSA-Stop-flox-yellow fluorescent protein (YFP) mice were treated with VEH or TMX; livers were stained for YFP, and hepatocytes isolated 48 and 72 h post-PH were analysed for YFP by flow cytometric analysis (FACS).

RESULTS

Post-PH, VEH-αSMA-SMO mice increased expression of Hh-genes, transiently accumulated MF, fibrosis and liver progenitors, and ultimately exhibited proliferation of hepatocytes and cholangiocytes. In contrast, TMX-αSMA-SMO mice showed loss of whole liver SMO expression, repression of Hh-genes, enhanced accumulation of quiescent HSC but reduced accumulation of MF, fibrosis and progenitors, as well as inhibition of hepatocyte and cholangiocyte proliferation, and reduced recovery of liver weight. In TMX-αSMA-YFP mice, many progenitors, cholangiocytes and up to 25% of hepatocytes were YFP+ by 48-72 h after PH, indicating that liver epithelial cells were derived from αSMA-YFP+ cells.

CONCLUSIONS

Hh signalling promotes transition of quiescent hepatic stellate cells to fibrogenic MF, some of which become progenitors that regenerate the liver epithelial compartment after PH. Hence, scarring is a component of successful liver regeneration.

Familial idiopathic pulmonary fibrosis in association with bone marrow hypoplasia and hepatic nodular regenerative hyperplasia: a new "trimorphic" syndrome

This is the first report of familial idiopathic pulmonary fibrosis associated with hepatic nodular regenerative hyperplasia and bone marrow hypoplasia. Four members of one family presented with this triad of organ dysfunction. The response to immunosuppressive treatment was poor and all four members succumbed to the disease processes. The current literature is reviewed and mechanisms that could have been involved in the development of this new syndrome are proposed.

Haematological malignancies presenting with acute liver injury: a single-centre experience

INTRODUCTION

Early recognition and identification of the underlying cause of acute liver injury (ALI) is crucial in instituting medical treatment and assessing the need for liver transplantation. Haematological malignancies have been reported to present as ALI with progression to acute liver failure but experience is limited.

AIM

Review our experience of ALI secondary to haematological malignancies.

PATIENTS AND METHODS

Patients admitted to the liver unit with ALI secondary to a haematological malignancy between 1996 and 2006 were identified. A retrospective review was made of their case notes and our database.

RESULTS

Of the 752 cases of ALI, six cases of ALI secondary to haematological malignancy were identified. Common features were a prodromal illness (median duration of 5 weeks; range 2-6 weeks) and jaundice (median bilirubin 208 micromol/l; range 112-238 micromol/l). The majority of patients (5/6) had hepatomegaly. Liver biopsy was performed in two patients and confirmed the diagnosis in both cases. In other cases, the diagnosis was made following lymph node biopsy (1), bone marrow examination (2) or from post-mortem examination (1). Median time from jaundice to encephalopathy was 12 days; range 1-22 days. A single patient underwent liver transplantation but died in the immediate post-operative period. All patients died soon after admission with a median survival of 8 days (range 3-26 days).

CONCLUSION

Haematological malignancy should be considered in ALI patients presenting with a prodromal illness, jaundice and hepatomegaly. Biopsy is essential to confirm the diagnosis but the benefit of definitive therapy such as chemotherapy and/or transplantation in this setting is unclear and survival is poor.

Comparison of maternal ghrelin and leptin in healthy mothers and mothers with Type 1 diabetes

AIMS

Maternal leptin affects placental growth hormone (GH), whereas ghrelin, a natural ligand of the growth-hormone-secretagogue receptor, modulates GH action. Both hormones may affect fetal growth, and dysregulation in diabetes may lead to fetal growth disturbances. The aim was to investigate changes in maternal ghrelin during pregnancy with diabetes and to establish reference leptin levels.

METHODS

Twelve healthy non-diabetic (ND) and 12 pregnant women with Type 1 diabetes (T1DM) were recruited. Age and body mass index (BMI) [ND: age 29.9 +/- 4.7 years (mean +/- sd), BMI 25.2 +/- 3.7 kg/m2; T1DM: age 31 +/- 5.5 years, BMI 27 +/- 3.1 kg/m2] were similar in the groups. HbA1c in T1DM was 6.2 +/- 1.1% at 20 weeks, 6.3 +/- 1.1% at 30 weeks' gestation and 7.8 +/- 2.1% postpartum. Fasting plasma ghrelin, total leptin, free leptin (FL) and soluble leptin receptor (sOB-R) levels were measured at 20 and 30 weeks' gestation and postpartum and determined by radioimmunoassay.

RESULTS

All pregnancies resulted in full-term singleton births with no differences in birth weight between groups [T1DM: 3.4 +/- 0.56 kg (mean +/- SE); ND: 3.6 +/- 0.3 kg, P = NS]. Ghrelin levels were lower in T1DM when corrected for age and mothers' weight (T1DM: 458 +/- 36 pg/ml and 432.9 +/- 26.6 pg/ml; ND: 562 +/- 52 pg/ml and 515.8 +/- 63 pg/ml at 20 and 30 weeks, respectively, P < 0.05). T1DM mothers had higher levels of sOB-R and FL levels declined at 30 weeks' gestation in T1DM (P = 0.04) but not in ND.

CONCLUSION

In a population of pregnant women with expected changes in leptin levels as previously reported, ghrelin levels were lower in T1DM pregnancies at 20 and 30 weeks. This may have implications for fetal development and requires further study in diabetes, particularly in pregnancies that result in macrosomia.

Ciprofloxacin suppresses bacterial overgrowth, increases fasting insulin but does not correct low acylated ghrelin concentration in non-alcoholic steatohepatitis

BACKGROUND

Insulin resistance and oxidative stress induced by products of small intestinal bacterial activity are putative factors in the pathogenesis of non-alcoholic steatohepatitis. Acylated ghrelin is the biologically active form of an orexigenic gastric hormone that modifies insulin sensitivity and body composition.

AIM

To investigate the effect of ciprofloxacin on small intestinal bacterial activity, ethanol, ghrelin and insulin in non-alcoholic steatohepatitis patients.

METHODS

Twelve non-alcoholic steatohepatitis patients and 11 controls were studied before and after ciprofloxacin 500 mg b.d. for 5 days. After an overnight fast, 75 g glucose was ingested and blood was sampled every 20 min for 120 min. Acylated and total ghrelin, ethanol and insulin were measured. Small intestinal bacterial activity was detected by glucose hydrogen breath test.

RESULTS

Mean (range) integrated plasma acylated ghrelin which was 102 (21-241) and 202 (88-366) pg/mL . 2 h in non-alcoholic steatohepatitis and controls respectively (P = 0.015). This difference persisted after correction for body mass index and was unaffected by ciprofloxacin treatment. One of six non-alcoholic steatohepatitis patients positive for small intestinal bacterial activity remained positive after ciprofloxacin. In contrast, the one healthy control positive for small intestinal bacterial activity remained positive after ciprofloxacin (P = 0.025). Ethanol was detected in two subjects in each group, becoming immeasurable after ciprofloxacin. In non-alcoholic steatohepatitis patients median (range) fasting insulin increased from 113 (10-223) to 152 (32-396) pmol/L (P < 0.02), after ciprofloxacin. This was accompanied by similar changes in insulin resistance.

CONCLUSIONS

Small intestinal bacterial activity is common in non-alcoholic steatohepatitis. Low acylated ghrelin in non-alcoholic steatohepatitis cannot be attributed to small intestinal bacterial activity. Changes in fasting insulin and ethanol following ciprofloxacin suggest that these parameters may be influenced by small intestinal bacterial activity.

Carbamazepine-induced acute liver failure as part of the DRESS syndrome

Carbamazepine is a widely used drug. It is commonly associated with hepatic abnormalities, ranging from an asymptomatic rise in liver function tests to acute liver failure. The most severe reaction occurs as part of a generalised hypersensitivity reaction, also known as drug reaction, eosinophilia and systemic symptoms (DRESS). We describe a case of a young adult who presented with non-specific symptoms, which progressed to fulminant hepatic failure, displaying the hallmarks of DRESS. We highlight the need for awareness of such an association.

Genetic haemochromatosis presenting as porphyria cutanea tarda

Porphyria cutanea tarda (PCT) is the commonest form of porphyria. It can be inherited or acquired. We present a case of genetic haemochromatosis with associated PCT. Venesection led to improvement in both conditions. We highlight the need for the awareness of PCT and its associated conditions.

Esophageal involvement in cicatricial pemphigoid: a rare cause of dysphagia

Cicatricial pemphigoid is a rare, autoimmune, blistering disorder affecting the mucous membranes and skin. Esophageal involvement affects a small proportion of affected individuals and may present up to 10 years after the initial onset of the disease. We present a case of esophageal cicatricial pemphigoid that presented initially as linear IgA disease. We describe the successful treatment of dysphagia by graded esophageal dilatations.

Lack of association between thyroid and adrenal nodules: a histological study

The prevalence of thyroid nodules is increased in patients with Cushing's disease, but the possibility of an association between thyroid and adrenal nodules in other patient groups has not been formally tested. We have evaluated the co-existence of thyroid and adrenal nodules in retrospective and prospective autopsy studies. Retrospective (83 autopsies) and prospective (29 autopsies) blinded studies of thyroid and adrenal gland histopathology were performed by two experienced histopathologists in unselected autopsies. The presence of nodules, defined as areas of tissue having discrete edges within the gland parenchyma seen as a step difference between the cells or architecture adjacent to the nodule, was determined for each gland. No association was found between the presence of adrenal and thyroid nodules in either the retrospective or prospective studies (p>0.2 for both). In the retrospective study, 23% of specimens had thyroid nodules and 28% adrenal nodules. In the prospective study, 24% of specimens had thyroid nodules and 7% adrenal nodules. The proportion of patients with adrenal nodules in the prospective study was significantly less than that in the retrospective study. In conclusion, thyroid and adrenal nodules are frequent autopsy findings in the general population but we have found no evidence of a relationship between the occurrence of nodules in these glands.