Insulin-like growth factor II in hepatocellular carcinoma

Splenic serum from portal hypertensive patients enhances liver stem cell proliferation and self-renewal via the IGF-II/ERK signaling pathway

BACKGROUND

Hypersplenism is a serious complication of portal hypertension (PH) and can affect the prognosis of liver disease. Liver stem cells (LSCs) are involved in liver regeneration and hepatocarcinogenesis after liver cirrhosis.

AIM

To explore the effects and mechanism of the spleen on the proliferation and differentiation of LSCs in PH due to liver cirrhosis.

METHODS

Fetal liver stem cells (FLSCs) were treated with splenic serum from liver cirrhosis patients with hypersplenism and control serum from healthy volunteers, and the proliferation, self-renewal, and IGF-II/ERK signaling pathway of FLSCs were then evaluated.

RESULTS

We found that splenic serum from PH patients promoted FLSC proliferation, colony formation, and Ki-67 expression in vitro. Splenic serum from PH also enhanced FLSC spheroid formation in vitro. Mechanistically, we determined that insulin-like growth factor (IGF)-II concentration was elevated in splenic serum from PH patients and could promote FLSC proliferation and self-renewal. Furthermore, both IGF-II and splenic serum from PH patients enhanced ERK signaling activation through IGF-I receptor (IGF-I R) in FLSCs. Consistently, blocking IGF-I R or ERK signaling could attenuate the effects of splenic serum from PH patients on FLSCs.

CONCLUSIONS

The spleen in PH patients promotes FLSC proliferation and self-renewal through the IGF-II/ERK signaling pathway.

Non-islet-cell tumour hypoglycaemia in a cat with hepatocellular carcinoma

Case summary

An 11-year-old male neutered domestic shorthair cat presented with behavioural changes. Physical examination revealed bradycardia and a cranial abdominal mass. The cat was persistently hypoglycaemic (1.2 mmol/l; reference interval [RI] 3.5–5.5 mmol/l) with decreased fructosamine concentration suggesting chronic hypoglycaemia, and decreased insulin concentration excluding insulinoma. Alanine aminotransferase activity was markedly increased (1219.31 U/l; RI 15–60 U/l). On staging CT a large, multilobulated hepatic mass was identified, with no evidence of metastatic disease. After surgical removal serum glucose concentration and heart rate quickly returned to within the RIs. Histopathology was consistent with a solid-to-trabecular, well-differentiated, hepatocellular carcinoma. There was no recurrence of signs or mass during 8 months of follow-up, and the cat was still alive 20 months after surgery.

Relevance and novel information

Non-islet-cell tumour hypoglycaemia (NICTH) is a rare but life-threatening paraneoplastic syndrome. In humans, hepatocellular carcinoma is the most common epithelial tumour causing NICTH, but these are uncommon in cats, and associated paraneoplastic hypoglycaemia has not been reported. Possible mechanisms include aberrant secretion of big insulin growth factor 2; however, this could not be confirmed. NICTH should be considered in the differential diagnosis of cats with persistent hypoglycaemia.

A hypothesis on paradoxical privileged portal vein metastasis of hepatocellular carcinoma. Can organ evolution shed light on patterns of human pathology, and vice versa?

Unlike other carcinomas, hepatocellular carcinoma (HCC) metastasizes to distant organs relatively rarely. In contrast, it routinely metastasizes to liver vasculature/liver, affecting portal veins 3-10 times more often than hepatic veins. This portal metastatic predominance is traditionally rationalized within the model of a reverse portal flow, due to accompanying liver cirrhosis. However, this intuitive model is not coherent with facts: 1) reverse portal flow occurs in fewer than 10% of cirrhotic patients, while portal metastasis occurs in 30-100% of HCC cases, and 2) portal vein prevalence of HCC metastasis is also characteristic of HCC in non-cirrhotic livers. Therefore, we must assume that the route for HCC metastatic dissemination is the same as for other carcinomas: systemic dissemination via the draining vessel, i.e., via the hepatic vein. In this light, portal prevalence versus hepatic vein of HCC metastasis appears as a puzzling pattern, particularly in cases when portal HCC metastases have appeared as the sole manifestation of HCC. Considering that other GI carcinomas (colorectal, pancreatic, gastric and small bowel) invariably disseminate via portal vein, but very rarely form portal metastasis, portal prevalence of HCC metastasis appears as a paradox. However, nature does not contradict itself; it is rather our wrong assumptions that create paradoxes. The 'portal paradox' becomes a logical event within the hypothesis that the formation of the unique portal venous system preceded the appearance of liver in evolution of chordates. The analysis suggests that the appearance of the portal venous system, supplying hormones and growth factors of pancreatic family, which includes insulin, glucagon, somatostatin, and pancreatic polypeptide (HGFPF) to midgut diverticulum in the early evolution of chordates (in an Amphioxus-like ancestral animal), promoted differentiation of enterocytes into hepatocytes and their further evolution to the liver of vertebrates. These promotional-dependent interactions are conserved in the vertebrate lineage. I hypothesize that selective homing and proliferation of malignant hepatocytes (i.e., HCC cells) in the portal vein environment are due to a uniquely high concentration of HGFPF in portal blood. HGFPF are also necessary for liver function and renewal and are significantly extracted by hepatocytes from passing blood, creating a concentration gradient of HGFPF between the portal blood and hepatic vein outflow, making post-liver vasculature and remote organs less favorable spaces for HCC growth. It also suggested that the portal vein environment (i.e., HGFPF) promotes the differentiation of more aggressive HCC clones from already-seeded portal metastases, explaining the worse outcome of HCC with the portal metastatic pattern. The analysis also offers new hypothesis on the phylogenetic origin of the hepatic diverticulum of cephalochordates, with certain implications for the modeling of the chordate phylogeny.

Privileged portal metastasis of hepatocellular carcinoma in light of the coevolution of a visceral portal system and liver in the chordate lineage: a search for therapeutic targets

Hepatocellular carcinoma (HCC) disseminates systemically, but metastases occur in distant organs only in minority of patients, whereas HCC routinely metastasizes to liver and its vessels. HCC cells disseminate via hepatic veins, but portal veins are affected by metastasis more frequently than are hepatic veins, and correlates with poor prognosis. In this review, I suggest that privileged HCC portal metastasis occurs because of high levels of pancreatic family hormones and growth factors (PHGFs) in the portal blood. The analysis suggests that the appearance of the portal system carrying PHGFs in the evolution of invertebrate chordate (Amphioxus) led to the evolution of the liver in vertebrate; given that the portal pattern of HCC metastasis and selection of more-aggressive clones are PHGF dependent, PHGFs and their ligands constitute therapeutic targets.

Urinary transforming growth factor α and serum α-fetoprotein as tumor markers of hepatocellular carcinoma

This case-control study aimed to evaluate the diagnostic application of urinary transforming growth factor (TGF) α and serum α-fetoprotein (AFP) in hepatocellular carcinoma (HCC). TGFα and AFP were determined in 90 pairs of age- and gender-matched patients with cirrhotic HCC and patients with cirrhosis alone and 60 healthy controls. The results indicated that TGFα and AFP levels in patients with HCC were higher than in those with cirrhosis alone or healthy controls (each P = 0.0001). Multivariate analysis indicated that TGFα (odds ratio (OR) 1.03, 95% confidence interval (CI) 1.05-1.16) and AFP (OR 1.03, 95% CI 1.01-1.06) were closely associated, in a dose-related fashion, with the development of HCC. The optimal cutoff values, determined with the receiver operating characteristic (ROC) curves, were 29 μg/g creatinine for TGFα and 100 ng/ml for AFP, respectively. The areas under ROC curve (AUC) were 0.74 for TGFα and 0.78 for AFP, respectively. Both biomarkers showed the same sensitivity (52.2%), high specificity, high positive predictive value, and moderate positive likelihood ratio. Determination of both markers in parallel significantly increased the AUC (0.91) and diagnostic accuracy (92.2%), with a high sensitivity (86.7 %), specificity (97.8%), positive predictive value (PPV; 97.5%), and moderate positive likelihood ratio (PLR; 39.4). Among 31 cirrhotic HCC with AFP ≤ 20 ng/ml, the calculated AUC for TGFα was 0.79, with a sensitivity of 64.5%, specificity of 96.7%, PPV of 87.0%, and PLR of 19.5. In conclusion, urinary TGFα and serum AFP are complementary tumor markers for detection of HCC with low AFP production.