Relation of serum insulin-like growth factor-1 (IGF-1) levels with hepatitis C virus infection and insulin resistance

Growth Hormone Signaling in Liver Diseases: Therapeutic Potentials and Controversies

Growth hormone (GH) and downstream insulin-like growth factor 1 (IGF1) signaling mediate growth and metabolism. GH deficiency causes short stature or dwarfism, and excess GH causes acromegaly. Although the association of GH/IGF1 signaling with liver diseases has been suggested previously, current studies are controversial and the functional roles of GH/IGF1 signaling are still undefined. GH supplementation therapy showed promising therapeutic effects in some patients, such as non-alcoholic fatty liver disease, but inhibition of GH signaling may be beneficial for other liver diseases, such as hepatocellular carcinoma. The functional roles of GH/IGF1 signaling and the effects of agonists/antagonists targeting this signaling may differ depending on the liver injury or animal models. This review summarizes current controversial studies of GH/IGF1 signaling in liver diseases and discusses therapeutic potentials of GH therapy.

Circulating Insulin-like Growth Factor-I Concentrations and Risk of 30 Cancers: Prospective Analyses in UK Biobank

Circulating insulin-like growth factor I (IGF-I) is positively associated with the risks of colorectal, breast, and prostate cancer, but evidence for other less common cancers is limited. In this study, we investigated associations between serum IGF-I concentrations and incidence of less common cancers in the UK Biobank study. To enable comparison of effect estimates, and as positive controls, both common and less common cancer sites (total 30) were included in an outcome-wide analysis. Data from 394,388 cancer-free participants in the UK Biobank study were analyzed. Multivariable adjusted Cox proportional hazards models were used to determine associations between baseline serum IGF-I concentrations and cancer incidence, using repeated IGF-I measurements from up to 14,149 participants to correct for regression dilution bias. Higher IGF-I concentration was associated with increased risks of thyroid cancer [HR per 5 nmol/L higher concentration 1.18; 95% confidence interval (CI), 1.01-1.37] in addition to colorectal (HR, 1.08; 95% CI, 1.03-1.13), breast (HR, 1.11; 95% CI, 1.07-1.15), and prostate cancer (HR, 1.08; 95% CI, 1.05-1.12), and reduced risks of ovarian and liver cancer. Mean follow-up was 6.9 years and the possibility that the observed associations may be influenced by reverse causality bias cannot be excluded. Additional nominally significant associations with malignant melanoma, multiple myeloma, oral cancer, and esophageal squamous cell carcinoma did not survive correction for multiple testing. Studies with longer follow-up and pooled analyses are needed to further assess how broad the role of IGF-I is in cancer development. SIGNIFICANCE: The results from this outcome-wide analysis are consistent with a positive association of IGF-I with cancers at several sites.

Study on the relationship between insulin growth factor 1 and liver fibrosis in patients with chronic hepatitis C with type 2 diabetes mellitus

OBJECTIVE

To investigate the correlation between serum protein level of insulin growth factor 1 (IGF-1) and the degree of liver fibrosis in patients with chronic hepatitis C (CHC) combined with type 2 diabetes mellitus (T2DM).

METHODS

The cases are divided into four groups. Then serum levels of IFG-1, alanine aminotransferase (ALT), aspartate aminotransferase (AST), hepatitis C virus (HCV) RNA, and HCV genotypes were detected simultaneously in patients with hepatitis C, liver stiffness measurement (LSM) was measured by transient elastography, and aspartate aminotransferase platelet ratio (APRI) score was determined.

RESULTS

There was no significant difference between CHC with T2DM group and CHC group in diabetes family history (P > 0.05), but the difference between the two groups were significantly lower than that of T2DM group ( P < 0.05). The levels of fasting insulin and homeostatic model assessment of insulin resistance (HOMA-IR) in CHC group with T2DM group were significantly higher than those in the other two groups ( P < 0.05), while the IGF-1 RNA and the serum protein level in the two groups were significantly lower than those in the CHC group, and were lower than those in the control group ( P < 0.05). The level of serum IGF-1 was negatively correlated with HOMA-IR, LSM, and APRI score in CHC with T2DM group ( r = -0.71, -0.75, and -0.69; P < 0.01).

CONCLUSION

The degree of hepatic fibrosis in patients with CHC combined with T2DM was higher than that in non-T2DM patients with CHC, which was mainly related to insulin resistance (IR) induced by 1b genotype HCV infection. IR can lead to impaired synthesis of IGF-1, and the degree of damage has a corresponding relationship with hepatic fibrosis.

Tryptophan-kynurenine metabolism and insulin resistance in hepatitis C patients

Chronic hepatitis C virus (HCV) infection is associated with 50% incidence of insulin resistance (IR) that is fourfold higher than that in non-HCV population. IR impairs the outcome of antiviral treatment. The molecular mechanisms of IR in HCV are not entirely clear. Experimental and clinical data suggested that hepatitis C virus per se is diabetogenic. However, presence of HCV alone does not affect IR. It was proposed that IR is mediated by proinflammatory cytokines, mainly by TNF-alpha. TNF-alpha potentiates interferon-gamma-induced transcriptional activation of indoleamine 2,3-dioxygenase, the rate-limiting enzyme of tryptophan- (TRP-) kynurenine (KYN) metabolism. Upregulation of TRP-KYN metabolism was reported in HCV patients. KYN and some of its derivatives affect insulin signaling pathways. We hypothesized that upregulation of TRP-KYN metabolism might contribute to the development of IR in HCV. To check this suggestion, we evaluated serum concentrations of TRP and KYN and HOMA-IR and HOMA-beta in 60 chronic HCV patients considered for the treatment with IFN-alpha. KYN and TRP concentrations correlated with HOMA-IR and HOMA-beta scores. Our data suggest the involvement of KYN and its metabolites in the development of IR in HCV patients. TRP-KYN metabolism might be a new target for prevention and treatment of IR in HCV patients.

Insulin resistance and cancer: the role of insulin and IGFs

Insulin, IGF1, and IGF2 are the most studied insulin-like peptides (ILPs). These are evolutionary conserved factors well known as key regulators of energy metabolism and growth, with crucial roles in insulin resistance-related metabolic disorders such as obesity, diseases like type 2 diabetes mellitus, as well as associated immune deregulations. A growing body of evidence suggests that insulin and IGF1 receptors mediate their effects on regulating cell proliferation, differentiation, apoptosis, glucose transport, and energy metabolism by signaling downstream through insulin receptor substrate molecules and thus play a pivotal role in cell fate determination. Despite the emerging evidence from epidemiological studies on the possible relationship between insulin resistance and cancer, our understanding on the cellular and molecular mechanisms that might account for this relationship remains incompletely understood. The involvement of IGFs in carcinogenesis is attributed to their role in linking high energy intake, increased cell proliferation, and suppression of apoptosis to cancer risks, which has been proposed as the key mechanism bridging insulin resistance and cancer. The present review summarizes and discusses evidence highlighting recent advances in our understanding on the role of ILPs as the link between insulin resistance and cancer and between immune deregulation and cancer in obesity, as well as those areas where there remains a paucity of data. It is anticipated that issues discussed in this paper will also recover new therapeutic targets that can assist in diagnostic screening and novel approaches to controlling tumor development.

Cancer cachexia and anabolic interventions: a case report

BACKGROUND

Standard-of-care (SOC) cancer treatments are primarily aimed at reducing size and progression of a tumor. There is a need for successful supplemental anabolic therapies to combat cancer cachexia in addition to these SOC treatment modalities. Anabolic interventions, including testosterone and amino acid supplements, may be beneficial in reducing and/or reversing muscle wasting in these patient populations.

METHODS

A 48-year-old Caucasian female with recurrent cervical cancer was scheduled to receive three 21-day cycles of cisplatin and topetecan chemotherapy. She qualified, consented, and enrolled into a blinded interventional pilot study where she received daily whey protein (10 g, three times per day with meals) and a weekly injection of testosterone enanthate (100 mg intramuscular) before and during the SOC chemotherapy treatment period. Body composition, serum inflammatory markers, mixed muscle protein synthesis and breakdown rates, physical function, fatigue, and quality of life were assessed before and after the intervention period.

RESULTS

Body composition, as assessed by an increase in body weight and lean body mass and reduction in fat mass; physical function; fatigue; and quality of life each improved across the entire intervention period despite general increases in inflammatory markers and no improvements in muscle protein turnover towards the end of the intervention.

CONCLUSIONS

Concomitant treatment of oral amino acids and testosterone may be a viable therapeutic option for fighting cachexia and improving body composition and quality of life during chemotherapeutic treatment of recurrent cervical cancer. These positive outcomes may be attainable over time despite overall poor inflammatory status.

The insulin-like growth factor (IGF) signaling axis and hepatitis C virus-associated carcinogenesis (review)

Insulin-like growth factor (IGF) signaling plays an important autocrine, paracrine and endocrine role in growth promotion involving various tissues and organs. Synthesis of both IGFs (IGF-1 and IGF-2) in normal conditions takes place mainly in the liver even if the proteins can be produced in every cell of the human body. The alterations in the IGF signaling axis in human hepatocarcinogenesis are described, but mechanisms of the interactions between expression of oncogenic hepatitis C virus (HCV) proteins and components of the IGF system in progression of chronic hepatitis C to primary hepatocellular carcinoma (HCC) have been poorly recognised. In advanced stages of liver diseases, lowered serum levels of IGF-1 and IGF-2 have been documented. This was supposed to reflect significant damage to liver parenchyma, a decreased number of growth hormone receptors and a decreased genomic expression of IGF binding proteins (IGF BPs). In HCC, a decreased tissue expression of IGF-1, and an increased expression of IGF-1 receptor (IGF-1R) were noted, compared to the control. Potential mechanisms of augmented IGF-2 expression in HCC were also described and dysregulation of IGF signaling in HCC was concluded to occur predominantly at the level of IGF-2 bioavailability. The review aimed at presentation of involvement of IGF-1, IGF-1R and IGF BPs (mostly IGF BP-3 and IGF BP-6) in HCV-related hepatocarcinogenesis. Manifestation of various mRNA transcripts and IGF-1 proteins and their potential involvement in carcinogenesis are also discussed.

Retinoids ameliorate insulin resistance in a leptin-dependent manner in mice

Transgenic mice expressing dominant-negative retinoic acid receptor (RAR) α specifically in the liver exhibit steatohepatitis, which leads to the development of liver tumors. Although the cause of steatohepatitis in these mice is unknown, diminished hepatic expression of insulin-like growth factor-1 suggests that insulin resistance may be involved. In the present study, we examined the effects of retinoids on insulin resistance in mice to gain further insight into the mechanisms responsible for this condition. Dietary administration of all-trans-retinoic acid (ATRA) significantly improved insulin sensitivity in C57BL/6J mice, which served as a model for high-fat, high-fructose diet-induced nonalcoholic fatty liver disease (NAFLD). The same effect was observed in genetically insulin-resistant KK-A(y) mice, occurring in concert with activation of leptin-signaling pathway proteins, including signal transducer and activator of transcription 3 (STAT3) and Janus kinase 2. However, such an effect was not observed in leptin-deficient ob/ob mice. ATRA treatment significantly up-regulated leptin receptor (LEPR) expression in the livers of NAFLD mice. In agreement with these observations, in vitro experiments showed that in the presence of leptin, ATRA directly induced LEPR gene expression through RARα, resulting in enhancement of STAT3 and insulin-induced insulin receptor substrate 1 phosphorylation. A selective RARα/β agonist, Am80, also enhanced hepatic LEPR expression and STAT3 phosphorylation and ameliorated insulin resistance in KK-A(y) mice.

CONCLUSION

We discovered an unrecognized mechanism of retinoid action for the activation of hepatic leptin signaling, which resulted in enhanced insulin sensitivity in two mouse models of insulin resistance. Our data suggest that retinoids might have potential for treating NAFLD associated with insulin resistance.

Alterations of insulin-like growth factor I (IGF-I) and estradiol serum levels in chronic hepatitis C

Aim of the study

Deregulation of insulin-like growth factor I (IGF-I) production and decreased hepatic estrogen levels were associated with development of hepatocellular carcinoma (HCC) in hepatitis C virus (HCV) infected cirrhotic patients. The aim of our study was to determine serum levels of IGF-I, insulin and 17-β estradiol (17-βE) in relation to other markers of liver injury in chronic hepatitis C (CHC) patients.

Material and methods

Thirty anti-viral treatment-naïve CHC patients and 10 healthy subjects were examined. HCV infection was confirmed by presence of anti-HCV and HCV-RNA in serum. Serum levels of IGF-I, insulin and of 17-βE were evaluated using ELISA methods.

Results

Serum levels of IGF-I and 17-βE were significantly lower in CHC patients than in controls while insulin levels were similar in both groups. A lower IGF-I level (but not the level of 17-βE) was observed in cirrhotic CHC patients in comparison to non-cirrhotic ones. Decreased serum level of IGF-I was associated with more advanced staging and liver steatosis, higher levels of alpha-fetoprotein (AFP) and gamma globulin levels, and higher aspartate transaminase (AST) activity in CHC patients. Insulin and 17-βE levels positively correlated with patient's age. A positive correlation was observed between insulin level on one hand and staging, liver steatosis and levels of gamma globulins in CHC patients on the other. A negative correlation between IGF-I and insulin levels was noted only in HCV infected patients.

Conclusions

Decreased IGF-I levels and increased levels of insulin better than estradiol serum levels characterize staging and liver steatosis in CHC patients. The lower serum level of 17-βE in the CHC group than in control patients suggests that CHC patients carry higher risk of liver injury and of HCC development.