Chronic insulin exposure does not cause insulin resistance but is associated with chemo-resistance in colon cancer cells.

Insulin resistance is an adaptive process in insulin-sensitive tissues characterised by reduced insulin receptor (IR) and insulin-receptor substrate (IRS)-1 expression, increased IRS-1 serine phosphorylation and attenuated downstream signalling. We tested whether this molecular phenotype prevails in cancer cells after long-term exposure to insulin. We characterised expression of IR-related molecules, IRS-1 phosphorylation and downstream signalling in a panel of 5 colon cancer cell lines at different insulin exposures: 15 min (100 nM), approximating to acute stimulation; 48 h (100 nM), used to demonstrate adaptive changes; and 12 weeks (20 nM; chronic insulin exposure, CIE), approximating to chronic hyperinsulinaemia. To assess clinical relevance, we determined IC50 values (increased indicating chemo-resistance) in the CIE-treated cells using oxaliplatin, SN38 (irinotecan) and 5-fluorouracil (5-FU). All colon cancer cell lines (HCT 116, HT-29, C32, CaCo2, LoVo) were sensitive to 15 min insulin exposure with increased phosphorylation of Akt, PRAS40 and p70-S6K. At 48 h, there was incomplete or absent features of insulin resistance. In CIE-treated cells, there was reduced IR expression, incomplete IRS-1 adaptation, lack of signalling pathway attenuation and contra-adaptive increases in IRS-1 tyrosine phosphorylation in several cell types. In CIE cells, there were multiple examples of increased IC50 values (2- to 100-fold) following 24-h treatment with oxaliplatin and SN38, but not with 5-FU. We concluded that CIE in colon cancer cells does not completely induce an insulin resistance molecular phenotype but is associated with chemo-resistance. Adaptive changes seen in insulin-sensitive non-neoplastic cells in response to long-term insulin may not extrapolate to neoplastic cells.

Differential diagnosis of liver diseases using serum biomarkers.

PURPOSE: Many human blood proteins are synthesised in the liver. Their serum levels may decrease or increase due to liver disorders and some of them serve as useful biomarkers. Determination of serum concentration of different biomarkers has important role in diagnosis of liver diseases and in monitoring the course of disease. In this work 3 serum markers associated with liver disorders were compared. The aim was to assess whether these biomarkers exhibit specific distribution pattern in different types of liver disease: liver neoplasia (primary hepatocellular carcinoma [HC] or metastatic liver disease [MLD] from colon cancer), viral hepatitis C (HCV) and the parasitic infection echinococcosis. METHODS: Serum concentrations of alpha-fetoprotein (AFP), ferritin and insulin-like growth factor I (IGF-I) were determined in patients with liver disease and compared between patient groups and with healthy persons. RESULTS: Serum AFP and ferritin levels exhibited similar pattern of change in patients with liver neoplasia or HCV, and concentrations of these 2 markers were significantly increased compared to the control group (p < 0.01 in each case). On the other hand, the concentration of IGF-I was significantly decreased in patients with liver neoplasia or echinococcosis compared to the control group (p < 0.05 for both). The concentration of IGF-I was significantly lower and the concentration of ferritin significantly higher in patients with HC than in patients with MLD from colorectal cancer (p < 0.01 for both). CONCLUSION: The results have shown that each hepatic pathology studied exhibited specific profile of the analysed set of biomarkers. Therefore, the simultaneous determination of the 3 mentioned biomarkers may help in differential diagnosis of liver diseases.

Association of elevated IGFBP-1 with increased IGF-II concentration in patients with carcinoma of the liver.

Insulin-like growth factors (IGFs) are mitogens for numerous types of cells including cancer cells. The aim of this work was to analyze some of the components of the IGF system to assess which could be potential clinical biomarkers for monitoring patients diagnosed with liver cancer. Compared to healthy persons, patients with liver cancer had a lower concentration of IGF-I and a higher concentration of IGFBP-1, whereas the concentrations of IGF-II and IGFBP-3 remained unchanged. The IGF-I:IGFBP-3 ratio decreased in patients with cancer, while the IGF-II:IGFBP-1 ratio was not altered. Patients with primary carcinoma and those scheduled for surgery had lower IGF-I and higher IGF-II and IGFBP-1 concentrations than patients with secondary carcinoma and those not eligible for surgery. It may be postulated that a liver with primary cancer is induced to increase IGF-II and IGFBP-1 synthesis more than a liver involved in metastatic response. Similarly, in patients eligible for liver surgery an increase in IGF-II may reflect a gradual change in the concentration associated with a different stage of disease. As increased synthesis of certain IGFBPs is necessary to compensate decreased production of the others or increased IGF production, determination of serum IGF-II, IGFBP-1 and their ratio may aid in estimating the compensatory capacity of the liver affected by cancer.

The influence of laparoscopic and open surgery on the concentration and structural modifications of insulin-like growth factor binding protein 3 in the human circulation.

Insulin-like growth factor binding protein 3 (IGFBP-3) is the most abundant insulin-like growth factor binding protein in the circulation. The aim of the present work was to investigate the influence of surgery (laparoscopy and open) on the concentration and carbohydrate content of IGFBP-3. The concentration of IGFBP-3 was measured using an immunoradiometric assay (IRMA), its protein profile was characterised using immunoblotting and its sialic acid content was examined by means of Sambucus nigra agglutinin (SNA) affinity chromatography. The concentration of IGFBP-3 was significantly (p < 0.001) lower in preoperative patients compared with healthy subjects. Only patients that underwent open surgery showed a further significant decrease in the concentration of IGFBP-3. Immunoblotting detected two intact IGFBP-3 isoforms, as well as proteolytic fragments. SNA-affinity chromatography showed that in patients that underwent surgery the ratio between the two IGFBP-3 glycoforms was lower than the ratio in healthy subjects. Patients with gallbladder inflammation that underwent laparoscopy had an increased percentage of specifically bound IGFBP-3 to SNA compared with healthy subjects. Our conclusion is that open surgery decreased the level of IGFBP-3 compared with laparoscopy, whereas patients with gallbladder inflammation that underwent laparoscopy had an increased content of sialic acid in IGFBP-3.

Gastrointestinal inflammation and the circulating IGF system in humans.

Insulin-like growth factors (IGFs) and their binding proteins (IGFBPs) have important anabolic functions in normal tissue growth, which in excess may lead to tumorigenesis. In the present study, circulating IGF-I, IGF-II and their binding proteins (IGFBP-3, IGFBP-2 and IGFBP-1) were determined in 92 adult patients with gastrointestinal inflammation (Crohn's disease, colitis ulcerosa, gastritis, duodenitis errosiva, gastrointestinal candidiasis, and rotaviral and adenoviral enteritis). Serum IGF concentrations were measured by radioimmunoassay, while IGFBP profiles and IGFBP proteolytic patterns were characterized by immunoblotting. Concentrations of both IGF-I and IGF-II were significantly (p < 0.001) lower in patients than in healthy subjects. Immunoblotting demonstrated a decreased amount of intact IGFBP-3 (by approximately 60%), whereas IGFBP-2 and IGFBP-1 were increased (approximately 1.7 and 3.5-fold, respectively). No alteration in either fragmentation pattern or relative degree of proteolysis was detected in patients compared to the control group. It may be concluded that the IGF system is seriously imbalanced in patients with gastrointestinal inflammation, regardless of primary cause. These findings may help towards a better understanding of the metabolic outcome of the inflammatory process, and possibly in predicting the efficiency of patient recovery.