Insulin-like Growth factor-II Levels Research Articles

Characteristics of Hepatic IGF-II Expression and Monitored Levels of Circulating IGF-II mRNA in Metastasis of Hepatocellular Carcinoma

The prognosis of hepatocellular carcinoma (HCC) remains dismal. Insulin-like growth factor II (IGF-II), a fetal growth factor, is highly expressed during HCC development. We examined serum IGF-II levels and circulating IGF-II messenger RNA (mRNA) expression and analyzed the clinicopathologic characteristics in patients with liver diseases. The higher IGF-II level in the serum of patients with HCC could be correlated with hepatitis B virus infection but not with patient sex, age, tumor size, or α-fetoprotein (AFP) level. Total RNAs were extracted from liver tissues or peripheral blood mononuclear cells, and IGF-II complementary DNA (cDNA) and AFP cDNA were synthesized through random primers and reverse transcriptase; gene fragments were amplified by nested polymerase chain reaction and confirmed by sequencing. The incidence of the hepatic IGF-II gene was 100% in HCC, 54.3% in paracancerous tissues, and none in noncancerous tissues. The incidence rates for circulating IGF-II and AFP genes were 34.3% and 52.7%, respectively, and for both, 61.6% in patients with HCC. They were 100% in cases with extrahepatic metastasis. The IGF-II abnormality associates with HCC, and circulating IGF-II and IGF-II mRNA are useful molecular markers for HCC differential diagnosis and hematogenous metastasis.

Cervical Scrapes Levels of Insulin-like Growth Factor-II and Insulin-like Growth Factor Binding Protein 3 in Women with Squamous Intraepithelial Lesions and Cervical Cancer

A growing number of studies have demonstrated an association between serum levels of insulin-like growth factors (IGFs) and IGF binding protein-3 (IGFBP-3) and increased risk for various cancers. The aim of this study was to evaluate the relationship between levels of IGF-II or IGFBP-3 in cervical scrapes with cervical cancer and precancerous lesions: low-grade squamous intraepithelial lesion (LSIL) and high-grade squamous intraepithelial lesion (HSIL). 4 groups of cases were examined: LSIL (n=20), HSIL (n=28), cervical cancer (n=45), and controls (n=51). Control subjects were women with normal, HPV DNA-negative Papanicolau (Pap) test. IGF-II and IGFBP-3 levels in cervical scrapes were measured by ELISA. Results show that median protein levels of IGF-II were significantly lower in cervical cancer cases vs. controls (446.5 ng/mg vs. 1,168.6 ng/mg, p<0.001). Significantly higher values of IGFBP-3 were found in HSIL vs. controls (median: 549.5 ng/mg vs. 216 ng/mg; p=0.018), and were not affected by HR HPV infection, meanwhile no significant differences were observed in IGFBP-3 levels between LSIL or cervical cancer as compared to controls. These data suggests that the progression to cervical cancer is associated with alterations in the IGF system and not affected by HR HPV infection. More studies are needed to understand the possible role of IGFBP-3 in cervical carcinogenesis.

The role of feeding regimens in regulating metabolism of sexually mature broiler breeders

A trial was conducted to determine the effects of different rearing feed regimens on plasma hormone and metabolite levels and hepatic lipid metabolism and gene expression on sexually mature broiler breeders. Cobb 500 birds were divided into 2 groups at 4 wk and fed either an everyday (ED) or skip-a-day (SKP) regimen. At 24 wk of age, all birds were switched over to an ED regimen. At 26.4 wk, breeder hens were randomly selected and killed at intervals after feeding. Livers were sampled from 4 hens at 4-h intervals for 24 h for a total of 28 samples per treatment. Blood was sampled from 4 hens per sampling time; sampling times were 0, 30, and 60 min and 2 and 4 h after feeding and then every 4 h up to 24 h for a total of 36 samples per treatment. Main feeding regimen, time, and interaction effects were analyzed. Significant interaction effects were found between time and feeding regimen for acetyl-coenzyme A carboxylase and malic enzyme mRNA expression. The peak for acetyl-coenzyme A carboxylase expression was higher in ED-reared birds, whereas the peak for malic enzyme expression was higher in SKP-reared birds. Overall, plasma levels of insulin-like growth factor-II were higher in SKP-reared birds. Overall, plasma corticosterone levels were also higher in SKP-reared birds and significant interaction effects between time and feeding regimen were seen. The expression of apolipoprotein A1 was significantly higher in ED-reared birds: significant interaction effects were also noted. Other researchers also found some of the differences observed in the present study in 16-wk-old pullets. In summary, different feeding regimens alter metabolic responses, some of which carry over into sexual maturity.

Reply

In Response: We thank Lagiou and colleagues for their insightful letter in which they discuss indirect evidence in support of a possible negative association between circulating levels of insulin-like growth factor II (IGF-II) and breast cancer risk. There is insufficient direct evidence to determine whether or not IGF-II levels influence the risk of breast cancer. To our knowledge, only two small prospective studies have examined the role of IGF-II levels in breast cancer risk with inconsistent results (1, 2). Similarly, few studies have examined the role of IGF-II in mammographic density. Lagiou and colleagues discussed our finding of an unexpected negative association between IGF-II levels and density in premenopausal women, but, as we highlighted in our article, this finding should be interpreted with caution because the association disappeared on adjustment for body mass index. Moreover, no association between IGF-II levels and density was found in another study of premenopausal women (3), although findings from studies conducted among postmenopausal women are more consistent with a possible inverse association (3, 4).Lagiou and colleagues reported higher levels of umbilical cord blood IGF-II in Asians compared with Caucasians. Interestingly, cross-sectional studies suggest that such ethnic gradients may not persist into adulthood, with young adult Asians having significantly lower circulating levels of this growth factor than Caucasians (5), perhaps reflecting ethnic differences in body composition and other lifestyle variables. Similarly, Afro-Caribbean postmenopausal women, known to have a lower breast cancer risk than Caucasians, have been shown to have lower levels of IGF-II (4). In fact, ethnic difference in circulating levels of IGF-II, as well as in levels of IGF-I, IGF-binding protein 3 (IGFBP3), and sex steroid hormones, explained little of the ethnic gradient in mammographic density, which, as expected, was higher among Caucasian than Afro-Caribbean women (4). Unfortunately, no similar comparisons have been carried out among premenopausal women.We agree with Lagiou and colleagues that the associations between IGF-II, mammographic density, and breast cancer risk have thus far been vastly overlooked, and based on the findings of studies of IGF-I and IGFBP3, they should be investigated separately in pre- and postmenopausal women.No potential conflicts of interest were disclosed.

A Case of Gastrointestinal Stromal Tumor with Recurrent Hypoglycemia

Non-islet cell tumor induced hypoglycemia (NICTH) is attributable to overproduction of insulin-like growth factor-II (IGF-II) by solid tumors, and these tumors usually originate from mesenchymal or epithelial cells. Gastrointestinal stromal tumor (GIST) is a rare mesenchymal tumor and most commonly find in the gastrointestinal tract. It is usually expresses the CD117 (stem cell factor receptor, c-kit) detected by immunohistochemistry. Hypoglycemia associated with GIST is very rare and this has not yet been reported in Korea. A 72-year-old man was hospitalized due to frequent episodes of confusion. It was observed that non-hyperinsulinemic hypoglycemia, an elevated serum IGF-II level and a huge liver mass. The histology of liver mass showed c-kit (CD117) positivity, which was consistent with GIST, but it was surgically unresectable. He was treated with imatinib mesylate. Although he recieved palliative treatment, he still experienced intermittent fasting hypoglycemia. After 2 months, the serum IGF-II level was even higher than before. We changed imatinib mesylate to sunitinib malate and performed radiotherapy on the liver mass. Although the change of the liver mass was not significant, he did not suffer from hypoglycemia for three months afterwards.

Enhanced Insulin Sensitivity in Prepubertal Children with Constitutional Delay of Growth and Development

To test the hypothesis that prepubertal children with presumed constitutional delay of growth and development (CDGD) have enhanced insulin sensitivity and, therefore, insulin sensitivity is associated with later onset of puberty. Twenty-one prepubertal children with presumed CDGD and 23 prepubertal control children, underwent a frequently sampled intravenous glucose tolerance test to evaluate insulin sensitivity and other markers of insulin, glucose, and growth regulation. Children in the CDGD group were shorter and leaner than control subjects. Children with presumed CDGD were 40% more insulin sensitive (17.0 x 10(-4) min(-1)/[mU/L] versus 12.1 x 10(-4) min(-1)/[mU/L]; P = .0006) and had reduced acute insulin response, thus maintaining euglycemia (216 mU/L versus 330 mU/L; P = .02) compared with control subjects. In addition, the CDGD group had lower serum insulin-like growth factor binding protein 3 levels (3333 ng/mL versus 3775 ng/mL; P = .0004) and a trend toward lower serum insulin-like growth factor-II levels (794 ng/mL versus 911 ng/mL; P = .06). Prepubertal children with presumed CDGD have enhanced insulin sensitivity, supporting the hypothesis that insulin sensitivity is associated with timing of puberty. It may signify long-term biological advantages with lower risk of metabolic syndrome and malignancy.

Hemangiopericytoma-associated hypoglycemia improved by glucocorticoid therapy: a case report

A 59-year-old man was admitted because of recurrent, severe hypoglycemia. He had multiple metastases from a meningeal hemangiopericytoma, which had been operated on 12 years earlier. The results of laboratory testing at the time of hypoglycemia showed very low serum levels of insulin, C-peptide, and growth hormone, with slightly high levels of insulin-like growth factor-II, and a normal level of insulin-like growth factor-I. The diagnosis of hemangiopericytoma-associated hypoglycemia was proposed. The patient was given corticosteroid therapy, which ameliorated symptoms of hypoglycemia.

Recurrence of Urothelial Carcinoma of the Bladder: A Role for Insulin-Like Growth Factor-II Loss of Imprinting and Cytoplasmic E-Cadherin Immunolocalization

This study documents the frequency of insulin-like growth factor-II (IGF-II) loss of imprinting (LOI) in a series of 87 bladder tissues. E-cadherin (CDH1) immunolocalization was also investigated due to the known redistribution of this adherence protein to the cytoplasm following exogenous exposure to IGF-II. Informative IGF-II cases were identified following DNA-PCR amplification and subsequent sequencing of the transcribable ApaI RFLP in exon 9 of IGF-II. Similar approaches using primer-specific cDNA templates identified the imprinting status of IGF-II in these informative cases. CDH1 cellular localization was assessed on a tissue microarray platform of 114 urothelial carcinoma of the bladder (UCB) cases (70 pT(a) noninvasive and 44 pT(1) lamina propria invasive) using the commercially available Novocastra antibody. IGF-II LOI was evident in 7 of 17 (41%) UCB tumors and 4 of 11 (36%) tumor-associated normal urothelial samples. Two of four pT(1) grade 3 tumors, the subject of much debate concerning their suitability for radical cystectomy, showed LOI at the IGF-II locus. In those tumors showing IGF-II LOI, 4 of 7 (57%) displayed concomitant CDH1 cytoplasmic staining. In contrast, only 3 of 10 (30%) IGF-II maintenance of imprinting tumors had concomitant CDH1 cytoplasmic localization. UCB cell lines displaying cytoplasmic CDH1 immunolocalization expressed significantly higher levels of IGF-II (CAL29, HT1376, and RT112) compared with RT4, a cell line displaying crisp membranous CDH1 staining. Finally, cytoplasmic CDH1 staining was an independent predictor of a shorter time to recurrence independent of tumor grade and stage. We suggest that CDH1 cytoplasmic immunolocalization as a result of increased IGF-II levels identifies those nonmuscle invasive presentations most likely to recur and therefore might benefit from more radical nonconserving bladder surgery.

Comparison of follicular fluid insulin-like growth factor II and insulin-like growth factor binding protein 4 levels between short 7-day and long gonadotropin-releasing hormone agonist protocols

OBJECTIVE: Insulin-like growth factor II (IGF-II) and Insulin-like growth factor binding protein 4 (IGFBP-4) play a major role in the autocrine and paracrine regulation of folliculogenesis. To explore the individual influence on the intrafollicular microenvironment between the short 7-day gonadotropin-releasing hormone agonist (GnRHa) protocol (7-day protocol) and GnRHa long protocol (long protocol) by comparing the concentrations of IGF-II, IGFBP-4, and the ratio of IGF-II/IGFBP-4 in follicular fluid. DESIGN: Prospective randomized controlled study. MATERIALS AND METHODS: 88 infertile patients with tubal factor who accepted IVF treatment from July to October 2007 were included in this study. 7-day protocol group (n=44): GnRHa (decapeptyl, Ferring) was injected 0.1 mg daily from day 2 of the menstrual cycle to day 8. At the same time gonadotropin (Gn) was injected daily from day 3. Long protocol group (n=44): GnRHa (diphereline, Ferring) was injected 1.88 mg singly in the mid-luteal phase of previous menstrual cycle. Once the patient was down regulated, gonadotropin injection was started. Follicular fluid was obtained from dominant follicles during oocyte retrieval. The levels of IGF-II and IGFBP-4 in follicular fluid were detected separately by radioimmunoassay and enzyme-linked immunosorbent assay. RESULTS: The durations of controlled ovarian stimulation was significantly shorter and total dose of Gn used were significantly lower in the 7-day protocol group. The levels of serum E2 and E2 per mature follicle on the day of hCG injection, the number of oocytes retrieved, fertilization rate, cleaved embryos rate, top-quality embryos rate, implantation rate, pregnancy rate, and clinical abortion rate were similar between the two groups. The concentrations of IGF-II (0.17±0.06ng/ml vs 0.20±0.07 ng/ml, P=0.020) and IGFBP-4 (2915.48±1443.02pg/ml vs 3646.64±1818.67pg/ml, P=0.040) in follicular fluid of the 7-day protocol group patients were significantly lower. There was no significant difference in the ratio of IGF-II/IGFBP-4 (0.07±0.04 vs 0.07±0.03, P=0.471) between the 7-day and long protocol group. Linear correlation analysis showed that the level of follicular fluid IGF-II was positively correlated to total dose of Gn used (r=0.316, P <0.05). CONCLUSIONS: The short 7-day and long GnRHa protocols may affect the concentrations of follicular fluid IGF-II and IGFBP-4. However, the changes of follicular fluid IGF-II and IGFBP-4 concentrations may not contribute to different clinical outcomes.

Insulin-like growth factor-II: a novel autocrine growth factor modulating the apoptosis and maturation of umbilical cord blood erythroid progenitors

To search a novel function of erythroid progenitor cells circulating as the major nucleated cell population in umbilical cord blood (CB) cells. Human CB-derived CD36(+) erythroid progenitors were subjected to cDNA microarray. Gene expression and biological property of CB-erythroid progenitors and adult peripheral blood (PB)-erythroid progenitors were compared by using real-time polymerase chain reaction (PCR) and serum-free culture system with erythropoietin (EPO). The microarray revealed 124-fold higher levels of insulin-like growth factor-II (IGF-II) gene expression in CB-CD36(+) erythroid progenitors than in stimulated lymphocytes of adult PB. Real-time PCR verified that IGF-II mRNA levels were highest in CB-CD36(+) erythroid progenitors compared to other CB- or adult PB-fractionated cells. When CB-CD36(+) erythroid progenitors were cultured with EPO in serum-free medium, anti-IGF-II-antibody (Ab) reduced the number of erythroid colonies. When CB- and adult PB-derived erythroid colony-forming cells (ECFCs) were cultured with interleukin-3, stem cell factor, and EPO, mRNA levels per cells of IGF-II peaked on day 12, but those of type 1 and type 2 receptors did not increase with ECFCs maturation. The maturation rate by IGF-II was higher in CB-ECFCs than in adult PB-ECFCs. The majority of CB-ECFCs expressed IGF-II protein. Anti-IGF-II-Ab, but not anti-IGF-I-Ab, reduced the number of CB-ECFCs in liquid culture with EPO. Anti-IGF-II-Ab accelerated apoptosis of ECFCs, assessed by dimethylthiazole tetrazolium bromide, bromodeoxyuridine, and flow cytometric analyses. ECFCs failed to attain full maturity in the presence of anti-IGF-II-Ab. These results suggest that IGF-II is produced by erythroid progenitors themselves, and has a crucial role in fetal erythropoiesis by modulating apoptosis and maturation in an autocrine fashion.

Differential effects of human chorionic gonadotropin and decidualization on insulin-like growth factors-I and -II in human endometrial stromal cells

To investigate insulin-like growth factors (IGF)-I and -II in human endometrial stromal cells during decidualization in vitro and under the influence of hCG. In vitro experiment. Research laboratory at a medical university center. Premenopausal women undergoing hysterectomy for benign reasons. Endometrial stromal cells from hysterectomy specimens were isolated and incubated with 17beta-E(2), P, and recombinant hCG. Insulin-like growth factor-I and -II messenger RNA and protein were measured by semiquantitative real-time reverse transcriptase polymerase chain reaction and ELISA. During decidualization in vitro there was a significant increase of IGF-I level between day 0 and 3, followed by a decrease from day 6 to 9. Insulin-like growth factor-II level, however, was significantly reduced during all days of decidualization compared with day 0. In decidualized endometrial stromal cells, hCG decreased IGF-I in a dose-dependent manner without influencing IGF-II. Endometrial IGF-I and -II are differentially regulated during decidualization in vitro, suggesting different roles during the differentiation of endometrial stromal cells. Human chorionic gonadotropin as one of the first hormonal signals of the embryo selectively reduces IGF-I and may therefore contribute to the modulation of endometrial receptivity and differentiation during the process of early implantation.

A Novel Binding Site for the Human Insulin-like Growth Factor-II (IGF-II)/Mannose 6-Phosphate Receptor on IGF-II

The mammalian insulin-like growth factor (IGF)-II/cation-independent mannose 6-phosphate receptor (IGF2R) binds IGF-II with high affinity. By targeting IGF-II to lysosomal degradation, it plays a role in the maintenance of correct IGF-II levels in the circulation and in target tissues. Loss of IGF2R function is associated with tumor progression; therefore, the IGF2R is often referred to as a tumor suppressor. The interaction between IGF2R and IGF-II involves domains 11 and 13 of the 15 extracellular domains of the receptor. Recently, a hydrophobic binding region was identified on domain 11 of the IGF2R. In contrast, relatively little is known about the residues of IGF-II that are involved in IGF2R binding and the determinants of IGF2R specificity for IGF-II over the structurally related IGF-I. Using a series of novel IGF-II analogues and surface plasmon resonance assays, this study revealed a novel binding surface on IGF-II critical for IGF2R binding. The hydrophobic residues Phe(19) and Leu(53) are critical for IGF2R binding, as are residues Thr(16) and Asp(52). Furthermore, Thr(16) was identified as playing a major role in determining why IGF-II, but not IGF-I, binds with high affinity to the IGF2R.

A Case of Epithelioid Hemangioendothelioma of the Pelvic Retroperitoneum with Hypoglycemia

Hypoglycemia caused by a non-islet cell tumor (NICT) is a rare condition. The mechanism of NICT-induced hypoglycemia is still unclear, but insulin-like growth factor-II (IGF-II) has been thought to play a major role in its development. NICT is usually of mesenchymal or epithelial cell origin, but reports on NICT of an endothelial cell origin, which causes hypoglycemia, have yet to surface. Here, we report on a case of a 63-year-old female patient who was diagnosed with epithelioid hemangioendothelioma-induced hypoglycemia. Epithelioid hemangioendothelioma is a borderline malignant vascular tumor that is of endothelial cell origin and usually occurs in soft tissue, skin, lung, and liver. It was observed that serum insulin, C-peptide, and IGF-I were reduced, but the IGF-II level was elevated in hypoglycemia. The PET-CT showed no abnormal glucose metabolism in the tumor. Dextrose fluid was administered to the patient to control hypoglycemia until the operation. For treatment and diagnosis, surgical resection of the tumor and total hysterectomy were performed. The specimen was noted to have epithelioid hemangioendothelioma. Hypoglycemia-related symptoms disappeared after surgical resection was performed. (J Kor Endocr Soc 22:440~445, 2007)

Insulin-like growth factor-II (IGF-II), IGF-binding protein-3 (IGFBP-3), and IGFBP-4 in follicular fluid are associated with oocyte maturation and embryo development

The objective of this study was to investigate the association between follicular fluid (FF) levels of insulin-like growth factors (IGFs), IGF binding proteins (IGFBPs), and pregnancy-associated plasma protein-A (PAPP-A), which is a protease for IGFBP-4, and the quality of subsequent embryo development from in vitro fertilized oocytes aspirated from the same follicle. Prospective study. University infertility clinic and academic research laboratory. One hundred sixty-two infertile women undergoing controlled ovarian hyperstimulation for IVF and embryo transfer were recruited in a university hospital. During oocyte retrieval, samples of 225 FFs and matched mature oocytes were collected and studied. Concentrations of FF IGF-I, IGF-II, IGFBP-1, IGFBP-3, IGFBP-4, and PAPP-A were determined using ELISA. Progesterone secretion by cultured granulosa cells (GC) was measured by RIA. Levels of IGF-II, IGFBP-3, and IGFBP-4 in FF on the day of oocyte retrieval were significantly correlated with embryo scores on day 3 (72 hours after oocyte retrieval). Levels of IGF-II, IGFBP-3, and IGFBP-4 in FF from follicles in which oocytes developed into day 2 embryos (48 hours after oocyte retrieval; 20 >or= embryo score >or= 6) after fertilization were significantly higher than those from follicles in which oocytes were unable to be fertilized and were arrested in embryo development on day 2, whereas the levels of PAPP-A were significantly lower in the former than the latter group. Using multiple regression analysis, we found that high levels of IGFBP-3 and IGFBP-4 combined with low levels of PAPP-A in FF were significantly correlated with successful fertilization and early development into day 2 embryos. In contrast, high FF IGFBP-1 and IGFBP-4 in combination with low FF IGF-I were significantly correlated with a later (day 2-day 3) embryo development. A significant stimulation of P secretion in cultured GCs by the combination of recombinant IGF-II, IGFBP-3, and IGFBP-4 further strengthened these proteins' functional roles in promoting late follicular development. High IGF-II, IGFBP-3, IGFBP-4, and low PAPP-A levels in FF at the time of oocyte retrieval suggest better oocyte maturation and early embryo development (within 48 hours after oocyte retrieval), whereas high IGFBP-1, IGFBP-4, and low FF IGF-I levels may favor later embryo development (between 48 and 72 hours after oocyte retrieval).

A case of haemangiopericytoma-associated hypoglycaemia: beneficial effect of treatment with radiotherapy

A 72-year-old lady presented with recurrent hypoglycaemia and a large pelvic mass. Hypoglycaemia was accompanied by undetectable serum insulin and c-peptide and high insulin-like growth factor II (IGFII) to IGFI ratio. She had undergone successful resection of a large bladder haemangiopericytoma 7 years earlier. A core biopsy was performed, and histology confirmed the recurrence of the haemangiopericytoma. Local palliative radiotherapy resulted in the reduction of IGFII level and IGFII to IGFI ratio and increased insulin, c-peptide and growth hormone (GH) level with long-term amelioration of hypoglycaemic episodes. Clinically and biochemically, radiotherapy was more effective than GH therapy.

Low Insulin-like Growth Factor-II Levels Predict Weight Gain in Normal Weight Subjects with Type 2 Diabetes

Purpose Insulin-like growth factor (IGF)-I and IGF-II are important in the regulation of metabolism and growth. We previously reported in normoglycemic individuals of normal weight that low circulating IGF-II predicts future weight gain. We subsequently investigated whether such relationships persisted in circumstances of type 2 diabetes. Methods In 224 subjects with type 2 diabetes we assessed the association between baseline IGF-II levels and risk of weight gain (>2.0 kg) at the 5-year follow-up. Results At follow-up, 90 participants (40.2%) gained more than 2.0 kg in body weight. For subjects (body mass index <26) at baseline, mean IGF-II levels were significantly lower in those who gained more than 2 kg in weight than in subjects of stable weight, 454 ng/mL (95% confidence interval 349-559) versus 620 ng/mL (534-705) (F = 7.4, P = .01). For this subgroup low circulating IGF-II at baseline strongly correlated with weight gain (Spearman rho = −0.52, P <.001). With increasing weight, the relationship no longer prevailed. Logistic regression showed that for body mass index less than 26, individuals at baseline for each 100 ng/mL increase in baseline IGF-II there was a 47% decreased risk of gaining 2.0 kg or more in weight. Adjustment for treatment group did not materially alter this relationship. There was no difference in baseline IGF-II by treatment group. There was no difference between the group with weight gain and the group with stable weight in those who additionally received insulin or sulfonylurea treatment in the 5 years between the baseline visit and the follow-up. Conclusions In subjects of normal weight with type 2 diabetes, baseline IGF-II concentration is inversely related to future weight gain, independent of treatment effect, strengthening the putative role for IGF-II in regulating fat mass. We propose that IGF-II measurement has potential utility in this group for targeting such individuals for early intervention.

β1 Integrins Modulate Cell Adhesion by Regulating Insulin-Like Growth Factor-II Levels in the Microenvironment

The interactions between cancer cells and the extracellular matrix (ECM) regulate cancer progression. The beta1C and beta1A integrins, two cytoplasmic variants of the beta1 integrin subfamily, are differentially expressed in prostate cancer. Using gene expression analysis, we show here that the beta1C variant, an inhibitor of cell proliferation, which is down-regulated in prostate cancer, up-regulates insulin-like growth factor-II (IGF-II) mRNA and protein levels. In contrast, beta1A does not affect IGF-II levels. We provide evidence that beta1C-mediated up-regulation of IGF-II levels increases adhesion to Laminin-1, a basement membrane protein down-regulated in prostate cancer, and that the beta1C cytoplasmic domain contains the structural motif sufficient to increase cell adhesion to Laminin-1. This autocrine mechanism that locally supports cell adhesion to Laminin-1 via IGF-II is selectively regulated by the beta1 cytoplasmic domain via activation of the growth factor receptor binding protein 2-associated binder-1/SH2-containing protein-tyrosine phosphatase 2/phosphatidylinositol 3-kinase pathway. Thus, the concurrent local loss of beta1C integrin, of its ligand Laminin-1, and of IGF-II in the tumor microenvironment may promote prostate cancer cell invasion and metastasis by reducing cancer cell adhesive properties. It is, therefore, conceivable that reexpression of beta1C will be sufficient to revert a neoplastic phenotype to a nonproliferative and highly adherent normal phenotype.

IGF-II transgenic mice display increased aberrant colon crypt multiplicity and tumor volume after 1,2-dimethylhydrazine treatment

In colorectal cancer insulin-like growth factor II (IGF-II) is frequently overexpressed. To evaluate, whether IGF-II affects different stages of tumorigenesis, we induced neoplastic alterations in the colon of wild-type and IGF-II transgenic mice using 1,2-dimethylhydrazine (DMH). Aberrant crypt foci (ACF) served as markers of early lesions in the colonic mucosa, whereas adenomas and carcinomas characterized the endpoints of tumor development. DMH-treatment led initially to significantly more ACF in IGF-II transgenic than in wild-type mice. This increase in ACF was especially prominent for those consisting of ≥three aberrant crypts (AC). Nevertheless, adenomas and adenocarcinomas of the colon, present after 34 weeks in both genetic groups, were not found at different frequency. Tumor volumes, however, were significantly higher in IGF-II transgenic mice and correlated with serum IGF-II levels. Immunohistochemical staining for markers of proliferation and apoptosis revealed increased cell proliferation rates in tumors of IGF-II transgenic mice without significant affection of apoptosis. Increased proliferation was accompanied by elevated localization of β-catenin in the cytosol and cell nuclei and reduced appearance at the inner plasma membrane. In conclusion, we provide evidence that IGF-II, via activation of the β-catenin signaling cascade, promotes growth of ACF and tumors without affecting tumor numbers.

Insulin-Like Growth Factor II Is an Autocrine Growth Factor To Prevent Apoptosis as Well as To Enhance Proliferation and Maturation of Erythroid Progenitor Cells.

To reveal the novel function of erythroid progenitor cells in fetal erythropoiesis, the gene expression pattern in umbilical cord blood (CB)-derived CD36+ erythroid progenitor cells (EPCs) was analyzed using cDNA microarray containing 240 cytokine and growth factor related genes. Among the genes analyzed, insulin-like growth factor II (IGF-II) gene showed a 124-fold higher level of expression in CB-EPCs, compared with that seen in phytohemagglutinin (PHA)-stimulated adult peripheral blood mononuclear cells (PBMCs) (table1). Real-time PCR revealed that the IGF-II mRNA levels in CB-EPCs were higher than those seen in lymphocytes or monocytes separated from CB or PBMCs. When CB-EPCs were cultured with erythropoietin (EPO) in serum-free medium, the number of erythroid colonies was decreased in the presence of IGF-II-neutralizing antibody. To further assess the role of IGF-II in erythropoiesis, we purified erythroid colony-forming cells (ECFCs) from human umbilical cord blood by magnetic selection and liquid culture with IL-3, stem cell factor and EPO. The expression levels of IGF-II, type 1 or 2 IGF receptor in the mature ECFCs were higher than those in the immature ECFCs. Addition of IGF-II-neutralizing antibody decreased the number of ECFCs in liquid culture with EPO. The anti-proliferative effect of IGF-II-neutralizing antibody was evident in both dimethylthiazole tetrazolium bromide (MTT) and bromodeoxyuridine (BrdU) incorporation assays. When apoptosis of cells was examined using Annexin V, the addition of IGF-II-neutralizing antibody increased apoptosis, thereby indicating the anti-apoptotic effects of IGF-II secreted from erythroid cells. Furthermore, ECFCs failed to undergo normal erythroid maturation in the presence of IGF-II-neutralizing antibody, as assessed by flow cytometric and morphologic analyses. These findings indicate that IGF-II, which is produced by erythroid progenitor cells themselves, has crucial roles in controlling erythropoiesis by modulating apoptosis, proliferation and maturation via an autocrine mechanism.Cytokine and growth factor genes highly expressed in CB-EPCs selected by cDNA microarray analysesratiogene124.0insulin-like growth factor II7.9vascular endothelial growth factor3.9interleukin 83.4GRO2 oncogene3.0GRO1 oncogene1.6transforming growth factor, beta 11.4vascular endothelial growth factor B

Positive Correlation of Insulin-Like Growth Factor-II with Proliferating Cell Index in Patients with Colorectal Neoplasia

Insulin-like growth factor-II (IGF-II) stimulates cell proliferation and is considered a potential risk factor for colorectal cancer. Tumor levels of IGF-II seem to positively correlate with colorectal cancer cell proliferation. This investigation examined the association of circulating IGF-II to the proliferating cell index (PCI) of tumor and matched normal mucosa in patients with colorectal neoplasia. Circulating IGF-II level (ng/mL) was determined in the peripheral blood plasma by ELISA. The proliferating cells in tumor or matched normal mucosa were immunohistochemically stained using the primary antibody against Ki-67. Computer image analysis was used and PCI was expressed as the percentage of Ki-67-positive cells/total counted cells. Sixty-four patients were evaluated; 45 had colorectal neoplasia (27 males/18 females; mean age, 66.8 +/- 11.8 years) and 19 had hyperplastic polyps (6 males and 13 females; mean age, 58.4 +/- 14.4 years). Among patients with colorectal neoplasia, blood IGF-II levels were positively correlated with PCI in the matched normal mucosa (r = 0.46, P < 0.05) but not in the tumor. In patients with hyperplastic polyps, blood IGF-II levels were not correlated with the PCI in the polyps. Blood IGF-II levels were higher in colorectal cancer patients with Dukes' C/D stage (P < 0.01) or with positive lymph nodes (P < 0.01). Circulating IGF-II positively correlated with PCI in normal colonic mucosa of patients with colorectal neoplasia, suggesting that IGF-II may have a role in initiating the carcinogenic pathway by stimulating cell proliferation. Blood IGF-II was increased in advanced colorectal cancer, indicating that it might enhance colorectal cancer progression and be a useful marker of poor prognosis.