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P41 Serum levels of insulin-like growth factor-I and oncogenic human papillomavirus natural history
S54
Poster Presentations / Growth Hormone & IGF Research 20 (2010) S39–S81
The effects of insulin and IGFs on stem cell growth and selfrenewal were evaluated by sphere size and sphere-forming assay, respectively. We found that thyrospheres express high levels of IGF-IR and IR-A transcripts. The IGF-IR:IR-A ratio was in favor of IGF-IR, more markedly in normal than in cancer thyrospheres. Both IGFIR and IR-A dramatically dropped in differentiating cells. Cell differentiation was also associated by IR isoform switch from a predominant IR-A to a predominant IR-B expression. Both IGFII and IGF-I were expressed in thyrospheres but were markedly downregulated in differentiating thyrocytes. Both IGF-I and IGF-II induced sphere size increase without affecting self-renewal. In conclusion, our data indicate that: (a) both IGF-IR and IR-A mediate the effects of IGF-II in human thyroid stem cells, although IGF-IR is predominantly expressed; (b) IR-A may play a more important role in cancer than in normal stem cells; (c) cell stemness is associated with a predominant IR-A, while cell differentiation is associated with isoform switch from IR-A to IR-B. These data may help devising new therapeutic anti-cancer strategies. P40 Proinsulin mediates proliferative effects by activating the isoform a of the insulin receptor A. Sacco1 , R. Malaguarnera1 , G. Pandini2 , R. Vigneri2 , A. Belfiore1 . 1 Department of Clinical and Experimental Medicine, Endocrinology Unit, University Magna Graecia of Catanzaro, Catanzaro, Italy; 2 Department of Internal Medicine and Medical Specialties, Endocrinology Unit, University of Catania, Catania, Italy Pathological conditions characterized by hyperinsulinemia, such as diabetes type 2 (T2DM) and obesity, are associated with increased cancer risk. The molecular mechanisms responsible for insulin mitogenic activity in cancer cells include high affinity binding to insulin receptor isoform A (IR-A), and low affinity binding to insulin-like growth factor receptor (IGF-IR), as both receptors are frequently overexpressed in cancer cells. Hyperinsulinemic patients also show an increased proinsulin (Pro-I):insulin ratio. It is, therefore, possible that Pro-I may contribute to cancer risk in these patients by activating the IR-A and/or IGF-IR. To evaluate whether Pro-I may bind to IR-A and/or to IGF-IR and whether Pro-I may mediate biological effects through these receptors, we employed the mouse fibroblast cells R− /IR-A and R+ that overexpress only IR-A or IGF-IR, respectively. R− /IR-B cells expressing only the second IR isoform, IR-B, were used as control. Various human cancer cell lines previously characterized for IR isoforms and IGF-IR expression were also used. We found that Pro-I binds to and phosphorylates IR-A with high affinity, whereas binds to IR-B, with a much lower affinity than to IR-A and does not exert any activity in R+ cells. Evaluation of biological effects in a panel of human cancer cells showed that Pro-I significantly induces both cell proliferation and migration. In conclusion, Pro-I binds to and activates IR-A, but not IGF-IR or IR-B, at nanomolar concentrations, resembling the behavior of IGF-II. Pro-I is, therefore, a new player among factors associated with cancer risk in insulin resistant patients. These findings may have implications in establishing new preventive and/or therapeutic approaches for a large population of patients at risk for cancer. P41 Serum levels of insulin-like growth factor-I and oncogenic human papillomavirus natural history 2 1 1 M.-L. Serrano1 , G. Hernandez ´ , M. Sanchez-G ´ omez ´ . Chemistry, Universidad Nacional de Colombia, Bogot´ a, Colombia; 2 Subdirecci´ on de Investigaciones, Instituto Nacional de Cancerolog´ıa, Bogot´ a, Colombia
Background: High serum levels of insulin-like growth factor-I (IGF-I) are reported to be a risk factor for several common cancers,
including prostate cancer, breast cancer, and colon cancer. Persistent infection with high-risk types of HPV is the main risk factor for the development of cervical cancer. However, HPV infections are selflimited and revert spontaneously, with only a small group of women developing cervical cancer. Recent cross-sectional data suggest a possible association of IGF-I with natural history of oncogenic HPV infection. Objective: To establish whether there is any correlation between IGF-I serum levels and natural history of oncogenic human papillomavirus (HPV). Methods: We conducted a nested case-control study within a prospective populational-based cohort of 2200 women followed-up during ten years (Bogota cohort) for study human papillomavirus natural history. We selected as a case, women who had oncogenic HPV infection and normal cytology result, and as a control, women with normal cytology result who never had oncogenic HPV infection during the follow-up. Total IGF-I was measured by ELISA (DSL, Webster, TX). Results: We retrieved serum sample from 62 cases and 106 controls. Of the 62 cases 15 got HPV infection at baseline (prevalent), 18 got transient HPV infection (clearance before 18 months) and 29 got persistent infection (more than 18 months of duration). Women with persistent and prevalent HPV infection showed higher IGF-I serum levels than those observed in controls and women with transient infection (41.38%, 40% 24.53% and 16.67% in the 4th quartile, respectively). Multinomial logistic regression results, adjusted by age, menarche, smoking parity and hormonal contraceptives showed that high IGF-I serum levels were associated with persistence (lower vs higher quartile: RR 2.60 95% CI 0.61– 10.94) and prevalent (lower vs higher quartile: RR 2.67, 95% CI 0.37–19.09) oncogenic HPV infection but there were not statically significant. Conclusion: Our analysis resulting from a prospective cohort study, do not support previous reported from cross section data about the association of IGF-I and the natural history of HPV infection. P42 Metformin displays antiproliferative activities in endometrial cancer cells via interaction with the IGF-1R signaling axis H. Werner1 , Y. Friedman1 , R. Sarfstein1 , Z. Attias-Geva1 , A. Fishman2 , I. Bruchim2 . 1 Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv, Israel; 2 Gynecology Oncology, Meir Medical Center, Kfar Saba, Sackler School of Medicine, Tel Aviv, Israel Accumulating epidemiological evidence shows that obesity is associated with an increased risk of several types of adult cancers. Recently, metformin, an oral anti-diabetic drug, was shown to exert an anti-neoplastic effect in breast and ovarian cancer cells. The mechanism/s responsible for this non-classical metformin action, however, remain unclear. The insulin-like growth factors (IGFs) play a prominent role in cancer biology and their mechanisms of action are tightly interconnected to the insulin signaling pathways. Given the cross-talk between the insulin and IGF signaling pathways, the aim of this study was to examine the hypothesis that the anti-proliferative actions of metformin are potentially mediated via suppression of the IGF-I receptor (IGF-IR) pathway. To this end, human endometrioid (ECC-1, Ishikawa) and serous papillary (USPC-1, USPC-2) endometrial cancer cell lines were treated with metformin (10 mmol/L) in the absence or presence of IGF-I during the last 20 min of the incubation. Results of Western blots with antiphospho-peptide antibodies revealed that metformin abrogated the IGF-I-induced IGF-IR phosphorylation. This effect was associated with a reduction in Akt phosphorylation. In addition, metformin activated AMPK and reduced mTOR phosphorylation. Of interest, metformin was able to abrogate the anti-apoptotic action of IGF-I, as measured by PARP cleavage. Finally, metformin had a potent inhibitory effect on cell proliferation. Taken together, our data
Poster Presentations / Growth Hormone & IGF Research 20 (2010) S39–S81
The effects of insulin and IGFs on stem cell growth and selfrenewal were evaluated by sphere size and sphere-forming assay, respectively. We found that thyrospheres express high levels of IGF-IR and IR-A transcripts. The IGF-IR:IR-A ratio was in favor of IGF-IR, more markedly in normal than in cancer thyrospheres. Both IGFIR and IR-A dramatically dropped in differentiating cells. Cell differentiation was also associated by IR isoform switch from a predominant IR-A to a predominant IR-B expression. Both IGFII and IGF-I were expressed in thyrospheres but were markedly downregulated in differentiating thyrocytes. Both IGF-I and IGF-II induced sphere size increase without affecting self-renewal. In conclusion, our data indicate that: (a) both IGF-IR and IR-A mediate the effects of IGF-II in human thyroid stem cells, although IGF-IR is predominantly expressed; (b) IR-A may play a more important role in cancer than in normal stem cells; (c) cell stemness is associated with a predominant IR-A, while cell differentiation is associated with isoform switch from IR-A to IR-B. These data may help devising new therapeutic anti-cancer strategies. P40 Proinsulin mediates proliferative effects by activating the isoform a of the insulin receptor A. Sacco1 , R. Malaguarnera1 , G. Pandini2 , R. Vigneri2 , A. Belfiore1 . 1 Department of Clinical and Experimental Medicine, Endocrinology Unit, University Magna Graecia of Catanzaro, Catanzaro, Italy; 2 Department of Internal Medicine and Medical Specialties, Endocrinology Unit, University of Catania, Catania, Italy Pathological conditions characterized by hyperinsulinemia, such as diabetes type 2 (T2DM) and obesity, are associated with increased cancer risk. The molecular mechanisms responsible for insulin mitogenic activity in cancer cells include high affinity binding to insulin receptor isoform A (IR-A), and low affinity binding to insulin-like growth factor receptor (IGF-IR), as both receptors are frequently overexpressed in cancer cells. Hyperinsulinemic patients also show an increased proinsulin (Pro-I):insulin ratio. It is, therefore, possible that Pro-I may contribute to cancer risk in these patients by activating the IR-A and/or IGF-IR. To evaluate whether Pro-I may bind to IR-A and/or to IGF-IR and whether Pro-I may mediate biological effects through these receptors, we employed the mouse fibroblast cells R− /IR-A and R+ that overexpress only IR-A or IGF-IR, respectively. R− /IR-B cells expressing only the second IR isoform, IR-B, were used as control. Various human cancer cell lines previously characterized for IR isoforms and IGF-IR expression were also used. We found that Pro-I binds to and phosphorylates IR-A with high affinity, whereas binds to IR-B, with a much lower affinity than to IR-A and does not exert any activity in R+ cells. Evaluation of biological effects in a panel of human cancer cells showed that Pro-I significantly induces both cell proliferation and migration. In conclusion, Pro-I binds to and activates IR-A, but not IGF-IR or IR-B, at nanomolar concentrations, resembling the behavior of IGF-II. Pro-I is, therefore, a new player among factors associated with cancer risk in insulin resistant patients. These findings may have implications in establishing new preventive and/or therapeutic approaches for a large population of patients at risk for cancer. P41 Serum levels of insulin-like growth factor-I and oncogenic human papillomavirus natural history 2 1 1 M.-L. Serrano1 , G. Hernandez ´ , M. Sanchez-G ´ omez ´ . Chemistry, Universidad Nacional de Colombia, Bogot´ a, Colombia; 2 Subdirecci´ on de Investigaciones, Instituto Nacional de Cancerolog´ıa, Bogot´ a, Colombia
Background: High serum levels of insulin-like growth factor-I (IGF-I) are reported to be a risk factor for several common cancers,
including prostate cancer, breast cancer, and colon cancer. Persistent infection with high-risk types of HPV is the main risk factor for the development of cervical cancer. However, HPV infections are selflimited and revert spontaneously, with only a small group of women developing cervical cancer. Recent cross-sectional data suggest a possible association of IGF-I with natural history of oncogenic HPV infection. Objective: To establish whether there is any correlation between IGF-I serum levels and natural history of oncogenic human papillomavirus (HPV). Methods: We conducted a nested case-control study within a prospective populational-based cohort of 2200 women followed-up during ten years (Bogota cohort) for study human papillomavirus natural history. We selected as a case, women who had oncogenic HPV infection and normal cytology result, and as a control, women with normal cytology result who never had oncogenic HPV infection during the follow-up. Total IGF-I was measured by ELISA (DSL, Webster, TX). Results: We retrieved serum sample from 62 cases and 106 controls. Of the 62 cases 15 got HPV infection at baseline (prevalent), 18 got transient HPV infection (clearance before 18 months) and 29 got persistent infection (more than 18 months of duration). Women with persistent and prevalent HPV infection showed higher IGF-I serum levels than those observed in controls and women with transient infection (41.38%, 40% 24.53% and 16.67% in the 4th quartile, respectively). Multinomial logistic regression results, adjusted by age, menarche, smoking parity and hormonal contraceptives showed that high IGF-I serum levels were associated with persistence (lower vs higher quartile: RR 2.60 95% CI 0.61– 10.94) and prevalent (lower vs higher quartile: RR 2.67, 95% CI 0.37–19.09) oncogenic HPV infection but there were not statically significant. Conclusion: Our analysis resulting from a prospective cohort study, do not support previous reported from cross section data about the association of IGF-I and the natural history of HPV infection. P42 Metformin displays antiproliferative activities in endometrial cancer cells via interaction with the IGF-1R signaling axis H. Werner1 , Y. Friedman1 , R. Sarfstein1 , Z. Attias-Geva1 , A. Fishman2 , I. Bruchim2 . 1 Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv, Israel; 2 Gynecology Oncology, Meir Medical Center, Kfar Saba, Sackler School of Medicine, Tel Aviv, Israel Accumulating epidemiological evidence shows that obesity is associated with an increased risk of several types of adult cancers. Recently, metformin, an oral anti-diabetic drug, was shown to exert an anti-neoplastic effect in breast and ovarian cancer cells. The mechanism/s responsible for this non-classical metformin action, however, remain unclear. The insulin-like growth factors (IGFs) play a prominent role in cancer biology and their mechanisms of action are tightly interconnected to the insulin signaling pathways. Given the cross-talk between the insulin and IGF signaling pathways, the aim of this study was to examine the hypothesis that the anti-proliferative actions of metformin are potentially mediated via suppression of the IGF-I receptor (IGF-IR) pathway. To this end, human endometrioid (ECC-1, Ishikawa) and serous papillary (USPC-1, USPC-2) endometrial cancer cell lines were treated with metformin (10 mmol/L) in the absence or presence of IGF-I during the last 20 min of the incubation. Results of Western blots with antiphospho-peptide antibodies revealed that metformin abrogated the IGF-I-induced IGF-IR phosphorylation. This effect was associated with a reduction in Akt phosphorylation. In addition, metformin activated AMPK and reduced mTOR phosphorylation. Of interest, metformin was able to abrogate the anti-apoptotic action of IGF-I, as measured by PARP cleavage. Finally, metformin had a potent inhibitory effect on cell proliferation. Taken together, our data