Insulin-like growth factor I and the development of colorectal neoplasia in acromegaly

Insulin-Like Growth Factor 1 (IGF-1) Signaling in Glucose Metabolism in Colorectal Cancer

Colorectal cancer (CRC) is one of the most common aggressive carcinoma types worldwide, characterized by unfavorable curative effect and poor prognosis. Epidemiological data re-vealed that CRC risk is increased in patients with metabolic syndrome (MetS) and its serum components (e.g., hyperglycemia). High glycemic index diets, which chronically raise post-prandial blood glucose, may at least in part increase colon cancer risk via the insulin/insulin-like growth factor 1 (IGF-1) signaling pathway. However, the underlying mechanisms linking IGF-1 and MetS are still poorly understood. Hyperactivated glucose uptake and aerobic glycolysis (the Warburg effect) are considered as a one of six hallmarks of cancer, including CRC. However, the role of insulin/IGF-1 signaling during the acquisition of the Warburg metabolic phenotypes by CRC cells is still poorly understood. It most likely results from the interaction of multiple processes, directly or indirectly regulated by IGF-1, such as activation of PI3K/Akt/mTORC, and Raf/MAPK signaling pathways, activation of glucose transporters (e.g., GLUT1), activation of key glycolytic enzymes (e.g., LDHA, LDH5, HK II, and PFKFB3), aberrant expression of the oncogenes (e.g., MYC, and KRAS) and/or overexpression of signaling proteins (e.g., HIF-1, TGF-β1, PI3K, ERK, Akt, and mTOR). This review describes the role of IGF-1 in glucose metabolism in physiology and colorectal carcinogenesis, including the role of the insulin/IGF system in the Warburg effect. Furthermore, current therapeutic strategies aimed at repairing impaired glucose metabolism in CRC are indicated.

Patin (Pangasius hypophthalmus) fish protein concentrate alters insulin-like growth factor (IGF)-1 and igf binding protein (IGFBP)-3 level of sprague dawley neonate rats-induced malnutrition

Malnutrition is caused by inadequate protein intake and affects growth factor. High protein from patin (Pangasius hypophthalmus) fish is a well-known protein source. This study aims to investigate the effect of patin fish protein concentrate (PFPC) in the IGF-1 and IGFBP-3 level of Sprague Dawley (SD) neonate rats-induced malnutrition. Thirty male SD neonate rats were divided randomly into five groups, namely normal control (K1), malnutrition control (K2), malnutrition with PFPC 13.26 mg.g-1 body weight (BW)/day (X1), malnutrition with PFPC 19.89 mg.g-1 BW/d (X2), and malnutrition with casein supplement 13.26 mg.g-1 BW/d (X3). K1 received a standard diet, while the others received a low 8% protein diet (L8PD) since those were born until 21 days. The standard diet was refed for all groups during the intervention (14 days). IGF-1 and IGFBP-3 levels were measured by ELISA. Normal data were analyzed by using One-way ANOVA which then was followed by post-hoc Bonferroni. Meanwhile, the others were analyzed by Kruskal Wallis and followed by Mann-Whitney U-test. Spearman test was used for correlation. PFPC contained 81.07% of protein, 4.08% of fat, 7.24% of moisture, 2.77% of ash, and 4.83% of carbohydrate. These contents had affected the growth factor. As a result, in the PFPC intervention, IGF-1, and IGFBP-3 levels (p <0.05) were decreased, while the controls were increased. The decreased values were shown in IGFBP-3 levels (p <0.05) while the increase was shown in both controls. On the other hand, the increase in body weight was shown in all groups, including control ones. A strong correlation was found between IGF-1 and IGFBP-3. PFPC has additional value on repairing malnutrition that is the best dose in effecting IGF-1 dan IGFBP3 levels is 13.26 mg.g-1 BW/d.

Energy Restriction and Colorectal Cancer: A Call for Additional Research

: Colorectal cancer has the second highest cancer-related mortality rate, with an estimated 881,000 deaths worldwide in 2018. The urgent need to reduce the incidence and mortality rate requires innovative strategies to improve prevention, early diagnosis, prognostic biomarkers, and treatment effectiveness. Caloric restriction (CR) is known as the most robust nutritional intervention that extends lifespan and delays the progression of age-related diseases, with remarkable results for cancer protection. Other forms of energy restriction, such as periodic fasting, intermittent fasting, or fasting-mimicking diets, with or without reduction of total calorie intake, recapitulate the effects of chronic CR and confer a wide range of beneficial effects towards health and survival, including anti-cancer properties. In this review, the known molecular, cellular, and organismal effects of energy restriction in oncology will be discussed. Energy-restriction-based strategies implemented in colorectal models and clinical trials will be also revised. While energy restriction constitutes a promising intervention for the prevention and treatment of several malignant neoplasms, further investigations are essential to dissect the interplay between fundamental aspects of energy intake, such as feeding patterns, fasting length, or diet composition, with all of them influencing health and disease or cancer effects. Currently, effectiveness, safety, and practicability of different forms of fasting to fight cancer, particularly colorectal cancer, should still be contemplated with caution.

Colonic Cancer and Acromegaly

Acromegaly results in a significantly increased morbidity and mortality due to cardiovascular and respiratory complications, as well as malignancies arising mainly from the colon. Furthermore, an increased lifetime risk of malignant transformation of pre-malignant colonic lesions relates to a worse overall prognosis from colorectal cancer, which is currently considered a major disease-related complication. In this review we provide some insight into colonic changes in this condition, summarize current knowledge and evidence on the use of colonoscopic screening in patients with acromegaly, and suggest a recommended screening protocol.

Guidelines versus real life practice: the case of colonoscopy in acromegaly

PURPOSE

The aim of this study is to investigate guideline application and colonoscopy findings in real-life practice in acromegaly.

METHODS

We conducted a retrospective observational non-interventional and cross-sectional analysis on 146 patients with acromegaly (ACRO) referred to our clinic. We evaluated colonoscopy data, focusing on the correlation between colonoscopy findings and hormonal/metabolic values.

RESULTS

The total number of colonoscopies performed in ACRO patients increased from 6 in the period 1990-1994 to 57 in the period 2010-2014. Colonoscopy procedures were performed according to guidelines in 25% of ACRO patients at diagnosis, 51% at follow-up and 11% globally (both at diagnosis and follow-up). Among the 146 ACRO patients, 68% were subjected to at least one colonoscopy and in 32% of the cases a polyp was detected during the procedure. The presence of polyps was significantly associated with mean levels of growth hormone (GH), insulin-like growth factor 1 (IGF-1), fasting glucose and insulin levels (p < 0.05). Polyps were detected in 48% of untreated patients and in 26% of patients under treatment for acromegaly (p = 0.04). The general risk of polyps and adenomatous polyps in ACRO patients was higher compared to the control population of Veneto Region, Italy (odds ratio 1.33 and 1.16, respectively). No cancerous polyps were detected in our analysis.

CONCLUSION

In real-life practice, adherence to ACRO colonoscopy clinical guidelines was lower than expected. Among patients who underwent colonoscopy, the prevalence of colon polyps was higher for ACRO patients, suggesting the need for new strategies to ensure adherence to colonoscopy guidelines.

Patients with Acromegaly Presenting with Colon Cancer: A Case Series

Introduction. Frequent colonoscopy screenings are critical for early diagnosis of colon cancer in patients with acromegaly. Case Presentations. We performed a retrospective analysis of the incidental diagnoses of colon cancer from the ACCESS trial (ClinicalTrials.gov identifier: NCT01995734). Colon cancer was identified in 2 patients (4.5%). Case  1 patient was a 36-year-old male with acromegaly who underwent transsphenoidal surgery to remove the pituitary adenoma. After surgery, the patient underwent routine colonoscopy screening, which revealed a 40 mm tubular adenoma in the descending colon. A T1N1a carcinoma was surgically removed, and 1 of 22 lymph nodes was positive for metastatic disease, leading to a diagnosis of stage 3 colon cancer. Case  2 patient was a 50-year-old male with acromegaly who underwent transsphenoidal surgery to remove a 2 cm pituitary adenoma. The patient reported severe cramping and lower abdominal pain, and an invasive 8.1 cm³ grade 2 adenocarcinoma with signet rings was identified in the ascending colon and removed. Of the 37 lymph nodes, 34 were positive for the presence of tumor cells, and stage 3c colon cancer was confirmed. Conclusion. Current guidelines for colonoscopy screening at the time of diagnosis of acromegaly and at appropriate follow-up intervals should be followed.

Is there a role for IGF-1 in the development of second primary cancers?

Cancer survival rates are increasing, and as a result, more cancer survivors are exposed to the risk of developing a second primary cancer (SPC). It has been hypothesized that one of the underlying mechanisms for this risk could be mediated by variations in insulin-like growth factor-1 (IGF-1). This review summarizes the current epidemiological evidence to identify whether IGF-1 plays a role in the development of SPCs. IGF-1 is known to promote cancer development by inhibiting apoptosis and stimulating cell proliferation. Epidemiological studies have reported a positive association between circulating IGF-1 levels and various primary cancers, such as breast, colorectal, and prostate cancer. The role of IGF-1 in increasing SPC risk has been explored less. Nonetheless, several experimental studies have observed a deregulation of the IGF-1 pathway, which may explain the association between IGF-1 and SPCs. Thus, measuring serum IGF-1 may serve as a useful marker in assessing the risk of SPCs, and therefore, more translational experimental and epidemiological studies are needed to further disentangle the role of IGF-1 in the development of specific SPCs.

Considering GH replacement for GH-deficient adults with a previous history of cancer: a conundrum for the clinician

Previous studies have shown that GH and IGF-I may enhance tumorigenesis, metastasis, and cell proliferation in humans and animals. Evidence supporting this notion is derived from animal model studies, epidemiological studies, experience from patients with acromegaly, molecular therapeutic manipulation of GH and IGF-I actions, and individuals with GH receptor and congenital IGF-I deficiencies. Prior exposure to radiation therapy, aging, family history of cancer, and individual susceptibility may also contribute to increase this risk. Therefore, the use of GH replacement in patients with a history of cancer raises hypothetical safety concerns for patients, caregivers, and providers. Studies of GH therapy in GH-deficient adults with hypopituitarism and childhood cancer survivors have not convincingly demonstrated an increased cancer risk. Conversely, the risk of occurrence of a second neoplasm (SN) in childhood cancer survivors may be increased, with meningiomas being the most common tumor; however, this risk appears to decline over time. In light of these findings, if GH replacement is to be considered in patients with a previous history of cancer, we propose this consideration to be based on each individual circumstance and that such therapy should only be initiated at least 2 years after cancer remission is achieved with the understanding that in some patients (particularly those with childhood cancers), GH may potentially increase the risk of SNs. In addition, close surveillance should be undertaken working closely with the patient's oncologist. More long-term data are thus needed to determine if GH replacement in GH-deficient adults with a history of cancer is associated with the development of de novo tumors and tumor recurrence.

The role of colonoscopic screening in acromegaly revisited: review of current literature and practice guidelines

INTRODUCTION

Acromegaly is a chronic, debilitating and disfiguring condition with a significantly increased morbidity and mortality due to cardiovascular, as well as respiratory complications. Patients with acromegaly are usually diagnosed at the age of 40, however, the duration of symptoms can vary from 5 to 10 years before the formal diagnosis is confirmed. Recent advances in the field of acromegaly have improved survival significantly. A strong association between acromegaly and premalignant colonic lesions and colon cancer has been highlighted. Furthermore, patients with acromegaly have a greater lifetime risk of malignant transformation and a far worse overall prognosis from colorectal cancer, which is now considered a major disease related complication.

MATERIALS AND METHODS

A comprehensive search strategy was applied for the Medline/PubMed electronic database from its inception until April 2014. We considered all human research articles published in English, not classified as case report, editorial, comment, letter, or news.

CONCLUSION

Specific recommendations for large bowel endoscopic screening in patients with acromegaly have been proposed. In this comprehensive review we discuss the current state of knowledge and evidence on colonoscopic screening in patients with acromegaly illustrated by a case of aggressive colorectal cancer presenting late in a young woman with difficult to control acromegaly.

GSK1838705A, an IGF-1R inhibitor, inhibits glioma cell proliferation and suppresses tumor growth in vivo

Glioma is a type of primary malignant tumor of the central nervous system in humans. At present, standard treatment involves surgical resection, followed by radiation therapy and chemotherapy. However, the prognosis is poor and the long-term survival rate remains low. An improved understanding of the molecular basis for glioma tumorigenesis is in urgently required. The pro-survival effect of the insulin-like growth factor (IGF) signaling pathway has been implicated in progression of the glioma disease state. GSK1838705A is a novel, small molecule kinase inhibitor of IGF-IR, which inhibits IGF signal transduction and downstream target activation. Its anti-proliferative activity has been demonstrated in various tumor cell lines. The present study investigated the potential use of GSK1838705A for the treatment of glioma. Human U87MG glioma cells were used to examine the inhibitory activity of GSK1838705A in cell proliferation, migration and apoptosis. The antitumor activity of GSK1838705A was assessed in a xenograft mouse model. GSK1838705A inhibited the growth and induced the apoptosis of the U87MG glioma cells in a dose-dependent manner. The GSK1838705A-treated cells exhibited reduced migratory activity in response to chemoattractants. The present study further demonstrated the antitumor activity of GSK1838705A in vivo. The administration of GSK1838705A significantly inhibited the growth of glioma tumors by inducing the apoptosis of tumor cells. These results suggested that targeting IGF signaling with GSK1838705A may be a promising therapeutic strategy for the treatment of patients with glioma.

The prevalence and associated factors of colorectal neoplasms in acromegaly: a single center based study

PURPOSE

Colorectal neoplasms are well known to be a complication in cases of acromegaly; however, data on the prevalence of colorectal neoplasms in Asian patients with acromegaly are limited. Further, the factors associated with colorectal neoplasms in cases of acromegaly are controversial. Therefore, we aimed to clarify the prevalence of and factors associated with colorectal neoplasms in Japanese patients with acromegaly in a single center.

METHODS

We analyzed consecutive 57 patients who had undergone full-length colonoscopy at the time of diagnosis at Kobe University Hospital between 1986 and 2012.

RESULTS

Of the 57 patients, 22 (38.6%), 18 (31.6%) and 3 (5.3%) patients were diagnosed with hyperplastic polyps, adenomas, and adenocarcinomas, respectively and the prevalence was significantly higher than in a historical control group, Chinese patients with irritable bowel syndrome (The odds ratio was 4.0, 8.7, and 17.5, respectively). The prevalence of adenocarcinomas was also significantly higher in these patients than in the general Japanese population (odds ratio 14.5). Patients with acromegaly who had colorectal neoplasms had longer disease duration than those without colorectal neoplasms. Of note, the area under the growth hormone (GH) concentration-time curve (GH AUC) during the oral glucose tolerance test was significantly higher in patients with adenocarcinomas than in those with no colonic lesion or those with hyperplastic polyps.

CONCLUSION

Japanese patients with acromegaly exhibited an increased risk of colorectal neoplasms, especially colorectal adenocarcinomas. An increased GH AUC was associated with an increased risk for colon adenocarcinomas in patients with acromegaly.

Synchronous esthesioneuroblastoma and growth-hormone-secreting pituitary macroadenoma: combined open and endoscopic management

Background Esthesioneuroblastoma is an uncommon malignant neoplasm that arises from the olfactory neuroepithelium. In this article we report a case of esthesioneuroblastoma presenting concomitantly with a growth-hormone (GH)-secreting pituitary macroadenoma. Results A 52 year old woman underwent surgery for suspected nasal polyps. Intralesional debulking of an intranasal tumor disclosed a low-grade esthesioneuroblastoma. Magnetic resonance imaging (MRI) demonstrated a large nasal and intracranial tumor, in addition to a separate sellar and suprasellar tumor. The patient was frankly acromegalic. She underwent a first-stage gross total resection of the esthesioneuroblastoma via a combined extended subfrontal and extended endonasal approach, followed by focused radiation therapy. She then returned for endoscopic removal of the GH-secreting pituitary macroadenoma. Conclusion The combined open and endoscopic management of this patient is described and a review of the literature presented. To our knowledge this is the first case of synchronous esthesioneuroblastoma and macroadenoma, in this case GH secreting, described in the literature.

MTHFR C677T polymorphism, folate status and colon cancer risk in acromegalic patients

BACKGROUND

Acromegalic patients have a higher risk of developing colorectal tumours (CRT). The common C677T polymorphism in methylenetetrahydrofolate reductase (MTHFR) gene is a well-documented CRT risk factor in the general population, but its role in acromegaly has never been examined.

PURPOSE

We investigated the influence of MTHFR C677T polymorphism, folate status and other lifestyle, nutritional and disease-specific variables on CRT risk in acromegaly.

METHODS

Clinical data were collected from 115 acromegalic patients (25 with active disease) who underwent a complete colonoscopy. C677T MTHFR genotype, homocysteine, vitamin B12, insulin growth factor and insulin levels, as well as metabolic variables were evaluated.

RESULTS

Colorectal tumours were identified in 51 patients (3 adenocarcinomas). MTHFR C677T distribution was in the Hardy-Weinberg equilibrium and similar in patients with or without CRT. There was a correlation between patients with TT genotype and CRT occurrence (Spearman's test: P = 0.03), with an Odds Ratio (OR) of 1.32 (95% CI 0.522-3.362, P NS). A folate-MTHFR genotype interaction on CRT risk was found (P = 0.037): in the lower folate subgroup, TT patients showed a 2.4 higher OR for CRT (95% CI 0.484-11.891; P NS) than C-allele carriers. Smoking (P = 0.007), increased HbA1c levels (P = 0.021), dyslipidaemia (P = 0.049), acromegaly control (P = 0.057), and folate-MTHFR genotype interaction (P = 0.088) were associated with CRT at multivariate analysis.

CONCLUSIONS

In this cohort of acromegalic patients, CRT risk is increased in 677TT MTHFR patients with low plasma folate levels. Smoking, high HbA1c levels, dyslipidaemia and disease activity were also associated with increased CRT risk.

Adverse health consequences of performance-enhancing drugs: an Endocrine Society scientific statement

Despite the high prevalence of performance-enhancing drug (PED) use, media attention has focused almost entirely on PED use by elite athletes to illicitly gain a competitive advantage in sports, and not on the health risks of PEDs. There is a widespread misperception that PED use is safe or that adverse effects are manageable. In reality, the vast majority of PED users are not athletes but rather nonathlete weightlifters, and the adverse health effects of PED use are greatly underappreciated. This scientific statement synthesizes available information on the medical consequences of PED use, identifies gaps in knowledge, and aims to focus the attention of the medical community and policymakers on PED use as an important public health problem. PED users frequently consume highly supraphysiologic doses of PEDs, combine them with other PEDs and/or other classical drugs of abuse, and display additional associated risk factors. PED use has been linked to an increased risk of death and a wide variety of cardiovascular, psychiatric, metabolic, endocrine, neurologic, infectious, hepatic, renal, and musculoskeletal disorders. Because randomized trials cannot ethically duplicate the large doses of PEDs and the many factors associated with PED use, we need observational studies to collect valid outcome data on the health risks associated with PEDs. In addition, we need studies regarding the prevalence of PED use, the mechanisms by which PEDs exert their adverse health effects, and the interactive effects of PEDs with sports injuries and other high-risk behaviors. We also need randomized trials to assess therapeutic interventions for treating the adverse effects of PEDs, such as the anabolic-androgen steroid withdrawal syndrome. Finally, we need to raise public awareness of the serious health consequences of PEDs.

Mathematical modelling to restore circulating IGF-1 concentrations in children with Crohn's disease-induced growth failure: a pharmacokinetic study

OBJECTIVES

Children with Crohn's disease grow poorly, and inflammation depresses the response of insulin-like growth factor-1 (IGF-1) to growth hormone. Correcting the inflammation normalises growth velocity; however, removing inflammation cannot be achieved in all children. Our lack of understanding of IGF-1 kinetics has hampered its use, particularly as high IGF-1 concentrations over long periods may predispose to colon cancer. We hypothesised that mathematical modelling of IGF-1 would define dosing regimes that return IGF-1 concentrations into the normal range, without reaching values that risk cancer.

DESIGN

Pharmacokinetic intervention study.

SETTING

Tertiary paediatric gastroenterology unit.

PARTICIPANTS

8 children (M:F; 4:4) entered the study. All completed: 5 South Asian British; 2 White British; 1 African British.

INCLUSION CRITERIA

Children over 10 years with active Crohn's disease (C reactive protein >10 mg/l or erythrocyte sedimentation rate >25 mm/h) and height velocity <-2 SD score.

EXCLUSION CRITERIA

closed epiphyses; corticosteroids within 3 months; neoplasia or known hypersensitivity to recombinant human IGF-1 (rhIGF-1).

INTERVENTIONS

Subcutaneous rhIGF-1 (120 μg/kg) per dose over two admissions: the first as a single dose and the second as twice daily doses over 5 days.

PRIMARY OUTCOME

Significant increase in circulating IGF-1.

SECONDARY OUTCOMES

Incidence of side effects of IGF-1. A mathematical model of circulating IGF-1 (Ac) was developed to include parameters of endogenous synthesis (Ksyn); exogenous uptake (Ka) from the subcutaneous dose (As): and IGF-1 clearance: where dAc/dt=Ksyn - Kout×Ac+Ka×As.

RESULTS

Subcutaneous IGF-1 increased concentrations, which were maintained on twice daily doses. In covariate analysis, disease activity reduced Ksyn (p<0.001). Optimal dosing was derived from least squares regression fitted to a dataset of 384 Crohn's patients, with model parameters assigned by simulation.

CONCLUSIONS

By using age, weight and disease activity scaling in IGF-1 dosing, over 95% of children will have normalised IGF-1 concentrations below +2.5 SDs of the normal population mean, a level not associated with cancer risk.

Thyroid cancer in patients with acromegaly: a case-control study

Several studies have associated acromegaly with an increased risk of benign and malignant tumors. While simple and multinodular goiters are common findings in acromegaly, the prevalence of thyroid cancer is uncertain. The objective of this study was to estimate the prevalence of thyroid cancer in a series of acromegalic patients from three hospitals in northeast of Brazil. The methodology used included morphological, cytological and histological thyroid analysis of acromegalic patients and volunteers over 18 years, matched for age and sex and with nodule (s) ≥1 cm. The subjects of this study were 124 acromegalic patients, including 76 females (61.3%) and 48 men (38.7%), with a mean age 45.1 years. Results of the study showed that thyroid ultrasonography was normal in 31 cases (25%), 25 had diffuse goiter (20.1%), 67 had nodules (54%) and one agenesis of the right lobe (0.8%). Thirty-six patients underwent fine needle aspiration biopsy (FNAB) of their nodules and 9 cases of papillary cancer were found (7.2%). The control group consisted of 263 subjects, 156 females (59.3%) and 107 males (40.7%), mean age 44.7 years. In ultrasound assessment, 96 had nodules (36.5%). Of these, 13 were punctured and 2 cases of papillary carcinoma were found (0.7%). These results gave an odds ratio of 10.21 (p = 0.0011, 95% CI 2.17 to 48.01). These findings demonstrate an increased prevalence of thyroid cancer, statistically significant when compared to our control group. Thus, it is suggested that acromegalic patients should be routinely submitted to thyroid ultrasound evaluation, followed by FNAB of nodules when indicated.

Insulin, insulin-like growth factor 1 and insulin-like growth factor binding protein 3 serum concentrations in patients with adenomatous colon polyps

INTRODUCTION

Insulin stimulates colonic mucosal cells proliferation directly and by influencing the concentration of insulin-like growth factor 1 (IGF-1) and insulin-like growth factor binding protein 3 (IGFBP-3).

AIM

To estimate serum concentrations of insulin, IGF-1, and IGFBP-3 and to determine the relationships between them and colorectal adenoma location, dysplasia grading, histological type, and size.

MATERIAL AND METHODS

The study included 60 patients with colorectal adenomatous polyps found on colonoscopy and confirmed pathologically. The control group consisted of 30 individuals with no positive findings on colonoscopy. All patients had their blood drawn for assessment of insulin, IGF-1, and IGFBP-3 serum concentrations.

RESULTS

One hundred and nine adenomas (6-40 mm in size) were found in 60 study patients. The average age of patients with multiple polyps was significantly higher than that of patients with single pathologies (61.1 vs. 56.7 years respectively (p < 0.05)). A higher adenoma incidence rate was observed in the distal portion of the colon than the proximal one (50 vs. 10 polyps respectively (p < 0.01)). Higher serum levels of IGF-1 and IGFBP-3 were found in patients with adenomatous polyps than in the control group. The average IGF-1 concentration in patients with adenomas located proximally was also significantly higher compared to those located distally (p < 0.05). The insulin concentration was similar in both groups and not related to clinical data of patients.

CONCLUSIONS

The results indicate the role of IGF-1 and IGFBP-3 in early carcinogenesis of the large intestine, and IGF-1 particularly in malignant transformation in the proximal part of the organ.

Influence of Obesity and Related Metabolic Alterations on Colorectal Cancer Risk

Obesity and related metabolic alterations have been implicated to play a role in colorectal cancer risk. The metabolic syndrome, as assessed according to current international definitions by the key components, abdominal obesity, dyslipidemia, elevated blood pressure, and abnormal glucose metabolism, is associated with colorectal cancer. Recent studies suggest that abdominal obesity and abnormal glucose metabolism may primarily account for this association. Visceral adipose tissue is physiologically more active than subcutaneous adipose tissue and generates hormones and cytokines with inflammatory, metabolic, and direct carcinogenic potential, which may directly or indirectly increase colorectal cancer risk. Current evidence suggests that obesity acts as a risk factor for colorectal cancer by several mechanisms, including chronic low-grade inflammation, hyperinsulinemia, as well as alterations in insulin-like growth factor and adipokine concentrations. Metabolic biomarkers reflecting these processes may not only provide clues for etiological understanding of colorectal carcinogenesis but also might be an alternative way to define an "obesity phenotype" that is relevant for colorectal cancer development.

The insulin-like growth factor system in cancer

Insulin-like growth factor (IGF) plays an important role in tissue growth and development. Several studies have demonstrated the association between circulating levels of IGF-1 and -2 and cancer risk, and the IGF system has been implicated in the oncogenesis of essentially all solid and hematologic malignancies. The optimal strategy for targeting IGF signaling in patients with cancer is not clear. The modest benefits reported thus far underscore the need for a better understanding of IGF signaling, which would enable clinicians to identify the subset of patients with the greatest likelihood of attaining benefit from this targeted approach.

Colonic neoplasia in acromegaly: increased proliferation or deceased apoptosis?

Patients with acromegaly have higher prevalence of colorectal neoplasms. The pathogenetic mechanism is still unclear and may be related to sustained increase in serum GH-IGF1. We aimed to evaluate the proliferative and apoptotic markers in samples of colonic mucosa obtained during screening colonoscopic biopsy from patients with acromegaly and study their relationship to serum IGF-1 and GH levels. The study subjects included 32 patients with acromegaly (4 female), 10 healthy controls (irritable bowel syndrome) and 10 positive controls (non-acromegalic colonic adenocarcinoma). Patients with acromegaly were divided into two groups, active disease (AD) and disease in remission (AR). Two biopsies each were obtained during colonoscopy from the right colon, transverse colon and rectosigmoid region. All the polyps were biopsied and subjected to histopathological examination. Immunohistochemistry for proliferation marker (Ki-67) and apoptotic markers (caspase-3 and TdT-Mediated dUTP Nick-End Labeling (TUNEL) was carried out in the histopathological samples. Indices of proliferation were significantly different in patients with acromegaly as compared to healthy controls. The mean Ki-67 positivity was 45.1 ± 17.7% in AD and 45.6 ± 23.1% in AR, as compared to 10 ± 5% in healthy controls. While none of the healthy controls had Ki-67 positivity beyond the lower third of crypts, among patients with acromegaly 12/32 (37.5%) had mid-third positivity (P = 0.000) and 15/32 (46.8%) had full length of crypt positively (P = 0.00). Immunostaining for caspase-3 was negative in patients with acromegaly and healthy controls. TUNEL was strongly positive in patients with colonic adenocarcinoma but not in healthy controls and patients with acromegaly. IGF-1 levels were higher in those with Ki-67 positivity in the superficial mucosa. Patients with acromegaly have increased proliferation of colonic epithelial cells. Elevated levels of serum IGF1 are associated with increase proliferation in the superficial crypt cells.

Characterisation of a functional intronic polymorphism in the human growth hormone (GH1) gene

The +1169A allele of the A/T single nucleotide polymorphism (SNP; rs2665802), located within intron 4 of the human growth hormone I (GHI) gene, has been associated with reduced levels of circulating GH and insulin-like growth factor I, a reduced risk of colorectal cancer and a predisposition to osteoporosis. Whether this intronic SNP is itself the functional polymorphism responsible for exerting a direct effect on GHI gene expression, however, or whether it is instead in linkage disequilibrium with the functional SNP, has been an open question. The evolutionary conservation of the +1169T allele (and the surrounding intronic sequence) in the bovine genome, as well as in primate genomes, is, however, suggestive of its functionality. Although a potential alternative splice site spans the location of the +1169 SNP, polymerase chain reaction-based assays failed to yield any evidence for alternative splicing associated with either allele. To determine whether the +1169 SNP, in different allelic combinations with SNPs at -278 (G/T), -57 (T/G) and +2103 (C/T), exerts a direct effect on gene expression and/or GH secretion, we performed a series of transfections of various GHI haplotype-expressing constructs into rat GC (somatotroph) cells. The results obtained provided evidence to support the contention that the +1169A allele contributes directly to the observed reduction in both GHI gene expression and GH secretion. Part of the apparent influence of the +1169A-bearing allele on GHI gene expression and GH secretion may still, however, be attributable to alleles of additional SNPs in cis to +1169A and located within either the promoter or the 3^'-flanking region.

Repeat dose study of the cancer chemopreventive agent resveratrol in healthy volunteers: safety, pharmacokinetics, and effect on the insulin-like growth factor axis

Resveratrol, a naturally occurring polyphenol, has cancer chemopreventive properties in preclinical models. It has been shown to downregulate the levels of insulin-like growth factor-1 (IGF-I) in rodents. The purpose of the study was to assess its safety, pharmacokinetics, and effects on circulating levels of IGF-I and IGF-binding protein-3 (IGFBP-3) after repeated dosing. Forty healthy volunteers ingested resveratrol at 0.5, 1.0, 2.5, or 5.0 g daily for 29 days. Levels of resveratrol and its metabolites were measured by high performance liquid chromatography-UV in plasma obtained before and up to 24 hours after a dose between days 21 and 28. IGF-I and IGFBP-3 were measured by ELISA in plasma taken predosing and on day 29. Resveratrol was safe, but the 2.5 and 5 g doses caused mild to moderate gastrointestinal symptoms. Resveratrol-3-O-sulfate, resveratrol-4'-O-glucuronide, and resveratrol-3-O-glucuronide were major plasma metabolites. Maximal plasma levels and areas under the concentration versus time curve for the metabolites dramatically exceeded those for resveratrol, in the case of areas under the concentration versus time curve, by up to 20.3-fold. Compared with predosing values, the ingestion of resveratrol caused a decrease in circulating IGF-I and IGFBP-3 (P<0.04 for both), respectively, in all volunteers. The decrease was most marked at the 2.5 g dose level. The results suggest that repeated administration of high doses of resveratrol generates micromolar concentrations of parent and much higher levels of glucuronide and sulfate conjugates in the plasma. The observed decrease in circulating IGF-I and IGFBP-3 might contribute to cancer chemopreventive activity.

Comparison of colonoscopy and fecal occult blood testing as a first-line screening of colonic lesions in patients with newly diagnosed acromegaly

CONTENT

Patients with acromegaly have frequently colonic neoplasms; however, how acromegalic patients should be screened for colonic lesions is still unsettled.

AIMS

To compare fecal occult blood testing (FOBT) and colonoscopy in the screening program of patients with acromegaly.

DESIGN

Colonoscopy and FOBT were performed at the first diagnosis of acromegaly.

SETTING

Tertiary University center.

PATIENTS

Eighty-five consecutive patients with untreated active acromegaly submitted to colonoscopy and FOBT.

RESULTS

FOBT, which was positive in 16 (18.8%) out of 85 patients, identified 2 patients with colonic adenocarcinoma and 2 with adenoma; the remaining 12 patients had no detectable colonic lesions. Colonoscopy revealed colonic lesions in 29 patients: 3 (3.5%) cancers, 11 (12.9%) adenomas, and 15 (17.6%) hyperplastic polyps. The remaining 56 acromegalic patients had no detectable lesions. A patient with cancer and 9 patients with adenoma were missed if screened only by FOBT.

CONCLUSIONS

Colonoscopy is superior to FOBT in detecting colonic lesions at the first diagnosis of acromegaly.

Reduced susceptibility to azoxymethane-induced aberrant crypt foci formation and colon cancer in growth hormone deficient rats

OBJECTIVES

To evaluate the role of GH in colon carcinogenesis, we examined the formation of aberrant crypt foci (ACFs) and tumor development in wild type (WT) and GH-deficient, spontaneous dwarf rats (SDRs) exposed to the carcinogen azoxymethane (AOM).

DESIGN

ACF were quantified by stereomicroscopy and tumor number and weights were recorded for each animal. Cell proliferation was measured by vincristine metaphase arrest, flow cytometry, and bromodeoxyuridine (BrdU) incorporation. Apoptosis was measured by TUNEL staining and cleaved caspase-3 immunohistochemistry. IGF-I was measured by radioimmunoassay (RIA). Hexokinase activity was measured by spectrophotometric assay. PARP cleavage, and IGF-IR, and p27(kip/cip) expression were measured by Western blotting.

RESULTS

ACFs detected by stereomicroscopy were markedly reduced ( approximately 85%) in SDRs vs. WT rats at 10, 25, and 28 weeks after AOM. Tumor incidence, number, and weight also were reduced in SDR vs. WT animals. AOM treatment increased cell proliferation in the distal colon (where tumors occur) of WT rats but not SDRs, and these changes corresponded to increased ACF and tumor formation. Apoptosis rates were similar in AOM-treated WT and SDRs. Alterations in serum IGF-I levels may contribute to differences in the proliferative response to AOM and decreased ACF formation in SDR vs. WT rats.

CONCLUSIONS

We conclude that early neoplastic lesions (ACFs) were reduced in GH-deficient animals. This effect corresponds with differences in AOM-induced proliferation, but not apoptosis. These data indicate that GH is required for the full effect of AOM on colon ACF and tumor development, and that the SDR rat is a promising model for studies regarding the role of GH/IGF system in the initiation and promotion of colon cancer.

Number of aberrant crypt foci associated with adiposity and IGF1 bioavailability

BACKGROUND

Dysregulation of the insulin-like growth factor (IGF) system, a common consequence of adiposity-induced insulin resistance, may be a key underlying mechanism linking excess body weight with colon cancer. Evidence has been derived from studies of cancer and polyps. Supporting data about aberrant crypt foci (ACF), putative pre-polyp changes, have been generated only from animal studies to date.

METHODS

We randomly selected 26 patients with sex-specific elevated waist-hip-ratio (WHR) and 26 with normal values from a series of 150 patients seeking routine colonoscopy at the University of Connecticut Health Center. Cross-sectional analyses were performed of ACF number (<5, > or = 5) in relation to total IGF1, IGF-binding protein-3 (IGFBP3), insulin, body mass index (BMI), WHR and waist circumference (WC). Visualized ACF in the 20 cm of the distal colon were counted using advanced endoscopic imaging.

RESULTS

Patients with > or = 5 ACF had higher BMI, WHR, and WC compared with patients with >5 ACF (p = 0.04, p = 0.03, and p = 0.01, respectively). IGFBP3 was reduced (p = 0.02) and IGF1:IGFBP3 molar ratio was greater (p = 0.03) in patients with > or = 5 ACF. We did not observe significant associations between ACF number and insulin or total IGF1.

CONCLUSIONS

Our study provides the first report in humans of a possible association of ACF prevalence and IGF1 bioavailability as characterized by IGF1:IGFBP3 molar ratio and IGFBP3 level. More research is needed to determine whether this relationship is varied by ACF features (e.g., size, dysplasia, molecular changes), synchronous cancer and polyps, and is modified by colon cancer risk factors.

Insulin-like growth factor-1 is essential to the increased mortality caused by excess growth hormone: a case of thyroid cancer and non-Hodgkin's lymphoma in a patient with pituitary acromegaly

The effects of growth hormone are mediated in part by stimulating the production of insulin-like growth factor-1. Insulin-like growth factor-1 has significant effects on cell proliferation and differentiation, it is a potent mitogen, and it is a powerful inhibitor of programmed cell death (apoptosis). Insulin-like growth factor-1 also has a well-established role in the transformation of normal cells to malignant cells. Case reports on a possible association between elevated growth hormone and cancer risk in a variety of patient groups have been published. Here, we describe clinical and laboratory findings for a patient with acromegaly who first developed thyroid cancer, and then, in the follow up period, probably due to poorly controlled insulin-like growth factor-1 levels, developed a large cell non-Hodgkin's lymphoma. A search revealed that a case with these peculiarities had not previously been reported.

Risk of colorectal neoplasm in patients with acromegaly: A meta-analysis

AIM: To examine the risk of colorectal neoplasm in acromegalic patients by meta-analyzing all relevant controlled studies.

METHODS: Extensive English language medical literature searches for human studies, up to December 2007, were performed using suitable keywords. Pooled estimates [odds ratio (OR) with 95% confidence intervals (CI)] were obtained using either the fixed or random-effects model as appropriate. Heterogeneity between studies was evaluated with the Cochran Q test whereas the likelihood of publication bias was assessed by constructing funnel plots. Their symmetry was estimated by the adjusted rank correlation test.

RESULTS: For hyperplastic polyps the pooled ORs with 95% CI were 3.557 (2.587-4.891) by fixed effects model and 3.703 (2.565-5.347) by random effects model. The Z test values for overall effect were 7.81 and 6.984, respectively (P < 0.0001). For colon adenomas the pooled ORs with 95% CI were 2.486 (1.908-3.238) (fixed effects model) and 2.537 (1.914-3.364) (random effects model). The Z test values were 6.747 and 6.472, respectively (P < 0.0001). For colon cancer the pooled OR with 95% CI was identical for both fixed and random effects model (OR, 4.351; 95% CI, 1.533-12.354; Z = 2.762, P = 0.006). There was no significant heterogeneity and no publication bias in all the above meta-analyses.

CONCLUSION: Acromegaly is associated with an increased risk of colorectal neoplasm.

Acromegaly

Acromegaly is caused by growth hormone hypersecretion, mostly from a pituitary adenoma, driving insulin-like growth factor 1 overproduction. Manifestations include skeletal and soft tissue growth and deformities; and cardiac, respiratory, neuromuscular, endocrine, and metabolic complications. Increased morbidity and mortality require early and tight disease control. Surgery is the treatment of choice for microadenomas and well-defined intrasellar macroadenomas. Complete resection of large and invasive macroadenomas rarely is achieved; hence, their low rate of disease remission. Pharmacologic treatments, including long-acting somatostatin analogs, dopamine agonists, and growth hormone receptor antagonists, have assumed more importance in achieving biochemical and symptomatic disease control.

Gallbladder villous adenoma in a patient with acromegaly: A case report

Villous adenomas are benign epithelial lesions with malignant potential that can occur in any part of the gastrointestinal tract. We present a case of a middle age woman with acromegaly who was investigated for nonspecific gastrointestinal complaints. Ultrasonography and subsequent endosonography diagnosed a large (4.5 cm), hyperechoic, sessile polyp with numerous pedicles. An open cholecystectomy was performed and revealed a villous adenoma with several foci of carcinoma in situ. Detailed investigations showed no other tumors of the gastrointestinal tract. After five years of follow-up, the patient reports no complaints, and the results of laboratory testing and imaging studies are within the normal range.

Colorectal neoplasm and acromegaly

The risk for colorectal carcinoma in acromegaly remains controversial. In our earlier study, we have demonstrated that the risk of colorectal carcinoma in Asian Indians with acromegaly is not increased and after this report, routine colonoscopy in our patients with acromegaly was abandoned. Subsequently, two consecutive young men aged 30 and 35, one 6 years after and other at the time of diagnosis of acromegaly had colorectal carcinoma respectively. None of them had family history of colonic neoplasm. These two younger patients with no other predisposition for colorectal neoplasm suggests that colonoscopy should be done in all patients with acromegaly at diagnosis and they should remain under surveillance.

Insulin resistance, apoptosis, and colorectal adenoma risk

Compelling evidence from epidemiologic studies indicates that elevated circulating insulin-like growth factor (IGF)-I, insulin resistance, and associated complications, such as elevated fasting plasma insulin, glucose and free fatty acids, glucose intolerance, increased body mass index, and visceral adiposity, are linked with increased risk of colorectal cancer. However, the role of insulin and markers of glucose control in the development of adenomas, precursors to colorectal cancer, has not been fully explored. We evaluated the relationship between plasma insulin, glucose, IGF-I, IGF-II, IGF-binding protein-3 (IGFBP-3), apoptosis, and colorectal adenomas in a case-control study. Participants were drawn from consenting patients undergoing colonoscopy at the University of North Carolina hospitals (Chapel Hill, NC). Participants were classified as cases or controls based on whether they had one or more colorectal adenomatous polyps. Fasting plasma insulin, IGF-I, IGF-II, and IGFBP-3 levels were assessed by ELISA. Glucose was measured by glucose hexokinase assay. Apoptosis was assessed by morphology on H&E-stained sections. Dietary and lifestyle information were obtained by telephone interview. Logistic regression was used to examine the association between adenoma status and insulin-IGF markers. Adenoma cases (n = 239) and adenoma-free controls (n = 517) provided rectal biopsies and/or blood samples and interview data. Consistent with prior findings, cases were more likely to be males, older, have higher waist-to-hip ratio, lower calcium intake, lower apoptosis, and less likely to report nonsteroidal anti-inflammatory drug use. Those in the highest quartile of insulin (adjusted odds ratio, 2.2; 95% confidence interval, 1.1-4.2) and glucose (adjusted odds ratio, 1.8; 95% confidence interval, 0.9-3.6) were more likely to have an adenoma compared with the lowest quartile. Similarly, subjects in the highest two quartiles of insulin were more likely to be in the lowest two quartiles of apoptosis. Overall, there were no significant differences between mean circulating levels of glucose, IGF-I, IGF-II, and IGFBP-3 among cases and controls and no association between these variables and apoptosis. The results provide novel evidence that elevated insulin and glucose are associated with increased adenoma risk and decreased apoptosis in normal rectal mucosa. These findings suggest that insulin may act early in the adenoma-carcinoma sequence to promote the development of colorectal adenoma by decreasing apoptosis in the normal mucosa.

The role of the insulin-like growth factor system in colorectal cancer: review of current knowledge

BACKGROUND

The insulin-like growth factor system, which includes insulin-like growth factors (IGF-I and IGF-II), IGF receptors (IGF-IR and IGF-IIR) and IGF binding proteins (IGFBPs), plays an important role in epithelial growth, anti-apoptosis and mitogenesis. There is a growing body of evidence showing that IGFs control growth and proliferation of several types of cancer. This review introduces the latest information on the biology of the IGF system and its pathophysiological role in the development of colorectal cancer.

DISCUSSION

The growth promoting effects of IGF-I and IGF-II on cancer cells are mediated through the IGF-IR, which is a tyrosine kinase and cancer cells with a strong tendency to metastasise have a higher expression of the IGF-IR. Most of the IGFs in circulation are bound to the IGFBPs, which regulate the bioavailability of the IGFs. All IGFBPs inhibit IGF action by high affinity binding, while some of them also potentiate the effects of IGFs. Colon cancer cells produce specific proteases that degrade the IGFBP so that the IGF will be free to act on the cancer cell in an autocrine manner. Therefore, the IGFBPs play a crucial role in the development of the cancer.

CONCLUSION

The current knowledge about the link between IGFs and colon cancer is mainly based on in vitro investigations. Further in vivo study is needed to understand the exact role of the IGF system, especially its binding proteins, so that they can be manipulated for the prevention and treatment of colorectal cancer.

Lymphocyte subset pattern in acromegaly

Immune function in acromegalic patients has been poorly investigated. The aim of this study was to evaluate the main surface antigen clusters of circulating lymphocytes in acromegaly. One hundred patients with active acromegaly (55 women and 45 men, aged 20-70 yr) and 200 healthy subjects sex- and age-matched with the patients (110 women and 90 men, aged 20-70 yr) were enrolled in this study. All patients and controls were born and live in Southern Italy. No patient had received octreotide, bromocriptine or corticosteroids for at least 3 months before entering the study. The analysis of lymphocyte subset pattern was performed by flow cytometry and fluorescein isothiocyanate or phycoerythrin directly conjugated monoclonal antibodies specific for the cell surface antigen clusters (CD) representing T-cell population as a whole (CD3), T helpers (CD4), T suppressors (CD8), natural killer cells (CD16) and B-cell population as a whole (CD19). Acromegalics had significantly increased levels of CD3 (67.1+/-7.2 vs 64.3+/-8.8%; p=0.03) and CD4 (37.8+/-3.5 vs 36.4+/-4.3%; p=0.004) and decreased levels of CD8 (31.4+/-3.3 vs 33.7+/-8.2%; p<0.01) and CD19 (12.1+/-3.1 vs 15.2+/-5.1; p=0.01) without age-difference. The results of the current study demonstrate an increase in T-cell activity together with a decrease in B-cell activity in a very large series of patients with active acromegaly. These data further support the existence of abnormalities of the immune system in patients with chronic GH/IGF-1 excess.

Oncological complications of excess GH in acromegaly

Around fifteen percent of the deaths reported in acromegaly are attributable to malignancy (SM Melmed, J Clin Endocrinol Metab 2001;86:2929-2934; A Mestrón, SM Webb, In: Endocrine Society, San Francisco, June 2002 (abstract)), uncontrolled disease is associated with a growth advantage for concurrent neoplasms, which are more likely to be aggressive; however, there is no clear evidence of de novo cancer initiation in acromegaly and no proven causal relationship of acromegaly with malignant disease. Overall and cancer mortality in acromegaly have been shown to correlate with the degree of GH control; if post therapy GH is controlled, both the overall and cancer mortality do not appear to differ from that of the normal population (SM Orme et al., J Clin Endocrinol Metab 1998;83:2730-2734; JD Nabarro, Clin Endocrinol 1987;26:481-512). However, no long-term prospective evaluation of cancer prevalence or its relation to biochemical or clinical disease activity is available. IGF-1 appears to exert a permissive effect on tumorigenesis; there is no clear evidence that tumor initiation is triggered by IGF-1 in acromegaly; nevertheless, since IGF-1 may be higher in neoplasms, aggressive treatment aimed at controlling the disease activity will theoretically be advantageous for acromegalic patients with cancer. The prevalence of colon polyps and colon cancer appear to be incresed in acromegaly as is mortality for colon cancer (Orme et al., 1998), so regular colonoscopy screening and polypectomy would seem advisable, especially in older patients with active acromegaly. Surveillance for prostate cancer in elderly males with high IGF-1, especially if also receiving testosterone replacement therapy, is recommendable, by measurement of serum PSA, rectal examination and/or prostatic ultrasound. In women, mammography should be offered, especially after the age of 50 years, as in the normal population. Neither prostate nor breast cancer have been consistently shown to have an increased prevalence in acromegaly, but larger prospective epidemiological studies are required to study this further.