Acromegaly and colorectal cancer: a comprehensive review of epidemiology, biological mechanisms, and clinical implications

Acromegaly and Cancer: An Update

Acromegaly is a chronic and rare disease. The diagnosis usually takes several years. Multiple comorbidities are associated with acromegaly. Long-term exposure to growth factors may lead to complications such as the development of benign or malignant tumors. However, the association between acromegaly and cancer remains a matter of debate due to multiple limitations in epidemiological data. There is controversy between acromegaly and mortality, but evidence shows a significant improvement in mortality rates with disease control and careful management of comorbidities. Older age, increased growth hormone levels (GH) at last follow-up, higher insulin-like growth factor-1 (IGF-1) levels at diagnosis, malignancy and radiotherapy were proposed as independent predictors of mortality. In this review we summarize the current state of knowledge in this field. Incidence of different cancer types is described. Rigorous surveillance of endocrine diseases may contribute to increased tumor detection. Personalized screening should probably be recommended.

Oxidative Stress Linking Obesity and Cancer: Is Obesity a 'Radical Trigger' to Cancer?

Obesity is on the rise worldwide, and consequently, obesity-related non-communicable diseases are as well. Nutritional overload induces metabolic adaptations in an attempt to restore the disturbed balance, and the byproducts of the mechanisms at hand include an increased generation of reactive species. Obesity-related oxidative stress causes damage to vulnerable systems and ultimately contributes to neoplastic transformation. Dysfunctional obese adipose tissue releases cytokines and induces changes in the cell microenvironment, promoting cell survival and progression of the transformed cancer cells. Other than the increased risk of cancer development, obese cancer patients experience higher mortality rates and reduced therapy efficiency as well. The fact that obesity is considered the second leading preventable cause of cancer prioritizes the research on the mechanisms connecting obesity to cancerogenesis and finding the solutions to break the link. Oxidative stress is integral at different stages of cancer development and advancement in obese patients. Hypocaloric, balanced nutrition, and structured physical activity are some tools for relieving this burden. However, the sensitivity of simultaneously treating cancer and obesity poses a challenge. Further research on the obesity-cancer liaison would offer new perspectives on prevention programs and treatment development.

Metabolism and Colorectal Cancer

Reprogrammed metabolism is a hallmark of colorectal cancer (CRC). CRC cells are geared toward rapid proliferation, requiring nutrients and the removal of cellular waste in nutrient-poor environments. Intestinal stem cells (ISCs), the primary cell of origin for CRCs, must adapt their metabolism along the adenoma-carcinoma sequence to the unique features of their complex microenvironment that include interactions with intestinal epithelial cells, immune cells, stromal cells, commensal microbes, and dietary components. Emerging evidence implicates modifiable risk factors related to the environment, such as diet, as important in CRC pathogenesis. Here, we focus on describing the metabolism of ISCs, diets that influence CRC initiation, CRC genetics and metabolism, and the tumor microenvironment. The mechanistic links between environmental factors, metabolic adaptations, and the tumor microenvironment in enhancing or supporting CRC tumorigenesis are becoming better understood. Thus, greater knowledge of CRC metabolism holds promise for improved prevention and treatment.

Growth hormone and gastrointestinal malignancy: An intriguing link

Growth hormone (GH) excess is associated with several systemic complications, one of which is the increased risk of neoplastic processes particularly of the gastrointestinal (GI) tract. Among the GI neoplasms, the most reported association is with benign and malignant neoplasms of the colon. In the majority of published literature, an increased incidence of GI neoplasms, both colonic adenomas as well as colorectal carcinoma is reported. However, the studies on colon cancer-specific mortality rate are conflicting with recent studies reporting similar cancer-specific mortality rates in comparison to controls. Many studies have reported an association of colorectal neoplasms with GH levels. Pathogenic mechanisms put forward to explain this association of GH excess and GI neoplasms primarily involve the increased GH-insulin-like growth factor 1 (IGF-1) signaling. Both GH and IGF-1 have proliferative, anti-apoptotic, and angiogenic effects on the systemic tissues leading to cellular proliferation. Other contributing factors to the increased risk of GI neoplasms include slow intestinal transit with a redundant large bowel, altered bile acids, deranged local immune response, shared genetic susceptibility factors and hyperinsulinemia. In view of the increased risk association, most guidelines for the care of acromegaly patients recommend an initial screening colonoscopy. Recommendations for further follow-up colonoscopy differ but broadly, the guidelines agree that it depends on the findings at first colonoscopy and state of remission of GH excess. Regarding the concern about the risk of colorectal cancers in patients receiving recombinant GH therapy, most cohort studies do not show an increased risk.

Effect of metformin on thyroid cancer risk in patients with acromegaly: A preliminary observational study

PURPOSE

To evaluate the role of metformin on thyroid cancer risk in patients with acromegaly.

METHODS

Medical charts of 534 patients with acromegaly that were followed-up between 1983 and 2019 were reviewed. Patients with follow-up duration at least 6 months were included. Cohort entry was defined as first visit date. The date of each case's thyroid cancer diagnosis was defined as index date. Patients were followed until the index date, death, or last visit date, whichever came first. Nested case-control study design was selected to evaluate the association between metformin and the thyroid cancer risk in patients with acromegaly.

RESULTS

291 patients with acromegaly were included into final analysis. The mean age at acromegaly diagnosis was 42.3 ± 1.3 years. The median follow-up duration was 76 [34-132] months. Among 291 patients, 13 patients (4.5%) had thyroid cancer. Thirty-one percent (n = 92) of the patients used metformin for 6 months or longer. One standard deviation (SD) increase in average growth hormone increased the odds of having thyroid cancer by 1.164 folds (p = 0.017). One SD increase of the average insulin-like growth factor 1 to upper limit of normal ratio increased the odds of having thyroid cancer by 1.201 folds (p = 0.004). If a patient used metformin for at least 6 months, the odds to have thyroid cancer was decreased, multiplied by 0.62 with a 95% confidence interval of [0.47, 0.83] (p = 0.0013). The risk of thyroid cancer decreased with increasing duration of metformin use.

CONCLUSION

Metformin may decrease the thyroid cancer risk in patients with acromegaly.

Variables Associated With Body Image Concerns in Acromegaly Patients: A Cross-Sectional Study

Objective

Acromegaly is often characterized by altered physical (including facial) appearance. However, there is little medical or psychological research on body image concerns in patients with acromegaly. The aim of this study was to identify factors influencing the body image distress in patients with acromegaly and to explore the possible effects of stigma on body image concerns.

Design

Cross-sectional study.

Methods

A total of 68 individuals with acromegaly were enrolled in the study. A total of 70 persons with nonfunctional pituitary adenomas were randomly recruited as a healthy control group. Using structured questionnaires, we explored perceived body image using the Body Image Concern Inventory. We also used the Hamilton Anxiety Scale, the Stigma Scale for Chronic Illness, the Brief Illness Perception Questionnaire, and the 36-Item Short-Form Health Survey to evaluate health-associated variables and to analyze factors that affect body image concerns in patients with acromegaly.

Results

Of the 68 participants, 31 were men and 37 women (mean age ± standard deviation: 46.36 ± 12.47 years). The mean body image concern score was 47.49 ± 13.81 for patients with acromegaly and 21.10 ± 7.44 for patients with nonfunctional pituitary adenoma. The difference between the two groups was statistically significant. A multiple stepwise regression analysis showed that the related factors for body image distress were gender (P = 0.001), age at diagnosis (P = 0.01), and internalized stigma (P < 0.001, Adj. R² = 0.756).

Conclusions

People with acromegaly have substantial body image concerns, and these concerns are increased by the stigma associated with this disease; such concerns lead to poor quality of life (QoL). Physicians need to find better ways to control patients' hormone levels, and nurses should provide more information on how to improve body image or find ways to reduce patients' body image distress.

Machine learning as a clinical decision support tool for patients with acromegaly

OBJECTIVE

To develop machine learning (ML) models that predict postoperative remission, remission at last visit, and resistance to somatostatin receptor ligands (SRL) in patients with acromegaly and to determine the clinical features associated with the prognosis.

METHODS

We studied outcomes using the area under the receiver operating characteristics (AUROC) values, which were reported as the performance metric. To determine the importance of each feature and easy interpretation, Shapley Additive explanations (SHAP) values, which help explain the outputs of ML models, are used.

RESULTS

One-hundred fifty-two patients with acromegaly were included in the final analysis. The mean AUROC values resulting from 100 independent replications were 0.728 for postoperative 3 months remission status classification, 0.879 for remission at last visit classification, and 0.753 for SRL resistance status classification. Extreme gradient boosting model demonstrated that preoperative growth hormone (GH) level, age at operation, and preoperative tumor size were the most important predictors for early remission; resistance to SRL and preoperative tumor size represented the most important predictors of remission at last visit, and postoperative 3-month insulin-like growth factor 1 (IGF1) and GH levels (random and nadir) together with the sparsely granulated somatotroph adenoma subtype served as the most important predictors of SRL resistance.

CONCLUSIONS

ML models may serve as valuable tools in the prediction of remission and SRL resistance.

Prevalence and outcome of comorbidities associated with acromegaly

BACKGROUND

Acromegaly is associated with various comorbidities, such as arterial hypertension (aHT), type 2 diabetes mellitus (DM2), obstructive sleep apnoea syndrome (OSAS), carpal tunnel syndrome (CTS) and polyposis coli. For therapeutic decisions, it is essential to know if, and to what extent, these associated morbidities are reversible or preventable. The aim of this study is to assess the prevalence and course of aHT, obesity, OSAS, CTS, DM2 and polyposis coli in acromegalic patients.

METHODS

The following criteria for inclusion in this database study were used: treatment for acromegaly at the authors' institutions; full endocrinological and radiological work- and follow-up; screening for aHT, DM2, CTS, OSAS, obesity and polyposis coli. All patients were followed-up for > 3 months, and treatments were indicated with the intent of biochemical remission (normal IGF-1 and random growth hormone level).

RESULTS

Sixty-three patients were included. Twelve (19%), 45 (71%) and 6 (10%) patients harboured micro-, macro- and giant adenomas, respectively. Nineteen tumours (30%) invaded the cavernous sinus. Mean tumour volume was 5.4 cm³. Mean follow-up time was 42 months. Sixty-one (97%) patients had transsphenoidal surgery; two patients only had drug therapy. Surgery led to remission in 31 (51%) patients. Intracavernous growth and larger tumour volume were negative predictors for cure. Drug therapy lead to remission in 22 (73%) patients within a mean follow-up of 54 months. The pretherapeutic prevalence of associated morbidities was as follows: aHT, 56%; DM2, 25%; OSAS, 29%; CTS, 29%; polyposis coli, 5%. There were neither age nor gender preferences for the respective prevalences. Surgery leads to remission of aHT and DM2 in 6% and 25%, respectively. Additional drug therapy resulted in remission of aHT, DM2 and CTS in 17%, 14% and 14%, respectively. Other associated morbidities persisted regardless of therapeutic efforts. Even if criteria for remission were not met, no new comorbidities of acromegaly developed during follow-up.

CONCLUSIONS

Treating acromegaly may relieve threatening associated morbidities such as aHT and DM2; nevertheless, only few comorbidities are reversible, which highlights the importance of treating acromegaly as early as possible.

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.

Pituitary Adenomas: From Diagnosis to Therapeutics

Pituitary adenomas are tumors that arise in the anterior pituitary gland. They are the third most common cause of central nervous system (CNS) tumors among adults. Most adenomas are benign and exert their effect via excess hormone secretion or mass effect. Clinical presentation of pituitary adenoma varies based on their size and hormone secreted. Here, we review some of the most common types of pituitary adenomas, their clinical presentation, and current diagnostic and therapeutic strategies.

Increased risk of preneoplastic colonic lesions and colorectal carcinoma in acromegaly: multicenter case-control study

PURPOSE

Current international guidelines recommend colonoscopy in patients with acromegaly at the time of diagnosis, even though the risk of developing colorectal neoplasm is still controversial. The main objective of this Argentine multicenter study was to analyze through screening colonoscopy the presence of advanced neoplastic lesions considered as precancerous, in patients with acromegaly compared to a control group.

METHODS

This is a case-control retrospective study. Full length colonoscopy of 70 acromegalic patients and 128 control subjects were studied. Polyps were classified into non pre-cancerous lesions and advance neoplastic lesions which included advanced adenomas (preneoplastic) and colorectal carcinomas.

RESULTS

Thirty three out of 70 acromegalic patients and 32 out of 128 subjects controls presented polyps in the colonoscopy [47.1% vs 25%, p = 0.002, OR 2.68]. Non precancerous polyps were found in 11 (15.7%) and 23 (17.9%) (p = 0.690), while advanced neoplastic lesions were found in 22 (31.4%) and 9 (7.0%) (p = 0,0001 - OR: 6.06) patients and controls respectively. Advanced adenomas and colorectal carcinomas were found in 18 (27.3%) and 9 (7.0%) (p = 0,0006-OR: 4,57), and 4 (5.7%) and 0 (0.0%) p = 0.0063) of patients and controls respectively. The presence of insulin resistance was the only statistically significant associated factor among acromegalic patients with and without colonic polyps.

CONCLUSIONS

Our findings show an increased risk of preneoplastic colonic lesions and colorectal carcinoma in patients with chronic and sustained GH excess compared to a control group. This supports the recommendation to perform screening colonoscopy at diagnosis of acromegaly.

Insulin-like growth factor-1 and site-specific cancers: A Mendelian randomization study

Insulin-like growth factor-1 (IGF-1) is involved in several processes relevant to carcinogenesis. We used 416 single-nucleotide polymorphisms robustly associated with serum IGF-1 levels to assess the potential causal associations between this hormone and site-specific cancers through Mendelian randomization. Summary-level genetic association estimates for prostate, breast, ovarian, and lung cancer were obtained from large-scale consortia including individuals of European-descent. Furthermore, we estimated genetic associations with 14 site-specific cancers in European-descent individuals in UK Biobank. Supplementary analyses were conducted for six site-specific cancers using summary-level data from the BioBank Japan Project. Genetically predicted serum IGF-1 levels were associated with colorectal cancer. The odds ratio (OR) per standard deviation increase of IGF-1 levels was 1.11 (95% confidence interval [CI] 1.01-1.22; P = .03) in UK Biobank and 1.22 (95% CI 1.09-1.36; P = 3.9 × 10-4 ) in the BioBank Japan Project. For prostate cancer, the corresponding OR was 1.10 (95% CI 1.01-1.21; P = .04) in UK Biobank, 1.03 (95% CI 0.97-1.09; P = .41) in the prostate cancer consortium, and 1.08 (95% CI 0.95-1.22; P = .24) in the BioBank Japan Project. For breast cancer, the corresponding OR was 0.99 (95% CI 0.92-1.07; P = .85) in UK Biobank and 1.08 (95% CI 1.02-1.13; P = 4.4 × 10-3 ) in the Breast Cancer Association Consortium. There was no statistically significant association between genetically predicted IGF-1 levels and 14 other cancers. This study found some support for a causal association between elevated serum IGF-1 levels and increased risk of colorectal cancer. There was inconclusive or no evidence of a causal association of IGF-1 levels with prostate, breast, and other cancers.

Upfront Gamma Knife radiosurgery for Cushing’s disease and acromegaly: a multicenter, international study

OBJECTIVE

Gamma Knife radiosurgery (GKS) is typically used after failed resection in patients with Cushing’s disease (CD) and acromegaly. Little is known about the upfront role of GKS for patients with CD and acromegaly. In this study, the authors examine the outcome of upfront GKS for patients with these functioning adenomas.

METHODS

An international group of 7 Gamma Knife centers sent pooled data from 46 patients (21 with CD and 25 with acromegaly) undergoing upfront GKS to the coordinating center of the study for analysis. Diagnosis was established on the basis of clinical, endocrine, and radiological studies. All patients were treated on a common radiosurgical platform and longitudinally followed for tumor control, endocrine remission, and hypopituitarism. Patients received a tumor median margin dose of 25 Gy (range 12–40.0 Gy) at a median isodose of 50%.

RESULTS

The median endocrine follow-up was 69.5 months (range 9–246 months). Endocrine remission was achieved in 51% of the entire cohort, with 28% remission in acromegaly and 81% remission for those with CD at the 5-year interval. Patients with CD achieved remission earlier as compared to those with acromegaly (p = 0.0005). In patients post-GKS, the pituitary adenoma remained stable (39%) or reduced (61%) in size. Hypopituitarism occurred in 9 patients (19.6%), and 1 (2.2%) developed third cranial nerve (CN III) palsy. Eight patients needed further intervention, including repeat GKS in 6 and transsphenoidal surgery in 2.

CONCLUSIONS

Upfront GKS resulted in good tumor control as well as a low rate of adverse radiation effects in the whole group. Patients with CD achieved a faster and far better remission rate after upfront GKS in comparison to patients with acromegaly. GKS can be considered as an upfront treatment in carefully selected patients with CD who are unwilling or unable to undergo resection, but it has a more limited role in acromegaly.

The influence of fasting and energy restricting diets on IGF-1 levels in humans: A systematic review and meta-analysis

BACKGROUND

Fasting and energy restricting diets have a potential means of delaying or preventing the onset of a range of age-related metabolic and neoplastic diseases. Consistently at the centre of this effect appears to be a significant reduction in circulating IGF-1 levels. The aim of the current systematic review and meta-analysis was to determine the influence of fasting and energy restriction on IGF-1 levels in human subjects.

METHODS

A comprehensive systematic search was conducted from onset of the database to February 2019 in Embase, MEDLINE/PubMed, and SCOPUS to identify randomized clinical trials that investigating the impact of fasting or energy restriction circulating IGF-1 levels. Effect size was reported as weighted mean difference (WMD) and 95% confidence intervals (CI) using a random-effects models. Subgroup analysis was performed to identify the probable source of heterogeneity among trials.

RESULTS

Total pooling of fasting and energy restriction randomised controlled trials in WMD analysis revealed no significant effect on circulating IGF-1 levels (WMD: -16.41 ng/ml, 95% CI: -35.88, 3.07). Sub grouped analysis fasting regimens appeared to substantially reduce IGF-1 (WMD: -28.87 ng/ml, 95% CI: -43.69, -14.05, I² = 00%), energy restricting regimens failed to do the same (WMD: -10.98 ng/ml, 95% CI: -33.08, 11.11, I² = 90%). Within this final subgrouping, it was observed that only energy restriction regimens of 50% or greater of normal daily energy intake were capable of significantly reducing IGF-1 levels (WMD: -36.57 ng/ml, 95% CI: -59.19, -13.95, I² = 00%). Finally, a meta regression were noted in which the percentage restriction of daily energy intake inversely correlated with plasma IGF-1 levels (p = 0.04).

CONCLUSION

This study uncovered that fasting significantly reduced levels of IGF-1, while energy restriction diets were successful only when intake was reduced by 50% or more.

DNA damage in obesity: Initiator, promoter and predictor of cancer

Epidemiological evidence linking obesity with increased risk of cancer is steadily growing, although the causative aspects underpinning this association are only partially understood. Obesity leads to a physiological imbalance in the regulation of adipose tissue and its normal functioning, resulting in hyperglycaemia, dyslipidaemia and inflammation. These states promote the generation of oxidative stress, which is exacerbated in obesity by a decline in anti-oxidant defence systems. Oxidative stress can have a marked impact on DNA, producing mutagenic lesions that could prove carcinogenic. Here we review the current evidence for genomic instability, sustained DNA damage and accelerated genome ageing in obesity. We explore the notion of genotoxicity, ensuing from systemic oxidative stress, as a key oncogenic factor in obesity. Finally, we advocate for early, pre-malignant assessment of genome integrity and stability to inform surveillance strategies and interventions.

Screening for comorbid conditions in patients enrolled in the SODA registry: a 2-year observational analysis

PURPOSE

This 2-year analysis assessed frequency of comorbidities and comorbidity screening in the Somatuline^® (lanreotide, LAN) Depot for Acromegaly (SODA) registry.

METHODS

Patient data collected included pituitary hormone deficiencies, sleep studies, echocardiograms, gallbladder sonographies, colonoscopies, and glycated hemoglobin (HbA1c) levels. Insulin-like growth factor-1 (IGF-1) and growth hormone levels in patients with (DM) and without (non-DM) diabetes mellitus were analyzed.

RESULTS

There were 241 patients enrolled. Pituitary hormone deficiencies were reported more frequently at enrollment in male (56.9%) vs female patients (32.0%; p < 0.001). TSH deficiency was the most common endocrine deficiency (69.8%), followed by gonadotropin deficiency (62.3%). Screening tests reported at enrollment: sleep studies in 29.9% (79.2% had sleep apnea), echocardiogram in 46.1% (46.8% abnormal), gallbladder sonography in 18.7% (17.8% had gallstones), and colonoscopy in 48.1% (35.3% had polyps). Follow-up studies were reported less frequently at 1 and 2 years. HbA1c data were reported in 30.8% and 41.2% after 1 and 2 years. HbA1c levels were similar at 1 and 2 years of LAN therapy among DM and non-DM patients with available data. Fewer DM vs non-DM patients achieved IGF-1 below upper limit of normal at Month 24 (58.3% vs 80.6%; p = 0.033).

CONCLUSIONS

Fewer than half of patients in SODA had screening results reported at enrollment for sleep apnea, cardiomyopathy, and colon polyps. Gallbladder imaging was reported in a minority of patients. Lower IGF-1 control rates were observed in DM vs non-DM patients at Month 24. These data suggest a need for better monitoring of comorbidities in US acromegaly patients.

The Growth Hormone Receptor: Mechanism of Receptor Activation, Cell Signaling, and Physiological Aspects

The growth hormone receptor (GHR), although most well known for regulating growth, has many other important biological functions including regulating metabolism and controlling physiological processes related to the hepatobiliary, cardiovascular, renal, gastrointestinal, and reproductive systems. In addition, growth hormone signaling is an important regulator of aging and plays a significant role in cancer development. Growth hormone activates the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling pathway, and recent studies have provided a new understanding of the mechanism of JAK2 activation by growth hormone binding to its receptor. JAK2 activation is required for growth hormone-mediated activation of STAT1, STAT3, and STAT5, and the negative regulation of JAK-STAT signaling comprises an important step in the control of this signaling pathway. The GHR also activates the Src family kinase signaling pathway independent of JAK2. This review covers the molecular mechanisms of GHR activation and signal transduction as well as the physiological consequences of growth hormone signaling.

Regulation of insulin-like growth factor receptors by Ubiquilin1

Insulin-like growth factor-1 receptor (IGF1R) is a receptor tyrosine kinase that mediates growth, proliferation and survival. Dysregulation of IGF pathway contributes to the initiation, progression and metastasis of cancer and is also involved in diseases of glucose metabolism, such as diabetes. We have identified Ubiquilin1 (UBQLN1) as a novel interaction partner of IGF1R, IGF2R and insulin receptor (INSR). UBQLN family of proteins have been studied primarily in the context of protein quality control and in the field of neurodegenerative disorders. Our laboratory discovered a link between UBQLN1 function and tumorigenesis, such that UBQLN1 is lost and underexpressed in 50% of human lung adenocarcinoma cases. We demonstrate here that UBQLN1 regulates the expression and activity of IGF1R. Following loss of UBQLN1 in lung adenocarcinoma cells, there is accelerated loss of IGF1R. Despite decreased levels of total receptors, the ratio of active : total receptors is higher in cells that lack UBQLN1. UBQLN1 also regulates INSR and IGF2R post-stimulation with ligand. We conclude that UBQLN1 is essential for normal regulation of IGF receptors. UBQLN-1-deficient cells demonstrate increased cell viability compared with control when serum-starved and stimulation of IGF pathway in these cells increased their migratory potential by 3-fold. As the IGF pathway is involved in processes of normal growth, development, metabolism and cancer progression, understanding its regulation by Ubiquilin1 can be of tremendous value to many disciplines.

Acromegaly: clinical features at diagnosis

BACKGROUND

Acromegaly is a rare and underdiagnosed disorder caused, in more than 95% of cases, by a growth hormone (GH)-secreting pituitary adenoma. The GH hypersecretion leads to overproduction of insulin-like growth factor 1 (IGF-1) which results in a multisystem disease characterized by somatic overgrowth, multiple comorbidities, physical disfigurement, and increased mortality.

OBJECTIVE

This article aims to review the clinical features of acromegaly at diagnosis.

DISCUSSION/CONCLUSION

Acromegaly affects both males and females equally and the average age at diagnosis ranges from 40 to 50 years (up to 5% of cases < the age 20). Due to insidious onset and slow progression, acromegaly is often diagnosed five to more than ten years after its onset. The typical coarsening of facial features include furrowing of fronthead, pronounced brow protrusion, enlargement of the nose and the ears, thickening of the lips, skin wrinkles and nasolabial folds, as well as mandibular prognathism that leads to dental malocclusion and increased interdental spacing. Excessive growth of hands and feet (predominantly due to soft tissue swelling) is present in the vast majority of acromegalic patients. Gigantism accounts for up to 5% of cases and occurs when the excess of GH becomes manifest in the young, before the epiphyseal fusion. The disease also has rheumatologic, cardiovascular, respiratory, neoplastic, neurological, and metabolic manifestations which negatively impact its prognosis and patients quality of life. Less than 15% of acromegalic patients actively seek medical attention for change in appearance or enlargement of the extremities. The presentation of acromegaly is more often related to its systemic comorbidities or to local tumor effects.

Acromegaly and associated tumours: what should gastroenterologists know?

Acromegaly is a clinical syndrome caused by the excessive production of growth hormone. It is associated with high morbidity and significantly increased mortality, mainly due to cardiovascular and respiratory complications, and cancer. Mortality is reduced to that of the general population following successful treatment, in other words, when insulin-like growth factor (IGF-I) and growth hormone values return to normal levels. Not all tumours associated with this syndrome benefit from cost-effective early diagnosis programmes. An in-depth knowledge on the part of clinicians of the morbidity and mortality associated with acromegaly, allowing them in many cases to anticipate the expected clinical course of the disease, is the best therapeutic and follow-up strategy in these patients.

The risks of overlooking the diagnosis of secreting pituitary adenomas

Secreting pituitary adenomas that cause acromegaly and Cushing’s disease, as well as prolactinomas and thyrotroph adenomas, are uncommon, usually benign, slow-growing tumours. The rarity of these conditions means that their diagnosis is not familiar to most non-specialist physicians. Consequently, pituitary adenomas may be overlooked and remain untreated, and affected individuals may develop serious comorbidities that reduce their quality of life and life expectancy. Because many signs and symptoms of pituitary adenomas overlap with those of other, more common disorders, general practitioners and non-endocrinology specialists need to be aware of the “red flags” suggestive of these conditions. A long duration of active disease in patients with secreting pituitary adenomas is associated with an increased risk of comorbidities and reduced quality of life. Appropriate treatment can lead to disease remission, and, although some symptoms may persist in some patients, treatment usually reduces the incidence and severity of comorbidities and improves quality of life. Therefore, correct, early diagnosis and characterization of a pituitary adenoma is crucial for patients, to trigger timely, appropriate treatment and to optimize outcome. This article provides an overview of the epidemiology of hormonal syndromes associated with pituitary adenomas, discusses the difficulties of and considerations for their diagnosis, and reviews the comorbidities that may develop, but can be prevented, by accurate diagnosis and appropriate treatment. We hope this review will help general practitioners and non-endocrinology specialists to suspect secreting pituitary adenomas and refer patients to an endocrinologist for confirmation of the diagnosis and treatment.

Challenges in the diagnosis and management of acromegaly: a focus on comorbidities

INTRODUCTION

Acromegaly is a rare, insidious disease resulting from the overproduction of growth hormone (GH) and insulin-like growth factor 1 (IGF-1), and is associated with a range of comorbidities. The extent of associated complications and mortality risk is related to length of exposure to the excess GH and IGF-1, thus early diagnosis and treatment is imperative. Unfortunately, acromegaly is often diagnosed late, when patients already have a wide range of comorbidities. The presence of comorbid conditions contributes significantly to patient morbidity/mortality and impaired quality of life.

METHODS

We conducted a retrospective literature review for information relating to the diagnosis of acromegaly, and its associated comorbidities using PubMed. The main aim of this review is to highlight the issues of comorbidities in acromegaly, and to reinforce the importance of early diagnosis and treatment.

FINDINGS AND CONCLUSIONS

Successful management of acromegaly goes beyond treating the disease itself, since many patients are diagnosed late in disease evolution, they present with a range of comorbid conditions, such as cardiovascular disease, diabetes, hypertension, and sleep apnea. It is important that patients are screened carefully at diagnosis (and thereafter), for common associated complications, and that biochemical control does not become the only treatment goal. Mortality and morbidities in acromegaly can be reduced successfully if patients are treated using a multimodal approach with comprehensive comorbidity management.

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.

Effects of 2-year calorie restriction on circulating levels of IGF-1, IGF-binding proteins and cortisol in nonobese men and women: a randomized clinical trial

Young-onset calorie restriction (CR) in rodents decreases serum IGF-1 concentration and increases serum corticosterone levels, which have been hypothesized to play major roles in mediating its anticancer and anti-aging effects. However, little is known on the effects of CR on the IGF-1 system and cortisol in humans. To test the sustained effects of CR on these key hormonal adaptations, we performed a multicenter randomized trial of a 2-year 25% CR intervention in 218 nonobese (body mass index between 22 and 27.8 kg m(-2) ) young and middle-aged (20-50 years age range) men and women. Average CR during the first 6 months was 19.5 ± 0.8% and 9.1 ± 0.7% over the next 18 months of the study. Weight loss averaged 7.6 ± 0.3 kg over the 2-years period of which 71% was fat mass loss (P < 0.0001). Average CR during the CR caused a significant 21% increase in serum IGFBP-1 and a 42% reduction in IGF-1:IGFBP-1 ratio at 2 years (P < 0.008), but did not change IGF-1 and IGF-1:IGFBP-3 ratio levels. Serum cortisol concentrations were slightly but significantly increased by CR at 1 year only (P = 0.003). Calorie restriction had no effect on serum concentrations of PDGF-AB and TGFβ-1. We conclude, on the basis of the present and previous findings, that, in contrast to rodents, humans do not respond to CR with a decrease in serum IGF-1 concentration or with a sustained and biological relevant increase in serum cortisol. However, long-term CR in humans significantly and persistently increases serum IGFBP-1 concentration.

Obesity and Colorectal Cancer

There is strong evidence that modifiable lifestyle factors such as obesity play a key role in colorectal carcinogenesis. Epidemiologic data have consistently reported a positive association between obesity and colorectal cancer. The relative risk associated with general obesity (as assessed by BMI) is higher in men than in women and for cancer of the colon than for cancer of the rectum. Abdominal obesity (as assessed by waist circumference (WC) or waist-to-hip ratio) is associated with an increased risk of colorectal cancer in both sexes, with stronger associations for cancer of the colon than for cancer of the rectum. Plausible biological mechanisms include insulin resistance, hyperinsulinemia, chronic inflammation, altered levels of growth factors, adipocytokines and steroid hormones. In addition to its effect on colorectal cancer incidence, obesity may play a role in colorectal cancer recurrence, treatment outcomes and survival. Understanding the effects of childhood and adolescent obesity and weight change over the life course in relation to future risk of colorectal cancer is incomplete but essential for targeted preventive recommendations. This chapter summarizes the current evidence on the relationship between obesity and colorectal cancer and colorectal adenoma, a common precursor lesion.

60 YEARS OF NEUROENDOCRINOLOGY: Acromegaly

Acromegaly (ACM) is a chronic, progressive disorder caused by the persistent hypersecretion of GH, in the vast majority of cases secreted by a pituitary adenoma. The consequent increase in IGF1 (a GH-induced liver protein) is responsible for most clinical features and for the systemic complications associated with increased mortality. The clinical diagnosis, based on symptoms related to GH excess or the presence of a pituitary mass, is often delayed many years because of the slow progression of the disease. Initial testing relies on measuring the serum IGF1 concentration. The oral glucose tolerance test with concomitant GH measurement is the gold-standard diagnostic test. The therapeutic options for ACM are surgery, medical treatment, and radiotherapy (RT). The outcome of surgery is very good for microadenomas (80-90% cure rate), but at least half of the macroadenomas (most frequently encountered in ACM patients) are not cured surgically. Somatostatin analogs are mainly indicated after surgical failure. Currently their routine use as primary therapy is not recommended. Dopamine agonists are useful in a minority of cases. Pegvisomant is indicated for patients refractory to surgery and other medical treatments. RT is employed sparingly, in cases of persistent disease activity despite other treatments, due to its long-term side effects. With complex, combined treatment, at least three-quarters of the cases are controlled according to current criteria. With proper control of the disease, the specific complications are partially improved and the mortality rate is close to that of the background population.

Insulin-like growth factor receptor-1 overexpression is associated with poor response of rectal cancers to radiotherapy

AIM: To explore the potential correlation between insulin-like growth factor receptor-1 (IGF-1R) expression and rectal cancer radiosensitivity.

METHODS: Eighty-seven rectal cancer patients (cTNM I-III) treated in our department between January 2011 and December 2012 were enrolled. All subjects were treated with preoperative radiotherapy and radical resection of rectal carcinoma. Immunohistochemistry and reverse transcription polymerase chain reaction (RT-PCR) were performed to detect IGF-1R expression in pre-treatment and postoperative colorectal cancer specimens. Radiosensitivity for rectal cancer specimens was evaluated by observing rectal carcinoma mass regression combined with fibrosis on HE staining, degree of necrosis and quantity of remaining tumor cells. The relative IGF-1R expression was evaluated for association with tumor radiosensitivity.

RESULTS: Immunohistochemistry showed diffuse IGF-1R staining on rectal cancer cells with various degrees of signal density. IGF-1R expression was significantly correlated with cTNM staging (P = 0.012) while no significant association was observed with age, sex, tumor size and degree of differentiation (P = 0.424, 0.969, 0.604, 0.642). According to the Rectal Cancer Regression Grades (RCRG), there were 31 cases of RCRG1 (radiation sensitive), 28 cases of RCRG2 and 28 cases of RCRG3 (radiation resistance) in 87 rectal cancer subjects. IGF-1R protein hyper-expression was significantly correlated with a poor response to radiotherapy (P < 0.001, r = 0.401). RT-PCR results from pre-radiation biopsy specimens also showed that IGF-1R mRNA negative group exhibited a higher radiation sensitivity (P < 0.001, r = 0.497). Compared with the pre-radiation biopsy specimens, the paired post-operative specimens showed a significantly increased IGF-1R protein and mRNA expression in the residual cancer cells (P < 0.001, respectively).

CONCLUSION: IGF-1R expression level may serve as a predictive biomarker for radiosensitivity of rectal cancer before preoperative radiotherapy.

GH therapy and cancer risk in hypopituitarism: what we know from human studies

It has been difficult to identify factors that affect the risk of cancer, but we know that people are at higher risk as they get older, or if they have a strong family history of cancer. The potential influence of environmental and behavioral factors remains poorly understood. Early population-based and case-control studies suggested that higher serum levels of IGF1 could be associated with increased cancer risk. Since GH therapy increases IGF1 levels, concern has been raised regarding its potential role as a cancer initiation factor. Experimental evidence and some clinical studies showed that when GH/IGF1 secretion or action was inhibited, a decreased incidence and rate of progression of cancers occurred. However, human populations comprise a garden variety of genotypes that respond differently to the same kind of exposures. Human population studies frequently reveal only very small effects to these exposures. So, are GH and cancer guilty by association? After more than 20 years, leukemia, a major safety issue initially believed associated with GH treatment in children with GH deficiency (GHD), has not been confirmed but the risk of second malignancies in patients previously treated with irradiation has been detected or confirmed through the National Cooperative Growth Study. Overall, this large study confirmed the favorable overall safety profile of GH therapy in children with GHD, and also highlighted specific populations at potential risk. The risk of secondary malignancy following radiotherapy is surely related to radiotherapy more than GH therapy that may increase growth but is less likely to start the oncogenic process. In GH-deficient adults treated with GH, observational studies (KIMS, HypoCCS) have shown that when IGF1 levels were targeted within normal age-related reference ranges, the occurrence of malignancies was not higher than in the general population.

Acromegaly: a single centre's experience of stereotactic radiosurgery and radiotherapy for growth hormone secreting pituitary tumours with the linear accelerator

Primary treatment for growth-hormone secreting pituitary adenomas usually involves surgery, with treatment options for recurrent and persistent disease including repeat surgery, medication and radiation therapy. The majority of previously published series for radiation therapy in acromegaly in the past 20 years have been based on Gamma-Knife (Elekta, Stockholm, Sweden) surgery. To our knowledge, we present the largest series of linear accelerator-based treatment for this disease, with a review of 121 patients treated at our institution; since 1990, 86 patients underwent stereotactic radiosurgery (SRS), 10 patients underwent fractionated stereotactic radiotherapy (FSRT), and for the purposes of comparison we also reviewed 25 patients who underwent conventional radiotherapy prior to 1990. Tumour volume control in all three groups was excellent and consistent with previously reported literature - only three of 86 (4%) patients undergoing SRS had a documented increase in tumour size, and none of the patients undergoing FSRT had a documented increase in size following a median follow-up of 5.5 and 5.1 years for SRS and FSRT, respectively. Target growth hormone levels of <2.5 ng/mL were met by 12 of 86 (14%) of the SRS group, and by two of 10 (20%) in the FSRT group. Target insulin-like growth factor-1 levels of age and sex matched controls were achieved in 16 of 86 patients (18.6%) post-SRS and five of 10 patients (50%) post-FSRT. New hormonal deficits requiring replacement therapy were identified in 17 of 86 (19.8%) patients post-SRS which is consistent with previously published radiosurgical series. Identified non-hormonal morbidity was low (<5%).

Micronucleus evaluation in mitogen-stimulated lymphocytes of patients with acromegaly

Acromegaly is a syndrome characterized by a sustained elevation of circulating growth hormone and insulin-like growth factor-1 (IGF-1). Insulin-like growth factor-1 is a potent mitogen and has a role in the transformation of normal cells to malignant cells. This study aims to evaluate the spontaneous micronucleus (MN) frequency by using the cytokinesis-block MN assay to determine genetic damage in the lymphocytes of patients with acromegaly. The study was carried out in 20 patients who had active acromegaly and in 20 age- and sex-matched healthy controls. The MN values were measured in binucleated cells obtained from mitogen-stimulated lymphocytes of patients and control subjects. The distribution of binucleated cells with 1, 2, 3, or more MNs was also measured. We found significantly higher MN frequency values in the lymphocytes of acromegalic patients than in those of the control subjects (2.23 ± 0.68 vs 1.03 ± 0.54, P = .001). The MN frequency increased with increasing IGF-1 levels of acromegalic patients (P = .036, R = 0.47). We observed that the number of binucleated cells with 2 MNs was higher for the majority of patients with acromegaly than for control subjects. Furthermore, the receiver operating characteristic curve (area under the curve = 0.914, P < .0001) was calculated to assess the discriminative power of the MN frequency. Our results indicate that increased MN frequency in the lymphocytes of patients with acromegaly may reflect genomic instability and this increased MN frequency may be associated with elevated levels of circulating growth hormone and IGF-1.

Growth hormone, the insulin-like growth factor axis, insulin and cancer risk

Growth hormone (GH), insulin-like growth factor (IGF)-I and insulin have potent growth-promoting and anabolic actions. Their potential involvement in tumor promotion and progression has been of concern for several decades. The evidence that GH, IGF-I and insulin can promote and contribute to cancer progression comes from various sources, including transgenic and knockout mouse models and animal and human cell lines derived from cancers. Assessments of the GH-IGF axis in healthy individuals followed up to assess cancer incidence provide direct evidence of this risk; raised IGF-I levels in blood are associated with a slightly increased risk of some cancers. Studies of human diseases characterized by excess growth factor secretion or treated with growth factors have produced reassuring data, with no notable increases in de novo cancers in children treated with GH. Although follow-up for the vast majority of these children does not yet extend beyond young adulthood, a slight increase in cancers in those with long-standing excess GH secretion (as seen in patients with acromegaly) and no overall increase in cancer with insulin treatment, have been observed. Nevertheless, long-term surveillance for cancer incidence in all populations exposed to increased levels of GH is vitally important.

Body size, IGF and growth hormone polymorphisms, and colorectal adenomas and hyperplastic polyps

OBJECTIVE

We examined the risk of colorectal polyps in relation to body size factors and candidate polymorphisms in selected genes of insulin-like growth factor (IGF1) (rs5742612), IGF1 receptor (IGF1R) (rs2229765), IGF binding protein 3 (IGFBP3) (rs2854746) and growth hormone (GH1) (rs2665802).

DESIGN

Cases with colorectal adenomas (n=519), hyperplastic polyps (n=691), or both lesions (n=227), and controls (n=772), aged 20-74 years, were recruited from patients who underwent colonoscopy between December 2004 and September 2007 at a large integrated-health plan in Washington state. Subjects participated in a 45-minute telephone interview to ascertain body size and physical activity, and provided a buccal DNA sample for genetic analysis. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using multivariable polytomous regression.

RESULTS

Compared to those of normal weight, higher body mass index (BMI) was associated with elevated risk of colorectal adenomas (OR=1.65, 95% CI 1.22-2.25 BMI>or=30 kg/m(2), p-trend=0.002) and both lesions (OR=2.15, 95% CI 1.43-3.22 BMI>or=30 kg/m(2), p-trend=0.003), but there was no relationship with hyperplastic polyps. Obesity at age 18 and a weight gain of >or=21 kg since age 18 were also significantly associated with an increased risk of colorectal adenomas and both lesions, but not hyperplastic polyps. There was a reduced risk of colorectal adenomas (OR=0.63, 95% CI 0.42-0.94) and hyperplastic polyps (OR=0.7, 95% CI 0.5-0.9) associated with the homozygous variant genotype for GH1. Few meaningful results were evident for the other polymorphisms.

CONCLUSIONS

There is an increased risk of colorectal adenomas and presence of both adenomas and hyperplastic polyps in relation to increasing body size. Some genetic variation in GH1 might contribute to a reduced risk of colorectal adenomas and hyperplastic polyps.

Mortality in patients with pituitary disease

Pituitary disease is associated with increased mortality predominantly due to vascular disease. Control of cortisol secretion and GH hypersecretion (and cardiovascular risk factor reduction) is key in the reduction of mortality in patients with Cushing's disease and acromegaly, retrospectively. For patients with acromegaly, the role of IGF-I is less clear-cut. Confounding pituitary hormone deficiencies such as gonadotropins and particularly ACTH deficiency (with higher doses of hydrocortisone replacement) may have a detrimental effect on outcome in patients with pituitary disease. Pituitary radiotherapy is a further factor that has been associated with increased mortality (particularly cerebrovascular). Although standardized mortality ratios in pituitary disease are falling due to improved treatment, mortality for many conditions are still elevated above that of the general population, and therefore further measures are needed. Craniopharyngioma patients have a particularly increased risk of mortality as a result of the tumor itself and treatment to control tumor growth; this is a key area for future research in order to optimize the outcome for these patients.

Performance of computed tomographic colonography for the screening of colorectal polyp in acromegalic patients: a prospective study

CONTEXT

Acromegalic patients have better chances to develop colorectal polyps and cancer and, considered a high-risk group, need to undergo frequent screening examinations. Moreover, in acromegalia, the increased bowel length and the intestinal loop complexity can lead to higher levels of technical difficulties and increase the risks of complications at conventional colonoscopy. Computed tomographic colonography, also known as virtual colonoscopy, is an innovative and secure technology which is revolutionizing the diagnosis of colon and rectum neoplasias.

OBJECTIVE

To analyze computed tomographic colonography performance for the screening of colorectal polyps in acromegalic patients.

METHODS

A prospective study of 21 asymptomatic acromegalic patients, 12 male and 9 female, average age 49, who underwent computed tomographic colonography and conventional colonoscopy. Computed tomographic colonography was performed with a GE Helical Multislice Computed Tomography Apparatus. Conventional colonoscopy was performed in the same day, without previous knowledge of the computed tomographic colonography diagnostics. The study evaluated the capacity of computed tomographic colonography to detect patients with colorectal polyps and identify each colorectal lesion described by the colonoscopy.

RESULTS

In two patients (2/21), conventional colonoscopy was incomplete. However, in all patients computed tomographic colonography was complete. In Phase I ('per patient'), computed tomographic colonography diagnosed eight of the nine patients with colorectal polyps and showed 88% sensitivity, 75% specificity and 81% accuracy. In Phase II ('per polyp'), out of the 21 acromegalic patients included in this study, 12 presented normal findings at conventional colonoscopy. A total of 19 polyps were identified in 9 patients. Ten of the 19 polyps were smaller than 10 mm, and 9 were equal to or larger than 10 mm. Computed tomographic colonography identified 7 of the 9 polyps >10 mm described by conventional colonoscopy and only 6 of the 10 small polyps identified at conventional colonoscopy were detected by computed tomographic colonography. The histological analysis of resected lesions revealed 12 tubular adenomas, 6 hyperplastic polyps and 1 colonic tubulo-villous adenoma with an adenocarcinoma focus.

CONCLUSION

The authors present the first reports of computed tomographic colonography in the screening of colorectal polyps in acromegalic patients. In this study, computed tomographic colonography was performed without complications and a complete and safe colorectal evaluation was possible in all acromegalic patients. Moreover, computed tomographic colonography presented good sensitivity, specificity and accuracy for the identification of acromegalic patients with polyps of any size and better results in the diagnosis of large polyps, when they were compared to small polypoid lesions.

Pituitary tumours: acromegaly

Excessive production of the growth hormone (GH) is responsible for acromegaly. It is related to a pituitary GH-secreting adenoma in most cases. Prevalence is estimated 40-130 per million inhabitants. It is characterised by slowly progressive acquired somatic disfigurement (mainly involving the face and extremities) and systemic manifestations. The rheumatologic, cardiovascular, respiratory and metabolic consequences determine its prognosis. The diagnosis is confirmed by an increased serum GH concentration, unsuppressible by an oral glucose load and by detection of increased levels of insulin-like growth factor-I (IGF-I). Treatment is aimed at correcting (or preventing) tumour compression by excising the disease-causing lesion, and at reducing GH and IGF-I levels to normal values. When surgery, the usual first-line treatment, fails to correct GH/IGF-I hypersecretion, medical treatment with somatostatin analogues and/or radiotherapy can be used. The GH-receptor antagonist (pegvisomant) is helpful in patients who are resistant to somatostatin analogues. Thanks to this multistep therapeutic strategy, adequate hormonal disease control is achieved in most cases, allowing a normal life expectancy.

Reduced colonic apoptosis in mice overexpressing bovine growth hormone occurs through changes in several kinase pathways

OBJECTIVE

Growth hormone (GH) has antiapoptotic effects in several cell lines, including human colonic adenocarcinoma cells. In addition, it has been reported that patients with acromegaly have reduced apoptosis in colonic mucosa. The aim of the study was to investigate colonic apoptosis and underlying molecular mechanisms in transgenic mice overexpressing bovine GH (Acro) aged 3 months (young) or 9 months (elder).

DESIGN AND METHODS

Apoptosis in colonic epithelial cells was evaluated by TUNEL and Annexin V; expression of pro- and anti-apoptotic proteins was assessed by Western blot. GH action was blocked treating Acro with a selective GH receptor antagonist.

RESULTS

Young and elder Acro had lower colonic apoptosis [driven by GH through p38, p44/42 and PI3 kinase pathways], than littermate controls; changes were abolished by treating Acro with a selective GH receptor antagonist. The effects of GH were consistent with an anti-apoptotic phenotype (reduced cytosolic cytochrome-c, Bad and Bax and increased Bcl-2, and Bcl-XL level) leading to lower activation of caspase-9 and caspase-3. Changes in apoptotic proteins reversed after treatment with a GH receptor antagonist, suggesting a direct effect of GH. In addition, antiapoptotic phenotype of Acro had a protective role against doxorubicin-induced apoptosis.

CONCLUSIONS

Our results suggest that GH leads to increased and reduced levels of anti- and pro-apoptotic proteins, respectively, lowering apoptosis in either young or elder transgenic animals through activation of several kinase pathways.

Detection of small bowel tumors by videocapsule endoscopy in patients with acromegaly

The prevalence of colon polyposis andmalignancies is increased in acromegalic patients as compared to the general population. An epidemiological study suggests a high prevalence also of small bowel (SB) tumors that nowadays may be detected by videocapsule endoscopy (VCE). The aim of the study was to assess the prevalence of SB neoplasms using VCE in acromegalic patients in comparison to control subjects and to correlate it with cancer risk factors and acromegaly-related parameters. Eighteen acromegalic patients (6 males and 12 females, age+/-SD: 54+/-10 yr), 5 cured after surgery (followed by radiotherapy in 3 cases) and 13 on pharmacological treatment were enrolled, and 36 sex- and age-matched non-acromegalic subjects served as a control group. Cancer risk factors, duration of acromegaly, GH and IGF-I levels, IGF binding protein 3 and IGF-II concentrations, metabolic parameters, tumor markers, colonic lesions by total colonoscopy, and SB lesions by VCE were investigated. VCE images suggestive of SB lesions were detected in 5/36 controls [14%, 4 described as gastrointestinal stromal nodular tumors (GIST), and 1 as polyp] and in 5/18 acromegalic patients [28%, 2 GIST and 3 polyps]. In acromegaly, the calculated relative risk for all SB lesions was 1.69 [95%confidence interval (CI): 0.78-3.65], while the relative risk for SB polyps was 2.50 (95% CI: 1.23-5.07). The effective duration of active disease was longer in patients with positive than in those with negative VCE (112+/-89 vs 49+/-40 months, p=0.06). In conclusion, these preliminary results suggest that acromegalic patients might have a high risk of SB polyp development. VCE might be a useful adjunctive diagnostic tool in acromegaly.

Customizing the targeting of IGF-1 receptor

The type 1 IGF receptor (IGF-IR) is activated by two ligands, IGF-1 and IGF-2, and by insulin at supraphysiological concentrations. It plays a significant role in the growth of normal and abnormal cells, and antibodies against the IGF-IR are now in clinical trials. Targeting of the IGF-IR in cancer cells (by antibodies or other means) can be improved by the appropriate selection of responsive tumors. This review focuses on the optimization of IGF-IR targeting in human cancer.

Function of CSE1L/CAS in the secretion of HT-29 human colorectal cells and its expression in human colon

The secretion of colorectal epithelium is important for maintaining the physiological function of colorectal organ. Herein, we report that cellular apoptosis susceptibility (CAS) (or CSE1L) protein regulates the secretion of HT-29 human colorectal cells. Polarity is essential for directed secretion of substances produced by epithelial cells to the external (luminal) compartment; CAS overexpression induced polarization of HT-29 cells. CAS was punctate stained in the cytoplasm of HT-29 cells, and CAS overexpression increased the translocation of CAS-stained vesicles to the cytoplasm near cell membrane and cell protrusions. CAS overexpression increased the secretion of carcinoembryonic antigen (CEA) and cathepsin D. Immunohistochemistry showed CAS was positively stained in the goblet cells of colon mucosa and cells in the crypts of Lieberkühn of human colon as well as the glands in metastatic colorectal cancer tissue. Our results suggest that CAS regulates the secretion of colorectal cells and may regulate the metastasis of colorectal cancer.

Recreational physical activity modifies the association between a common GH1 polymorphism and colorectal cancer risk

Growth hormone may be associated with the development of colorectal cancer directly and/or indirectly via increased serum level of insulin-like growth factor (IGF-I). Regular physical activity can decrease insulin resistance and modulates IGF-I production. A common polymorphism in the GH1 gene, rs2665802, was previously shown to be associated with lower IGF-I levels and decreased colorectal cancer (CRC) risk. We investigated the association of this polymorphism and physical activity with colorectal cancer risk in a case-control study.

METHODS

The analysis includes 3,041 (1,402 cases and 1,639 controls) participants in the Molecular Epidemiology of Colorectal Cancer study, a population-based case-control study in Northern Israel. Analysis was carried out separately in two sets. The first set included 1,248 subjects (625 cases, 623 controls), and the second validation set consisted of 1,793 subjects (777 cases, 1,016 controls).

RESULTS

No association was found between the studied polymorphism and CRC risk. However, evaluation of gene environment interactions revealed an interaction between leisure time physical activity and the GH1 polymorphism, which was consistent in both sets (P(interaction) = 0.005). The genotype AA was associated with decreased risk of CRC among individuals who did not engage in any such activity (odds ratio, 0.76; 95% confidence interval, 0.52-0.98), whereas the same genotype was marginally associated with increased risk among individuals who reported physical activity (odds ratio, 1.38; 95% confidence interval, 0.98-1.94).

CONCLUSIONS

We found that the A allele of the rs2665802 polymorphism is associated with reduced risk of CRC only among physically inactive individuals, indicating an interaction between physical activity and the growth hormone/IGF-I system. A replication of the observed findings and further investigation of the underlying mechanism is warranted.

Computed tomography colonography in acromegaly

INTRODUCTION AND AIM

Acromegalic patients have an increased risk for the development of colorectal cancer. For this reason, since 1996, screening colonoscopy has been recommended in all patients with acromegaly. The aim of our study was to assess the feasibility and to evaluate the results of computed tomography (CT)-colonography in acromegaly.

PATIENTS AND METHODS

We examined 23 acromegalic patients with no history of colorectal cancer (11 females and 12 males; age range 18-79 yr; disease duration range 1-15 yr) with CT-colonography. Twenty of them underwent traditional colonoscopy after the CT-colonography.

RESULTS

CT-colonography examination results were adequate in 17 of 23 cases (73%). CT-colonography found 12 polyps in eight patients, 95% confirmed by traditional colonoscopy. One polyp was a sigmoid cancer, and the diagnosis was confirmed at surgery. There were no polyps found by traditional colonoscopy that CT-colonography was not able to identify. The lesions were located in right colon (two), transversum (three), left colon (five), and sigmoid colon (two). Patient acceptance of the technique was good in 65%, medium in 20%, and poor in 15%.

CONCLUSION

For the first time we have demonstrated that CT-colonography has the potential ability to replace traditional colonoscopy in acromegalic patients. CT-colonography could be used as a screening modality for colon cancer in acromegaly.

Growth hormone excess and the development of growth hormone receptor antagonists

In 1990, a single amino acid substitution in the growth hormone (GH) gene at position 119 was found to transform the consequent protein from an agonist to an antagonist at the growth hormone receptor (GHR). Further amino acid substitutions plus prolongation of the half-life of the protein by pegylation resulted in the first clinically effective GHR antagonist, pegvisomant. Following extensive clinical trials, this medication has emerged as the most efficacious therapy for treatment-resistant acromegaly. Subsequent advances in our understanding of GH-GHR interactions and downstream GH signalling pathways suggest that pegvisomant binds to preformed GHR dimers and prevents rotational changes within the receptor-GH complex necessary for intracellular signalling to occur. This article reviews the discovery of pegvisomant, from initial experimental data to successful licensing of the drug for treatment-resistant acromegaly, and discusses its other potential therapeutic uses in diseases with abnormalities in the GH-IGF-I axis.

Acromegaly

Acromegaly is an acquired disorder related to excessive production of growth hormone (GH) and characterized by progressive somatic disfigurement (mainly involving the face and extremities) and systemic manifestations. The prevalence is estimated at 1:140,000-250,000. It is most often diagnosed in middle-aged adults (average age 40 years, men and women equally affected). Due to insidious onset and slow progression, acromegaly is often diagnosed four to more than ten years after its onset. The main clinical features are broadened extremities (hands and feet), widened thickened and stubby fingers, and thickened soft tissue. The facial aspect is characteristic and includes a widened and thickened nose, prominent cheekbones, forehead bulges, thick lips and marked facial lines. The forehead and overlying skin is thickened, sometimes leading to frontal bossing. There is a tendency towards mandibular overgrowth with prognathism, maxillary widening, tooth separation and jaw malocclusion. The disease also has rheumatologic, cardiovascular, respiratory and metabolic consequences which determine its prognosis. In the majority of cases, acromegaly is related to a pituitary adenoma, either purely GH-secreting (60%) or mixed. In very rare cases, acromegaly is due to ectopic secretion of growth-hormone-releasing hormone (GHRH) responsible for pituitary hyperplasia. The clinical diagnosis is confirmed biochemically by an increased serum GH concentration following an oral glucose tolerance test (OGTT) and by detection of increased levels of insulin-like growth factor-I (IGF-I). Assessment of tumor volume and extension is based on imaging studies. Echocardiography and sleep apnea testing are used to determine the clinical impact of acromegaly. Treatment is aimed at correcting (or preventing) tumor compression by excising the disease-causing lesion, and at reducing GH and IGF-I levels to normal values. Transsphenoidal surgery is often the first-line treatment. When surgery fails to correct GH/IGF-I hypersecretion, medical treatment with somatostatin analogs and/or radiotherapy can be used. The GH antagonist (pegvisomant) is used in patients that are resistant to somatostatin analogs. Adequate hormonal disease control is achieved in most cases, allowing a life expectancy similar to that of the general population. However, even if patients are cured or well-controlled, sequelae (joint pain, deformities and altered quality of life) often remain.

Does acromegaly enhance mortality?

The increased mortality associated with acromegaly was first demonstrated in early epidemiological studies. Since the seminal paper by Wright et al. in 1970, nearly 20 studies have analyzed mortality rates in over 5,000 patients with acromegaly. Overall standardized mortality rates are approximately two times higher than in the general population, relating to an average reduction in life expectancy of around 10 years. The excess deaths are due predominantly to cardiovascular, cerebrovascular and respiratory disease. Malignancy deaths have been high in some studies but not others; in the largest series looking at cancer mortality in acromegaly, overall cancer deaths were not increased, but colon cancer mortality was higher than expected. In 1993, Bates et al. first demonstrated that outcome was related to the latest measurable growth hormone (GH), and treatment to reduce GH levels led to improved outcomes. Other factors predicting poor outcome include the presence of hypertension and diabetes. On the basis of current evidence, a latest GH of less than 2-2.5 mug/L is a better predictor of good outcome than a normal insulin-like growth factor-1 (IGF-1), possibly due to discrepancy between GH and IGF-1 at low GH levels. There is some evidence to suggest a more stringent GH cut-off (less than 1 mug/L) may yield additional benefit but further studies are required to investigate any added risk of increased mortality from hypopituitarism. Radiotherapy has been linked specifically to cerebrovascular mortality and its use in patients with acromegaly must involve a careful risk-benefit analysis in each case.