IGFs and human cancer: implications regarding the risk of growth hormone therapy

Somatopause, weaknesses of the therapeutic approaches and the cautious optimism based on experimental ageing studies with soy isoflavones

The pathological phenomenon of somatopause, noticeable in hypogonadal ageing subjects, is based on the growth hormone (GH) production and secretion decrease along with the fall in GH binding protein and insulin-like growth factor 1 (IGF-1) levels, causing different musculoskeletal, metabolic and mental issues. From the perspective of safety and efficacy, GH treatment is considered to be highly controversial, while some other therapeutic approaches (application of IGF-1, GH secretagogues, gonadal steroids, cholinesterase-inhibitors or various combinations) exhibit more or less pronounced weaknesses in this respect. Soy isoflavones, phytochemicals that have already demonstrated the health benefits in treated elderly, at least experimentally reveal their potential for the somatopausal symptoms remediation. Namely, genistein enhanced GHRH-stimulated cAMP accumulation and GH release in rat anterior pituitary cells; refreshed and stimulated the somatotropic system (hypothalamic nuclei and pituitary GH cells) function in a rat model of the mild andropause, and stimulated the GH output in ovariectomized ewes as well as the amplitude of GH pulses in the rams. Daidzein, on the other hand, increased body mass, trabecular bone mass and decreased bone turnover in the animal model of severe andropause, while both isoflavones demonstrated blood cholesterol-lowering effect in the same model. These data, which necessarily need to be preclinically and clinically filtered, hint some cautious optimism and call for further innovative designing of balanced soy isoflavone-based therapeutics.

Role of breast cancer inhibitors on diabetes mellitus- an in silico approach

Background

Breast cancer and diabetes mellitus type-2 are two of the major diseases, which cause death to the women worldwide. Around 16% of the breast cancer patients also suffer from diabetes mellitus. It has been noted that the risk of occurrence of the breast cancer is more in patients suffering from diabetes mellitus.

Methods

Owing to this, the present article deals with an objective of using the breast cancer inhibitors for the diabetes drug target– 1ADS. Ten breast cancer inhibitors were drawn using Marvin Sketch. The docking was performed using Molegro software (Molegro Virtual Docker, MVD).

Results

The docking wizard generated 50 poses with the highest Mol Dock score −131.649.

Conclusion

This investigation successfully evaluated the effect of breast cancer inhibitors on diabetes mellitus, providing a new dimension in endocrine research.

Adult growth hormone deficiency - benefits, side effects, and risks of growth hormone replacement

Deficiency of growth hormone (GH) in adults results in a syndrome characterized by decreased muscle mass and exercise capacity, increased visceral fat, impaired quality of life, unfavorable alterations in lipid profile and markers of cardiovascular risk, decrease in bone mass and integrity, and increased mortality. When dosed appropriately, GH replacement therapy (GHRT) is well tolerated, with a low incidence of side effects, and improves most of the alterations observed in GH deficiency (GHD); beneficial effects on mortality, cardiovascular events, and fracture rates, however, remain to be conclusively demonstrated. The potential of GH to act as a mitogen has resulted in concern over the possibility of increased de novo tumors or recurrence of pre-existing malignancies in individuals treated with GH. Though studies of adults who received GHRT in childhood have produced conflicting reports in this regard, long-term surveillance of adult GHRT has not demonstrated increased cancer risk or mortality.

Combined evaluation of IGF-1 and IGFBP-3 as an index of efficacy and safety in growth hormone treated patients

OBJECTIVE

Measurement of serum insulin-like growth factor-1 (IGF-1) and IGF binding protein-3 (IGFBP-3) levels has been recommended as a useful index for monitoring of growth hormone (GH) therapy in GH deficient children. In this study we aimed to evaluate IGF-1/IGFBP-3 molar ratio during GH treatment as an index of safety and efficacy.

METHODS

Serum IGF-1 and IGFBP-3 levels and molar ratio of IGF-1/IGFBP-3 were evaluated in 50 GH deficienct children, during 3 years of GH therapy and these parameters were compared with the growth response.

RESULTS

All patients completed the first year, 38 the second year and 26 the third year of therapy. Although 15 patients in the first year, 5 patients in the second year, and 5 patients in the third year had high IGF-1 SDS values, height increments were similar in the low IGF-1 group and in the normal or high IGF-1 level groups. Molar ratios were also not statistically different between the groups. Molar ratio of IGF-1/IGFBP-3 seemed to be more reliable in evaluating the efficacy than basal IGF-1 level.

CONCLUSIONS

Evaluation of the molar ratio of IGF-1/IGFBP-3 may be recommended as a tool to monitor GH treatment and it may be possible to individualize GH treatment accordingly.

Lycopene differentially induces quiescence and apoptosis in androgen-responsive and -independent prostate cancer cell lines

BACKGROUND & AIMS

Lycopene has been credited with a number of health benefits including a decrease in prostate cancer risk. Our study investigates the molecular mechanism underlying anti-cancer activity of lycopene-based products in androgen-responsive (LNCaP) and androgen-independent (PC3) cells.

METHODS

The effect of lycopene-based agents on prostate cancer growth and survival were examined using proliferation assays, bromodeoxyuridine incorporation and flow cytometric analysis of cellular DNA content. Biochemical effects of lycopene treatment were investigated by immunoblotting for changes in the absolute levels and phosphorylation states of cell cycle regulatory and signalling proteins.

RESULTS

LNCaP and PC3 cells treated with the lycopene-based agents undergo mitotic arrest, accumulating in G0/G1 phase. Immunoblot screening indicated that lycopene's antiproliferative effects are likely achieved through a block in G1/S transition mediated by decreased levels of cyclins D1 and E and cyclin dependent kinase 4 and suppressed Retinoblastoma phosphorylation. These responses correlated with decreased insulin-like growth factor-I receptor expression and activation, increased insulin-like growth factor binding protein 2 expression and decreased AKT activation. Exposure to lycopene at doses as low as 10 nM for 48 h induced a profound apoptotic response in LNCaP cells. In contrast PC3 cells were resistant to apoptosis at doses up to 1 microM.

CONCLUSIONS

Lycopene exposure can suppress phosphatidylinositol 3-kinase-dependent proliferative and survival signalling in androgen-responsive LNCaP and androgen-independent PC3 cells suggesting that the molecular mechanisms for the cytostatic and cytotoxic actions of lycopene involve induction of G0/G1 cell cycle arrest. This study supports further examination of lycopene as a potential agent for both the prevention and treatment of prostate cancer.

1alpha,25-Dihydroxyvitamin D and fish oil synergistically inhibit G1/S-phase transition in prostate cancer cells

Laboratory and epidemiological studies have indicated that 1alpha,25-dihydroxyvitamin D(3) [1alpha,25(OH)(2)D(3)] and dietary omega3-polyunsaturated fatty acids (PUFAs) are capable of inhibiting prostate cancer at the initiation and progression stages. The objective of this study is to investigate the influence of 1alpha,25(OH)(2)D(3) and PUFAs in the form of fish oil applied alone or in combination on cell cycle kinetics in the exponentially growing androgen-dependent and -independent prostate cancer cells. Our data indicate that the high passage androgen-independent cell line, LNCaP-c115 had a much greater inhibitory response at the level of the G(1)/S-phase transition in response to fish oil treatment than androgen-dependent low passage LNCaP-c38 cells. When LNCaP-c38 and LNCaP-c115 cells were treated with fish oil (50mug/ml), 1alpha,25(OH)(2)D(3) (10(-8)M) or fish oil (50mug/ml)+1alpha,25(OH)(2)D(3) (10(-8)M), a synergistic growth inhibitory effect was observed with 1alpha,25(OH)(2)D(3)+fish oil group in LNCaP-c115 cell line at the levels of the G(1)/S-phase transition and cell division. This interaction appears to be specific for androgen-independent prostate cancer cell lines. Based on these results, we hypothesize that dietary components, such as omega3PUFAs and Vitamin D, have the potential to delay the progression of prostate cancer cells to an aggressive and un-treatable state.

Effects of recombinant human growth hormone on growth of human gastric carcinoma xenograft model in nude mice

AIM: To study effects of recombinant human growth hormone (rhGH) on growth of a human gastric carcinoma cell in vivo.

METHODS: Experimental mice were divided into control group, rhGH group, oxaliplatin (L-OHP) group and rhGH+L-OHP group. Cultured human gastric carcinoma cells BGC823 were inoculated into right axilla of nude mice and carcinoma xenograft model was established successfully. Inhibitory rate of xenograft tumor growth was estimated by measuring tumor volume; expression of proliferating cell nuclear antigen (PCNA), Bax and Bcl-2 proteins of xenograft tumor was detected using immunohistochemical S-P method.

RESULTS: Tumor growth inhibitory rate, the positive expression rate of PCNA, Bax and Bcl-2 were 49.3%, 58.2%, 65.2% and 59.2% in rhGH+L-OHP group respectively; 46.6%, 62.5%, 59.7% and 64.7% in L-OHP group; 5.0%, 82.7%, 23.2% and 82.2% in rhGH group and 0, 77.8%, 23.5% and 80.3% in control group. There was significant difference between rhGH+L-OHP group (or L-OHP group ) and control group or rhGH group (P < 0.05), whereas there were no significant differences (P > 0.05) between L-OHP group and rhGH+L-OHP group and between rhGH group and control group.

CONCLUSION: rhGH does not accelerate the proli-feration of human gastric cancer cell in vivo.

Increased Insulin-Like Growth Factor I Receptor Expression and Signaling Are Components of Androgen-Independent Progression in a Lineage-Derived Prostate Cancer Progression Model

Apoptosis and inhibition of mitosis are primary mechanisms mediating androgen ablation therapy-induced regression of prostate cancer (PCa). However, PCa readily becomes androgen independent, leading to fatal disease. Up-regulated growth and survival signaling is implicated in development of resistance to androgen ablation therapy. We are testing the hypothesis that insulin-like growth factor (IGF) responsiveness is required for androgen-independent (AI) progression. Using the LNCaP human PCa progression model, we have determined that IGF-I-mediated protection from apoptotic stress and enhanced mitotic activity is androgen dependent in LNCaP cells but is androgen independent in lineage-derived C4-2 cells. Both cell lines exhibit androgen-responsive patterns of IGF-I receptor (IGF-IR) expression, activation, and signaling to insulin receptor substrate-2 and AKT. However, C4-2 cells express higher levels of IGF-IR mRNA and protein and exhibit enhanced IGF-I-mediated phosphorylation and downstream signaling under androgen-deprived conditions. In comparisons of naive and AI metastatic human PCa specimens, we have confirmed that IGF-IR levels are elevated in advanced disease. Together with our LNCaP/C4-2 AI progression model data, these results indicate that increased IGF-IR expression is associated with AI antiapoptotic and promitotic IGF signaling in PCa disease progression.

Growth hormone secretagogues: prospects and potential pitfalls

The growth hormone secretagogues (GHSs) are the first well-characterised agents that rejuvenate the growth hormone (GH)/insulin-like growth factor (IGF-1) axis. This property was discovered during investigations of the underlying causative mechanisms of age-related endocrine changes. Chronic administration of the long acting GHS, MK-0677, reverses the age-related decline in pulse-amplitude of GH secretion and restores IGF-1 levels producing profiles typical of young adults. This restoration is accompanied by improvements in body composition in frail elderly subjects. When given acutely, the GHSs also increase appetite. Following cloning and characterisation of the GHS-receptor (GHS-R) an endogenous ligand, ghrelin, was isolated and identified. Ghrelin shares the GH releasing and orexigenic properties of the GHSs. Studies using Ghsr-null mice confirmed that the GHS-R was the ghrelin-receptor; hence, the GHSs should be considered to be 'ghrelin mimetics.' Ghrelin levels are reported to decline during ageing, therefore long-acting GHSs are ideal candidates for ghrelin replacement therapy.

The potential autocrine/paracrine roles of ghrelin and its receptor in hormone-dependent cancer

Ghrelin is a recently identified 28 amino acid peptide capable of stimulating pituitary growth hormone release in humans. The actions of ghrelin are mediated via the naturally occurring ghrelin receptor, also known as the growth hormone secretagogue receptor (GHS-R). Ghrelin and its receptors are now being recognized as components of the growth hormone axis and are therefore potentially involved in tissue growth and development. As is the case for other members of this axis, evidence is rapidly emerging to indicate that ghrelin/GHS-R may play an important autocrine/paracrine role in some cancers. This review highlights the evidence for the expression, regulation and potential functional role of ghrelin and its receptor in hormone-dependent cancers, such as prostate and breast cancer.

Is insulin-like growth factor-1 monitoring useful in assessing the response to growth hormone of growth hormone-deficient children?

OBJECTIVE

To assess the relationship between insulin-like growth factor-1 (IGF-1), the growth hormone (GH) dose utilized to treat GH-deficient children and the changes noticed in height-standard deviation score (H-SDS) and height velocity (HV).

STUDY DESIGN

We studied 24 prepubertal GH-deficient patients with a mean age of 10.5 +/- 1.8 years and a mean bone age (BA) of 8.4 +/- 2.1 years. H-SDS for chronologic age (CA) and BA before therapy were -2.6 +/- 0.8 and -1.2 +/- 0.8, whereas height velocity (HV)-SDS was -1.1 +/- 1.5. Serum IGF-1 and insulin-like growth factor binding protein-3 (IGFBP-3) levels were measured before, after 6 and 12 months of GH, and correlated with the GH dose used. Based on the increment of IGF-1 used during treatment, patients were divided into 2 groups: G1 (>1 SDS) and G2 (<1 SDS). HV-SDS and interval height increases were analyzed.

RESULTS

HV-SDS, as well as H-SDS for CA and BA during the first year of treatment, were significantly greater than before therapy. IGF-1 SDS increased significantly during the first 6 months of therapy (P <.0003), but increased no further at 12 months despite the use of a higher GH dose (0.1 vs 0.14 IU/kg/day), whereas IGFBP-3 SDS increased at both 6 and 12 months. There was no correlation between the GH dose used and IGF-1 and IGFBP-3 levels. When patients were divided according to their IGF-1 increment during therapy, a significant increase in H-SDS for BA and in HV-SDS was noted only in group 2.

CONCLUSIONS

The increment in IGF-1 SDS during therapy did not correlate with the interval height increase. IGF-1 measurement may be helpful in monitoring compliance and safety, but seems to be less useful in adjusting the GH dose needed to treat prepubertal GH-deficient children.

IGFs and IGFBPs: role in health and disease

The insulin-like growth factors (IGFs), IGF-binding proteins (IGFBPs), and IGFBP proteases are the main regulators of somatic growth and cellular proliferation. IGFs are involved in growth pre-natally and post-natally. Dysregulation of the IGF axis can lead to growth disorders such as growth hormone deficiency and acromegaly. Pre-natally, this dysregulation can lead to IUGR or macrosomia. IGFs also have an important mitogenic action and play a role in tumorigenesis and cancer. These actions are regulated by co-interactions with IGFBPs, especially IGFBP-3. In addition to somatic growth and mitogenic activity, IGFs have hypoglycaemic and insulin sensitizing actions, and their dysregulation is involved in diabetes and its complications. In this chapter, we examine the role of IGFs and IGFBPs in growth, tumorigenesis and diabetes, and discuss treatment modalities for each disease involving the GH-IGF-IGFBP axis, including discussion of current in vitro and in vivo investigations in this field.

Mind-body effect: insulinlike growth factor-1; clinical depression; and breast, prostate, and other cancer risk-an unmeasured and masked mediator of potential significance?

A possible relation may exist between higher insulinlike growth factor (IGF)-1 levels and the risk of premenopausal breast, prostate, or other cancers from recent prospective and case-control studies. Separately, a large prospective study has shown a potential association between chronic depression and cancer risk, whereas other preliminary studies have suggested a link between increasing IGF levels with major depression. Other studies have found that certain standard cancer treatments reduce the effect and levels of IGF, and 1 small study has found that standard antidepressants may reduce IGF levels in some patients diagnosed with major depression. It is possible that IGF-1 (or other IGFs) may be a mediator between depression and cancer, because separately both have been implicated in the risk of various cancers. This hypothesis first and foremost relies on the unsettled notion that an actual relation already exists or may be found in the future. It requires more extensive investigation because several studies have not found an association between IGF or depression and cancer risk, and other limitations such as small sample sizes and other influential factors on IGF levels need to be elucidated. Whether or not a mind-body effect exists with cancer, as seems to be the case with other diseases, remains to be seen. Is depression a potential confounder of human studies that attempts to establish a relation between IGF and disease? All of the studies to date have attempted to at least determine the effect of a variety of factors on IGF levels-including age, sex, diet, family history, weight, smoking status-and then have adjusted their results accordingly. Depression has not been included in this list of potential factors that may need to be considered when analyzing IGF-1 data and cancer risks. The time seems ripe to at least define further the relation, if any, between IGF-1 and depression.

Acromegaly and the risk of cancer

Recent studies suggest that acromegaly might predispose to an increased risk of benign and malignant neoplasms, thus influencing the final outcome of the disease. The exact mechanism of neoplastic events in acromegaly has not been completely clarified. Several studies indicate an autocrine-paracrine role for growth hormone (GH) and insulin-like growth factor-I (IGF-I) in the proliferation of normal and neoplastic cells. The paper reviews the results of molecular, clinical and epidemiological data supporting a role for GH-IGF-I action in colon, prostate, breast and lung carcinogenesis inpatients with acromegaly.

Does the GH-IGF axis play a role in cancer pathogenesis?

Recent case-controlled studies have found increases in the serum levels of insulin-like growth factor-I (IGF-I) in subjects who had, or who eventually developed, prostate or premenopausal breast cancers. Since growth hormone (GH) increases IGF-I levels, concern has been raised regarding its potential role as a cancer initiation factor. The epidemiological studies, which indicate an association between serum IGF-I levels and cancer risk, have not established causality. In fact, several alternative explanations for the elevated serum IGF-I levels in cancer patients may be proposed based on human and animal models. First, an effect of IGF-I causing symptomatic benign tissue hyperplasia may result in an ascertainment bias leading to an initiation of procedures resulting in the diagnosis of asymptomatic cancers. Second, elevated serum IGF-I in cancer patients may originate within the tumor (as suggested by some animal studies). Thirdly, serum IGF-I may actually be a surrogate marker of tissue IGF-I levels or of nutritional factors, which are not under GH control and may be involved in cancer initiation. The role of GH in cancer initiation is further negated by the fact that in acromegaly, the incidence of cancer, other than possibly colonic neoplasia does not appear to be significantly increased. Furthermore, GH transgenic mice, with high IGF-I levels, do not develop breast, prostate, or colonic malignancies. It is known that IGFBP-3 can inhibit IGF action on cancer cells in vitro and also can induce apoptosis via an IGF-independent mechanism. Importantly, in addition to increasing IGF-I levels, GH also increases the serum levels of IGFBP-3 and serum IGFBP-3 levels have been shown to be negatively correlated with the risk of cancer in the above mentioned epidemiological studies and in a similar study on colon cancer. These studies suggest that cancer risk is increased in individuals in whom both high IGF-I levels and low IGFBP-3 levels are present. In subjects treated with GH, IGF-I and IGFBP-3 levels both rise together and are not within the elevated cancer-risk range, based on published studies. Long-term studies are needed to assess the potential risks, including the long-term cancer risk associated with GH therapy. These should take into account several factors, including the duration of exposure, the risk magnitude associated with the degree of serum IGF-I elevation, and the adjusted risk based on a concomitant increase in IGFBP-3 levels. Since GH treated patients often have sub-normal IGF-I serum levels, which normalize on therapy, one might predict that their cancer risk on GH therapy should not increase above the normal population. Until further research in the area dictates otherwise, on-going cancer surveillance and routine monitoring of serum IGF-I and IGFBP-3 levels in GH-recipients should be the standard of care. At present, the data that are available do not warrant a change in our current management of approved indications for GH therapy.