Insulin-like growth factor 1 (IGF-1), also calledsomatomedin C, is ahormone similar inmolecular structure toinsulin which plays an important role in childhood growth, and hasanabolic effects in adults.[5] In the 1950s IGF-1 was called "sulfation factor" because it stimulated sulfation of cartilage in vitro,[6] and in the 1970s due to its effects it was termed "nonsuppressible insulin-like activity" (NSILA).[7]
IGF-1 is produced primarily by theliver. Production is stimulated bygrowth hormone (GH). Most of IGF-1 is bound to one of 6 binding proteins (IGF-BP). IGFBP-1 is regulated by insulin. IGF-1 is produced throughout life; the highest rates of IGF-1 production occur during thepubertal growth spurt.[12] The lowest levels occur in infancy and old age.[13][14]
Low IGF-1 levels are associated withcardiovascular disease, while high IGF-1 levels are associated withcancer. Mid-range IGF-1 levels are associated with the lowestmortality.
A synthetic analog of IGF-1,mecasermin, is used for the treatment ofgrowth failure in children with severe IGF-1 deficiency.[15]Cyclic glycine-proline (cGP) is a metabolite of hormone insulin-like growth factor-1 (IGF-1). It has a cyclic structure, lipophilic nature, and is enzymatically stable which makes it a more favourable candidate for manipulating the binding-release process between IGF-1 and its binding protein, thereby normalising IGF-1 function.[16]
Thepolypeptide hormone IGF-1 is synthesized primarily in theliver upon stimulation bygrowth hormone (GH). It is a key mediator of anabolic activities in numerous tissues and cells, such as growth hormone-stimulated growth,metabolism and protein translation.[17] Due to its participation in the GH-IGF-1 axis it contributes among other things to the maintenance of muscle strength, muscle mass, development of the skeleton and is a key factor in brain, eye and lung development during fetal development.[18]
Studies have shown the importance of the GH/IGF-1 axis in directing development and growth, where mice with an IGF-1 deficiency had a reduced body- and tissue mass. Mice with an excessive expression of IGF-1 had an increased mass.[19]
The levels of IGF-1 in the body vary throughout life, depending on age, where peaks of the hormone is generally observed during puberty and thepostnatal period. After puberty, when entering the third decade of life, there is a rapid decrease in IGF-1 levels due to the actions of GH. Between the third and eighth decade of life, the IGF-1 levels decrease gradually, but unrelated to functional decline.[18] However, protein intake is proven to increase IGF-1 levels.[20]
As a majorgrowth factor, IGF-1 is responsible for stimulating growth of all cell types, and causing significantmetabolic effects.[26] One important metabolic effect of IGF-1 is signaling cells that sufficientnutrients are available for them to undergohypertrophy andcell division.[27] Its effects also includeinhibitingcell apoptosis and increasing the production ofcellular proteins.[27] IGF-1 receptors are ubiquitous, which allows for metabolic changes caused by IGF-1 to occur in all cell types.[26] IGF-1's metabolic effects are far-reaching and can coordinateprotein,carbohydrate, andfat metabolism in a variety of different cell types.[26] The regulation of IGF-1's metabolic effects on target tissues is also coordinated with other hormones such as growth hormone and insulin.[28]
Similarly to IGF-1,IGF-2 is mainly produced in theliver and after it is released intocirculation, it stimulates growth and cell proliferation. IGF-2 is thought to be afetal growth factor, as it is essential for a normalembryonic development and is highlyexpressed in embryonic andneonataltissues.[31]
LS is a very rare condition with a total of 250 known individuals worldwide.[39][37] The genetic origins of these individuals have been traced back to Mediterranean, South Asian, and Semitic ancestors, with the latter group comprising the majority of cases.[37] Moleculargenetic testing for growth hormone receptor gene mutations confirms the diagnosis of LS, but clinical evaluation may include laboratory analysis of basal GH, IGF-1 and IGFBP levels, GH stimulation testing, and/or GH trial therapy.
Evidence has suggested that people with Laron syndrome have a reduced risk of developing cancer anddiabetes mellitus type II, with a significantly reducedincidence and delayed age of onset of these diseases compared to their unaffected relatives.[41][42] The molecular mechanisms of increased longevity and protection from age-related disease among people with LS is an area of active investigation.[43]
It has been suggested that consumption of IGF-1 indairy products could increase cancer risk, particularlyprostate cancer.[62][63] However, significant levels of intact IGF-1 from oral consumption are not absorbed as they are digested by gastric enzymes.[63][64] IGF-1 present in food is not expected to be active within the body in the way that IGF-1 is produced by the body itself.[63]
TheFood and Drug Administration has stated that IGF-I concentrations in milk are not significant when evaluated against concentrations of IGF-I endogenously produced in humans.[65]
A 2018 review by the Committee on Carcinogenicity of Chemicals in Food, Consumer Products and the Environment (COC) concluded that there is "insufficient evidence to draw any firm conclusions as to whether exposure to dietary IGF-1 is associated with an increased incidence of cancer in consumers".[63] Certain dairy processes such asfermentation are known to significantly decrease IGF-1 concentrations.[66] TheBritish Dietetic Association has described the idea that milk promotes hormone related cancerous tumor growth as a myth, stating "no link between dairy containing diets and risk of cancer or promoting cancer growth as a result of hormones".[67]
^Salmon WD, Daughaday WH (June 1957). "A hormonally controlled serum factor which stimulates sulfate incorporation by cartilage in vitro".The Journal of Laboratory and Clinical Medicine.49 (6):825–836.PMID13429201.
^Meuli C, Zapf J, Froesch ER (April 1978). "NSILA-carrier protein abolishes the action of nonsuppressible insulin-like activity (NSILA-S) on perfused rat heart".Diabetologia.14 (4):255–259.doi:10.1007/BF01219425.PMID640301.
^Höppener JW, de Pagter-Holthuizen P, Geurts van Kessel AH, Jansen M, Kittur SD, Antonarakis SE, et al. (1985). "The human gene encoding insulin-like growth factor I is located on chromosome 12".Human Genetics.69 (2):157–160.doi:10.1007/BF00293288.PMID2982726.S2CID5825276.
^Landin-Wilhelmsen K, Wilhelmsen L, Lappas G, Rosén T, Lindstedt G, Lundberg PA, et al. (September 1994). "Serum insulin-like growth factor I in a random population sample of men and women: relation to age, sex, smoking habits, coffee consumption and physical activity, blood pressure and concentrations of plasma lipids, fibrinogen, parathyroid hormone and osteocalcin".Clinical Endocrinology.41 (3):351–357.doi:10.1111/j.1365-2265.1994.tb02556.x.PMID7955442.S2CID24346368.
^Xie W, Tang Z, Guo Y, Zhang C, Zhang H, Han Y, et al. (September 2019). "Seasonal expressions of growth hormone receptor, insulin-like growth factor 1 and insulin-like growth factor 1 receptor in the scented glands of the muskrats (Ondatra zibethicus)".General and Comparative Endocrinology.281:58–66.doi:10.1016/j.ygcen.2019.05.014.PMID31121166.S2CID163168020.
^Moloney AM, Griffin RJ, Timmons S, O'Connor R, Ravid R, O'Neill C (February 2010). "Defects in IGF-1 receptor, insulin receptor and IRS-1/2 in Alzheimer's disease indicate possible resistance to IGF-1 and insulin signalling".Neurobiology of Aging.31 (2):224–243.doi:10.1016/j.neurobiolaging.2008.04.002.PMID18479783.S2CID14265087.
^Winston BW, Ni A, Aurora RC (2006). "Insulin-like Growth Factors". In Laurent GJ, Shapiro SD (eds.).Encyclopedia of Respiratory Medicine. pp. 339–346.doi:10.1016/B0-12-370879-6/00453-1.ISBN978-0-12-370879-3.GF-II appears to be essential for normal embryonic development and, as such, IGF-II is thought to be a fetal growth factor. IGF-II is highly expressed in embryonic and neonatal tissues and promotes proliferation of many cell types primarily of fetal origin.
^Carpenter V, Matthews K, Devlin G, Stuart S, Jensen J, Conaglen J, et al. (February 2008). "Mechano-growth factor reduces loss of cardiac function in acute myocardial infarction".Heart, Lung & Circulation.17 (1):33–39.doi:10.1016/j.hlc.2007.04.013.PMID17581790.
^Hamosh A, O'Neill M, Phillips J, McKusick V."# 262500 LARON SYNDROME".omim.org. McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine. Retrieved10 November 2020.
^Laron Z, Kauli R, Lapkina L, Werner H (2017). "IGF-I deficiency, longevity and cancer protection of patients with Laron syndrome".Reviews in Mutation Research.772 (123–133):123–133.doi:10.1016/j.mrrev.2016.08.002.PMID28528685.
^Werner H, Lapkina-Gendler L, Laron Z (2017). "Fifty years on: New lessons from the laron syndrome".Israel Medical Association Journal.19 (1):6–7.PMID28457105.
^"Acromegaly - NIDDK".National Institute of Diabetes and Digestive and Kidney Diseases. Retrieved11 May 2024.
^Shen Y, Zhang J, Zhao Y, Yan Y, Liu Y, Cai J (April 2015). "Diagnostic value of serum IGF-1 and IGFBP-3 in growth hormone deficiency: a systematic review with meta-analysis".European Journal of Pediatrics.174 (4):419–427.doi:10.1007/s00431-014-2406-3.PMID25213432.
^Haj-Ahmad LM, Mahmoud MM, Sweis NW, Bsisu I, Alghrabli AM, Ibrahim AM, et al. (March 2023). "Serum IGF-1 to IGFBP-3 Molar Ratio: A Promising Diagnostic Tool for Growth Hormone Deficiency in Children".The Journal of Clinical Endocrinology and Metabolism.108 (4):986–994.doi:10.1210/clinem/dgac609.PMID36251796.
^Lambrecht N (March 2023). "IGF-1/IGFBP-3 Serum Ratio as a Robust Measure to Determine GH Deficiency and Guide Human Recombinant GH Therapy".The Journal of Clinical Endocrinology and Metabolism.108 (4):e54 –e55.doi:10.1210/clinem/dgac687.PMID36454697.
^Phillips JD, Yeldandi A, Blum M, de Hoyos A (October 2009). "Bronchial carcinoid secreting insulin-like growth factor-1 with acromegalic features". primary.The Annals of Thoracic Surgery.88 (4):1350–1352.doi:10.1016/j.athoracsur.2009.02.042.PMID19766843.
^abKazemi A, Speakman JR, Soltani S, Djafarian K (June 2020). "Effect of calorie restriction or protein intake on circulating levels of insulin like growth factor I in humans: A systematic review and meta-analysis".Clinical Nutrition.39 (6):1705–1716.doi:10.1016/j.clnu.2019.07.030.PMID31431306.
^Li T, Zhao Y, Yang X, Feng Y, Li Y, Wu Y, et al. (December 2022). "Association between insulin-like growth factor-1 and cardiovascular events: a systematic review and dose-response meta-analysis of cohort studies".Journal of Endocrinological Investigation.45 (12):2221–2231.doi:10.1007/s40618-022-01819-1.PMID35596917.S2CID248924624.
^Yuen KC, Dunger DB (January 2007). "Therapeutic aspects of growth hormone and insulin-like growth factor-I treatment on visceral fat and insulin sensitivity in adults".Diabetes, Obesity & Metabolism.9 (1):11–22.doi:10.1111/j.1463-1326.2006.00591.x.PMID17199714.
![3lri: Solution structure and backbone dynamics of long-[Arg(3)]insulin-like growth factor-I](/mt/?noimg=&dark=on&url=https%3a%2f%2fen.wikipedia.org%2fwiki%2fFile%3aPDB_3lri_EBI.jpg)