• 제목/요약/키워드: insulin-like growth factor binding protein

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제대혈에서 아디포넥틴, 렙틴, 인슐린, IGF-I, IGFBP-3와 신생아의 신체계측과의 상관관계 (The relationship between adiponectin, leptin, insulin, insulin-like growth factor and IGF binding protein-3 in cord blood and neonatal anthropometric parameters)

  • 조혜정;김지영;김미진;황일태;이혜란
    • Clinical and Experimental Pediatrics
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    • 제51권7호
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    • pp.722-728
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    • 2008
  • 목 적 : 건강한 만삭아의 제대혈에서 아디포넥틴, 렙틴, 인슐린, IGF-I, IGFBP-3를 측정하여 출생체중, 신장, 지방량과의 관계를 알아보고자 하였다. 또한 적정 체중아 그룹에서 이 호르몬들의 출생후 1개월 동안 변화에 대해서 살펴보기로 하였다. 방 법 : 임신과 관련된 합병증이 없었던 산모에서 태어난 200명의 건강한 만삭아(남아 109명, 여아 91명)를 대상으로 하여 제대혈을 채취하여 혈장과 혈청을 분리하였고 출생체중, 출생신장, 머리둘레, 가슴둘레, 피부두께를 측정하였으며 폰더랄지수를 계산하였다. 대상 신생아들을 출생체중에 따라 AGA (n=132), SGA (n=29), LGA (n=39)의 세 그룹으로 나누었다. 적정체중아 중 15명에서 생후 3일, 7일, 30일에 신생아의 혈액을 채취하여 제대혈과 같은 방법으로 분리하였고 체중과 신장을 측정하였다. 결 과 : 아디포넥틴과 인슐린, IGF-I은 AGA, LGA군보다 SGA군에서 더 낮았다. 렙틴은 AGA, SGA군보다 LGA군에서 더 높았다. 아디포넥틴과 렙틴, 인슐린, IGF-I, IGFBP-3는 출생체중과 피부두께의 합과 양의 상관관계에 있었다. 출생 시 신장과 양의 상관관계를 보인 호르몬은 아디포넥틴, 렙틴, IGF-I이었다. 아디포넥틴은 렙틴과 양의 상관관계를 보였으나 인슐린, IGF-I, IGFBP-3와는 상관관계가 없었다. IGF-I은 남아보다 여아에서 더 높은 수치를 보였다. 출생 후 1개월 동안 렙틴은 생후 7일까지는 생리적 체중감소와 더불어 감소하다가 그 후 증가하였고 IGF-I 또한 생후 3일에 감소하다가 1개월 후 급격한 증가를 보였다. 결 론 : 아디포넥틴과 렙틴, 인슐린, IGF-I, IGFBP-3 모두 태아의 성장에 중요한 역할을 하며, 아디포넥틴은 인슐린, IGF-I 축과는 다른 기전으로 태아의 성장을 조절한다고 생각할 수 있었다. IGF-I은 남아에서보다 여아에서 더 높은 수치를 보여서 IGF-I의 성별간의 차이가 자궁 내에서도 존재하였다. 생후 1개월 동안의 성장에 다른 호르몬보다 IGF-I 이 더 중요한 역할을 한다는 사실을 알 수 있었다.

Induction of Apoptosis by IGFBP3 Overexpression in Hepatocellular Carcinoma Cells

  • Han, Jian-Jun;Xue, De-Wen;Han, Qiu-Rong;Liang, Xiao-Hong;Xie, Li;Li, Sheng;Wu, Hui-Yong;Song, Bao
    • Asian Pacific Journal of Cancer Prevention
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    • 제15권23호
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    • pp.10085-10089
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    • 2015
  • Background: The insulin-like growth factor (IGF) system comprises a group of proteins that play key roles in regulating cell growth, differentiation, and apoptosis in a variety of cellular systems. The aim of this study was to investigate the role of insulin-like growth factor binding protein 3 (IGFBP3) in hepatocellular carcinoma. Materials and Methods: Expression of IGF2, IGFBP3, and PTEN was analyzed by qRT-PCR. Lentivirus vectors were used to overexpress IGFBP3 in hepatocellular carcinoma cell (HCC) lines. The effect of IGFBP3 on proliferation was investigated by MTT and colony formation assays. Results: Expression of IGF2, IGFBP3, and PTEN in several HCC cell lines was lower than in normal cell lines. After 5-aza-2'-deoxycytidine/trichostatin A treatment, significant demethylation of the promoter region of IGFBP3 was observed in HCC cells. Overexpression of IGFBP3 induced apoptosis and reduced colony formation in HUH7 cells. Conclusions: Expression of IGF2, IGFBP3, and PTEN in several HCC cell lines was lower than in normal cell lines. After 5-aza-2'-deoxycytidine/trichostatin A treatment, significant demethylation of the promoter region of IGFBP3 was observed in HCC cells. Overexpression of IGFBP3 induced apoptosis and reduced colony formation in HUH7 cells.

Interaction between IGFBP-5 and TNFR1

  • Kim, Eun-Jung;Jeong, Mi-Suk;Hwang, Jae-Ryoung;Lee, Je-Ho;Jang, Se-Bok
    • Bulletin of the Korean Chemical Society
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    • 제31권7호
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    • pp.2019-2024
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    • 2010
  • Insulin-like growth factor binding protein 5 (IGFBP-5) plays an important role in controlling cell survival, differentiation and apoptosis. Apoptosis can be induced by an extrinsic pathway involving the ligand-mediated activation of death receptors such as tumor necrosis factor receptor 1 (TNFR1). To determine whether IGFBP-5 and TNFR1 interact as members of the same apoptosis pathway, recombinant IGFBP-5 and TNFR1 were isolated. The expression and purification of the full-length TNFR1 and truncated IGFBP-5 proteins were successfully performed in E. coli. The binding of both IGFBP-5 and TNFR1 proteins was detected by surface plasmon resonance spectroscopy (BIAcore), fluorescence measurement, electron microscopy, and size-exclusion column (SEC) chromatography. IGFBP-5 indeed binds to TNFR1 with an apparent $K_D$ of 9 nM. After measuring the fluorescence emission spectra of purified IGFBP-5 and TNFR1, it was found that the tight interaction of these proteins is accompanied by significant conformational changes of one or both. These results indicate that IGFBP-5 acts potently as a novel ligand for TNFR1.

Insulin-like Growth Factor Systems의 생식기능에서의 역할;자궁편 (Roles of the Insulin-like Growth Factor System in the Reproductive Function;Uterine Connection)

  • 이철영
    • Clinical and Experimental Reproductive Medicine
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    • 제23권3호
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    • pp.247-268
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    • 1996
  • 여포와 난포의 성숙, 배란과 착상, 임신의 유지와 태아의 성장 발달, 분만 및 유선발육과 비유 등 일련의 생식현상에서 있어서 성선자극호르몬과 스테로이드 호르몬의 작용이 중추적인 역할을 한다는 사실은 오래 전부터 알려져왔다. 그러나 이러한 일련의 현상에 고전적인 호르몬 외에도 다수의 성장인자가 관여되고 있음이 최근의 연구 결과 밝혀지고 있다. 생식기관에서 성장인자들은 대부분 autocrine/paracrine mode로 작용하여, 성선자극호르몬과 스테로이드 호르몬의 작용을 매개하거나 이들 호르몬 등과 교호적인 작용(synergy)을 한다. 생식기관 내 insulin-like growth factor(IGF) system은 최근 가장 활발히 연구된 분야 중의 하나로 생식현상의 전반에 걸쳐 중요한 역할을 하고 있음이 밝혀졌다. 본 지면에서는 IGF system에 관한 개괄적인 정보를 소개하고 현재까지 보고된 intrauterine IGF system에 관한 연구를 요약하고자 한다. IGF family는 IGF-I과 IGF-II ligands, 두종류의 IGF receptors(수용체), 그리고 지금까지 발견된 6종류의 IGF-binding proteins(IGFBPs)로 이루어져 있다. IGF-I과 IGF-II는 proinsulin과 상동한 구조를 가진 peptide로서 포도당과 아미노산 운반을 자극하는 등 insulin과 유사한 작용을 한다. 이 외에도 IGFs는 세포분열촉진제(mitogens)로서 여러 형태의 세포에 걸쳐 세포증식을 자극하고, 세포의 분화(differentiation)과 세포기능의 발현에 관여한다. IGFs는 간과 주로 messenchymal cells에서 발현되어 endocrine mode는 물론 autocrine/paracrine mode로 거의 모든 조직에 작용한다. IGF 수용체는 두종류가 알려져 있는데 type I IGF receptor는 tyrosine kinase로서 IGF-I과 IGF-II에 공히 high-affinity를 나타내고, 상기한 대부분의 IGFs의 작용을 매개한다. Type II IGF receptor 혹은 IGF-II/mannose-6-phosphate receptor는 두개의 서로 다른 binding sites를 가지고 있는데 IGF-II binding site는 IGF-II에만 high-affinity를 나타낸다. Type II IGF receptor의 주요 역할은 IGF-II를 lysosomal targeting하여 ligand를 파괴하는데 있다. 체액 속의 IGFs는 대부분 IGFBP에 결합되어 있다. IGFBPs는 IGF의 저장/운반체 혹은 IGF 작용을 조절하는 역할을 하는 것으로 알려져 있으나 개개 IGFBP의 역할에 대해서는 지극히 제한된 정보만이 알려져 있다. IGFBPs의 IGF ligands에의 affinity는 IGF receptors의 IGFs에의 affinity보다 크기 때문에 대부분의 in vitro 상황 하에서 IGFBPs는 IGF 작용을 억제한다. IGFBP에 결합되어 있는 IGF가 어떤 기작에 의해 IGFBP로부터 분리되어 IGF receptor에 도달하는지는 알려지지 않고 있으나, 혈액과 조직액에 들어있는 불특정 IGFBP protease activity는 IGF의 방출과정에서 일역을 하는 것으로 믿어지고 있다. 최근 연구보고에 의하면 특정 in vitro 상황 하에서 IGFBP-1, -3, -5 등은 IGF와 무관한 작용도 있다는 증빙이 있어 IGF system의 또 다른 차원을 예고하고 있다. IGF family members의 mRNAs & proteins는 영장류, 설치류 및 가축의 자궁조직과 수태물(conceptus)에서 발현되어 자궁과 태아의 성장 발달에 중요한 역할을 한다. 자궁조직의 IGF system의 발현은 성선호르몬, 국소 생리조절인자 등에 의해 발현시기와 장소의 특이성이 결정되며, 발현된 IGFs와 IGFBPs는 autocrine/paracrine mode로 자궁조직에 작용하기도 하고, 자궁강에 분비되어 수태물의 성장 발달에 관여한다. 착상을 전후하여 수태물에서도 IGF system이 발현되는데 개개 IGF family member의 발현 시기는 모체로부터 유래된 mRNA의 유무, 수태물 자체의 genetic programming, 모체와의 상호작용 등에 의해 결정되고, IGFs의 작용 부위 역시 시간(생리적 상태)과 장소의 특이성이 있다. 이와같이 conceptus IGF system의 발현이 시간적, 공간적으로 조절되고있다는 사실은 IGFs가 수태물의 성장 발달에 일역을 한다는 가설을 간접적으로 지지해 준다. 자궁조직과 수태물에서 발현된 IGFs는 세포의 증식과 분화, 포도당과 아미노산의 운반과 단백질합성, placental lactogen과 prolactin 등과 같은 유선자극호르몬의 생성을 자극하고 스테로이드 호르몬의 합성에도 관여한다. 태아의 성장 발달에 있어서 IGFs의 역할은 embryo의 IGF-I, IGF-II, 혹은 IGF receptor gene을 homologous recombination technique에 의해 파괴(gene targeting)하여을 때의 결과로써 입증되었다. 생쥐의 IGF and/or IGF-II gene 혹은 IGF receptor gene을 파괴했을 때 출생 전후 모두 성장 발달이 지연되며 출생시 무게는 정상치의 30-60% 수준에 머물고, 특히 type I IGF receptor gene 혹은 IGF-I과 IGF-II genes를 모두 파괴했을 경우에는 출생 후 곧 치사한다. 자궁 내의 IGFBPs는 IGF ligands를 자궁 내에 제한시키거나 IGFs의 receptor binding을 억제하는 negative regulators 역할을 하는 것으로 믿어지고 있다. 그러나 영장류의 자궁에서 IGFBP-I과 같은 특정 IGFBP는 IGFs보다 월등히 많은 양이 발현 분비되고 있는 것으로 추산되고 있으며, 또한 이 단백질은 모체탈락막세포에서 분비되는 주요 단백질 중의 하나라는 점을 감안할 때 IGFBP-I이 IGF과 무관한 작용이 있을 가능성도 배제할 수 없다. 따라서 IGFBPs의 역할 규명은 IGF system을 이해하는데 중요한 부분을 차지하고 있어 향후 이 분야의 연구에 많은 기대와 촛점이 모여지고 있다.

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Determination of optimal dietary valine concentrations for improved growth performance and innate immunity of juvenile Pacific white shrimp Penaeus vannamei

  • Daehyun Ko;Chorong Lee;Kyeong-Jun Lee
    • Fisheries and Aquatic Sciences
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    • 제27권3호
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    • pp.171-179
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    • 2024
  • A study was conducted to evaluate dietary valine (Val) requirement for Pacific white shrimp (Penaeus vannamei). Five isonitrogenous (353 g/kg) and isocaloric (4.08 kcal/g) semi-purified diets containing graded levels of Val (2.7, 5.1, 8.7, 12.1 or 16.0 g/kg) were formulated. Quadruplicate groups of 12 shrimp (average body weight: 0.46 ± 0.00 g) were fed one of the experimental diets (2%-5% of total body weight) for 8 weeks. Maximum weight gain was observed in 8.7 g/kg Val group. However, the growth performance was reduced when Val concentration in diets were higher than 12.1 g/kg. Feed conversion ratio was significantly increased with 2.7 and 16.0 g/kg Val inclusion. Shrimp fed the diets containing 2.7 g/kg Val showed significantly lower protein efficiency ratio, whole-body crude protein and Val concentrations. Dietary inclusion of Val significantly improved the relative expression of insulin-like growth factor binding protein and immune-related genes (prophenoloxidase, lysozyme and crustin) in the hepatopancreas and 8.7 g/kg Val group showed highest expression among all the groups. The dietary requirement of Val for maximum growth of juvenile P. vannamei, estimated using polynomial regression analysis on growth, was 9.54 g/kg of Val (27.2 g/kg based on protein level) and maximum growth occurred at 9.27 g/kg of Val (26.2 g/kg based on protein level) based on broken-line regression analysis.

Differential Gene Expression in Estradiol-3-Benzoate-Treated Liver and Chemically- Induced Hepatocellular Carcinoma

  • KIM , SEYL;KANG, JIN-SEOK;JANG, DONG-DEUK;LEE, KOOK-KYUNG;KIM, SOON-AE;HAN, BEOM-SEOK;PARK, YOUNG-IN
    • Journal of Microbiology and Biotechnology
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    • 제14권6호
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    • pp.1286-1294
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    • 2004
  • In a previous study by the current authors, hepatocellular carcinoma (HCC) was determined to be epidemiologically sex-dependent, and the incidence and multiplicity of HCC found to decrease in estradiol-3 benzoate (EB)-treated F344 rats. Therefore, to ascertain the anticancer mechanism of EB, a commercially available cDNA microarray, with a total of 14,815 cDNA rat gene clones, was used to determine the differentially expressed genes in nontreated livers, EB-treated livers, and diethynitrosolamine (DEN)-induced HCC. In the sequenced experiment, a total of 85 genes were differentially expressed at either two or more times the rate of the normal expression, where 33 genes were downregulated by EB, and 52 genes upregulated. Candidate genes were selected according to significant changes observed in the mRNA expression in the EB-treated livers compared with the nontreated livers, then these genes were filtered according to their different expression patterns in the DEN-induced tumors compared to the estrogen-treated livers. To confirm the microarray data, a real-time PCR analysis was performed for ten selected genes: the H-ras revertant protein 107 (H­rev107), insulin-like growth factor binding protein (lOFBP), parathyroid hormone receptor (PI'HR), SH3 domain binding protein (SH3BP), metallothionein, src-suppressed C-kinase substrate (SSeCK) gene, phosphodiesterase I, CD44, epithelial membrane protein 3 (EMP3), and estrogen receptor a (ERa). The SSeCK and phosphodiesterase I genes were both upregulated in the DEN-induced hepatocarcinomas, yet their possible carcinogenic functions remain unknown. Meanwhile, the other genes were downregulated, including the genes related to growth regulation (IOFBP, H-revI07, ER$\alpha$), adipogenesis inhibition (PTHR), and tumor suppression (metallothionein).

Prostate Cancer Risk in Relation to a Single Nucleotide Polymorphism in the Insulin-like Growth Factor-binding Protein-3 (IGFBP3) Gene: a Meta-analysis

  • Mao, Ye-Qing;Xu, Xin;Lin, Yi-Wei;Chen, Hong;Hu, Zheng-Hui;Xu, Xiang-Lai;Zhu, Yi;Wu, Jian;Zheng, Xiang-Yi;Qin, Jie;Xie, Li-Ping
    • Asian Pacific Journal of Cancer Prevention
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    • 제13권12호
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    • pp.6299-6303
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    • 2012
  • Insulin-like growth factor-binding protein-3 (IGFBP3) has been identified as a putative tumor suppressor with multifunctional roles in the IGF axis. Recently, there have been a growing body of studies investigating the relation between the IGFBP3 A-202C polymorphism, circulating IGFBP3 and prostate cancer risk, but their outcomes varied leading to controversy. Hence, it is necessary to perform a meta-analysis covering all eligible studies to shed a light on the association of IGFBP3 A-202C and cancer risk. Finally, we included a total of 11 relevant articles between 2003 and 2010 covering 14 case-control studies including 9,238 cases and 8,741 controls for our analysis. Our results showed that A-202C was a marginal risk factor of prostate cancer (allele contrast: OR=1.08, 95% CI :1.01-1.16; dominant model: OR=1.11, 95% CI :1.01-1.22; heterozygote codominant model: OR=1.11, 95% CI :1.03-1.18; homozygote contrast: OR=1.19, 95% CI :1.03-1.37). Stratification analysis revealed that sample size and control source were two major heterogeneous meta-factors especially in the recessive model (source: Population-based control group :p=0.30,I2=16.7%, Hospital-based control group: p=0.20, I2=30.3%; sample size: Small: p=0.22,I2= 32.8%, Medium: p=0.09,I2=48%, Large p=0.60,I2=0.0%); However, contrary to previous findings, no significance was found in racial subgroups. No significant publication bias was found in our analysis. Considering the robustness of the results and the discrepancy among some studies, there might be some unsolved confounding factors, and further more critical large studies are needed for confirmation.

Human umbilical cord blood mesenchymal stem cells engineered to overexpress growth factors accelerate outcomes in hair growth

  • Bak, Dong Ho;Choi, Mi Ji;Kim, Soon Re;Lee, Byung Chul;Kim, Jae Min;Jeon, Eun Su;Oh, Wonil;Lim, Ee Seok;Park, Byung Cheol;Kim, Moo Joong;Na, Jungtae;Kim, Beom Joon
    • The Korean Journal of Physiology and Pharmacology
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    • 제22권5호
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    • pp.555-566
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    • 2018
  • Human umbilical cord blood mesenchymal stem cells (hUCB-MSCs) are used in tissue repair and regeneration; however, the mechanisms involved are not well understood. We investigated the hair growth-promoting effects of hUCB-MSCs treatment to determine whether hUCB-MSCs enhance the promotion of hair growth. Furthermore, we attempted to identify the factors responsible for hair growth. The effects of hUCB-MSCs on hair growth were investigated in vivo, and hUCB-MSCs advanced anagen onset and hair follicle neogeneration. We found that hUCB-MSCs co-culture increased the viability and up-regulated hair induction-related proteins of human dermal papilla cells (hDPCs) in vitro. A growth factor antibody array revealed that secretory factors from hUCB-MSCs are related to hair growth. Insulin-like growth factor binding protein-1 (IGFBP-1) and vascular endothelial growth factor (VEGF) were increased in co-culture medium. Finally, we found that IGFBP-1, through the co-localization of an IGF-1 and IGFBP-1, had positive effects on cell viability; VEGF secretion; expression of alkaline phosphatase (ALP), CD133, and ${\beta}-catenin$; and formation of hDPCs 3D spheroids. Taken together, these data suggest that hUCB-MSCs promote hair growth via a paracrine mechanism.

Alterations of mRNA and lncRNA profiles associated with the extracellular matrix and spermatogenesis in goats

  • Chen, Haolin;Miao Xiaomeng;Xu, Jinge;Pu, Ling;Li, Liang;Han, Yong;Mao, Fengxian;Ma, Youji
    • Animal Bioscience
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    • 제35권4호
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    • pp.544-555
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    • 2022
  • Objective: Spermatozoa are produced within the seminiferous tubules after sexual maturity. The expression levels of mRNAs and lncRNAs in testicular tissues are different at each stage of testicular development and are closely related to formation of the extracellular matrix (ECM) and spermatogenesis. Therefore, we set out to study the expression of lncRNAs and mRNAs during the different developmental stages of the goat testis. Methods: We constructed 12 RNA libraries using testicular tissues from goats aged 3, 6, and 12 months, and studied the functions of mRNAs and lncRNAs using the gene ontogeny (GO) and Kyoto encyclopedia of genes and genomes (KEGG) databases. Relationships between differentially expressed genes (DEGs) were analyzed by lncRNA-mRNA co-expression network and protein-protein interaction network (PPI). Finally, the protein expression levels of matrix metalloproteinase 2 (MMP2), insulin-like growth factor 2 (IGF2), and insulin-like growth factor-binding protein 6 (IGFBP6) were detected by western blotting. Results: We found 23, 8, and 135 differentially expressed lncRNAs and 161, 12, and 665 differentially expressed mRNAs that were identified between 3 vs 6, 6 vs 12, and 3 vs 12 months, respectively. GO, KEGG, and PPI analyses showed that the differential genes were mainly related to the ECM. Moreover, MMP2 was a hub gene and co-expressed with the lncRNA TCONS-0002139 and TCONS-00093342. The results of quantitative reverse-transcription polymerase chain reaction verification were consistent with those of RNA-seq sequencing. The expression trends of MMP2, IGF2, and IGFBP6 protein were the same as that of mRNA, which all decreased with age. IGF2 and MMP2 were significantly different in the 3 vs 6-month-old group (p<0.05). Conclusion: These results improve our understanding of the molecular mechanisms involved in sexual maturation of the goat testis.

Insulin-like growth factor가 소장 점막 세포 증식에 미치는 영향

  • 윤정한
    • 한국영양학회:학술대회논문집
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    • 한국영양학회 1995년도 추계학술대회 초록
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    • pp.11-34
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    • 1995
  • Growth hormone (GH) plays a key role in regulating postnatal growth and can stimulate growth of animals by acting directly on specific receptors on the plasma membrane of tissues or indirectly through stimulating insulin-like growth factor (IGF)-I synthesis and secretion by the liver and other tissues. IGF-I and IGF-Ⅱ are polypeptides with structural similarity with proinsulin that stimulate cell proliferation by endocrine, paracrine and autocrine mechanisms. The initial event in the metabolic action of IGFs on target cells appears to be their binding to specific receptors on the plasma membrane. Current evidence indicates that the mitogenic actions of both IGFs are mediated primarily by binding to the type I IGF receptors, and that IGF action is also mediated by interactions with IGF-binding proteins (IGFBPs). Six distinct IGFBPs have been identified that are characterized by cell-specific interaction, transcriptional and post-translational regulation by many different effectors, and the ability to either potentiate or inhibit IGF actions. Nutritional deficiencies can have their devastating consequence during growth. Although IGF-I is the major mediator of GH's action on somatic growth, nutritional status of an organism is a critical regulator of IGF-I and IGFBPs. Various nutrient deficiencies result in decreased serum IGF-I levels and altered IGFBP levels, but the blood levels of GH are generally unchanged or elevated in malnutrition. Effects of protein, energy, vitamin C and D, and zinc on serum IGF and IGFBP levels and tissue mRNA levels were reviewed in the text. Multiple factors are involved in the regulation of intestinal epithelial cell growth and differentiation. Among these factors the nutritional status of individuals is the most important. The intestinal epithelium is an important site for mitogenic action of the IGFs in vivo, with exogenous IGF-I stimulating mucosal hyperplasia. Therefore, the IGF system appears to provide and important mechanism linking nutrition and the proliferation of intestinal epithelial cells. In order to study the detailed mechanisms by which intestinal mucosa is regulated, we have utilized IEC-6 cells, an intestinal epithelial cell line and Caco-2 cells, a human colon adenocarcinoma cell line. Like intestinal crypt cells analyzed in vivo or freshly isolated intestinal epithelial cells, IEC-6 cells and Caco-2 cells possess abundant quatities of both type Ⅰ and type Ⅱ IGF receptors. Exogenous IGFs stimulate, whereas addition of IGFBP-2 inhibits IEC-6 cell proliferation. To investigate whether endogenously secreted IGFBP-2 inhibit proliferation, IEC-6 cells were transfected with a full-length rat IGFBP-2 cDNA anti-sense expression construct. IEC-6 cells transfected with anti-sense IGFBP-2 protein in medium. These cells grew at a rate faster than the control cells indicating that endogenous IGFBP-2 inhibits proliferation of IEC-6 cells, probably by sequestering IGFs. IEC-6 cells express many characteristics of enterocyte, but do not undergo differentiation. On the other hand, Caco-2 cells undergo a spontaneous enterocyte differentiation. On the other hand, Caco-2 cells undergo a spontaneous enterocyte differentiation after reaching confluency. We have demonstrated that Caco-2 cells produce IGF-Ⅱ, IGFBP-2, IGFBP-3, and an as yet unidentified 31,000 Mr IGFBP, and that both mRNA and peptide secretion of IGFBP-2 and IGFBP-3 increased, but IGFBP-4 mRNA and protein secretion decreased after the cells reached confluency. These changes occurred in parallel to and were coincident with differentiation of the cells, as measured by expression of sucrase-isomaltase. In addition, Caco-2 cell clones forced to overexpress IGFBP-4 by transfection with a rat IGFBP-4 cDNA construct exhibited a significantly slower growth rate under serum-free conditions and had increased expression of sucrase-isomaltase compared with vector control cells. These results indicate that IGFBP-4 inhibits proliferation and stimulates differentiation of Caco-2 cells, probably by inhibiting the mitogenic actions of IGFs.

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