Insulin-like growth factor-I receptor in proliferation and motility of pancreatic cancer

AIM:To develop a molecular therapy for pancreatic cancer, the insulin-like growth factor-I (IGF-I) signaling pathway was analyzed.METHODS: Pancreatic cancer cell lines (MIA-Paca2, NOR-P1, PANC-1, PK-45H, PK-1, PK-59 and KP-4) were cultured in media with 10 mL/L fetal bovine serum. Western blotting analysis was performed to clarify the expression of IGF-I receptor (IGF-IR). Picropodophyllin (PPP), a specific inhibitor of IGF-IR, LY294002, a specific inhibitor of phosphatidylinositol3 kinase (PI3K), and PD98059, a specific inhibitor of mitogen-activated protein kinase, were added to the media. After 72 h, a 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt (MTS) assay was performed to analyze cell proliferation. A wound assay was performed to analyze cell motility with hematoxylin and eosin (HE) staining 48 h after addition of each inhibitor. RESULTS: All cell lines clearly expressed not only IGF-IR but also phosphorylated IGF-IR. PPP significantly suppressed proliferation of MIA-Paca2, NOR-P1, PANC-1, PK-45H, PK-1, PK-59 and KP-4 cells to 36.9% ± 2.4% (mean ± SD), 30.9% ± 5.5%, 23.8% ± 3.9%, 37.1% ± 5.3%, 10.4% ± 4.5%, 52.5% ± 4.5% and 22.6% ± 0.4%, at 2 μmol/L, respectively (P < 0.05). LY294002 significantly suppressed proliferation of MIA-Paca2, NOR-P1, PANC-1, PK-45H, PK-1, PK-59 and KP-4 cells to 44.4% ± 7.6%, 32.9% ± 8.2%, 53.9% ± 8.0%, 52.8% ± 4.0%, 32.3% ± 4.2%, 51.8% ± 4.5%, and 30.6% ± 9.4%, at 50 μmol/L, respectively (P < 0.05). PD98059 did not significantly suppress cell proliferation. PPP at 2 μmol/L suppressed motility of MIA-Paca2, NOR-P1, PANC-1, PK-45H, PK-1, PK-59 and KP-4 cells to 3.0% ± 0.2%, 0%, 0%, 2.0% ± 0.1%, 5.0% ± 0.2%, 3.0% ± 0.1%, and 5.0% ± 0.2%, respectively (P < 0.05). LY294002 at 50 μmol/L suppressed motility of MIA-Paca2, NOR-P1, PANC-1, PK-45H, PK-1, PK-59 and KP-4 to 3.0% ± 0.2%, 0%, 3.0% ± 0.2%, 0%, 0%, 0% and 3% ± 0.1%, respectively (P < 0.05). PD980509 at 20 μmol/L did not suppress motility. Cells were observed by microscopy to analyze the morphological changes induced by the inhibitors. Cells in medium treated with 2 μmol/L PPP or 50 μmol/L LY294002 had pyknotic nuclei, whereas those in medium with 20 μmol/L PD98059 did not show apoptosis.CONCLUSION: IGF-IR and PI3K are good candidates for molecular therapy of pancreatic cancer.

A candidate targeting molecule of insulin-like growth factor-Ⅰ receptor for gastrointestinal cancers

Advances in molecular research in cancer have brought new therapeutic strategies into clinical usage.One new group of targets is tyrosine kinase receptors,which can be treated by several strategies,including small molecule tyrosine kinase inhibitors(TKIs) and monoclonal antibodies(mAbs).Aberrant activation of growth factors/receptors and their signal pathways are required for malignant transformation and progression in gastrointestinal(GI) carcinomas.The concept of targeting specif ic carcinogenic receptors has been validated by successful clinical application of many new drugs.Type I insulin-like growth factor(IGF) receptor(IGF-IR) signaling potently stimulates tumor progression and cellular differentiation,and is a promising new molecular target in human malignancies.In this review,we focus on this promising therapeutic target,IGF-IR.The IGF/IGF-IR axis is an important modifier of tumor cell proliferation,survival,growth,and treatment sensitivity in many malignant diseases,including human GI cancers.Preclinical studies demonstrated that downregulation of IGF-IR signals reversed the neoplastic phenotype and sensitized cells to anticancer treatments.These results were mainly obtained through our strategy of adenoviruses expressing dominant negative IGF-IR(IGF-IR/dn) against gastrointestinal cancers,including esophagus,stomach,colon,and pancreas.We also summarize a variety of strategies to interrupt the IGFs/IGF-IR axis and their preclinical experiences.Several mAbs and TKIs targeting IGF-IR have entered clinical trials,and early results have suggested that these agents have generally acceptable safety profiles as single agents.We summarize the advantages and disadvantages of each strategy and discuss the merits/demerits of dual targeting of IGF-IR and other growth factor receptors,including Her2 and the insulin receptor,as well as other alternatives and possible drug combinations.Thus,IGF-IR might be a candidate for a molecular therapeutic target in human GI carcinomas.

Overexpression of insulin-like growth factor-Ⅰ receptor as a pertinent biomarker for hepatocytes malignant transformation

AIM: To investigate the dynamic features of insulin-like growth factor-I receptor (IGF-IR) expression in rat hepatocarcinogenesis, and the relationship between IGF-IR and hepatocytes malignant transformation at mRNA or protein level.METHODS: Hepatoma models were made by inducing with 2-fluorenylacetamide (2-FAA) on male Sprague-Dawley rats. Morphological changes of hepatocytes were observed by pathological Hematoxylin and eosin staining, the dynamic expressions of liver and serum IGF-IR were quantitatively analyzed by an enzyme-linked immunosorbent assay. The distribution of hepatic IGF-IR was located by immunohistochemistry. The fragments of IGF-IR gene were amplified by reverse transcription-polymerase chain reaction, and confirmed by sequencing.RESULTS: Rat hepatocytes after induced by 2-FAA were changed dynamically from granule-like degeneration, precancerous to hepatoma formation with the progressing increasing of hepatic mRNA or IGF-IR expression. The incidences of liver IGF-IR, IGF-IR mRNA, specific IGF-IR concentration (ng/mg wet liver), and serum IGF-IR level (ng/mL) were 0.0%, 0.0%, 0.63 ± 0.17, and 1.33 ± 0.47 in the control; 50.0%, 61.1%, 0.65 ± 0.2, and 1.51 ± 0.46 in the degeneration; 88.9%, 100%, 0.66 ± 0.14, and 1.92 ± 0.29 in the precancerosis; and 100%, 100%, 0.96 ± 0.09, and 2.43 ± 0.57 in the cancerous group, respectively. IGF-IR expression in the cancerous group was significantly higher (P < 0.01) than that in any of other groups at mRNA or protein level. The closely positive IGF-IR relationship was found between livers and sera (r = 0.91, t = 14.222, P < 0.01), respectively.CONCLUSION: IGF-IR expression may participate in rat hepatocarcinogenesis and its abnormality should be an early marker for hepatocytes malignant transformation.

Intestinal hormones and growth factors:Effects on the small intestine

There are various hormones and growth factors which may modify the intestinal absorption of nutrients, and which might thereby be useful in a therapeutic setting, such as in persons with short bowel syndrome. In part I, we focus first on insulin-like growth factors, epidermal and transferring growth factors, thyroid hormones and glucocorticosteroids. Part Ⅱ will detail the effects of glucagon-like peptide （GLP）-2 on intestinal absorption and adaptation, and the potential for an additive effect of GLP2 plus steroids.

Effect of growth hormone on small intestinal homeostasis relation to cellular mediators IGF-I and IGFBP-3

AIM:To evaluate the effects of growth hormone(GH) on the histology of small intestines which might be related to the role of insulin like growth factor(IGF)-I, IGF-binding protein 3(IGFBP-3)and its receptors. METHODS:Twelve week-old adult male Wistar albino rats were divided into two groups.The study group(n =10),received recombinant human growth hormone (rGH)at a dose of 2 mg/kg per day subcutaneously for 14 d and the control group(n=10)received physiologic serum.Paraffin sections of jejunum were stained with periodic acid shift(PAS)and hematoxylin and eosin(HE) for light microscopy.They were also examined for IGF-I, IGFBP-3 and IGF-receptor immunoreactivities.Staining intensity was graded semi-quantitatively using the HS- CORE. RESULTS:Goblet cells and the cells in crypt epitheliawere significantly increased in the study group compared to that of the control group.We have demonstrated an increase of IGF-I and IGFBP-3 immunoreactivities in surface epithelium of the small intestine by GH application.IGF-I receptor immunoreactivities of crypt,villous columnar cells,enteroendocrine cells and muscularis mucosae were also more strongly positive in the study group compared to those of in the control group. CONCLUSION:These findings confirm the important trophic and protective role of GH in the homeostasis of the small intestine.The trophic effect is mediated by an increase in IGF-I synthesis in the small intestine, but the protective effect is not related to IGF-I.

Delirium,insulin-like growth factor I,growth hormone in older inpatients

BACKGROUND Delirium is a common disorder in elderly medical inpatients with serious adverse outcomes and is characterized by sudden onset,disturbance in attention,awareness,consciousness and cognition,and often with behavioural disturbances.Central to understanding delirium,is understanding mechanisms by which body and brain wellbeing are linked and in particular how brain responses to bodily homeostatic stress is mediated.A number of studies have investigated the relationship between insulin-like growth factor I(IGF-I)and delirium in medically ill hospitalised patients with conflicting results.However,none have investigated growth hormone(GH)which is related to IGF-I via negative feedback.AIM To investigate the relationship between serum levels of IGF-I and GH,and the occurrence of delirium.METHODS Prospective,longitudinal,observational study.Consecutive elderly inpatients(aged 70+),were assessed twice weekly with Montreal cognitive assessment(MoCA),Confusion assessment method(CAM),Acute Physiology and Chronic Health Evaluation II.Delirium was defined using CAM.Previous history of dementia was evaluated with the Informant Questionnaire on Cognitive Decline in the Elderly.IGF-I and GH levels were estimated with the ELISA method.Generalized estimating equations(GEE)model was applied for the first five assessments to analyze those longitudinal data.RESULTS The sample consisted of 198 participants(mean age 80.63±6.81;range 70-97).Of these 92(46.5%)were females.Eighty six(43.4%)were identified with a history of dementia.Incident or prevalent delirium during hospitalisation was identified with CAM in 40 participants(20.2%).Evaluation of missing values with Little's MCAR test indicated that they were missing completely at random(MCARχ2=12.24,u:9,P=0.20).Using GEE for the analysis we found that low MoCA scores,low levels of IGF-I and high levels of GH were significantly associated with any delirium(prevalence,incident,or fluctuating,during the study period(Waldχ2=12.231;u:1,P<0.001,Waldχ2=7.196,u:1,P=0.007,Waldχ2=6.210;:u:1,P=0.013 respectively).CONCLUSION The results show that low levels of IGF-I,high levels of GH and low scores in cognition are independently associated with the occurrence of any delirium during the hospitalisation of medically ill older people.The results of the study supports the hypothesis that deficits in the immunoreactivity of the brain(low cerebral reserve)may be associated with delirium.

乳腺癌组织中IGF-IR、SUSD3的表达及其临床意义

目的探讨胰岛素样生长因子-I受体(IGF-IR)和SUSD3在乳腺癌组织中的表达情况,分析两者与临床病理特征的关系及其两者间的相关性。方法采用Max VisionTM免疫组化法检测100例乳腺癌组织和对应癌旁组织中IGF-IR、SUSD3的表达,并分析其与乳腺癌临床病理特征的关系。结果 IGF-IR在乳腺癌和癌旁组织中的阳性表达率分别为86.0%和3.0%(P<0.05),SUSD3在乳腺癌和癌旁组织中的阳性表达率分别为78.0%和2.0%(P<0.05)。乳腺癌组织中IGF-IR和SUSD3的表达与ER水平和病理类型有关(P<0.05),而与年龄、HER-2表达、Ki-67表达和分期均无关(P>0.05)。IGF-IR和SUSD3在乳腺癌组织中的表达呈正相关(r=0.553,P<0.01)。结论 IGF-IR、SUSD3可能与乳腺癌的发生、发展有关,与ER联合检测对判断乳腺癌预后和指导术后辅助治疗有重要意义。

五岳抗甲丸辅助治疗Graves病的疗效及对血清IGF-I水平的影响

目的探讨五岳抗甲丸辅助治疗Graves病（以下简称GD）的疗效及作用机制。方法将58例初诊GD患者随机分为观察组与对照组各29例，两组均口服他巴唑5-15mg或丙基硫氧嘧啶50-150mg，3次／d，观察组在此基础上加服五岳抗甲丸3-5g，3次／d。两组均连续用药3个月。观察两组治疗前后甲状腺体积及血清胰岛素样生长因子-I（IGF-I）水平变化，并行相关分析。结果两组治疗后甲状腺体积均明显缩小，血清IGF-I水平均下降，但观察组下降更明显（P〈0．01）。甲状腺体积与血清IGF-I水平呈正相关（r=0．57，P〈0．01）。结论五岳抗甲丸治疗GD效果确切，其机制可能为降低血清IGF-I的水平。

Expression of albumin, IGF-1, IGFBP-3 in tumor tissues and adjacent non-tumor tissues of hepatocellular carcinoma patients with cirrhosis

AIM： To explore the expression of albumin （ALB）, insulinlike growth factor （IGF）-I, and insulin-like growth factor binding protein （IGFBP）-3 in tumor tissues and adjacent non-tumor tissues of hepatocellular carcinoma （HCC） patients with cirrhosis.METHODS： Twenty-four HCC patients with cirrhosis who underwent hepatectomy were studied. ALB mRNA, IGF-1 mRNA, and IGFBP-3 mRNA in liver tissues （including tumor tissues and adjacent non-tumor tissues） were detected by reverse transcriptase-polymerase chain reaction（RT-PCR）. Liver Ki67 immunohistochemistry staining was studied. At the same time, 12 patients with cholelithiasis or liver angioma who underwent operation were segregated as normal control.RESULTS： In HCC patients with cirrhosis, hepatic ALB mRNA, IGF-1 mRNA, and IGFBP-3 mRNA of tumor tissues or adjacent non-tumor tissues were lower than the normal liver tissues, while in tumor tissues, hepatic ALB mRNA and IGFBP-3 mRNA were lower, hepatic IGF-1 mRNA was higher than in adjacent non-tumor tissues. Liver Ki67 labeling index （Ki67 LI） in tumor tissues or adjacent nontumor tissues were higher than that in the normal liver tissues, while in tumor tissues it was higher than that in adjacent non-tumor tissues.CONCLUSION： Imbalance of IGF-1 and IGFBP-3 may play a role in hepatocarcinogenesis and tumor development of liver cirrhosis patients.

CEA and AFP expression in human hepatoma cells transfected with antisense IGF-I gene

IM To determine whether antisense insulinlike growth factorI(IGFI) gene can modulate CEA and AFP expression in human hepatoma cells (HepG2).METHODS Transfection of HepG2 cells was accomplished using Lipofectin reagent. Northern blot analysis confirmed the antisense IGFI RNA of the transfected cells. CEA and AFP levels were measured using radioimmunoassay.RESULTS Human hepatoma cell lines (HepG2) were transfected with antisense IGFI gene. Northern blot analysis confirmed that antisense IGFI RNA was expressed in the transfected cells. The effect of antisense IGFI gene on CEA and AFP expression was demonstrated by the fact that the CEA and AFP levels in the supernatant of transfected cell culture were significantly lower as compared with the parent cells, 〔CEA 70μg/L±076μg/L and 329μg/L±180μg/L (P<005) and AFP 5363μg/L±602μg/L and 90μg/L±526μg/L (P<001), respectively〕.CONCLUSION The malignant potentiality of the transfected cells was partially suppressed. Antisense IGFI gene can modulate the expression of CEA and AFP in human hepatoma cell lines (HepG2).

Effects of insulin, insulin-like growth factor-I and -II on proliferation and intracellular signaling in endometrial carcinoma cells with different expression levels of insulin receptor isoform A

Background Hyperinsulinemia, insulin-like growth factor （IGF）-I and -Ⅱ （IGF-Ⅱ） are associated with increased risk of endometrial carcinoma. Insulin receptor isoform A （IR-A） is more frequently expressed in endombtrial carcinoma than in normal endometrial tissues. To better understand their roles in endometrial carcinoma, we investigated the effects of insulin, IGF-I, and IGF-II in endometrial carcinomas cells with different IR-A expression levels. Methods To explore the role of IR-A in mediating the activity of IGF-I, IGF-II, and insulin, we investigate the cellular proliferation of endometrial carcinoma cell lines RL95-2 and RL95-2-1R-A by MTS assays. Then we examined the protein kinase Akt phosphorylation and extracellular signal-regulated kinase （ERK） 1/2 phosphorylation in both cell lines by Western blotting. The effect of IGF-II and AG1024 on cell cycle progression and apoptosis was assessed by fiowcytometry. To examine whether the effects of IGFs were mediated by IR-A, we blocked IGF-I receptor （IGF-IR） in both cell lines using AG1024, an IGF-IR-specific inhibitor. Results IGF-I and IGF-II significantly enhanced proliferation of both cell lines （P 〈0.05）. By contrast, insulin significantly increased proliferation of RL95-2-1R-A cells only （P 〈0.05）. IGF-I and IGF-II significantly increased pAkt levels in RL95-2 cells and pERK1/2 levels in RL95-2-1R-A cells （all, P 〈0.05）. Insulin increased pERK1/2 levels in RL95-2-1R-A cells only （P 〈0.05）. LY294002 and PD98059 inhibited the specific signaling activities and cellular proliferation. After AG1024 pretreatment, neither IGF-I nor IGF-II affected pAkt levels in RL95-2 cells. IGF-II, but not IGF-I, increased pERK1/2 levels in RL95-2-1R-A cells. After AG1024 pretreatment, the proliferation rate and DNA content corresponding to the S phase increased and apoptosis decreased significantly in IGF-II-treated RL95-2-1R-A cells only （P 〈0.05）. Conclusions The proliferation effect of insulin is mediated by IR-A. When IR-A dominates in a cell line, IGF-II activated cell proliferation mainly through the ERKI/2 pathway. On the other hand, IGF-II activated cell proliferation mainly through the Akt pathway. IR-A can at least partly mediate the proliferative and anti-apoptotic effects of IGF-II through the ERKI/2 pathway.

Effects of dietary genistein on GH/IGF-I axis of Nile tilapia Oreochromis niloticus

There is considerable concern that isoflavones,such as genistein in fish feed composed of soybean protein,affects somatic growth in fish.Our previous works demonstrated that 30 and 300 μg/g dietary genistein had no significant effect on growth performance in Nile tilapia(Oreochromis niloticus),but the higher level of genistein(3 000 μg/g) significantly depressed growth.This study was conducted to further examine the effects of dietary genistein on the endocrine disruption on growth hormone/insulin-like growth factor-I(GH/IGF-I) axis in Nile tilapia(O.niloticus).Juvenile fish were fed by hand twice daily to satiation with one of four isonitrogenous and isoenergetic diets,each containing either 0,30,300 or3 000 μg/g genistein.Following an 8-week feeding period,plasma GH and IGF-I levels were investigated by radioimmunoassay and gene expression levels of gh,ghrelin,gnrhs,ghr,npy,npyrs,pacap,ghrs,igf-I,igf-Ir,and igfbp3 were examined by real-time PCR.The results show that no significant change in plasma GH and IGF-I levels in fish fed with diets containing 30 μg/gand 300 μg/g genistein.mRNA expression of genes along the GH/IGF-I axis remained unaffected,except for igf-Ir,which was stimulated by the 300 μg/g genistein diet.While in fish fed the 3 000 μg/g genistein diet,the plasma GH and IGF-I levels decreased,and mRNA expression of gh,ghr2,npyr1,igf-I,and igf-Ir were also significantly depressed.In contrast,npy and igfbp3 mRNA expression were enhanced.This study provides convincing evidence for growth impediment by genistein by disturbing the GH/IGF-I axis in Nile tilapia O.niloticus.

The Relationships between Serum Concentration of IGF-I and Left Ventricular Function as well as Coronary Collateral Circulation in Patients with Coronary Artery Disease

Objective To investigate therelationships between serum concentration of insulin -like growth factor - I (IGF-I) and left ventricular function as well as coronary collateral circulation in patients with coronary artery disease (CAD) . Methods In 41 patients with CAD and 15 control subjects without CAD, the concentrations of serum IGF - I were measured using radioimmunoassay. The relationships between the concentration of serum IGF - I and Leaman coronary artery score, Rentrop grade of coronary collateral circulation, left ventricular ejection fraction (LVEF) as well as left ventricular wall motion Cortina score were assessed. Results 1. There was no significant difference in the mean level of serum IGF -I between the CAD group and the control group (107. 92±44.74 ng/ml vs 113.05 ±33. 65 ng/ml, P> 0. 05), but the IGF - I concentrations in the subgroup with collateral circulation were significantly greater than that in the control group (147. 33 ±29. 92 ng/ml vs 113. 05±33. 65 ng/ml, P < 0. 01) or in the subgroup without collateral circulation (147. 33 ±29. 92 ng/ml vs 80. 01±29. 75 ng/ml , P < 0. 01). 2. The serum concentration of IGF -I had no significant correlation to the Leaman coronary artery score. 3. The serum level of IGF -I had significantly positive correlation to both LVEF ( r = 0. 45, P < 0. 001) and the Rentrop grade of coronary collateral circulation ( r = 0. 74, P < 0. 001), and was negatively related to the left ventricular wall motion Cortina score (r = -0. 53, P < 0. 001). 4. The Leaman coronary artery score had no significant correlation to the Rentrop grade of coronary collateral circulation. 5. The Leaman coronary artery score was related to neither the LVEF nor the Cortina score in the whole CAD group. In the subgroup without coronary collateral circulation, however, the Leaman score had significantly negative correlation to LVEF ( r = - 0. 46, P < 0. 05) and positive correlation to the Cortina score (r = 0. 47, P < 0. 05) . Conclusions The serum concentration of IGF -I was associated with both left ventricular function and coronary collateral circulation in patients with CAD. IGF -I may play a role in promoting coronary collateral circulation and in protecting left ventricular function in patients with coronary artery disease.

Arginine Intake and Carbohydrate to Lipid Ratios Affect Gene Expression of Anabolic Hormones in Largemouth Bass, Micropterus Sahnoides

Nutritional factors influence regulation of growth hormone （GH）, insulin-like growth factor-Ⅰ （IGF-Ⅰ） and insulin （INS） in fish. But so far there are no published studies describing how single indispensable amino acids and different carbohydrate to lipid ratios influence those systems. Therefore, the present study aimed to evaluate whether arginine （Arg） intake and carbohydrate to lipid ratios would affect expression of GH, IGF-Ⅰ and INS in largemouth bass.

PI-3K/Akt/GSK-3p signaling cascades stimulated by insulin like growth factor-Ⅰcontribute to multiple myeloma cells proliferation and survival

Multiple myeloma is characterized by the accumulation of malignant plasma cells in thebone marrow. Significant progress in molecular mechanisms of signaling pathways underlying the survival and/or proliferation of these cells has been achieved. Interleukin 6 （IL-6） is an important cytokine leading to multiple myeloma （MM） cells growth and survival. However, some MM cells isolated from MM patients are poorly responsive to IL-6 stimulation or IL-6 independent. This phenomenon raises the possibility that other growth factors may also be involved in the development of MM. Insulin like growth factor-I （IGF-I） plays an important role in the proliferation of a variety of cell types, in the development and growth of multiple tumors and in the prevention of apoptosis. IGF-I has recently been reported to play such a role in stimulating the MM cells growth, it even induces MM cells proliferation in IL-6 dependent cells, yet the detailed signaling components triggered by IGF-I have not been completely clarified. Thus, the present study are to address the signaling cascades triggered by IGF-I in MM cells.

Expression of hIGF-I in the silk glands of transgenic silkworms and in transformed silkworm cells

To express human insulin-like growth factor-I (hIGF-I) in transformed Bombyx mori cultured cells and silk glands, the transgenic vector pigA3GFP-hIGF-ie-neo was constructed with a neomycin resistance gene driven by the baculovirus ie-1 promoter, and with the hIGF-I gene under the control of the silkworm sericin promoter Ser-1. The stably transformed BmN cells expressing hIGF-I were selected by using the antibiotic G418 at a final concentration of 700-800 μg/mL after the BmN cells were transfected with the piggyBac vector and the helper plasmid. The specific band of hIGF-I was detected in the transformed cells by Western blot. The expression level of hIGF-I, determined by ELISA, was about 7800 pg in 5×105 cells. Analysis of the chromosomal insertion sites by inverse PCR showed that exogenous DNA could be inserted into the cell genome randomly or at TTAA target sequence specifically for piggyBac element transposition. The transgenic vector pigA3GFP-hIGF-ie-neo was transferred into the eggs using sperm-mediated gene transfer. Finally, two transgenic silkworms were obtained after screening for the neo and gfp genes and verified by PCR and dot hybridization. The expression level of hIGF-I determined by ELISA was about 2440 pg/g of silk gland of the transgenic silkworms of the G1 generation.