[Thoughts on the reform of preventive medicine education in the context of new medicine].

Talent training is the core and foundation of public health system construction. Shortage of talents in the field of disease prevention and public health exposed by COVID-19 pandemic highlights the importance of developing preventive medical education. This article analyzes the challenges of medical education in the dilemma of "separation of medical treatment and prevention", and the new requirements for preventive medical education in the construction of New Medicine under the Healthy China strategy. Four aspects including stepping up the resource allocation and investment, educating responsible public health professionals, the education of all medical students who implement the core competence of public health, and the establishment of a continuing education system for preventive medicine have been considered. A series of specific suggestions are put forward including the establishment of a full-chain closed-loop research system to support the cultivation of top-notch innovative public health talents, strengthening the assessment of core public health capabilities for clinical medical professional admission, formulating a "medical and preventive integration" training program for primary health personnel, and implementing "combination of peace and war" public health personnel reserve system, with the purpose of providing reference for the reform and development of preventive medical education in China.

[Data management and quality control strategies for population based cohort study].

Large-scale cohort study has unique advantages in the field of etiology research for its large sample size a multi-time point data, but it also brings great difficulty in data management and quality control at the same time. Recently, China has initiated a number of large-scale population cohort studies, posing enormous challenges to the management and quality control of related cohort data. This paper summarizes the existing experience and consensus in the field of cohort study in China from the characteristics of the cohort data, aiming at the types and main forms of the four main sources of questionnaire data, clinical diagnosis and treatment data, biological sample detection data and observation outcome data, from the data storage, circulation and transmission work.The contents and methods of queue data management are comprehensively summarized. Corresponding data quality control strategies are advised in the questionnaire evaluation, data logic verification, survey object sampling and multi-database review, etc. The goal of this review is to provide guidance for the management of data and the formulation of quality control strategies in the cohort study in China.

[Mediation effect of smoking and healthy diet score on the association between educational level and the risk of lung cancer incidence].

Objective: To evaluate the possible mediation effect of smoking and healthy diet score on the association between educational level and the risk of lung cancer incidence. Methods: After excluding individuals with missing educational levels and cancer information at baseline, 446 772 participants in the UK Biobank (UKB) prospective cohort study were included. Cox regression models were used to investigate the associations of educational level and smoking and healthy diet score with the incidence of lung cancer. Mediating effect analysis was conducted to analyze the mediating effect of smoking and healthy diet score on the correlation between educational level and lung cancer. Results: During a median follow-up of 7.13 years, 1 994 new- onset lung cancer cases were observed. Per 1 standard deviation (5 years) increase in educational level was associated with a 12% lower risk of lung cancer (HR=0.88, 95%CI: 0.84-0.92). The corresponding level 1-5 in the International Standard Classification for Education (ISCED) were mapped to UKB self-report highest qualification to estimate the educational level. A higher rank means a higher educational level. Compared with level ISCED-1, the HR(95%CI) of level ISCED-2, ISCED-3, ISCED-4 and ISCED-5 were respectively 0.83 (0.72-0.94), 0.67 (0.53-0.85), 0.76 (0.65-0.89) and 0.72 (0.64-0.80) for lung cancer. Education years were negatively correlated with smoking, with ß coefficients (95%CI) being -0.079 (-0.081- -0.077), but positively correlated with healthy diet score (ß=0.042, 95%CI: 0.039-0.045). Analysis of mediating effect indicated that the association of educational level with lung cancer risk was mediated by smoking and healthy diet score, the proportions of mediating effect were 38.952% (95%CI: 31.802%-51.659%) and 1.784% (95%CI: 0.405%-3.713%), respectively. Conclusion: Smoking and healthy diet score might mediate the effect of educational level on the incidence of lung cancer, indicating that improving the level of education can reduce the risk of lung cancer by changing lifestyles such as smoking and diet.

Polymorphisms in toll-like receptor 4 gene are associated with asthma severity but not susceptibility in a Chinese Han population.

BACKGROUND AND OBJECTIVES: The toll-like receptor 4 (TLR4) gene links human innate immunity and adaptive immunity via bacterial endotoxin recognition, and plays a considerable role in the pathogenesis of asthma. The effects of the genetic variants of TLR4 on asthma are still largely unknown. This study aimed to evaluate the effects of TLR4 polymorphisms on asthma risk and asthma-related phenotypes in a Chinese Han population. METHODS: We consecutively recruited 318 unrelated adult asthmatic patients and 352 healthy volunteers. Four tagging single nucleotide polymorphisms (SNPs) in the TLR4 gene were detected using GenomeLab SNPstream or TaqMans Genotyping. We conducted case-control and case-only studies to investigate the association between the selected tagging SNPs in TLR4 and asthma and asthma-related phenotypes. RESULTS: We found no evidence to support a significant association between TLR4 SNPs and asthma susceptibility. However, our results revealed that the TT homozygote of rs1927914 was associated with lower forced expiratory volume in the first second (percent predicted) in asthmatic patients. An evidently positive association was found between asthma severity and both the TT genotype of rs1927914 and the GG genotype of rs10983755 and rs1927907 (P = .024, P = .009, and P = .013, respectively), indicating that the C allele of rs1927914 and the A allele of rs10983755 and rs1927907 have a protective effect on asthma severity. CONCLUSION: TLR4 polymorphisms do not contribute to asthma susceptibility but they may influence the severity of asthma.

[Epidemiological research in the big data era: opportunities, challenges and prospectives].

Recent years with the rapid progress in high-throughput omics techniques, the accumulation of population cohorts and biobanks, great advances in internet and information technology, and the emerging tools for big data utilization, health care big data provide abundant data resources and broad research platforms for epidemiological research. We aimed to review the opportunities and challenges of epidemiological research in the era of big data, and explore the future development of epidemiology. Epidemiology should seize the opportunities, open up new directions, develop new methods, and promote the translation of research results into public health and clinical medicine, which will eventually realize the vision of "Healthy China".

[Polygenic risk score in personalized screening of lung cancer: a prospective cohort study in Chinese].

Objective: To explore how to personalize lung cancer screening programs for prevention in Chinese populations based on individual genetic risk score. Methods: We constructed the lung cancer polygenic genetic risk score (PRS-19) based on the 19 previously published genetic variations, using 100 615 participants with genotyping data from the China Kadoorie Biobank (CKB). Using the 5-year absolute risk of lung cancer in a population (55 years old with at least 30-pack-year history of smoking) as reference, the trend of 5-year absolute risk in different genetic risk groups was calculated in smokers and non-smokers, respectively. Distribution curves of 5-year absolute risk were also described to determine the theoretical age or smoking dose when different genetic risk groups reached the reference values. Given the overall findings, the specific start age for lung cancer screening were suggested for different genetic risk groups. Results: The 5-year absolute risk of lung cancer was 0.67% in 55-year-old smokers with 30 packs per year in the CKB. Among smokers, 5-year absolute risk of participants increased as the genetic risk increased. Hence, it was recommended that people at high genetic risk should start screening earlier. For the highest genetic risk populations (the top 1% of PRS), the start age might be changed to 50 years old. If the start age remained at 55-year-old, the smoking dose should be set lowered in high genetic risk populations. For the highest genetic risk populations, they should be included in lung cancer screening regardless of the cumulative smoking exposure. Among nonsmokers, it was also valuable to screen people with high genetic risk, considering the start age of 62 for the highest genetic risk populations and 74 for the lowest genetic risk populations (the bottom 5% of PRS). Conclusions: PRS-19 can be effectively used in developing lung cancer screening program for individualized prevention in China. For smokers with high genetic risk, the recommended starting age and smoking dose could be lowered for lung cancer screening, and non-smokers with high genetic risk could also be included in the screening programs.

[Quality control and measures of China National Birth Cohort].

Birth cohort is an effective method to explore the relationship between various prepregnant and pregnant exposures and the health of fetuses, infants and young children. It is a long construction period to build a birth cohort and the quality of research may be affected by many factors. This paper reviews the quality assurance and quality control measures in the process of China National Birth Cohort (CNBC), and summarizes the construction experience. We aim to provide experience for related cohort studies, which could improve the quality of cohort studies through removing the impact of related factors. CNBC adopted a series of measures to ensure the quality of research in the top-level design of quality assurance, including screening research center, developing member management system, formulating standard operating procedures and training staff by it. In terms of quality control, it includes real-time, timely and timing quality control for the process of data generation, full-cycle quality control for biological sample collection, processing, storage and comprehensive three-dimensional quality control for staff training, supervision and quantitative assessment.

[Application of cloud-based information platform in China National Birth Cohort].

Birth cohort is an important observational study which can continuously and dynamically collect the exposure changes and health outcomes from gametophyte development to adolescence and even old age. However, because of its complex design and difficult implementation, how to construct birth cohort with high quality and high efficiency is the main difficulty faced by epidemiologists at home and abroad. In 2016, China National Birth Cohort was officially launched. The network and information technology were used to explore, and a set of "cloud-based information platform" was established to support this queue construction, containing 16 units in China. After four years of development, the platform has formed a complete set of programs about the construction of cohort information platform, which including recruitment and follow-up management of participants, real-time data interaction, queue quality control, multi-level authority management and function division. The relevant design framework and functional elements provide the references to the future information construction of large-scale birth cohort and even population-based research in China.

[Association between polygenic risk score and age at onset of gastric cancer].

Objective: To explore the association between polygenic risk score (PRS) and age at onset and early-onset risk of gastric cancer (GC). Methods: Gastric cancer cases from existing genome-wide association study were included, and 112 single nucleotide polymorphisms associated with GC risk were used to derive individual PRS. Analysis of variance and Pearson correlation test was used to depict the relationship between PRS and GC onset age. Cases diagnosed before 50 years old were defined as early-onset gastric cancer. Cox proportional hazard model was used to test the association between PRS and early-onset GC risk with early-onset age as the timescale and low genetic risk (PRS ≤20%) as the reference group. Results: A total of 8 629 cases, including 6 284 males (72.82%) and 2 345 females (27.18%), were included, and the mean age was (60.61±10.80) years old. The PRS was negatively correlated with age of GC onset (r=-0.05, P<0.001). The mean age of gastric cancer cases with low, intermediate, and high genetic risk were (61.68±10.33), (60.53±10.79), (59.80±11.20), respectively. PRS was significantly associated with the risk of early-onset GC in a dose-response manner (intermediate genetic risk: HR=1.19, 95%CI: 1.03-1.39, P=0.022; high genetic risk: HR=1.44, 95%CI: 1.20-1.71, P<0.001). Conclusions: PRS may contribute to the risk of both GC and early-onset GC. PRS can be used as a measurable indicator for risk prediction for occurrence and early-onset of GC.

[Profile of China National Birth Cohort].

With the rapid changes in lifestyle, natural and social environment, the reproductive health status of couples in childbearing age continues to decline, and long-term outcomes of the rapidly increasing offspring conceived by assisted reproductive technology (ART) needs to be evaluated urgently. Therefore, the focus of research now needs to be extended from death and severe diseases to full life cycle and full disease spectrum. In order to meet the demand for such research, we launched the China National Birth Cohort (CNBC) study, an ongoing prospective and longitudinal study aiming to recruit 30 000 families underwent ART and 30 000 families with spontaneous pregnancies. Long-term follow-up programs will be conducted for both spouses and their offspring. Data of couples and their offspring, such as environmental exposure, reproductive history, psychological and behavioral status, will be collected during follow-up. Peripheral blood, urine, umbilical blood, follicular fluid, semen were also collected at different follow-up nodes. Based on high-quality data and biological samples, CNBC will play an extremely important supporting role and have a far-reaching impact on maternal and children's health care and reproductive health in China. This paper is exactly a brief introduction to the construction and basic design of CNBC.

[Baseline characteristics of the participants of China National Birth Cohort].

Objective: To explore the effects of environmental, genetic factors as well as the interactions in early life on the short-term and long-term health of offspring and to systematically evaluate the pregnancy outcomes and health of offspring after birth between families with assisted reproductive technology (ART) conception and families with spontaneous conception. Methods: The China National Birth Cohort (CNBC), a multicenter prospective birth cohort study, includes both families with ART conception and families with spontaneous conception. Since 2016, CNBC has recruited families from 24 hospitals located in 12 provinces, municipalities and autonomous regions throughout China. Information and biospecimens were collected before ART treatment, embryo transfer, at early, second, third trimester and delivery, and at 42 days, 6, 12 and 36 months after birth. Results: By June 2020, CNBC had included 27 044 families with ART conception and 29 589 families with spontaneous conception. The majority of the participants are urban residents. Among the families with ART conception, 65.5% of the men and 63.7% of the women had college degrees or higher. The mean age distribution of men and women was (33.83±5.52) and (32.38±4.67) years. 83.2% of women were primiparas, and the prevalence rates of current regular smokers and current alcohol drinkers were 0.8% and 2.1% in women. Among the families with spontaneous conception, 81.5% of the men and 86.5% of the women had college degrees or higher. The mean age distribution of men and women was (32.06±5.09) and (30.40±4.27) years. 67.2% of women were primiparas, and the prevalence rates of current regular smokers and current alcohol drinkers were 0.1% and 2.2% in women. The baseline characteristics were different between the families with ART conception and spontaneous conception in different regions. Conclusion: CNBC provides a powerful and rich resource in studying the impact of genetic, environmental factors and interactions in early life and ART treatment on the health of offspring after birth.

[The Autism Spectrum Disorder Cohort-the sub-cohort of China National Birth Cohort].

Autism spectrum disorder (ASD), a representative disease of children's neurodevelopmental disorders, brings huge pressure and financial burden to families and society. It is of great significance to explore its etiology and pathogenesis. Therefore, we established an ASD Cohort based on the existing China National Birth Cohort (CNBC), which applied parallel design to recruit and follow up families who achieved pregnancy after receiving assisted reproductive technologies (ART) and families with spontaneous conception. The main aims of this study are to compare the incidence of ASD among children born after ART with those born under spontaneous pregnancy, and to evaluate the impact of ART on the neurobehavioral development of offspring. Additionally, with a variety of clinical and behavioral related information collected during pregnancy and at early life of offspring, we are able to investigate the risk factors associated with ASD comprehensively. This article briefly introduces the objectives, contents, preliminary progress, strength and limitations, as well as further prospects of the ASD cohort study, mainly focusing on the overall design and current progress.

[A sub-cohort study design of the maternal and infant microbes in China National Birth Cohort].

The importance of gut microbes to human health has gradually attracted attention. With the use of animal models, it has been revealed that maternal microbes during pregnancy could influence their children's health outcomes through shaping their microbial composition and regulating the development of their metabolic and immune system. However, the physiological mechanism of the human body is more complex and is affected by the interaction of multiple factors. The research results obtained from animal models are often inconsistent with human studies. At present, the influence of maternal intestinal microbes during pregnancy on the microbial colonization in their offspring and on a series of children's health outcomes is still unclear. Establishing a sub-cohort to detect the microbiome of the women across pregnancy and of their offspring, and further to integrate with variety of environmental and behavioral exposures can better provide reliable support for the research on the mechanism of children's health and diseases. This paper briefly introduces the research objectives, content, progress, strength and limitations of the sub-cohort study.

Polymorphisms in the toll-like receptor 2 subfamily and risk of asthma: a case-control analysis in a Chinese population.

BACKGROUND AND OBJECTIVE: Cell activation through toll-like receptors (TLRs) has robust bipolar effects on host immunity and the pathogenesis of asthma. The TLR2 subfamily is a pivotal member of the TLR family. We sought to determine whether mutations in TLR2 subfamily genes affect the risk of asthma. METHODS: A total of 318 asthmatic patients and 352 nonasthmatic controls were recruited. Eight single-nucleotide polymorphisms in TLR2 subfamily genes were detected using GenomeLab SNPstream (Beckman Coulter, Fullerton, California, USA). RESULTS: We found that patients with the TLR2/rs7656411 TT variant homozygote had a significantly reduced risk of asthma when compared with those with the GG wild-type homozygote (adjusted odds ratio [OR], 0.63; 95% confidence interval (CI], 0.41-0.98; P = .036). Furthermore, a positive association was observed between the T allele of rs2381289 in TLR6 and allergic rhinitis in asthma (OR, 1.79; 95% CI, 1.10-2.91; P = .025), while the A allele of rs11466651 in TLRIO was negatively associated with allergic rhinitis (OR, 0.49; 95% CI, 0.26-0.95; P = .046). CONCLUSION: Our results indicate that a genetic variant in the TLR2 subfamily may play a role in susceptibility to asthma.

[Study on genetic structure differences and adjustment strategies in different areas of China].

Objective: To describe the genetic structure of populations in different areas of China, and explore the effects of different strategies to control the confounding factors of the genetic structure in cohort studies. Methods: By using the genome-wide association study (GWAS) on data of 4 500 samples from 10 areas of the China Kadoorie Biobank (CKB), we performed principal components analysis to extract the first and second principal components of the samples for the component two-dimensional diagram generation, and then compared them with the source of sample area to analyze the characteristics of genetic structure of the samples from different areas of China. Based on the CKB cohort data, a simulation data set with cluster sample characteristics such as genetic structure differences and extensive kinship was generated; and the effects of different analysis strategies including traditional analysis scheme and mixed linear model on the inflation factor (λ) were evaluated. Results: There were significant genetic structure differences in different areas of China. Distribution of the principal components of the population genetic structure was basically consistent with the geographical distribution of the project area. The first principal component corresponds to the latitude of different areas, and the second principal component corresponds to the longitude of different areas. The generated simulation data showed high false positive rate (λ=1.16), even if the principal components of the genetic structure was adjusted or the area specific subgroup analysis was performed, λ could not be effectively controlled (λ>1.05); while, by using a mixed linear model adjusting for the kinship matrix, λ was effectively controlled regardless of whether the genetic structure principal component was further adjusted (λ=0.99). Conclusions: There were large differences in genetic structure among populations in different areas of China. In molecular epidemiology studies, bias caused by population genetic structure needs to be carefully treated. For large cohort data with complex genetic structure and extensive kinship, it is necessary to use a mixed linear model for association analysis.

Induction of glutathione S-transferase hGST 5.8 is an early response to oxidative stress in RPE cells.

PURPOSE: To delineate the role of the glutathione S-transferase (GST) isozyme hGST 5.8 in protection mechanisms against oxidative stress, the effect of low-level transient exposure of H2O2 to retinal pigmented epithelial (RPE) cells on hGST 5.8 and other enzymes involved in defense against oxidative stress was examined. METHODS: Cultured human RPE cells were exposed to 50 microM H2O2 for 20 minutes. Subsequently, the cells were washed and resuspended in the culture media. The cells were pelleted and lysed, and the levels of lipid peroxidation products including thiobarbituric acid-reactive substances (TBARS), glutathione (GSH), glutathione peroxidase (GPX), glucose 6-phosphate dehydrogenase, glutathione reductase, GST, catalase (CAT), and superoxide dismutase (SOD) were determined and compared with levels in control cells. Total GSTs were purified by GSH-affinity chromatography, and the isozymes were separated by isoelectric focusing, characterized, and quantitated. hGST 5.8 was quantitated by an immunologic method as well as by determining activity toward its preferred substrate, 4-hydroxynonenal (4-HNE). Kinetic constants of hGST 5.8 purified from H2O2-treated cells were also determined and compared with those of control cells. RESULTS: Exposure of RPE cells to 50 microM H2O2 for 20 minutes showed a significant increase in TBARS (1.8-fold) and gamma-glutamyl cysteine synthetase (gamma-GCS) activity (1.6-fold). A significant increase (1.2-fold) was also observed in GPX activity toward cumene hydroperoxide, but CAT and SOD activities remained unchanged. There was no significant increase in GST activity toward 1-chloro-2, 4-dinitrobenzene but GST activity toward 4-HNE was increased by 1.4- to 1.8-fold. The increase in GST activity toward 4-HNE was associated with a 2.8-fold increase in protein of the isozyme hGST 5.8, which uses 4-HNE as the preferred substrate. CONCLUSIONS: Results of these studies show that the induction of hGST 5.8, which is involved in the detoxification of the lipid peroxidation products 4-HNE and hydroperoxides, may be an early adaptive response of RPE cells exposed to low levels of transient oxidative stress. It is suggested that this isozyme may be crucial for protecting the RPE from low levels of chronic oxidative stress. Observed increases in GPX and gamma-GCS activities are consistent with this idea, because GPX activity is also expressed by hGST 5.8, and gamma-GCS is the rate-limiting enzyme in biosynthesis of GSH, the substrate for hGST 5.8.

The effect of bombesin-related peptides on the phagocytic function of mouse phagocytes in vitro.

Bombesin (BBS) at doses of 0.1, 1.0, 10.0 and 100.0 nM stimulated chemiluminescence (CL) production by phagocytic cells (monocytes, macrophages and polymorphonuclear leucocytes) in mice in the presence of ZAP (opsonized zymosan particles containing luminol). These data suggest that BBS increased the phagocytic function of mouse phagocytes. BBS-related peptides, gastrin-releasing peptides (GRP)-27, GRP-14, GRP-10 and neuromedin B, also induced similar CL responses compared with BBS. The CL response elicited by BBS was depressed dramatically by various concentrations of EGTA (a Ca++ chelator), indicating that a Ca++ pathway may play a key role in the BBS-stimulated CL response.

Stimulation of neutrophil leukocyte chemotaxis by a cloned cytolytic enterotoxin of Aeromonas hydrophila.

A cytolytic enterotoxin produced by Aeromonas hydrophila, isolate SSU, has been cloned in our laboratory. This enterotoxin lysed rabbit red blood cells, destroyed Chinese hamster ovary cells, caused fluid secretion in rat ligated ileal loops, inhibited the phagocytic function of mouse phagocytes, and was lethal to mice when injected intravenously. In this study, the effect of this cytolytic enterotoxin on the chemotaxis of human leukocytes (cell line RPMI 1788) was examined. This toxin, at concentrations from 92.5 to 370 ng/ml, significantly stimulated the chemotactic activity of human leukocytes in a dose-dependent fashion. The stimulation of leukocyte chemotaxis elicited by cytolytic enterotoxin was abolished when the toxin was neutralized, heated, or exposed to low pH values. This stimulatory effect also was inhibited by various concentrations of pertussis toxin. These results demonstrated that cytolytic enterotoxin may stimulate increased chemotaxis of human leukocytes, and suggest that human leukocytes may possess cytolytic enterotoxin receptors which may be coupled to pertussis toxin-sensitive G-protein.

Insulin-like growth factors enhance phagocytosis by human neutrophils in vitro.

Polymorphonuclear neutrophils (PMNs) were isolated from human blood, and PMN phagocytosis was assessed by measuring the chemiluminescence (CL) response in the presence of ZAP (opsonized zymosin particles containing luminol). The administration of 6.5 nM of insulin-like growth factor I (IGF-I), des(1-3)-IGF-I, IGF-II or insulin to PMNs for 20 min resulted in significant increases of the CL response for all test preparations. Des(1-3)-IGF-I, a truncated IGF-I with low affinity binding to IGF binding proteins (IGFBPs), was the most potent CL stimulator. The CL production evoked by 6.5 nM of des(1-3)-IGF-I was inhibited significantly by both 0.25 and 1.0 nM of EGTA (Ca2+ chelator), or 10 microM nifedipine (Ca2+ channel inhibitor), pertussis toxin (0.05 and 1.0 micrograms/ml) or cholera toxin (5 micrograms/ml). These results suggest that IGF-I and its homologues are potent stimulators of phagocytosis and that this action is modulated by IGFBP, and may require extracellular Ca2+ and/or IGF-I receptor G-protein coupling.

Insulin-like growth factor-II expression in carcinoma in colon cell lines: implications for autocrine actions.

BACKGROUND: In the gastrointestinal tract, insulin-like growth factor-II (IGF-II) messenger RNA (mRNA) is localized mainly in mesenchymal cells, and is more abundant in the fetus than in the adult. The purposes of this study are to characterize the gene expression of IGF-II at the mRNA and protein level in seven different epithelial cell lines derived from colon carcinomas and to determine the action of IGF-II and IGF-receptors on a colon carcinoma cell line. STUDY DESIGN: Insulin-like growth factor-II mRNAs were examined by Northern analysis; conditioned media from colon carcinoma cells were concentrated, chromatographed, and examined by a specific IGF-II radioreceptor assay. Insulin-like growth factor receptors were examined by radioligand binding assays. The mitogenic role of IGF-II was determined by a 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide assay. RESULTS: Multiple sizes of IGF-II mRNAs were expressed in all colon carcinoma cell lines tested (six human cell lines: HCT116, COLO 205, COLO 320 DM, LoVo, DLD-1, and HT29, and one mouse cell line: MC-26). In the conditioned media of COLO 205 and HCT116 cells, 7.5 kilodaltons IGF-II and high molecular form (IGF-II and IGF binding protein complex) were detected. Both Type I and Type II IGF receptors were present on COLO 205 cells whose growth was stimulated by IGF-II. Addition of anti-IGF-I receptor and anti-IGF-II antibody in the cell culture significantly depressed growth of the COLO 205 cell line in the presence or absence of exogenous IGF-II. CONCLUSIONS: Insulin-like growth factor-II mRNAs are expressed in human and mouse colon carcinoma cell lines, which may induce production of a significant amount of biologically active IGF-II protein. The IGF-II secreted by COLO 205 cells may stimulate cell growth in an autocrine fashion through the Type I IGF receptors.