Decreased expression of insulin-like growth factor binding protein 6 is associated with gastric adenocarcinoma prognosis

Expression characteristics and their functional role of IGFBP gene family in pan-cancer

BACKGROUND

Insulin-like growth factor binding proteins (IGFBPs) are critical regulators of the biological activities of insulin-like growth factors. The IGFBP family plays diverse roles in different types of cancer, which we still lack comprehensive and pleiotropic understandings so far.

METHODS

Multi-source and multi-dimensional data, extracted from The Cancer Genome Atlas (TCGA), Oncomine, Cancer Cell Line Encyclopedia (CCLE), and the Human Protein Atlas (HPA) was used for bioinformatics analysis by R language. Immunohistochemistry and qRT-PCR were performed to validate the results of the database analysis results. Bibliometrics and literature review were used for summarizing the research progress of IGFBPs in the field of tumor.

RESULTS

The members of IGFBP gene family are differentially expressed in various cancer types. IGFBPs expression can affect prognosis of different cancers. The expression of IGFBPs expression is associated with multiple signal transduction pathways. The expression of IGFBPs is significantly correlated with tumor mutational burden, microsatellite instability, tumor stemness and tumor immune microenvironment. The qRT-PCR experiments verified the lower expression of IGFBP2 and IGFBP6 in gastric cancer and the lower expression of IGFBP6 in colorectal cancer. Immunohistochemistry validated a marked downregulation of IGFBP2 protein in gastric cancer tissues. The keywords co-occurrence analysis of IGFBP related publications in cancer showed relative research have been more concentrating on the potential of IGFBPs as tumor diagnostic and prognostic markers and developing cancer therapies.

CONCLUSIONS

These findings provide frontier trend of IGFBPs related research and new clues for identifying novel therapeutic targets for various cancers.

OASL knockdown inhibits the progression of stomach adenocarcinoma by regulating the mTORC1 signaling pathway

The present study investigated the effects of 2'-5' oligoadenylate synthetase-like (OASL) on the biological functions of stomach adenocarcinoma (STAD) cells and tumor formation in nude mice. The differential expression levels of OASL in the different cancer types from TCGA dataset were analyzed using gene expression profiling interactive analysis. Overall survival and the receiver operating characteristic were analyzed using the KM plotter and R, respectively. Furthermore, OASL expression and its effects on the biological functions of STAD cells were detected. The possible upstream transcription factors of OASL were predicted using JASPAR. The downstream signaling pathways of OASL were analyzed using GSEA. Tumor formation experiments were performed to evaluate the effect of OASL on tumor formation in nude mice. The results showed that OASL was highly expressed in STAD tissues and cell lines. OASL knockdown markedly inhibited cell viability, proliferation, migration, and invasion and accelerated STAD cell apoptosis. Conversely, OASL overexpression had the opposite effect on STAD cells. JASPAR analysis revealed that STAT1 is an upstream transcription factor of OASL. Furthermore, GSEA showed that OASL activated the mTORC1 signaling pathway in STAD. The protein expression levels of p-mTOR and p-RPS6KB1 were suppressed by OASL knockdown and promoted by OASL overexpression. The mTOR inhibitor, rapamycin, markedly reversed the effect of OASL overexpression on STAD cells. Additionally, OASL promoted tumor formation and increased tumor weight and volume in vivo. In conclusion, OASL knockdown suppressed the proliferation, migration, invasion, and tumor formation of STAD cells by inhibiting the mTOR signaling pathway.

The Prognostic Values of the Insulin-Like Growth Factor Binding Protein Family in Ovarian Cancer

Purpose

To assess the expression of insulin-like growth factor binding protein (IGFBP) family and its prognostic impact in ovarian cancer (OC) patients.

Materials and Methods

The mRNA expression and protein expression of individual IGFBPs in healthy ovarian samples and OC tissues were explored through Oncomine, Gene Expression Profiling Interactive Analysis, and Human Protein Atlas database. Additionally, the prognostic values of the six IGFBP members in patients with OC were evaluated by Kaplan-Meier plotter.

Results

IGFBP2 and IGFBP4 mRNA expression were remarkably upregulated in patients with OC. To be specific, the mRNA expression of IGFBP2 was upregulated in patients with serous ovarian cancer (SOC), while IGFBP1/3/4/5/6 mRNA levels were downregulated. In addition, the IGFBP4 protein expression was upregulated in SOC, and the IGFBP6 protein expression was upregulated in both of SOC and endometrioid ovarian cancer (EOC) tissues. High IGFBP1 mRNA levels showed favorable overall survival (OS) and progression-free survival (PFS) in all OC. Meanwhile, increased IGFBP5/6 mRNA levels revealed worsen OS and PFS in all OC patients. IGFBP4/6 mRNA levels predicted unfavorable OS and PFS only in SOC patients. Moreover, the aberrant mRNA expression of IGFBP1/2/4/5/6 was correlated with significantly prognosis in patients receiving different chemotherapeutic regimens.

Conclusion

This study indicates that the IGFBP family reveals distinct prognosis in patients with OC. IGFBP1/2/4/5/6 are useful prognostic predictors for chemotherapeutic effect in OC patients, and IGFBP2/4 are potential tumor markers for the diagnosis of OC.

Decreased expression of IGFBP6 correlates with poor survival in colorectal cancer patients

BACKGROUND

The insulin-like growth factor binding protein 6 (IGFBP6), as a specific inhibitor of IGF-Ⅱ, is a candidate human anti-oncogene in multiple tumors. However, the expression of IGFBP6 in colorectal cancer (CRC) and prognostic significance are unclear.

METHODS

In this study, we examined colorectal cancer tissues and adjacent normal tissues to determine the expression levels of IGFBP6 mRNA and protein by quantitative reverse-transcription polymerase chain reaction and tissue microarray immunohistochemistry analysis respectively. Moreover, we explored the effects of IGFBP6 on cell growth, migration and invasion by Cell Counting Kit-8(CCK8), colony formation and transwell migration assays. We also investigated whether IGFBP6 expression in tumor tissue correlated with various clinical parameters, including overall survival by univariate and multivariate analyses RESULTS: Both IGFBP6 mRNA and protein levels were significantly lower in colorectal cancer tissues than in adjacent normal colon. Downregulating IGFBP6 using RNAi increased CRC cell proliferation, migration and invasion. Low IGFBP6 expression correlated with poor overall survival in both univariate and multivariate analyses.

CONCLUSION

Our data suggest that IGFBP6 may act as a tumor suppressor gene in the development of CRC, and that low IGFBP6 expression could be used as an independent prognostic biomarker in CRC.

IGF-binding proteins

Insulin-like growth factor-binding proteins (IGFBPs) 1-6 bind IGFs but not insulin with high affinity. They were initially identified as serum carriers and passive inhibitors of IGF actions. However, subsequent studies showed that, although IGFBPs inhibit IGF actions in many circumstances, they may also potentiate these actions. IGFBPs are widely expressed in most tissues, and they are flexible endocrine and autocrine/paracrine regulators of IGF activity, which is essential for this important physiological system. More recently, individual IGFBPs have been shown to have IGF-independent actions. Mechanisms underlying these actions include (i) interaction with non-IGF proteins in compartments including the extracellular space and matrix, the cell surface and intracellular space, (ii) interaction with and modulation of other growth factor pathways including EGF, TGF-β and VEGF, and (iii) direct or indirect transcriptional effects following nuclear entry of IGFBPs. Through these IGF-dependent and IGF-independent actions, IGFBPs modulate essential cellular processes including proliferation, survival, migration, senescence, autophagy and angiogenesis. They have been implicated in a range of disorders including malignant, metabolic, neurological and immune diseases. A more complete understanding of their cellular roles may lead to the development of novel IGFBP-based therapeutic opportunities.

Role of IGFBP6 Protein in the Regulation of Epithelial-Mesenchymal Transition Genes

Protein IGFBP6 plays an important role in the pathogenesis of many malignant tumors, including breast cancer. The relationship between IGFBP6 protein and the expression of genes associated with the epithelial-mesenchymal transition is studied. Gene IGFBP6 knockdown does not trigger the epithelial-mesenchymal transition in MDA-MB-231 cells, but modifies significantly the expression of many genes involved in this process. A decrease of IGFBP6 expression can involve a decrease in the expression of N-cadherin and transcription factor Slug.

Insulin-Like Growth Factor-Binding Proteins of Teleost Fishes

The insulin-like growth factor (Igf) binding protein (Igfbp) family has a broad range of physiological functions and a fascinating evolutionary history. This review focuses on the Igfbps of teleost fishes, where genome duplication events have diversified gene repertoire, function, and physiological regulation-with six core Igfbps expanded into a family of over twenty genes in some lineages. In addition to briefly summarizing the current state of knowledge on teleost Igfbp evolution, function, and expression-level regulation, we highlight gaps in our understanding and promising areas for future work.