IGF2 knockdown in two colorectal cancer cell lines decreases survival, adhesion and modulates survival-associated genes

Insulin-like growth factor 2 hypermethylation in peripheral blood leukocytes and colorectal cancer risk and prognosis: a propensity score analysis

Background

To comprehensively assess and validate the associations between insulin-like growth factor 2 (IGF2) gene methylation in peripheral blood leukocytes (PBLs) and colorectal cancer (CRC) risk and prognosis.

Methods

The association between IGF2 methylation in PBLs and CRC risk was initially evaluated in a case-control study and then validated in a nested case-control study and a twins' case-control study, respectively. Meanwhile, an initial CRC patient cohort was used to assess the effect of IGF2 methylation on CRC prognosis and then the finding was validated in the EPIC-Italy CRC cohort and TCGA datasets. A propensity score (PS) analysis was performed to control for confounders, and extensive sensitivity analyses were performed to assess the robustness of our findings.

Results

PBL IGF2 hypermethylation was associated with an increased risk of CRC in the initial study (OR_PS-adjusted, 2.57, 95% CI: 1.65 to 4.03, P<0.0001), and this association was validated using two independent external datasets (OR_PS-adjusted, 2.21, 95% CI: 1.28 to 3.81, P=0.0042 and OR_PS-adjusted, 10.65, 95% CI: 1.26 to 89.71, P=0.0295, respectively). CRC patients with IGF2 hypermethylation in PBLs had significantly improved overall survival compared to those patients with IGF2 hypomethylation (HR_PS-adjusted, 0.47, 95% CI: 0.29 to 0.76, P=0.0019). The prognostic signature was also observed in the EPIC-Italy CRC cohort, although the HR did not reach statistical significance (HR_PS-adjusted, 0.69, 95% CI: 0.37 to 1.27, P=0.2359).

Conclusions

IGF2 hypermethylation may serve as a potential blood-based predictive biomarker for the identification of individuals at high risk of developing CRC and for CRC prognosis.

Long Non-Coding RNAs in Pancreatic Cancer: Biologic Functions, Mechanisms, and Clinical Significance

Despite tremendous efforts devoted to research in pancreatic cancer (PC), the mechanism underlying the tumorigenesis and progression of PC is still not completely clear. Additionally, ideal biomarkers and satisfactory therapeutic strategies for clinical application in PC are still lacking. Accumulating evidence suggests that long non-coding RNAs (lncRNAs) might participate in the pathogenesis of diverse cancers, including PC. The abnormal expression of lncRNAs in PC is considered a vital factor during tumorigenesis that affects tumor cell proliferation, migration, invasion, apoptosis, angiogenesis, and drug resistance. With this review of relevant articles published in recent years, we aimed to summarize the biogenesis mechanism, classifications, and modes of action of lncRNAs and to review the functions and mechanisms of lncRNAs in PC. Additionally, the clinical significance of lncRNAs in PC was discussed. Finally, we pointed out the questions remaining from recent studies and anticipated that further investigations would address these gaps in knowledge in this field.

Critical role of SOX2-IGF2 signaling in aggressiveness of bladder cancer

Signaling elicited by the stem cell factors SOX2, OCT4, KLF4, and MYC not only mediates reprogramming of differentiated cells to pluripotency but has also been correlated with tumor malignancy. In this study, we found SOX2 expression signifies poor recurrence-free survival and correlates with advanced pathological grade in bladder cancer. SOX2 silencing attenuated bladder cancer cell growth, while its expression promoted cancer cell survival and proliferation. Under low-serum stress, SOX2 expression promoted AKT phosphorylation and bladder cancer cells’ spheroid-forming capability. Furthermore, pharmacological inhibition of AKT phosphorylation, using MK2206, inhibited the SOX2-mediated spheroid formation of bladder cancer cells. Gene expression profiling showed that SOX2 expression, in turn, induced IGF2 expression, while SOX2 silencing inhibited IGF2 expression. Moreover, knocking down IGF2 and IGF1R diminished bladder cancer cell growth. Lastly, pharmacological inhibition of IGF1R, using linsitinib, also inhibited the SOX2-mediated spheroid formation of bladder cancer cells under low-serum stress. Our findings indicate the SOX2–IGF2 signaling affects the aggressiveness of bladder cancer cell growth. This signaling could be a promising biomarker and therapeutic target for bladder cancer intervention.

Insulin-like growth factor (IGF)-II- mediated fibrosis in pathogenic lung conditions

Type 2 insulin-like growth factor (IGF-II) levels are increased in fibrosing lung diseases such as idiopathic pulmonary fibrosis (IPF) and scleroderma/systemic sclerosis-associated pulmonary fibrosis (SSc). Our goal was to investigate the contribution of IGF receptors to IGF-II-mediated fibrosis in these diseases and identify other potential mechanisms key to the fibrotic process. Cognate receptor gene and protein expression were analyzed with qRT-PCR and immunoblot in primary fibroblasts derived from lung tissues of normal donors (NL) and patients with IPF or SSc. Compared to NL, steady-state receptor gene expression was decreased in SSc but not in IPF. IGF-II stimulation differentially decreased receptor mRNA and protein levels in NL, IPF, and SSc fibroblasts. Neutralizing antibody, siRNA, and receptor inhibition targeting endogenous IGF-II and its primary receptors, type 1 IGF receptor (IGF1R), IGF2R, and insulin receptor (IR) resulted in loss of the IGF-II response. IGF-II tipped the TIMP:MMP balance, promoting a fibrotic environment both intracellularly and extracellularly. Differentiation of fibroblasts into myofibroblasts by IGF-II was blocked with a TGFβ1 receptor inhibitor. IGF-II also increased TGFβ2 and TGFβ3 expression, with subsequent activation of canonical SMAD2/3 signaling. Therefore, IGF-II promoted fibrosis through IGF1R, IR, and IGF1R/IR, differentiated fibroblasts into myofibroblasts, decreased protease production and extracellular matrix degradation, and stimulated expression of two TGFβ isoforms, suggesting that IGF-II exerts pro-fibrotic effects via multiple mechanisms.

Insulin-Like Growth Factor 2 (IGF2) Signaling in Colorectal Cancer-From Basic Research to Potential Clinical Applications

Colorectal cancer (CRC) is one of the most common cancers in men and women worldwide as well as is the leading cause of death in the western world. Almost a third of the patients has or will develop liver metastases. While genetic as well as epigenetic mechanisms are important in CRC pathogenesis, the basis of the most cases of cancer is unknown. High spatial and inter-patient variability of the molecular alterations qualifies this cancer in the group of highly heterogeneous tumors, which makes it harder to elucidate the mechanisms underlying CRC progression. Determination of highly sensitive and specific early diagnosis markers and understanding the cellular and molecular mechanism(s) of cancer progression are still a challenge of the current era in oncology of solid tumors. One of the accepted risk factors for CRC development is overexpression of insulin-like growth factor 2 (IGF2), a 7.5-kDa peptide produced by liver and many other tissues. IGF2 is the first gene discovered to be parentally imprinted. Loss of imprinting (LOI) or aberrant imprinting of IGF2 could lead to IGF2 overexpression, increased cell proliferation, and CRC development. IGF2 as a mitogen is associated with increased risk of developing colorectal neoplasia. Higher serum IGF2 concentration as well as its tissue overexpression in CRC compared to control are associated with metastasis. IGF2 protein was one of the three candidates for a selective marker of CRC progression and staging. Recent research indicates dysregulation of different micro- and long non-coding RNAs (miRNAs and lncRNAs, respectively) embedded within the IGF2 gene in CRC carcinogenesis, with some of them indicated as potential diagnostic and prognostic CRC biomarkers. This review systematises the knowledge on the role of genetic and epigenetic instabilities of IGF2 gene, free (active form of IGF2) and IGF-binding protein (IGFBP) bound (inactive form), paracrine/autocrine secretion of IGF2, as well as mechanisms of inducing dysplasia in vitro and tumorigenicity in vivo. We have tried to answer which molecular changes of the IGF2 gene and its regulatory mechanisms have the most significance in initiation, progression (including liver metastasis), prognosis, and potential anti-IGF2 therapy in CRC patients.

lncINS-IGF2 Promotes Cell Proliferation and Migration by Promoting G1/S Transition in Lung Cancer

Long noncoding RNAs are capable of regulating gene expression at multiple levels. These RNA molecules are also involved in a variety of physiological and pathological processes. Emerging data demonstrate that a series of differentially expressed long noncoding RNAs are implicated in tumorigenesis. In the present study, we used microarray analysis to identify long noncoding RNAs that are dysregulated in non-small-cell lung cancer when compared to normal lung tissues. Accordingly, we performed quantitative real-time polymerase chain reaction to analyze the levels of long noncoding RNA and the cis target gene. We further found the oncogene property of long noncoding RNA that long noncoding RNA downexpression inhibits non-small-cell lung cancer cells proliferation and migration based on 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide and colony formation assays and wound healing as well as transwell assays. The influence of long noncoding RNA on cell cycle of non-small-cell lung cancer cells is also analyzed by flow cytometry. Among the dysregulated long noncoding RNAs, we identified INS-IGF2 readthrough, transcript variant 1, noncoding RNA (NR_003512.3) is upregulated in non-small-cell lung cancer tissues, the cis gene of which is insulin-like growth factor 2 gene hinted by bioinformatics analysis. We also observed that downregulation of INS-IGF2 readthrough, transcript variant 1, noncoding RNA reduces insulin-like growth factor 2 messenger RNA expression. Furthermore, INS-IGF2 readthrough, transcript variant 1, noncoding RNA downregulation suppresses non-small-cell lung cancer cell proliferation and migration. This downregulation results in a concomitant inhibition of the G1/S transition in non-small-cell lung cancer cells. Our findings suggest that INS-IGF2 readthrough, transcript variant 1, noncoding RNA may be an oncogene involved in the development of lung cancer. Therefore, we speculate that INS-IGF2 readthrough, transcript variant 1, noncoding RNA represents a potential therapeutic target for lung cancer.

Epigenetic inhibition of miR-663b by long non-coding RNA HOTAIR promotes pancreatic cancer cell proliferation via up-regulation of insulin-like growth factor 2

Pancreatic cancer is one of the most deadly cancers with a poor prognosis. Although microRNAs are involving in the carcinogenesis and development of pancreatic cancer, little information is known regarding the role of miR-663b in pancreatic cancer. In this study, the expression of miR-663b in pancreatic cancer cells was down-regulated by hypermethylation in its putative promoter region, and overexpression of miR-663b repressed cell proliferation, invasion and migration, and induced apoptosis in pancreatic cancer cells. Bioinformatics analysis, luciferase report assay and rescue experiments showed that insulin-like growth factor 2 (IGF2) was a direct target of miR-663b. Results from clinical samples showed that the expression level of miR-663b correlated with the pathological grading, and the expression of miR-663b was down-regulated and was inversely correlated with IGF2 expression level in pancreatic cancer tissues. More importantly, the long non-coding RNA, HOX transcript antisense RNA (HOTAIR), was up-regulated in both pancreatic cancer cells and tissues, and HOTAIR suppressed the expression of miR-663b in pancreatic cancer by histone modification on H3K4me3 and H3K27me3 on miR-663b promoter. Further in vivo studies demonstrated that the stable overexpression of miR-663b or knock-down of HOTAIR inhibited tumor growth and was associated with IGF2 expression. In summary, our studies demonstrated that miR-663b is epigenetically repressed by HOTAIR and exerts its tumor-suppressive function via targeting IGF2 in pancreatic cancer.

Dissection of Myogenic Differentiation Signatures in Chickens by RNA-Seq Analysis

A series of elaborately regulated and orchestrated changes in gene expression profiles leads to muscle growth and development. In this study, RNA sequencing was used to profile embryonic chicken myoblasts and fused myotube transcriptomes, long non-coding RNAs (lncRNAs), and messenger RNAs (mRNAs) at four stages of myoblast differentiation. Of a total of 2484 lncRNA transcripts, 2288 were long intergenic non-coding RNAs (lincRNAs) and 198 were antisense lncRNAs. Additionally, 1530 lncRNAs were neighboring 2041 protein-coding genes (<10 kb upstream and downstream) and functionally enriched in several pathways related to skeletal muscle development that have been extensively studied, indicating that these genes may be in cis-regulatory relationships. In addition, Pearson’s correlation coefficients demonstrated that 990 lncRNAs and 7436 mRNAs were possibly in trans-regulatory relationships. These co-expressed mRNAs were enriched in various developmentally-related biological processes, such as myocyte proliferation and differentiation, myoblast differentiation, and myoblast fusion. The number of transcripts (906 lncRNAs and 4422 mRNAs) differentially expressed across various stages declined with the progression of differentiation. Then, 4422 differentially expressed genes were assigned to four clusters according to K-means analysis. Genes in the K1 cluster likely play important roles in myoblast proliferation and those in the K4 cluster were likely associated with the initiation of myoblast differentiation, while genes in the K2 and K3 clusters were likely related to myoblast fusion. This study provides a catalog of chicken lncRNAs and mRNAs for further experimental investigations and facilitates a better understanding of skeletal muscle development.