The IGF-1 receptor in cancer biology

TRPV1 inhibition suppresses non-small cell lung cancer progression by inhibiting tumour growth and enhancing the immune response

PURPOSE

TRPV1 is a nonselective Ca2+ channel protein that is widely expressed and plays an important role during the occurrence and development of many cancers. Activation of TRPV1 channels can affect tumour progression by regulating proliferation, apoptosis and migration. Some studies have also shown that activating TRPV1 can affect tumour progression by modulating tumour immunity. However, the effects of TRPV1 on the development of non-small cell lung cancer (NSCLC) have not been explored clearly.

METHOD

The Cancer Genome Atlas (TCGA) database and spatial transcriptomics datasets from 10 × Genomics were used to analyze TRPV1 expression in various tumour tissues. Cell proliferation and apoptosis were examined by cell counting kit 8 (CCK8), colony formation, and flow cytometry. Immunohistochemistry, qPCR, and western blotting were used to determine the mRNA and protein expression levels of TRPV1 and other related molecules. Tumour xenografts in BALB/C and C57BL/6J mice were used to determine the effects of TRPV1 on NSCLC development in vivo. Neurotransmitter content was examined by LC-MS/MS, ELISA and Immunohistochemistry. Immune cell infiltration was assessed by flow cytometry.

RESULTS

In this study, we found that TRPV1 expression was significantly upregulated in NSCLC and that patients with high TRPV1 expression had a poor prognosis. TRPV1 knockdown can significantly inhibit NSCLC proliferation and induce cell apoptosis through Ca2+-IGF1R signaling. In addition, TRPV1 knockdown resulted in increased infiltration of CD4+ T cells, CD8+ T cells, GZMB+CD8+ T cells and DCs and decreased infiltration of immunosuppressive MDSCs in NSCLC. In addition, TRPV1 knockout effectively decreased the expression of M2 macrophage markers CD163 and increased the expression of M1-associated, costimulatory markers CD86. Knockdown or knockout of TRPV1 significantly inhibit tumour growth and promoted an antitumour immune response through supressing γ-aminobutyric acid (GABA) secretion in NSCLC.

CONCLUSION

Our study suggests that TRPV1 acts as a tumour promoter in NSCLC, mediating pro-proliferative and anti-apoptotic effects on NSCLC through IGF1R signaling and regulating GABA release to affect the tumour immune response.

Analyses of lncRNA and mRNA profiles in recurrent atrial fibrillation after catheter ablation

BACKGROUND

Atrial fibrillation (AF) is the most common cardiac arrhythmia worldwide. Catheter ablation has become a crucial treatment for AF. However, there is a possibility of atrial fibrillation recurrence after catheter ablation. Our study sought to elucidate the role of lncRNA‒mRNA regulatory networks in late AF recurrence after catheter ablation.

METHODS

We conducted RNA sequencing to profile the transcriptomes of 5 samples from the presence of recurrence after AF ablation (P-RAF) and 5 samples from the absence of recurrence after AF ablation (A-RAF). Differentially expressed genes (DEGs) and long noncoding RNAs (DE-lncRNAs) were analyzed using the DESeq2 R package. The functional correlations of the DEGs were assessed through Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. A protein‒protein interaction (PPI) network was constructed using STRING and Cytoscape. We also established a lncRNA‒mRNA regulatory network between DE-lncRNAs and DEGs using BEDTools v2.1.2 software and the Pearson correlation coefficient method. To validate the high-throughput sequencing results of the hub genes, we conducted quantitative real-time polymerase chain reaction (qRT‒PCR) experiments.

RESULTS

A total of 28,528 mRNAs and 42,333 lncRNAs were detected. A total of 96 DEGs and 203 DE-lncRNAs were identified between the two groups. GO analysis revealed that the DEGs were enriched in the biological processes (BPs) of "regulation of immune response" and "regulation of immune system process", the cellular components (CCs) of "extracellular matrix" and "cell‒cell junction", and the molecular functions (MFs) of "signaling adaptor activity" and "protein-macromolecule adaptor activity". According to the KEGG analysis, the DEGs were associated with the "PI3K-Akt signaling pathway" and "MAPK signaling pathway." Nine hub genes (MMP9, IGF2, FGFR1, HSPG2, GZMB, PEG10, GNLY, COL6A1, and KCNE3) were identified through the PPI network. lncRNA-TMEM51-AS1-201 was identified as a core regulator in the lncRNA‒mRNA regulatory network, suggesting its potential impact on the recurrence of AF after catheter ablation through the regulation of COL6A1, FGFR1, HSPG2, and IGF2.

CONCLUSIONS

The recurrence of atrial fibrillation after catheter ablation may be associated with immune responses and fibrosis, with the extracellular matrix playing a crucial role. TMEM51-AS1-201 has been identified as a potential key target for AF recurrence after catheter ablation.

Anthriscus sylvestris-Noxious Weed or Sustainable Source of Bioactive Lignans?

Anthriscus sylvestris (L.) Hoffm. (Apiaceae), commonly known as wild chervil, has gained scientific interest owing to its diverse phytochemical profile and potential therapeutic applications. The plant, despite being categorized as a noxious weed, is traditionally used in treating various conditions like headaches, dressing wounds, and as a tonic, antitussive, antipyretic, analgesic, and diuretic. Its pharmacological importance stems from containing diverse bioactive lignans, especially aryltetralins and dibenzylbutyrolactones. One of the main compounds of A. sylvestris, deoxypodophyllotoxin, among its wide-ranging effects, including antitumor, antiproliferative, antiplatelet aggregation, antiviral, anti-inflammatory, and insecticidal properties, serves as a pivotal precursor to epipodophyllotoxin, crucial in the semisynthesis of cytostatic agents like etoposide and teniposide. The main starting compound for these anticancer medicines was podophyllotoxin, intensively isolated from Sinopodophyllum hexandrum, now listed as an endangered species due to overexploitation. Since new species are being investigated as potential sources, A. sylvestris emerges as a highly promising candidate owing to its abundant lignan content. This review summarizes the current knowledge on A. sylvestris, investigating its biological and morphological characteristics, and pharmacological properties. Emphasizing the biological activities and structure-activity relationship, this review underscores its therapeutic potential, thus encouraging further exploration and utilization of this valuable plant resource.

Keratinocyte-derived circulating microRNAs in extracellular vesicles: a novel biomarker of psoriasis severity and potential therapeutic target

BACKGROUND

Psoriasis is a chronic inflammatory disorder characterized by pathogenic hyperproliferation of keratinocytes and immune dysregulation. Currently, objective evaluation tools reflecting the severity of psoriasis are insufficient. MicroRNAs in extracellular vesicles (EV miRNAs) have been shown to be potential biomarkers for various inflammatory diseases. Our objective was to investigate the possibility of plasma-derived EV miRNAs as a marker for the psoriasis disease severity.

METHODS

EVs were extracted from the plasma of 63 patients with psoriasis and 12 with Behçet's disease. We performed next-generation sequencing of the plasma-derived EV miRNAs from the psoriasis patients. Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to validate the level of EV miRNA expression. In situ hybridization was used to discern the anatomical location of miRNAs. qRT-PCR, western blotting, and cell counting kits (CCKs) were used to investigate IGF-1 signaling in cells transfected with miRNA mimics.

RESULTS

We identified 19 differentially expressed EV miRNAs and validated the top three up-and down-regulated EV miRNAs. Among these, miR-625-3p was significantly increased in patients with severe psoriasis in both plasma and skin and most accurately distinguished moderate-to-severe psoriasis from mild-to-moderate psoriasis. It was produced and secreted by keratinocytes upon stimulation. We also observed a significant intensification of IGF-1 signalling and increased cell numbers in the miR-625-3p mimic transfected cells.

CONCLUSIONS

We propose keratinocyte-derived EV miR-625-3p as a novel and reliable biomarker for estimating the severity of psoriasis. This biomarker could objectively evaluate the severity of psoriasis in the clinical setting and might serve as a potential therapeutic target. Trial registration None.

Role of Insulin-like Growth Factor-1 Receptor in Tobacco Smoking-Associated Lung Cancer Development

Cancer remains a significant global health concern, with lung cancer consistently leading as one of the most common malignancies. Genetic aberrations involving receptor tyrosine kinases (RTKs) are known to be associated with cancer initiation and development, but RTK involvement in smoking-associated lung cancer cases is not well understood. The Insulin-like Growth Factor 1 Receptor (IGF-1R) is a receptor that plays a critical role in lung cancer development. Its signaling pathway affects the growth and survival of cancer cells, and high expression is linked to poor prognosis and resistance to treatment. Several reports have shown that by activating IGF-1R, tobacco smoke-related carcinogens promote lung cancer and chemotherapy resistance. However, the relationship between IGF-1R and cancer is complex and can vary depending on the type of cancer. Ongoing investigations are focused on developing therapeutic strategies to target IGF-1R and overcome chemotherapy resistance. Overall, this review explores the intricate connections between tobacco smoke-specific carcinogens and the IGF-1R pathway in lung carcinogenesis. This review further highlights the challenges in using IGF-1R inhibitors as targeted therapy for lung cancer due to structural similarities with insulin receptors. Overcoming these obstacles may require a comprehensive approach combining IGF-1R inhibition with other selective agents for successful cancer treatment.

A revisiting of "the hallmarks of aging" in domestic dogs: current status of the literature

A progressive decline in biological function and fitness is, generally, how aging is defined. However, in 2013, a description on the "hallmarks of aging" in mammals was published, and within it, it described biological processes that are known to alter the aging phenotype. These include genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, altered intercellular communication (inflammation), and changes within the microbiome. This mini-review provides a detailed account of the progress on each of these hallmarks of aging in the domestic dog within the last 5 years. Additionally, when there are gaps in the literature between other mammalian species and dogs, I highlight the aging biomarkers that may be missing for dogs as aging models. I also argue for the importance of dog aging studies to include several breeds of dogs at differing ages and for age corrections for breeds with differing mean lifespans throughout.

Combination of the biomarkers for aging and cancer? - Challenges and current status

The proportion of patients diagnosed with cancer has been shown to rise with the increasing aging global population. Advanced age is a major risk factor for morbidity and mortality in older adults. As individuals experience varying health statuses, particularly with age, it poses a challenge for medical professionals in the cancer field to obtain standardized treatment outcomes. Hence, relying solely on chronological age and disease-related parameters is inadequate for clinical decision-making for elderly patients. With functional, multimorbidity-related, and psychosocial changes that occur with aging, oncologic diseases may develop and be treated differently from younger patients, leading to unique challenges in treatment efficacy and tolerance. To overcome this challenge, personalized therapy using biomarkers has emerged as a promising solution. Various categories of biomarkers, including inflammatory, hematological, metabolic, endocrine, and DNA modification-related indicators, may display features related to both cancer and aging, aiding in the development of innovative therapeutic approaches for patients with cancer in old age. Furthermore, physical functional measurements as non-molecular phenotypic biomarkers are being investigated for their potential complementary role in structured multidomain strategies to combat age-related diseases such as cancer. This review provides insight into the current developments, recent discoveries, and significant challenges in cancer and aging biomarkers, with a specific focus on their application in advanced age.

Targeted immunotherapy for glioblastoma involving whole tumor-derived autologous cells in the upfront setting after craniotomy

PURPOSE

To date, immunotherapeutic approaches in glioblastoma (GBM) have had limited clinical efficacy as compared to other solid tumors. Here we explore autologous cell treatments that have the potential to circumvent treatment resistance to immunotherapy for GBM.

METHODS

We performed literature review and assessed clinical outcomes in phase 1 safety trials as well as phase 2 and 3 autologously-derived vaccines for the treatment of newly-diagnosed GBM. In one recent review of over 3,000 neuro-oncology phase 2 and phase 3 clinical trials, most trials were nonblinded (92%), single group (65%), nonrandomized (51%) and almost half were GBM trials. Only 10% involved a biologic and only 2.2% involved a double-blind randomized trial design.

RESULTS

With this comparative literature review we conclude that our autologous cell product is uniquely antigen-inclusive and antigen-agnostic with a promising safety profile as well as unexpected clinical efficacy in our published phase 1b trial. We have since designed a rigorous double-blinded add-on placebo-controlled trial involving our implantable biologic drug device. We conclude that IGV-001 provides a novel immunotherapy platform for historically intransigent ndGBM in this ongoing phase 2b trial (NCT04485949).

The IGF1 Signaling Pathway: From Basic Concepts to Therapeutic Opportunities

Insulin-like growth factor 1 (IGF1) is a peptide growth factor with important functions in multiple aspects of growth, development and metabolism. The biological actions of IGF1 are mediated by the IGF1 receptor (IGF1R), a cell-surface protein that is evolutionarily related to the insulin receptor (InsR). The effects of IGF1 are moderated by a group of binding proteins (IGFBPs) that bind and transport the ligand in the circulation and extracellular fluids. In mechanistic terms, IGF1R function is linked to the MAPK and PI3K signaling pathways. Furthermore, IGF1R has been shown to migrate to cell nucleus, where it functions as a transcriptional activator. The co-localization of IGF1R and MAPK in the nucleus is of major interest as it suggests novel mechanistic paradigms for the IGF1R-MAPK network. Given its potent anti-apoptotic and pro-survival roles, and in view of its almost universal pattern of expression in most types of cancer, IGF1R has emerged as a promising molecular target in oncology. The present review article provides a concise overview of key scientific developments in the research area of IGF and highlights a number of more recent findings, including its nuclear migration and its interaction with oncogenes and tumor suppressors.

MicroRNAs as the pivotal regulators of cisplatin resistance in osteosarcoma

Osteosarcoma (OS) is an aggressive bone tumor that originates from mesenchymal cells. It is considered as the eighth most frequent childhood cancer that mainly affects the tibia and femur among the teenagers and young adults. OS can be usually diagnosed by a combination of MRI and surgical biopsy. The intra-arterial cisplatin (CDDP) and Adriamycin is one of the methods of choices for the OS treatment. CDDP induces tumor cell death by disturbing the DNA replication. Although, CDDP has a critical role in improving the clinical complication in OS patients, a high ratio of CDDP resistance is observed among these patients. Prolonged CDDP administrations have also serious side effects in normal tissues and organs. Therefore, the molecular mechanisms of CDDP resistance should be clarified to define the novel therapeutic modalities in OS. Multidrug resistance (MDR) can be caused by various cellular and molecular processes such as drug efflux, detoxification, and signaling pathways. MicroRNAs (miRNAs) are the key regulators of CDDP response by the post transcriptional regulation of target genes involved in MDR. In the present review we have discussed all of the miRNAs associated with CDDP response in OS cells. It was observed that the majority of reported miRNAs increased CDDP sensitivity in OS cells through the regulation of signaling pathways, apoptosis, transporters, and autophagy. This review highlights the miRNAs as reliable non-invasive markers for the prediction of CDDP response in OS patients.

To explore the effect of kaempferol on non-small cell lung cancer based on network pharmacology and molecular docking

Non-small cell lung cancer (NSCLC) is a common pathological type of lung cancer, which has a serious impact on human life, health, psychology and life. At present, chemotherapy, targeted therapy and other methods commonly used in clinic are prone to drug resistance and toxic side effects. Natural extracts of traditional Chinese medicine (TCM) have attracted wide attention in cancer treatment because of their small toxic and side effects. Kaempferol is a flavonoid from natural plants, which has been proved to have anticancer properties in many cancers such as lung cancer, but the exact molecular mechanism is still unclear. Therefore, on the basis of in vitro experiments, we used network pharmacology and molecular docking methods to study the potential mechanism of kaempferol in the treatment of non-small cell lung cancer. The target of kaempferol was obtained from the public database (PharmMapper, Swiss target prediction), and the target of non-small cell lung cancer was obtained from the disease database (Genecards and TTD). At the same time, we collected gene chips GSE32863 and GSE75037 in conjunction with GEO database to obtain differential genes. By drawing Venn diagram, we get the intersection target of kaempferol and NSCLC. Through enrichment analysis, PI3K/AKT is identified as the possible key signal pathway. PIK3R1, AKT1, EGFR and IGF1R were selected as key targets by topological analysis and molecular docking, and the four key genes were further verified by analyzing the gene and protein expression of key targets. These findings provide a direction for further research of kaempferol in the treatment of NSCLC.

Metformin: A Review of Potential Mechanism and Therapeutic Utility Beyond Diabetes

Metformin has been designated as one of the most crucial first-line therapeutic agents in the management of type 2 diabetes mellitus. Primarily being an antihyperglycemic agent, metformin also has a plethora of pleiotropic effects on various systems and processes. It acts majorly by activating AMPK (Adenosine Monophosphate-Activated Protein Kinase) in the cells and reducing glucose output from the liver. It also decreases advanced glycation end products and reactive oxygen species production in the endothelium apart from regulating the glucose and lipid metabolism in the cardiomyocytes, hence minimizing the cardiovascular risks. Its anticancer, antiproliferative and apoptosis-inducing effects on malignant cells might prove instrumental in the malignancy of organs like the breast, kidney, brain, ovary, lung, and endometrium. Preclinical studies have also shown some evidence of metformin's neuroprotective role in Parkinson's disease, Alzheimer's disease, multiple sclerosis and Huntington's disease. Metformin exerts its pleiotropic effects through varied pathways of intracellular signalling and exact mechanism in the majority of them remains yet to be clearly defined. This article has extensively reviewed the therapeutic benefits of metformin and the details of its mechanism for a molecule of boon in various conditions like diabetes, prediabetes, obesity, polycystic ovarian disease, metabolic derangement in HIV, various cancers and aging.

A systematic review and meta-analysis for the association of the insulin-like growth factor1 pathway genetic polymorphisms with colorectal cancer susceptibility

Background

The receptors, ligands, and associated proteins of the insulin-like growth factor (IGF) family are involved in cancer development. The IGF1 receptor and its accompanying signaling cascade are a crucial growth-regulatory mechanism that plays an important role in colorectal cancer (CRC) proliferation and differentiation. IRS1 (Insulin receptor substrate-1), a major substrate for the IGF1R, is involved in cell growth and promotes tumorigenesis. There are shreds of evidence from prior research suggesting that IGF system polymorphisms may influence susceptibility to CRC. However, the findings in this area were contradictory. Accordingly, we carried out a systematic literature search to identify all case-control, cross-sectional, and cohort studies on the association between various polymorphisms across four IGF1 pathway genes (IGF1, IGF1R, IRS1, and IRS2) and the risk of CRC.

Methods

We performed a comprehensive search strategy in PubMed, Scopus, and Web of Science databases for articles available until Aug 30, 2022. A total of 26 eligible studies with IGF1/IGF1R, IRS1 and IRS2 polymorphisms; met the inclusion criteria. All case-control studies for IGF1 rs6214C>T, IRS1 rs1801278G>A, and IRS2 rs1805097G>A comprising 22,084 cases and 29,212 controls were included in the current meta-analysis. The pooled odds ratios (ORs) with 95% confidence intervals (CIs) were used to evaluate relationships between the polymorphisms and CRC susceptibility. All statistical analyses were performed using STATA software version 14.0.

Results

The meta-analysis of available data for rs6214C>T, rs1801278G>A, and rs1805097G>A showed a significant association between these polymorphisms and an increased CRC risk in some of the comparisons studied (rs6214C>T, pooled OR for CC = 0.43, 95% CI 0.21- 0.87, P = 0.019; rs1801278G>A, OR for GA = 0.74, 95% CI 0.58-0.94, P = 0.016; rs1805097G>A, OR for GA = 0.83, 95% CI 0.71-0.96, P = 0.013). Nevertheless, the meta-analysis did not include other genetic variations in IGF1, IGF1R, IRS1, and IRS2 due to heterogeneity and limited sample size.

Conclusions

This systematic review and meta-analysis provide evidence that genetic variants in IGF1 rs6214C>T, IRS1 rs1801278G>A, and IRS2 rs1805097G>A are associated with an increased risk of CRC. These findings may contribute to a better understanding of the complex genetic mechanisms involved in CRC development and could inform future research on prevention and treatment strategies for this disease.

Angiogenic signaling pathways and anti-angiogenic therapy for cancer

Angiogenesis, the formation of new blood vessels, is a complex and dynamic process regulated by various pro- and anti-angiogenic molecules, which plays a crucial role in tumor growth, invasion, and metastasis. With the advances in molecular and cellular biology, various biomolecules such as growth factors, chemokines, and adhesion factors involved in tumor angiogenesis has gradually been elucidated. Targeted therapeutic research based on these molecules has driven anti-angiogenic treatment to become a promising strategy in anti-tumor therapy. The most widely used anti-angiogenic agents include monoclonal antibodies and tyrosine kinase inhibitors (TKIs) targeting vascular endothelial growth factor (VEGF) pathway. However, the clinical benefit of this modality has still been limited due to several defects such as adverse events, acquired drug resistance, tumor recurrence, and lack of validated biomarkers, which impel further research on mechanisms of tumor angiogenesis, the development of multiple drugs and the combination therapy to figure out how to improve the therapeutic efficacy. Here, we broadly summarize various signaling pathways in tumor angiogenesis and discuss the development and current challenges of anti-angiogenic therapy. We also propose several new promising approaches to improve anti-angiogenic efficacy and provide a perspective for the development and research of anti-angiogenic therapy.

Autophagy and the Insulin-like Growth Factor (IGF) System in Colonic Cells: Implications for Colorectal Neoplasia

Colorectal cancer (CRC) is one of the most common human malignancies worldwide. Along with apoptosis and inflammation, autophagy is one of three important mechanisms in CRC. The presence of autophagy/mitophagy in most normal mature intestinal epithelial cells has been confirmed, where it has mainly protective functions against reactive oxygen species (ROS)-induced DNA and protein damage. Autophagy regulates cell proliferation, metabolism, differentiation, secretion of mucins and/or anti-microbial peptides. Abnormal autophagy in intestinal epithelial cells leads to dysbiosis, a decline in local immunity and a decrease in cell secretory function. The insulin-like growth factor (IGF) signaling pathway plays an important role in colorectal carcinogenesis. This is evidenced by the biological activities of IGFs (IGF-1 and IGF-2), IGF-1 receptor type 1 (IGF-1R) and IGF-binding proteins (IGF BPs), which have been reported to regulate cell survival, proliferation, differentiation and apoptosis. Defects in autophagy are found in patients with metabolic syndrome (MetS), inflammatory bowel diseases (IBD) and CRC. In neoplastic cells, the IGF system modulates the autophagy process bidirectionally. In the current era of improving CRC therapies, it seems important to investigate the exact mechanisms not only of apoptosis, but also of autophagy in different populations of tumor microenvironment (TME) cells. The role of the IGF system in autophagy in normal as well as transformed colorectal cells still seems poorly understood. Hence, the aim of the review was to summarize the latest knowledge on the role of the IGF system in the molecular mechanisms of autophagy in the normal colon mucosa and in CRC, taking into account the cellular heterogeneity of the colonic and rectal epithelium.

Scaling with body mass and age in glycolytic enzymes of domestic dogs

Animals produce ATP through oxidative phosphorylation using oxygen, but cellular energy can also be obtained through glycolysis when oxygen is not present at sufficient levels. Although most mammals of larger body mass have longer life spans, small dog breeds tend to outlive large breeds. Primary fibroblast cells from larger breeds of dogs have previously been shown to have increased dependency on glycolytic phenotypes across their lifespan. Different levels of activity of the glycolytic enzymes pyruvate kinase (PK), lactate dehydrogenase (LDH), and phosphoenolpyruvate carboxykinase (PEPCK) may provide insight to a mechanism that leads to the different metabolic phenotype observed in different sized breeds as they age. In this study, 1) we measured the activities of PK, LDH, and PEPCK in primary fibroblasts from dogs of different breed sizes and age classes and 2) measured the activities of PK and LDH in plasma from dogs of different breed sizes and age classes. We found that there was no significant relationship between body mass and PK, LDH and PEPCK activity in primary fibroblasts. Further, there were not significant differences with activity in these enzymes for old dogs compared to young dogs. In plasma, we found a negative correlation between PK activity and body mass and no relationship between LDH activity and body mass. There was a negative relationship between LDH activity and age in dogs. Further, while a negative correlational relationship between PK activity and age was only marginal, a best subsets regression model demonstrated a significant marginal effect of age on PK activity. PK and LDH may provide intermediates for other metabolic pathways in small breeds. However, large breed dogs may demonstrate a deficiency in metabolism at the PK level, a cellular metabolic pathway that may potentially aid in tumor progression.

Heat enhances the inhibitory effect of lipopolysaccharide on duck granulosa cell proliferation and steroid biosynthesis in vitro

Lipopolysaccharide (LPS) reduces the reproductive performance of laying ducks, especially during the hot summer months. To study the underlying mechanisms, we investigated the effects of different LPS concentrations and heat on duck granulosa cell (GC) proliferation and steroid biosynthesis in vitro. We investigated GC proliferation, secretion, and activation of the MAPK pathway. The cell cycle results showed that LPS treatment alone did not significantly affect cell proliferation, whereas the mRNA expression levels of IGF2, IGFBP2, and CyclinD1 were downregulated and p27kip1 was significantly upregulated after 2000 ng/mL LPS treatment when compared to untreated cells. In steroid hormone synthesis, although LPS increased the expression of most steroid biosynthesis genes, it inhibited the expression of CYP11A1 at high LPS concentrations. High temperatures enhanced the inhibitory effect of LPS on the expression of proliferation-promoting genes. Heat significantly reduced CYP11A1 and CYP19A1 expression. In addition, the phosphorylation of P38 was significantly upregulated by high temperatures combined with LPS, whereas the phosphorylation of ERK1/2 and JNK was downregulated. The relative protein expression of Bax/BCL-2 was upregulated at high temperatures in combination with LPS. Heat treatment enhanced the inhibitory effects of LPS on the proliferation and hormone biosynthesis of duck GCs in vitro.

Down-regulation of hepatic expression of GHR/STAT5/IGF-1 signaling pathway fosters development and aggressiveness of HCV-related hepatocellular carcinoma: Crosstalk with Snail-1 and type 2 transforming growth factor-beta receptor

Background and aims

So far, few clinical trials are available concerning the role of growth hormone receptor (GHR)/signal transducer and activator of transcription 5 (STAT5)/insulin like growth factor-1 (IGF-1) axis in hepatocarcinogenesis. The aim of this study was to evaluate the hepatic expression of GHR/STAT5/IGF-1 signaling pathway in hepatocellular carcinoma (HCC) patients and to correlate the results with the clinico-pathological features and disease outcome. The interaction between this signaling pathway and some inducers of epithelial-mesenchymal transition (EMT), namely Snail-1 and type 2 transforming growth factor-beta receptor (TGFBR2) was studied too.

Material and methods

A total of 40 patients with HCV-associated HCC were included in this study. They were compared to 40 patients with HCV-related cirrhosis without HCC, and 20 healthy controls. The hepatic expression of GHR, STAT5, IGF-1, Snail-1 and TGFBR2 proteins were assessed by immunohistochemistry.

Results

Compared with cirrhotic patients without HCC and healthy controls, cirrhotic patients with HCC had significantly lower hepatic expression of GHR, STAT5, and IGF-1proteins. They also displayed significantly lower hepatic expression of TGFBR2, but higher expression of Snail-1 versus the non-HCC cirrhotic patients and controls. Serum levels of alpha-fetoprotein (AFP) showed significant negative correlations with hepatic expression of GHR (r = -0.31; p = 0.029) and STAT5 (r = -0.29; p = 0.04). Hepatic expression of Snail-1 also showed negative correlations with GHR, STAT5, and IGF-1 expression (r = -0.55, p = 0.02; r = -0.472, p = 0.035, and r = -0.51, p = 0.009, respectively), whereas, hepatic expression of TGFBR2 was correlated positively with the expression of all these proteins (r = 0.47, p = 0.034; 0.49, p = 0.023, and r = 0.57, p<0.001, respectively). Moreover, we reported that decreased expression of GHR was significantly associated with serum AFP level>100 ng/ml (p = 0.048), increased tumor size (p = 0.02), vascular invasion (p = 0.002), and advanced pathological stage (p = 0.01). Similar significant associations were found between down-regulation of STAT5 expression and AFP level > 100 ng/ml (p = 0.006), vascular invasion (p = 0.009), and advanced tumor stage (p = 0.007). Also, attenuated expression of IGF-1 showed a significant association with vascular invasion (p < 0.001). Intriguingly, we detected that lower expression of GHR, STAT5 and IGF-1 were considered independent predictors for worse outcome in HCC.

Conclusion

Decreased expression of GHR/STAT5/IGF-1 signaling pathway may have a role in development, aggressiveness, and worse outcome of HCV-associated HCC irrespective of the liver functional status. Snail-1 and TGFBR2 as inducers of EMT may be key players. However, large prospective multicenter studies are needed to validate these results.

Roles of N6-methyladenosine (m6A) modifications in gynecologic cancers: mechanisms and therapeutic targeting

Uterine and ovarian cancers are the most common gynecologic cancers. N6−methyladenosine (m6A), an important internal RNA modification in higher eukaryotes, has recently become a hot topic in epigenetic studies. Numerous studies have revealed that the m6A-related regulatory factors regulate the occurrence and metastasis of tumors and drug resistance through various mechanisms. The m6A-related regulatory factors can also be used as therapeutic targets and biomarkers for the early diagnosis of cancers, including gynecologic cancers. This review discusses the role of m6A in gynecologic cancers and summarizes the recent advancements in m6A modification in gynecologic cancers to improve the understanding of the occurrence, diagnosis, treatment, and prognosis of gynecologic cancers.

Loss of E-cadherin Induces IGF1R Activation and Reveals a Targetable Pathway in Invasive Lobular Breast Carcinoma

No special-type breast cancer [NST; commonly known as invasive ductal carcinoma (IDC)] and invasive lobular carcinoma (ILC) are the two major histological subtypes of breast cancer with significant differences in clinicopathological and molecular characteristics. The defining pathognomonic feature of ILC is loss of cellular adhesion protein, E-cadherin (CDH1). We have previously shown that E-cadherin functions as a negative regulator of the IGF1R and propose that E-cadherin loss in ILC sensitizes cells to growth factor signaling that thus alters their sensitivity to growth factor-signaling inhibitors and their downstream activators. To investigate this potential therapeutic vulnerability, we generated CRISPR-mediated CDH1 knockout (CDH1 KO) IDC cell lines (MCF7, T47D, and ZR75.1) to uncover the mechanism by which loss of E-cadherin results in IGF pathway activation. CDH1 KO cells demonstrated enhanced invasion and migration that was further elevated in response to IGF1, serum and collagen I. CDH1 KO cells exhibited increased sensitivity to IGF resulting in elevated downstream signaling. Despite minimal differences in membranous IGF1R levels between wild-type (WT) and CDH1 KO cells, significantly higher ligand-receptor interaction was observed in the CDH1 KO cells, potentially conferring enhanced downstream signaling activation. Critically, increased sensitivity to IGF1R, PI3K, Akt, and MEK inhibitors was observed in CDH1 KO cells and ILC patient-derived organoids.

IMPLICATIONS

Overall, this suggests that these targets require further exploration in ILC treatment and that CDH1 loss may be exploited as a biomarker of response for patient stratification.

GASP1 enhances malignant phenotypes of breast cancer cells and decreases their response to paclitaxel by forming a vicious cycle with IGF1/IGF1R signaling pathway

There is a potential correlation between G-protein-coupled receptor-associated sorting protein 1 (GASP1) and breast tumorigenesis. However, its biological function and underlying molecular mechanism in breast cancer have not been clearly delineated. Here, we demonstrated that GASP1 was highly expressed in breast cancers, and patients harboring altered GASP1 showed a worse prognosis than those with wild-type GASP1. Functional studies showed that GASP1 knockout significantly suppressed malignant properties of breast cancer cells, such as inhibition of cell proliferation, colony formation, migration, invasion and xenograft tumor growth in nude mice as well as induction of G1-phase cell cycle arrest, and vice versa. Mechanistically, GASP1 inhibited proteasomal degradation of insulin-like growth factor 1 receptor (IGF1R) by competitively binding to IGF1R with ubiquitin E3 ligase MDM2, thereby activating its downstream signaling pathways such as NF-κB, PI3K/AKT, and MAPK/ERK pathways given their critical roles in breast tumorigenesis and progression. IGF1, in turn, stimulated GASP1 expression by activating the PI3K/AKT pathway, forming a vicious cycle propelling the malignant progression of breast cancer. Besides, we found that GASP1 knockout obviously improved the response of breast cancer cells to paclitaxel. Collectively, this study demonstrates that GASP1 enhances malignant behaviors of breast cancer cells and decreases their cellular response to paclitaxel by interacting with and stabilizing IGF1R, and suggests that it may serve as a valuable prognostic factor and potential therapeutic target in breast cancer.

Roles of IGFBP-3 in cell migration and growth in an endophytic tongue squamous cell carcinoma cell line

Insulin-like growth factor binding protein-3 (IGFBP-3) is a member of the IGFBP family that has high affinity for IGFs and functions as either an oncogene or tumor suppressor in various types of cancer. We previously found that IGFBP3 mRNA levels are higher in endophytic-type human tongue squamous cell carcinoma (TSCC) that is more invasive and more prone to metastasis than exophytic and superficial types. This finding prompted us to investigate the roles of IGFBP-3 in TSCC using SAS cells, which were originally derived from endophytic-type TSCC. Specifically, we used SAS cells that express a fluorescent ubiquitination-based cell-cycle indicator (Fucci). RNA-sequencing analysis indicated that IGFBP-3 is associated with cell migration and cell growth. In fact, IGFBP-3 knockdown downregulates cell migration and causes cells to arrest in G₁. This migratory potential appears to be cell cycle–independent. IGFBP-3 knockdown also reduced levels of secreted IGFBP-3; however, decreased migratory potential was not rescued by exogenous recombinant human IGFBP-3. Furthermore, ERK activity was downregulated by IGFBP-3 depletion, which suggests that MEK/ERK signaling may be involved in IGFBP-3-mediated cell migration. We therefore conclude that intracellular IGFBP-3 enhances cell migration independently of the cell cycle in TSCC with a higher metastatic potential.

IGF-I and Hyaluronic Acid Mitigate the Negative Effect of Irradiation on Human Skin Keratinocytes

Simple Summary

Patients undergoing radiation therapy for the treatment of various types of cancer often experience side effects such as radiation dermatitis. A gold standard treatment is still lacking. The objective of the present study was to find novel therapeutic strategies for the regeneration and repair of damaged skin areas after irradiation. An in vitro 2D and 3D primary keratinocyte model was used to test the effect of insulin-like growth factor I (IGF-I), keratinocyte growth factor (KGF), platelet lysate (PL), hyaluronic acid (HA), and adipose-derived stem cell (ADSC) conditioned medium on the functional abilities (viability, migration) and the gene expression of irradiated keratinocytes. Hyaluronic acid and IGF-I effectively reduced the irradiation damage of primary keratinocytes by stimulating viability and migration and reducing cell apoptosis and necrosis. These findings indicate that the negative effects of irradiation on keratinocytes located in the patient’s skin can be counterbalanced with HA and IGF-I treatment.

Abstract

Ionizing radiation has become an integral part of modern cancer therapy regimens. Various side effects, such as radiation dermatitis, affect patients in acute and chronic forms and decrease therapy compliance significantly. In this study, primary keratinocytes were irradiated in a 2-dimensional (2D) culture as well as on a 3-dimensional (3D) collagen-elastin matrix with doses of 2 and 5 Gy. The effect of different concentrations of IGF-I, KGF, platelet lysate (PL), high and low molecular weight hyaluronic acid (H-HA, L-HA), and adipose-derived stem cell (ADSC) conditioned medium was analyzed in respect to cell viability (WST-8), wound closure (migration), and the gene expression (quantitative real-time PCR) of 2D cultures. The 3D culture was evaluated by WST-8. A mixture of H-HA and L-HA, as well as IGF-I, could significantly stimulate the keratinocyte viability and migration which were severely reduced by irradiation. The MKI67and IL6 gene expression of irradiated keratinocytes was significantly higher after H-HA/L-HA treatment. The stimulating effects of H-HA/L-HA and IGF-I were able to be confirmed in 3D culture. A positive influence on cell viability, migration, and gene expression was achieved after the treatment with H-L-HA and IGF-I. These results open the possibility of a novel therapeutic method for both the prevention and the treatment of radiation dermatitis.

Targeting the IGF-1R in prostate and colorectal cancer: reasons behind trial failure and future directions

IGF-1Rs enact a significant part in cancer growth and its progress. IGF-1R inhibitors were encouraged in the early trials, but the patients did not benefit due to the unavailability of predictive biomarkers and IGF-1R system complexity. However, the linkage between IGF-1R and cancer was reported three decades ago. This review will shed light on the IGF-1R system, targeting IGF-1R through monoclonal antibodies, reasons behind IGF-1R trial failure and future directions. This study presented that targeting IGF-1R through monoclonal antibodies is still effective in cancer treatment, and there is a need to look for future directions. Cancer patients may benefit from using mAbs that target existing and new cancer targets, evidenced by promising results. It is also essential that the academician, trial experts and pharmaceutical companies play their role in finding a treatment for this deadly disease.

BRCA1: An Endocrine and Metabolic Regulator

The breast and ovarian cancer susceptibility gene (BRCA1) is a tumor suppressor whose mutation has been associated with the development of breast, ovarian and, probably, other malignancies at young ages. The BRCA1 gene product participates in multiple biological pathways including the DNA damage response, transcriptional control, cell growth and apoptosis. Inactivating germline mutations of the BRCA1 gene can be detected in a substantial portion of families with inherited breast and/or ovarian cancer. While the genomic and cancer-related actions of BRCA1 have been extensively investigated, not much information exists regarding the cellular and circulating factors involved in regulation of BRCA1 expression and action. The present review article dissects the emerging role of BRCA1 as an important regulator of various endocrine and metabolic axes. Experimental and clinical evidence links BRCA1 with a number of peptide and steroid hormones. Furthermore, comprehensive analyses identified complex interactions between the insulin/insulin-like growth factor-1 (IGF1) signaling axis and BRCA1. The correlation between metabolic disorders, including diabetes and the metabolic syndrome, and BRCA1 mutations, are discussed in this article.

IGF-1R is a molecular determinant for response to p53 reactivation therapy in conjunctival melanoma

As the p53 tumor suppressor is rarely mutated in conjunctival melanoma (CM), we investigated its activation as a potential therapeutic strategy. Preventing p53/Mdm2 interaction by Nutlin-3, the prototypical Mdm2 antagonist, or via direct siRNA Mdm2 depletion, increased p53 and inhibited viability in CM cell lines. The sensitivity to Nutlin-3 p53 reactivation with concomitant Mdm2 stabilization was higher than that achieved by siRNA, indicative of effects on alternative Mdm2 targets, identified as the cancer-protective IGF-1R. Nutlin-3 treatment increased the association between IGF-1R and β-arrestin1, the adaptor protein that brings Mdm2 to the IGF-1R, initiating receptor degradation in a ligand-dependent manner. Controlled expression of β-arrestin1 augmented inhibitory Nutlin-3 effects on CM survival through enhanced IGF-1R degradation. Yet, the effect of IGF-1R downregulation on cell proliferation is balanced by β-arrestin1-induced p53 inhibition. As mitomycin (MMC) is a well-established adjuvant treatment for CM, and it triggers p53 activation through genotoxic stress, we evaluated how these alternative p53-targeting strategies alter the cancer-relevant bioactivities of CM. In 2D and 3D in vitro models, Nutlin-3 or MMC alone, or in combination, reduces the overall cell tumor growth ~30%, with double treatment inhibition rate only marginally higher than single-drug regimens. However, histopathological evaluation of the 3D models revealed that Nutlin-3 was the most effective, causing necrotic areas inside spheroids and complete loss of nuclear staining for the proliferative marker Ki67. These findings were further validated in vivo; zebrafish xenografts demonstrate that Nutlin-3 alone has higher efficacy in restraining CM tumor cell growth and preventing metastasis. Combined, these results reveal that β-arrestin1 directs Mdm2 toward different substrates, thus balancing IGF-1R pro-tumorigenic and p53-tumor suppressive signals. This study defines a potent dual-hit strategy: simultaneous control of a tumor-promoter (IGF-1R) and tumor-suppressor (p53), which ultimately mitigates recurrent and metastatic potential, thus opening up targeted therapy to CM.

Syndecans and Their Synstatins: Targeting an Organizer of Receptor Tyrosine Kinase Signaling at the Cell-Matrix Interface

Receptor tyrosine kinases (RTKs) and integrin matrix receptors have well-established roles in tumor cell proliferation, invasion and survival, often functioning in a coordinated fashion at sites of cell-matrix adhesion. Central to this coordination are syndecans, another class of matrix receptor, that organize RTKs and integrins into functional units, relying on docking motifs in the syndecan extracellular domains to capture and localize RTKs (e.g., EGFR, IGF-1R, VEGFR2, HER2) and integrins (e.g., αvβ3, αvβ5, α4β1, α3β1, α6β4) to sites of adhesion. Peptide mimetics of the docking motifs in the syndecans, called “synstatins”, prevent assembly of these receptor complexes, block their signaling activities and are highly effective against tumor cell invasion and survival and angiogenesis. This review describes our current understanding of these four syndecan-coupled mechanisms and their inhibitory synstatins (SSTN_IGF1R, SSTN_VEGFR2, SSTN_VLA-4, SSTN_EGFR and SSTN_HER2).

Insulin/IGF-1 Signaling Is Downregulated in Barrett's Esophagus Patients Undergoing a Moderate Calorie and Protein Restriction Program: A Randomized 2-Year Trial

Obesity and associated insulin resistance (Ins-R) have been identified as important risk factors for esophageal adenocarcinoma development. Elevated calories and protein consumption are also associated with Ins-R and glucose intolerance. We investigated the effect of a 24-month moderate calorie and protein restriction program on overweight or obese patients affected by Barrett’s esophagus (BE), as no similar dietary approach has been attempted to date in this disease context. Anthropometric parameters, levels of serum analytes related to obesity and Ins-R, and the esophageal insulin/IGF-1 signaling pathway were analyzed. This study is registered with ClinicalTrials.gov, number NCT03813381. Insulin, C-peptide, IGF-1, IGF-binding protein 3 (IGFBP3), adipokines, and esophageal expression of the main proteins involved in insulin/IGF-1 signal transduction were quantified using Luminex-XMAP^® technology in 46 patients who followed the restriction program (IA) and in 54 controls (CA). Body mass index and waist circumference significantly decreased in 76.1% of IA and 35.2% of CA. IGF-1 levels were reduced in 71.7% of IA and 51.8% of CA. The simultaneous reduction of glycaemia, IGF-1, the IGF-1/IGFBP3 ratio, and the improvement in weight loss-dependent insulin sensitivity, were associated with the downregulation of the insulin/IGF-1 signal on BE tissue. The proposed intervention program was an effective approach to counteract obesity-associated cancer risk factors. The improvement in metabolic condition resulted in a downregulation of the ERK-mediated mitogenic signal in 43.5% of patients, probably affecting the molecular mechanism driving adenocarcinoma development in BE lesions.

Mechanisms of Drug Resistance and Use of Nanoparticle Delivery to Overcome Resistance in Breast Cancers

Breast cancer is the leading cancer type diagnosed among women in the world. Unfortunately, drug resistance to current breast cancer chemotherapeutics remains the main challenge for a higher survival rate. The recent progress in the nanoparticle platforms and distinct features of nanoparticles that enhance the efficacy of therapeutic agents, such as improved delivery efficacy, increased intracellular cytotoxicity, and reduced side effects, hold great promise to overcome the observed drug resistance. Currently, multifaceted investigations are probing the resistance mechanisms associated with clinical drugs, and identifying new breast cancer-associated molecular targets that may lead to improved therapeutic approaches with the nanoparticle platforms. Nanoparticle platforms including siRNA, antibody-specific targeting and the role of nanoparticles in cellular processes and their effect on breast cancer were discussed in this article.

Modifying Effects of Glucose and Insulin/Insulin-Like Growth Factors on Colon Cancer Cells

There are only a few experimental studies which have investigated effects of glucose alone, and glucose in combination with insulin/insulin-like growth factors (IGF) on the growth of colon cancer. In the present study, we studied in vitro in human colorectal cancer cells originating from four Dukes' stages of colorectal cancer the effects of glucose, insulin and IGFs on proliferation, migration, cell cycle progression and gene expression of the IGF system. Growth of colon cancer cells originating from a Dukes' stage A was glucose-dependent, whereas growth of cancer cells from Dukes' stage B, C and D was glucose-independent. Stimulatory effects of insulin and IGFs on cell growth were observed only in colon cancer cells originating from Dukes' stage C and D. IGF-II stimulated migration in Dukes' stage B cells only. The growth stimulatory effects in Dukes' stage C and D colorectal cancer cells were accompanied by G2/M arrest and associated with an increased IGF-IR/IGF-II receptor ratio. In conclusion, our in vitro data suggest that the stimulating effects of glucose, IGFs and insulin on proliferation differ between colorectal cancer cells from early and late Dukes' stages. Stimulatory effects of glucose on proliferation appear predominantly present in stage Dukes' stage A colorectal cancer cells, while in contrast growth factor-mediated stimulation of cell proliferation is more pronounced in Dukes' late stage (metastasized) colorectal cancer cells. Moreover, our study suggests that a stringent glucose control may be important to control tumor growth in early stages of colorectal cancer, while inhibition of the endocrine actions of the IGFs and insulin become more important in the late (metastasized) stages of colorectal cancer to restrain growth of colon cancer cells.

Insulin-Like Growth Factor 1 (IGF-1) Signaling in Glucose Metabolism in Colorectal Cancer

Colorectal cancer (CRC) is one of the most common aggressive carcinoma types worldwide, characterized by unfavorable curative effect and poor prognosis. Epidemiological data re-vealed that CRC risk is increased in patients with metabolic syndrome (MetS) and its serum components (e.g., hyperglycemia). High glycemic index diets, which chronically raise post-prandial blood glucose, may at least in part increase colon cancer risk via the insulin/insulin-like growth factor 1 (IGF-1) signaling pathway. However, the underlying mechanisms linking IGF-1 and MetS are still poorly understood. Hyperactivated glucose uptake and aerobic glycolysis (the Warburg effect) are considered as a one of six hallmarks of cancer, including CRC. However, the role of insulin/IGF-1 signaling during the acquisition of the Warburg metabolic phenotypes by CRC cells is still poorly understood. It most likely results from the interaction of multiple processes, directly or indirectly regulated by IGF-1, such as activation of PI3K/Akt/mTORC, and Raf/MAPK signaling pathways, activation of glucose transporters (e.g., GLUT1), activation of key glycolytic enzymes (e.g., LDHA, LDH5, HK II, and PFKFB3), aberrant expression of the oncogenes (e.g., MYC, and KRAS) and/or overexpression of signaling proteins (e.g., HIF-1, TGF-β1, PI3K, ERK, Akt, and mTOR). This review describes the role of IGF-1 in glucose metabolism in physiology and colorectal carcinogenesis, including the role of the insulin/IGF system in the Warburg effect. Furthermore, current therapeutic strategies aimed at repairing impaired glucose metabolism in CRC are indicated.

The Olfactory Receptor Gene Product, OR5H2, Modulates Endometrial Cancer Cells Proliferation via Interaction with the IGF1 Signaling Pathway

Endometrial cancer is the most common gynecologic malignancy in Western countries. The insulin-like growth factor-1 (IGF1) axis has an important role in endometrial cancer biology and emerged as a promising therapeutic target in oncology. However, there is an urgent need to identify biomarkers that may help in patient stratification and prognosis. Laron syndrome (LS) is a type of dwarfism that results from the mutation of the growth hormone receptor (GHR) gene, leading to congenital IGF1 deficiency. While high circulating IGF1 is regarded as a risk factor in cancer, epidemiological studies have shown that LS patients are protected from cancer development. Recent genome-wide profilings conducted on LS-derived lymphoblastoid cells led to the identification of a series of genes whose over- or under-representation in this condition might be mechanistically linked to cancer protection. The olfactory receptor 5 subfamily H member 2 (OR5H2) was the top downregulated gene in LS, its expression level being 5.8-fold lower than in the control cells. In addition to their typical role in the olfactory epithelium, olfactory receptors (ORs) are expressed in multiple tissues and play non-classical roles in various pathologies, including cancer. The aim of our study was to investigate the regulation of OR5H2 gene expression by IGF1 in endometrial cancer. Data showed that IGF1 and insulin stimulate OR5H2 mRNA and the protein levels in uterine cancer cell lines expressing either a wild-type or a mutant p53. OR5H2 silencing led to IGF1R downregulation, with ensuing reductions in the downstream cytoplasmic mediators. In addition, OR5H2 knockdown reduced the proliferation rate and cell cycle progression. Analyses of olfr196 (the mouse orthologue of OR5H2) mRNA expression in animal models of GHR deficiency or GH overexpression corroborated the human data. In summary, OR5H2 emerged as a novel target for positive regulation by IGF1, with potential relevance in endometrial cancer.

KLF5-induced lncRNA IGFL2-AS1 promotes basal-like breast cancer cell growth and survival by upregulating the expression of IGFL1

Basal-like breast cancer (BLBC) is the most malignant subtype of breast cancer and has a poor prognosis. Kruppel-like factor 5 (KLF5) is an oncogenic transcription factor in BLBCs. The mechanism by which KLF5 promotes BLBC by regulating the transcription of lncRNAs has not been fully elucidated. In this study, we discovered that lncRNA IGFL2-AS1 is a downstream target gene of KLF5 and that IGFL2-AS1 mediates the pro-proliferation and pro-survival functions of KLF5. Additionally, we demonstrated that IGFL2-AS1 functions by upregulating the transcription of its neighboring gene IGFL1 via two independent mechanisms. On the one hand, nuclear IGFL2-AS1 promotes the formation of a KLF5/TEAD4 transcriptional complex at the IGFL1 gene enhancer. On the other hand, cytoplasmic IGFL2-AS1 inhibits the expression of miR4795-3p, which targets the IGFL1 gene. TNFα induces the expression of IGFL2-AS1 and IGFL1 through KLF5. Taken together, the results of this study indicate that IGFL2-AS1 and IGFL1 may serve as new therapeutic targets for BLBCs.

IGF-1R Transported to the Cell Nuclei to Regulate the Proliferation of Breast Cancer Cells

Under normal physiological conditions, IGF-1 (insulin-like growth factor-1) has important biological effects. However, many studies have found that IGF-1 is closely related to the occurrence and development of breast cancer. But up to now, the cellular properties of IGF-1 have not been systematically explored in breast cancer cell. It is well-known that the cellular properties and behaviors of IGF-1/IGF-1R are closely related to its biological functions. In the current study, we used the breast cancer cell line as a model to explore the biological characteristics of IGF-1/IGF-1R, and found that IGF-1/IGF-1R can be internalized into the cytoplasm. In addition, we also found that IGF-1R can also enter cell nuclei under the mediation of IGF-1. Further research found that the nuclear-localized IGF-1R has important potential biological effects, which is closely associated to the proliferation of breast cancer cell, this may be achieved by regulating IGF-1R-mediated intracellular signaling. The current research has laid the foundation for investigating the relationship between IGF-1/IGF-1R system and the occurrence and development of breast cancer.

YTHDF2 inhibit the tumorigenicity of endometrial cancer via downregulating the expression of IRS1 methylated with m6A

RNA epigenetic modification take part in many biology processes, and the N6-methyladenosine (m⁶A) methylation of specific mRNAs in endometrial cancer (EC) tissues play a key role in regulating the tumorigenicity of EC, but the specific mechanism still unknown and need to be investigated in the future. Here, we found that m⁶A reader protein YTHDF2 expression was significantly upregulated in EC compare to tumor adjacent tissues, YTHDF2 was then identified to inhibit the proliferation and invasion of EC cell lines. Mechanistically, the m⁶A reader YTHDF2 bind the methylation sites of target transcripts IRS1 and promoted IRS1 mRNA degradation, consequently inhibiting the expression of IRS1 and inhibiting IRS1/AKT signaling pathway, finally inhibit the tumorigenicity of EC. Thus, we demonstrated that YTHDF2 inhibited the proliferation and invasion of EC via inhibiting IRS1 expression in m⁶A epigenetic way, which suggests a potential therapeutic target for EC.

IGF-1R nuclear import and recruitment to chromatin involves both alpha and beta subunits

Mature type 1 insulin-like growth factor receptors (IGF-1Rs) are heterotetrameric structures comprising two extracellular α-subunits disulphide-bonded to two transmembrane β-subunits with tyrosine kinase activity. IGF-1R is a well-known cell surface mediator of malignant growth, with an incompletely understood role upon nuclear import as a transcriptional regulator. Previous characterisation of nuclear IGF-1R focused on IGF-1Rβ. Here, we aimed to clarify the source of nuclear IGF-1R and investigate whether α-subunits contribute to nuclear IGF-1R function. Using prostate cancer cell lines DU145 and 22Rv1 we detected nuclear α- and β-subunits, with increase in nuclear signal upon IGF-treatment and reduction in response to IGF-1R inhibitor BMS-754807. Following biotinylation of cell surface proteins, biotinylated α- and β-subunits were detected in nuclear extracts of both cell lines. Furthermore, α- and β-subunits reciprocally co-precipitated from nuclear extract. Finally, we detected recruitment of both subunits to regulatory regions of chromatin, including the promoter of the oncogene JUN, that we previously identified in ChIP-seq as sites of IGF-1Rβ enrichment. These data confirm the cell surface origin of nuclear IGF-1R, suggest the presence of nuclear αβ complexes and reveal that both IGF-1Rα- and β-subunits contribute to pro-tumorigenic functions of nuclear IGF-1R.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12672-021-00407-8.

Biomedical application of chitosan-based nanoscale delivery systems: Potential usefulness in siRNA delivery for cancer therapy

Gene therapy is an emerging and promising strategy in cancer therapy where small interfering RNA (siRNA) system has been deployed for down-regulation of targeted gene and subsequent inhibition in cancer progression; some issues with siRNA, however, linger namely, its off-targeting property and degradation by enzymes. Nanoparticles can be applied for the encapsulation of siRNA thus enhancing its efficacy in gene silencing where chitosan (CS), a linear alkaline polysaccharide derived from chitin, with superb properties such as biodegradability, biocompatibility, stability and solubility, can play a vital role. Herein, the potential of CS nanoparticles has been discussed for the delivery of siRNA in cancer therapy; proliferation, metastasis and chemoresistance are suppressed by siRNA-loaded CS nanoparticles, especially the usage of pH-sensitive CS nanoparticles. CS nanoparticles can provide a platform for the co-delivery of siRNA and anti-tumor agents with their enhanced stability via chemical modifications. As pre-clinical experiments are in agreement with potential of CS-based nanoparticles for siRNA delivery, and these carriers possess biocompatibiliy and are safe, further studies can focus on evaluating their utilization in cancer patients.

The Roles of Insulin-Like Growth Factor Binding Protein Family in Development and Diseases

The insulin-like growth factor (IGF) system comprises ligands of IGF-I/II, IGF receptors (IGFR), IGF binding proteins (IGFBPs), and IGFBP hydrolases. The IGF system plays multiple roles during various disease development as IGFs are widely involved in cell proliferation and differentiation through regulating DNA transcription. Meanwhile, IGFBPs, which are mainly synthesized in the liver, can bind to IGFs and perform two different functions: either inhibition of IGFs by forming inactive compounds with IGF or enhancement of the function of IGFs by strengthening the IGF-IGFR interaction. Interestingly, IGFBPs may have wider functions through IGF-independent mechanisms. Studies have shown that IGFBPs play important roles in cardiovascular disease, tumor progression, fetal growth, and neuro-nutrition. In this review, we emphasize that different IGFBP family members have common or unique functions in numerous diseases; moreover, IGFBPs may serve as biomarkers for disease diagnosis and prediction.

Differential Receptor Tyrosine Kinase Phosphorylation in the Uterus of Rats Following Developmental Exposure to Tetrabromobisphenol A

Tetrabromobisphenol A (TBBPA) is a brominated flame retardant that induces endometrial adenocarcinoma and other uterine tumors in Wistar Han rats; however, early molecular events or biomarkers of TBBPA exposure remain unknown. We investigated the effects of TBBPA on growth factor receptor activation (phospho-RTK) in uteri of rats following early-life exposures. Pregnant Wistar Han rats were exposed to TBBPA (0, 0.1, 25, 250 mg/kg/day) via oral gavage on gestation day 6 through weaning of pups (PND 21). Pups were exposed in utero, through lactation, and by daily gavage from PND 22 to PND 90. Uterine horns were collected (at PND 21, PND 33, PND 90) and formalin-fixed or frozen for histologic, immunohistochemical, phospho-RTK arrays, or western blot analysis. At PND 21, the phosphor-RTKs, FGFR2, FGFR3, TRKC and EPHA1 were significantly increased at different treatment concentrations. Several phospho-RTKs were also significantly overexpressed at PND 33 which included epithelial growth factor receptor (EGFR), Fibroblast Growth Factor Receptor 3-4 (FGFR2, FGFR3, FGFR4), insulin-like growth factor receptor 1 (IGF1R), INSR, AXL, MERTK, PDGFRa and b, RET, Tyrosine Kinase with Immunoglobulin Like and EGF Like Domains 1 and 2 (TIE1; TIE2), TRKA, VEGFR2 and 3, and EPHA1 at different dose treatments. EGFR, an RTK overexpressed in endometrial cancer in women, remained significantly increased for all treatment groups at PND 90. Erb-B2 Receptor Tyrosine Kinase 2 (ERBB2) and IGF1R were overexpressed at PND 33 and remained increased through PND 90, although ERBB2 was statistically significant at PND 90. The phospho-RTKs, FGFR3, AXL, DTK, HGFR, TRKC, VEGFR1 and EPHB2 and 4 were also statistically significant at PND 90 at different dose treatments. The downstream effector, phospho-MAPK44/42 was also increased in uteri of treated rats. Our findings show RTKs are dysregulated following early life TBBPA exposures and their sustained activation may contribute to TBBPA-induced uterine tumors observed in rats later in life.

Laron Syndrome Research Paves the Way for New Insights in Oncological Investigation

Laron syndrome (LS) is a rare genetic endocrinopathy that results from mutation of the growth hormone receptor (GH-R) gene and is typically associated with dwarfism and obesity. LS is the best characterized entity under the spectrum of the congenital insulin-like growth factor-1 (IGF1) deficiencies. Epidemiological analyses have shown that LS patients do not develop cancer, whereas heterozygous family members have a cancer prevalence similar to the general population. To identify genes and signaling pathways differentially represented in LS that may help delineate a biochemical and molecular basis for cancer protection, we have recently conducted a genome-wide profiling of LS patients. Studies were based on our collection of Epstein–Barr virus (EBV)-immortalized lymphoblastoid cell lines derived from LS patients, relatives and healthy controls. Bioinformatic analyses identified differences in gene expression in several pathways, including apoptosis, metabolic control, cytokine biology, Jak-STAT and PI3K-AKT signaling, etc. Genes involved in the control of cell cycle, motility, growth and oncogenic transformation are, in general, down-regulated in LS. These genetic events seem to have a major impact on the biological properties of LS cells, including proliferation, apoptosis, response to oxidative stress, etc. Furthermore, genomic analyses allowed us to identify novel IGF1 downstream target genes that have not been previously linked to the IGF1 signaling pathway. In summary, by ‘mining’ genomic data from LS patients, we were able to generate clinically-relevant information in oncology and, potentially, related disciplines.

Inhibition of G Protein-Coupled Receptor Kinase 2 Promotes Unbiased Downregulation of IGF1 Receptor and Restrains Malignant Cell Growth

The ability of a receptor to preferentially activate only a subset of available downstream signal cascades is termed biased signaling. Although comprehensively recognized for the G protein-coupled receptors (GPCR), this process is scarcely explored downstream of receptor tyrosine kinases (RTK), including the cancer-relevant insulin-like growth factor-1 receptor (IGF1R). Successful IGF1R targeting requires receptor downregulation, yet therapy-mediated removal from the cell surface activates cancer-protective β-arrestin-biased signaling (β-arr-BS). As these overlapping processes are initiated by the β-arr/IGF1R interaction and controlled by GPCR-kinases (GRK), we explored GRKs as potential anticancer therapeutic targets to disconnect IGF1R downregulation and β-arr-BS. Transgenic modulation demonstrated that GRK2 inhibition or GRK6 overexpression enhanced degradation of IGF1R, but both scenarios sustained IGF1-induced β-arr-BS. Pharmacologic inhibition of GRK2 by the clinically approved antidepressant, serotonin reuptake inhibitor paroxetine (PX), recapitulated the effects of GRK2 silencing with dose- and time-dependent IGF1R downregulation without associated β-arr-BS. In vivo, PX treatment caused substantial downregulation of IGF1R, suppressing the growth of Ewing's sarcoma xenografts. Functional studies reveal that PX exploits the antagonism between β-arrestin isoforms; in low ligand conditions, PX favored β-arrestin1/Mdm2-mediated ubiquitination/degradation of IGF1R, a scenario usually exclusive to ligand abundancy, making PX more effective than antibody-mediated IGF1R downregulation. This study provides the rationale, molecular mechanism, and validation of a clinically feasible concept for "system bias" targeting of the IGF1R to uncouple downregulation from signaling. Demonstrating system bias as an effective anticancer approach, our study reveals a novel strategy for the rational design or repurposing of therapeutics to selectively cross-target the IGF1R or other RTK. SIGNIFICANCE: This work provides insight into the molecular and biological roles of biased signaling downstream RTK and provides a novel "system bias" strategy to increase the efficacy of anti-IGF1R-targeted therapy in cancer.

Identification of nephronectin as a new target for IGF1 action

INTRODUCTION

The growth hormone (GH)-insulin-like growth factor-1 (IGF1) endocrine axis has a key role in normal growth and development. Laron syndrome (LS) is a type of dwarfism that results from mutation of the GH receptor, leading to congenital IGF1 deficiency. Epidemiological studies have shown that LS patients are protected from cancer. Genome-wide profiling led to the identification of a series of metabolic genes whose differential expression in LS might be linked to cancer protection. Nephronectin (NPNT) is an intracellular and secreted extracellular matrix protein with important roles in kidney development. NPNT was identified as the top-downregulated gene in LS-derived cells in comparison with ethnic-, age- and gender-matched controls (p-value = 0.0148; fold-change = -3.12 versus controls). NPNT has not been previously linked to the IGF1 signaling pathway. The present study was aimed at evaluating the hypothesis that NPNT is a new target for IGF1 action and that decreased expression of NPNT in LS is correlated with cancer protection.

METHODS

Basal and IGF1-stimulated NPNT expression were assessed in LS lymphoblastoid cells as well as in human breast and prostate cancer cells. NPNT silencing experiments were conducted using siRNA methodology.

RESULTS

We provide evidence that IGF1 stimulates NPNT expression in LS-derived lymphoblastoids and various cancer cell lines. In addition, we demonstrate that NPNT silencing results in diminished activation of the AKT and ERK1/2 pathways, with ensuing decreases in cellular proliferation.

CONCLUSIONS

Our data identified the NPNT gene as a target for IGF1 action. The clinical implications of the functional and physical interactions between NPNT and the IGF1 pathway merit further investigation.

Immunohistochemical expression of insulin-like growth factor-1Ec in primary endometrial carcinoma: Association with PTEN, p53 and survivin expression

Chronic hyperinsulinemia due to insulin resistance and elevated levels of insulin-like growth factor (IGF)-1 and IGF-2 are suggestive of a significantly higher risk of endometrial carcinoma. There is a wealth of evidence showing differential expression of IGF-1 isoforms in various types of cancer. In the present study, 99 archived endometrial carcinoma tissue sections were retrospectively assessed by immunohistochemistry for IGF-1Ec isoform expression. Expression of IGF-1Ec was also assessed in nine cases of non-neoplastic endometrial tissue adjacent to the tumor, in 30 cases with normal endometrium and in 30 cases with endometrial hyperplasia. Furthermore, the association between IGF-1Ec and the concurrent expression of phosphatase and tensin homologue deleted on chromosome 10 (PTEN), p53 or survivin was assessed, as well as their combined expression in association with clinicopathological variables. In endometrial carcinoma, IGF-1Ec expression was high in non-endometrioid carcinoma (serous papillary or clear cell carcinoma) compared with that in endometrioid adenocarcinoma. IGF-1Ec expression was also high in the presence of tumoral necrosis. Furthermore, there was a significant correlation between the histological differentiation and the sum of staining intensity and the number of IGF-1Ec immunopositive cells in endometrial carcinoma. There was a moderate negative correlation between co-expression of IGF-1Ec and PTEN, for both the number of immunopositive cells (P=0.006, ρ=−0.343) and the sum of staining (scores and intensity; P=0.006, ρ=−0.343). Furthermore, there was a positive correlation between the sum of staining (scores and intensity) and co-expression of IGF-1Ec and survivin (P=0.043, ρ=0.225). However, there was no association between concomitant expression of IGF-1Ec and p53. These results emphasized the importance of IGF-1Ec expression during development of non-estrogen dependent endometrial adenocarcinoma. IGF-1Ec and PTEN may function opposingly during endometrial carcinogenesis. By contrast, IGF-1Ec and survivin may share common molecular pathways and may promote, in parallel, tumoral development.

Effects of IGF-1 on Proliferation, Angiogenesis, Tumor Stem Cell Populations and Activation of AKT and Hedgehog Pathways in Oral Squamous Cell Carcinoma

(1) Background: Activation of the PI3K-AKT pathway controls most hallmarks of cancer, and the hedgehog (HH) pathway has been associated with oral squamous cell carcinoma (OSCC) development and progression. We hypothesized that fibroblast-derived insulin-like growth factor-1 (IGF-1) acts in oral squamous cell carcinoma (OSCC) cells, leading to the non-canonical activation of the HH pathway, maintaining AKT activity and promoting tumor aggressiveness. (2) Methods: Primary fibroblasts (MF1) were genetically engineered for IGF-1 overexpression (MF1-IGF1) and CRISPR/Cas9-mediated IGF1R silencing was performed in SCC-4 cells. SCC-4 cells were co-cultured with fibroblasts or incubated with fibroblast conditioned medium (CM) or rIGF-1 for functional assays and the evaluation of AKT and HH pathways. (3) Results: Gene expression analysis confirmed IGF-1 overexpression in MF1-IGF1 and the absence of IGF-1 expression in SCC-4, while elevated IGF1R expression was detected. IGF1R silencing was associated with decreased survival of SCC-4 cells. Ihh was expressed in both MF1 and MF1-IGF1, and increased levels of GLI1 mRNA were observed in SCC-4 after stimulation with CM-MF1. Activation of both PI3K-AKT and the HH pathway (GLI1, Ihh and SMO) were identified in SCC-4 cells cultured in the presence of MF1-IGF1-CM. rIGF-1 promoted tumor cell proliferation, migration, invasion and tumorsphere formation, whereas CM-MF1 significantly stimulated angiogenesis. (4) Conclusions: IGF-1 exerts pro-tumorigenic effects by stimulating SCC-4 cell proliferation, migration, invasion and stemness. AKT and HH pathways were activated by IGF-1 in SCC-4, reinforcing its influence on the regulation of these signaling pathways.

ALKBH5 regulates IGF1R expression to promote the Proliferation and Tumorigenicity of Endometrial Cancer

N6-methyladenosine (m6A) messenger RNA methylation play important role in cell proliferation and tumorigenicity of endometrial cancer, but the key mechanism is not fully clear. Here, we found that RNA demethylase ALKBH5 expression was significantly upregulated in endometrial cancer, ALKBH5 was then identified to positively regulate proliferation and invasion of endometrial cancer. Mechanistically, the m6A eraser ALKBH5 demethylated target transcripts IGF1R and enhanced IGF1R mRNA stability, consequently promoting IGF1R translation and activating IGF1R signaling pathway. Thus, we demonstrated that ALKBH5 promoted proliferation and invasion of endometrial cancer via erasing IGF1R m6A-modifications, which suggests a potential therapeutic target for endometrial cancer.

Gastrointestinal symptoms in acromegaly: A case control study

BACKGROUND

Acromegaly is a chronic disease caused by a pituitary somatotroph adenoma resulting in excess secretion of growth hormone, which leads to excess secretion of Insulin like growth factor 1 from the liver, causing abnormal soft tissue growth. There is increasing awareness that diseases affecting connective tissue are associated with an increase in functional gastrointestinal symptoms. Data was collected from patients with a confirmed diagnosis of acromegaly to evaluate the intensity, variety and impact of abdominal symptoms in comparison with a control group who were healthy participants recruited from the local fracture clinic.

AIM

To evaluate the frequency type and burden of abdominal symptoms in acromegaly in comparison with a control group.

METHODS

Medical documentation of patients with a diagnosis of acromegaly treated in one tertiary medical centre between 2010 and 2017 has been analysed. Data was collected from patients with confirmed acromegaly, using the Short Form Health Survey (SF36) and Rome IV Diagnostic questionnaire for Functional Gastrointestinal Disorders in Adults (R4DQ) and compared to a sex- and age-matched control group, to assess the burden of abdominal symptoms. Microsoft Excel and IBM SPSS v 25 were used for data analysis.

RESULTS

Fifty patients with acromegaly (24 male and 26 females; age range 23-64 years, mean 43) and 200 controls (96 male and 104 females; age range 18-84, mean 42.4) were recruited. 92% (46 out of 50) of patients with acromegaly reported abdominal symptoms and 78% (39 out of 50) had at least one functional gastrointestinal disorder according to the Rome IV diagnostic criteria, compared to 16% of controls (OR > 1, P < 0.0001). The most commonly reported symptom was constipation (69% acromegaly vs 21% of controls OR > 1, P < 0.0001, 95%CI: 4.4–15.8). 34 out of 50 (68%) respondents met the criteria for functional constipation according to Rome IV. Upper gastrointestinal disorders were also more prevalent in the acromegaly group. There was no statistically significant difference in the prevalence of biliary and anorectal symptoms between the two groups. Patients in acromegaly group scored lower on the mean scores of the eight parameters of SF36 Quality of Life questionnaire (mean scores 60.04 vs 71.23, 95%CI: -13.6829 to -8.6971, OR > 1, P < 0.001) as compared to the control group.

CONCLUSION

Upper and lower functional gastrointestinal tract disorders (defined by Rome IV diagnostic criteria) are significantly more prevalent in patients with acromegaly compared with healthy age and sex matched controls in our study. Functional constipation is the most commonly reported problem. Poorer quality of life may in part be attributable to the increased prevalence of abdominal symptoms.

Targeting the IGF-Axis for Cancer Therapy: Development and Validation of an IGF-Trap as a Potential Drug

The insulin-like growth factor (IGF)-axis was implicated in cancer progression and identified as a clinically important therapeutic target. Several IGF-I receptor (IGF-IR) targeting drugs including humanized monoclonal antibodies have advanced to phase II/III clinical trials, but to date, have not progressed to clinical use, due, at least in part, to interference with insulin receptor signaling and compensatory signaling by the insulin receptor (IR) isoform A that can bind IGF-II and initiate mitogenic signaling. Here we briefly review the current state of IGF-targeting biologicals, discuss some factors that may be responsible for their poor performance in the clinic and outline the stepwise bioengineering and validation of an IGF-Trap—a novel anti-cancer therapeutic that could bypass these limitations. The IGF-Trap is a heterotetramer, consisting of the entire extracellular domain of the IGF-IR fused to the Fc portion of human IgG₁. It binds human IGF-I and IGF-II with a three-log higher affinity than insulin and could inhibit IGF-IR driven cellular functions such as survival, proliferation and invasion in multiple carcinoma cell models in vitro. In vivo, the IGF-Trap has favorable pharmacokinetic properties and could markedly reduce metastatic outgrowth of colon and lung carcinoma cells in the liver, outperforming IGF-IR and ligand-binding monoclonal antibodies. Moreover, IGF-Trap dose-response profiles correlate with their bio-availability profiles, as measured by the IGF kinase receptor-activation (KIRA) assay, providing a novel, surrogate biomarker for drug efficacy. Our studies identify the IGF-Trap as a potent, safe, anti-cancer therapeutic that could overcome some of the obstacles encountered by IGF-targeting biologicals that have already been evaluated in clinical settings.

Sphingosine Kinase 1 in Breast Cancer-A New Molecular Marker and a Therapy Target

It is now well-established that sphingosine kinase 1 (SK1) plays a significant role in breast cancer development, progression, and spread, whereas SK1 knockdown can reverse these processes. In breast cancer cells and tumors, SK1 was shown to interact with various pathways involved in cell survival and chemoresistance, such as nuclear factor-kappa B (NFκB), Notch, Ras/MAPK, PKC, and PI3K. SK1 is upregulated by estrogen signaling, which, in turn, confers cancer cells with resistance to tamoxifen. Sphingosine-1-phosphate (S1P) produced by SK1 has been linked to tumor invasion and metastasis. Both SK1 and S1P are closely linked to inflammation and adipokine signaling in breast cancer. In human tumors, high SK1 expression has been linked with poorer survival and prognosis. SK1 is upregulated in triple negative tumors and basal-like subtypes. It is often associated with high phosphorylation levels of ERK1/2, SFK, LYN, AKT, and NFκB. Higher tumor SK1 mRNA levels were correlated with poor response to chemotherapy. This review summarizes the up-to-date evidence and discusses the therapeutic potential for the SK1 inhibition in breast cancer, with emphasis on the mechanisms of chemoresistance and combination with other therapies such as gefitinib or docetaxel. We have outlined four key areas for future development, including tumor microenvironment, combination therapies, and nanomedicine. We conclude that SK1 may have a potential as a target for precision medicine, its high expression being a negative prognostic marker in ER-negative breast cancer, as well as a target for chemosensitization therapy.

Nuclear localization and actions of the insulin-like growth factor 1 (IGF-1) system components: Transcriptional regulation and DNA damage response

Insulin-like growth factor (IGF) system stimulates growth, proliferation, and regulates differentiation of cells in a tissue-specific manner. It is composed of two insulin-like growth factors (IGF-1 and IGF-2), six insulin-like growth factor-binding proteins (IGFBPs), and two insulin-like growth factor receptors (IGF-1R and IGF-2R). IGF actions take place mostly through the activation of the plasma membrane-bound IGF-Rs by the circulating ligands (IGFs) released from the IGFBPs that stabilize their levels in the serum. This review focuses on the IGF-1 part of the system. The IGF-1 gene, which is expressed mainly in the liver as well as in other tissues, comprises six alternatively spliced exons that code for three protein isoforms (pro-IGF-1A, pro-IGF-1B, and pro-IGF-1C), which are processed to mature IGF-1 and E-peptides. The IGF-1R undergoes autophosphorylation, resulting in a signaling cascade involving numerous cytoplasmic proteins such as AKT and MAPKs, which regulate the expression of target genes. However, a more complex picture of the axis has recently emerged with all its components being translocated to the nuclear compartment. IGF-1R takes part in the regulation of gene expression by forming transcription complexes, modifying the activity of chromatin remodeling proteins, and participating in DNA damage tolerance mechanisms. Four IGFBPs contain a nuclear localization signal (NLS), which targets them to the nucleus, where they regulate gene expression (IGFBP-2, IGFBP-3, IGFBP-5, IGFBP-6) and DNA damage repair (IGFBP-3 and IGFBP-6). Last but not least, the IGF-1B isoform has been reported to be localized in the nuclear compartment. However, no specific molecular actions have been assigned to the nuclear pro-IGF-1B or its derivative EB peptide. Therefore, further studies are needed to shed light on their nuclear activity. These recently uncovered nuclear actions of different components of the IGF-1 axis are relevant in cancer cell biology and are discussed in this review.