Insulin/Insulin-like growth factors in cancer: new roles for the aryl hydrocarbon receptor, tumor resistance mechanisms, and new blocking strategies

CircRNAs in Tumor Radioresistance

Circular RNAs (circRNAs) are endogenous, non-coding RNAs, which are derived from host genes that are present in several species and can be involved in the progression of various diseases. circRNAs’ leading role is to act as RNA sponges. In recent years, the other roles of circRNAs have been discovered, such as regulating transcription and translation, regulating host genes, and even being translated into proteins. As some tumor cells are no longer radiosensitive, tumor radioresistance has since become a challenge in treating tumors. In recent years, circRNAs are differentially expressed in tumor cells and can be used as biological markers of tumors. In addition, circRNAs can regulate the radiosensitivity of tumors. Here, we list the mechanisms of circRNAs in glioma, nasopharyngeal carcinoma, and non-small cell lung cancer; further, these studies also provide new ideas for the purposes of eliminating radioresistance in tumors.

Biglycan Interacts with Type I Insulin-like Receptor (IGF-IR) Signaling Pathway to Regulate Osteosarcoma Cell Growth and Response to Chemotherapy

Simple Summary

Osteosarcoma (OS) is an aggressive, primary bone cancer. OS cells produce altered osteoid whose components participate in signaling correlated to the development of this cancer. Biglycan (BGN), a proteoglycan, is correlated to aggressive OS type and resistance to chemotherapy. A constitutive signaling of insulin-like growth factor receptor I (IGF-IR) signaling in sarcoma progression was established. We showed that biglycan binds IGF-IR resulting in prolonged IGF-IR activation, nuclear translocation, and growth response of the poorly-differentiated MG63 cells correlated to increased aggressiveness markers expression and enhanced chemoresistance. This mechanism is not valid in moderately and well-differentiated, biglycan non-expressing U-2OS and Saos-2 OS cells.

Abstract

Osteosarcoma (OS) is a mesenchymally derived, aggressive bone cancer. OS cells produce an aberrant nonmineralized or partly mineralized extracellular matrix (ECM) whose components participate in signaling pathways connected to specific pathogenic phenotypes of this bone cancer. The expression of biglycan (BGN), a secreted small leucine-rich proteoglycan (SLRP), is correlated to aggressive OS phenotype and resistance to chemotherapy. A constitutive signaling of IGF-IR signaling input in sarcoma progression has been established. Here, we show that biglycan activates the IGF-IR signaling pathway to promote MG63 biglycan-secreting OS cell growth by forming a complex with the receptor. Computational models of IGF-IR and biglycan docking suggest that biglycan binds IGF-IR dimer via its concave surface. Our binding free energy calculations indicate the formation of a stable complex. Biglycan binding results in prolonged IGF-IR activation leading to protracted IGF-IR-dependent cell growth response of the poorly-differentiated MG63 cells. Moreover, biglycan facilitates the internalization (p ≤ 0.01, p ≤ 0.001) and sumoylation-enhanced nuclear translocation of IGF-IR (p ≤ 0.05) and its DNA binding in MG63 cells (p ≤ 0.001). The tyrosine kinase activity of the receptor mediates this mechanism. Furthermore, biglycan downregulates the expression of the tumor-suppressor gene, PTEN (p ≤ 0.01), and increases the expression of endothelial–mesenchymal transition (EMT) and aggressiveness markers vimentin (p ≤ 0.01) and fibronectin (p ≤ 0.01) in MG63 cells. Interestingly, this mechanism is not valid in moderately and well-differentiated, biglycan non-expressing U-2OS and Saos-2 OS cells. Furthermore, biglycan exhibits protective effects against the chemotherapeutic drug, doxorubicin, in MG63 OS cells (p ≤ 0.01). In conclusion, these data indicate a potential direct and adjunct therapeutical role of biglycan in osteosarcoma.

Aggravation of pulmonary fibrosis after knocking down the Aryl hydrocarbon receptor in the Insulin-like growth factor 1 receptor pathway

BACKGROUND AND PURPOSE

Idiopathic pulmonary fibrosis (IPF) is a devastating disease with multiple contributing factors. Insulin-like growth factor 1 receptor (IGF1R), with a reciprocal function to Aryl hydrocarbon receptor (AhR), is known to be involved in the development of airway inflammation. However, the exact relationship between IGF1R and AhR in lung fibrogenesis is unclear. This study aimed to investigate the cascade pathway involving IGF1R and AhR in IPF.

EXPERIMENTAL APPROACH

The AhR and IGF1R expressions were determined in the lungs of IPF patients and in a rodent fibrosis model. Pulmonary fibrosis was evaluated in bleomycin (BLM)-induced lung injury in wild type and AhR knockout (AhR^-/- ) mice. The effects of IGF1R inhibition and AhR activation in vitro on TGF-β1-induced epithelial-mesenchymal transition (EMT) in Beas2B cells and in vivo on BLM-exposed mice were also examined.

KEY RESULTS

There were increased IGF1R levels but diminished AhR expression in the lung tissues of IPF patients and BLM-induced mice. Knockout of AhR aggravated lung fibrosis, while the use of IGF1R inhibitor and AhR agonist significantly attenuated such effects and inhibited TGF-β1-induced EMT in Beas2B cells. Both TGF-β1 and BLM markedly suppressed AhR expression through endoplasmic reticulum (ER) stress and consequently, IGF1R activation. The IGF1R inhibitor and specific knockdown of IGF1R reversed the activation of the TGF-β1 signal pathway.

CONCLUSION AND IMPLICATIONS

In the development of IPF, AhR and IGF1R play opposite roles via the TGF-β/Smad/STAT signaling cascade. The AhR/IGF1R axis is a potential target for the treatment of lung injury and fibrosis.

Effect of the Expression of ELOVL5 and IGFBP6 Genes on the Metastatic Potential of Breast Cancer Cells

Breast cancer (BC) is the leading cause of death from malignant neoplasms among women worldwide, and metastatic BC presents the biggest problems for treatment. Previously, it was shown that lower expression of ELOVL5 and IGFBP6 genes is associated with a higher risk of the formation of distant metastases in BC. In this work, we studied the change in phenotypical traits, as well as in the transcriptomic and proteomic profiles of BC cells as a result of the stable knockdown of ELOVL5 and IGFBP6 genes. The knockdown of ELOVL5 and IGFBP6 genes was found to lead to a strong increase in the expression of the matrix metalloproteinase (MMP) MMP1. These results were in good agreement with the correlation analysis of gene expression in tumor samples from patients and were additionally confirmed by zymography. The knockdown of ELOVL5 and IGFBP6 genes was also discovered to change the expression of a group of genes involved in the formation of intercellular contacts. In particular, the expression of the CDH11 gene was markedly reduced, which also complies with the correlation analysis. The spheroid formation assay showed that intercellular adhesion decreased as a result of the knockdown of the ELOVL5 and IGFBP6 genes. Thus, the obtained data indicate that malignant breast tumors with reduced expression of the ELOVL5 and IGFBP6 genes can metastasize with a higher probability due to a more efficient invasion of tumor cells.

Circ-MFN2 Positively Regulates the Proliferation, Metastasis, and Radioresistance of Colorectal Cancer by Regulating the miR-574-3p/IGF1R Signaling Axis

Numerous studies have shown that the expression of circular RNA (circRNA) is closely related to the malignant progression of cancer. However, the role of circ-MFN2 in colorectal cancer (CRC) is unclear. Our study aims to explore the role and mechanism of circ-MFN2 in CRC progression. The relative expression levels of circ-MFN2, microRNA (miR)-574-3p and insulin-like growth factor 1 receptor (IGF1R) were detected by quantitative real-time polymerase chain reaction (qRT-PCR). Cell viability was determined using 3-(4, 5-dimethyl-2 thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT) assay. The colony number and radioresistance of cells were assessed using colony formation assay. Moreover, the migration and invasion of cells were measured using transwell assay. Tumor xenograft model was constructed to evaluate the effect of circ-MFN2 knockdown on CRC tumor growth. Furthermore, dual-luciferase reporter assay was used to verify the interaction between miR-574-3p and circ-MFN2 or IGF1R. In addition, the protein level of IGF1R was evaluated by western blot (WB) analysis. Circ-MFN2 expression was elevated in CRC tissues and cells. Knockdown of circ-MFN2 restrained the proliferation, migration, invasion, and radioresistance of CRC cells in vitro. Furthermore, silenced circ-MFN2 also reduced the tumor volume and weight of CRC in vivo. MiR-574-3p could be sponged by circ-MFN2, and its inhibitor reversed the suppression effect of circ-MFN2 silencing on CRC progression. Moreover, IGF1R was a target of miR-574-3p, and its overexpression reversed the inhibition effect of miR-574-3p mimic on CRC progression. In addition, circ-MFN2 could positively regulate IGF1R expression by sponging miR-574-3p. Our results revealed that circ-MFN2 promoted the proliferation, metastasis and radioresistance of CRC through regulating the miR-574-3p/IGF1R axis, suggesting that circ-MFN2 might be a novel therapeutic biomarker for CRC.

The Role of IGF/IGF-IR-Signaling and Extracellular Matrix Effectors in Bone Sarcoma Pathogenesis

Simple Summary

Bone sarcomas are mesenchymal origin tumors. Bone sarcoma patients show a variable response or do not respond to chemotherapy. Notably, improving efficient chemotherapy approaches, dealing with chemoresistance, and preventing metastasis pose unmet challenges in sarcoma therapy. Insulin-like growth factors 1 and 2 (IGF-1 and -2) and their respective receptors are a multifactorial system that significantly contributes to bone sarcoma pathogenesis. Most clinical trials aiming at the IGF pathway have had limited success. Developing combinatorial strategies to enhance antitumor responses and better classify the patients that could best benefit from IGF-axis targeting therapies is in order. A plausible approach for developing a combinatorial strategy is to focus on the tumor microenvironment (TME) and processes executed therein. Herewith, we will discuss how the interplay between IGF-signaling and the TME constituents affects bone sarcomas’ basal functions and their response to therapy. Potential direct and adjunct therapeutical implications of the extracellular matrix (ECM) effectors will also be summarized.

Abstract

Bone sarcomas, mesenchymal origin tumors, represent a substantial group of varying neoplasms of a distinct entity. Bone sarcoma patients show a limited response or do not respond to chemotherapy. Notably, developing efficient chemotherapy approaches, dealing with chemoresistance, and preventing metastasis pose unmet challenges in sarcoma therapy. Insulin-like growth factors 1 and 2 (IGF-1 and -2) and their respective receptors are a multifactorial system that significantly contributes to bone sarcoma pathogenesis. Whereas failures have been registered in creating novel targeted therapeutics aiming at the IGF pathway, new agent development should continue, evaluating combinatorial strategies for enhancing antitumor responses and better classifying the patients that could best benefit from these therapies. A plausible approach for developing a combinatorial strategy is to focus on the tumor microenvironment (TME) and processes executed therein. Herewith, we will discuss how the interplay between IGF-signaling and the TME constituents affects sarcomas’ basal functions and their response to therapy. This review highlights key studies focusing on IGF signaling in bone sarcomas, specifically studies underscoring novel properties that make this system an attractive therapeutic target and identifies new relationships that may be exploited. Potential direct and adjunct therapeutical implications of the extracellular matrix (ECM) effectors will also be summarized.

Lessons Learned from Targeting IGF-I Receptor in Thyroid-Associated Ophthalmopathy

Complex immunological mechanisms underlie the pathogenesis of thyroid-associated ophthalmopathy (TAO). Historical models of Graves’ disease and TAO have focused almost entirely on autoimmune reactivity directed against the thyrotropin receptor (TSHR). The insulin-like growth factor-I receptor (IGF-IR) has been proposed as a second participating antigen in TAO by virtue of its interactions with IGFs and anti-IGF-IR antibodies generated in Graves’ disease. Furthermore, the IGF-IR forms with TSHR a physical and functional complex which is involved in signaling downstream from both receptors. Inhibition of IGF-IR activity results in attenuation of signaling initiated at either receptor. Based on the aggregate of findings implicating IGF-IR in TAO, the receptor has become an attractive therapeutic target. Recently, teprotumumab, a human monoclonal antibody IGF-IR inhibitor was evaluated in two clinical trials of patients with moderate to severe, active TAO. Those studies revealed that teprotumumab was safe and highly effective in reducing disease activity and severity. Targeting IGF-IR with specific biologic agents may result in a paradigm shift in the therapy of TAO.

Effect of body mass index on response to neo-adjuvant therapy in HER2-positive breast cancer: an exploratory analysis of the NeoALTTO trial

Background

Obesity is a risk factor for breast cancer (BC) development, recurrence, and death. In view of this, we aimed to investigate the clinical value of obesity in BC patients treated with anti-HER2 therapies in the NeoALTTO trial, which randomized 455 patients to neo-adjuvant lapatinib, trastuzumab, or their combination plus paclitaxel.

Methods

Patients were classified according to their basal body mass index (BMI) into underweight (< 18.5 kg/m²), normal (≥ 18.5; < 25 kg/m²), overweight (≥ 25; < 30 kg/m²), and obese (≥ 30 kg/m²) WHO categories. Univariate and multivariate logistic regression analyses were performed using BMI as a categorical variable. Pathological complete response (pCR) and event-free survival (EFS) were the NeoALTTO primary and secondary outcomes, respectively.

Results

Among 454 patients analyzed, 14 (3%), 220 (48%), 137 (30%), and 83 (18%) were classified as underweight, normal weight, overweight, and obese, respectively; 231 (51%) and 223 (49%) had hormone receptor (HR)-positive and HR-negative primary tumors; 160 (35%) achieved pCR. In the overall patient population, no association was found between BMI groups and pCR, as we reported pCR rates of 57.1%, 35%, 30.7%, and 39.8% in underweight, normal weight, overweight, and obese cases, respectively. In contrast, in HR-positive tumors, overweight or obesity was generally associated with decreased likelihood of achieving a pCR independently of other clinical variables, including planned surgery, nodal status, and tumor size (odds ratio [OR] = 0.55, 95%CI 0.30–1.01, as compared to normal or underweight; p = 0.053); notably, no differential effect of BMI with respect to pCR was observed in HR-negative cases (odds ratio [OR] = 1.30, 95%CI 0.76–2.23, as compared to normal or underweight; p = 0.331), resulting in a statistically significant interaction between BMI and HR status (p = 0.036). There was no association between BMI and EFS neither in the overall nor in the HR-positive population, but this analysis was under-powered.

Conclusions

NeoALTTO patients overweight or obese at baseline and with HR-positive primary BC appeared less likely to achieve pCR after neo-adjuvant anti-HER2 therapies. This finding paves the way to future research in targeting the interplay between HER2/HR signaling and metabolism.

Role of Alternatively Spliced Messenger RNA (mRNA) Isoforms of the Insulin-Like Growth Factor 1 (IGF1) in Selected Human Tumors

Insulin-like growth factor 1 (IGF1) is a key regulator of tissue growth and development that is also implicated in the initiation and progression of various cancers. The human IGF1 gene contains six exons and five long introns, the transcription of which is controlled by two promoters (P1 and P2). Alternate promoter usage, as well as alternative splicing (AS) of IGF1, results in the expression of six various variants (isoforms) of mRNA, i.e., IA, IB, IC, IIA, IIB, and IIC. A mature 70-kDa IGF1 protein is coded only by exons 3 and 4, while exons 5 and 6 are alternatively spliced code for the three C-terminal E peptides: Ea (exon 6), Eb (exon 5), and Ec (fragments of exons 5 and 6). The most abundant of those transcripts is IGF1Ea, followed by IGF1Eb and IGF1Ec (also known as mechano-growth factor, MGF). The presence of different IGF1 transcripts suggests tissue-specific auto- and/or paracrine action, as well as separate regulation of both of these gene promoters. In physiology, the role of different IGF1 mRNA isoforms and pro-peptides is best recognized in skeletal muscle tissue. Their functions include the development and regeneration of muscles, as well as maintenance of proper muscle mass. In turn, in nervous tissue, a neuroprotective function of short peptides, produced as a result of IGF1 expression and characterized by significant blood-brain barrier penetrance, has been described and could be a potential therapeutic target. When it comes to the regulation of carcinogenesis, the potential biological role of different var iants of IGF1 mRNAs and pro-peptides is also intensively studied. This review highlights the role of IGF1 isoform expression (mRNAs, proteins) in physiology and different types of human tumors (e.g., breast cancer, cervical cancer, colorectal cancer, osteosarcoma, prostate and thyroid cancers), as well as mechanisms of IGF1 spliced variants involvement in tumor biology.

[Effect of benzo(a)pyrene on the expression of AhR-regulated microRNA in female and male rat lungs]

Smoking is the main risk factor for lung cancer, mainly due to presence of nitrosamines and polycyclic aromatic hydrocarbons, including benzo[a]pyrene (BP) in tobacco smoke composition. The genotoxic effect of BP is based on the high DNA-binding ability of its metabolites, while the epigenetic effects are mediated by a change in the expression of cancer related genes or regulatory RNAs. It has been shown that women have a higher risk to develop lung cancer upon smoking rather than men. We hypothesized that crosstalk between signaling pathways activated by BP and estrogens could underlie the sex-dependent differences in miRNAs expression. To test this hypothesis, male and female rats were subjected to short-term or long-term BP exposure. Using in silico analysis, miRNAs containing the ER- and AhR-binding sites in the promoters of the genes (or host genes) were selected. During chronic exposure of BP the expression of miR-22-3p, -29a-3p, -126a-3p, -193b-5p in the lungs of male rats were significantly increased, while the level of miRNA-483-3p were decreased. Expression of miRNA-483-3p was up-regulated during chronic BP exposure in the lungs of female rats and the levels of other studied miRNAs were unchanged. In turn, changes in the expression of miRNAs were followed by changes in the expression of their target genes, including PTEN, EMP2, IGF1, ITGA6, SLC34A2, and the observed changes in female and male rat lungs were varied. Thus, our results suggest that sex-dependent epigenetic effects of BP may be based on different expression of AhR- and ER- regulated miRNAs.

New Insights from IGF-IR Stimulating Activity Analyses: Pathological Considerations

Insulin-like growth factor-I (IGF-I) and insulin-like growth factor-II (IGF-II) play a crucial factor in the growth, differentiation and survival of cells in health and disease. IGF-I and IGF-II primarily activate the IGF-I receptor (IGF-IR), which is present on the cell surface. Activation of the IGF-IR stimulates multiple pathways which finally results in multiple biological effects in a variety of tissues and cells. In addition, activation of the IGF-IR has been found to be essential for the growth of cancers. The conventional view in the past was that the IGF-IR was exclusively a tyrosine kinase receptor and that phosphorylation of tyrosine residues, after binding of IGF-I to the IGF-IR, started a cascade of post-receptor events. Recent research has shown that this view was too simplistic. It has been found that the IGF-IR also has kinase-independent functions and may even emit signals in the unoccupied state through some yet-to-be-defined non-canonical pathways. The IGF-IR may further form hybrids with the insulin receptors but also with receptor tyrosine kinases (RTKs) outside the insulin-IGF system. In addition, the IGF-IR has extensive cross-talk with many other receptor tyrosine kinases and their downstream effectors. Moreover, there is now emerging evidence that the IGF-IR utilizes parts of the G-protein coupled receptor (GPCR) pathways: the IGF-IR can be considered as a functional RTK/GPCR hybrid, which integrates the kinase signaling with some IGF-IR mediated canonical GPCR characteristics. Like the classical GPCRs the IGF-IR can also show homologous and heterologous desensitization. Recently, it has been found that after activation by a ligand, the IGF-IR may be translocated into the nucleus and function as a transcriptional cofactor. Thus, in recent years, it has become clear that the IGF-IR signaling pathways are much more complex than first thought. Therefore a big challenge for the (near) future will be how all the new knowledge about IGF-IR signaling can be translated into the clinical practice and improve diagnosis and treatment of diseases.

The fasting blood glucose and long non-coding RNA SNHG8 predict poor prognosis in patients with gastric carcinoma after radical gastrectomy

This prospective study sought to evaluate the prediction of fasting blood glucose and long non-coding RNA (lncRNA) SNHG8 for the risk of gastric carcinoma mortality. A total of 217 gastric carcinoma patients underwent radical gastrectomy were included during 2012-16. The final follow-up was finished in January 2017. The aggregate hazard ratio(HR) demonstrated that poor prognosis of gastric carcinoma was associated with fasting blood glucose (HR= 1.29, P=0.037), SNHG8 expression(HR = 1.10, P= 0.009), positive distant metastasis(HR = 2.99, P= 0.020), EBV positive (HR = 3.40, P=0.002), and tumor size more than 5.0 cm (HR = 3.36, P= 0.005). In survival analysis, elevated fasting blood glucose (P =0.007) and high SNHG8 expression (P =0.007) were significantly associated with shorter survival times in gastric cancer. Significant multiplicative interaction was shown between fasting blood glucose and SNHG8 expression (chi-squared=7.81, P_{multiplicative} =0.005), without statistical additive interaction. Fasting blood glucose and SNHG8 expression could predict poor prognosis after radical gastrectomy. LncRNA SNHG8 could be applied as a novel epigenetic molecular target in gastric carcinoma.

Competitive Endogenous RNA Network Construction and Comparison of Lung Squamous Cell Carcinoma in Smokers and Nonsmokers

Background

Lung squamous cell carcinoma (LUSC) is a subtype of highly malignant lung cancer with poor prognosis, for which smoking is the main risk factor. However, the underlying genetic and molecular mechanisms of smoking-related LUSC remain largely unknown.

Methods

We mined existing LUSC-related mRNA, miRNA, and lncRNA transcriptome data and corresponding clinical data from The Cancer Genome Atlas (TCGA) database and divided them into smoking and nonsmoking groups, followed by differential expression analysis. Functional enrichment analysis of the unique differentially expressed mRNAs of the two groups was performed using the DAVID database. Subsequently, the lncRNA-miRNA-mRNA competing endogenous RNA (ceRNA) network of LUSC in smoking and nonsmoking groups was constructed. Finally, survival analyses were performed to determine the effects of differentially expressed lncRNAs/mRNAs/miRNAs that were involved in the ceRNA network on overall survival and to discover the hub genes.

Results

A total of 1696 lncRNAs, 125 miRNAs, and 3246 mRNAs and 1784 lncRNAs, 96 miRNAs, and 3229 mRNAs with differentially expressed profiles were identified in the smoking and nonsmoking groups, respectively. The ceRNA network and survival analysis revealed four lncRNAs (LINC00466, DLX6-AS1, LINC00261, and AGBL1), one miRNA (hsa-mir-210), and two mRNAs (CITED2 and ENPP4), with the potential as biomarkers for smoking-related LUSC diagnosis and prognosis.

Conclusion

Taken together, our research has identified the differences in the ceRNA regulatory networks between smoking and nonsmoking LUSC, which could lay the foundation for future clinical research.

Dietary natural flavonoids treating cancer by targeting aryl hydrocarbon receptor

The role of aryl hydrocarbon receptor (AhR) as a ligand-activated transcription factor in the field of cancer has gradually been unveiled. A strong body of evidence indicated that AhR is implicated in cell proliferation and apoptosis, immune metabolism and other processes, which further affected tumor growth, survival, migration, and invasion. Therefore, AhR targeted therapy may become a new method for cancer treatment and provide a new direction for clinical tumor treatment. Astonishingly, the largest source of exposure of animals and humans to AhR ligands (synthetic and natural) comes from the diet. Myriad studies have described that various natural dietary chemicals can directly activate and/or inhibit the AhR signaling pathway. Of note, numerous natural products contribute to AhR active, of which dietary flavonoids are the largest class of natural AhR ligands. As interest in AhR and its ligands increases, it seems sensible to summarize current research on these ligands. In this review, we highlight the role of AhR in tumorigenesis and focus on the double effect of AhR in cancer therapy. We explored the molecular mechanism of AhR ligands on cancer through a few AhR agonists/antagonists currently in clinical practice. Ultimately, we summarize and highlight the latest progression of dietary flavonoids as AhR ligands in cancer inhibition, including the limitations and deficiencies of it in clinical research. This review will offer a comprehensive understanding of AhR and its dietary ligands which may dramatically pave the way for targeted cancer treatment.

High Glucose Concentrations Negatively Regulate the IGF1R/Src/ERK Axis through the MicroRNA-9 in Colorectal Cancer

Studies have revealed that people with hyperglycemia have a high risk of colorectal cancer (CRC). Hyperglycemia may be responsible for supplying energy to CRC cells. However, the potential molecular mechanism for this association remains unclear. Furthermore, microRNA-9 (miR-9) has a tumor-suppressive function in CRC. Aberrant reduced expression of miR-9 is involved in the development and progression of malignancy caused by a high glucose (HG) concentration. In this study, we used an HG concentration to activate miR-9 downregulation in CRC cells. Our results indicated that miR-9 decreased the insulin-like growth factor-1 receptor (IGF1R)/Src signaling pathway and downstream cyclin B1 and N-cadherin but upregulated E-cadherin. The HG concentration not only promoted cell proliferation, increased the G1 population, and modulated epithelial-to-mesenchymal transition (EMT) protein expression and morphology but also promoted the cell migration and invasion ability of SW480 (low metastatic potential) and SW620 (high metastatic potential) cells. In addition, low glucose concentrations could reverse the effect of the HG concentration in SW480 and SW620 cells. In conclusion, our results provide new evidence for multiple signaling pathways being regulated through hyperglycemia in CRC. We propose that blood sugar control may serve as a potential strategy for the clinical management of CRC.

Diabetes, Obesity, and Breast Cancer

The rates of obesity and diabetes are increasing worldwide, whereas the age of onset for both obesity and diabetes are decreasing steadily. Obesity and diabetes are associated with multiple factors that contribute to the increased risk of a number of different cancers, including breast cancer. These factors are hyperinsulinemia, elevated IGFs, hyperglycemia, dyslipidemia, adipokines, inflammatory cytokines, and the gut microbiome. In this review, we discuss the current understanding of the complex signaling pathways underlying these multiple factors involved in the obesity/diabetes-breast cancer link, with a focus particularly on the roles of the insulin/IGF system and dyslipidemia in preclinical breast cancer models. We review some of the therapeutic strategies to target these metabolic derangements in cancer. Future research directions and potential therapeutic strategies are also discussed.

Suppression of cleavage factor Im 25 promotes the proliferation of lung cancer cells through alternative polyadenylation

BACKGROUND

Non-small cell lung cancer (NSCLC) is a life-threatening disease that has a poor prognosis and low survival rate. Cleavage factor Im 25 (CFIm25) is a RNA-binding protein that if down-regulated causes 3'UTR shortening and thus promotes the transcript stability of target genes. It is not clear whether CFIm25 and alternative polyadenylation (APA) play a role during cancer development. The purpose of this study is to explore the role of CFIm25 in lung cancer cell proliferation.

METHODS

CFIm25 was knocked down in A549 cells. Western blots were carried out to determine the protein expression of CFIm25, insulin growth factor 1 receptor (IGF1R), CyclinD1 (CCND1) and TP53. Real-time qRT PCR was performed to determine the total transcript levels of CFIm25 targets and the normalized fold changes in their distal PAS (dPAS) usage. Immunofluorescence was carried out to check the expression of CFIm25, IGF1R and CCND1. Cell proliferation over time was determined using the WST-1 reagent.

RESULTS

The transcript levels of CCND1 and GSK3β were significantly increased and the dPAS usage of several oncogenes (IGF1R, CCND1 and GSK3β) were decreased after CFIm25 knockdown. The protein level of IGF1R was increased, and we detected increased percentage of CCND1 positive cells and cell proliferation over time in CFIm25 knockdown cells. In addition, the mRNA and APA analysis of IGF1R using patient RNA-seq data from the Cancer Genome Atlas indicated that IGF1R is shortened in both lung adenocarcinoma and lung squamous cell carcinoma compared to normal controls.

CONCLUSIONS

Our findings suggest that CFIm25 plays an important role in lung cancer cell proliferation through regulating the APA of oncogenes, including IGF1R, and promoting their protein expression.

Receptors for Insulin-Like Growth Factor-2 and Androgens as Therapeutic Targets in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) occurs in 10-15% of all breast cancer patients, yet it accounts for about half of all breast cancer deaths. There is an urgent need to identify new antitumor targets to provide additional treatment options for patients afflicted with this aggressive disease. Preclinical evidence suggests a critical role for insulin-like growth factor-2 (IGF2) and androgen receptor (AR) in regulating TNBC progression. To advance this work, a panel of TNBC cell lines was investigated with all cell lines showing significant expression of IGF2. Treatment with IGF2 stimulated cell proliferation in vitro (p < 0.05). Importantly, combination treatments with IGF1R inhibitors BMS-754807 and NVP-AEW541 elicited significant inhibition of TNBC cell proliferation (p < 0.001). Based on Annexin-V binding assays, BMS-754807, NVP-AEW541 and enzalutamide induced TNBC cell death (p < 0.005). Additionally, combination of enzalutamide with BMS-754807 or NVP-AEW541 exerted significant reductions in TNBC proliferation even in cells with low AR expression (p < 0.001). Notably, NVP-AEW541 and BMS-754807 reduced AR levels in BT549 TNBC cells. These results provide evidence that IGF2 promotes TNBC cell viability and proliferation, while inhibition of IGF1R/IR and AR pathways contribute to blockade of TNBC proliferation and promotion of apoptosis in vitro.

FGF1 and IGF1-conditioned 3D culture system promoted the amplification and cancer stemness of lung cancer cells

Lung cancer stem cells (LCSCs) are considered as the cellular origins of metastasis and relapse of lung cancer. However, routine two-dimensional culture system (2D-culture) hardly mimics the growth and functions of LCSCs in vivo and therefore significantly decreases the stemness activity of LCSCs. In this study, we constructed a special BME-based three-dimensional culture system (3D-culture) to amplify LCSCs in human lung adenocarcinoma cell line A549 cells and found 3D-culture promoted the enrichment and amplification of LCSCs in A549 cells displaying higher proliferation potential and invasion activity, but lower apoptosis. The expression and secretion levels of FGF1 and IGF1 were dramatically elevated in 3D-culture compared to 2D-culture. After growing in FGF1 and IGF1-conditioned 3D-culture, the proportion of LCSCs with specific stemness phenotypes in A549 cells significantly increased compared to that in conventional 3D suspension culture system. Further results indicated that FGF1 and IGF1 promoted the amplification and cancer stemness of LCSCs dependent on MAPK signaling pathway. Our data firstly established a growth factors-conditioned 3D-culture for LCSCs and demonstrated the effects of FGF1 and IGF1 in promoting the enrichment and amplification of LCSCs which might provide a feasible cell model in vitro for both mechanism study and translational research on lung cancer.

Paclitaxel-mediated human aryl hydrocarbon receptor mRNA translation by an internal ribosomal entry site-dependent mechanism

The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that is best known in mediating the toxicities of dioxins and dioxin-like compounds. AHR is activated by a variety of endogenous ligands and participating in tumor development. Thus, it will provide a new approach for cancer prevention and treatment to study the translation mechanism of AHR in tumor cells. In this study, we show that the 5'-untranslated region (UTR) of AHR mRNA contains an internal ribosome entry site (IRES). After mapping the entire AHR 5'-UTR, we determined that the full-length 5'-UTR is indispensable for the highest IRES activity. Interestingly, we found that AHR expression is induced in ovarian (A2780), breast (MDA-MB231), hepatic (Bel7402) and colorectal cancer cells (SW620) by chemotherapeutic drug paclitaxel (PTX) through IRES-dependent translation mechanism. Moreover, IRES activity is increased in the PTX-resistant ovarian cancer cells in which AHR protein expression was also enhanced. These results strongly suggest an important role for AHR IRES-dependent translation mechanism in cancer cell response to paclitaxel treatment.

Preoperative Metabolic Syndrome Is Predictive of Significant Gastric Cancer Mortality after Gastrectomy: The Fujian Prospective Investigation of Cancer (FIESTA) Study

Metabolic syndrome (MetS) has been shown to be associated with an increased risk of gastric cancer. However, the impact of MetS on gastric cancer mortality remains largely unknown. Here, we prospectively examined the prediction of preoperative MetS for gastric cancer mortality by analyzing a subset of data from the ongoing Fujian prospective investigation of cancer (FIESTA) study. This study was conducted among 3012 patients with gastric cancer who received radical gastrectomy between 2000 and 2010. The latest follow-up was completed in 2015. Blood/tissue specimens, demographic and clinicopathologic characteristics were collected at baseline. During 15-year follow-up, 1331 of 3012 patients died of gastric cancer. The median survival time (MST) of patients with MetS was 31.3months, which was significantly shorter than that of MetS-free patients (157.1months). The coexistence of MetS before surgery was associated with a 2.3-fold increased risk for gastric cancer mortality (P<0.001). The multivariate-adjusted hazard ratios (HRs) were increased with invasion depth T1/T2 (HR=2.78, P<0.001), regional lymph node metastasis N0 (HR=2.65, P<0.001), positive distant metastasis (HR=2.53, P<0.001), TNM stage I/II (HR=3.00, P<0.001), intestinal type (HR=2.96, P<0.001), negative tumor embolus (HR=2.34, P<0.001), and tumor size ≤4.5cm (HR=2.49, P<0.001). Further survival tree analysis confirmed the top splitting role of TNM stage, followed by MetS or hyperglycemia with remarkable discrimination ability. In this large cohort study, preoperative MetS, especially hyperglycemia, was predictive of significant gastric cancer mortality in patients with radical gastrectomy, especially for early stage of gastric cancer.

Biased signalling is an essential feature of TLR4 in glioma cells

A distinct feature of the Toll-like receptor 4 (TLR4) is its ability to trigger both MyD88-dependent and MyD88-independent signalling, culminating in activation of pro-inflammatory NF-κB and/or the antiviral IRF3. Although TLR4 agonists (lipopolysaccharides; LPSs) derived from different bacterial species have different endotoxic activity, the impact of LPS chemotype on the downstream signalling is not fully understood. Notably, different TLR4 agonists exhibit anti-tumoural activity in animal models of glioma, but the underlying molecular mechanisms are largely unknown. Thus, we investigated the impact of LPS chemotype on the signalling events in the human glioma cell line U251. We found that LPS of Escherichia coli origin (LPS_EC) leads to NF-κB-biased downstream signalling compared to Salmonella minnesota-derived LPS (LPS_SM). Exposure of U251 cells to LPS_EC resulted in faster nuclear translocation of the NF-κB subunit p65, higher NF-κB-activity and expression of its targets genes, and higher amount of secreted IL-6 compared to LPS_SM. Using super-resolution microscopy we showed that the biased agonism of TLR4 in glioma cells is neither a result of differential regulation of receptor density nor of formation of higher order oligomers. Consistent with previous reports, LPS_EC-mediated NF-κB activation led to significantly increased U251 proliferation, whereas LPS_SM-induced IRF3 activity negatively influenced their invasiveness. Finally, treatment with methyl-β-cyclodextrin (MCD) selectively increased LPS_SM-induced nuclear translocation of p65 and NF-κB activity without affecting IRF3. Our data may explain how TLR4 agonists differently affect glioma cell proliferation and migration.

Understanding STAT3 signaling in cardiac ischemia

Cardiovascular disease is the leading cause of death worldwide. It remains one of the greatest challenges to global health and will continue to dominate mortality trends in the future. Acute myocardial infarction results in 7.4 million deaths globally per annum. Current management strategies are centered on restoration of coronary blood flow via percutaneous coronary intervention, coronary artery bypass grafting and administration of anti-platelet agents. Such myocardial reperfusion accounts for 40-50 % of the final infarct size in most cases. Signaling transducer and activator of transcription 3 (STAT3) has been shown to have cardioprotective effects via canonical and non-canonical activation and modulation of mitochondrial and transcriptional responses. A significant body of in vitro and in vivo evidence suggests that activation of the STAT3 signal transduction pathway results in a cardio protective response to ischemia and attempts have been made to modulate this with therapeutic effect. Not only is STAT3 important for cardiomyocyte function, but it also modulates the cardiac microenvironment and communicates with cardiac fibroblasts. To this end, we here review the current evidence supporting the manipulation of STAT3 for therapeutic benefit in cardiac ischemia and identify areas for future research.

Homology modeling and docking studies of ENPP4: a BCG activated tumoricidal macrophage protein

BACKGROUND

The 3D structure and functions of ENPP4, a protein expressed on the surface of Bacillus Calmette-Guerin (BCG)-activated macrophages, are unknown. In this study, we analyzed the 3D structure of ENPP4 and determined its tumoricidal effects on MCA207 cells.

RESULTS

Homology modeling showed that Arg305, Tyr341, Asn291, and Asn295 are important residues in substrate, adenosine triphosphate (ATP), binding. A molecular dynamics study was also carried out to study the stability of ENPP4 (including zinc atoms) as well as its ligand-enzyme complex. BCG increased ENPP4 expression in macrophages, and specific blocking of ENPP4 in BCG-activated macrophages (BAMs) significantly reduced their cytotoxicity against MCA207 cells.

CONCLUSIONS

These results indicate that zinc remains inside the ENPP4 protein, a BCG activated tumoricidal macrophage protein, throughout the simulation. Important information for the design of new inhibitors was obtained.