Downregulation of insulin-like growth factor-binding protein 7 in cisplatin-resistant non-small cell lung cancer

Identification of New Chemoresistance-Associated Genes in Triple-Negative Breast Cancer by Single-Cell Transcriptomic Analysis

Triple-negative breast cancer (TNBC) is a particularly aggressive mammary neoplasia with a high fatality rate, mainly because of the development of resistance to administered chemotherapy, the standard treatment for this disease. In this study, we employ both bulk RNA-sequencing and single-cell RNA-sequencing (scRNA-seq) to investigate the transcriptional landscape of TNBC cells cultured in two-dimensional monolayers or three-dimensional spheroids, before and after developing resistance to the chemotherapeutic agents paclitaxel and doxorubicin. Our findings reveal significant transcriptional heterogeneity within the TNBC cell populations, with the scRNA-seq identifying rare subsets of cells that express resistance-associated genes not detected by the bulk RNA-seq. Furthermore, we observe a partial shift towards a highly mesenchymal phenotype in chemoresistant cells, suggesting the epithelial-to-mesenchymal transition (EMT) as a prevalent mechanism of resistance in subgroups of these cells. These insights highlight potential therapeutic targets, such as the PDGF signaling pathway mediating EMT, which could be exploited in this setting. Our study underscores the importance of single-cell approaches in understanding tumor heterogeneity and developing more effective, personalized treatment strategies to overcome chemoresistance in TNBC.

Exosomal Serum Biomarkers as Predictors for Laryngeal Carcinoma

BACKGROUND

The lack of screening methods for LSCC is a critical issue, as treatment options and the treatment outcome greatly depend on the stage of LSCC at initial diagnosis. Therefore, the objective of this study was to identify potential exosomal serum biomarkers that can diagnose LSCC and distinguish between early- and late-stage disease.

METHODS

A multiplexed proteomic array was used to identify differentially expressed proteins in exosomes isolated from the serum samples of LSCC patients compared to the control group (septorhinoplasty, SRP). The most promising proteins for diagnosis and differentiation were calculated using biostatistical methods and were validated by immunohistochemistry (IHC), Western blots (WB), and ELISA.

RESULTS

Exosomal insulin-like growth factor binding protein 7 (IGFBP7) and Annexin A1 (ANXA1) were the most promising exosomal biomarkers for distinguishing between control and LSCC patients and also between different stages of LSCC (fold change up to 15.9, p < 0.001 for all).

CONCLUSION

The identified proteins represent potentially novel non-invasive biomarkers. However, these results need to be validated in larger cohorts with a long-term follow-up. Exosomal biomarkers show a superior signal-to-noise ratio compared to whole serum and may therefore be an important tool for non-invasive biomarker profiling for laryngeal carcinoma in the future.

Single-Cell RNA Sequencing Identifies Response of Renal Lymphatic Endothelial Cells to Acute Kidney Injury

SIGNIFICANCE STATEMENT

The renal lymphatic vasculature and the lymphatic endothelial cells that make up this network play important immunomodulatory roles during inflammation. How lymphatics respond to AKI may affect AKI outcomes. The authors used single-cell RNA sequencing to characterize mouse renal lymphatic endothelial cells in quiescent and cisplatin-injured kidneys. Lymphatic endothelial cell gene expression changes were confirmed in ischemia-reperfusion injury and in cultured lymphatic endothelial cells, validating renal lymphatic endothelial cells single-cell RNA sequencing data. This study is the first to describe renal lymphatic endothelial cell heterogeneity and uncovers molecular pathways demonstrating lymphatic endothelial cells regulate the local immune response to AKI. These findings provide insights into previously unidentified molecular pathways for lymphatic endothelial cells and roles that may serve as potential therapeutic targets in limiting the progression of AKI.

BACKGROUND

The inflammatory response to AKI likely dictates future kidney health. Lymphatic vessels are responsible for maintaining tissue homeostasis through transport and immunomodulatory roles. Owing to the relative sparsity of lymphatic endothelial cells in the kidney, past sequencing efforts have not characterized these cells and their response to AKI.

METHODS

Here, we characterized murine renal lymphatic endothelial cell subpopulations by single-cell RNA sequencing and investigated their changes in cisplatin AKI 72 hours postinjury. Data were processed using the Seurat package. We validated our findings by quantitative PCR in lymphatic endothelial cells isolated from both cisplatin-injured and ischemia-reperfusion injury, by immunofluorescence, and confirmation in in vitro human lymphatic endothelial cells.

RESULTS

We have identified renal lymphatic endothelial cells and their lymphatic vascular roles that have yet to be characterized in previous studies. We report unique gene changes mapped across control and cisplatin-injured conditions. After AKI, renal lymphatic endothelial cells alter genes involved in endothelial cell apoptosis and vasculogenic processes as well as immunoregulatory signaling and metabolism. Differences between injury models were also identified with renal lymphatic endothelial cells further demonstrating changed gene expression between cisplatin and ischemia-reperfusion injury models, indicating the renal lymphatic endothelial cell response is both specific to where they lie in the lymphatic vasculature and the kidney injury type.

CONCLUSIONS

In this study, we uncover lymphatic vessel structural features of captured populations and injury-induced genetic changes. We further determine that lymphatic endothelial cell gene expression is altered between injury models. How lymphatic endothelial cells respond to AKI may therefore be key in regulating future kidney disease progression.

Angiogenesis modulated by CD93 and its natural ligands IGFBP7 and MMRN2: a new target to facilitate solid tumor therapy by vasculature normalization

The tumor vasculature was different from the normal vasculature in both function and morphology, which caused hypoxia in the tumor microenvironment (TME). Previous anti-angiogenesis therapy had led to a modest improvement in cancer immunotherapy. However, antiangiogenic therapy only benefitted a few patients and caused many side effects. Therefore, there was still a need to develop a new approach to affect tumor vasculature formation. The CD93 receptor expressed on the surface of vascular endothelial cells (ECs) and its natural ligands, MMRN2 and IGFBP7, were now considered potential targets in the antiangiogenic treatment because recent studies had reported that anti-CD93 could normalize the tumor vasculature without impacting normal blood vessels. Here, we reviewed recent studies on the role of CD93, IGFBP7, and MMRN2 in angiogenesis. We focused on revealing the interaction between IGFBP7-CD93 and MMRN2-CD93 and the signaling cascaded impacted by CD93, IGFBP7, and MMRN2 during the angiogenesis process. We also reviewed retrospective studies on CD93, IGFBP7, and MMRN2 expression and their relationship with clinical factors. In conclusion, CD93 was a promising target for normalizing the tumor vasculature.

Single-cell RNA sequencing identifies response of renal lymphatic endothelial cells to acute kidney injury

The inflammatory response to acute kidney injury (AKI) likely dictates future renal health. Lymphatic vessels are responsible for maintaining tissue homeostasis through transport and immunomodulatory roles. Due to the relative sparsity of lymphatic endothelial cells (LECs) in the kidney, past sequencing efforts have not characterized these cells and their response to AKI. Here we characterized murine renal LEC subpopulations by single-cell RNA sequencing and investigated their changes in cisplatin AKI. We validated our findings by qPCR in LECs isolated from both cisplatin-injured and ischemia reperfusion injury, by immunofluorescence, and confirmation in in vitro human LECs. We have identified renal LECs and their lymphatic vascular roles that have yet to be characterized in previous studies. We report unique gene changes mapped across control and cisplatin injured conditions. Following AKI, renal LECs alter genes involved endothelial cell apoptosis and vasculogenic processes as well as immunoregulatory signaling and metabolism. Differences between injury models are also identified with renal LECs further demonstrating changed gene expression between cisplatin and ischemia reperfusion injury models, indicating the renal LEC response is both specific to where they lie in the lymphatic vasculature and the renal injury type. How LECs respond to AKI may therefore be key in regulating future kidney disease progression.

IGFBP-6 Network in Chronic Inflammatory Airway Diseases and Lung Tumor Progression

The lung is an accomplished organ for gas exchanges and directly faces the external environment, consequently exposing its large epithelial surface. It is also the putative determinant organ for inducing potent immune responses, holding both innate and adaptive immune cells. The maintenance of lung homeostasis requires a crucial balance between inflammation and anti-inflammation factors, and perturbations of this stability are frequently associated with progressive and fatal respiratory diseases. Several data demonstrate the involvement of the insulin-like growth factor (IGF) system and their binding proteins (IGFBPs) in pulmonary growth, as they are specifically expressed in different lung compartments. As we will discuss extensively in the text, IGFs and IGFBPs are implicated in normal pulmonary development but also in the pathogenesis of various airway diseases and lung tumors. Among the known IGFBPs, IGFBP-6 shows an emerging role as a mediator of airway inflammation and tumor-suppressing activity in different lung tumors. In this review, we assess the current state of IGFBP-6's multiple roles in respiratory diseases, focusing on its function in the inflammation and fibrosis in respiratory tissues, together with its role in controlling different types of lung cancer.

The role of IGF-pathway biomarkers in determining risks, screening, and prognosis in lung cancer

Background: Detection rates of early-stage lung cancer are traditionally low, which contributes to inconsistent treatment responses and high rates of annual cancer deaths. Currently, low-dose computed tomography (LDCT) screening produces a high false discovery rate. This limitation has prompted research to identify biomarkers to more clearly define eligible patients for LDCT screening, differentiate indeterminate pulmonary nodules, and select individualized cancer therapy. Biomarkers within the Insulin-like Growth Factor (IGF) family have come to the forefront of this research.

Main Body: Multiple biomarkers within the IGF family have been investigated, most notably IGF-I and IGF binding protein 3. However, newer studies seek to expand this search to other molecules within the IGF axis. Certain studies have demonstrated these biomarkers are useful when used in combination with lung cancer screening, but other findings were not as conclusive, possibly owing to measurement bias and non-standardized assay techniques. Research also has suggested IGF biomarkers may be beneficial in the prognostication and subsequent treatment via systemic therapy. Despite these advances, additional knowledge of complex regulatory mechanisms inherent to this system are necessary to more fully harness the potential clinical utility for diagnostic and therapeutic purposes.

Conclusions: The IGF system likely plays a role in multiple phases of lung cancer; however, there is a surplus of conflicting data, especially prior to development of the disease and during early stages of detection. IGF biomarkers may be valuable in the screening, prognosis, and treatment of lung cancer, though their exact application requires further study.

Identification of a novel gene signature predicting response to first-line chemotherapy in BRCA wild-type high-grade serous ovarian cancer patients

BACKGROUND

High-grade serous ovarian cancer (HGSOC) has poor survival rates due to a combination of diagnosis at advanced stage and disease recurrence as a result of chemotherapy resistance. In BRCA1 (Breast Cancer gene 1) - or BRCA2-wild type (BRCAwt) HGSOC patients, resistance and progressive disease occur earlier and more often than in mutated BRCA. Identification of biomarkers helpful in predicting response to first-line chemotherapy is a challenge to improve BRCAwt HGSOC management.

METHODS

To identify a gene signature that can predict response to first-line chemotherapy, pre-treatment tumor biopsies from a restricted cohort of BRCAwt HGSOC patients were profiled by RNA sequencing (RNA-Seq) technology. Patients were sub-grouped according to platinum-free interval (PFI), into sensitive (PFI > 12 months) and resistant (PFI < 6 months). The gene panel identified by RNA-seq analysis was then tested by high-throughput quantitative real-time PCR (HT RT-qPCR) in a validation cohort, and statistical/bioinformatic methods were used to identify eligible markers and to explore the relevant pathway/gene network enrichments of the identified gene set. Finally, a panel of primary HGSOC cell lines was exploited to uncover cell-autonomous mechanisms of resistance.

RESULTS

RNA-seq identified a 42-gene panel discriminating sensitive and resistant BRCAwt HGSOC patients and pathway analysis pointed to the immune system as a possible driver of chemotherapy response. From the extended cohort analysis of the 42 DEGs (differentially expressed genes), a statistical approach combined with the random forest classifier model generated a ten-gene signature predictive of response to first-line chemotherapy. The ten-gene signature included: CKB (Creatine kinase B), CTNNBL1 (Catenin, beta like 1), GNG11 (G protein subunit gamma 11), IGFBP7 (Insulin-like growth factor-binding protein 7), PLCG2 (Phospholipase C, gamma 2), RNF24 (Ring finger protein 24), SLC15A3 (Solute carrier family 15 member 3), TSPAN31 (Tetraspanin 31), TTI1 (TELO2 interacting protein 1) and UQCC1 (Ubiquinol-cytochrome c reductase complex assembly factor). Cytotoxicity assays, combined with gene-expression analysis in primary HGSOC cell lines, allowed to define CTNNBL1, RNF24, and TTI1 as cell-autonomous contributors to tumor resistance.

CONCLUSIONS

Using machine-learning techniques we have identified a gene signature that could predict response to first-line chemotherapy in BRCAwt HGSOC patients, providing a useful tool towards personalized treatment modalities.

Partners in crime: The Lewis Y antigen and fucosyltransferase IV in Helicobacter pylori-induced gastric cancer

Helicobacter pylori (H. pylori) is a major causative agent of chronic gastritis, gastric ulcer and gastric carcinoma. H. pylori cytotoxin associated antigen A (CagA) plays a crucial role in the development of gastric cancer. Gastric cancer is associated with glycosylation alterations in glycoproteins and glycolipids on the cell surface. H. pylori cytotoxin associated antigen A (CagA) plays a significant role in the progression of gastric cancer through post-translation modification of fucosylation to develop gastric cancer. The involvement of a variety of sugar antigens in the progression and development of gastric cancer has been investigated, including type II blood group antigens. Lewis Y (LeY) is overexpressed on the tumor cell surface either as a glycoprotein or glycolipid. LeY is a difucosylated oligosaccharide, which is catalyzed by fucosyltransferases such as FUT4 (α1,3). FUT4/LeY overexpression may serve as potential correlative biomarkers for the prognosis of gastric cancer. We discuss the various aspects of H. pylori in relation to fucosyltransferases (FUT1-FUT9) and its fucosylated Lewis antigens (LeY, LeX, LeA, and LeB) and gastric cancer. In this review, we summarize the carcinogenic effect of H. pylori CagA in association with Le^Y and its synthesis enzyme FUT4 in the development of gastric cancer as well as discuss its importance in the prognosis and its inhibition by combination therapy of anti-Le^Y antibody and celecoxib through MAPK signaling pathway preventing gastric carcinogenesis.

The Interplay Between Non-coding RNAs and Insulin-Like Growth Factor Signaling in the Pathogenesis of Neoplasia

The insulin-like growth factors (IGFs) are polypeptides with similar sequences with insulin. These factors regulate cell growth, development, maturation, and aging via different processes including the interplay with MAPK, Akt, and PI3K. IGF signaling participates in the pathogenesis of neoplasia, insulin resistance, diabetes mellitus, polycystic ovarian syndrome, cerebral ischemic injury, fatty liver disease, and several other conditions. Recent investigations have demonstrated the interplay between non-coding RNAs and IGF signaling. This interplay has fundamental roles in the development of the mentioned disorders. We designed the current study to search the available data about the role of IGF-associated non-coding RNAs in the evolution of neoplasia and other conditions. As novel therapeutic strategies have been designed for modification of IGF signaling, identification of the impact of non-coding RNAs in this pathway is necessary for the prediction of response to these modalities.

Clinical study of serum IGFBP7 in predicting lymphatic metastasis in patients with lung adenocarcinoma

PURPOSE

To find serum tumor markers for predicting the presence of lymphatic metastasis in patients with lung adenocarcinoma, and to explore the diagnostic value of IGFBP7 in predicting if lymphatic metastasis occurs in lung adenocarcinoma.

METHODS

The concentration of IGFBP7 in the peripheral blood of 90 serum samples, including 30 patients with lung adenocarcinoma in situ, 30 patients with lung adenocarcinoma metastasis, and 30 normal controls were detected by ELISA. The data were analyzed statistically.

RESULTS

The concentration of IGFBP7 and D-dimer in the metastatic lung adenocarcinoma group was significantly higher than that in the lung adenocarcinoma in situ group (P < 0.05). The expression level of IGFBP7 in serum of patients with lung adenocarcinoma was associated with the clinical stage (P < 0.05) and lymphatic metastasis (P < 0.05). Using the receiver operating characteristic (ROC) curve, the area under the ROC curve of IGFBP7 was 0.901 (95% Confidence Interval was 0.806 to 0.996), and 0.5 was outside the 95% confidence interval (P < 0.05). The difference was statistically significant.

CONCLUSIONS

IGFBP7 can predict if the lung adenocarcinoma has lymphatic metastasis, which is helpful to improve the treatment of lung adenocarcinoma, and can be used as a new tumor marker to predict whether the lung adenocarcinoma has lymphatic metastasis or not.

Insulin Growth Factor Binding Protein 7 (IGFBP7)-Related Cancer and IGFBP3 and IGFBP7 Crosstalk

The insulin/insulin-like growth factors (IGFs) have crucial tasks in the growth, differentiation, and proliferation of healthy and pernicious cells. They are involved in coordinated complexes, including receptors, ligands, binding proteins, and proteases. However, the systems can become dysregulated in tumorigenesis. Insulin-like growth factor-binding protein 7 (IGFBP7) is a protein belonging to the IGFBP superfamily (also termed GFBP-related proteins). Numerous studies have provided evidence that IGFBP3 and IGFBP7 are involved in a variety of cancers, including hepatocellular carcinoma (HCC), breast cancer, gastroesophageal cancer, colon cancer, prostate cancer, among many others. Still, very few suggest an interaction between these two molecules. In studying several cancer types in our laboratories, we found that both proteins share some crucial signaling pathways. The objective of this review is to present a comprehensive overview of the relationship between IGFBP7 and cancer, as well as highlighting IGFBP3 crosstalk with IGFBP7 reported in recent studies.

IGFBP7 Induces Differentiation and Loss of Survival of Human Acute Myeloid Leukemia Stem Cells without Affecting Normal Hematopoiesis

Leukemic stem cells (LSCs) are thought to be the major cause of the recurrence of acute myeloid leukemia (AML) due to their potential for self-renewal. To identify therapeutic strategies targeting LSCs, while sparing healthy hematopoietic stem cells (HSCs), we performed gene expression profiling of LSCs, HSCs, and leukemic progenitors all residing within the same AML bone marrow and identified insulin-like growth factor-binding protein 7 (IGFBP7) as differentially expressed. Low IGFBP7 is a feature of LSCs and is associated with reduced chemotherapy sensitivity. Enhancing IGFBP7 by overexpression or addition of recombinant human IGFBP7 (rhIGFBP7) resulted in differentiation, inhibition of cell survival, and increased chemotherapy sensitivity of primary AML cells. Adding rhIGFBP7 reduced leukemic stem and/or progenitor survival and reversed a stem-like gene signature, but it had no influence on normal hematopoietic stem cell survival. Our data suggest a potential clinical utility of the addition of rhIGFBP7 to current chemotherapy regimens to decrease AML relapse rates.

Follistatin-like Protein 1 Inhibits Lung Cancer Metastasis by Preventing Proteolytic Activation of Osteopontin

Follistatin-like protein 1 (FSTL1) plays a critical role in lung organogenesis, but is downregulated during lung cancer development and progression. The prognostic significance and functional consequences of FSTL1 downregulation in lung cancer are unclear. Here, reduced levels of FSTL1 were detected in various tumors compared with normal tissues and were associated with poor clinical outcome in patients with non-small cell lung cancer, particularly those with lung adenocarcinoma. FSTL1 expression negatively correlated with the metastatic potential of lung cancer cells. Antibody-based neutralization of extracellular FSTL1 increased cellular migration/invasion while addition of recombinant FSTL1 protein diminished the metastatic capacity of lung cancer cells in vitro and in vivo. Notably, treatment with FSTL1 effectively prevented the metastatic progression of lung cancer cells in an orthotopic animal model. Mechanistically, FSTL1 directly bound to the proform of secreted phosphoprotein 1 (SPP1)/osteopontin, restraining proteolytic activation of SPP1, which led to inactivation of integrin/CD44-associated signaling and rearrangement of the actin cytoskeleton. Combined low expression of FSTL1 and high expression of SPP1 predicted a poorer prognosis for patients with lung cancer. This study highlights the novel interaction between FSTL1 and SPP1 and new opportunities to effectively target SPP1-driven metastatic cancers characterized by FSTL1 downregulation. SIGNIFICANCE: These findings describe the novel interaction between FSTL1 and SPP1 and its role in the metastatic progression of lung adenocarcinoma.

YAP-TEAD signaling promotes basal cell carcinoma development via a c-JUN/AP1 axis

The mammalian Hippo signaling pathway, through its effectors YAP and TAZ, coerces epithelial progenitor cell expansion for appropriate tissue development or regeneration upon damage. Its ability to drive rapid tissue growth explains why many oncogenic events frequently exploit this pathway to promote cancer phenotypes. Indeed, several tumor types including basal cell carcinoma (BCC) show genetic aberrations in the Hippo (or YAP/TAZ) regulators. Here, we uncover that while YAP is dispensable for homeostatic epidermal regeneration, it is required for BCC development. Our clonal analyses further demonstrate that the few emerging Yap-null dysplasia have lower fitness and thus are diminished as they progress to invasive BCC Mechanistically, YAP depletion in BCC tumors leads to effective impairment of the JNK-JUN signaling, a well-established tumor-driving cascade. Importantly, in this context, YAP does not influence canonical Wnt or Hedgehog signaling. Overall, we reveal Hippo signaling as an independent promoter of BCC pathogenesis and thereby a viable target for drug-resistant BCC.

Novel mutational landscapes and expression signatures of lung squamous cell carcinoma

Lung squamous cell carcinoma (LUSC) is a major subtype of Non-Small Cell Lung Cancer. To increase our understanding of the LUSC pathobiology, we performed exome sequencing and RNA-seq in 16 murine carcinogen-induced LUSC tumors and 8 normal murine lung tissue samples. Additionally, we conducted single-cell RNA-seq on two independent tumors from the same murine model. We identified a list of 59 cancer genes recurrently mutated in the mice LUSC tumors, 47 (80%) of which were also mutated in human LUSCs. At the single cell level, we detected unique clonal mutation patterns for each of the two LUSC tumors, being initiated from clones carrying the mutant Igfbp7 and Trp53 genes, respectively. We also identified an expression signature serving as an effective classifier for LUSC tumors and a strong predictor of survival outcomes of lung cancer patients. Lastly, we found that some of the mutant LUSC genes were associated with the significantly altered tumoral expression of inhibitory immune checkpoint genes such as PD-L1, VISTA, TIM3 and LAG3 in human LUSCs. The novel findings of clonal evolution, mutational landscapes and expression signatures of LUSC suggested new targets for the overall LUSC therapy and the immunotherapy of LUSC.

Low levels of IGFBP7 expression in high-grade serous ovarian carcinoma is associated with patient outcome

BACKGROUND

Insulin-like growth factor binding protein 7 (IGFBP7) has been suggested to act as a tumour suppressor gene in various human cancers, yet its role in epithelial ovarian cancer (EOC) has not yet been investigated. We previously observed that IGFBP7 was one of several genes found significantly upregulated in an EOC cell line model rendered non-tumourigenic as consequence of genetic manipulation. The aim of the present study was to investigate the role of IGFBP7 in high-grade serous ovarian carcinomas (HGSC), the most common type of EOC.

METHODS

We analysed IGFBP7 gene expression in 11 normal ovarian surface epithelial cells (NOSE), 79 high-grade serous ovarian carcinomas (HGSC), and seven EOC cell lines using a custom gene expression array platform. IGFBP7 mRNA expression profiles were also extracted from publicly available databases. Protein expression was assessed by immunohistochemistry of 175 HGSC and 10 normal fallopian tube samples using tissue microarray and related to disease outcome. We used EOC cells to investigate possible mechanisms of gene inactivation and describe various in vitro growth effects of exposing EOC cell lines to human recombinant IGFBP7 protein and conditioned media.

RESULTS

All HGSCs exhibited IGFBP7 expression levels that were significantly (p = 0.001) lower than the mean of the expression value of NOSE samples and that of a whole ovary sample. IGFBP7 gene and protein expression were lower in tumourigenic EOC cell lines relative to a non-tumourigenic EOC cell line. None of the EOC cell lines harboured a somatic mutation in IGFBP7, although loss of heterozygosity (LOH) of the IGFBP7 locus and epigenetic methylation silencing of the IGFBP7 promoter was observed in two of the cell lines exhibiting loss of gene/protein expression. In vitro functional assays revealed an alteration of the EOC cell migration capacity. Protein expression analysis of HGSC samples revealed that the large majority of tumour cores (72.6%) showed low or absence of IGFBP7 staining and revealed a significant correlation between IGFBP7 protein expression and a prolonged overall survival (p = 0.044).

CONCLUSION

The low levels of IGFPB7 in HGSC relative to normal tissues, and association with survival are consistent with a purported role in tumour suppressor pathways.

Insulin-like growth factor (IGF) signaling in tumorigenesis and the development of cancer drug resistance

One of the greatest obstacles to current cancer treatment efforts is the development of drug resistance by tumors. Despite recent advances in diagnostic practices and surgical interventions, many neoplasms demonstrate poor response to adjuvant or neoadjuvant radiation and chemotherapy. As a result, the prognosis for many patients afflicted with these aggressive cancers remains bleak. The insulin-like growth factor (IGF) signaling axis has been shown to play critical role in the development and progression of various tumors. Many basic science and translational studies have shown that IGF pathway modulators can have promising effects when used to treat various malignancies. There also exists a substantial body of recent evidence implicating IGF signaling dysregulation in the dwindling response of tumors to current standard-of-care therapy. By better understanding both the IGF-dependent and -independent mechanisms by which pathway members can influence drug sensitivity, we can eventually aim to use modulators of IGF signaling to augment the effects of current therapy. This review summarizes and synthesizes numerous recent investigations looking at the role of the IGF pathway in drug resistance. We offer a brief overview of IGF signaling and its general role in neoplasia, and then delve into detail about the many types of human cancer that have been shown to have IGF pathway involvement in resistance and/or sensitization to therapy. Ultimately, our hope is that such a compilation of evidence will compel investigators to carry out much needed studies looking at combination treatment with IGF signaling modulators to overcome current therapy resistance.

IGFBP7 induces apoptosis of acute myeloid leukemia cells and synergizes with chemotherapy in suppression of leukemia cell survival

Despite high remission rates after chemotherapy, only 30-40% of acute myeloid leukemia (AML) patients survive 5 years after diagnosis. This extremely poor prognosis of AML is mainly caused by treatment failure due to chemotherapy resistance. Chemotherapy resistance can be caused by various features including activation of alternative signaling pathways, evasion of cell death or activation of receptor tyrosine kinases such as the insulin growth factor-1 receptor (IGF-1R). Here we have studied the role of the insulin-like growth factor-binding protein-7 (IGFBP7), a tumor suppressor and part of the IGF-1R axis, in AML. We report that IGFBP7 sensitizes AML cells to chemotherapy-induced cell death. Moreover, overexpression of IGFBP7 as well as addition of recombinant human IGFBP7 is able to reduce the survival of AML cells by the induction of a G2 cell cycle arrest and apoptosis. This effect is mainly independent from IGF-1R activation, activated Akt and activated Erk. Importantly, AML patients with high IGFBP7 expression have a better outcome than patients with low IGFBP7 expression, indicating a positive role for IGFBP7 in treatment and outcome of AML. Together, this suggests that the combination of IGFBP7 and chemotherapy might potentially overcome conventional AML drug resistance and thus might improve AML patient survival.

Low expression of insulin-like growth factor binding protein 7 associated with poor prognosis in human glioma

OBJECTIVES

To investigate insulin-like growth factor binding protein 7 (IGFBP7) mRNA levels in human glioma and normal brain tissue, and to determine their clinical significance.

METHODS

In this retrospective study, IGFBP7 mRNA was quantified by real-time reverse transcription-polymerase chain reaction in brain tissue samples from patients with glioma and normal control subjects. Kaplan-Meier and Cox proportional hazards analyses were performed to determine any clinical and prognostic associations.

RESULTS

IGFBP7 mRNA levels were significantly lower in glioma tissue (n = 120) than in normal brain tissue (n = 20). Low (i.e. below the median, 5.9) IGFBP7 mRNA levels were significantly associated with larger tumour size (≥ 5 cm, compared with <5 cm, diameter). Patients with high (above median) IGFBP7 had longer overall survival than those with low IGFBP7. Tumour grade and IGFBP7 mRNA level were independent predictors of overall survival.

CONCLUSIONS

IGFBP7 downregulation is associated with poor prognosis in glioma, and this molecule may represent both a prognostic marker and a potential therapeutic target.

Insulin-like growth factor binding protein-related protein 1 contributes to hepatic fibrogenesis

OBJECTIVE

The aim of this study was to investigate the role of insulin-like growth factor binding protein-related protein 1 (IGFBP-rP1) in the development of hepatic fibrogenesis in experimental disease models and human liver samples.

METHODS

Cellular distribution patterns of IGFBP-rP1 were assessed by immunohistochemistry in fibrotic and cirrhotic human liver specimens. Gene silencing of IGFBP-rP1 was performed on cultured hepatic stellate cells (HSCs) by small interfering RNA (siRNA), and the silencing effect was determined by quantitative real-time polymerase chain reaction (PCR) and Western blot. We also determined the effects of siRNA-mediated gene silencing of IGFBP-rP1 on the production of extracellular matrix (ECM) components by Western blot. The expression of ECM components and transforming growth factor (TGF)-β1 was studied by immunohistochemistry and Western blot in C57BL/6 wild-type mice treated with recombinant IGFBP-rP1 (rIGFBP-rP1).

RESULTS

Expression of IGFBP-rP1 was significantly elevated in fibrotic and cirrhotic human liver specimens, and this increase was positively correlated with the number of collagen fibers observed. siRNA-mediated gene silencing of IGFBP-rP1 resulted in significantly decreased levels of collagen I and fibronectin in HSCs. Moreover, IGFBP-rP1 overexpression significantly increased the production of collagen, fibronectin and TGF-β1 in rIGFBP-rP1-treated mice.

CONCLUSIONS

IGFBP-rP1 contributes to the development of liver fibrosis and may be a novel molecule involved in the progression of hepatic fibrogenesis.

Insulin-like growth factor binding protein-related protein 1 and cancer

Insulin-like growth factor binding protein-related protein 1 (IGFBP-rP1) belongs to the IGFBP family whose members have a conserved structural homology. It has a low affinity for IGFs and a high affinity for insulin, suggesting that IGFBP-rP1 may have a biological function distinct from other members of the family. IGFBP-rP1 is ubiquitously expressed in normal human tissues and has diverse biological functions, regulating cell proliferation, apoptosis and senescence; it may also have a key role in vascular biology. Increasing evidence suggests that IGFBP-rP1 acts as a tumor suppressor. It elicits its biological effects by both insulin/IGF-dependent and -independent mechanisms. This paper provides a brief overview of the structure and regulation of IGFBP-rP1 and its various biological functions in cancer, as well as the underlying molecular mechanisms.

High expression of IGFBP7 in fibroblasts induced by colorectal cancer cells is co-regulated by TGF-β and Wnt signaling in a Smad2/3-Dvl2/3-dependent manner

Fibroblasts in the tumor microenvironment are a key determinant in cancer progression and may be a promising target for cancer therapy. Insulin-like growth factor binding protein 7 (IGFBP7) is known as a tumor suppressor in colorectal cancer (CRC). The present study investigated the inductive mechanism of IGFBP7 expression in fibroblasts by supernatant from the CRC cell line, SW620. The results showed that the expression of IGFBP7 was up-regulated in the fibroblasts when treated with SW620 supernatant and exogenous TGF-β1. The IGFBP7 induced by SW620 supernatant or TGF-β1 was partially inhibited by the TGF-β1 specific antibody AF and TGF-β1 receptor antagonist SB431542. The Wnt signaling-targeted genes, c-Myc, CCND1 and the proteins Dvl2/3, were all up-regulated in fibroblasts expressing high levels of IGFBP7, and the up-regulation could be inhibited both by the Wnt signaling antagonist Dickkopf-1 (DKK1) and by the TGF-β1 receptor antagonist SB431542. In conclusion, CRC cells promote the high expression of IGFBP7 in fibroblasts, most likely through the co-regulation of TGF-β and Wnt signaling in a Smad2/3-Dvl2/3 dependent manner. Taken together, these data suggest that the fibroblasts could be a novel therapeutic target in tumor therapy.