Integrinβ1 modulates tumour resistance to gemcitabine and serves as an independent prognostic factor in pancreatic adenocarcinomas

Integrin β1 in Pancreatic Cancer: Expressions, Functions, and Clinical Implications

Simple Summary

Pancreatic cancer (PC) is a highly aggressive malignant tumor with an extremely poor prognosis. Early diagnosis and treatment are key to improving the survival rate of PC patients. Emerging studies show that integrins might contribute to the pathogenesis of PC. This review presents the various signaling pathways that are mediated by integrins in PC and emphasizes the multiple functions of integrin β1 in malignant behaviors of PC. It also discusses the clinical significance of integrin β1 as well as integrin β1-based therapy in PC patients.

Abstract

Pancreatic cancer (PC) is characterized by rapid progression and a high mortality rate. The current treatment is still based on surgical treatment, supplemented by radiotherapy and chemotherapy, and new methods of combining immune and molecular biological treatments are being explored. Despite this, the survival rate of PC patients is still very disappointing. Therefore, clarifying the molecular mechanism of PC pathogenesis and developing precisely targeted drugs are key to improving PC prognosis. As the most common β subunit of the integrin family, integrin β1 has been proved to be closely related to the vascular invasion, distant metastasis, and survival of PC patients, and treatment targeting integrin β1 in PC has gained initial success in animal models. In this review, we summarize the various signaling pathways by which integrins are involved in PC, focusing on the roles of integrin β1 in the malignant behaviors of PC. Additionally, recent studies regarding the feasibility of integrin β1 as a diagnostic and prognostic biomarker in PC are also discussed. Finally, we present the progress of several integrin β1-based clinical trials to highlight the potential of integrin β1 as a target for personalized therapy in PC.

Transcriptomic analysis reveals high ITGB1 expression as a predictor for poor prognosis of pancreatic cancer

Transcriptomic analysis of cancer samples helps identify the mechanism and molecular markers of cancer. However, transcriptomic analyses of pancreatic cancer from the Japanese population are lacking. Hence, in this study, we performed RNA sequencing of fresh and frozen pancreatic cancer tissues from 12 Japanese patients to identify genes critical for the clinical pathology of pancreatic cancer among the Japanese population. Additionally, we performed immunostaining of 107 pancreatic cancer samples to verify the results of RNA sequencing. Bioinformatics analysis of RNA sequencing data identified ITGB1 (Integrin beta 1) as an important gene for pancreatic cancer metastasis, progression, and prognosis. ITGB1 expression was verified using immunostaining. The results of RNA sequencing and immunostaining showed a significant correlation (r = 0.552, p = 0.118) in ITGB1 expression. Moreover, the ITGB1 high-expression group was associated with a significantly worse prognosis (p = 0.035) and recurrence rate (p = 0.028). We believe that ITGB1 may be used as a drug target for pancreatic cancer in the future.

Beta-blockers have no impact on survival in pancreatic ductal adenocarcinoma prior to cancer diagnosis

Previous studies have suggested that β-adrenergic signaling may regulate the growth of various cancers. The aim of our study is to investigate the association between the incidental use of beta-blockers for various conditions on the overall survival of patients with pancreatic ductal adenocarcinoma (PDAC). Patients with histologically-confirmed PDAC between 2007 and 2011 were extracted from Surveillance, Epidemiology, and End Results registry (SEER)-Medicare linked database. Kaplan Meier and multivariable Cox Proportional-Hazard models were used to examine the association between beta-blocker usage before diagnosis and overall survival adjusting for appropriate confounders. As an additional analysis we also examined continuous beta-blocker use before and after diagnosis. From 2007 to 2011, 13,731 patients were diagnosed with PDAC. Of these, 7130 patients had Medicare Part D coverage in the 6-month period before diagnosis, with 2564 (36%) of these patients using beta-blockers in this period. Patients receiving beta-blockers had a mean survival time of 5.1 months compared to 6 months for non-users (p < 0.01). In multivariable analysis, beta-blockers usage was not associated with improved survival (Hazard Ratio (HR) 1.04, 95%, Confidence Interval (CI) 0.98–1.1, p = 0.2). When patients were stratified by conditions with indications for beta-blocker usage, such as hypertension, coronary artery disease and cardiac arrhythmia, differences in survival were insignificant compared to non-users in all groups (p > 0.05). After stratification by receptor selectivity, this lack of association with survival persisted (p > 0.05 for all). As a subgroup analysis, looking at patients with continuous Medicare Part D coverage who used beta-blockers in the 6-month period before and after cancer diagnosis, we identified 7085 patients, of which 1750 (24.7%) had continuous beta blocker use. In multivariable analysis, continuous beta-blockers usage was associated with improved survival (Hazard Ratio (HR) 0.86, 95%, Confidence Interval (CI) 0.8–0.9, p < 0.01). Beta-blocker usage before diagnosis does not confer a survival advantage in patients with PDAC, though continuous use before and after diagnosis did confer a survival advantage. Prospective studies into the mechanism for this advantage are needed.

Emerging Kinase Therapeutic Targets in Pancreatic Ductal Adenocarcinoma and Pancreatic Cancer Desmoplasia

Kinase drug discovery represents an active area of therapeutic research, with previous pharmaceutical success improving patient outcomes across a wide variety of human diseases. In pancreatic ductal adenocarcinoma (PDAC), innovative pharmaceutical strategies such as kinase targeting have been unable to appreciably increase patient survival. This may be due, in part, to unchecked desmoplastic reactions to pancreatic tumors. Desmoplastic stroma enhances tumor development and progression while simultaneously restricting drug delivery to the tumor cells it protects. Emerging evidence indicates that many of the pathologic fibrotic processes directly or indirectly supporting desmoplasia may be driven by targetable protein tyrosine kinases such as Fyn-related kinase (FRK); B lymphoid kinase (BLK); hemopoietic cell kinase (HCK); ABL proto-oncogene 2 kinase (ABL2); discoidin domain receptor 1 kinase (DDR1); Lck/Yes-related novel kinase (LYN); ephrin receptor A8 kinase (EPHA8); FYN proto-oncogene kinase (FYN); lymphocyte cell-specific kinase (LCK); tec protein kinase (TEC). Herein, we review literature related to these kinases and posit signaling networks, mechanisms, and biochemical relationships by which this group may contribute to PDAC tumor growth and desmoplasia.

Role of Integrins in Resistance to Therapies Targeting Growth Factor Receptors in Cancer

Integrins contribute to cancer progression and aggressiveness by activating intracellular signal transduction pathways and transducing mechanical tension forces. Remarkably, these adhesion receptors share common signaling networks with receptor tyrosine kinases (RTKs) and support their oncogenic activity, thereby promoting cancer cell proliferation, survival and invasion. During the last decade, preclinical studies have revealed that integrins play an important role in resistance to therapies targeting RTKs and their downstream pathways. A remarkable feature of integrins is their wide-ranging interconnection with RTKs, which helps cancer cells to adapt and better survive therapeutic treatments. In this context, we should consider not only the integrins expressed in cancer cells but also those expressed in stromal cells, since these can mechanically increase the rigidity of the tumor microenvironment and confer resistance to treatment. This review presents some of these mechanisms and outlines new treatment options for improving the efficacy of therapies targeting RTK signaling.

Prognostic signature associated with radioresistance in head and neck cancer via transcriptomic and bioinformatic analyses

Background

Radiotherapy is an indispensable treatment modality in head and neck cancer (HNC), while radioresistance is the major cause of treatment failure. The aim of this study is to identify a prognostic molecular signature associated with radio-resistance in HNC for further clinical applications.

Methods

Affymetrix cDNA microarrays were used to globally survey different transcriptomes between HNC cell lines and isogenic radioresistant sublines. The KEGG and Partek bioinformatic analytical methods were used to assess functional pathways associated with radioresistance. The SurvExpress web tool was applied to study the clinical association between gene expression profiles and patient survival using The Cancer Genome Atlas (TCGA)-head and neck squamous cell carcinoma (HNSCC) dataset (n = 283). The Kaplan-Meier survival analyses were further validated after retrieving clinical data from the TCGA-HNSCC dataset (n = 502) via the Genomic Data Commons (GDC)-Data-Portal of National Cancer Institute. A panel maker molecule was generated to assess the efficacy of prognostic prediction for radiotherapy in HNC patients.

Results

In total, the expression of 255 molecules was found to be significantly altered in the radioresistant cell sublines, with 155 molecules up-regulated 100 down-regulated. Four core functional pathways were identified to enrich the up-regulated genes and were significantly associated with a worse prognosis in HNC patients, as the modulation of cellular focal adhesion, the PI3K-Akt signaling pathway, the HIF-1 signaling pathway, and the regulation of stem cell pluripotency. Total of 16 up-regulated genes in the 4 core pathways were defined, and 11 over-expressed molecules showed correlated with poor survival (TCGA-HNSCC dataset, n = 283). Among these, 4 molecules were independently validated as key molecules associated with poor survival in HNC patients receiving radiotherapy (TCGA-HNSCC dataset, n = 502), as IGF1R (p = 0.0454, HR = 1.43), LAMC2 (p = 0.0235, HR = 1.50), ITGB1 (p = 0.0336, HR = 1.46), and IL-6 (p = 0.0033, HR = 1.68). Furthermore, the combined use of these 4 markers product an excellent result to predict worse radiotherapeutic outcome in HNC (p < 0.0001, HR = 2.44).

Conclusions

Four core functional pathways and 4 key molecular markers significantly contributed to radioresistance in HNC. These molecular signatures may be used as a predictive biomarker panel, which can be further applied in personalized radiotherapy or as radio-sensitizing targets to treat refractory HNC.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-5243-3) contains supplementary material, which is available to authorized users.

Integrin β1 promotes gemcitabine resistance in pancreatic cancer through Cdc42 activation of PI3K p110β signaling

Pancreatic ductal adenocarcinoma (PDAC) is one of the most common malignancies with very poor prognosis due to its broad resistance to chemotherapy. Our previous study showed that integrin β1 expression is upregulated in PDAC and confers gemcitabine resistance in PDAC cells via the signaling pathway including Cdc42 and AKT activation. But the accurate signal transductions are not clear. Here, we aimed to illuminate the signal transductions of integrin β1 in the acquisition of gemcitabine resistance in PDAC. Drug-resistance (DR) cells from AsPC-1 parent cell line (PCL) were selected. Integrin β1 expression was determined using western blot assay. Changes in drug response and the activity of phosphatidylinositol 3-kinase (PI3K) signaling after knockdown of integrin β1, Cdc42 or p110β were evaluated using MTT, cleaved caspase-3 immunofluorescence and western blot assay. Western blot assays also detected the variations in Cdc42 activity and p110β expression after integrin β1 knockdown. The interaction between Cdc42 and p110β was determined by Glutathione S-transferase (GST) pull-down assay. The results showed that integrin β1 expression was upregulated in DR-AsPC-1 cells, and integrin β1 knockdown significantly decreased the activity of Cdc42, a target molecule of integrin β1, and p110β expression. Knockdown of anyone of integrin β1, Cdc42 and p110β inhibited the activity of PI3K signaling, and sensitized DR-AsPC-1 cells to gemcitabine. GST pull-down assay showed that GTP-Cdc42 interacted with p110β. Collectively, these data indicated that integrin β1 promoted gemcitabine resistance in PDAC through Cdc42 activation of PI3K p110β signaling. In vivo experiments also confirmed this conclusion. These findings contribute to a better understanding the molecular mechanism of chemoresistance and facilitate the development of more targeted and effective treatment strategy for PDAC.

Novel Methylselenoesters Induce Programed Cell Death via Entosis in Pancreatic Cancer Cells

Redox active selenium (Se) compounds have gained substantial attention in the last decade as potential cancer therapeutic agents. Several Se compounds have shown high selectivity and sensitivity against malignant cells. The cytotoxic effects are exerted by their biologically active metabolites, with methylselenol (CH₃SeH) being one of the key executors. In search of novel CH₃SeH precursors, we previously synthesized a series of methylselenoesters that were active (GI₅₀ < 10 µM at 72 h) against a panel of cancer cell lines. Herein, we refined the mechanism of action of the two lead compounds with the additional synthesis of new analogs (ethyl, pentyl, and benzyl derivatives). A novel mechanism for the programmed cell death mechanism for Se-compounds was identified. Both methylseleninic acid and the novel CH₃SeH precursors induced entosis by cell detachment through downregulation of cell division control protein 42 homolog (CDC42) and its downstream effector β1-integrin (CD29). To our knowledge, this is the first time that Se compounds have been reported to induce this type of cell death and is of importance in the characterization of the anticancerogenic properties of these compounds.

Prognostic value of increased integrin-beta 1 expression in solid cancers: a meta-analysis

Integrin-beta 1 (ITGB1) is aberrantly overexpressed or downregulated in solid cancers; however, its prognostic value remains controversial. Therefore, we conducted a meta-analysis to explore whether ITGB1 expression is correlated with overall survival (OS) and the clinicopathological characteristics of patients with solid cancers. We systematically searched the PubMed, Embase, and Web of Science databases for eligible studies published up to June 1, 2017. In total, 22 studies involving 3,666 patients were included. A sensitivity analysis was performed to assess the validity and reliability of the pooled OS. Among the 22 studies, 7 focused on lung cancer, 3 focused on colorectal cancer, 6 focused on breast cancer, 3 involved melanoma, and 3 involved pancreatic cancer. The pooled results showed that high ITGB1 expression was significantly associated with worse OS in lung cancer (pooled hazard ratio [HR]=1.78, 95% CI: 1.19–2.65, p<0.05) and breast cancer (pooled HR=1.88, 95% CI: 1.46–2.42, p<0.01). In addition, a significant association was observed between high ITGB1 expression and disease-free survival in breast cancer (pooled HR=1.63, 95% CI: 1.17–2.25, p<0.001) and pancreatic cancer (pooled HR=2.49, 95% CI: 1.35–4.61, p<0.001). However, high ITGB1 expression was not related to OS in colorectal cancer, pancreatic cancer, or melanoma. The pooled HRs used to evaluate the prognostic value of increased ITGB1 expression in lung cancer, breast cancer, and pancreatic cancer were not significantly altered, which indicates that the pooled results were robust. The results of this study indicate that the prognostic value of decreased ITGB1 expression varies among solid cancers.

Multi-omics analysis reveals that ornithine decarboxylase contributes to erlotinib resistance in pancreatic cancer cells

Molecular and metabolic alterations in cancer cells are one of the leading causes of acquired resistance to chemotherapeutics. In this study, we explored an experimental strategy to identify which of these alterations can induce erlotinib resistance in human pancreatic cancer. Using genetically matched erlotinib-sensitive (BxPC-3) and erlotinib-resistant (BxPC-3ER) pancreatic cancer cells, we conducted a multi-omics analysis of metabolomes and transcriptomes in these cells. Untargeted and targeted metabolomic analyses revealed significant changes in metabolic pathways involved in the regulation of polyamines, amino acids, and fatty acids. Further transcriptomic analysis identified that ornithine decarboxylase (ODC) and its major metabolite, putrescine, contribute to the acquisition of erlotinib resistance in BxPC-3ER cells. Notably, either pharmacological or genetic blockage of ODC was able to restore erlotinib sensitivity, and this could be rescued by treatment with exogenous putrescine in erlotinib-resistant BxPC-3ER cells. Moreover, using a panel of cancer cells we demonstrated that ODC expression levels in cancer cells are inversely correlated with sensitivity to chemotherapeutics. Taken together, our findings will begin to uncover mechanisms of acquired drug resistance and ultimately help to identify potential therapeutic markers in cancer.

SERP1 is a novel marker of poor prognosis in pancreatic ductal adenocarcinoma patients via anti-apoptosis and regulating SRPRB/NF-κB axis

Stress associated endoplasmic reticulum protein 1 (SERP1), can cause accumulation of unfolded proteins in ER stress. However, studies on the role of SERP1 in pancreatic ductal adenocarcinoma (PDAC) are still incomplete. The present study aimed at identifying whether SERP1 acts as a potential novel prognostic marker of PDAC, and analyzed its possible mechanism. GEO database analysis showed SERP1 was significantly upregulated in PDAC tissues, and strongly associated with advanced clinical stage of PDAC patients from TCGA database. Univariate and multivariate Cox regression analysis further revealed SERP1 high expression was an independent factor for the prognosis of PDAC. Gene set enrichment analysis (GSEA) revealed that SERP1 was mainly involved in regulating cell apoptosis and nuclear factor-κB (NF-κB) signaling pathway, and downregulated SERP1 significantly promoted PANC-1 cell apoptosis. To further explore its possible mechanism, protein-protein interaction (PPI) and gene ontology (GO) analysis showed the functions of proteins interacting with SERP1 were mainly enriched in regulating cell apoptosis, and SRP receptor β subunit (SRPRB) was the core of the whole PPI network. The expression of SERP1 was negatively correlated with SRPRB expression. In vitro, downregulated SERP1 significantly increased SRPRB expression. Furthermore, upregulated SRPRB could increase cell apoptosis rate and decreased the expression level of NF-κB and the phosphorylation NF-κB. The above results indicated that SERP1 as a potential novel prognostic marker of PDAC probably via regulating cell apoptosis and NF-κB activation, which may be associated with SRPRB.

The anti-tumor effects of the recombinant toxin protein rLj-RGD3 from Lampetra japonica on pancreatic carcinoma Panc-1 cells in nude mice

Recombinant Lampetra japonica RGD peptide (rLj-RGD3) is a soluble toxin protein with three RGD (Arg-Gly-Asp) motifs and a molecular weight of 13.5kDa. The aim of this study was to investigate the effects and mechanisms of rLj-RGD3 on tumor growth and survival in pancreatic carcinoma Panc-1 cell-bearing mice. A Panc-1 human pancreatic carcinoma-bearing nude mouse model was successfully generated, and the animals were treated with different doses of rLj-RGD3 for 3 weeks. The volume and weight of the subcutaneous tumors, the survival of the nude mice, histopathological changes, the intratumoral MVD, the number of apoptotic Panc-1 cells, and apoptosis-related proteins and gene expressions were determined. rLj-RGD3 significantly decreased the tumor volumes and weights, and the maximum tumor volume and weight IR values were 53.2% (p<0.001) and 55.9% (p<0.001), respectively. The life expectancy of Panc-1-bearing nude mice treated with rLj-RGD3 was increased by 56.3% (p<0.001). Meanwhile, rLj-RGD3 promoted the expression of Bax, caspase-3, and caspase-9 and inhibited Bcl-2 and VEGF expression. In addition, rLj-RGD3 did not change FAK, PI3K and Akt expression, but p-FAK, p-PI3K and p-Akt, levels were down-regulated. These results show that rLj-RGD3 induced potent anti-tumor activity in vivo and suppressed the growth of transplanted Panc-1 cells in a nude mouse model, implying that rLj-RGD3 may serve as a potent clinical therapeutic agent for human pancreatic carcinoma.

Reirradiation with stereotactic body radiation therapy after prior conventional fractionation radiation for locally recurrent pancreatic adenocarcinoma

Purpose

Locally recurrent pancreatic cancer after prior radiotherapy is a therapeutic challenge with limited treatment options. This study examines the safety and efficacy of stereotactic body radiation therapy (SBRT) for locally recurrent pancreatic adenocarcinoma after prior conventional fractionation radiotherapy (CRT).

Methods and materials

Outcomes from all patients treated with SBRT for locally recurrent pancreatic adenocarcinoma after prior CRT at our institution were reviewed. A total of 23 patients were identified. Prior CRT median dose was 50.4 Gy (range, 30-60 Gy). Twelve patients (52%) had previously undergone surgery and received CRT as neo- or adjuvant treatment. Nine patients (39.1%) were reirradiated with SBRT with a dose of 25 Gy in a single fraction, and 14 patients (60.8%) received a 5-fraction SBRT schedule with a median dose of 25 Gy (range, 20-33 Gy) in 5 fractions (1-5 fractions).

Results

Median follow-up time was 28 months (range, 9-77 months). The median planning target volume was 46 cm³ (range, 14-89 cm³). Median overall survival from diagnosis and from reirradiation were 27.5 months (range, 10-77 months) and 8.5 months (range, 1 month to not reached) respectively. The cumulative incidence of local failures at the last follow-up was 19%. For the 4 patients who presented with local failure, one was treated with a single fraction of 25 Gy, and the other 3 were treated with 25 Gy in 5 fractions. Three patients presented regional failure, with a cumulative incidence of 14%, all with concurrent distant progression. The cumulative incidence of distant progression was 64% at last follow-up. After reirradiation, 6 patients (26.1%) developed a grade 2 or 3 gastrointestinal toxicity, 4 of them occurring among patients treated with a single-fraction SBRT regimen.

Conclusions

Our report shows that SBRT for reirradiation of locally recurrent pancreas adenocarcinoma is a feasible option with good local control and acceptable toxicity rates, especially with a multifraction schedule.