Upregulation of EphB3 in gastric cancer with acquired resistance to a FGFR inhibitor

Targeting FGFR1 by β,β-dimethylacrylalkannin suppresses the proliferation of colorectal cancer in cellular and xenograft models

BACKGROUND

Colorectal cancer (CRC) continues to be a major global health challenge, ranking as a top cause of cancer-related mortality. Alarmingly, the five-year survival rate for CRC patients hovers around a mere 10-30 %. The disruption of fibroblast growth factor receptor (FGFRs) signaling pathways is significantly implicated in the onset and advancement of CRC, presenting a promising target for therapeutic intervention in CRC management. Further investigation is essential to comprehensively elucidate FGFR1's function in CRC and to create potent therapies that specifically target FGFR1.

PURPOSE

This study aims to demonstrate the oncogenic role of FGFR1 in colorectal cancer and to explore the potential of β,β-dimethylacrylalkannin (β,β-DMAA) as a therapeutic option to inhibit FGFR1.

METHODS

In this research, we employed a comprehensive suite of techniques including tissue array, kinase profiling, computational docking, knockdown assay to predict and explore the inhibitor of FGFR1. Furthermore, we utilized kinase assay, pull-down, cell proliferation tests, and Patient derived xenograft (PDX) mouse models to further investigate a novel FGFR1 inhibitor and its impact on the growth of CRC.

RESULTS

In our research, we discovered that FGFR1 protein is markedly upregulated in colorectal cancer tissues, suggesting a significant role in regulating cellular proliferation, particularly in patients with colorectal cancer. Furthermore, we conducted a computational docking, kinase profiling analysis, simulation and identified that β,β-DMAA could directly bind with FGFR1 within ATP binding pocket domain. Cell-based assays confirmed that β,β-DMAA effectively inhibited the proliferation of colon cancer cells and also triggered cell cycle arrest, apoptosis, and altered FGFR1-mediated signaling pathways. Moreover, β,β-DMAA effectively attenuated the development of PDX tumors in mice that were FGFR1-positive, with no notable toxicity observed. In summary, our study highlights the pivotal role of FGFR1 in colorectal cancer, suggesting that inhibiting FGFR1 activity could be a promising strategy for therapeutic intervention. We present strong evidence that targeting FGFR1 with β,β-DMAA is a viable approach for the management of colorectal cancer. Given its low toxicity and high efficacy, β,β-DMAA, as an FGFR1 inhibitor, warrants further investigation in clinical settings for the treatment of FGFR1-positive tumors.

Clinical Developments and Challenges in Treating FGFR2-Driven Gastric Cancer

Recent advances in the treatment of gastric cancer (GC) with chemotherapy, immunotherapy, anti-angiogenic therapy and targeted therapies have yielded some improvement in survival outcomes; however, metastatic GC remains a lethal malignancy and amongst the leading causes of cancer-related mortality worldwide. Importantly, the ongoing molecular characterisation of GCs continues to uncover potentially actionable molecular targets. Among these, aberrant FGFR2-driven signalling, predominantly arising from FGFR2 amplification, occurs in approximately 3-11% of GCs. However, whilst several inhibitors of FGFR have been clinically tested to-date, there are currently no approved FGFR-directed therapies for GC. In this review, we summarise the significance of FGFR2 as an actionable therapeutic target in GC, examine the recent pre-clinical and clinical data supporting the use of small-molecule inhibitors, antibody-based therapies, as well as novel approaches such as proteolysis-targeting chimeras (PROTACs) for targeting FGFR2 in these tumours, and discuss the ongoing challenges and opportunities associated with their clinical development.

Upregulation of Receptor Tyrosine Kinase Activity and Stemness as Resistance Mechanisms to Akt Inhibitors in Breast Cancer

The PI3K/Akt pathway is frequently deregulated in human cancers, and multiple Akt inhibitors are currently under clinical evaluation. Based on the experience from other molecular targeted therapies, however, it is likely that acquired resistance will be developed in patients treated with Akt inhibitors. We established breast cancer models of acquired resistance by prolonged treatment of cells with allosteric or ATP-competitive Akt inhibitors. Phospho-Receptor tyrosine kinase (Phospho-RTK) arrays revealed hyper-phosphorylation of multiple RTKS, including EGFR, Her2, HFGR, EhpB3 and ROR1, in Akt-inhibitor-resistant cells. Importantly, resistance can be overcome by treatment with an EGFR inhibitor. We further showed that cancer stem cells (CSCs) are enriched in breast tumor cells that have developed resistance to Akt inhibitors. Several candidates of CSC regulators, such as ID4, are identified by RNA sequencing. Cosmic analysis indicated that sensitivity of tumor cells to Akt inhibitors can be predicted by ID4 and stem cell/epithelial-mesenchymal transition pathway targets. These findings indicate the potential of targeting the EGFR pathway and CSC program to circumvent Akt inhibitor resistance in breast cancer.

Targeting FGFR2 Positive Gastroesophageal Cancer: Current and Clinical Developments

Despite recent advances in the systemic treatment of gastroesophageal cancers, prognosis remains poor. Comprehensive molecular analyses have characterized the genomic landscape of gastroesophageal cancer that has established therapeutic targets such as human epidermal growth factor receptor 2 (HER2), vascular endothelial growth factor receptor (VEGFR) and programmed death ligand 1 (PD-L1). The aberrant fibroblast growth factor receptor 2 (FGFR2) pathway is attractive for targetable therapy with FGFR inhibition based on preclinical data showing a pivotal role in the progression of gastric cancer (GC). FGFR2 amplification is the most common FGFR2 gene aberration in gastroesophageal cancer, and most associated with diffuse GC, which is often linked to poorer prognostic outcomes. There has been considerable progress with drug development focused on FGFR inhibition. At present, there is no approved FGFR inhibitor for FGFR2 positive gastroesophageal cancer. A selective FGFR2b monoclonal antibody bemarituzumab is currently being investigated in the first phase III randomized trial for patients with first line advanced GC, which may change the treatment paradigm for FGFR2b positive GC. The role of FGFR signalling, specifically FGFR2, is less established in oesophageal squamous cell cancer (ESCC) with a paucity of evidence for clinical benefit in these patients. Precision medicine is part of the wider approach in gastrointestinal cancers; however, it can be challenging due to heterogeneity and here circulating tumour DNA (ctDNA) for patient selection may have future clinical utility. In our review, we outline the FGFR pathway and focus on the developments and challenges of targeting FGFR2 driven gastroesophageal cancers.

Pemigatinib for adults with previously treated, locally advanced or metastatic cholangiocarcinoma with FGFR2 fusions/rearrangements

Biliary tract cancers are a diverse and aggressive malignancy that carry a poor chance for curative treatment and significant associated mortality. Current first-line treatment only extends median overall survival to roughly 1 year and is associated with a significant adverse event profile. Recently, advancements in genetic sequencing have opened new avenues of targeted treatment. In cholangiocarcinoma, FGFR2 alterations have been shown to be present in roughly 10-15% of intrahepatic cholangiocarcinoma. Pemigatinib, a FGFR1-4 inhibitor, has been shown to significantly extend survival in the second-line setting to over 20 months in patients who harbor FGFR2 fusions. Here, we outline the development and future direction of pemigatinib and other FGFR2 inhibitors in the field of advanced biliary tract cancers.

Exosomal circRELL1 serves as a miR-637 sponge to modulate gastric cancer progression via regulating autophagy activation

Circular RNAs (circRNAs) play a vital role in the occurrence and development of tumors, including gastric cancer (GC). However, there are still many circRNAs related to GC whose functions and molecular mechanisms remain undetermined. Herein, we discover circRNA RELL1, which has not been investigated in GC, and it is markedly downregulated in GC tissues, which is related with poor prognosis, more pronounced lymph node metastasis and poor TNM stage. After confirming the circular structure of circRELL1, we found that circRELL1 could block cell proliferation, invasion, migration, and anti-apoptosis in patients with GC by a series of in vivo and in vitro function-related studies. Further mechanism investigation demonstrated that circRELL1 could sponge miR-637 and indirectly unregulated the expression of EPHB3 via modulating autophagy activation in GC. Additionally, circRELL1 can be transmitted by exosomal communication, and exosomal circRELL1 suppressed the malignant behavior of GC in vivo and in vitro. Taken together, this study elucidates the suppressive roles of circRELL1/miR-637/EPHB3 axis through autophagy activation in GC progression, inspiring for further understanding of the underlying molecular mechanisms of GC and providing a promising novel diagnostic circulating biomarker and therapeutic target in GC.

Hit Identification of a Novel Quinazoline Sulfonamide as a Promising EphB3 Inhibitor: Design, Virtual Combinatorial Library, Synthesis, Biological Evaluation, and Docking Simulation Studies

EphB3 is a major key player in a variety of cellular activities, including cell migration, proliferation, and apoptosis. However, the exact role of EphB3 in cancer remains ambiguous. Accordingly, new EphB3 inhibitors can increase the understanding of the exact roles of the receptor and may act as promising therapeutic candidates. Herein, a hybrid approach of structure-based design and virtual combinatorial library generated 34 quinazoline sulfonamides as potential selective EphB3 inhibitors. A molecular docking study over EphB3 predicted the binding affinities of the generated library, and the top seven hit compounds (3a and 4a–f), with GlideScore ≥ −6.20 Kcal/mol, were chosen for further MM-GBSA calculations. Out of the seven top hits, compound 4c showed the highest MM-GBSA binding free energy (−74.13 Kcal/mol). To validate these predicted results, compounds 3a and 4a–f were synthesized and characterized using NMR, HRMS, and HPLC. The biological evaluation revealed compound 4c as a potent EphB3 inhibitory lead (IC₅₀ = 1.04 µM). The screening of 4c over a mini-panel of kinases consisting of EGFR, Aurora A, Aurora B, CDK2/cyclin A, EphB1, EphB2, EphB4, ERBB2/HER2, and KDR/VEGFR2, showed a promising selective profile against EphB3 isoform. A dose-dependent assay of compound 4c and a molecular docking study over the different forms of EphB provided insights into the elicited biological activities and highlighted reasonable explanations of the selectivity.

Comprehensive characterization of pathological stage-related genes of papillary thyroid cancer along with survival prediction

It is crucial to understand the differences across papillary thyroid cancer (PTC) stages, so as to provide a basis for individualized treatments. Here, comprehensive function characterization of PTC stage‐related genes was performed and a new prognostic signature was developed for advanced patients. Two gene modules were confirmed to be closely associated with PTC stages and further six hub genes were identified that yield excellent diagnostic efficiency between tumour and normal tissues. Genetic alteration analysis indicates that they are much conservative since mutations in the DNA of them rarely occur, but changes of DNA methylation on these six genes show that 12 DNA methylation sites are significantly associated with their corresponding genes' expression. Validation data set testing also suggests that these six stage‐related hub genes would be probably potential biomarkers for marking four stages. Subsequently, a 21‐mRNA‐based prognostic risk model was constructed for PTC stage III/IV patients and it could effectively predict the survival of patients with strong prognostic ability. Functional analysis shows that differential expression genes between high‐ and low‐risk patients would promote the progress of PTC to some extent. Moreover, tumour microenvironment (TME) of high‐risk patients may be more conducive to tumour growth by ESTIMATE analysis.

FGFR-TKI resistance in cancer: current status and perspectives

Fibroblast growth factor receptors (FGFRs) play key roles in promoting the proliferation, differentiation, and migration of cancer cell. Inactivation of FGFRs by tyrosine kinase inhibitors (TKI) has achieved great success in tumor-targeted therapy. However, resistance to FGFR-TKI has become a concern. Here, we review the mechanisms of FGFR-TKI resistance in cancer, including gatekeeper mutations, alternative signaling pathway activation, lysosome-mediated TKI sequestration, and gene fusion. In addition, we summarize strategies to overcome resistance, including developing covalent inhibitors, developing dual-target inhibitors, adopting combination therapy, and targeting lysosomes, which will facilitate the transition to precision medicine and individualized treatment.

Pemigatinib, a potent inhibitor of FGFRs for the treatment of cholangiocarcinoma

The prognosis of patients affected by cholangiocarcinoma is classically poor. Until recently, chemotherapeutic drugs were the only systemic treatment option available, leading to an overall survival lower than 1 year. In recent decades, different genetic alterations have been identified as playing a key role in the oncogenic signaling. A subgroup of intrahepatic cholangiocarcinoma is characterized by FGFR family mutations, more frequently represented by gene fusions of FGFR2. Based on the results of FIGHT-202 trial, in April 2020 the US FDA approved the FGFR inhibitor pemigatinib in advanced previously treated cholangiocarcinoma patients with FGFR2 rearrangements, opening the way to targeted therapy in this disease. This review summarizes the body of evidence about the efficacy of pemigatinib in cholangiocarcinoma.

The Key microRNAs Regulated the Development of Non-small Cell Lung Cancer by Targeting TGF-β-induced epithelial-mesenchymal Transition

PURPOSE

Epithelial-to-Mesenchymal Transition (EMT) was reported to play a key role in the development of Non-Small Cell Lung Cancer (NSCLC). The process of EMT is regulated by the changes of miRNAs expression. However, it is still unknown which miRNA changed the most in the process of canceration and whether these changes played a role in tumor development.

METHODS

A total of 36 SCLC patients treated in our hospital between 11th, 2015 and 10th, 2017 were enrolled. The samples of cancer tissues and paracancer tissues of patients were collected and analyzed. Then, the miRNAs in normal lung cells and NSCLC cells were also analyzed. In the presence of TGF-β, we transfected the miRNA mimics or inhibitor into NSCLC cells to investigate the role of the significantly altered miRNAs in cell migration and invasion and in the process of EMT.

RESULTS

MiR-330-3p was significantly up-regulated in NSCLC cell lines and tissues and miRNA- 205 was significantly down-regulated in NSCLC cell lines and NSCLC tissues. Transfected miRNA-205 mimics or miRMA-330-3p inhibitor inhibited the migration and invasion of NCIH1975 cell and restrained TGF-β-induced EMT in NSCLC cells.

CONCLUSION

miRNA-330-3p and miRNA-205 changed the most in the process of canceration in NSCLC. Furthermore, miR-330-3p promoted cell invasion and metastasis in NSCLC probably by promoting EMT and miR-205 could restrain NSCLC likely by suppressing EMT.

Prognostic and Clinicopathological Significance of EphB3 and Dysadherin Expression in Extrahepatic Cholangiocarcinoma

Aim

EphB3 and dysadherin are involved in tumorigenesis and progression of many neoplasms. However, the roles of EphB3 and dysadherin in extrahepatic cholangiocarcinoma (ECC) remain to be revealed. In this study, we aimed to evaluate the expression of EphB3 and dysadherin, and investigate their clinicopathological significance in ECC.

Methods

We examined EphB3 and dysadherin expression in 100 ECC, 30 peritumoral tissues, 10 adenoma and 15 normal biliary tract tissues using EnVision immunohistochemistry. The relationship between EphB3 or dysadherin expression and clinicopathological features was evaluated using the χ² test or Fisher’s exact test. The overall survival of ECC patients was analyzed using Kaplan-Meier univariate survival analysis and Log rank tests.

Results

We found that EphB3 expression was significantly down-regulated and dysadherin expression was significantly up-regulated in ECC tissues compared with normal tissues (P < 0.01). EphB3 expression was negatively correlated with dysadherin expression in ECC (P < 0.01). The positive rate of EphB3 expression and negative rate of dysadherin expression was significantly higher in patients with well-differentiated type, no lymph node metastasis, no surrounding tissues and organs invasion, early TNM stages (I + II) and radical resection (P < 0.01). The survival of ECC patients with positive EphB3 or negative dysadherin expression was significantly longer than patients with negative EphB3 or positive dysadherin expression (P < 0.01). Cox multivariate analysis demonstrated that negative EphB3 or positive dysadherin expression were independent poor prognostic factors in ECC patients. The ROC curves suggested that EphB3 and dysadherin combined diagnostic efficacy (AUC=0.688, 95%CI: 0.603-0.772) was significantly higher EphB3 diagnostic efficacy (AUC=0.654, 95%CI: 0.564-0.743) or dysadherin diagnostic efficacy (AUC=0.648, 95%CI: 0.558-0.737) alone.

Conclusion

EphB3 and dysadherin are involved in the carcinogenesis and progression of ECC, and ECC patients with negative EphB3 or positive dysadherin expression have a poor prognosis.

Knockdown Of CCDC132 Attenuates Gastric Cancer Cells Proliferation And Tumorigenesis By Facilitating DNA Damage Signaling

Background

Aberrant endocytic recycling has fundamental functions on plasma membrane component turnover. Recent studies have identified an uncharacterized protein, CCDC132, in the endosome-associated recycling protein complex. Besides, our preliminary data first showed that CCDC132 was elevated in malignant neoplasms, especially in esophagus/stomach cancers. However, the functions and the underlying mechanisms of CCDC132 in gastric cancer (GC) biology remain unclear.

Methods

The CCDC132 mRNA expression in 4 GC cell lines and normal gastric epithelial cell lines was detected by qRT-PCR. Then, CCDC132 was downregulated in AGS and MGC-803 cells by lentivirus-induced RNA interfere, and cell viability assay, clone formation assay and apoptosis assay were carried out. The mechanism of CCDC132 on cell proliferation and apoptosis activation was explored using PathScan^® Stress, apoptosis signaling arrays and Western blot. We further investigated the pro-oncogenesis of CCDC132 in vivo. Meanwhile, immunohistochemistry was utilized to analyze the association between CCDC132 expression and clinicopathological features and prognosis. Finally, the correlation between CCDC132 and p53 was analyzed by Spearman’s rank correlation analysis.

Results

In this study, knockdown of CCDC132 significantly decreased cell proliferation and clone formation ability and facilitated apoptosis, and increased phosphorylation of p53 and Chk2 and protein levels of γ-H2AX, 53BP1, cleaved Caspase 3 and cleaved PARP. Additionally, knockdown of CCDC132 attenuated tumorigenesis and tumor growth of MGC-803 cell xenografts. CCDC132 expression was significantly higher in GC tissues compared with that in adjacent normal tissues and was positively correlated with nodal metastasis and TNM stage and negatively associated with prognosis. The survival rate of CCDC132 positive patients was lower than that of CCDC132-negative patients. Furthermore, CCDC132 expression was negatively related to p53.

Conclusion

This study unravels that knockdown of CCDC132 attenuates GC cell proliferation and tumorigenesis by facilitating DNA damage signaling, indicating that CCDC132 may serve as a potential target for GC therapy.

Mechanisms of acquired resistance to fibroblast growth factor receptor targeted therapy

Oncogenic activation of the fibroblast growth factor receptor (FGFR) through mutations and fusions of the FGFR gene occur in a variety of different malignancies such as urothelial carcinoma and cholangiocarcinoma. Inhibition of the kinase domain of the FGFR with targeted oral FGFR inhibitors has been shown in both preclinical and early phase clinical trials to lead to meaningful reductions in tumour size and larger confirmatory randomized trials are underway. Acquired resistance to FGFR inhibition using a variety of mechanisms that includes, activation of alternate signaling pathways and expansion of tumour clones with gatekeeper mutations in the FGFR gene. This review summarizes the acquired resistance mechanisms to FGFR therapy and therapeutic approaches to circumventing resistance.

FGFR2-Altered Gastroesophageal Adenocarcinomas Are an Uncommon Clinicopathologic Entity with a Distinct Genomic Landscape

Little is known about the genomic landscape of FGFR2‐altered gastroesophageal adenocarcinomas. This article attempts to bridge that gap, with a focus on concurrent alterations that may affect sensitivity to FGFR2‐directed therapies.

Background.

With the exception of trastuzumab, therapies directed at receptor tyrosine kinases (RTKs) in gastroesophageal adenocarcinomas (GEA) have had limited success. Recurrent fibroblast growth factor receptor 2 (FGFR2) alterations exist in GEA; however, little is known about the genomic landscape of FGFR2‐altered GEA. We examined FGFR2 alteration frequency and frequency of co‐occurring alterations in GEA.

Subjects, Materials, and Methods.

A total of 6,667 tissue specimens from patients with advanced GEA were assayed using hybrid capture‐based genomic profiling. Tumor mutational burden (TMB) was determined on up to 1.1 Mb of sequenced DNA, and microsatellite instability was determined on 95 or 114 loci. Descriptive statistics were used to compare subgroups.

Results.

We identified a total of 269 (4.0%) FGFR2‐altered cases consisting of FGFR2‐amplified (amp; 193, 72% of FGFR2‐altered), FGFR2‐mutated (36, 13%), FGFR2‐rearranged (re; 23, 8.6%), and cases with multiple FGFR2 alterations (17, 6.3%). Co‐occurring alterations in other GEA RTK targets including ERBB2 (10%), EGFR (8%), and MET (3%) were observed across all classes of FGFR2‐altered GEA. Co‐occurring alterations in MYC (17%), KRAS (10%), and PIK3CA (5.6%) were also observed frequently. Cases with FGFR2amp and FGFR2re were exclusively microsatellite stable. The median TMB for FGFR2‐altered GEA was 3.6 mut/mb, not significantly different from a median of 4.3 mut/mb seen in FGFR2 wild‐type samples.

Conclusion.

FGFR2‐altered GEA is a heterogenous subgroup with approximately 20% of FGFR2‐altered samples harboring concurrent RTK alterations. Putative co‐occurring modifiers of FGFR2‐directed therapy including oncogenic MYC, KRAS, and PIK3CA alterations were also frequent, suggesting that pretreatment molecular analyses may be needed to facilitate rational combination therapies and optimize patient selection for clinical trials.

Implications for Practice.

Actionable receptor tyrosine kinase alterations assayed within a genomic context with therapeutic implications remain limited to HER2 amplification in gastroesophageal adenocarcinomas (GEA). Composite biomarkers and heterogeneity assessment are critical in optimizing patients selected for targeted therapies in GEA. Comprehensive genomic profiling in FGFR2‐altered GEA parallels the heterogeneity findings in HER2‐amplified GEA and adds support to the utility of genomic profiling in advanced gastroesophageal adenocarcinomas.

BRAFV600E-mutant cancers display a variety of networks by SWIM analysis: prediction of vemurafenib clinical response

PURPOSE

Several studies have shown that different tumour types sharing a driver gene mutation do not respond uniformly to the same targeted agent. Our aim was to use an unbiased network-based approach to investigate this fundamental issue using BRAF^V600E mutant tumours and the BRAF inhibitor vemurafenib.

METHODS

We applied SWIM, a software able to identify putative regulatory (switch) genes involved in drastic changes to the cell phenotype, to gene expression profiles of different BRAF^V600E mutant cancers and their normal counterparts in order to identify the switch genes that could potentially explain the heterogeneity of these tumours' responses to vemurafenib.

RESULTS

We identified lung adenocarcinoma as the tumour with the highest number of switch genes (298) compared to its normal counterpart. By looking for switch genes encoding for kinases with homology sequences similar to known vemurafenib targets, we found that thyroid cancer and lung adenocarcinoma have a similar number of putative targetable switch gene kinases (5 and 6, respectively) whereas colorectal cancer has just one.

CONCLUSIONS

We are persuaded that our network analysis may aid in the comprehension of molecular mechanisms underlying the different responses to vemurafenib in BRAF^V600E mutant tumours.

Sonic hedgehog pathway activation is associated with cetuximab resistance and EPHB3 receptor induction in colorectal cancer

A major problem of colorectal cancer (CRC) targeted therapies is relapse caused by drug resistance. In most cases of CRC, patients develop resistance to anticancer drugs. Cetuximab does not show many of the side effects of other anticancer drugs and improves the survival of patients with metastatic CRC. However, the molecular mechanism of cetuximab resistance is not fully understood.

Methods: EPHB3-mediated cetuximab resistance was confirmed by in vitro western blotting, colony-forming assays, WST-1 colorimetric assay, and in vivo xenograft models (n = 7 per group). RNA-seq analysis and receptor tyrosine kinase assays were performed to identify the cetuximab resistance mechanism of EPHB3. All statistical tests were two-sided.

Results: The expression of EFNB3, which upregulates the EPHB3 receptor, was shown to be increased via microarray analysis. When resistance to cetuximab was acquired, EPHB3 protein levels increased. Hedgehog signaling, cancer stemness, and epithelial-mesenchymal transition signaling proteins were also increased in the cetuximab-resistant human colon cancer cell line SW48R. Despite cells acquiring resistance to cetuximab, STAT3 was still responsive to EGF and cetuximab treatment. Moreover, inhibition of EPHB3 was associated with decreased STAT3 activity. Co-immunoprecipitation confirmed that EGFR and EPHB3 bind to each other and this binding increases upon resistance acquisition, suggesting that STAT3 is activated by the binding between EGFR and EPHB3. Protein levels of GLI-1, SOX2, and Vimentin, which are affected by STAT3, also increased. Similar results were obtained in samples from patients with CRC.

Conclusion: EPHB3 expression is associated with anticancer drug resistance.

Effects of VEGFR1+ hematopoietic progenitor cells on pre-metastatic niche formation and in vivo metastasis of breast cancer cells

The pre-metastatic niche has been shown to play a critical role in tumor metastasis, and its formation is closely related to the tumor microenvironment. However, the underlying molecular mechanisms remain unclear. In the present study, we successfully established a mouse model of lung metastasis using luciferase-expressing MDA-MB-435s cells. In this model, recruitment of vascular endothelial growth factor receptor-1 (VEGFR1)⁺CD133⁺ hematopoietic progenitor cells (HPCs) was gradually increased in lung but gradually decreased after the formation of tumor colonies in lung. We also established a highly metastatic MDA-MB-435s (MDA-MB-435s-HM) cell line from the mouse model. Changes in protein profiles in different culture conditions were investigated by protein microarray analysis. The levels of CXC chemokine ligand 16, interleukin (IL)-2Rα, IL-2Rγ, matrix metalloproteinase (MMP)-1, MMP-9, platelet-derived growth factor receptor (PDGFR)-α, stromal cell-derived factor (SDF)-1α, transforming growth factor (TGF)-β, platelet endothelial cell adhesion molecule (PECAM)-1 and vascular endothelial (VE)-cadherin were significantly greater (> fivefold) in the culture medium from MDA-MB-435s-HM cells than in that from MDA-MB-435s cells. Moreover, the levels of MMP-9, PDGFR-α, and PECAM-1 were significantly greater in the co-culture medium of MDA-MB-435s-HM cells and CD133⁺ HPCs than in that from MDA-MB-435s-HM cells. Differentially expressed proteins were validated by enzyme-linked immunosorbent assay, and expression of their transcripts was confirmed by quantitative real-time polymerase chain reaction. Moreover, inhibition of MMP-9, PDGFR-α, and PECAM-1 by their specific inhibitors or antibodies significantly decreased cell migration, delayed lung metastasis, and decreased recruitment of VEGFR1⁺CD133⁺ HPCs into lung. Intra-hepatic growth of HPCs enhanced the invasive growth of MDA-MB-435s-HM cells in the liver. Our data indicate that VEGFR1⁺CD133⁺ HPCs contribute to lung metastasis.

MicroRNA-645 targets urokinase plasminogen activator and decreases the invasive growth of MDA-MB-231 triple-negative breast cancer cells

Background

Urokinase plasminogen activator (uPA) promotes the in vivo invasive growth of HCC cells by cleaving and activating matrix metalloproteinases (MMPs) to induce the destruction of the extracellular matrix of triple-negative breast cancer (TNBC) cells. The identification of microRNAs that target uPA and decrease uPA expression would be useful for attenuating the in vivo invasive growth of TNBC cells.

Materials and methods

MicroRNA-645 (miR-645) was identified using an online tool (miRDB) as potentially targeting uPA; miR-645 inhibition of uPA was confirmed by western blot experiments. The effects of miR-645 on the in vivo invasive growth of TNBC cells were examined using an intrahepatic tumor model in nude mice, and the miR-645 mechanism of action was explored with MMP cleaving experiments.

Results

Through virtual screening, we discovered that miR-645 potentially targeted the uPA 3′ untranslated region. This targeting was confirmed by western blot experiments and miR-645 lentiviral particle (LV-645) transduction that inhibited uPA expression in MDA-MB-231 TNBC cells. The LV-645 inhibition of uPA led to the decreased invasive growth of TNBC cells in nude mice. The mechanism data indicated that the uPA inhibition resulted in a decreased cleaving of the pro-MMP-9 protein.

Conclusion

Targeting uPA with miR-645 decreased the in vivo invasive growth of TNBC cells. These results suggest that miR-645 may represent a promising treatment strategy for TNBC.