RON and MET Co-overexpression Are Significant Pathological Characteristics of Poor Survival and Therapeutic Targets of Tyrosine Kinase Inhibitors in Triple-Negative Breast Cancer

c-MET-positive circulating tumor cells and cell-free DNA as independent prognostic factors in hormone receptor-positive/HER2-negative metastatic breast cancer

BACKGROUND

Endocrine therapy resistance in hormone receptor-positive/HER2-negative (HR+/HER2-) breast cancer (BC) is a significant clinical challenge that poses several unmet needs in the management of the disease. This study aimed to investigate the prognostic value of c-MET-positive circulating tumor cells (cMET+ CTCs), ESR1/PIK3CA mutations, and cell-free DNA (cfDNA) concentrations in patients with hormone receptor-positive (HR+) metastatic breast cancer (mBC).

METHODS

Ninety-seven patients with HR+ mBC were prospectively enrolled during standard treatment at Samsung Medical Center. CTCs were isolated from blood using GenoCTC® and EpCAM or c-MET CTC isolation kits. PIK3CA and ESR1 hotspot mutations were analyzed using droplet digital PCR. CfDNA concentrations were calculated using internal control copies from the ESR1 mutation test. Immunocytochemistry was performed to compare c-MET overexpression between primary and metastatic sites.

RESULTS

The proportion of c-MET overexpression was significantly higher in metastatic sites than in primary sites (p = 0.00002). Survival analysis showed that c-MET+ CTC, cfDNA concentration, and ESR1 mutations were significantly associated with poor prognosis (p = 0.0026, 0.0021, and 0.0064, respectively) in HR+/HER2- mBC. By contrast, EpCAM-positive CTC (EpCAM+ CTC) and PIK3CA mutations were not associated with progression-free survival (PFS) in HR+/HER2- mBC. Multivariate analyses revealed that c-MET+ CTCs and cfDNA concentration were independent predictors of PFS in HR+/HER2- mBC.

CONCLUSIONS

Monitoring c-MET+ CTC, rather than assessing c-MET expression in the primary BC site, could provide valuable information for predicting disease progression, as c-MET expression can change during treatment. The c-MET+ CTC count and cfDNA concentration could provide complementary information on disease progression in HR+ /HER2- mBC, highlighting the importance of integrated liquid biopsy.

MET alterations detection platforms and clinical implications in solid tumors: a comprehensive review of literature

MET alterations, including MET exon 14 skipping variants, MET amplification, MET overexpression, and MET fusion, play pivotal roles in primary tumorigenesis and acquired resistance to targeted therapies, especially EGFR tyrosine kinase inhibitors. They represent important diagnostic, prognostic, and predictive biomarkers in many solid tumor types. However, the detection of MET alterations is challenging due to the complexity of MET alterations and the diversity of platform technologies. Therefore, techniques with high sensitivity, specificity, and reliable molecular detection accuracy are needed to overcome such hindrances and aid in biomarker-guided therapies. The current review emphasizes the role of MET alterations as oncogenic drivers in a variety of cancers and their involvement in the development of resistance to targeted therapies. Moreover, our review provides an overview of and recommendations on the selection of various cross-platform technologies for the detection of MET exon 14 skipping variants, MET amplification, MET overexpression, and MET fusion. Furthermore, challenges and hurdles underlying these common detection platforms are discussed.

Targeting Receptor Tyrosine Kinases as a Novel Strategy for the Treatment of Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) comprises a group of aggressive and heterogeneous breast carcinoma. Chemotherapy is the mainstay for the treatment of triple-negative tumors. Nevertheless, the success of chemotherapeutic treatments is limited by their toxicity and development of acquired resistance leading to therapeutic failure and tumor relapse. Hence, there is an urgent need to explore novel targeted therapies for TNBC. Receptor tyrosine kinases (RTKs) are a family of transmembrane receptors that are key regulators of intracellular signaling pathways controlling cell proliferation, differentiation, survival, and motility. Aberrant activity and/or expression of several types of RTKs have been strongly connected to tumorigenesis. RTKs are frequently overexpressed and/or deregulated in triple-negative breast tumors and are further associated with tumor progression and reduced survival in patients. Therefore, targeting RTKs could be an appealing therapeutic strategy for the treatment of TNBC. This review summarizes the current evidence regarding the antitumor activity of RTK inhibitors in preclinical models of TNBC. The review also provides insights into the clinical trials evaluating the use of RTK inhibitors for the treatment of patients with TNBC.

Defining the Emergence of New Immunotherapy Approaches in Breast Cancer: Role of Myeloid-Derived Suppressor Cells

Breast cancer (BC) continues to be the most diagnosed tumor in women and a very heterogeneous disease both inter- and intratumoral, mainly given by the variety of molecular profiles with different biological and clinical characteristics. Despite the advancements in early detection and therapeutic strategies, the survival rate is low in patients who develop metastatic disease. Therefore, it is mandatory to explore new approaches to achieve better responses. In this regard, immunotherapy arose as a promising alternative to conventional treatments due to its ability to modulate the immune system, which may play a dual role in this disease since the relationship between the immune system and BC cells depends on several factors: the tumor histology and size, as well as the involvement of lymph nodes, immune cells, and molecules that are part of the tumor microenvironment. Particularly, myeloid-derived suppressor cell (MDSC) expansion is one of the major immunosuppressive mechanisms used by breast tumors since it has been associated with worse clinical stage, metastatic burden, and poor efficacy of immunotherapies. This review focuses on the new immunotherapies in BC in the last five years. Additionally, the role of MDSC as a therapeutic target in breast cancer will be described.

The MST1R/RON Tyrosine Kinase in Cancer: Oncogenic Functions and Therapeutic Strategies

Simple Summary

MST1R/RON receptor tyrosine kinase is a highly conserved transmembrane protein present on epithelial cells, macrophages, and recently identified in a T-cell subset. RON activation attenuates inflammation in healthy tissue. Interestingly, it is overexpressed in several epithelial neoplasms with increasing levels of expression associated with worse outcomes. Though the mechanisms involved are still under investigation, RON is involved in carcinogenesis via immune modulation of the immune tumor microenvironment, activation of numerous oncogenic pathways, and is protective under cellular stress. Alternatively, inhibition of RON abrogates tumor progression in both animal and human tissue models. Given this, RON is a targetable protein of great interest for cancer treatment. Here, we review RON’s function in tissue inflammation and cancer progression, and review cancer clinical trials to date that have used agents targeting RON signaling.

Abstract

The MST1R/RON receptor tyrosine kinase is a homologue of the more well-known MET receptor. Like MET, RON orchestrates cell signaling pathways that promote oncogenesis and enable cancer cell survival; however, it has a more unique role in the regulation of inflammation. RON was originally described as a transmembrane receptor expressed on tissue resident macrophages and various epithelial cells. RON is overexpressed in a variety of cancers and its activation modifies multiple signaling pathways with resultant changes in epithelial and immune cells which together modulate oncogenic phenotypes. While several RON isoforms have been identified with differences in structure, activation, and pathway regulation, increased RON expression and/or activation is consistently associated with worse outcomes. Tyrosine kinase inhibitors targeting RON have been developed, making RON an actionable therapeutic target.

Antibody-Drug Conjugate PCMC1D3-Duocarmycin SA as a Novel Therapeutic Entity for Targeted Treatment of Cancers Aberrantly Expressing MET Receptor Tyrosine Kinase

BACKGROUND

Aberrant expression of the MET receptor tyrosine kinase is an oncogenic determinant and a drug target for cancer therapy. Currently, antibody-based biotherapeutics targeting MET are under clinical trials.

OBJECTIVE

Here we report the preclinical and therapeutic evaluation of a novel anti-MET antibody-drug conjugate PCMC1D3-duocarmycin SA (PCMC1D3-DCM) for targeted cancer therapy.

METHODS

The monoclonal antibody PCMC1D3 (IgG1a/κ), generated by a hybridoma technique and specific to one of the MET extracellular domains, was selected based on its high specificity to human MET with a binding affinity of 1.60 nM. PCMC1D3 was conjugated to DCM via a cleavable valine-citrulline dipeptide linker to form an antibody-drug conjugate with a drug-to-antibody ratio of 3.6:1. PCMC1D3-DCM in vitro rapidly induced MET internalization with an internalization efficacy ranging from 6.5 to 17.2h dependent on individual cell lines.

RESULTS

Studies using different types of cancer cell lines showed that PCMC1D3-DCM disrupted cell cycle, reduced cell viability, and caused massive cell death within 96h after treatment initiation. The calculated IC50 values for cell viability reduction were 1.5 to 15.3 nM. Results from mouse xenograft tumor models demonstrated that PCMC1D3-DCM in a single dose injection at 10 mg/kg body weight effectively delayed xenograft tumor growth up to two weeks without signs of tumor regrowth. The calculated tumoristatic concentration, a minimal dose required to balance tumor growth and inhibition, was around 2 mg/kg bodyweight. Taken together, PCMC1D3-DCM was effective in targeting inhibition of tumor growth in xenograft models.

CONCLUSION

This work provides the basis for the development of humanized PCMC1D3-DCM for MET-targeted cancer therapy in the future.

Drug Repositioning and Subgroup Discovery for Precision Medicine Implementation in Triple Negative Breast Cancer

Simple Summary

The heterogeneity of complicated diseases like cancer negatively affects patients’ responses to treatment. Finding homogeneous subgroups of patients within the cancer population and finding the appropriate treatment for each subgroup will improve patients’ survival. In this study, we focus on triple-negative breast cancer (TNBC), where approximately 80% of patients do not entirely respond to chemotherapy. Our aim is to find subgroups of TNBC patients and identify drugs that have the potential to tailor treatments for each group through drug repositioning. After applying our method to TNBC, we found that different targeted mechanisms were suggested for different groups of patients. Our findings could help the research community to gain a better understanding of different subgroups within the TNBC population and can help the drugs to be repurposed with explainable results regarding the targeted mechanism.

Abstract

Breast cancer (BC) is the leading cause of death among female patients with cancer. Patients with triple-negative breast cancer (TNBC) have the lowest survival rate. TNBC has substantial heterogeneity within the BC population. This study utilized our novel patient stratification and drug repositioning method to find subgroups of BC patients that share common genetic profiles and that may respond similarly to the recommended drugs. After further examination of the discovered patient subgroups, we identified five homogeneous druggable TNBC subgroups. A drug repositioning algorithm was then applied to find the drugs with a high potential for each subgroup. Most of the top drugs for these subgroups were chemotherapy used for various types of cancer, including BC. After analyzing the biological mechanisms targeted by these drugs, ferroptosis was the common cell death mechanism induced by the top drugs in the subgroups with neoplasm subdivision and race as clinical variables. In contrast, the antioxidative effect on cancer cells was the common targeted mechanism in the subgroup of patients with an age less than 50. Literature reviews were used to validate our findings, which could provide invaluable insights to streamline the drug repositioning process and could be further studied in a wet lab setting and in clinical trials.

RON Mediates Tumor-Promoting Effects in Endometrial Adenocarcinoma

Endometrial adenocarcinoma is one of the most prevalent female reproductive tract cancers in the world, and the development of effective treatment is still the main goal of its current research. Epithelial-mesenchymal transition (EMT) plays a significant part in the occurrence and development of epithelial carcinoma, including endometrial adenocarcinoma. Recepteur d'origine nantais (RON) induces EMT and promotes proliferation, migration, and invasion in various epithelial-derived cancers, but its role in endometrial adenocarcinoma is still poorly studied. The purpose of this study is to verify the overexpression of RON in endometrial adenocarcinoma and to explore its specific roles. RON expression in tumor lesions was verified by immunohistochemical staining, HEC-1B cells were used to construct stable cell lines with RON overexpression or knockdown to investigate the effects of RON on the function of endometrial adenocarcinoma cells, and xenotransplantation experiment was carried out in nude mice to explore the effect of RON on the growth of endometrial adenocarcinoma in vivo. This study revealed that RON could promote the proliferation, migration, and invasion of HEC-1B cells and induce EMT, and these effects were regulated through the Smad pathway. RON overexpression could promote growth of endometrial adenocarcinoma cells in nude mice, while its inhibitor BMS777607 could restrict this role. RON played an important role in endometrial adenocarcinoma and had a potential to become a new therapeutic target for endometrial adenocarcinoma.

MicroRNA Expression Profiling of Lung Cancer with Differential Expression of the RON Receptor Tyrosine Kinase

Background

The Ron receptor tyrosine kinase (RON) can act as a protooncogene and may play a prominent role in the initiation and development of lung cancer. microRNAs (miRNA) are master regulators of gene expression through direct or indirect regulation, and impact all aspects of cell biology.

Methods

Nonsmall-cell lung cancer (NSCLC) samples and small-cell lung cancer (SCLC) were stratified based on RON expression to identify miRNA profiles associated with RON expression levels, differentially expressed miRNA regulated by RON were screened out, and their biological behavior was analyzed.

Results

miRNA expression was most significantly affected by cancer type, and we found 85 miRNAs that were significantly differentially expressed between NSCLC and SCLC. There were 46 miRNAs differentially expressed between high RON expressing NSCLC compared to low RON expressing NSCLC. Biological processes and pathways found to be significantly influenced by RON expression included epithelial-mesenchymal transition (EMT) and activation of the PI3K-Akt and MAPK signaling pathways.

Conclusions

These data may provide the basis for a novel strategy to characterize lung cancer by RON expression and microRNA genotyping.

The MSP-RON pathway regulates liver fibrosis through transforming growth factor beta-dependent epithelial-mesenchymal transition

BACKGROUND

Liver fibrosis is pathologically important in the liver cirrhosis progression. The epithelial-mesenchymal transition (EMT) is crucial for organ fibrosis. Macrophage-stimulating protein (MSP) and its receptor tyrosine kinase, RON, promote cellular EMT. However, their role in liver fibrosis is unclear. Here, we clarify the biological profile, potential mechanisms and therapeutic targets of the MSP-RON pathway in liver fibrosis.

MATERIALS AND METHODS

Macrophage-stimulating protein expression and its correlation with clinicopathological characteristics of cirrhosis were evaluated in 57 clinical cases and a control group. The effect of MSP-RON pathway in liver fibrosis was determined in vitro and in vivo. The therapeutic effects of MSP or RON inhibition on liver fibrosis were evaluated in a mouse liver fibrosis model.

RESULTS

Macrophage-stimulating protein is upregulated in liver cirrhosis, which was associated with poor patient prognosis. The MSP-RON pathway promoted hepatocytes EMT. MSP-RON-induced EMT depends on the transforming growth factor beta (TGF-β) pathway and is regulated by TGF-β inhibitors. In animal models, an MSP blocking antibody and a small molecule inhibitor of RON, BMS-777607, both inhibited liver fibrosis progression.

CONCLUSION

Our study revealed that MSP is an important biomarker in liver cirrhosis progression and can be used to prognose patients. The MSP-RON pathway promotes the EMT of hepatocytes and the progress of fibrosis via a TGF-β related pathway. Consequently, we identified a new treatment strategy for liver cirrhosis through targeted inhibition of MSP/RON. This research increases the understanding of EMT-modulated liver fibrosis and provides new insights into biomarkers and therapeutic targets of liver fibrosis.

Small-Molecule Drug Discovery in Triple Negative Breast Cancer: Current Situation and Future Directions

Triple negative breast cancer (TNBC) is the most aggressive subtype of breast cancer, but an effective targeted therapy has not been well-established so far. Considering the lack of effective targets, where do we go next in the current TNBC drug development? A promising intervention for TNBC might lie in de novo small-molecule drugs that precisely target different molecular characteristics of TNBC. However, an ideal single-target drug discovery still faces a huge challenge. Alternatively, other new emerging strategies, such as dual-target drug, drug repurposing, and combination strategies, may provide new insight into the improvement of TNBC therapeutics. In this review, we focus on summarizing the current situation of a series of candidate small-molecule drugs in TNBC therapy, including single-target drugs, dual-target drugs, as well as drug repurposing and combination strategies that will together shed new light on the future directions targeting TNBC vulnerabilities with small-molecule drugs for future therapeutic purposes.

Pharmaceutical strategies in the emerging era of antibody-based biotherapeutics for the treatment of cancers overexpressing MET receptor tyrosine kinase

Pharmaceutical innovation in the development of novel antibody-based biotherapeutics with increased therapeutic indexes makes MET-targeted cancer therapy a clinical reality.

Clinical value and potential mechanisms of COL8A1 upregulation in breast cancer: a comprehensive analysis

Background

The situation faced by breast cancer patients, especially those with triple-negative breast cancer, is still grave. More effective therapeutic targets are needed to optimize the clinical management of breast cancer. Although collagen type VIII alpha 1 chain (COL8A1) has been shown to be downregulated in BRIP1-knockdown breast cancer cells, its clinical role in breast cancer remains unknown.

Methods

Gene microarrays and mRNA sequencing data were downloaded and integrated into larger matrices based on various platforms. Therefore, this is a multi-centered study, which contains 5048 breast cancer patients and 1161 controls. COL8A1 mRNA expression in breast cancer was compared between molecular subtypes. In-house immunohistochemistry staining was used to evaluate the protein expression of COL8A1 in breast cancer. A diagnostic test was performed to assess its clinical value. Furthermore, based on differentially expressed genes (DEGs) and co-expressed genes (CEGs) positively related to COL8A1, functional enrichment analyses were performed to explore the biological function and potential molecular mechanisms of COL8A1 underlying breast cancer.

Results

COL8A1 expression was higher in breast cancer patients than in control samples (standardized mean difference = 0.79; 95% confidence interval [CI] 0.55–1.03). Elevated expression was detected in various molecular subtypes of breast cancer. An area under a summary receiver operating characteristic curve of 0.80 (95% CI 0.76–0.83) with sensitivity of 0.77 (95% CI 0.69–0.83) and specificity of 0.70 (95% CI 0.61–0.78) showed moderate capacity of COL8A1 in distinguishing breast cancer patients from control samples. Worse overall survival was found in the higher than in the lower COL8A1 expression groups. Intersected DEGs and CEGs positively related to COL8A1 were significantly clustered in the proteoglycans in cancer and ECM-receptor interaction pathways.

Conclusions

Elevated COL8A1 may promote the migration of breast cancer by mediating the ECM-receptor interaction and synergistically interplaying with DEGs and its positively related CEGs independently of molecular subtypes. Several genes clustered in the proteoglycans in cancer pathway are potential targets for developing effective agents for triple-negative breast cancer.