Met in urological cancers

c-Met: A Promising Therapeutic Target in Bladder Cancer

Mesenchymal-epithelial transition factor (c-Met) belongs to the tyrosine kinase receptor family and is overexpressed in various human cancers. Its ligand is hepatocyte growth factor (HGF), and the HGF/c-Met signaling pathway is involved in a wide range of cellular processes, including cell proliferation, migration, and metastasis. Emerging studies have indicated that c-Met expression is strongly associated with bladder cancer (BCa) development and prognosis. Therefore, c-Met is a potential therapeutic target for BCa treatment. Recently, the aberrant expression of noncoding RNAs was found to play a significant role in tumour progression. There is a close connection between c-Met and noncoding RNA. Herein, we summarized the biological function and prognostic value of c-Met in BCa, as well as its potential role as a drug target. The relation of c-Met and ncRNA was also described in the paper.

SOX8 promotes cetuximab resistance via HGF/MET bypass pathway activation in colorectal cancer

AIM

Cetuximab is an essential drug for the treatment of wild-type K-RAS colorectal cancer (CRC). It improves the overall survival of patients. However, acquired resistance prevents its clinical efficacy. Tumor heterogeneity may be a nonnegligible reason for cetuximab resistance. We attempted to explore the corresponding molecular mechanism.

METHODS

Cetuximab-resistant CRC cell RKO and cetuximab-sensitive CRC cell Caco-2 were applied in this study. Cells were centrifuged to determine the concentration in the culture supernatant (CS). MTT, EdU, and colony formation assays were utilized to evaluate cell survival and proliferation. Chromatin immunoprecipitation (ChIP) and promoter-luciferase reporter assays were employed to confirm the direct binding of transcription factors. Western blot and reverse transcription-polymerase chain reaction (RT-PCR) assays were used to detect the expression of molecular markers in the pathway.

RESULTS

Hepatocyte growth factor (HGF) was up-regulated in RKO cell culture supernatant and induced cetuximab resistance in Caco-2 cells. SRY-Box Transcription Factor 8 (SOX8) bound to the promoter sequence of HGF. HGF activated the HGF/MET bypass pathway and induced cetuximab resistance in Caco-2 cells.

CONCLUSION

The SOX8/HGF/MET axis played a crucial role in the communication between cetuximab-resistant cells and cetuximab-sensitive cells, inducing treatment resistance.

Application Areas of Traditional Molecular Genetic Methods and NGS in relation to Hereditary Urological Cancer Diagnosis

Next generation sequencing (NGS) is widely used for diagnosing hereditary cancer syndromes. Often, exome sequencing and extended gene panel approaches are the only means that can be used to detect a pathogenic germline mutation in the case of multiple primary tumors, early onset, a family history of cancer, or a lack of specific signs associated with a particular syndrome. Certain germline mutations of oncogenes and tumor suppressor genes that determine specific clinical phenotypes may occur in mutation hot spots. Diagnosis of such cases, which involve hereditary cancer, does not require NGS, but may be made using PCR and Sanger sequencing. Diagnostic criteria and professional community guidelines developed for hereditary cancers of particular organs should be followed when ordering molecular diagnostic tests for a patient. This review focuses on urological oncology associated with germline mutations. Clinical signs and genetic diagnostic laboratory tests for hereditary forms of renal cell cancer, prostate cancer, and bladder cancer are summarized. While exome sequencing, or, conversely, traditional molecular genetic methods are the procedure of choice in some cases, in most situations, sequencing of multigene panels that are specifically aimed at detecting germline mutations in early onset renal cancer, prostate cancer, and bladder cancer seems to be the basic solution for molecular genetic diagnosis of hereditary cancers.

Pathological roles of c-Met in bladder cancer: Association with cyclooxygenase-2, heme oxygenase-1, vascular endothelial growth factor-A and programmed death ligand 1

c-Met is a receptor tyrosine kinase that binds a specific ligand, namely hepatocyte growth factor (HGF). The HGF/c-Met system is important for malignant aggressiveness in various types of cancer, including bladder cancer (BC). However, although phosphorylation is the essential step required for biological activation of c-Met, pathological roles of phosphorylated c-Met at the clinical and molecular levels in patients with BC are not fully understood. In the present study, the expression levels of c-Met and the phosphorylation of two of its tyrosine residues (pY1234/pY1235 and pY1349) were immunohistochemically examined in 185 BC tissues. The associations between these expression levels and cancer cell invasion, metastasis, and cyclooxygenase-2 (COX-2), heme oxygenase-1 (HO-1), VEGF-A and programmed death ligand 1 (PD-L1) levels were investigated. c-Met was associated with muscle invasion (P=0.021), as well as the expression levels of HO-1 (P=0.028) and PD-L1 (P<0.001), whereas pY1349 c-Met was associated with muscle invasion (P=0.003), metastasis (P=0.025), and COX-2 (P=0.017), HO-1 (P=0.031) and PD-L1 (P=0.001) expression. By contrast, pY1234/1235 c-Met was associated with muscle invasion and metastasis (P=0.006 and P=0.012, respectively), but not with the panel of cancer-associated molecules. Furthermore, COX-2 and PD-L1 expression were associated with muscle invasion and metastasis, respectively (P=0.045 and P=0.036, respectively). Hence, c-Met serves important roles in muscle invasion by regulating HO-1 and PD-L1, whereas its phosphorylation at Y1349 is associated with muscle invasion and metastasis via the regulation of COX-2, HO-1 and PD-L1 in patients with BC. Furthermore, phosphorylation at Y1234/1235 may lead to muscle invasion and metastasis via alternate mechanisms associated with c-Met and pY1349 c-Met.

Dysregulation of Type II Transmembrane Serine Proteases and Ligand-Dependent Activation of MET in Urological Cancers

Unlike in normal epithelium, dysregulated overactivation of various proteases have been reported in cancers. Degradation of pericancerous extracellular matrix leading to cancer cell invasion by matrix metalloproteases is well known evidence. On the other hand, several cell-surface proteases, including type II transmembrane serine proteases (TTSPs), also induce progression through activation of growth factors, protease activating receptors and other proteases. Hepatocyte growth factor (HGF) known as a multifunctional growth factor that upregulates cancer cell motility, invasiveness, proliferative, and anti-apoptotic activities through phosphorylation of MET (a specific receptor of HGF). HGF secreted as inactive zymogen (pro-HGF) from cancer associated stromal fibroblasts, and the proteolytic activation by several TTSPs including matriptase and hepsin is required. The activation is strictly regulated by HGF activator inhibitors (HAIs) in physiological condition. However, downregulation is frequently observed in cancers. Indeed, overactivation of MET by upregulation of matriptase and hepsin accompanied by the downregulation of HAIs in urological cancers (prostate cancer, renal cell carcinoma, and bladder cancer) are also reported, a phenomenon observed in cancer cells with malignant phenotype, and correlated with poor prognosis. In this review, we summarized current reports focusing on TTSPs, HAIs, and MET signaling axis in urological cancers.

Case of Hereditary Papillary Renal Cell Carcinoma Type I in a Patient With a Germline MET Mutation in Russia

Hereditary papillary renal carcinoma (HPRC) is a rare autosomal dominant disease characterized by the development of multiple papillary type I renal cell carcinomas. This hereditary kidney cancer form is caused by activating mutations in MET. Descriptions of patients with HPRC are scarce in the world literature, and no cases have been described in open sources in Russia. Here, we describe a 28-year-old female Russian patient with 7 and 10 primary papillary renal cell carcinomas in the left and right kidneys, respectively. The patient did not have a family history of any of the known hereditary cancer syndromes. A comprehensive medical examination was performed in 2016 including computed tomography and pathomorphological analysis. The observed tumors were resected in a two-step surgical treatment. In February 2019, no sign of disease progression was detected in follow-up medical examination. Molecular genetic analysis revealed the germline heterozygous missense variant in MET: c.3328G>A (p.V1110I; CM990852). We have discussed the biological effects of the detected mutation and the utility of DNA diagnostics for treating patients with HPRC.

Management of Adverse Events Associated with Cabozantinib Therapy in Renal Cell Carcinoma

Cabozantinib was recently approved for the treatment of advanced renal cell carcinoma (RCC) after treatment with vascular endothelial growth factor (VEGF)-targeted therapy. Cabozantinib is a multikinase inhibitor targeting VEGF receptor (VEGFR) 2, mesenchymal-epithelial transition receptor, and "anexelekto" receptor tyrosine kinase. A 60-mg daily dose led to improved overall survival and progression-free survival (PFS) versus everolimus in advanced RCC patients as a second- or later-line treatment in the METEOR trial. Improved PFS with cabozantinib versus sunitinib has also been demonstrated in the first-line setting in CABOSUN. However, cabozantinib, like other VEGFR inhibitors, is associated with toxicity that may affect the patient's quality of life. The most frequent adverse events (AEs) are diarrhea, fatigue, hypertension, hand-foot syndrome, weight loss, nausea, and stomatitis. This article summarizes the safety profile of cabozantinib in RCC patients and offers guidance for the management of these AEs. We discuss the underlying mechanisms of these AEs and, based on our experiences with cabozantinib and other multikinase inhibitors, we present approaches to manage toxicity. Prophylactic and therapeutic solutions are available to help with the management of toxicity associated with cabozantinib, and adequate interventions can ensure optimum adherence and maximize patient outcomes.

IMPLICATIONS FOR PRACTICE

Cabozantinib leads to improved survival outcomes in renal cell carcinoma patients compared with everolimus. However, management of the adverse event profile is crucial to achieve optimum adherence and outcomes with the use of cabozantinib. This review aims to provide appropriate guidance that will minimize the impact of adverse events and help to maximize the utility of this agent in patients with advanced renal cell carcinoma.

Renal Cell Tumors: Understanding Their Molecular Pathological Epidemiology and the 2016 WHO Classification

Accumulating evidence suggests that renal cell tumors represent a group of histologically and molecularly heterogeneous diseases, even within the same histological subtype. In accordance with the increased understanding of the morphological, immunohistochemical, molecular, and epidemiological characteristics of renal cell tumors, the World Health Organization (WHO) classification of renal cell tumors has been modified. This review provides perspectives on both new and current subtypes of renal cell tumors, as well as on the emerging/provisional renal cell carcinomas in the new 2016 WHO classification, which focuses on features of their molecular pathological epidemiology. The WHO classification will require additional revisions to enable the classification of renal cell tumors as clinically meaningful subtypes and provide a better understanding of the unique characteristics of renal cell tumors.

Translocation Renal Cell Carcinoma: An Update on Clinicopathological and Molecular Features

Microphthalmia-associated transcription (MiT) family translocation renal cell carcinoma (tRCC) comprises Xp11 tRCC and t(6;11) RCC. Due to the presence of fusion genes, Xp11 tRCC and t(6;11) RCC are also known as TFE3- and TFEB-rearranged RCC, respectively. TFE3 and TFEB belong to the MiT family, which regulates melanocyte and osteoclast differentiation, and TFE3- and TFEB-rearranged RCC show characteristic clinicopathological and immunohistochemical features. Recent studies identified the fusion partner-dependent clinicopathological and immunohistochemical features in TFE3-rearranged RCC. Furthermore, RCC with chromosome 6p amplification, including TFEB, was identified as a unique subtype of RCC, along with ALK-rearranged RCC. This review summarizes these recent advancements in our tRCC-related knowledge.

PIK3CA hotspot mutations differentially impact responses to MET targeting in MET-driven and non-driven preclinical cancer models

Background

The MET receptor tyrosine kinase represents a promising target in cancer. PIK3CA activating mutations are common in several tumor types and can potentially confer resistance to anti-receptor tyrosine kinase therapy.

Methods

MET and/or PI3K pathway inhibition was assessed in NIH3T3 cells harboring MET-activating point mutation with or without ectopic expression of PIK3CA^E545K and PIK3CA^H1047R, as well as in MET-expressing head and neck cancer cells with endogenous PIK3CA mutations. Endpoints included PI3K pathway activation, cell proliferation, colony-forming ability, cell death, wound-healing, and an in vivo model.

Results

PIK3CA^E545K and PIK3CA^H1047R confer resistance to MET inhibition in MET-driven models. PIK3CA^H1047R was more potent than PIK3CA^E545K at inducing resistance in PI3K pathway activation, cell proliferation, colony-forming ability, induction of cell death and wound-healing upon MET inhibition. Resistance to MET inhibition could be synergistically overcome by co-targeting PI3K. Furthermore, combined MET/PI3K inhibition led to enhanced anti-tumor activity in vivo in tumors harboring PIK3CA^H1047R. In head and neck cancer cells the combination of MET/PI3K inhibitors led to more-than-additive effects.

Conclusions

PIK3CA mutations can lead to resistance to MET inhibition, supporting future clinical evaluation of combinations of PI3K and MET inhibitors in common scenarios of malignant neoplasms featuring aberrant MET expression and PIK3CA mutations.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-017-0660-5) contains supplementary material, which is available to authorized users.

MET exon 14 juxtamembrane splicing mutations: clinical and therapeutical perspectives for cancer therapy

The MET proto-oncogene plays crucial roles in cell growth and proliferation, survival and apoptosis, epithelial-mesenchymal transition (EMT) and invasion, potentially conditioning the development and progression of the carcinogenesis process. The MET-associated aberrant signaling could be triggered by a variety of mechanisms, such as mutations, gene amplification, increased gene copy number and Met/HGF protein expression. Among the various MET alterations, MET exon 14 splicing abnormalities, causing the loss of the Met juxtamembrane (JM) domain, recently emerged as a new potential oncogenic driver and have been identified and validated across different cancer and histology subtypes. Moreover, this aberration was found to be mutually exclusive with other recognized drivers, thus strongly nominating its potential oncogenic role. Recently, the clinical activity of anti-Met-targeted therapy was demonstrated particularly in patients harboring MET exon 14 skipping lung cancer, resulting in a renewed enthusiasm to further test MET precision therapy in prospective trials. In this review, the key preclinical and clinical data regarding MET exon 14 skipping splicing variants as an actionable genomic aberration in cancer are described, and the perspectives deriving from the validation of such alteration as a potential target, which may further allow driving the therapeutic approach in this molecularly selected patients' subgroup, are explored.

Clinical use of cabozantinib in the treatment of advanced kidney cancer: efficacy, safety, and patient selection

Clear cell (cc) renal cell carcinoma (RCC) is the most common type of cancer found in the kidney accounting for ~90% of all kidney cancers. In 2012, there were ~337,000 new cases of RCC diagnosed worldwide with an estimated 143,000 deaths, with the highest incidence and mortality in Western countries. Despite improvements in cancer control achieved with VEGF- and mTOR-targeted therapy for RCC, progression remains virtually universal and additional therapies are needed. The pivotal results of the METEOR trial led to cabozantinib's designation as a breakthrough drug by the US Food and Drug Administration and its approval for treatment of advanced RCC in 2016. Subsequent data from the CABOSUN trial, where caboxantinib is compared with sunitinib, will provide information on the relative activity of cabozantinib as first-line therapy for ccRCC. We review the development of cabozantinib in advanced RCC and its role in the treatment landscape for advanced RCC.

c-Met as a Target for Personalized Therapy

MET and its ligand HGF are involved in many biological processes, both physiological and pathological, making this signaling pathway an attractive therapeutic target in oncology. Downstream signaling effects are transmitted via mitogen-activated protein kinase (MAPK), PI3K (phosphoinositide 3-kinase protein kinase B)/AKT, signal transducer and activator of transcription proteins (STAT), and nuclear factor-κB. The final output of the terminal effector components of these pathways is activation of cytoplasmic and nuclear processes leading to increases in cell proliferation, survival, mobilization and invasive capacity. In addition to its role as an oncogenic driver, increasing evidence implicates MET as a common mechanism of resistance to targeted therapies including EGFR and VEGFR inhibitors. In the present review, we summarize the current knowledge on the role of the HGF-MET signaling pathway in cancer and its therapeutic targeting (HGF activation inhibitors, HGF inhibitors, MET antagonists and selective/nonselective MET kinase inhibitors). Recent advances in understanding the role of this pathway in the resistance to current anticancer strategies used in lung, kidney and pancreatic cancer are discussed.

c-Met as a Target for Personalized Therapy

MET and its ligand HGF are involved in many biological processes, both physiological and pathological, making this signaling pathway an attractive therapeutic target in oncology. Downstream signaling effects are transmitted via mitogen-activated protein kinase (MAPK), PI3K (phosphoinositide 3-kinase protein kinase B)/AKT, signal transducer and activator of transcription proteins (STAT), and nuclear factor-κB. The final output of the terminal effector components of these pathways is activation of cytoplasmic and nuclear processes leading to increases in cell proliferation, survival, mobilization and invasive capacity. In addition to its role as an oncogenic driver, increasing evidence implicates MET as a common mechanism of resistance to targeted therapies including EGFR and VEGFR inhibitors. In the present review, we summarize the current knowledge on the role of the HGF-MET signaling pathway in cancer and its therapeutic targeting (HGF activation inhibitors, HGF inhibitors, MET antagonists and selective/nonselective MET kinase inhibitors). Recent advances in understanding the role of this pathway in the resistance to current anticancer strategies used in lung, kidney and pancreatic cancer are discussed.

Understanding and overcoming the mechanisms of primary and acquired resistance to abiraterone and enzalutamide in castration resistant prostate cancer

In recent years, in castration resistant prostate cancer (CRPC), several new drugs have been approved that prolong overall survival, including enzalutamide and abiraterone, two new-generation hormonal therapies. Despite the demonstrated benefit of these agents, not all patients with CRPC are responsive to treatment, the gain in median progression-free survival with these therapies compared to standard of care is, rather disappointingly, still less than six months and the appearance of acquired resistance is almost universal. Approximately one third of patients treated with abiraterone and 25% of those treated with enzalutamide show primary resistance to these agents. Even if the mechanisms of resistance to these agents are not fully defined, many hypotheses are emerging, including systemic and intratumoral androgen biosynthesis up-regulation, androgen receptor (AR) gene mutations and amplifications, alteration of pathways involved in cross-talk with AR signaling, glucocorticoid receptor overexpression, neuroendocrine differentiation, immune system deregulation and others. The aim of this paper is to review currently available data about mechanisms of resistance to abiraterone and enzalutamide, and to discuss how these mechanisms could be potentially overcome through novel therapeutic agents.