Myoferlin Is a Key Regulator of EGFR Activity in Breast Cancer

p97/VCP Promotes the Recycling of Endocytic Cargo

The endocytic pathway is of central importance for eukaryotic cells, as it enables uptake of extracellular materials, membrane protein quality control and recycling, as well as modulation of receptor signaling. While the ATPase p97 (VCP, Cdc48) has been found to be involved in the fusion of early endosomes and endolysosomal degradation, its role in endocytic trafficking is still incompletely characterized. Here, we identify myoferlin (MYOF), a ferlin family member with functions in membrane trafficking and repair, as a hitherto unknown p97 interactor. The interaction of MYOF with p97 depends on the cofactor PLAA previously linked to endosomal sorting. Besides PLAA, shared interactors of p97 and MYOF comprise several proteins involved in endosomal recycling pathways, including Rab11, Rab14, and the transferrin receptor CD71. Accordingly, a fraction of p97 and PLAA localizes to MYOF-, Rab11-, and Rab14-positive endosomal compartments. Pharmacological inhibition of p97 delays transferrin recycling, indicating that p97 promotes not only the lysosomal degradation, but also the recycling of endocytic cargo.

Otoferlin as a multirole Ca2+ signaling protein: from inner ear synapses to cancer pathways

Humans have six members of the ferlin protein family: dysferlin, myoferlin, otoferlin, fer1L4, fer1L5, and fer1L6. These proteins share common features such as multiple Ca2+-binding C2 domains, FerA domains, and membrane anchoring through their single C-terminal transmembrane domain, and are believed to play a key role in calcium-triggered membrane fusion and vesicle trafficking. Otoferlin plays a crucial role in hearing and vestibular function. In this review, we will discuss how we see otoferlin working as a Ca2+-dependent mechanical sensor regulating synaptic vesicle fusion at the hair cell ribbon synapses. Although otoferlin is also present in the central nervous system, particularly in the cortex and amygdala, its role in brain tissues remains unknown. Mutations in the OTOF gene cause one of the most frequent genetic forms of congenital deafness, DFNB9. These mutations produce severe to profound hearing loss due to a defect in synaptic excitatory glutamatergic transmission between the inner hair cells and the nerve fibers of the auditory nerve. Gene therapy protocols that allow normal rescue expression of otoferlin in hair cells have just started and are currently in pre-clinical phase. In parallel, studies have linked ferlins to cancer through their effect on cell signaling and development, allowing tumors to form and cancer cells to adapt to a hostile environment. Modulation by mechanical forces and Ca2+ signaling are key determinants of the metastatic process. Although ferlins importance in cancer has not been extensively studied, data show that otoferlin expression is significantly associated with survival in specific cancer types, including clear cell and papillary cell renal carcinoma, and urothelial bladder cancer. These findings indicate a role for otoferlin in the carcinogenesis of these tumors, which requires further investigation to confirm and understand its exact role, particularly as it varies by tumor site. Targeting this protein may lead to new cancer therapies.

Identification of tumor antigens and immune subtypes of acute myeloid leukemia for mRNA vaccine development

BACKGROUND

Acute myeloid leukemia (AML) is a highly aggressive hematological malignancy, and there has not been any significant improvement in therapy of AML over the past several decades. The mRNA vaccines have become a promising strategy against multiple cancers, however, its application on AML remains undefined. In this study, we aimed to identify novel antigens for developing mRNA vaccines against AML and explore the immune landscape of AML to select appropriate patients for vaccination.

METHODS

Genomic data and gene mutation data were retrieved from TCGA, GEO and cBioPortal, respectively. GEPIA2 was used to analyze differentially expressed genes. The single cell RNA-seq database Tumor Immune Single-cell Hub (TISCH) was used to explore the association between the potential tumor antigens and the infiltrating immune cells in the bone marrow. Consensus clustering analysis was applied to identify distinct immune subtypes. The correlation between the abundance of antigen presenting cells and the expression level of antigens was evaluated using Spearman correlation analysis. The characteristics of the tumor immune microenvironment in each subtype were investigated based on single-sample gene set enrichment analysis.

RESULTS

Five potential tumor antigens were identified for mRNA vaccine from the pool of overexpressed and mutated genes, including CDH23, LRP1, MEFV, MYOF and SLC9A9, which were associated with infiltration of antigen-presenting immune cells (APCs). AML patients were stratified into two immune subtypes Cluster1 (C1) and Cluster2 (C2), which were characterized by distinct molecular and clinical features. C1 subtype demonstrated an immune-hot and immunosuppressive phenotype, while the C1 subtype had an immune-cold phenotype. Furthermore, the two immune subtype showed remarkably different expression of immune checkpoints, immunogenic cell death modulators and human leukocyte antigens.

CONCLUSION

CDH23, LRP1, MEFV, MYOF and SLC9A9 were potential antigens for developing AML mRNA vaccine, and AML patients in immune subtype 1 were suitable for vaccination.

HBZ upregulates myoferlin expression to facilitate HTLV-1 infection

The complex retrovirus, human T-cell leukemia virus type 1 (HTLV-1), primarily infects CD4+ T-cells in vivo. Infectious spread within this cell population requires direct contact between virally-infected and target cells. The HTLV-1 accessory protein, HBZ, was recently shown to enhance HTLV-1 infection by activating intracellular adhesion molecule 1 (ICAM-1) expression, which promotes binding of infected cells to target cells and facilitates formation of a virological synapse. In this study we show that HBZ additionally enhances HTLV-1 infection by activating expression of myoferlin (MyoF), which functions in membrane fusion and repair and vesicle transport. Results from ChIP assays and quantitative reverse transcriptase PCR indicate that HBZ forms a complex with c-Jun or JunB at two enhancer sites within the MYOF gene and activates transcription through recruitment of the coactivator p300/CBP. In HTLV-1-infected T-cells, specific inhibition of MyoF using the drug, WJ460, or shRNA-mediated knockdown of MyoF reduced infection efficiency. This effect was associated with a decrease in cell adhesion and an intracellular reduction in the abundance of HTLV-1 envelope (Env) surface unit (SU) and transmembrane domain (TM). Lysosomal protease inhibitors partially restored SU levels in WJ460-treated cells, and SU localization to LAMP-2 sites was increased by MyoF knockdown, suggesting that MyoF restricts SU trafficking to lysosomes for degradation. Consistent with these effects, less SU was associated with cell-free virus particles. Together, these data suggest that MyoF contributes to HTLV-1 infection through modulation of Env trafficking and cell adhesion.

Myoferlin disturbs redox equilibrium to accelerate gastric cancer migration

Objective

In contrast to normal cells, in which reactive oxygen species (ROS) are maintained in redox equilibrium, cancer cells are characterized by ectopic ROS accumulation. Myoferlin, a newly identified oncogene, has been associated with tumor metastasis, intracellular ROS production, and energy metabolism. The mechanism by which myoferlin regulates gastric cancer cell migration and ROS accumulation has not been determined.

Methods

Myoferlin expression, intracellular ROS levels, the ratios of reduced to oxidized glutathione (GSH/GSSG) and nicotinamide adenine dinucleotide phosphate (NADPH/NADP+) and migratory ability were measured in gastric cancer cells in vitro and in the TCGA and GEO databases in silico.

Results

Myoferlin was found to be more highly expressed in tumor than in normal tissues of gastric cancer patients, with higher expression of Myoferlin associated with shorter survival time. Myoferlin was associated with significantly higher intracellular ROS levels and enhanced migration of gastric cancer cells. N-acetyl-L-cysteine (NAC), a potent inhibitor of ROS, inhibited Myoferlin-induced ROS accumulation and cell migration.

Conclusions

Myoferlin is a candidate prognostic biomarker for gastric cancer and plays an essential role in regulating redox equilibrium and gastric cancer cell migration. Myoferlin may also be a new target for treatment of patients with gastric cancer.

Neoexpression of JUNO in Oral Tumors Is Accompanied with the Complete Suppression of Four Other Genes and Suggests the Application of New Biomarker Tools

Background. Our study describes the neoexpression (Juno) and suppression (catsperD, dysferlin, Fer1L5 and otoferlin) of selected genes in oral squamous cell carcinomas (OSCCs). As the expression pattern of these genes allows a “yes” or “no” statement by exhibiting an inverse expression pattern in malignant versus benign tissues, they represent potential biomarkers for the characterization of oral malignancies, particularly OSCCs. Methods. Differential expression analyses of selected genes of interest were examined by quantitative PCR of oral cancer tissues compared to normal. Results. Five candidates out of initially nine genes were examined, demonstrating Juno as a putative new tumor marker selectively expressed in OSCCs. Interestingly, the expression of four other genes in benign tissues was completely repressed in tumor tissues with a specificity and sensitivity of 100%. No correlation was observed regarding patients’ sex, tumor staging and grading, and tumor site. Conclusion. The present study shows novel candidates that might be useful tools for oral cancer diagnosis. The neoexpression of Juno in cancerous tissues makes it a promising target molecule regarding its potential in diagnosis as well a therapeutic tool. Moreover, our observations suggest that also the repression of gene expression can be used for diagnosing—at least—OSCCs.

c-Met and EPHA7 Receptor Tyrosine Kinases Are Related to Prognosis in Clear Cell Renal Cell Carcinoma: Focusing on the Association with Myoferlin Expression

Receptor tyrosine kinases (RTKs) are important targets for clear cell renal cell carcinoma (ccRCC) treatment. Myoferlin is a strong regulator of RTKs. To identify myoferlin-associated RTKs and their prognostic implications in ccRCC, we investigated the expression of RTKs and myoferlin using proteome-based evaluation and immunohistochemical staining in tissue microarray. Multivariate Cox analysis adjusted for TNM stage and WHO grade was performed (n = 410 and 506). Proteomic analysis suggested c-Met and EPHA7 as novel candidates for myoferlin-associated RTKs. We immunohistochemically validated the positive association between c-Met and myoferlin expression. High c-Met expression was independently associated with overall (hazard ratio (HR) = 1.153-2.919) and cancer-specific survival (HR = 1.150-3.389). The prognostic effect of high c-Met expression was also determined in an independent cohort (overall survival, HR = 1.503-3.771). Although expression of EPHA7 and myoferlin was not correlated, EPHA7 expression was independently associated with progression-free (HR = 1.237-4.319) and cancer-specific survival (HR = 1.214-4.558). In addition, network-based prioritization showed co-functional enrichment of c-Met and myoferlin, suggesting a novel regulatory function of myoferlin in c-Met signaling. This study indicates that c-Met and EPHA7 might be useful prognostic biomarkers, and the presumed myoferlin/c-Met pathway could be a novel therapeutic target in ccRCC.

The 3D in vivo chorioallantoic membrane model and its role in breast cancer research

PURPOSE

We aimed to evaluate the role of the chorioallantoic membrane model (CAM) in breast cancer research.

METHODS

The following is an overview of the use of the CAM in the field of breast cancer research based on a PubMed literature query.

RESULTS

The CAM is a 3D in vivo model that can be used for the analysis of tumor growth, biology and angiogenesis of primary tumor tissue or tumor cell lines. The CAM model has been used in breast cancer research for drug testing, migration assays and the evaluation of vascularization, amongst others. The CAM model is a valuable method that offers a better imitation of the physiological phenomena compared to 2D or 3D in vitro models.

CONCLUSION

The CAM model has primarily and successfully been utilized for the assessment of the tumor biology of established breast cancer cell lines. Further, the CAM model is a promising method to analyze patient derived primary tumor material and could be used as a "patient-specific 3D-tumor-therapy-model" for the cost-efficient evaluation of anti-cancer drugs to find the optimal treatment for breast cancer patients.

Comprehensive Analysis of Myoferlin in Human Pancreatic Cancer via Bioinformatics

Pancreatic cancer is the fourth leading cause of cancer-related death and urgently needs biomarkers for clinical diagnosis and prognosis. It has been reported that myoferlin (MYOF) is implicated in the regulation of proliferation, invasion, and migration of tumor cells in many cancers including pancreatic cancer. To confirm the prognostic value of MYOF in pancreatic cancer, a comprehensive cancer versus healthy people analysis was conducted using public data. MYOF mRNA expression levels were compared in many kinds of cancers including pancreatic cancer via the Oncomine and Gene Expression Profiling Interactive Analysis (GEPIA) databases. The results have shown that MYOF mRNA expression levels were upregulated in most types of cancers, especially in pancreatic cancer, compared with healthy people's tissues. Data from the Cancer Cell Line Encyclopedia (CCLE) and European Bioinformatics Institute (EMBL-EML) database also revealed that MYOF mRNA is highly expressed in most cancer cells, particularly in pancreatic cancer cell lines. Furthermore, the prognostic value of MYOF was evaluated using GEPIA and Long-term Outcome and Gene Expression Profiling Database of pan-cancers (LOGpc) database. Higher expression of MYOF was associated with poorer overall survival, especially in the lower stage and lower grade. Coexpressed genes, possible regulators, and the correlation between MYOF expressions were analyzed via the GEPIA and LinkedOmics database. Nineteen coexpressed genes were identified, and most of these genes were related to cancer. The Tumor Immune Estimation Resource (TIMER) database was used to analyze the correlation between MYOF and immune response. Notably, we found that MYOF might have a potential novel immune regulatory role in tumor immunity. These results support that MYOF is a candidate prognostic biomarker for pancreatic cancer, which calls for further genomics research of pancreatic cancer and deeply functional studies on MYOF.

Identification of Myoferlin, a Potential Serodiagnostic Antigen of Clonorchiasis, via Immunoproteomic Analysis of Sera From Different Infection Periods and Excretory-Secretory Products of Clonorchis sinensis

Clonorchiasis, which is caused by Clonorchis sinensis, is an important foodborne disease worldwide. The excretory-secretory products (ESPs) of C. sinensis play important roles in host-parasite interactions by acting as causative agents. In the present study, the ESPs and sera positive for C. sinensis were collected to identify proteins specific to the sera of C. sinensis (i.e., proteins that do not cross-react with Fasciola hepatica and Schistosoma japonicum) at different infection periods. Briefly, white Japanese rabbits were artificially infected with C. sinensis, and their sera were collected at 7 days post-infection (dpi), 14 dpi, 35 dpi, and 77 dpi. To identify the specific proteins in C. sinensis, a co-immunoprecipitation (Co-IP) assay was conducted using shotgun liquid chromatography tandem-mass spectrometry (LC-MS/MS) to pull down the sera roots of C. sinensis, F. hepatica, and S. japonicum. For the annotated proteins, 32, 18, 39, and 35 proteins specific to C. sinensis were pulled down by the infected sera at 7, 14, 35, and 77 dpi, respectively. Three proteins, Dynein light chain-1, Dynein light chain-2 and Myoferlin were detected in all infection periods. Of these proteins, myoferlin is known to be overexpressed in several human cancers and could be a promising biomarker and therapeutic target for cancer cases. Accordingly, this protein was selected for further studies. To achieve a better expression, myoferlin was truncated into two parts, Myof1 and Myof2 (1,500 bp and 810 bp), based on the antigenic epitopes provided by bioinformatics. The estimated molecular weight of the recombinant proteins was 57.3 ku (Myof1) and 31.3 ku (Myof2). Further, both Myof1 and Myof2 could be probed by the sera from rabbits infected with C. sinensis. No cross-reaction occurred with the positive sera of S. japonica, F. hepatica, and negative controls. Such findings indicate that myoferlin may be an important diagnostic antigen present in the ESPs. Overall, the present study provides new insights into proteomic changes between ESPs and hosts in different infection periods by LC-MS/MS. Moreover, myoferlin, as a biomarker, may be used to develop an objective method for future diagnosis of clonorchiasis.

Establishment of oxaliplatin-resistant gastric cancer organoids: importance of myoferlin in the acquisition of oxaliplatin resistance

BACKGROUND

The attainment of drug resistance in gastric cancer (GC) is a problematic issue. Although many studies have shown that cancer stem cells (CSCs) play an important role in the acquisition of drug resistance, there is no clinically available biomarker for predicting oxaliplatin (L-OHP) resistance in relation to CSCs. Organoid technology, a novel 3D cell culture system, allows harboring of patient-derived cancer cells containing abundant CSCs using niche factors in a dish.

METHODS

In this study, we established L-OHP-resistant gastric cancer organoids (GCOs) and evaluated their gene expression profile using microarray analysis. We validated the upregulated genes in the L-OHP-resistant GCOs compared to their parental GCOs to find a gene responsible for L-OHP resistance by qRT-PCR, immunohistochemistry, in vitro, and in vivo experiments.

RESULTS

We found myoferlin (MYOF) to be a candidate gene through microarray analysis. The results from cell viability assays and qRT-PCR showed that high expression of MYOF correlated significantly with the IC50 of L-OHP in GCOs. Immunohistochemistry of MYOF in GC tissue samples revealed that high expression of MYOF was significantly associated with poor prognosis, T grade, N grade, and lymphatic invasion, and showed MYOF to be an independent prognostic indicator, especially in the GC patients treated with platinum-based chemotherapy. The knockdown of MYOF repressed L-OHP resistance, cell growth, stem cell features, migration, invasion, and in vivo tumor growth.

CONCLUSIONS

Our results suggest that MYOF is highly involved in L-OHP resistance and tumor progression in GC. MYOF could be a promising biomarker and therapeutic target for L-OHP-resistant GC cases.

Coupling of Cell Surface Biotinylation and SILAC-Based Quantitative Proteomics Identified Myoferlin as a Potential Therapeutic Target for Nasopharyngeal Carcinoma Metastasis

Distant metastasis is a major cause of treatment failure in nasopharyngeal carcinoma (NPC) patients. Cell surface proteins represent attractive targets for cancer diagnosis or therapy. However, the cell surface proteins associated with NPC metastasis are poorly understood. To identify potential therapeutic targets for NPC metastasis, we isolated cell surface proteins from two isogenic NPC cell lines, 6-10B (low metastatic) and 5-8F (highly metastatic), through cell surface biotinylation. Stable isotope labeling by amino acids in cell culture (SILAC) based proteomics was applied to comprehensively characterize the cell surface proteins related with the metastatic phenotype. We identified 294 differentially expressed cell surface proteins, including the most upregulated protein myoferlin (MYOF), two receptor tyrosine kinases(RTKs) epidermal growth factor receptor (EGFR) and ephrin type-A receptor 2 (EPHA2) and several integrin family molecules. These differentially expressed proteins are enriched in multiple biological pathways such as the FAK-PI3K-mTOR pathway, focal adhesions, and integrin-mediated cell adhesion. The knockdown of MYOF effectively suppresses the proliferation, migration and invasion of NPC cells. Immunohistochemistry analysis also showed that MYOF is associated with NPC metastasis. We experimentally confirmed, for the first time, that MYOF can interact with EGFR and EPHA2. Moreover, MYOF knockdown could influence not only EGFR activity and its downstream epithelial–mesenchymal transition (EMT), but also EPHA2 ligand-independent activity. These findings suggest that MYOF might be an attractive potential therapeutic target that has double effects of simultaneously influencing EGFR and EPHA2 signaling pathway. In conclusion, this is the first study to profile the cell surface proteins associated with NPC metastasis and provide valuable resource for future researches.

An Emerging Therapeutic Approach by Targeting Myoferlin (MYOF) for Malignant Tumors

Myoferlin (MYOF), as a member of the ferlin family, is a type II transmembrane protein with a single transmembrane domain at the carbon terminus. Studies have shown that MYOF is involved in pivotal physiological functions related to numerous cell membranes, such as extracellular secretion, endocytosis cycle, vesicle trafficking, membrane repair, membrane receptor recycling, and secreted protein efflux. Recently, the studies have also revealed that MYOF is overexpressed in a variety of cancers such as colorectal cancer, pancreatic cancer, breast cancer, melanoma, gastric cancer, and non-small-cell lung cancer. High expression of MYOF is associated with the high invasion of tumors and poor clinical prognosis. MYOF medicates the expression, secretion, and distribution of proteins, which were closely related to cancers, as well as the energy utilization of cancer cells, lipid metabolism and other physiological activities by regulating the physiological processes of membrane transport. In this short article, we briefly summarize the latest progress related to MYOF, indicating that small molecule inhibitors targeting the MYOF-C2D domain can selectively inhibit the proliferation and migration of cancer cells, and MYOF may be a promising target for the treatment of malignant tumors.

The Role of Mitochondria in the Chemoresistance of Pancreatic Cancer Cells

The first-line chemotherapies for patients with unresectable pancreatic cancer (PC) are 5-fluorouracil (5-FU) and gemcitabine therapy. However, due to chemoresistance the prognosis of patients with PC has not been significantly improved. Mitochondria are essential organelles in eukaryotes that evolved from aerobic bacteria. In recent years, many studies have shown that mitochondria play important roles in tumorigenesis and may act as chemotherapeutic targets in PC. In addition, according to recent studies, mitochondria may play important roles in the chemoresistance of PC by affecting apoptosis, metabolism, mtDNA metabolism, and mitochondrial dynamics. Interfering with some of these factors in mitochondria may improve the sensitivity of PC cells to chemotherapeutic agents, such as gemcitabine, making mitochondria promising targets for overcoming chemoresistance in PC.

A potent and selective small molecule inhibitor of myoferlin attenuates colorectal cancer progression

As a pivotal vesicular trafficking protein, Myoferlin (MYOF) has become an attractive target for cancer therapy. However, the roles of MYOF in colorectal cancer invasion remain enigmatic, and MYOF-targeted therapy in this malignancy has not been explored. In the present study, we provided the first functional evidence that MYOF promoted the cell invasion of colorectal cancer. Furthermore, we identified a novel small molecule inhibitor of MYOF (named YQ456) that showed high binding affinity to MYOF (KD  = 37 nM) and excellent anti-invasion capability (IC50  = 110 nM). YQ456 was reported for the first time to interfere with the interactions between MYOF and Ras-associated binding (Rab) proteins at low nanomolar levels. This interference disrupted several vesicle trafficking processes, including lysosomal degradation, exosome secretion, and mitochondrial dynamics. Further, YQ456 exhibited excellent inhibitory effects on the growth and invasiveness of colorectal cancer. As the first attempt, the anticancer efficacy of YQ456 in the patient-derived xenograft (PDX) mouse model indicated that targeting MYOF may serve as a novel and practical therapeutic approach for colorectal cancer.

Otoferlin is a prognostic biomarker in patients with clear cell renal cell carcinoma: A systematic expression analysis

OBJECTIVES

To comprehensively investigate the role of otoferlin as a prognostic and diagnostic biomarker in clear cell renal cell carcinoma.

METHODS

Three independent cohorts were used to study otoferlin in clear cell renal cell carcinoma: The Cancer Genome Atlas cohort (messenger ribonucleic acid expression; clear cell renal cell carcinoma n = 514, normal renal tissue n = 81); study validation cohort (messenger ribonucleic acid expression; clear cell renal cell carcinoma n = 79, normal renal tissue n = 44); and immunohistochemistry cohort (protein expression; clear cell renal cell carcinoma n = 142, normal renal tissue n = 30). Otoferlin gene expressions were extracted from The Cancer Genome Atlas database or determined using quantitative real-time polymerase chain reaction, respectively. Protein expression was assessed using immunohistochemistry staining against otoferlin on tissue microarrays. Correlations between otoferlin messenger ribonucleic acid/protein expression and clinicopathological data/patient survival were statistically tested.

RESULTS

Otoferlin messenger ribonucleic acid expression was significantly upregulated in clear cell renal cell carcinoma compared with normal renal tissue. High expression levels correlated with advanced stage, higher grade and metastatic tumors, accompanied by independent prognostic significance for overall and cancer-specific survival. In contrast, otoferlin protein expression was downregulated in tumor tissue. Although, high otoferlin expression in clear cell renal cell carcinoma was positively correlated with histological grading and independently predictive of a shortened progression-free survival.

CONCLUSION

Our data suggest otoferlin as an indicator of tumor aggressiveness and as a prognostic biomarker for patients with clear cell renal cell carcinoma, leading to the conclusion that otoferlin could promote the malignancy of clear cell renal cell carcinoma.

Molecular Mechanisms to Target Cellular Senescence in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) has emerged as a major cause of cancer-related death and is the most common type of liver cancer. Due to the current paucity of drugs for HCC therapy there is a pressing need to develop new therapeutic concepts. In recent years, the role of Serum Response Factor (SRF) and its coactivators, Myocardin-Related Transcription Factors A and B (MRTF-A and -B), in HCC formation and progression has received considerable attention. Targeting MRTFs results in HCC growth arrest provoked by oncogene-induced senescence. The induction of senescence acts as a tumor-suppressive mechanism and therefore gains consideration for pharmacological interventions in cancer therapy. In this article, we describe the key features and the functional role of senescence in light of the development of novel drug targets for HCC therapy with a focus on MRTFs.

Cancer and pH Dynamics: Transcriptional Regulation, Proteostasis, and the Need for New Molecular Tools

An emerging hallmark of cancer cells is dysregulated pH dynamics. Recent work has suggested that dysregulated intracellular pH (pHi) dynamics enable diverse cancer cellular behaviors at the population level, including cell proliferation, cell migration and metastasis, evasion of apoptosis, and metabolic adaptation. However, the molecular mechanisms driving pH-dependent cancer-associated cell behaviors are largely unknown. In this review article, we explore recent literature suggesting pHi dynamics may play a causative role in regulating or reinforcing tumorigenic transcriptional and proteostatic changes at the molecular level, and discuss outcomes on tumorigenesis and tumor heterogeneity. Most of the data we discuss are population-level analyses; lack of single-cell data is driven by a lack of tools to experimentally change pHi with spatiotemporal control. Data is also sparse on how pHi dynamics play out in complex in vivo microenvironments. To address this need, at the end of this review, we cover recent advances for live-cell pHi measurement at single-cell resolution. We also discuss the essential role for tool development in revealing mechanisms by which pHi dynamics drive tumor initiation, progression, and metastasis.

Functions of Vertebrate Ferlins

Ferlins are multiple-C2-domain proteins involved in Ca²⁺-triggered membrane dynamics within the secretory, endocytic and lysosomal pathways. In bony vertebrates there are six ferlin genes encoding, in humans, dysferlin, otoferlin, myoferlin, Fer1L5 and 6 and the long noncoding RNA Fer1L4. Mutations in DYSF (dysferlin) can cause a range of muscle diseases with various clinical manifestations collectively known as dysferlinopathies, including limb-girdle muscular dystrophy type 2B (LGMD2B) and Miyoshi myopathy. A mutation in MYOF (myoferlin) was linked to a muscular dystrophy accompanied by cardiomyopathy. Mutations in OTOF (otoferlin) can be the cause of nonsyndromic deafness DFNB9. Dysregulated expression of any human ferlin may be associated with development of cancer. This review provides a detailed description of functions of the vertebrate ferlins with a focus on muscle ferlins and discusses the mechanisms leading to disease development.

Novel properties of myoferlin in glucose metabolism via pathways involving modulation of adipose functions

While adipose tissue is required to maintain glucose metabolism, excessive calorie intake induces obesity via mechanisms including accelerated proliferation and differentiation of preadipocytes, leading to insulin resistance. Here, we investigated the role of myoferlin (MYOF), a ferlin family protein, in regulating glucose metabolism by mainly focusing on its unknown role in adipose tissue. Whereas young MYOF knockout (KO) mice on a normal diet showed aggravated glucose tolerance and insulin sensitivity, those on a high-fat diet (HFD) showed preserved glucose tolerance with an attenuated gain of body weight, reduced visceral fat deposits, and less severe fatty liver. The Adipose MYOF expression was reduced by aging but was restored by an HFD along with the retained expression of NFAT transcription factors. Loss-of-function of MYOF in preadipocytes suppressed proliferation and differentiation into mature adipocytes along with the decreased expression of genes involved in adipogenesis. The MYOF expression in preadipocytes was reduced with differentiation. Attenuated obesity in MYOF KO mice on an HFD was also accompanied with increased oxygen consumption by an unidentified mechanism and with reduced adipose inflammation due to less inflammatory macrophages. These insights suggest that the multifunctional roles of MYOF involve the regulation of preadipocyte function and affect glucose metabolism bidirectionally depending on consumed calories.

Myoferlin, a Membrane Protein with Emerging Oncogenic Roles

Myoferlin (MYOF), initially identified in muscle cells, is a member of the Ferlin family involved in membrane fusion, membrane repair, and membrane trafficking. Dysfunction of this protein is associated with muscular dysfunction. Recently, a growing body of studies have identified MYOF as an oncogenic protein. It is overexpressed in a variety of human cancers and promotes tumorigenesis, tumor cell motility, proliferation, migration, epithelial to mesenchymal transition, angiogenesis as well as metastasis. Clinically, MYOF overexpression is associated with poor outcome in various cancers. It can serve as a prognostic marker of human malignant disease. MYOF drives the progression of cancer in various processes, including surface receptor transportation, endocytosis, exocytosis, intercellular communication, fit mitochondrial structure maintenance and cell metabolism. Depletion of MYOF demonstrates significant antitumor effects both in vitro and in vivo, suggesting that targeting MYOF may produce promising clinical benefits in the treatment of malignant disease. In the present article, we reviewed the physiological function of MYOF as well as its role in cancer, thus providing a general understanding for further exploration of this protein.

Myoferlin silencing inhibits VEGFR2-mediated proliferation of metastatic clear cell renal cell carcinoma

Recently, ramucirumab, a drug that targets vascular endothelial growth factor receptor (VEGFR), was clinically approved; therefore, we evaluated VEGFR2 expression and its predictive roles in tumor progression in clear cell renal cell carcinoma (CCRCC). Since we do not have many options for treating aggressive renal cell carcinoma patients, the application of anti-VEGFR2 therapy might be useful. Myoferlin (MYOF) is a 230 kDa transmembrane multi-C2-domain protein that contributes to plasma membrane repair, fusion, and endocytosis and is overexpressed in several invasive cancer cell lines, including breast, pancreas, and malignant melanoma. It forms a complex with VEGFR2 to inhibit VEGFR2 degradation. In this study, a total of 152 patients who had undergone nephrectomy for CCRCC were enrolled. Based on tissue microarray (TMA) blocks, the positive intensity and high proportion of MYOF showed a statistically significant correlation with the negative intensity (p < 0.001) and low proportion (p < 0.001) of VEGFR2, respectively. In addition, Fuhrman’s nuclear grade ≥3 showed a significant correlation with VEGFR2 expression. In multivariate analysis, CCRCC patients with positive MYOF and negative VEGFR2 expression demonstrated poor clinical outcomes. We confirmed that positive MYOF expression and negative VEGFR2 expression were positively correlated in this CCRCC population. Knocking down MYOF in Caki-1 cells resulted in the downregulation of VEGFR2 at both mRNA and protein levels. Wound healing assays revealed that the loss of MYOF in Caki-1 cells decreased cell confluence compared to that in control cells. We demonstrated that MYOF influences cellular proliferation of the metastatic CCRCC cell line by regulating VEGFR2 degradation. Combined therapies targeting the MYOF and VEGFR2 pathways might be effective against metastatic CCRCC to increase patient survival.

Myoferlin, a multifunctional protein in normal cells, has novel and key roles in various cancers

Myoferlin, a protein of the ferlin family, has seven C2 domains and exhibits activity in some cells, including myoblasts and endothelial cells. Recently, myoferlin was identified as a promising target and biomarker in non-small-cell lung cancer, breast cancer, pancreatic adenocarcinoma, hepatocellular carcinoma, colon cancer, melanoma, oropharyngeal squamous cell carcinoma, head and neck squamous cell carcinoma, clear cell renal cell carcinoma and endometrioid carcinoma. This evidence indicated that myoferlin was involved in the proliferation, invasion and migration of tumour cells, the mechanism of which mainly included promoting angiogenesis, vasculogenic mimicry, energy metabolism reprogramming, epithelial-mesenchymal transition and modulating exosomes. The roles of myoferlin in both normal cells and cancer cells are of great significance to provide novel and efficient methods of tumour treatment. In this review, we summarize recent studies and findings of myoferlin and suggest that myoferlin is a novel potential candidate for clinical diagnosis and targeted cancer therapy.

Expression Levels of Therapeutic Targets as Indicators of Sensitivity to Targeted Therapeutics

Cancer precision medicine aims to predict the drug likely to yield the best response for a patient. Genomic sequencing of tumors is currently being used to better inform treatment options; however, this approach has had a limited clinical impact due to the paucity of actionable mutations. An alternative to mutation status is the use of gene expression signatures to predict response. Using data from two large-scale studies, The Genomics of Drug Sensitivity of Cancer (GDSC) and The Cancer Therapeutics Response Portal (CTRP), we investigated the relationship between the sensitivity of hundreds of cell lines to hundreds of drugs, and the relative expression levels of the targets these drugs are directed against. For approximately one third of the drugs considered (73/222 in GDSC and 131/360 in CTRP), sensitivity was significantly correlated with the expression of at least one of the known targets. Surprisingly, for 8% of the annotated targets, there was a significant anticorrelation between target expression and sensitivity. For several cases, this corresponded to drugs targeting multiple genes in the same family, with the expression of one target significantly correlated with sensitivity and another significantly anticorrelated suggesting a possible role in resistance. Furthermore, we identified nontarget genes that are significantly correlated or anticorrelated with drug sensitivity, and find literature linking several to sensitization and resistance. Our analyses provide novel and important insights into both potential mechanisms of resistance and relative efficacy of drugs against the same target.

Ferlin Overview: From Membrane to Cancer Biology

In mammal myocytes, endothelial cells and inner ear cells, ferlins are proteins involved in membrane processes such as fusion, recycling, endo- and exocytosis. They harbour several C2 domains allowing their interaction with phospholipids. The expression of several Ferlin genes was described as altered in several tumoural tissues. Intriguingly, beyond a simple alteration, myoferlin, otoferlin and Fer1L4 expressions were negatively correlated with patient survival in some cancer types. Therefore, it can be assumed that membrane biology is of extreme importance for cell survival and signalling, making Ferlin proteins core machinery indispensable for cancer cell adaptation to hostile environments. The evidences suggest that myoferlin, when overexpressed, enhances cancer cell proliferation, migration and metabolism by affecting various aspects of membrane biology. Targeting myoferlin using pharmacological compounds, gene transfer technology, or interfering RNA is now considered as an emerging therapeutic strategy.

Truncating Variant in Myof Gene Is Associated With Limb-Girdle Type Muscular Dystrophy and Cardiomyopathy

Even though genetic studies of individuals with neuromuscular diseases have uncovered the molecular background of many cardiac disorders such as cardiomyopathies and inherited arrhythmic syndromes, the genetic cause of a proportion of cardiomyopathies associated with neuromuscular phenotype still remains unknown. Here, we present an individual with a combination of cardiomyopathy and limb-girdle type muscular dystrophy where whole exome sequencing identified myoferlin (MYOF)-a member of the Ferlin protein family and close homolog of DYSF-as the most likely candidate gene. The disease-causative role of the identified variant c.[2576delG; 2575G>C], p.G859QfsTer8 is supported by functional studies in vitro using the primary patient's skeletal muscle mesenchymal progenitor cells, including both RNA sequencing and morphological studies, as well as recapitulating the muscle phenotype in vivo in zebrafish. We provide the first evidence supporting a role of MYOF in human muscle disease.

Myoferlin Contributes to the Metastatic Phenotype of Pancreatic Cancer Cells by Enhancing Their Migratory Capacity through the Control of Oxidative Phosphorylation

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest malignancies with an overall survival of 5% and is the second cause of death by cancer, mainly linked to its high metastatic aggressiveness. Accordingly, understanding the mechanisms sustaining the PDAC metastatic phenotype remains a priority. In this study, we generated and used a murine in vivo model to select clones from the human Panc-1 PDAC cell line that exhibit a high propensity to seed and metastasize into the liver. We showed that myoferlin, a protein previously reported to be overexpressed in PDAC, is significantly involved in the migratory abilities of the selected cells. We first report that highly metastatic Panc-1 clones expressed a significantly higher myoferlin level than the corresponding low metastatic ones. Using scratch wound and Boyden’s chamber assays, we show that cells expressing a high myoferlin level have higher migratory potential than cells characterized by a low myoferlin abundance. Moreover, we demonstrate that myoferlin silencing leads to a migration decrease associated with a reduction of mitochondrial respiration. Since mitochondrial oxidative phosphorylation has been shown to be implicated in the tumor progression and dissemination, our data identify myoferlin as a valid potential therapeutic target in PDAC.

Structural Basis for the Distinct Membrane Binding Activity of the Homologous C2A Domains of Myoferlin and Dysferlin

Dysferlin has been implicated in acute membrane repair processes, whereas myoferlin's activity is maximal during the myoblast fusion stage of early skeletal muscle cell development. Both proteins are similar in size and domain structure; however, despite the overall similarity, myoferlin's known physiological functions do not overlap with those of dysferlin. Here we present for the first time the X-ray crystal structure of human myoferlin C2A to 1.9 Å resolution bound to two divalent cations, and compare its three-dimensional structure and membrane binding activities to that of dysferlin C2A. We find that while dysferlin C2A binds membranes in a Ca²⁺-dependent manner, Ca²⁺ binding was the rate-limiting kinetic step for this interaction. Myoferlin C2A, on the other hand, binds two calcium ions with an affinity 3-fold lower than that of dysferlin C2A; and, surprisingly, myoferlin C2A binds only marginally to phospholipid mixtures with a high fraction of phosphatidylserine.

Human colon cancer cells highly express myoferlin to maintain a fit mitochondrial network and escape p53-driven apoptosis

Colon adenocarcinoma is the third most commonly diagnosed cancer and the second deadliest one. Metabolic reprogramming, described as an emerging hallmark of malignant cells, includes the predominant use of glycolysis to produce energy. Recent studies demonstrated that mitochondrial electron transport chain inhibitor reduced colon cancer tumour growth. Accumulating evidence show that myoferlin, a member of the ferlin family, is highly expressed in several cancer types, where it acts as a tumour promoter and participates in the metabolic rewiring towards oxidative metabolism. In this study, we showed that myoferlin expression in colon cancer lesions is associated with low patient survival and is higher than in non-tumoural adjacent tissue. Human colon cancer cells silenced for myoferlin exhibit a reduced oxidative phosphorylation activity associated with mitochondrial fission leading, ROS accumulation, decreased cell growth, and increased apoptosis. We observed the triggering of a DNA damage response culminating to a cell cycle arrest in wild-type p53 cells. The use of a p53 null cell line or a compound able to restore p53 activity (Prima-1) reverted the effects induced by myoferlin silencing, confirming the involvement of p53. The recent identification of a compound interacting with a myoferlin C2 domain and bearing anticancer potency identifies, together with our demonstration, this protein as a suitable new therapeutic target in colon cancer.

Fer1l6 is essential for the development of vertebrate muscle tissue in zebrafish

The precise spatial and temporal expression of genes is essential for proper organismal development. Despite their importance, however, many developmental genes have yet to be identified. We have determined that Fer1l6, a member of the ferlin family of genes, is a novel factor in zebrafish development. We find that Fer1l6 is expressed broadly in the trunk and head of zebrafish larvae and is more restricted to gills and female gonads in adult zebrafish. Using both genetic mutant and morpholino knockdown models, we found that loss of Fer1l6 led to deformation of striated muscle tissues, delayed development of the heart, and high morbidity. Further, expression of genes associated with muscle cell proliferation and differentiation were affected. Fer1l6 was also detected in the C2C12 cell line, and unlike other ferlin homologues, we found Fer1l6 expression was independent of the myoblast-to-myotube transition. Finally, analysis of cell and recombinant protein-based assays indicate that Fer1l6 colocalizes with syntaxin 4 and vinculin, and that the putative C2 domains interact with lipid membranes. We conclude that Fer1l6 has diverged from other vertebrate ferlins to play an essential role in zebrafish skeletal and cardiac muscle development.

Genetics of Human Longevity From Incomplete Data: New Findings From the Long Life Family Study

The special design of the Long Life Family Study provides a unique opportunity to investigate the genetics of human longevity by analyzing data on exceptional lifespans in families. In this article, we performed two series of genome wide association studies of human longevity which differed with respect to whether missing lifespan data were predicted or not predicted. We showed that the use of predicted lifespan is most beneficial when the follow-up period is relatively short. In addition to detection of strong associations of SNPs in APOE, TOMM40, NECTIN2, and APOC1 genes with longevity, we also detected a strong new association with longevity of rs1927465, located between the CYP26A1 and MYOF genes on chromosome 10. The association was confirmed using data from the Health and Retirement Study. We discuss the biological relevance of the detected SNPs to human longevity.

TC2N, a novel oncogene, accelerates tumor progression by suppressing p53 signaling pathway in lung cancer

The protein containing the C2 domain has been well documented for its essential roles in endocytosis, cellular metabolism and cancer. Tac2-N (TC2N) is a tandem C2 domain-containing protein, but its function, including its role in tumorigenesis, remains unknown. Here, we first identified TC2N as a novel oncogene in lung cancer. TC2N was preferentially upregulated in lung cancer tissues compared with adjacent normal lung tissues. High TC2N expression was significantly associated with poor outcome of lung cancer patients. Knockdown of TC2N markedly induces cell apoptosis and cell cycle arrest with repressing proliferation in vitro, and suppresses tumorigenicity in vivo, whereas overexpression of TC2N has the opposite effects both in vitro and in vivo. Using a combination of TCGA database and bioinformatics, we demonstrate that TC2N is involved in regulation of the p53 signaling pathway. Mechanistically, TC2N attenuates p53 signaling pathway through inhibiting Cdk5-induced phosphorylation of p53 via inducing Cdk5 degradation or disrupting the interaction between Cdk5 and p53. Moreover, the blockade of p53 attenuates the function of TC2N knockdown in the regulation of cell proliferation and apoptosis. In addition, downregulated TC2N is involved in the apoptosis of lung cancer cells induced by doxorubicin, leading to p53 pathway activation. Overall, these findings uncover a role for the p53 inactivator TC2N in regulating the proliferation and apoptosis of lung cancer cells. Our present study provides novel insights into the mechanism of tumorigenesis in lung cancer.

A small molecule targeting myoferlin exerts promising anti-tumor effects on breast cancer

Breast cancer is one of the most lethal cancers in women when it reaches the metastatic stage. Here, we screen a library of small molecules for inhibitors of breast cancer cell invasion, and use structure/activity relationship studies to develop a series of small molecules with improved activity. We find WJ460 as one of the lead compounds exerting anti-metastatic activity in the nanomolar range in breast cancer cells. Proteomic and biochemical studies identify myoferlin (MYOF) as the direct target of WJ460. In parallel, loss of MYOF or pharmacological inhibition of MYOF by WJ460 reduces breast cancer extravasation into the lung parenchyma in an experimental metastasis mouse model, which reveals an essential role of MYOF in breast cancer progression. Our findings suggest that MYOF can be explored as a molecular target in breast cancer metastasis and that targeting MYOF by WJ460 may be a promising therapeutic strategy in MYOF-driven cancers.

Improved therapeutics are needed for treating breast cancer. Here they show the druggability of myoferlin with a small molecule inhibitor in breast cancer and demonstrate its anti-breast cancer effects in vitro and in vivo.

Sequencing of Supernumerary Chromosomes of Red Fox and Raccoon Dog Confirms a Non-Random Gene Acquisition by B Chromosomes

B chromosomes (Bs) represent a variable addition to the main karyotype in some lineages of animals and plants. Bs accumulate through non-Mendelian inheritance and become widespread in populations. Despite the presence of multiple genes, most Bs lack specific phenotypic effects, although their influence on host genome epigenetic status and gene expression are recorded. Previously, using sequencing of isolated Bs of ruminants and rodents, we demonstrated that Bs originate as segmental duplications of specific genomic regions, and subsequently experience pseudogenization and repeat accumulation. Here, we used a similar approach to characterize Bs of the red fox (Vulpes vulpes L.) and the Chinese raccoon dog (Nyctereutes procyonoides procyonoides Gray). We confirm the previous findings of the KIT gene on Bs of both species, but demostrate an independent origin of Bs in these species, with two reused regions. Comparison of gene ensembles in Bs of canids, ruminants, and rodents once again indicates enrichment with cell-cycle genes, development-related genes, and genes functioning in the neuron synapse. The presence of B-chromosomal copies of genes involved in cell-cycle regulation and tissue differentiation may indicate importance of these genes for B chromosome establishment.

Myoferlin controls mitochondrial structure and activity in pancreatic ductal adenocarcinoma, and affects tumor aggressiveness

Pancreatic ductal adenocarcinoma (PDAC) is the third leading cause of cancer-related death. Therapeutic options remain very limited and are based on classical chemotherapies. Energy metabolism reprogramming appears as an emerging hallmark of cancer and is considered a therapeutic target with considerable potential. Myoferlin, a ferlin family member protein overexpressed in PDAC, is involved in plasma membrane biology and has a tumor-promoting function. In the continuity of our previous studies, we investigated the role of myoferlin in the context of energy metabolism in PDAC. We used selected PDAC tumor samples and PDAC cell lines together with small interfering RNA technology to study the role of myoferlin in energetic metabolism. In PDAC patients, we showed that myoferlin expression is negatively correlated with overall survival and with glycolytic activity evaluated by ¹⁸F-deoxyglucose positron emission tomography. We found out that myoferlin is more abundant in lipogenic pancreatic cancer cell lines and is required to maintain a branched mitochondrial structure and a high oxidative phosphorylation activity. The observed mitochondrial fission induced by myoferlin depletion led to a decrease of cell proliferation, ATP production, and autophagy induction, thus indicating an essential role of myoferlin for PDAC cell fitness. The metabolic phenotype switch generated by myoferlin silencing could open up a new perspective in the development of therapeutic strategies, especially in the context of energy metabolism.

Myoferlin regulates epithelial cancer cell plasticity and migration through autocrine TGF-β1 signaling

Epithelial cancer cells can undergo an epithelial-mesenchymal transition (EMT), a complex genetic program that enables cells to break free from the primary tumor, breach the basement membrane, invade through the stroma and metastasize to distant organs. Myoferlin (MYOF), a protein involved in plasma membrane function and repair, is overexpressed in several invasive cancer cell lines. Depletion of myoferlin in the human breast cancer cell line MDA-MB-231 (MDA-231^MYOFKD) reduced migration and invasion and caused the cells to revert to an epithelial phenotype. To test if this mesenchymal-epithelial transition was durable, MDA-231^MYOFKD cells were treated with TGF-β1, a potent stimulus of EMT. After 48 hr with TGF-β1, MDA-231^MYOFKD cells underwent an EMT. TGF-β1 treatment also decreased directional cell motility toward more random migration, similar to the highly invasive control cells. To probe the potential mechanism of MYOF function, we examined TGF-β1 receptor signaling. MDA-MB-231 growth and survival has been previously shown to be regulated by autocrine TGF-β1. We hypothesized that MYOF depletion may result in the dysregulation of TGF-β1 signaling, thwarting EMT. To investigate this hypothesis, we examined production of endogenous TGF-β1 and observed a decrease in TGF-β1 protein secretion and mRNA transcription. To determine if TGF-β1 was required to maintain the mesenchymal phenotype, TGF-β receptor signaling was inhibited with a small molecule inhibitor, resulting in decreased expression of several mesenchymal markers. These results identify a novel pathway in the regulation of autocrine TGF-β signaling and a mechanism by which MYOF regulates cellular phenotype and invasive capacity of human breast cancer cells.

Myoferlin is a novel exosomal protein and functional regulator of cancer-derived exosomes

Exosomes are communication mediators participating in the intercellular exchange of proteins, metabolites and nucleic acids. Recent studies have demonstrated that exosomes are characterized by a unique proteomic composition that is distinct from the cellular one. The mechanisms responsible for determining the proteome content of the exosomes remain however obscure. In the current study we employ ultrastructural approach to validate a novel exosomal protein myoferlin. This is a multiple C2-domain containing protein, known for its conserved physiological function in endocytosis and vesicle fusion biology. Emerging studies demonstrate that myoferlin is frequently overexpressed in cancer, where it promotes cancer cell migration and invasion. Our data expand these findings by showing that myoferlin is a general component of cancer cell derived exosomes from different breast and pancreatic cancer cell lines. Using proteomic analysis, we demonstrate for the first time that myoferlin depletion in cancer cells leads to a significantly modulated exosomal protein load. Such myoferlin-depleted exosomes were also functionally deficient as shown by their reduced capacity to transfer nucleic acids to human endothelial cells (HUVEC). Beyond this, myoferlin-depleted cancer exosomes also had a significantly reduced ability to induce migration and proliferation of HUVEC. The present study highlights myoferlin as a new functional player in exosome biology, calling for novel strategies to target this emerging oncogene in human cancer.

Innovative methods for biomarker discovery in the evaluation and development of cancer precision therapies

The discovery of biomarkers able to detect cancer at an early stage, to evaluate its aggressiveness, and to predict the response to therapy remains a major challenge in clinical oncology and precision medicine. In this review, we summarize recent achievements in the discovery and development of cancer biomarkers. We also highlight emerging innovative methods in biomarker discovery and provide insights into the challenges faced in their evaluation and validation.

Inhibition of SHIP2 activity inhibits cell migration and could prevent metastasis in breast cancer cells

Metastasis of breast cancer cells to distant organs is responsible for approximately 50 % in cancer related deaths in women worldwide. SHIP2 is a phosphoinositide 5-phosphatase for PI(3,4,5)P3 and PI(4,5)P2. Through depletion of SHIP2 in triple negative MDA-MB-231 cells and the use of SHIP2 inhibitors, it appeared that cell migration is positively controlled by SHIP2. The effect of SHIP2 on migration, observed in MDA-MB-231 cells, appears to be mediated by PI(3,4)P2. Adhesion on fibronectin is always increased in SHIP2 depleted cells. Apoptosis measured in MDA-MB-231 cells is also increased in SHIP2 depleted cells as compared to control cells. In xenograft mice, SHIP2 depleted MDA-MB-231 cells form significantly smaller tumors compared to control cells and less metastasis detected in lung sections. Our data reveal a general role of SHIP2 in the control of cell migration in breast cancer cells and a second messenger role for PI(3,4)P2 in the migration mechanism. In this model, SHIP2 function on apoptosis on cells incubated in vitro, or in mice tumor digested cells, could account for its role on tumor growth determined in vivo.

Identification of Plasma Membrane Glycoproteins Specific to Human Glioblastoma Multiforme Cells Using Lectin Arrays and LC-MS/MS

Glioblastoma, also known as glioblastoma multiforme (GBM), is the most malignant type of brain cancer and has poor prognosis with a median survival of less than one year. While the structural changes of tumor cell surface carbohydrates are known to be associated with invasive behavior of tumor cells, the cell surface glycoproteins to differentiate the low- and high-grade glioma cells can be potential diagnostic markers and therapeutic targets for GBMs. In the present study, lectin arrays consisting of eight lectins were employed to explore cell surface carbohydrate expression patterns on low-grade oligodendroglioma cells (Hs683) and GBM cells (T98G). Griffonia simplicifolia I (GS I) was found to selectively bind to T98G cells and not to Hs683 cells. For identification of the glioblastoma-specific cell surface markers, the glycoproteins from each cell type were captured by a GS I lectin column and analyzed by LC-MS/MS. The identified proteins from the two cell types were quantified using label-free quantitative analysis based on spectral counting. Of cell surface glycoproteins showing significant increases in T98G cells, five proteins were selected for verification of both protein and glycosylation level changes using Western blot and GS I lectin-based immunosorbent assay.

Emerging Functional Differences between the Synaptotagmin and Ferlin Calcium Sensor Families

The ferlin family proteins have emerged as multi-C2 domain regulators of calcium-triggered membrane fusion and fission events. While initially determined to share many of the features of members of the synaptotagmin family of calcium sensors, ferlins in more recent studies have been found to interact directly with non-neuronal voltage-gated calcium channels and nucleate the assembly of membrane-trafficking protein complexes, functions that distinguish them from the more well studied members of the synaptotagmin family. Here we highlight some of the recent findings that have advanced our understanding of ferlins and their functional differences with the synaptotagmin family.

A muscle-specific protein 'myoferlin' modulates IL-6/STAT3 signaling by chaperoning activated STAT3 to nucleus

Myoferlin, a member of ferlin family of proteins, was first discovered as a candidate gene for muscular dystrophy and cardiomyopathy. Recently, myoferlin was shown to be also expressed in endothelial and cancer cells where it was shown to modulate vascular endothelial growth factor (VEGFR)-2 and epidermal growth factor receptor (EGFR) signaling by enhancing their stability and recycling. Based on these reports, we hypothesized that myoferlin might be regulating IL-6 signaling by modulating IL-6R stabilization and recycling. However, in our immunoprecipitation (IP) experiments, we did not observe myoferlin binding with IL-6R. Instead, we made a novel discovery that in resting cells myoferlin was bound to EHD2 protein and when cells were treated with IL-6, myoferlin dissociated from EHD2 and binds to activated STAT3. Interestingly, myoferlin depletion did not affect STAT3 phosphorylation, but completely blocked STAT3 translocation to nucleus. In addition, inhibition of STAT3 phosphorylation by phosphorylation-defective STAT3 mutants or JAK inhibitor blocked STAT3 binding to myoferlin and nuclear translocation. Myoferlin knockdown significantly decreased IL-6-mediated tumor cell migration, tumorsphere formation and ALDH-positive cancer stem cell population, in vitro. Furthermore, myoferlin knockdown significantly decreased IL-6-meditated tumor growth and tumor metastasis. Based on these results, we have proposed a novel model for the role of myoferlin in chaperoning phosphorylated STAT3 to the nucleus.

Enzymatic cleavage of myoferlin releases a dual C2-domain module linked to ERK signalling

Myoferlin and dysferlin are closely related members of the ferlin family of Ca2+-regulated vesicle fusion proteins. Dysferlin is proposed to play a role in Ca2+-triggered vesicle fusion during membrane repair. Myoferlin regulates endocytosis, recycling of growth factor receptors and adhesion proteins, and is linked to the metastatic potential of cancer cells. Our previous studies establish that dysferlin is cleaved by calpains during membrane injury, with the cleavage motif encoded by alternately-spliced exon 40a. Herein we describe the cleavage of myoferlin, yielding a membrane-associated dual C2 domain 'mini-myoferlin'. Myoferlin bears two enzymatic cleavage sites: a canonical cleavage site encoded by exon 38 within the C2DE domain; and a second cleavage site in the linker adjacent to C2DE, encoded by alternately-spliced exon 38a, homologous to dysferlin exon 40a. Both myoferlin cleavage sites, when introduced into dysferlin, can functionally substitute for exon 40a to confer Ca2+-triggered calpain cleavage in response to membrane injury. However, enzymatic cleavage of myoferlin is complex, showing both constitutive or Ca2+-enhanced cleavage in different cell lines, that is not solely dependent on calpains-1 or -2. The functional impact of myoferlin cleavage was explored through signalling protein phospho-protein arrays revealing specific activation of ERK1/2 by ectopic expression of cleavable myoferlin, but not an uncleavable isoform. In summary, we molecularly define two enzymatic cleavage sites within myoferlin and demonstrate 'mini-myoferlin' can be detected in human breast cancer tumour samples and cell lines. These data further illustrate that enzymatic cleavage of ferlins is an evolutionarily preserved mechanism to release functionally specialized mini-modules.

High expression of myoferlin is associated with poor outcome in oropharyngeal squamous cell carcinoma patients and is inversely associated with HPV-status

Myoferlin (MYOF) is a member of ferlin family of membrane proteins that was originally discovered as a muscle specific protein. Recent studies have shown that myoferlin is also expressed in other cell types including endothelial cells and cancer cells. However, very little is known about the expression and biological role of myoferlin in head and neck cancer. In this study, we examined expression profile of myoferlin in oropharyngeal squamous cell carcinoma (OPSCC) and assessed its correlation with disease progression and patient outcome. In univariate analyses, nuclear MYOF was associated with poor overall survival (p<0.001) and these patients had 5.5 times increased hazard of death (95% Cl 3.4-8.8). Nuclear myoferlin expression was also directly associated with tumor recurrence (p<0.001), perineural invasion (p=0.008), extracapsular spread (p=0.009), higher T-stage (p=0.0015) and distant metastasis (p<0.001). In addition, nuclear MYOF expression was directly associated with IL-6 (p<0.001) and inversely with HPV status (p=0.0014). In a subgroup survival analysis, MYOF nuclear+/IL-6+ group had worst survival (84.6% mortality), whereas MYOF nuclear-/IL-6- had the best survival. Similarly, patients with HPV-negative/MYOF-positive tumors had worse survival compared to HPV-positive/MYOF-negative. Taken together, our results demonstrate for the first time that nuclear myoferlin expression independently predicts poor clinical outcome in OPSCC patients.