Overexpression of short TRPM8 variant α promotes cell migration and invasion, and decreases starvation-induced apoptosis in prostate cancer LNCaP cells

Roles of TRPM channels in glioma

Gliomas are the most common type of primary brain tumor. Despite advances in treatment, it remains one of the most aggressive and deadly tumor of the central nervous system (CNS). Gliomas are characterized by high malignancy, heterogeneity, invasiveness, and high resistance to radiotherapy and chemotherapy. It is urgent to find potential new molecular targets for glioma. The TRPM channels consist of TRPM1-TPRM8 and play a role in many cellular functions, including proliferation, migration, invasion, angiogenesis, etc. More and more studies have shown that TRPM channels can be used as new therapeutic targets for glioma. In this review, we first introduce the structure, activation patterns, and physiological functions of TRPM channels. Additionally, the pathological mechanism of glioma mediated by TRPM2, 3, 7, and 8 and the related signaling pathways are described. Finally, we discuss the therapeutic potential of targeting TRPM for glioma.

Intracellular Ca2+ signalling: unexpected new roles for the usual suspect

Cytosolic Ca2+ signals are organized in complex spatial and temporal patterns that underlie their unique ability to regulate multiple cellular functions. Changes in intracellular Ca2+ concentration ([Ca2+]i) are finely tuned by the concerted interaction of membrane receptors and ion channels that introduce Ca2+ into the cytosol, Ca2+-dependent sensors and effectors that translate the elevation in [Ca2+]i into a biological output, and Ca2+-clearing mechanisms that return the [Ca2+]i to pre-stimulation levels and prevent cytotoxic Ca2+ overload. The assortment of the Ca2+ handling machinery varies among different cell types to generate intracellular Ca2+ signals that are selectively tailored to subserve specific functions. The advent of novel high-speed, 2D and 3D time-lapse imaging techniques, single-wavelength and genetic Ca2+ indicators, as well as the development of novel genetic engineering tools to manipulate single cells and whole animals, has shed novel light on the regulation of cellular activity by the Ca2+ handling machinery. A symposium organized within the framework of the 72nd Annual Meeting of the Italian Society of Physiology, held in Bari on 14-16th September 2022, has recently addressed many of the unexpected mechanisms whereby intracellular Ca2+ signalling regulates cellular fate in healthy and disease states. Herein, we present a report of this symposium, in which the following emerging topics were discussed: 1) Regulation of water reabsorption in the kidney by lysosomal Ca2+ release through Transient Receptor Potential Mucolipin 1 (TRPML1); 2) Endoplasmic reticulum-to-mitochondria Ca2+ transfer in Alzheimer's disease-related astroglial dysfunction; 3) The non-canonical role of TRP Melastatin 8 (TRPM8) as a Rap1A inhibitor in the definition of some cancer hallmarks; and 4) Non-genetic optical stimulation of Ca2+ signals in the cardiovascular system.

On the modulation of TRPM channels: Current perspectives and anticancer therapeutic implications

The transient melastatin receptor potential (TRPM) ion channel subfamily functions as cellular sensors and transducers of critical biological signal pathways by regulating ion homeostasis. Some members of TRPM have been cloned from cancerous tissues, and their abnormal expressions in various solid malignancies have been correlated with cancer cell growth, survival, or death. Recent evidence also highlights the mechanisms underlying the role of TRPMs in tumor epithelial-mesenchymal transition (EMT), autophagy, and cancer metabolic reprogramming. These implications support TRPM channels as potential molecular targets and their modulation as an innovative therapeutic approach against cancer. Here, we discuss the general characteristics of the different TRPMs, focusing on current knowledge about the connection between TRPM channels and critical features of cancer. We also cover TRPM modulators used as pharmaceutical tools in biological trials and an indication of the only clinical trial with a TRPM modulator about cancer. To conclude, the authors describe the prospects for TRPM channels in oncology.

Therapeutic potential of TRPM8 channels in cancer treatment

Cancer is a multifactorial process associated with changes in signaling pathways leading to cell cycle variations and gene expression. The transient receptor potential melastatin 8 (TRPM8) channel is a non-selective cation channel expressed in neuronal and non-neuronal tissues, where it is involved in several processes, including thermosensation, differentiation, and migration. Cancer is a multifactorial process associated with changes in signaling pathways leading to variations in cell cycle and gene expression. Interestingly, it has been shown that TRPM8 channels also participate in physiological processes related to cancer, such as proliferation, survival, and invasion. For instance, TRPM8 channels have an important role in the diagnosis, prognosis, and treatment of prostate cancer. In addition, it has been reported that TRPM8 channels are involved in the progress of pancreatic, breast, bladder, colon, gastric, and skin cancers, glioblastoma, and neuroblastoma. In this review, we summarize the current knowledge on the role of TRPM8 channels in cancer progression. We also discuss the therapeutic potential of TRPM8 in carcinogenesis, which has been proposed as a molecular target for cancer therapy.

AMPK's double-faced role in advanced stages of prostate cancer

Prostate cancer (PCa) is the second leading cause of cancer deaths in men. Unfortunately, a very limited number of drugs are available for the relapsed and advanced stages of PCa, adding only a few months to survival; therefore, it is vital to develop new drugs. 5´ AMP-activated protein kinase (AMPK) is a master regulator of cell metabolism. It plays a significant role in the metabolism of PCa; hence, it can serve well as a treatment option for the advanced stages of PCa. However, whether this pathway contributes to cancer cell survival or death remains unknown. The present study reviews the possible pathways by which AMPK plays role in the advanced stages of PCa, drug resistance, and metastasis: (1) AMPK has a contradictory role in promoting glycolysis and the Warburg effect which are correlated with cancer stem cells (CSCs) survival and advanced PCa. It exerts its effect by interacting with hypoxia-induced factor 1 (HIF1) α, pyruvate kinase 2 (PKM2), glucose transporter (GLUT) 1 and pyruvate dehydrogenase complex (PDHC), which are key regulators of glycolysis; however, whether it promotes or discourage glycolysis is not conclusive. It can also exert an anti-CSC effect by negative regulation of NANOG and epithelial-mesenchymal transition (EMT) transcription factors, which are the major drivers of CSC maintenance; (2) the regulatory effect of AMPK on autophagy is also noticeable. Androgen receptors' expression increases AMPK activation through Calcium/calmodulin-dependent protein kinase 2 (CaMKK2) and induces autophagy. In addition, AMPK itself increases autophagy by downregulating the mammalian target of rapamycin complex (mTORC). However, whether increased autophagy inhibits or promotes cell death and drug resistance is contradictory. This study reveals that there are numerous pathways other than cell metabolism by which AMPK exerts its effects in the advanced stages of PCa, making it a priceless treatment target. Finally, we mention some drugs developed to treat the advanced stages of PCa by acting on AMPK.

TRPM8 as an Anti-Tumoral Target in Prostate Cancer Growth and Metastasis Dissemination

In the fight against prostate cancer (PCa), TRPM8 is one of the most promising clinical targets. Indeed, several studies have highlighted that TRPM8 involvement is key in PCa progression because of its impact on cell proliferation, viability, and migration. However, data from the literature are somewhat contradictory regarding the precise role of TRPM8 in prostatic carcinogenesis and are mostly based on in vitro studies. The purpose of this study was to clarify the role played by TRPM8 in PCa progression. We used a prostate orthotopic xenograft mouse model to show that TRPM8 overexpression dramatically limited tumor growth and metastasis dissemination in vivo. Mechanistically, our in vitro data revealed that TRPM8 inhibited tumor growth by affecting the cell proliferation and clonogenic properties of PCa cells. Moreover, TRPM8 impacted metastatic dissemination mainly by impairing cytoskeleton dynamics and focal adhesion formation through the inhibition of the Cdc42, Rac1, ERK, and FAK pathways. Lastly, we proved the in vivo efficiency of a new tool based on lipid nanocapsules containing WS12 in limiting the TRPM8-positive cells' dissemination at metastatic sites. Our work strongly supports the protective role of TRPM8 on PCa progression, providing new insights into the potential application of TRPM8 as a therapeutic target in PCa treatment.

Integrated Analysis of a Competing Endogenous RNA Network Reveals a Prognostic lncRNA Signature in Bladder Cancer

Long non-coding RNAs (lncRNAs) act as competing endogenous RNAs (ceRNAs) to regulate mRNA expression through sponging microRNA in tumorigenesis and progression. However, following the discovery of new RNA interaction, the differentially expressed RNAs and ceRNA regulatory network are required to update. Our study comprehensively analyzed the differentially expressed RNA and corresponding ceRNA network and thus constructed a potentially predictive tool for prognosis. “DESeq2” was used to perform differential expression analysis. Two hundred and six differentially expressed (DE) lncRNAs, 222 DE miRNAs, and 2,463 DE mRNAs were found in this study. The lncRNA-mRNA interactions in the miRcode database and the miRNA-mRNA interactions in the starBase, miRcode, and mirTarBase databases were searched, and a competing endogenous RNA (ceRNA) network with 186 nodes and 836 interactions was subsequently constructed. Aberrant expression patterns of lncRNA NR2F1-AS1 and lncRNA AC010168.2 were evaluated in two datasets (GSE89006, GSE31684), and real-time polymerase chain reaction was also performed to validate the expression pattern. Furthermore, we found that these two lncRNAs were independent prognostic biomarkers to generate a prognostic lncRNA signature by univariate and multivariate Cox analyses. According to the lncRNA signature, patients in the high-risk group were associated with a poor prognosis and validated by an external dataset. A novel genomic-clinicopathologic nomogram to improve prognosis prediction of bladder cancer was further plotted and calibrated. Our study deepens the understanding of the regulatory ceRNA network and provides an easy-to-do genomic-clinicopathological nomogram to predict the prognosis in patients with bladder cancer.

TRPM8 Inhibition Regulates the Proliferation, Migration and ROS Metabolism of Bladder Cancer Cells

Introduction

Based on accumulating evidence, transient receptor potential (TRP) ion channels may play important roles in the occurrence and the progression of cancer. TRP melastatin 8 (TRPM8), a member of the TRP family, functions as a Ca²⁺-permeable channel and regulates various physiological and pathological processes. However, the effects of TRPM8 on bladder cancer (BCa) and its underlying mechanisms have not been elucidated.

Methods

BCa tissues and matched noncancerous tissues were collected to examine the expression of the TRPM8 mRNA and protein using qRT-PCR, Western blotting and immunofluorescence staining. Meanwhile, the effect of knockdown or inhibition of the activity of the TRPM8 protein on the proliferation, migration and ROS metabolism of bladder cancer cells was detected using the MTT assay, clonogenic survival assay, Transwell chamber migration assay, and reactive oxygen species (ROS) detection, respectively. Furthermore, a mouse model transplanted with BCa cells was established to assess tumor growth after TRPM8 expression was inhibited in vivo.

Results

Compared with the noncancerous tissues, the levels of TRPM8 in BCa tissues were significantly increased. Knockdown or inhibition of the activity of the TRPM8 protein in BCa cells reduced cell proliferation and migration. Moreover, the production of ROS was increased in cells treated with siTRPM8, which was accompanied by increased levels of Catalase, HO-1 and SOD2. Furthermore, a mouse model transplanted with the stable TRPM8-deficient T24 cell line was established, demonstrating that knockdown of TRPM8 delayed tumor growth in vivo.

Discussion

TRPM8 might play an essential for BCa tumor progression and metastasis by interfering with BCa cell proliferation, motility, ROS metabolism and migration.

TRPV4 Overexpression Promotes Metastasis Through Epithelial-Mesenchymal Transition in Gastric Cancer and Correlates with Poor Prognosis

Purpose

Transient receptor potential vanilloid 4 (TRPV4) has been reported to be involved in the progression of several human tumors. Nevertheless, clinical significance and molecular mechanism of TRPV4 in gastric cancer (GC) remain poorly defined.

Patients and Methods

Immunohistochemistry assays were used to investigate the correlation between the expression of TRPV4 and epithelial–mesenchymal transition (EMT) markers in human GC tissues. The correlations between TRPV4 expression and clinicopathological features and between TRPV4 expression and survival rates were also examined. TRPV4 knockdown was performed by using small interfering RNAs. In vitro, Cell Counting Kit-8 (CCK-8) assay, colony formation assay, and transwell assay were employed to further explore the biological functions of TRPV4, and Western blotting was used to evaluate the changes in the expression of TRPV4 protein and EMT-related proteins in HGC-27 and MGC-803 human GC cell lines.

Results

TRPV4 expression was upregulated in GC tissues and cell lines. TRPV4 overexpression was associated with greater depth of tumor invasion, lymph node metastasis, higher TNM stage, poor overall survival, and worse disease-free survival. TRPV4 expression was inversely correlated with E-cadherin expression and positively correlated with vimentin expression. In vitro, knockdown of TRPV4 inhibited GC cell proliferation, colony formation, and invasion. Furthermore, the knockdown of TRPV4 modulated EMT by upregulating E-cadherin expression and downregulating the expression of N-cadherin and vimentin. In addition, the EMT-related transcription factor Snail was downregulated, whereas the expression levels of other transcription factors such as Slug and Twist did not change.

Conclusion

TRPV4 was upregulated in human GC and the overexpression of TRPV4 could promote GC progression, partially through Snail-mediated EMT.

Evaluation of the TRPM protein family as potential biomarkers for various types of human cancer using public database analyses

The Transient Receptor Potential Melastatin (TRPM) protein family members have been demonstrated to be involved in a variety of different types of human cancer. However, to the best of our knowledge, there has not yet been a systematic study regarding the mRNA expression of the TRPM protein family or its prognostic value in human cancer. The present study investigated TRPM expression and its prognostic value in various human cancer types via the Oncomine database, Kaplan-Meier plotter, and the PrognoScan and Gene Expression Profiling Interactive Analysis databases. It was revealed that the transcriptional levels of TRPM1, TRPM3 and TRPM6 were decreased in the majority of cancer tissues, while TRPM2 was increased in most cancer types. In addition, the high or low transcriptional levels of the TRPM protein family members were associated with survival outcomes of different types of solid tumors. The present study suggested that certain TRPM protein family members may serve as useful biomarkers for cancer prognosis and anticancer targets for cancer treatment.

Exploring the Therapeutic Potential of Membrane Transport Proteins: Focus on Cancer and Chemoresistance

Improving the therapeutic efficacy of conventional anticancer drugs represents the best hope for cancer treatment. However, the shortage of druggable targets and the increasing development of anticancer drug resistance remain significant problems. Recently, membrane transport proteins have emerged as novel therapeutic targets for cancer treatment. These proteins are essential for a plethora of cell functions ranging from cell homeostasis to clinical drug toxicity. Furthermore, their association with carcinogenesis and chemoresistance has opened new vistas for pharmacology-based cancer research. This review provides a comprehensive update of our current knowledge on the functional expression profile of membrane transport proteins in cancer and chemoresistant tumours that may form the basis for new cancer treatment strategies.

UBASH3B Is a Novel Prognostic Biomarker and Correlated With Immune Infiltrates in Prostate Cancer

Background: UBASH3B (STS1) is an important gene that negatively regulates T-cell receptor signaling in activated T-lymphocytes that involved in cancers. However, the function of UBASH3B in prostate cancer (PCa) and the correlation between UBASH3B and tumor-infiltrating immune cells still remain unclear.

Methods: Real-time PCR and immunohistochemistry were applied to detect mRNA and protein expression of UBASH3B in PCa patients and benign prostate hyperplasia patients (BPH). Clinical features of patients with PCa were recorded and Kaplan Meier curve was subsequently plotted. Based on mRNA expression of UBASH3B, patients with PCa from TCGA database were divided into low-UBASH3B-expression group and high-UBASH3B-expression group for construct lncRNA-miRNA-mRNA network and analyzing GO and KEGG pathways. Single gene analysis method was performed by using GSEA to interpret gene expression data in PCa. The PPI network was constructed using STRING and the correlation between UBASH3B and tumor-infiltrating immune cells was analyzed by TIMER and CIBERSORT.

Results: The mRNA and protein expression of UBASH3B were upregulated in PCa. The abundant expression of UBASH3B is associated with poor prognosis in PCa. The subnetwork of UBASH3B contains three lncRNAs (MIAT, LINC01297, MYLK-AS1) and four miRNAs (hsa-miR-200a-3p, hsa-miR-455-5p, hsa-miR-192-5p, hsamiR- 215-5P). The mRNA expression of UBASH3B was involved in 28 KEGG pathways. GSEA analysis showed that 18 hallmark gene sets were significantly enriched in high-UBASH3B-expression, whereas 1 gene set was enriched in low-UBASH3B-expression. PPI network revealed a tightly interaction between UBASH3B and LCP2 (an immune related gene). TIMER and CIBERSORT database indicated that UBASH3B was correlated with 11 types of tumor-infiltrating immune cells (naïve B cell, memory B cells, resting CD4⁺ memory T cell, activated CD4⁺ memory T cell, regulatory T cell, activated NK cell, M2 macrophages, resting dendritic cells, activated dendritic cells, resting mast cells, neutrophils).

Conclusions: In conclusion, UBASH3B may be a novel potential prognostic biomarker and is associated with tumor-infiltrating immune cells in tumor microenvironment, suggesting UBASH3B as a potential target for future treatment of PCa.

Ca2+ Channel Toolkit in Neuroendocrine Tumors

Neuroendocrine tumors (NET) constitute a heterogeneous group of malignancies with various clinical presentations and growth rates but a common origin in neuroendocrine cells located all over the body. NET are a relatively low-frequency disease mostly represented by gastroenteropancreatic (GEP) and bronchopulmonary tumors (pNET); on the other hand, an increasing frequency and prevalence have been associated with NET. Despite great efforts in recent years, the management of NET is still a critical unmet need due to the lack of knowledge of the biology of the disease, the lack of adequate biomarkers, late presentation, the relative insensitivity of imaging modalities, and a paucity of predictably effective treatment options. In this context Ca2+ signals, being pivotal molecular devices in sensing and integrating signals from the microenvironment, are emerging to be particularly relevant in cancer, where they mediate interactions between tumor cells and the tumor microenvironment to drive different aspects of neoplastic progression (e.g., cell proliferation and survival, cell invasiveness, and proangiogenetic programs). Indeed, ion channels represent good potential pharmacological targets due to their location on the plasma membrane, where they can be easily accessed by drugs. The present review aims to provide a critical and up-to-date overview of NET development integrating Ca2+ signal involvement. In this perspective, we first give an introduction to NET and Ca2+ channels and then describe the different families of Ca2+ channels implicated in NET, i.e., ionotropic receptors, voltage-dependent Ca2+ channels, and transient receptor potential channels, as well as intracellular Ca2+ channels and their signaling molecules.

The oncogenic roles of TRPM ion channels in cancer

Transient receptor potential (TRP) proteins are a diverse family of ion channels present in multiple types of tissues. They function as gatekeepers for responses to sensory stimuli including temperature, vision, taste, and pain through their activities in conducting ion fluxes. The TRPM (melastatin) subfamily consists of eight members (i.e., TRPM1-8), which collectively regulate fluxes of various types of cations such as K⁺ , Na⁺ , Ca²⁺ , and Mg²⁺ . Growing evidence in the past two decades indicates that TRPM ion channels, their isoforms, or long noncoding RNAs encoded within the locus may be oncogenes involved in the regulation of cancer cell growth, proliferation, autophagy, invasion, and epithelial-mesenchymal transition, and their significant association with poor clinical outcomes of cancer patients. In this review, we describe and discuss recent findings implicating TRPM channels in different malignancies, their functions, mechanisms, and signaling pathways involved in cancers, as well as summarizing their normal physiological functions and the availability of ion channel pharmacological inhibitors.

The Homeobox gene, HOXB13, Regulates a Mitotic Protein-Kinase Interaction Network in Metastatic Prostate Cancers

HOXB13, a homeodomain transcription factor, is linked to recurrence following radical prostatectomy. While HOXB13 regulates Androgen Receptor (AR) functions in a context dependent manner, its critical effectors in prostate cancer (PC) metastasis remain largely unknown. To identify HOXB13 transcriptional targets in metastatic PCs, we performed integrative bioinformatics analysis of differentially expressed genes (DEGs) in the proximity of the human prostate tumor-specific AR binding sites. Unsupervised Principal Component Analysis (PCA) led to a focused core HOXB13 target gene-set referred to as HOTPAM9 (HOXB13 Targets separating Primary And Metastatic PCs). HOTPAM9 comprised 7 mitotic kinase genes overexpressed in metastatic PCs, TRPM8, and the heat shock protein HSPB8, whose levels were significantly lower in metastatic PCs compared to the primary disease. The expression of a two-gene set, CIT and HSPB8 with an overall balanced accuracy of 98.8% and a threshold value of 0.2347, was sufficient to classify metastasis. HSPB8 mRNA expression was significantly increased following HOXB13 depletion in multiple metastatic CRPC models. Increased expression of HSPB8 by the microtubule inhibitor Colchicine or by exogenous means suppressed migration of mCRPC cells. Collectively, our results indicate that HOXB13 promotes metastasis of PCs by coordinated regulation of mitotic kinases and blockade of a putative tumor suppressor gene.

Comparative RNA-seq analysis reveals dys-regulation of major canonical pathways in ERG-inducible LNCaP cell progression model of prostate cancer

Prostate Cancer (CaP) is the second leading cause of cancer related death in USA. In human CaP, gene fusion between androgen responsive regulatory elements at the 5'-untranslated region of TMPRSS2 and ETS-related genes (ERG) is present in at least 50% of prostate tumors. Here we have investigated the unique cellular transcriptome associated with over-expression of ERG in ERG-inducible LNCaP cell model system of human CaP. Comprehensive transcriptome analyses reveal a distinct signature that distinguishes ERG dependent and independent CaP in LNCaP cells. Our data highlight a significant heterogeneity among the transcripts. Out of the 526 statistically significant differentially expressed genes, 232 genes are up-regulated and 294 genes are down-regulated in response to ERG. These ERG-associated genes are linked to several major cellular pathways, cell cycle regulation being the most significant. Consistently our data indicate that ERG plays a key role in modulating the expression of genes required for G1 to S phase transition, particularly those that affect cell cycle arrest at G1 phase. Moreover, cell cycle arrest in response to ERG appears to be promoted by induction of p21 in a p53 independent manner. These findings may provide new insights into mechanisms that promote growth and progression of CaP.

Evolution of the human cold/menthol receptor, TRPM8

Genes showing versatile functions or subjected to fast expansion and contraction during the adaptation of species to specific ecological conditions, like sensory receptors for odors, pheromones and tastes, are characterized by a great plasticity through evolution. One of the most fascinating sensory receptors in the family of TRP channels, the cold and menthol receptor TRPM8, has received significant attention in the literature. Recent studies have reported the existence of TRPM8 channel isoforms encoded by alternative mRNAs transcribed from alternative promoters and processed by alternative splicing. Since the first draft of the human genome was accomplished in 2000, alternative transcription, alternative splicing and alternative translation have appeared as major sources of gene product diversity and are thought to participate in the generation of complexity in higher organisms. In this study, we investigate whether alternative transcription has been a driving force in the evolution of the human forms of the cold receptor TRPM8. We identified 33 TRPM8 alternative mRNAs (24 new sequences) and their associated protein isoforms in human tissues. Using comparative genomics, we described the evolution of the human TRPM8 sequences in eight ancestors since the origin of Amniota, and estimated in which ancestors the new TRPM8 variants originated. In order to validate the estimated origins of this receptor, we performed experimental validations of predicted exons in mouse tissues. Our results suggest a first diversification event of the cold receptor in the Boreoeutheria ancestor, and a subsequent divergence at the origin of Simiiformes.

ADP-Ribose and oxidative stress activate TRPM8 channel in prostate cancer and kidney cells

Activation of TRPM8 channel through oxidative stress may induce Ca²⁺ and pro-apoptotic signals in prostate cancer and kidney cells. The aim of this study was to evaluate activation of TRPM8 can increase apoptosis and oxidative stress in the prostate cancer (Du145^M8), TRPM8 knock out (Du 145^M8KO), transfected (HEK293^TM8) and non-transfected human kidney (HEK293) cells. Intracellular Ca²⁺ responses to TRPM8 activation were increased in the Du145^M8 and HEK293^TM8 cells from coming cumene hydrogen peroxide (CHPx), menthol, ADP-Ribose (ADPR), but not in the HEK293 and Du 145^M8KO cells. The intracellular Ca²⁺ responses to both ADPR and CHPx were totally inhibited by the thiol cycle antioxidant glutathione, and TRPM8 blockers (N-(p-amylcinnamoyl)anthranilic acid and capsazepine). Apoptosis, Annexin V, mitochondrial membrane depolarization, intracellular ROS, caspase 3 and 9 values were increased through TRPM8 activation in the Du 145^M8 but not in the Du 145^M8KO and non-transfected HEK293 cells by CHPx and hydrogen peroxide. In conclusion, apoptotic and oxidant effects on the cells were increased activation of TRPM8 by oxidative stress and ADPR. Activation of TRPM8 through oxidative stress and ADPR in the cells could be used as an effective strategy in the treatment of prostate cancer cells.

TRPM8 and prostate: a cold case?

While originally cloned from the prostate in 2001, transient receptor potential, melastatin member 8 (TRPM8) has since been identified as the cold/menthol receptor in the peripheral nervous system. This discovery has led to hundreds of studies regarding the role of this channel in pain and thermosensation phenomena, while relegating TRPM8 involvement in cancer to a secondary role. Despite these findings, there is growing evidence that TRPM8 should be carefully studied within the frame of carcinogenesis, especially in the prostate, where it is highly expressed and where many teams have confirmed variations in its expression during cancer progression. Its regulation by physiological factors, such as PSA and androgens, has proved that TRPM8 can exhibit an activity beyond that of a cold receptor, thus explaining how the channel can be activated in organs not exposed to temperature variations. With this review, we aim to provide a brief overview of the current knowledge regarding the complex roles of TRPM8 in prostate carcinogenesis and to show that this research path still represents a "hot" topic with potential clinical applications in the short term.

Alternative Splicing Detection Tool-a novel PERL algorithm for sensitive detection of splicing events, based on next-generation sequencing data analysis

Next-generation sequencing (NGS) can provide researchers with high impact information regarding alternative splice variants or transcript identifications. However, the enormous amount of data acquired from NGS platforms make the analysis of alternative splicing events hard to accomplish. For this reason, we designed the "Alternative Splicing Detection Tool" (ASDT), an algorithm that is capable of identifying alternative splicing events, including novel ones from high-throughput NGS data. ASDT is available as a PERL script at http://aias.biol.uoa.gr/~mtheo and can be executed on any system with PERL installed. In addition to the detection of annotated and novel alternative splicing events from high-throughput NGS data, ASDT can also analyze the intronic regions of genes, thus enabling the detection of novel cryptic exons residing in annotated introns, extensions of previously annotated exons, or even intron retentions. Consequently, ASDT demonstrates many innovative and unique features that can efficiently contribute to alternative splicing analysis of NGS data.

RNA interference-mediated depletion of TRPM8 enhances the efficacy of epirubicin chemotherapy in prostate cancer LNCaP and PC3 cells

Several studies have shown that transient receptor potential cation channel subfamily M member 8 (TRPM8), which has been regarded as a novel prostate-specific marker, serves a key role in processes such as the proliferation, viability and cell migration of prostate cancer cells. Efforts have been made to uncover the potential role of targeting TRPM8 in the management of prostate cancer; it has been verified that TRPM8-targeted blockade, either by RNA interference-mediated depletion or specific TRPM8 inhibitors, could reduce the rate of proliferation and proliferative fraction, and induce apoptosis in prostate cancer cells. The aim of the present study was to investigate the effect of knockdown of TRPM8 on chemosensitivity in prostate cancer LNCaP and PC3 cells. The RNA interference-mediated depletion of TRPM8 inhibited proliferation and enhanced epirubicin chemosensitivity of LNCaP and PC3 cells, and promoted epirubicin-induced apoptosis by increasing the phosphorylation of p38 mitogen-activated protein kinase (hereafter p38) and c-Jun N-terminal kinase (JNK)/mitogen-activated protein kinase signaling pathways, which was demonstrated via the use of specific inhibitors of phosphorylation of p38 and JNK. The results demonstrate that the targeted silencing of TRPM8 expression is a therapeutic strategy for treatment of prostate cancer that has considerable potential, even for castration-resistant prostate cancer.

Overexpression of p54nrb/NONO induces differential EPHA6 splicing and contributes to castration-resistant prostate cancer growth

The non-POU domain-containing octamer binding protein p54^nrb/NONO is a multifunctional nuclear protein involved in RNA splicing, processing, and transcriptional regulation of nuclear hormone receptors. Through chromosome copy number analysis via whole-exome sequencing, we revealed amplification of the chromosome Xq11.22-q21.33 locus containing the androgen receptor (AR) and NONO genes in androgen-independent, castration-resistant prostate cancer (CRPC)-like LNCaP-SF cells. Moreover, NONO was frequently amplified and overexpressed in patients with CRPC. RNA sequencing data revealed that a truncated ephrin type-A receptor 6 (EPHA6) splice variant (EPHA6-001) was overexpressed in LNCaP-SF cells, and knockdown of NONO or EPHA6-001 prevented EPHA6-001 expression and reduced proliferation and invasion by LNCaP-SF cells grown under androgen deprivation conditions. Growth inhibition and differential splicing of EPHA6 mRNA by p54^nrb/NONO were confirmed in gene silencing experiments in 22Rv1 PCa cells. Importantly, NONO knockdown in LNCaP-SF cells led to reduced tumor growth in castrated mice. These findings indicate that p54^nrb/NONO is amplified and overexpressed in CRPC cells and clinical samples, and facilitates CRPC growth by mediating aberrant EPHA6 splicing. We therefore propose that p54^nrb/NONO constitutes a novel and attractive therapeutic target for CRPC.

TRPV4 plays a role in breast cancer cell migration via Ca2+-dependent activation of AKT and downregulation of E-cadherin cell cortex protein

TRPV4 belongs to the 'Transient Receptor Potential' (TRP) superfamily. It has been identified to profoundly affect a variety of physiological processes, including nociception, heat sensation and inflammation. Unlike other TRP superfamily channels, its role in cancers are unknown until recently when we reported TRPV4 to be required for cancer cell softness that may promote breast cancer cell extravasation and metastasis. Here, we elucidated the molecular mechanisms mediated by TRPV4 in the metastatic breast cancer cells. TRPV4-mediated signaling was demonstrated to involve Ca²⁺-dependent activation of AKT and downregulation of E-cadherin expression, which was abolished upon TRPV4 silencing. Functionally, TRPV4-enhanced breast caner cell transendothelial migration requires AKT activity while a combination of transcriptional and post-translational regulation contributed to the TRPV4-mediated E-cadherin downregulation. Finally, mass spectrometry analysis revealed that TRPV4 is required for the expression of a network of secreted proteins involved in extracellular matrix remodeling. In conclusion, TRPV4 may regulate breast cancer metastasis by regulating cell softness through the Ca²⁺-dependent AKT-E-cadherin signaling axis and regulation of the expression of extracellular proteins.

Molecular mechanisms of tumour invasion: regulation by calcium signals

Intracellular calcium (Ca²⁺ ) signals are key regulators of multiple cellular functions, both healthy and physiopathological. It is therefore unsurprising that several cancers present a strong Ca²⁺ homeostasis deregulation. Among the various hallmarks of cancer disease, a particular role is played by metastasis, which has a critical impact on cancer patients' outcome. Importantly, Ca²⁺ signalling has been reported to control multiple aspects of the adaptive metastatic cancer cell behaviour, including epithelial-mesenchymal transition, cell migration, local invasion and induction of angiogenesis (see Abstract Figure). In this context Ca²⁺ signalling is considered to be a substantial intracellular tool that regulates the dynamicity and complexity of the metastatic cascade. In the present study we review the spatial and temporal organization of Ca²⁺ fluxes, as well as the molecular mechanisms involved in metastasis, analysing the key steps which regulate initial tumour spread.

Differential Impacts of Alternative Splicing Networks on Apoptosis

Apoptosis functions as a common mechanism to eliminate unnecessary or damaged cells during cell renewal and tissue development in multicellular organisms. More than 200 proteins constitute complex networks involved in apoptotic regulation. Imbalanced expressions of apoptosis-related factors frequently lead to malignant diseases. The biological functions of several apoptotic factors are manipulated through alternative splicing mechanisms which expand gene diversity by generating discrete variants from one messenger RNA precursor. It is widely observed that alternatively-spliced variants encoded from apoptosis-related genes exhibit differential effects on apoptotic regulation. Alternative splicing events are meticulously regulated by the interplay between trans-splicing factors and cis-responsive elements surrounding the regulated exons. The major focus of this review is to highlight recent studies that illustrate the influences of alternative splicing networks on apoptotic regulation which participates in diverse cellular processes and diseases.

TRPM8 Puts the Chill on Prostate Cancer

Prostate cancer (PCa) is one of the most frequently diagnosed cancers in developed countries. Several studies suggest that variations in calcium homeostasis are involved in carcinogenesis. Interestingly, (Transient Receptor Potential Melastatin member 8) TRPM8 calcium permeable channel expression is differentially regulated during prostate carcinogenesis, thereby suggesting a potential functional role for this channel in those cell processes, which are important for PCa evolution. Indeed, several studies have shown that TRPM8 plays a key role in processes such as the proliferation, viability and cell migration of PCa cells. Where cell migration is concerned, TRPM8 seems to have a protective anti-invasive effect and could be a particularly promising therapeutic target. The goal of this review is to inventory advances in understanding of the role of TRPM8 in the installation and progression of PCa.