Transient Receptor Potential Vanilloid Type 1 (TRPV1) Expression Changes from Normal Urothelium to Transitional Cell Carcinoma of Human Bladder

Transient receptor potential vanilloid-1 (TRPV1) channels act as suppressors of the growth of glioma

The aim of this study was to investigate the expression and function of the transient receptor potential vanilloid 1 (TRPV1) in glioma. We found that the expression of TRPV1 mRNA and protein were upregulated in glioma compared with normal brain by qPCR and western blot analysis. In order to investigate the function of TRPV1 in glioma, short hairpin RNA (shRNA) and the inhibitor of TRPV1 were used. In vitro, the activation of TRPV1 induced cell apoptosis with decreased migration capability and inhibited proliferation, which was abolished upon TRPV1 pharmacological inhibition and silencing. Mechanistically, TRPV1 modulated glioma proliferation through the protein kinase B (Akt) signaling pathway. More importantly, in immunodeficient (NOD-SCID) mouse xenograft models, tumor size was significantly increased when TRPV1 expression was disrupted by a shRNA knockdown approach in vivo. Altogether, our findings indicate that TRPV1 negatively controls glioma cell proliferation in an Akt-dependent manner, which suggests that targeting TRPV1 may be a potential therapeutic strategy for glioma.

Cutaneous neurogenic inflammation mediated by TRPV1-NGF-TRKA pathway activation in rosacea is exacerbated by the presence of Demodex mites

BACKGROUND

Rosacea is a common chronic inflammatory skin condition that is often refractory to treatment, with frequent relapses. Alterations in the skin immunological response and Demodex mite infestation are the primary aetiologic factors targeted for treatment. Transient receptor potential cation channel subfamily V member 1 (TRPV1) is a nociceptive cation channel that plays a role in cutaneous neurogenic pain and can be activated by various rosacea triggers.

OBJECTIVES

We investigated the effects of TRPV1 modulation in rosacea, focussing on Demodex mite colonization and cutaneous neurogenic inflammation.

METHODS

We examined mRNA expression levels according to Demodex population counts. An in vitro study using capsazepine as a TRPV1 antagonist was performed to assess the influence of TRPV1 in keratinocytes. A rosacea-like mouse model was generated by the injection of the 37-amino acid C-terminal cathelicidin peptide (LL37), and changes in the skin, dorsal root ganglion (DRG) and ears were examined.

RESULTS

Increased Demodex mite population counts were associated with increased expression levels of TRPV1, tropomyosin receptor kinase A (TrkA) and nerve growth factor (NGF), and these levels could be reduced by capsazepine treatment in keratinocytes. In an in vivo study, the downstream effects of TRPV1 activation were investigated in the skin, DRG and ears of the rosacea-like mouse model.

CONCLUSIONS

The findings of this study are instrumental for understanding the underlying causes of rosacea and could potentially lead to the development of new treatments targeting the NGF-TrkA-TRPV1 pathway. The identification of this pathway as a therapeutic target could represent a major breakthrough for rosacea research, potentially resulting in more effective and targeted rosacea treatments. This study contributes to an improved understanding of rosacea pathophysiology, which may lead to the development of more effective treatments in the future.

"ThermoTRP" Channel Expression in Cancers: Implications for Diagnosis and Prognosis (Practical Approach by a Pathologist)

Temperature-sensitive transient receptor potential (TRP) channels (so-called "thermoTRPs") are multifunctional signaling molecules with important roles in cell growth and differentiation. Several "thermoTRP" channels show altered expression in cancers, though it is unclear if this is a cause or consequence of the disease. Regardless of the underlying pathology, this altered expression may potentially be used for cancer diagnosis and prognostication. "ThermoTRP" expression may distinguish between benign and malignant lesions. For example, TRPV1 is expressed in benign gastric mucosa, but is absent in gastric adenocarcinoma. TRPV1 is also expressed both in normal urothelia and non-invasive papillary urothelial carcinoma, but no TRPV1 expression has been seen in invasive urothelial carcinoma. "ThermoTRP" expression can also be used to predict clinical outcomes. For instance, in prostate cancer, TRPM8 expression predicts aggressive behavior with early metastatic disease. Furthermore, TRPV1 expression can dissect a subset of pulmonary adenocarcinoma patients with bad prognosis and resistance to a number of commonly used chemotherapeutic agents. This review will explore the current state of this rapidly evolving field with special emphasis on immunostains that can already be added to the armoire of diagnostic pathologists.

Thermo-Transient Receptor Potential Channels: Therapeutic Potential in Gastric Cancer

Over the last decade, researchers have found abnormal expression of transient receptor potential (TRP) channels. In particular, members of the thermally sensitive subclass (thermo-TRPs) are involved in many disease processes. Moreover, they have a vital role in the occurrence and development of gastric cancer (GC). Accordingly, thermo-TRPs constitute a major pharmacological target, and the elucidation of the mechanisms underlying their response to physiological stimuli or drugs is key for notable advances in GC treatment. Therefore, this paper summarizes the existing literature about thermo-TRP protein expression changes that are linked to the incidence and progression of GC. The review also discusses the implication of such association to pathology and cell physiology and identifies potential thermo-TRP protein targets for diagnosis and treatment of GC.

Optimized flow cytometric detection of transient receptor potential vanilloid-1 (TRPV1) in human hematological malignancies

The ectopic overexpression of transient receptor potential vanilloid-1 (TRPV1) has been detected in numerous solid cancers, including breast, prostate, pancreatic, and tongue epithelium cancer. However, the expression of TRPV1 in hematological malignancies remains unknown. Here we show through in silico analysis that elevated TRPV1 mRNA expression occurs in a range of hematological malignancies and presents an optimized flow cytometry method to rapidly assess TRPV1 protein expression for both cell lines and primary patient samples. Three anti-TRPV1 antibodies were evaluated for intracellular TRPV1 detection using flow cytometry resulting in an optimized protocol for the evaluation of TRPV1 in hematological malignant cell lines and patients' peripheral blood mononuclear cells (PBMC). Overexpression of TRPV1 was observed in THP-1 (acute monocytic leukemia) and U266B1 (multiple myeloma, MM), but not U937 (histiocytic lymphoma) compared to healthy PBMC. TRPV1 was also detected in all 49 patients including B-cell non-Hodgkin's lymphoma (B-NHL), MM, and others and 20 healthy controls. TRPV1 expression was increased in 8% of patients (MM = 2, B-NHL = 2). In conclusion, we provide an optimized flow cytometry method for routine expression analysis of clinical samples and show that TRPV1 is increased in a subset of patients with hematological malignancies.

The ion channel TRPV1 gain-of-function reprograms the immune microenvironment to facilitate colorectal tumorigenesis

Transient receptor potential vanilloid 1 (TRPV1) is a Ca²⁺-permeable ion channel that acts as cellular sensor and is implicated in the tumor microenvironment cross talk. However, the functional role of TRPV1 in colorectal cancer (CRC) is still controversial. By using a TRPV1 gain-of-function model, we previously reported that hyperfunctional TRPV1 exacerbated experimental colitis by modulating mucosal immunity. Here, we found that TRPV1 gain-of-function significantly promoted tumor initiation and progression in colitis-associated cancer, as evidenced by the increase in the number and size of tumor. Systemic TRPV1 hyperactivation fostered a tumor permissive microenvironment through altering macrophage activation status and shifting the Th1/Th2 balance towards Th2 phenotype. Mechanistically, TRPV1 gain-of-function directly potentiated M1 cytokine production in macrophage and enhanced Th2 immune response by promoting Calcineurin/nuclear factor of activated T cells (NFATc2) signaling activation. In patients with CRC, TRPV1 expression was increased in tumor immune infiltrating cells. TRPV1 level was associated with CRC progression and could impact clinical outcome. Our study reveals an important role for TRPV1 in regulating the immune microenvironment during colorectal tumorigenesis. TRPV1 might be a potential target for CRC immunotherapy.

TRP Channels Interactome as a Novel Therapeutic Target in Breast Cancer

Breast cancer is one of the most frequent cancer types worldwide and the first cause of cancer-related deaths in women. Although significant therapeutic advances have been achieved with drugs such as tamoxifen and trastuzumab, breast cancer still caused 627,000 deaths in 2018. Since cancer is a multifactorial disease, it has become necessary to develop new molecular therapies that can target several relevant cellular processes at once. Ion channels are versatile regulators of several physiological- and pathophysiological-related mechanisms, including cancer-relevant processes such as tumor progression, apoptosis inhibition, proliferation, migration, invasion, and chemoresistance. Ion channels are the main regulators of cellular functions, conducting ions selectively through a pore-forming structure located in the plasma membrane, protein–protein interactions one of their main regulatory mechanisms. Among the different ion channel families, the Transient Receptor Potential (TRP) family stands out in the context of breast cancer since several members have been proposed as prognostic markers in this pathology. However, only a few approaches exist to block their specific activity during tumoral progress. In this article, we describe several TRP channels that have been involved in breast cancer progress with a particular focus on their binding partners that have also been described as drivers of breast cancer progression. Here, we propose disrupting these interactions as attractive and potential new therapeutic targets for treating this neoplastic disease.

The Impact of TRPV1 on Cancer Pathogenesis and Therapy: A Systematic Review

The transient receptor potential cation channel subfamily V member 1 (TRPV1) is a transmembrane protein that can be activated by various physical and chemical stimuli and is associated with pain transduction. In recent years, TRPV1 was discovered to play essential roles in cancer tumorigenesis and development, as TRPV1 expression levels are altered in numerous cancer cell types. Several investigations have discovered direct associations between TRPV1 and cancer cell proliferation, cell death, and metastasis. Furthermore, about two dozen TRPV1 agonists/antagonists are under clinical trial, as TRPV1 is a potential drug target for treating various diseases. Hence, more researchers are focusing on the effects of TRPV1 agonists or antagonists on cancer tumorigenesis and development. However, both agonists and antagonists may reveal anti-cancer effects, and the effect may function via or be independent of TRPV1. In this review, we provide an overview of the impact of TRPV1 on cancer cell proliferation, cell death, and metastasis, as well as on cancer therapy and the tumor microenvironment, and consider the implications of using TRPV1 agonists and antagonists for future research and potential therapeutic approaches.

Transient receptor potential channels in sensory mechanisms of the lower urinary tract

Disruptions to sensory pathways in the lower urinary tract commonly occur and can give rise to lower urinary tract symptoms (LUTS). The unmet clinical need for treatment of LUTS has stimulated research into the molecular mechanisms that underlie neuronal control of the bladder and transient receptor potential (TRP) channels have emerged as key regulators of the sensory processes that regulate bladder function. TRP channels function as molecular sensors in urothelial cells and afferent nerve fibres and can be considered the origin of bladder sensations. TRP channels in the lower urinary tract contribute to the generation of normal and abnormal bladder sensations through a variety of mechanisms, and have demonstrated potential as targets for the treatment of LUTS in functional disorders of the lower urinary tract.

Cannabis-Derived Compounds Cannabichromene and Δ9-Tetrahydrocannabinol Interact and Exhibit Cytotoxic Activity against Urothelial Cell Carcinoma Correlated with Inhibition of Cell Migration and Cytoskeleton Organization

Cannabis sativa contains more than 500 constituents, yet the anticancer properties of the vast majority of cannabis compounds remains unknown. We aimed to identify cannabis compounds and their combinations presenting cytotoxicity against bladder urothelial carcinoma (UC), the most common urinary system cancer. An XTT assay was used to determine cytotoxic activity of C. sativa extracts on T24 and HBT-9 cell lines. Extract chemical content was identified by high-performance liquid chromatography (HPLC). Fluorescence-activated cell sorting (FACS) was used to determine apoptosis and cell cycle, using stained F-actin and nuclei. Scratch and transwell assays were used to determine cell migration and invasion, respectively. Gene expression was determined by quantitative Polymerase chain reaction (PCR). The most active decarboxylated extract fraction (F7) of high-cannabidiol (CBD) C. sativa was found to contain cannabichromene (CBC) and Δ9-tetrahydrocannabinol (THC). Synergistic interaction was demonstrated between CBC + THC whereas cannabinoid receptor (CB) type 1 and type 2 inverse agonists reduced cytotoxic activity. Treatments with CBC + THC or CBD led to cell cycle arrest and cell apoptosis. CBC + THC or CBD treatments inhibited cell migration and affected F-actin integrity. Identification of active plant ingredients (API) from cannabis that induce apoptosis and affect cell migration in UC cell lines forms a basis for pre-clinical trials for UC treatment.

Prognostic Significance of Transient Receptor Potential Vanilloid Type 1 (TRPV1) and Phosphatase and Tension Homolog (PTEN) in Epithelial Ovarian Cancer

BACKGROUND

Transient receptor potential vanilloid type 1 (TRPV1) has been studied in human malignancies, but has not been studied in epithelial ovarian cancer (EOC). We, therefore, investigated the significance of TRPV1 and correlation with phosphatase and tension homolog (PTEN) in EOC.

MATERIALS AND METHODS

Immunohistochemical analyses for TRPV1 and PTEN were performed using a tissue microarray. Moreover, the role of TRPV1 in cell growth was assessed in a EOC cell line.

RESULTS

High TRPV1 expression and the combination of high TRPV1 and low PTEN expression were an independent prognostic factor for overall survival and disease-free survival. In vitro results demonstrated that knockdown of TRPV1 was associated with decreased cell viability and colony formation.

CONCLUSION

There is a strong association between TRPV1 and PTEN and the combination of TRPV1 and PTEN is a strong indicator of prognostic predictor in EOC.

Ion Channel Signature in Healthy Pancreas and Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is the fourth most common cause of cancer-related deaths in United States and Europe. It is predicted that PDAC will become the second leading cause of cancer-related deaths during the next decades. The development of PDAC is not well understood, however, studies have shown that dysregulated exocrine pancreatic fluid secretion can contribute to pathologies of exocrine pancreas, including PDAC. The major roles of healthy exocrine pancreatic tissue are secretion of enzymes and bicarbonate rich fluid, where ion channels participate to fine-tune these biological processes. It is well known that ion channels located in the plasma membrane regulate multiple cellular functions and are involved in the communication between extracellular events and intracellular signaling pathways and can function as signal transducers themselves. Hereby, they contribute to maintain resting membrane potential, electrical signaling in excitable cells, and ion homeostasis. Despite their contribution to basic cellular processes, ion channels are also involved in the malignant transformation from a normal to a malignant phenotype. Aberrant expression and activity of ion channels have an impact on essentially all hallmarks of cancer defined as; uncontrolled proliferation, evasion of apoptosis, sustained angiogenesis and promotion of invasion and migration. Research indicates that certain ion channels are involved in the aberrant tumor growth and metastatic processes of PDAC. The purpose of this review is to summarize the important expression, localization, and function of ion channels in normal exocrine pancreatic tissue and how they are involved in PDAC progression and development. As ion channels are suggested to be potential targets of treatment they are furthermore suggested to be biomarkers of different cancers. Therefore, we describe the importance of ion channels in PDAC as markers of diagnosis and clinical factors.

pH-Channeling in Cancer: How pH-Dependence of Cation Channels Shapes Cancer Pathophysiology

Tissue acidosis plays a pivotal role in tumor progression: in particular, interstitial acidosis promotes tumor cell invasion, and is a major contributor to the dysregulation of tumor immunity and tumor stromal cells. The cell membrane and integral membrane proteins commonly act as important sensors and transducers of altered pH. Cell adhesion molecules and cation channels are prominent membrane proteins, the majority of which is regulated by protons. The pathophysiological consequences of proton-sensitive ion channel function in cancer, however, are scarcely considered in the literature. Thus, the main focus of this review is to highlight possible events in tumor progression and tumor immunity where the pH sensitivity of cation channels could be of great importance.

TRPV1 Antagonist DWP05195 Induces ER Stress-Dependent Apoptosis through the ROS-p38-CHOP Pathway in Human Ovarian Cancer Cells

In addition to their analgesic activity, transient receptor potential vanilloid 1 (TRPV1) agonists and antagonists demonstrate profound anti-cancer activities in various human cancers. In the present study, we investigated the anti-cancer activity of a novel TRPV1 antagonist, DWP05195, and evaluated its molecular mechanism in human ovarian cancer cells. DWP05195 demonstrated potent growth inhibitory effects in all five ovarian cancer cell lines examined. DWP05195 induced apoptosis through the activation of caspase-3, -8, and -9. DWP05195 induced C/EBP homologous protein (CHOP) expression and endoplasmic reticulum (ER) stress. Sodium phenylbutyrate (4-PBA), an ER-stress inhibitor, and CHOP knockdown significantly suppressed DWP5195-induced cell death. DWP05195-enhanced CHOP expression stimulated intrinsic and extrinsic apoptotic pathways through the regulation of Bcl2-like11 (BIM), death receptor 4 (DR4), and DR5. DWP05195-induced cell death was associated with increased reactive oxygen species (ROS) levels and p38 pathway activation. Pre-treatment with the antioxidant N-acetyl-L-cysteine (NAC) significantly suppressed DWP05195-induced CHOP expression and p38 activation. Inhibition of NADPH oxidase (NOX) through p47phox knockdown abolished DWP05195-induced CHOP expression and cell death. Taken together, the findings indicate that DWP05195 induces ER stress-induced apoptosis via the ROS-p38-CHOP pathway in human ovarian cancer cells.

The Combination of Transient Receptor Potential Vanilloid Type 1 (TRPV1) and Phosphatase and Tension Homolog (PTEN) is an Effective Prognostic Biomarker in Cervical Cancer

Transient receptor potential vanilloid type 1 (TRPV1) has been reported to play an important role in human cancers. However, the knowledge about TRPV1 in cervical cancer is sparse. Therefore, we evaluated the expression and clinical significance of TRPV1 in cervical cancer. Immunohistochemical analyses were performed for TRPV1 and phosphatase and tension homolog (PTEN) to delineate clinical significance using 150 cervical cancers, 230 cervical intraepithelial neoplasias, and 312 normal cervical epithelial tissues in a tissue microarray. Furthermore, the role of TRPV1 in cell growth was assessed in a cervical cancer cell line. The TRPV1 expression was significantly higher in cervical cancer tissues than in cervical intraepithelial neoplasias, and normal epithelial tissues (P<0.001). In cervical cancer tissues, TRPV1 expression negatively correlated with PTEN expression (Spearman ρ=-0.121, P=0.009). Multivariate survival analysis revealed high TRPV1 expression (hazard ratio=3.41, 95% confidence interval: 1.25-9.27, P=0.016) as an independent prognostic factor for overall survival. Notably. the high TRPV1/low PTEN expression showed the highest hazard ratio (5.87; 95% confidence interval: 2.18-15.82, P<0.001) for overall survival. In vitro results demonstrated that the overexpression of TRPV1 was associated with increased cell viability and colony formation. Overexpression of TRPV1 could be a good biomarker for the prediction of chemoradiation response. Our result suggested promising potential of high TRPV1/low PTEN as prognostic and survival makers. The possible link between the biologic function of TRPV1 and PTEN in cervical cancer warrants further studies.

Lipid Nanoparticle Inclusion Prevents Capsaicin-Induced TRPV1 Defunctionalization

BACKGROUND

Capsaicin (CPS) is a highly selective agonist of the transient receptor potential vanilloid type 1 (TRPV1) with a nanomolar affinity. High doses or prolonged exposure to CPS induces TRPV1 defunctionalization and, although this effect is currently used for the treatment of thermal hyperalgesia in chronic pain conditions, it is responsible of detrimental effects, such as denervation of sensory fibers. The aim of the present study was to formulate CPS loaded lipid nanocarriers (CPS-LN) in order to optimize CPS release, thus preventing TRPV1 internalization and degradation.

METHODS

CPS-LNs were formulated and characterized by in vitro studies. The activation of TRPV1 receptors after CPS-LN administration was evaluated by measuring spontaneous pain that was induced by local injection into the plantar surface of the mouse hind-paw. Moreover, the expression of TRPV1 in the skin was evaluated by western blot analysis in CPS-LN injected mice and then compared to a standard CPS solution (CPS-STD).

RESULTS

CPS inclusion in LN induced a lower pain response when compared to CPS-STD; further, it prevented TRPV1 down-regulation in the skin, while CPS-STD induced a significant reduction of TRPV1 expression.

CONCLUSIONS

Drug encapsulation in lipid nanoparticles produced an optimization of CPS release, thus reducing mice pain behavior and avoiding the effects that are caused by TRPV1 defunctionalization related to a prolonged activation of this receptor.

Transient receptor potential vanilloid 1 promotes EGFR ubiquitination and modulates EGFR/MAPK signalling in pancreatic cancer cells

Transient receptor potential vanilloid-1 (TRPV1) was first identified in sensory neurons, where it was suggested as a therapeutic target for pain relief. Here, we show that TRPV1 is expressed in the pancreatic cancer cell line, PANC-1; that epidermal growth factor receptor (EGFR) expression is downregulated by overexpression or agonist-induced activation of TRPV1; and conversely, that EGFR expression is increased after silencing TRPV1. Furthermore, TRPV1 overexpression inhibits cell proliferation and significantly reduces the mRNA levels of two oncogenes, KRAS and AKT2. More importantly, TRPV1 downregulates EGFR levels by inducing EGFR ubiquitination and degradation, which modulate EGFR/MAPK signalling in pancreatic cancer cells. These results illustrate the regulation and mechanism of TRPV1 on EGFR in pancreatic cancer cells and may provide new ideas for the design of novel antitumor drugs targeting EGFR. SIGNIFICANCE OF THE STUDY: We investigated the effect and mechanism of TRPV1 on EGFR-mediated proliferation and transformation of pancreatic cancer cells, with the aim of providing new ideas and experimental evidence for the application of strategies that promote EGFR degradation to treat pancreatic cancer.

Capsaicinoids: Multiple effects on angiogenesis, invasion and metastasis in human cancers

Cancer progression is a complex multistep process comprising of angiogenesis of the primary tumor, its invasion into the surrounding stroma and its migration to distant organs to produce metastases. Nutritional compounds of the "capsaicinoid" family regulate angiogenesis, invasion and metastasis of tumors. Capsaicinoids display robust anti-angiogenic activity in both cell culture and mice models. However, conflicting reports exist about the effect of capsaicinoids on invasion of metastasis of cancers. While some published reports have described an anti-invasive and anti-metastatic role for capsaicinoids, others have argued that capsaicinoids stimulate invasion and metastasis of cancers. The present review article summarizes these findings involving the bioactivity of capsaicin in angiogenesis, invasion and metastasis of cancer. A survey of literature indicate that they are several articles summarizing the growth-inhibitory activity of capsaicinoids but few describe its effects on angiogenesis, invasion and metastasis in detail. Our review article fills this gap of knowledge. The discovery of a second generation of natural and synthetic capsaicin analogs (with anti-tumor activity) will pave the way to improved strategies for the treatment of several human cancers.

Fibulin-5 contributes to colorectal cancer cell apoptosis via the ROS/MAPK and Akt signal pathways by downregulating transient receptor potential cation channel subfamily V member 1

Fibulin-5, a multifunctional extracellular matrix (ECM) protein, is secreted into the ECM, regulating metastasis and invasion in many malignant tumors. However, its role in colorectal cancer (CRC) has not been reported. In this study, we detected the expression of fibulin-5 in 56 CRC patients and eight CRC cell lines, revealing that fibulin-5 was expressed lower in CRC tumor tissues than in peritumor tissues. Furthermore, our study verified that fibulin-5 promoted cell apoptosis and reactive oxygen species (ROS) production by inhibiting transient receptor potential cation channel subfamily V member 1 (TRPV1) in CRC cells. Moreover, NAC (the scavenger of ROS), SB203580 (the inhibitor of p38), PD98059 (the inhibitor of ERK), and SC79 (the activator of Akt) were used to uncover that fibulin-5 induced apoptosis through the ROS/mitogen-activated protein kinase and Akt signal pathways by downregulating TRPV1. Together, these results suggest that fibulin-5 might serve as a novel drug target for the treatment of CRC patients.

Targeting Ca2+ signalling through phytomolecules to combat cancer

Cancer is amongst the life-threatening public health issue worldwide, hence responsible for millions of death every year. It is affecting human health regardless of their gender, age, eating habits, and ecological location. Many drugs and therapies are available for its cure still the need for effective targeted drugs and therapies are of paramount importance. In the recent past, Ca²⁺ signalling (including channels/transporters/pumps) are being studied as a plausible target for combating the cancer menace. Many evidence has shown that the intracellular Ca²⁺ homeostasis is altered in cancer cells and the remodelling is linked with tumor instigation, angiogenesis, progression, and metastasis. Focusing on these altered Ca²⁺ signalling tool kit for cancer treatment is a cross-cutting and emerging area of research. In addition, there are numerous phytomolecules which can be exploited as a potential Ca²⁺ (channels/transporters/ pumps) modulators in the context of targeting Ca²⁺ signalling in the cancer cell. In the present review, a list of plant-based potential Ca²⁺ (channel/transporters/pumps) modulators has been reported which could have application in the framework of repurposing the potential drugs to target Ca²⁺ signalling pathways in cancer cells. This review also aims to gain attention in and support for prospective research in this field.

TRPs in Tox: Involvement of Transient Receptor Potential-Channels in Chemical-Induced Organ Toxicity-A Structured Review

Chemicals can exhibit significant toxic properties. While for most compounds, unspecific cell damaging processes are assumed, a plethora of chemicals exhibit characteristic odors, suggesting a more specific interaction with the human body. During the last few years, G-protein-coupled receptors and especially chemosensory ion channels of the transient receptor potential family (TRP channels) were identified as defined targets for several chemicals. In some cases, TRP channels were suggested as being causal for toxicity. Therefore, these channels have moved into the spotlight of toxicological research. In this review, we screened available literature in PubMed that deals with the role of chemical-sensing TRP channels in specific organ systems. TRPA1, TRPM and TRPV channels were identified as essential chemosensors in the nervous system, the upper and lower airways, colon, pancreas, bladder, skin, the cardiovascular system, and the eyes. Regarding TRP channel subtypes, A1, M8, and V1 were found most frequently associated with toxicity. They are followed by V4, while other TRP channels (C1, C4, M5) are only less abundantly expressed in this context. Moreover, TRPA1, M8, V1 are co-expressed in most organs. This review summarizes organ-specific toxicological roles of TRP channels.

Decreased expression of TRPV1 in renal cell carcinoma: association with tumor Fuhrman grades and histopathological subtypes

Purpose

The aim of this study was to investigate whether the expression of the ligand-gated Ca²⁺ channel transient receptor potential vanilloid type-1 (TRPV1) in primary human renal cell carcinoma (RCC) is associated with clinicopathological features.

Patients and methods

Fresh and frozen primary tumor and normal peritumoral kidney tissues from 127 patients diagnosed with RCC were analyzed for TRPV1 expression by quantitative reverse transcription polymerase chain reaction (RT-PCR), Western blotting and immunohistochemistry.

Results

Quantitative RT-PCR revealed that TRPV1 was decreased 3.20-fold in RCC tissue vs normal peritumoral kidney tissue (p=0.012). Significantly different TRPV1 mRNA expression was detected in RCC tissues of different Fuhrman grades and histopathological subtypes (F=4.282, p=0.015 and F=5.205, p=0.014, respectively). Decreased TRPV1 expression was correlated with RCC histopathological subtype (R=-0.554, p=0.003) and Fuhrman grade (R=−0.525, p=0.006). Western blot analysis of TRPV1 protein expression showed similar results. Immunohistochemical analysis showed strong expression of TRPV1 in kidney tubules but demonstrated weak or no immunostaining in RCC tissues.

Conclusion

TRPV1 expression was decreased in RCC, which was significantly associated with tumor Fuhrman grades and histopathological subtypes. It seems to suggest that TRPV1 expression may be a valuable tool to predict the extent of RCC progression.

Cannabinoids Modulate Neuronal Activity and Cancer by CB1 and CB2 Receptor-Independent Mechanisms

Cannabinoids include the active constituents of Cannabis or are molecules that mimic the structure and/or function of these Cannabis-derived molecules. Cannabinoids produce many of their cellular and organ system effects by interacting with the well-characterized CB1 and CB2 receptors. However, it has become clear that not all effects of cannabinoid drugs are attributable to their interaction with CB1 and CB2 receptors. Evidence now demonstrates that cannabinoid agents produce effects by modulating activity of the entire array of cellular macromolecules targeted by other drug classes, including: other receptor types; ion channels; transporters; enzymes, and protein- and non-protein cellular structures. This review summarizes evidence for these interactions in the CNS and in cancer, and is organized according to the cellular targets involved. The CNS represents a well-studied area and cancer is emerging in terms of understanding mechanisms by which cannabinoids modulate their activity. Considering the CNS and cancer together allow identification of non-cannabinoid receptor targets that are shared and divergent in both systems. This comparative approach allows the identified targets to be compared and contrasted, suggesting potential new areas of investigation. It also provides insight into the diverse sources of efficacy employed by this interesting class of drugs. Obtaining a comprehensive understanding of the diverse mechanisms of cannabinoid action may lead to the design and development of therapeutic agents with greater efficacy and specificity for their cellular targets.

Expression and functionality of TRPV1 in breast cancer cells

Transient receptor potential (TRP) channels contribute to the regulation of intracellular calcium, which can promote cancer hallmarks in cases of dysregulation of gene transcription and calcium-dependent pro-proliferative or anti-apoptotic mechanisms. Several studies have begun to elucidate the roles of TRPV1, TRPV6, TRPM8, and TRPC1 in cancer progression; however, no study has examined the expression profiles of human TRP channels in breast cancer on a large scale. This study focused on the expression and functionality of TRPV1, a nonselective cation channel that was found to be expressed in different carcinoma tissues. Next-generation sequencing analyses revealed the expression of TRPV1 in several native breast cancer tissues, which was subsequently validated via reverse transcriptase-polymerase chain reaction. Activation of TRPV1 by its ligand capsaicin was associated with the growth inhibition of some cancer cell types; however, the signaling components involved are complex. In this study, stimulation by the TRPV1 agonist, capsaicin, of SUM149PT cells, a model system for the most aggressive breast cancer subtype, triple-negative breast cancer, led to intracellular calcium signals that were diminished by the specific TRPV1 antagonist, capsazepin. Activation of TRPV1 by capsaicin caused significant inhibition of cancer cell growth and induced apoptosis and necrosis. In conclusion, the current study revealed the expression profiles of human TRP channels in 60 different breast cancer tissues and cell lines and furthermore validated the antitumor activity of TRPV1 against SUM149PT breast cancer cells, indicating that activation of TRPV1 could be used as a therapeutic target, even in the most aggressive breast cancer types.

Gingerol Reverses the Cancer-Promoting Effect of Capsaicin by Increased TRPV1 Level in a Urethane-Induced Lung Carcinogenic Model

Both gingerol and capsaicin are agonists of TRPV1, which can negatively control tumor progression. This study observed the long-term effects of oral administration of 6-gingerol alone or in combination with capsaicin for 20 weeks in a urethane-induced lung carcinogenic model. We showed that lung carcinoma incidence and multiplicity were 70% and 21.2 ± 3.6, respectively, in the control versus 100% and 35.6 ± 5.2 in the capsaicin group (P < 0.01) and 50% and 10.8 ± 3.1 in the 6-gingerol group (P < 0.01). The combination of 6-gingerol and capsaicin reversed the cancer-promoting effect of capsaicin (carcinoma incidence of 100% versus 20% and multiplicity of 35.6 ± 5.2 versus 4.7 ± 2.3; P < 0.001). The cancer-promoting effect of capsaicin was due to increased epidermal growth-factor receptor (EGFR) level by decreased transient receptor potential vanilloid type-1 (TRPV1) level (P < 0.01) . The capsaicin-decreased EGFR level subsequently reduced levels of nuclear factor-κB (NF-κB) and cyclin D1 that favored enhanced lung epithelial proliferation and epithelial-mesenchymal transition (EMT) during lung carcinogenesis (P < 0.01). In contrast, 6-gingerol promoted TRPV1 level and drastically decreased the levels of EGFR, NF-κB, and cyclin D1 that favored reduced lung epithelial proliferation and EMT (P < 0.01). This study provides valuable information for the long-term consumption of chili-pepper-rich diets to decrease the risk of cancer development.

TRPV1 channel as a target for cancer therapy using CNT-based drug delivery systems

Carbon nanotubes are being considered for the design of drug delivery systems (DDSs) due to their capacity to internalize molecules and control their release. However, for cellular uptake of drugs, this approach requires an active translocation pathway or a channel to transport the drug into the cell. To address this issue, it is suggested to use TRPV1 ion channels as a potential target for drug release by nano-DDSs since these channels are overexpressed in cancer cells and allow the permeation of large cationic molecules. Considering these facts, this work presents three studies using molecular dynamics simulations of a human TRPV1 (hTRPV1) channel built here. The purpose of these simulations is to study the interaction between a single-wall carbon nanotube (SWCNT) and hTRPV1, and the diffusion of doxorubicin (DOX) across hTRPV1 and across a POPC lipid membrane. The first study shows an attractive potential between the SWCNT surface and hTRPV1, tilting the adsorbed SWCNT. The second study shows low diffusion probability of DOX across the open hTRPV1 due to a high free energy barrier. Although, the potential energy between DOX and hTRPV1 reveals an attractive interaction while DOX is inside hTRPV1. These results suggest that if the channel is dilated, then DOX diffusion could occur. The third study shows a lower free energy barrier for DOX across the lipid membrane than for DOX across hTRPV1. Taking into account the results obtained, it is feasible to design novel nano-DDSs based on SWCNTs to accomplish controlled drug release into cells using as translocation pathway, the hTRPV1 ion channel.

Role of TRP ion channels in cancer and tumorigenesis

Transient receptor potential (TRP) channels are recently identified proteins that form a versatile family of ion channels, the majority of which are calcium permeable and exhibit complex regulatory patterns with sensitivity to multiple environmental factors. While this sensitivity has captured early attention, leading to recognition of TRP channels as environmental and chemical sensors, many later studies concentrated on the regulation of intracellular calcium by TRP channels. Due to mutations, dysregulation of ion channel gating or expression levels, normal spatiotemporal patterns of local Ca(2+) distribution become distorted. This causes deregulation of downstream effectors sensitive to changes in Ca(2+) homeostasis that, in turn, promotes pathophysiological cancer hallmarks, such as enhanced survival, proliferation and invasion. These observations give rise to the appreciation of the important contributions that TRP channels make to many cellular processes controlling cell fate and positioning these channels as important players in cancer regulation. This review discusses the accumulated scientific knowledge focused on TRP channel involvement in regulation of cell fate in various transformed tissues.

Transient receptor potential channel C5 in cancer chemoresistance

The transient receptor potential (TRP) superfamily contains at least 28 homologs in mammalian. These proteins form TRP channels are permeable to monovalent and divalent cations and participate in a variety of physiological functions. Dysregulation of TRP channels is responsible for numerous diseases. This review provides a brief short overview of mammalian TRP channels with a focus on TRPC5 and its role in cancers. Dysregulation of TRPC5 interrupts Ca(2+) homeostasis in cancer cells, which activates signaling pathways that are highly associated with cancer progression, especially cancer chemoresistance. Based on the important role of TRPC5, we also discuss the potential of TRPC5 as a target for therapeutic intervention. Either direct targeting of TRPC5 or indirect interruption of TRPC5-related signaling pathways may effectively overcome cancer chemoresistance.

Capsaicin enhances anti-proliferation efficacy of pirarubicin via activating TRPV1 and inhibiting PCNA nuclear translocation in 5637 cells

The recurrence of bladder cancer after surgery with or without chemotherapy remains a major challenge in bladder cancer treatment. Previous studies have shown that transient receptor potential vanilloid 1 (TRPV1) acts as a tumor suppressor through inducing apoptosis in bladder cancer cells. However, whether activation of TRPV1 has any synergistic effects with pirarubicin (THP), one of main drugs used in urinary bladder instillation chemotherapy to improve chemotherapeutic efficacy has remained elusive. The present study verified that TRPV1 was differentially expressed in bladder cancer cell lines. Furthermore, activation of TRPV1 by capsaicin was shown to induce growth inhibition of 5637 cells in which TRPV1 was highly expressed, while the growth of T24 cells, which express TRPV1 at low levels, was not affected. In addition, the present study demonstrated that activation of TRPV1 enhanced the anti‑proliferative effects of pirarubicin using an MTT assay and cell cycle analysis. Finally, immunofluorescent microscopy revealed that activation of TRPV1 prevented the translocation of proliferating cell nuclear antigen to the nucleus. This phenomenon was reversed by pre‑treatment with capsazepine, a specific TRPV1 antagonist. In conclusion, the present study confirmed the anti‑tumor activity of TRPV1 against bladder cancer. Activation of TRPV1 may be applied as a novel strategy to treat bladder cancer or enhance the therapeutic efficacy of traditional chemotherapeutic drugs.

Acidosis and Formaldehyde Secretion as a Possible Pathway of Cancer Pain and Options for Improved Cancer Pain Control

The prevalence of cancer pain in patients with cancer is high. The majority of efforts are spent on research in cancer treatment, but only a small fraction focuses on cancer pain. Pain in cancer patients, viewed predominantly as a secondary issue, is considered to be due to the destruction of tissues, compression of the nerves, inflammation, and secretion of biological mediators from the necrotic tumor mass. As a result, opioid drugs have remained as the primary pharmacological therapy for cancer pain for the past hundred years. This report reviews evidence that cancer pain may be produced by the metabolic effects of two byproducts of cancer-high acidity in the cancer microenvironment and the secretion of formaldehyde and its metabolites. We propose the research and development of therapeutic approaches for preemptive, short- and long-term management of cancer pain using available drugs or nutraceutical agents that can suppress or neutralize lactic acid production in combination with formaldehyde scavengers. We believe this approach may not only improve cancer pain control but may also enhance the quality of life for patients.

TRPV1: A Potential Drug Target for Treating Various Diseases

Transient receptor potential vanilloid 1 (TRPV1) is an ion channel present on sensory neurons which is activated by heat, protons, capsaicin and a variety of endogenous lipids termed endovanilloids. As such, TRPV1 serves as a multimodal sensor of noxious stimuli which could trigger counteractive measures to avoid pain and injury. Activation of TRPV1 has been linked to chronic inflammatory pain conditions and peripheral neuropathy, as observed in diabetes. Expression of TRPV1 is also observed in non-neuronal sites such as the epithelium of bladder and lungs and in hair cells of the cochlea. At these sites, activation of TRPV1 has been implicated in the pathophysiology of diseases such as cystitis, asthma and hearing loss. Therefore, drugs which could modulate TRPV1 channel activity could be useful for the treatment of conditions ranging from chronic pain to hearing loss. This review describes the roles of TRPV1 in the normal physiology and pathophysiology of selected organs of the body and highlights how drugs targeting this channel could be important clinically.

Bladder cancer and urothelial impairment: the role of TRPV1 as potential drug target

Urothelium, in addition to its primary function of barrier, is now understood to act as a complex system of cell communication that exhibits specialized sensory properties in the regulation of physiological or pathological stimuli. Furthermore, it has been hypothesized that bladder inflammation and neoplastic cell growth, the two most representative pathological conditions of the lower urinary tract, may arise from a primary defective urothelial lining. Transient receptor potential vanilloid channel 1 (TRPV1), a receptor widely distributed in lower urinary tract structures and involved in the physiological micturition reflex, was described to have a pathophysiological role in inflammatory conditions and in the genesis and development of urothelial cancer. In our opinion new compounds, such as curcumin, the major component of turmeric Curcuma longa, reported to potentiate the effects of the chemotherapeutic agents used in the management of recurrent urothelial cancer in vitro and also identified as one of several compounds to own the vanillyl structure required to work like a TRPV1 agonist, could be thought as complementary in the clinical management of both the recurrences and the inflammatory effects caused by the endoscopic resection or intravesical chemotherapy administration or could be combined with adjuvant agents to potentiate their antitumoral effect.

Correlation between urothelial differentiation and sensory proteins P2X3, P2X5, TRPV1, and TRPV4 in normal urothelium and papillary carcinoma of human bladder

Terminal differentiation of urothelium is a prerequisite for blood-urine barrier formation and enables normal sensory function of the urinary bladder. In this study, urothelial differentiation of normal human urothelium and of low and high grade papillary urothelial carcinomas was correlated with the expression and localization of purinergic receptors (P2X3, and P2X5) and transient receptor potential vanilloid channels (TRPV1, and TRPV4). Western blotting and immunofluorescence of uroplakins together with scanning electron microscopy of urothelial apical surface demonstrated terminal differentiation of normal urothelium, partial differentiation of low grade carcinoma, and poor differentiation of high grade carcinoma. P2X3 was expressed in normal urothelium as well as in low grade carcinoma and in both cases immunolabeling was stronger in the superficial cells. P2X3 expression decreased in high grade carcinoma. P2X5 expression was detected in normal urothelium and in high grade carcinoma, while in low grade carcinoma its expression was diminished. The expression of TRPV1 decreased in low grade and even more in high grade carcinoma when compared with normal urothelium, while TRPV4 expression was unchanged in all samples. Our results suggest that sensory proteins P2X3 and TRPV1 are in correlation with urothelial differentiation, while P2X5 and TRPV4 have unique expression patterns.

Transient receptor potential vanilloid 4 (TRPV4) is downregulated in keratinocytes in human non-melanoma skin cancer

A subgroup of the transient receptor potential (TRP) channels, including vanilloid 1 (TRPV1), TRPV2, TRPV3, TRPV4, and TRP ankyrin 1 (TRPA1), is expressed in cutaneous peptidergic somatosensory neurons, and has been found in skin non-neuronal cells, such as keratinocytes. Different cancer cells express TRPs, where they may exert either pro- or antitumorigenic roles. Expression and function of TRPs in skin cancers have been, however, poorly investigated. Here, we have studied the distribution and expression of TRPs by immunohistochemistry and messenger RNA (mRNA) in human healthy skin and human keratinocytic tumors, including intraepidermal proliferative disorders (solar keratosis (SK) and Bowen's disease), and non-melanoma skin cancer (NMSC; basal cell and squamous cell carcinomas). Similar TRPV1, TRPV2, and TRPV3 staining was found in keratinocytes from healthy and tumor tissues. TRPA1 staining was increased solely in SK samples. However, the marked TRPV4 staining and TRPV4 mRNA expression, observed in healthy or inflamed skin, was abrogated both in premalignant lesions and NMSC. In a human keratinocyte cell line (HaCaT), TRPV4 stimulation released IL-8, which in turn downregulated TRPV4 expression. Selective reduction in TRPV4 expression could represent an early biomarker of skin carcinogenesis. Whether the cytokine-dependent, autocrine pathway that results in TRPV4 downregulation contributes to NMSC mechanism remains to be determined.

Vanilloids induce oral cancer apoptosis independent of TRPV1

OBJECTIVE

To investigate the mechanisms of vanilloid cytotoxicity and anti-tumor effects in oral squamous cell carcinoma (OSCC).

MATERIALS AND METHODS

Immunohistochemistry and qPCR analyses demonstrated expression of the TRP vanilloid type 1 (TRPV1) receptor in OSCC. Using cell proliferation assays, calcium imaging, and three mouse xenograft models, prototypical vanilloid agonist (capsaicin) and antagonist (capsazepine) were evaluated for cytotoxic and anti-tumor effects in OSCC.

RESULTS

OSCC cell lines treated with capsaicin displayed significantly reduced cell viability. Pre-treatment with capsazepine failed to reverse these effects. Moreover, capsazepine alone was significantly cytotoxic to tumor cells, suggesting the mechanism-of-action is independent of TRPV1 activation. This was further confirmed by calcium imaging indicating that TRPV1 channels are not functional in the cell lines tested. We then examined whether the observed vanilloid cytotoxicity was due to the generation of reactive oxygen species (ROS) and subsequent apoptosis. Induction of ROS was confirmed by flow cytometry and reversed by co-treatment with the antioxidant N-acetyl-cysteine (NAC). NAC also significantly reversed vanilloid cytotoxicity in cell proliferation assays. Dose-dependent induction of apoptosis with capsazepine treatment was demonstrated by FACS analyses and c-PARP expression in treated cells. Our in vivo xenograft studies showed that intra-tumoral injections of capsazepine exhibited high effectiveness in suppressing tumor growth with no identifiable toxicities.

CONCLUSIONS

These findings confirm TRPV1 channel expression in OSCC. However anti-tumor effects of vanilloids are independent of TRPV1 activation and are most likely due to ROS induction and subsequent apoptosis. Importantly, these studies demonstrate capsazepine is a potential therapeutic candidate for OSCC.

GAGs and GAGs diseases: when pathophysiology supports the clinic

The urinary epithelium has been the subject of considerable interest and much research in recent years. What has radically changed in the last decade is the concept of what the bladder epithelium really is. It is currently no longer considered just a simple barrier and a non-specific defence against infections, and it has been recognized as a specialized tissue regulating complex bladder functions and playing a fundamental and active role in the pathogenesis of cystitis. Researchers have been focussing on the receptors and mediators that are active in the sub-epithelial layer, with the hope that understanding the role of the urothelium defect will offer the opportunity for new therapeutic strategies. On the surface of the urothelial umbrella-cells there is a thick layer of glycoproteins and proteoglycans, which together are called Glycosaminoglycans (GAGs). They constitute a hydrophilic mucosal coating and act as a barrier against solutes found in urine. In recent years they have received special attention because injury to Gags, due to different noxae, has been identified as the first step in the genesis of chronic inflammatory bladder diseases, such as recurrent urinary tract infections, chemical or radiation cystitis, interstitial cystitis and/or Bladder Pain Syndrome. Aim of this study is to define the importance of the urothelium starting from the anatomy and physiology of the bladder wall. Furthermore, we will underline the role of glycosaminoglycans, focusing both on their pathophysiological role in the principal bladder diseases and on the therapeutic aspects from the clinical point of view.

Differential effects of intravesical resiniferatoxin on excitability of bladder spinal neurons upon colon-bladder cross-sensitization

Cross-sensitization in the pelvis may contribute to etiology of functional pelvic pain disorders such as interstitial cystitis/bladder pain syndrome (IC/BPS). Increasing evidence suggests the involvement of transient receptor potential vanilloid 1 (TRPV1) receptors in the development of neurogenic inflammation in the pelvis and pelvic organ cross-sensitization. The objective of this study was to test the hypothesis that desensitization of TRPV1 receptors in the urinary bladder can minimize the effects of cross-sensitization induced by experimental colitis on excitability of bladder spinal neurons. Extracellular activity of bladder neurons was recorded in response to graded urinary bladder distension (UBD) in rats pretreated with intravesical resiniferatoxin (RTX, 10(-7)M). Colonic inflammation was induced by intracolonic instillation of 2,4,6-trinitrobenzene sulfonic acid (TNBS). The duration of excitatory responses to noxious UBD during acute colonic inflammation (3 days post-TNBS) was significantly shortened in the group with RTX pretreatment (25.3±1.5s, n=49) when compared to the control group (35.1±4.2s, n=43, p<0.05). The duration of long-lasting excitatory responses, but not short-lasting responses of bladder spinal neurons during acute colitis was significantly reduced by RTX from 52.9±6.6s (n=21, vehicle group) to 34.4±2.1s (RTX group, n=21, p<0.05). However, activation of TRPV1 receptors in the urinary bladder prior to acute colitis increased the number of bladder neurons receiving input from large somatic fields from 22.7% to 58.2% (p<0.01). The results of our study provide evidence that intravesical RTX reduces the effects of viscerovisceral cross-talk induced by colonic inflammation on bladder spinal neurons. However, RTX enhances the responses of bladder neurons to somatic stimulation, thereby limiting its therapeutic potential.

Involvement of Transient Receptor Potential Melastatin 7 Channels in Sophorae Radix-induced Apoptosis in Cancer Cells: Sophorae Radix and TRPM7

Sophorae Radix (SR) plays a role in a number of physiologic and pharmacologic functions in many organs.

OBJECTIVE

The aim of this study was to clarify the potential role for transient receptor potential melastatin 7 (TRPM7) channels in SR-inhibited growth and survival of AGS and MCF-7 cells, the most common human gastric and breast adenocarcinoma cell lines.

METHODS

The AGS and the MCF-7 cells were treated with varying concentrations of SR. Analyses of the caspase-3 and - 9 activity, the mitochondrial depolarization and the poly (ADPribose) polymerase (PARP) cleavage were conducted to determine if AGS and MCF-7 cell death occured by apoptosis. TRPM7 channel blockers (Gd(3+) or 2-APB) and small interfering RNA (siRNA) were used in this study to confirm the role of TRPM7 channels. Furthermore, TRPM7 channels were overexpressed in human embryonic kidney (HEK) 293 cells to identify the role of TRPM7 channels in AGS and MCF-7 cell growth and survival.

RESULTS

The addition of SR to a culture medium inhibited AGS and MCF-7 cell growth and survival. Experimental results showed that the caspase-3 and -9 activity, the mitochondrial depolarization, and the degree of PARP cleavage was increased. TRPM7 channel blockade, either by Gd(3+) or 2-APB or by suppressing TRPM7 expression with small interfering RNA, blocked the SR-induced inhibition of cell growth and survival. Furthermore, TRPM7 channel overexpression in HEK 293 cells exacerbated SR-induced cell death.

CONCLUSIONS

These findings indicate that SR inhibits the growth and survival of gastric and breast cancer cells due to a blockade of the TRPM7 channel activity. Therefore, TRPM7 channels may play an important role in the survival of patients with gastric and breast cancer.

[TRP calcium channel and breast cancer: expression, role and correlation with clinical parameters]

Breast cancer (BC) has the highest incidence rate in women in industrialized countries. Statistically, it is estimated that one out of 10 women will develop BC during her life. Evidence is accumulating for the role of ion channels in the development of cancer. Most studied ion channels in BC are K(+) channels, which are involved in cell proliferation, cell cycle progression and cell migration, and Na(+) channels, which correlate with invasiveness. Emerging studies demonstrated the role of Ca(2+) signaling in cancer cell proliferation, survival and migration. Recent findings demonstrated that the expression and/or activity of the transient receptor potential (TRP) channels are altered in several cancers. Among the TRP families, TRPC (canonical or classical), TRPM (melastatin) and TRPV (vanilloid) are related to malignant growth and cancer progression. Although these channels are frequently and abundantly expressed in many tumors, their specific expression, activity and roles in BC are still poorly understood. The expression of TRP channels has also been proposed as a tool for diagnosis, prognosis and/or therapeutic issues of several diseases. In cancer, TRPV6 and TRPM8 have been proposed as tumor progression markers of prostate cancer outcome and TRPC6 as a novel therapeutic target for esophageal carcinoma. Interestingly high levels of TRPC3 expression correlate with a favorable prognosis in patients with lung adenocarcinoma. Our team has recently reported the expression and role of TRPC1, TRPC6, TRPM7, TRPM8 and TRPV6 in BC cell lines and primary cultures. We have also investigated TRP expression and their clinical significance in human breast adenocarcinoma and we suggest that TRP channels are new potential BC markers. Indeed TRPC1 and TRPM8 may be considered as good prognosis markers of well-differentiated tumors, TRPM7 as a proliferative marker of poorly differentiated tumors and TRPV6 as a prognosis marker of aggressive cancers. In this review, we summarize the data reported to date regarding the changes in TRP expression associated with BC. We also discuss the importance of TRP channels in BC cells proliferation and migration and their interest as new BC markers.

Capsaicin induces cycle arrest by inhibiting cyclin-dependent-kinase in bladder carcinoma cells

OBJECTIVE

Capsaicin is a specialized agonist of transient receptor potential vanilloid type 1 Ca2(+) channel, a member of the vanilloid receptor family of cation channels. We aimed to investigate the effects of capsaicin on the proliferation and cell death of human bladder cancer cells.

METHODS

Human bladder cancer cell line 5637 was cultured and the expression of transient receptor potential vanilloid type 1 verified by immunofluorescence and Western blot. Cells were given different disposals (different capsaicin concentration with/without pre-treating with capsazepine; capsazepine, acting as a competitive antagonist of capsaicin) to observe cell viability, cell cycle and cell death by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay and flow cytometry. The apoptosis indexes, such as intracellular production of reactive oxygen species and mitochondrial membrane potential were assessed to elucidate the potential mechanism of capsaicin effects in the cells.

RESULTS

Capsaicin decreased the viability of 5637 cells in a dose-dependent way. The flow cytometry outcome showed that capsaicin blocked the cell cycle in the G0/G1 period. The Western blot of cyclin-dependent-kinase involved in G1/S transfer verified this. Meanwhile, increased reactive oxygen species production and decreased mitochondrial membrane potential were detected in capsaicin-treated groups.

CONCLUSIONS

Capsaicin induces cell death through increased reactive oxygen species and decreased mitochondrial membrane potential. Furthermore, capsaicin inhibits the proliferation of 5637 bladder carcinoma cells by cycle arrest with the inhibition of CDK2, CDK4 and CDK6.

Antioncogenic effects of transient receptor potential vanilloid 1 in the progression of transitional urothelial cancer of human bladder

The progression of normal cells to a tumorigenic and metastatic state involves the accumulation of mutations in multiple key signaling proteins, encoded by oncogenes and tumor suppressor genes. Recently, members of the TRP channel family have been included in the oncogenic and tumor suppressor protein family. TRPM1, TRPM8, and TRPV6 are considered to be tumor suppressors and oncogenes in localized melanoma and prostate cancer, respectively. Herein, we focus our attention on the antioncogenic properties of TRPV1. Changes in TRPV1 expression occur during the development of transitional cell carcinoma (TCC) of human bladder. A progressive decrease in TRPV1 expression as the TCC stage increases triggers the development of a more aggressive gene phenotype and invasiveness. Finally, downregulation of TRPV1 represents a negative prognostic factor in TCC patients. The knowledge of the mechanism controlling TRPV1 expression might improve the diagnosis and new therapeutic strategies in bladder cancer.

Protons and Ca2+: ionic allies in tumor progression?

Ion channels and G-protein-coupled receptors (GPCRs) play a fundamental role in cancer progression by influencing Ca(2+) influx and signaling pathways in transformed cells. Transformed cells thrive in a hostile environment that is characterized by extracellular acidosis that promotes the pathological phenotype. The pathway(s) by which extracellular protons achieve this remain unclear. Here, a role for proton-sensing ion channels and GPCRs as mediators of the effects of extracellular protons in cancer cells is discussed.