Extracellular Electrophysiology in the Prostate Cancer Cell Model PC-3

Electrical excitability of cancer cells-CELEX model updated

The normal functioning of every cell in the body depends on its bioelectric properties and many diseases are caused by genetic and/or epigenetic dysregulation of the underlying ion channels. Metastasis, the main cause of death from cancer, is a complex multi-stage process in which cells break away from a primary tumour, invade the surrounding tissues, enter the circulation by encountering a blood vessel and spread around the body, ultimately lodging in distant organs and reproliferating to form secondary tumours leading to devastating organ failure. Such cellular behaviours are well known to involve ion channels. The CELEX model offers a novel insight to metastasis where it is the electrical excitation of the cancer cells that is responsible for their aggressive and invasive behaviour. In turn, the hyperexcitability is underpinned by concomitant upregulation of functional voltage-gated sodium channels and downregulation of voltage-gated potassium channels. Here, we update the in vitro and in vivo evidence in favour of the CELEX model for carcinomas. The results are unequivocal for the sodium channel. The potassium channel arm is also broadly supported by existing evidence although these data are complicated by the impact of the channels on the membrane potential and consequent secondary effects. Finally, consistent with the CELEX model, we show (i) that carcinomas are indeed electrically excitable and capable of generating action potentials and (ii) that combination of a sodium channel inhibitor and a potassium channel opener can produce a strong, additive anti-invasive effect. We discuss the possible clinical implications of the CELEX model in managing cancer.

The potential of marine-derived piperazine alkaloids: Sources, structures and bioactivities

Marine-derived piperazine alkaloids (MDPAs) constitute a significant group of natural compounds known for their diverse structures and biological activities. Over the past five decades, substantial efforts have been devoted to isolating these alkaloids from marine sources and characterizing their chemical and bioactive profiles. To date, a total of 922 marine-derived piperazine alkaloids have been reported from various marine organisms. These compounds demonstrate a wide range of pharmacological properties, including cytotoxicity, antibacterial, antifungal, antiviral, and various other activities. Notably, among these activities, cytotoxicity emerges as the most prominent characteristic of marine-derived piperazine alkaloids. This review also summarizes the structure-activity relationship (SAR) studies associated with the cytotoxicity of these compounds. In summary, our objective is to provide an overview of the research progress concerning marine-derived piperazine alkaloids, with the aim of fostering their continued development and utilization.

Blood pressure, calcium channel blockers, and the risk of prostate cancer: a Mendelian randomization study

BACKGROUND

Observational studies have found some evidence of an association between elevated blood pressure and prostate cancer risk; however, the results are inconclusive. We tested whether systolic blood pressure (SBP) influences prostate cancer risk and evaluated the effect of calcium channel blockers (CCB) on the disease using Mendelian randomization (MR) approach.

METHODS

We used 278 genetic variants associated with SBP and 16 genetic variants in CCB genes as instrumental variables. Effect estimates were obtained from the UK Biobank sample of 142,995 males and from PRACTICAL consortium (79,148 cases and 61,106 controls).

RESULTS

For each 10 mm Hg increase in SBP the estimated effect was OR 0.96 (0.90-1.01) for overall prostate cancer; and OR 0.92 (0.85-0.99) for aggressive prostate cancer. The MR-estimated effect of a 10 mm Hg- SBP lowering through CCB genetic variants was OR 1.22 (1.06-1.42) for all prostate cancers and OR 1.49 (1.18-1.89) for aggressive prostate cancer.

CONCLUSION

The results of our study did not support a causal relationship between SBP and prostate cancer; however, we found weak evidence of a protective effect of high SBP on aggressive prostate cancer and we found that blocking calcium channel receptors may increase prostate cancer risk.

RT-TRAQ: An algorithm for real-time tracking of faint quasi-periodic signals in noisy time series

We present an algorithm for live tracking of quasi-periodic faint signals in non-stationary, noisy, and phase-desynchronized time series measurements that commonly arise in embedded applications, such as wearable health monitoring. The first step of Rt-Traq is to continuously select fixed-length windows based on the rise or fall of data values in the stream. Subsequently, Rt-Traq calculates an averaged representative window, and its spectrum, whose frequency peaks reveal the underlying quasi-periodic signals. As each new data sample comes in, Rt-Traq incrementally updates the spectrum, to continuously track the signals through time. We develop several alternate implementations of the proposed algorithm. We evaluate their performance in tracking maternal and fetal heart rate using non-invasive photoplethysmography (PPG) data collected by a wearable device from animal experiments as well as a number of pregnant women who participated in our study. Our empirical results demonstrate improvements compared to competing approaches. We also analyze the memory requirement and complexity trade-offs between the implementations, which impact their demand on platform resources for real-time operation.

Voltage imaging reveals the dynamic electrical signatures of human breast cancer cells

Cancer cells feature a resting membrane potential (Vm) that is depolarized compared to normal cells, and express active ionic conductances, which factor directly in their pathophysiological behavior. Despite similarities to ‘excitable’ tissues, relatively little is known about cancer cell Vm dynamics. Here high-throughput, cellular-resolution Vm imaging reveals that Vm fluctuates dynamically in several breast cancer cell lines compared to non-cancerous MCF-10A cells. We characterize Vm fluctuations of hundreds of human triple-negative breast cancer MDA-MB-231 cells. By quantifying their Dynamic Electrical Signatures (DESs) through an unsupervised machine-learning protocol, we identify four classes ranging from "noisy” to “blinking/waving“. The Vm of MDA-MB-231 cells exhibits spontaneous, transient hyperpolarizations inhibited by the voltage-gated sodium channel blocker tetrodotoxin, and by calcium-activated potassium channel inhibitors apamin and iberiotoxin. The Vm of MCF-10A cells is comparatively static, but fluctuations increase following treatment with transforming growth factor-β1, a canonical inducer of the epithelial-to-mesenchymal transition. These data suggest that the ability to generate Vm fluctuations may be a property of hybrid epithelial-mesenchymal cells or those originated from luminal progenitors.

Harnessing the Membrane Potential to Combat Cancer Progression

Rapid fluctuations in the plasma membrane potential (Vm) provide the basis underlying the action potential waveform in electrically excitable cells; however, a growing body of literature shows that the Vm is also functionally instructive in nonexcitable cells, including cancer cells. Various ion channels play a key role in setting and fine tuning the Vm in cancer and stromal cells within the tumor microenvironment (TME), raising the possibility that the Vm could be targeted therapeutically using ion channel-modulating compounds. Emerging evidence points to the Vm as a viable therapeutic target, given its functional significance in regulating cell cycle progression, migration, invasion, immune infiltration, and pH regulation. Several compounds are now undergoing clinical trials and there is increasing interest in therapeutic manipulation of the Vm via application of pulsed electric fields. The purpose of this article is to update the reader on the significant recent and ongoing progress to elucidate the functional significance of Vm regulation in tumors, to highlight key remaining questions and the prospect of future therapeutic targeting. In particular, we focus on key developments in understanding the functional consequences of Vm alteration on tumor development via the activation of small GTPase (K-Ras and Rac1) signaling, as well as the impact of Vm changes within the heterogeneous TME on immune cell function and cancer progression.

SIRT5 Directly Inhibits the PI3K/AKT Pathway in Prostate Cancer Cell Lines

BACKGROUND/AIM

Prostate cancer (PCa) is the most commonly diagnosed genital cancer in men globally. Among patients who develop advanced PCa, 80% are affected by bone metastasis, with a sharp drop in survival rate. Despite efforts, the details of mechanisms of metastasis of PCa remain unclear. SIRT5, an NAD+-dependent deacylase, is hypothesized to be a crucial regulator of various cancers. The role of SIRT5 in cancer has not been extensively studied compared to other SIRTs. In this study, we showed significantly decreased levels of SIRT5 in PC-3M, a highly aggressive PC-3 cell variant.

MATERIALS AND METHODS

We characterized the differentially expressed proteins between parental and SIRT5 KO PC-3 cells using quantitative proteomics analysis.

RESULTS

A significant increase in expression of interleukin-1β (IL-1β) in SIRT5 KO cells was observed, and the PI3K/AKT/NF-ĸB signaling pathway was found significantly elevated in SIRT5 KO cells by the Gene Ontology annotation and KEGG pathway functional enrichment analysis. Moreover, we confirmed that SIRT5 can bind PI3K by immunoprecipitation analysis.

CONCLUSION

This study is the first to demonstrate a relationship between SIRT5 and PCa metastasis, suggesting that SIRT5-mediated inhibition of the PI3K/AKT/NK-kB pathway is reduced for secondary metastasis from bone to other tissues.

Electrotherapies for Glioblastoma

Non-thermal, intermediate frequency (100-500 kHz) electrotherapies present a unique therapeutic strategy to treat malignant neoplasms. Here, pulsed electric fields (PEFs) which induce reversible or irreversible electroporation (IRE) and tumour-treating fields (TTFs) are reviewed highlighting the foundations, advances, and considerations of each method when applied to glioblastoma (GBM). Several biological aspects of GBM that contribute to treatment complexity (heterogeneity, recurrence, resistance, and blood-brain barrier(BBB)) and electrophysiological traits which are suggested to promote glioma progression are described. Particularly, the biological responses at the cellular and molecular level to specific parameters of the electrical stimuli are discussed offering ways to compare these parameters despite the lack of a universally adopted physical description. Reviewing the literature, a disconnect is found between electrotherapy techniques and how they target the biological complexities of GBM that make treatment difficult in the first place. An attempt is made to bridge the interdisciplinary gap by mapping biological characteristics to different methods of electrotherapy, suggesting important future research topics and directions in both understanding and treating GBM. To the authors' knowledge, this is the first paper that attempts an in-tandem assessment of the biological effects of different aspects of intermediate frequency electrotherapy methods, thus offering possible strategies toward GBM treatment.

Microfluidics Integration into Low-Noise Multi-Electrode Arrays

Organ-on-Chip technology is commonly used as a tool to replace animal testing in drug development. Cells or tissues are cultured on a microchip to replicate organ-level functions, where measurements of the electrical activity can be taken to understand how the cell populations react to different drugs. Microfluidic structures are integrated in these devices to replicate more closely an in vivo microenvironment. Research has provided proof of principle that more accurate replications of the microenvironment result in better micro-physiological behaviour, which in turn results in a higher predictive power. This work shows a transition from a no-flow (static) multi-electrode array (MEA) to a continuous-flow (dynamic) MEA, assuring a continuous and homogeneous transfer of an electrolyte solution across the measurement chamber. The process through which the microfluidic system was designed, simulated, and fabricated is described, and electrical characterisation of the whole structure under static solution and a continuous flow rate of 80 µL/min was performed. The latter reveals minimal background disturbance, with a background noise below 30 µVpp for all flow rates and areas. This microfluidic MEA, therefore, opens new avenues for more accurate and long-term recordings in Organ-on-Chip systems.

In-Cell Nanoelectronics: Opening the Door to Intracellular Electrophysiology

Establishing a reliable electrophysiological recording platform is crucial for cardiology and neuroscience research. Noninvasive and label-free planar multitransistors and multielectrode arrays are conducive to perform the large-scale cellular electrical activity recordings, but the signal attenuation limits these extracellular devices to record subthreshold activities. In recent decade, in-cell nanoelectronics have been rapidly developed to open the door to intracellular electrophysiology. With the unique three-dimensional nanotopography and advanced penetration strategies, high-throughput and high-fidelity action potential like signal recordings is expected to be realized. This review summarizes in-cell nanoelectronics from versatile nano-biointerfaces, penetration strategies, active/passive nanodevices, systematically analyses the applications in electrogenic cells and especially evaluates the influence of nanodevices on the high-quality intracellular electrophysiological signals. Further, the opportunities, challenges and broad prospects of in-cell nanoelectronics are prospected, expecting to promote the development of in-cell electrophysiological platforms to meet the demand of theoretical investigation and clinical application.

Association Between the Overall Risk of Prostate Cancer and Use of Calcium Channel Blockers: A Systematic Review and Meta-analysis

PURPOSE

Although calcium channel blockers (CCBs) are now commonly prescribed to treat hypertension as a first-line drug therapy, their impact on prostate cancer (PCa) is unclear. This systematic review and meta-analysis was conducted to determine the association between CCB use and the overall risk of PCa.

METHODS

PubMed, EMBASE, and Cochrane were searched up to December 26, 2019, stratified according to statistical method of outcome [odd ratios (ORs), relative ratios (RRs), hazard ratios (HRs)] and cumulative duration of CCB use. The quality assessment of included studies was evaluated by using the Newcastle-Ottawa Scale. Fixed effects models were used to study the association between CCB use and the risk of PCa. Between-study heterogeneity was quantified by using Cochran's Q-statistic and I² statistics. Sensitivity analysis was performed by excluding the studies one by one, and publication bias was analyzed by using funnel plots.

FINDINGS

Nineteen studies with 1,418,407 patients were identified for inclusion in the meta-analysis, which was based on the comparison of cohort studies, nested case-control studies, and case-control studies. Pooled estimates showed a RR of 1.08 (95% CI, 1.05-1.11; P < 0.00001) and a HR of 1.07 (95% CI, 1.02-1.13; P = 0.008) for association between CCB use and the risk of PCa. In addition, the results of subgroup analysis showed that CCB users of <5 years had an 8% increased overall risk of PCa (RR, 1.08; 95% CI, 1.04-1.12; P = 0.0001), and CCB users of 5-10 years had a 13% increased overall risk of PCa (RR, 1.13; 95% CI, 1.04-1.23; P = 0.003).

IMPLICATIONS

CCB use had a tendency to increase the overall risk of PCa, and cumulative duration of CCB use might also be positively correlated with the overall risk of PCa.

Progress in the Knowledge, Application and Influence of Extremely Low Frequency Signals

This paper describes the characteristics of contributions made by researchers worldwide in the field of ELF (extremely low frequency) waves from 1957 to 2019. The data were collected through the Scopus database and processed with analytical and bibliometric techniques. The selection of the keywords is an essential step, because ELF has a very different meaning in some areas of medicine, where it is associated with a gene. A total of 12,436 documents were worked on in 12 thematic communities according to their collaborative relationships between authors and documents. Studies included authors publishing in the different thematic areas and the country where the USA stands first with more researchers in this theme than China and Japan. Documents were analyzed from the temporal perspective, their overall contribution, means of publication, and the language of the publication. Research requires extra effort and multidisciplinary collaboration to improve the knowledge, the application, and influence of these fields.

Human Breast Cancer Cells Demonstrate Electrical Excitability

Breast cancer is one of the most prevalent types of cancers worldwide and yet, its pathophysiology is poorly understood. Single-cell electrophysiological studies have provided evidence that membrane depolarization is implicated in the proliferation and metastasis of breast cancer. However, metastatic breast cancer cells are highly dynamic microscopic systems with complexities beyond a single-cell level. There is an urgent need for electrophysiological studies and technologies capable of decoding the intercellular signaling pathways and networks that control proliferation and metastasis, particularly at a population level. Hence, we present for the first time non-invasive in vitro electrical recordings of strongly metastatic MDA-MB-231 and weakly/non-metastatic MCF-7 breast cancer cell lines. To accomplish this, we fabricated an ultra-low noise sensor that exploits large-area electrodes, of 2 mm², which maximizes the double-layer capacitance and concomitant detection sensitivity. We show that the current recorded after adherence of the cells is dominated by the opening of voltage-gated sodium channels (VGSCs), confirmed by application of the highly specific inhibitor, tetrodotoxin (TTX). The electrical activity of MDA-MB-231 cells surpasses that of the MCF-7 cells, suggesting a link between the cells’ bioelectricity and invasiveness. We also recorded an activity pattern with characteristics similar to that of Random Telegraph Signal (RTS) noise. RTS patterns were less frequent than the asynchronous VGSC signals. The RTS noise power spectral density showed a Lorentzian shape, which revealed the presence of a low-frequency signal across MDA-MB-231 cell populations with propagation speeds of the same order as those reported for intercellular Ca²⁺ waves. Our recording platform paves the way for real-time investigations of the bioelectricity of cancer cells, their ionic/pharmacological properties and relationship to metastatic potential.

In Vivo Evidence for Voltage-Gated Sodium Channel Expression in Carcinomas and Potentiation of Metastasis

A wide body of evidence suggests that voltage-gated sodium channels (VGSCs) are expressed de novo in several human carcinomas where channel activity promotes a variety of cellular behaviours integral to the metastatic cascade. These include directional motility (including galvanotaxis), pH balance, extracellular proteolysis, and invasion. Contrary to the substantial in vitro data, however, evidence for VGSC involvement in the cancer process in vivo is limited. Here, we critically assess, for the first time, the available in vivo evidence, hierarchically from mRNA level to emerging clinical aspects, including protein-level studies, electrolyte content, animal tests, and clinical imaging. The evidence strongly suggests that different VGSC subtypes (mainly Nav1.5 and Nav1.7) are expressed de novo in human carcinoma tissues and generally parallel the situation in vitro. Consistent with this, tissue electrolyte (sodium) levels, quantified by clinical imaging, are significantly higher in cancer vs. matched non-cancer tissues. These are early events in the acquisition of metastatic potential by the cancer cells. Taken together, the multi-faceted evidence suggests that the VGSC expression has clinical (diagnostic and therapeutic) potential as a prognostic marker, as well as an anti-metastatic target. The distinct advantages offered by the VGSC include especially (1) its embryonic nature, demonstrated most clearly for the predominant neonatal Nav1.5 expression in breast and colon cancer, and (2) the specifically druggable persistent current that VGSCs develop under hypoxic conditions, as in growing tumours, which promotes invasiveness and metastasis.

Ultrasensitive System for Electrophysiology of Cancer Cell Populations: A Review

Bioelectricity is the electrical activity produced by living organisms. Understanding the role of bioelectricity in a disease context is important as it contributes to both disease diagnosis and therapeutic intervention. Electrophysiology tools work well for neuronal cultures; however, they are limited in their ability to detect the electrical activity of non-neuronal cells, wherein the majority of cancers arise. Electronic structures capable of detecting and modulating signaling, in real-time, in electrically quiescent cells are urgently required. One of the limitations to understanding the role of bioelectricity in cancer is the inability to detect low-level signals. In this study, we review our latest advances in devising bidirectional transducers with large electrode areas and concomitant low impedances. The resulting high sensitivity is demonstrated by the extracellular detection of electrical activity in Rat-C6 glioma and prostate cancer (PC-3) cell populations. By using specific inhibitors, we further demonstrated that the large electrical activity in Rat-C6 glioma populations is acidosis driven. For PC-3 cells, the use of a calcium inhibitor together with the slowly varying nature of the signal suggests that Ca²⁺ channels are involved in the cohort electrogenicity.