1
|
Buchanan PJ, McCloskey KD. Ca V channels and cancer: canonical functions indicate benefits of repurposed drugs as cancer therapeutics. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2016; 45:621-633. [PMID: 27342111 PMCID: PMC5045480 DOI: 10.1007/s00249-016-1144-z] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 05/17/2016] [Accepted: 05/23/2016] [Indexed: 01/19/2023]
Abstract
The importance of ion channels in the hallmarks of many cancers is increasingly recognised. This article reviews current knowledge of the expression of members of the voltage-gated calcium channel family (CaV) in cancer at the gene and protein level and discusses their potential functional roles. The ten members of the CaV channel family are classified according to expression of their pore-forming α-subunit; moreover, co-expression of accessory α2δ, β and γ confers a spectrum of biophysical characteristics including voltage dependence of activation and inactivation, current amplitude and activation/inactivation kinetics. CaV channels have traditionally been studied in excitable cells including neurones, smooth muscle, skeletal muscle and cardiac cells, and drugs targeting the channels are used in the treatment of hypertension and epilepsy. There is emerging evidence that several CaV channels are differentially expressed in cancer cells compared to their normal counterparts. Interestingly, a number of CaV channels also have non-canonical functions and are involved in transcriptional regulation of the expression of other proteins including potassium channels. Pharmacological studies show that CaV canonical function contributes to the fundamental biology of proliferation, cell-cycle progression and apoptosis. This raises the intriguing possibility that calcium channel blockers, approved for the treatment of other conditions, could be repurposed to treat particular cancers. Further research will reveal the full extent of both the canonical and non-canonical functions of CaV channels in cancer and whether calcium channel blockers are beneficial in cancer treatment.
Collapse
Affiliation(s)
- Paul J Buchanan
- Centre for Cancer Research and Cell Biology, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast, Northern Ireland, BT9 7AE, UK.,National Institute of Cellular Biotechnology, School of Nursing and Human Science, Dublin City University, Glasnevin, Dublin 9, Ireland
| | - Karen D McCloskey
- Centre for Cancer Research and Cell Biology, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast, Northern Ireland, BT9 7AE, UK.
| |
Collapse
|
2
|
Cheng X, Pachuau J, Blaskova E, Asuncion-Chin M, Liu J, Dopico AM, Jaggar JH. Alternative splicing of Cav1.2 channel exons in smooth muscle cells of resistance-size arteries generates currents with unique electrophysiological properties. Am J Physiol Heart Circ Physiol 2009; 297:H680-8. [PMID: 19502562 DOI: 10.1152/ajpheart.00109.2009] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Voltage-dependent calcium (Ca(2+), Ca(V)1.2) channels are the primary Ca(2+) entry pathway in smooth muscle cells of resistance-size (myogenic) arteries, but their molecular identity remains unclear. Here we identified and quantified Ca(V)1.2 alpha(1)-subunit splice variation in myocytes of rat resistance-size (100-200 microm diameter) cerebral arteries. Full-length clones containing either exon 1b or the recently identified exon 1c exhibited additional primary splice variation at exons 9*, 21/22, 31/32, and +/- 33. Real-time PCR confirmed the findings from full-length clones and indicated that the major Ca(V)1.2 variant contained exons 1c, 8, 21, and 32+33, with approximately 57% containing 9*. Exon 9* was more prevalent in clones containing 1c (72%) than in those containing 1b (33%), suggesting exon-selective combinatorial splicing. To examine the functional significance of this splicing profile, membrane currents produced by each of the four exon 1b/c/ +/- 9* variants were characterized following transfection in HEK293 cells. Exon 1c and 9* caused similar hyperpolarizing shifts in both current-voltage relationships and voltage-dependent activation of currents. Furthermore, exon 9* induced a hyperpolarizing shift only in the voltage-dependent activation of channels containing exon 1b, but not in those containing exon 1c. In contrast, exon 1b, 1c, or +9* did not alter voltage-dependent inactivation. In summary, we have identified the Ca(V)1.2 alpha(1)-subunit splice variant population that is expressed in myocytes of resistance-size arteries and the unique electrophysiological properties of recombinant channels formed by exon 1 and 9* variation. The predominance of exon 1c and 9* in smooth muscle cell Ca(V)1.2 channels causes a hyperpolarizing shift in the voltage sensitivity of currents toward the physiological arterial voltage range.
Collapse
Affiliation(s)
- Xiaoyang Cheng
- Department of Physiology , University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA
| | | | | | | | | | | | | |
Collapse
|
3
|
Tang ZZ, Liao P, Li G, Jiang FL, Yu D, Hong X, Yong TF, Tan G, Lu S, Wang J, Soong TW. Differential splicing patterns of L-Type calcium channel Cav1.2 subunit in hearts of Spontaneously Hypertensive Rats and Wistar Kyoto rats. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:118-30. [DOI: 10.1016/j.bbamcr.2007.11.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2007] [Revised: 11/01/2007] [Accepted: 11/05/2007] [Indexed: 01/10/2023]
|
4
|
Sonkusare S, Fraer M, Marsh JD, Rusch NJ. Disrupting calcium channel expression to lower blood pressure: new targeting of a well-known channel. Mol Interv 2007; 6:304-10. [PMID: 17200457 PMCID: PMC4917382 DOI: 10.1124/mi.6.6.3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Swapnil Sonkusare
- Department of Pharmacology & Toxicology, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR 72205-7199, USA.
| | | | | | | |
Collapse
|
5
|
Tang ZZ, Hong X, Wang J, Soong TW. Signature combinatorial splicing profiles of rat cardiac- and smooth-muscle Cav1.2 channels with distinct biophysical properties. Cell Calcium 2007; 41:417-28. [PMID: 16979758 DOI: 10.1016/j.ceca.2006.08.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2006] [Revised: 07/24/2006] [Accepted: 08/02/2006] [Indexed: 11/17/2022]
Abstract
l-type (Ca(v)1.2) voltage-gated calcium channels play an essential role in muscle contraction in the cardiovascular system. Alternative splicing of the pore-forming Ca(v)1.2 subunit provides potent means to enrich the functional diversity of the channels. There are 11 alternatively spliced exons identified in rat Ca(v)1.2 gene and random rearrangements may generate up to hundreds of combinatorial splicing profiles. Due to such complexity, the real combinatorial splicing profiles of Ca(v)1.2 have not been solved. This study investigated whether the 11 alternatively spliced exons are spliced randomly or linked and if linked, how many combinatorial splicing profiles can be arranged in cardiac- and smooth-muscle cells. By examining three full-length cDNA libraries of the Ca(v)1.2 transcripts isolated from rat heart and aorta, our results showed that the arrangements of some of the alternatively spliced exons are tissue-specific and tightly linked, giving rise to only 41 alternative combinatorial profiles, of which 29 have not been reported. Interestingly, the 41 combinatorial profiles were distinctively distributed in the three Ca(v)1.2 libraries and the one named "heart 1-50" contained unexpected splice variants. Significantly, the tissue-specific cardiac- and smooth-muscle combinatorial splicing profiles of Ca(v)1.2 channels demonstrated distinct electrophysiological properties that may help rationalize the differences observed in native currents. The unique sequences in these tissue-specific splice variants may provide the potential targets for drug design and screening.
Collapse
Affiliation(s)
- Zhen Zhi Tang
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Blk MD9, 2 Medical Drive, Singapore 117597, Singapore
| | | | | | | |
Collapse
|
6
|
Chang SY, Yong TF, Yu CY, Liang MC, Pletnikova O, Troncoso JC, Burgunder JM, Soong TW. Age and gender-dependent alternative splicing of P/Q-type calcium channel EF-hand. Neuroscience 2007; 145:1026-36. [PMID: 17291689 PMCID: PMC1978091 DOI: 10.1016/j.neuroscience.2006.12.054] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2006] [Revised: 12/23/2006] [Accepted: 12/28/2006] [Indexed: 11/25/2022]
Abstract
Ca(v)2.1 Ca(2+) channels (P/Q-type), which participate in various key roles in the CNS by mediating calcium influx, are extensively spliced. One of its alternatively-spliced exons is 37, which forms part of the EF hand. The expression of exon 37a (EFa form), but not exon 37b (EFb form), confers the channel an activity-dependent enhancement of channel opening known as Ca(2+)-dependent facilitation (CDF). In this study, we analyzed the trend of EF hand splice variant distributions in mouse, rat and human brain tissues. We observed a developmental switch in rodents, as well as an age and gender bias in human brain tissues, suggestive of a possible role of these EF hand splice variants in neurophysiological specialization. A parallel study performed on rodent brains showed that the data drawn from human and rodent tissues may not necessarily correlate in the process of aging.
Collapse
Affiliation(s)
- Siao Yun Chang
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, 2 Medical Drive, Singapore 117597
| | - Tan Fong Yong
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, 2 Medical Drive, Singapore 117597
| | - Chye Yun Yu
- National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore 308433
| | - Mui Cheng Liang
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, 2 Medical Drive, Singapore 117597
| | - Olga Pletnikova
- Departments of Pathology and Neurology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Juan C. Troncoso
- Departments of Pathology and Neurology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | | | - Tuck Wah Soong
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, 2 Medical Drive, Singapore 117597
- National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore 308433
- Department Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| |
Collapse
|
7
|
Chaudhuri D, Alseikhan BA, Chang SY, Soong TW, Yue DT. Developmental activation of calmodulin-dependent facilitation of cerebellar P-type Ca2+ current. J Neurosci 2006; 25:8282-94. [PMID: 16148236 PMCID: PMC6725527 DOI: 10.1523/jneurosci.2253-05.2005] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
P-type (CaV2.1) Ca2+ channels are a central conduit of neuronal Ca2+ entry, so their Ca2+ feedback regulation promises widespread neurobiological impact. Heterologous expression of recombinant CaV2.1 channels demonstrates that the Ca2+ sensor calmodulin can trigger Ca2+-dependent facilitation (CDF) of channel opening. This facilitation occurs when local Ca2+ influx through individual channels selectively activates the C-terminal lobe of calmodulin. In neurons, however, such calmodulin-mediated processes have yet to be detected, and CDF of native P-type current has thus far appeared different, arguably triggered by other Ca2+ sensing molecules. Here, in cerebellar Purkinje somata abundant with prototypic P-type channels, we find that the C-terminal lobe of calmodulin does produce CDF, and such facilitation augments Ca2+ entry during stimulation by repetitive action-potential and complex-spike waveforms. Beyond recapitulating key features of recombinant channels, these neurons exhibit an additional modulatory dimension: developmental upregulation of CDF during postnatal week 2. This phenomenon reflects increasing somatic expression of CaV2.1 splice variants that manifest CDF and progressive dendritic targeting of variants lacking CDF. Calmodulin-triggered facilitation is thus fundamental to native CaV2.1 and rapidly enhanced during early development.
Collapse
Affiliation(s)
- Dipayan Chaudhuri
- Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
| | | | | | | | | |
Collapse
|