Characterization of CACNA2D3 as a putative tumor suppressor gene in the development and progression of nasopharyngeal carcinoma

Abstract

Apart from b-catenin accumulation, loss of 3p21 is one of the most frequent genetic alterations in numerous malignancies including nasopharyngeal carcinoma (NPC). Herein, we characterized a novel candidate tumor suppressor gene (TSG) CAC-NA2D3, a voltage-dependent subunit alpha 2 delta 3 of a calcium channel complex. Downregulation of CACNA2D3 was frequently detected in primary NPCs and NPC cell lines compared with their nontumorigenic counterparts. Attenuated CACNA2D3 expression may be associated with loss of heterozygosity (LOH) at intragenic single-nucleotide polymorphism sites (rs589281, rs1449325 and rs6797113) and/or epigenetic silencing by methylation and histone deacetylation. Given the extensive effects of calcium in cancer, we then investigated the tumor suppressive role and underlying mechanism of CACNA2D3 in the development and progression of NPC. CACNA2D3 was stably transfected into NPC cell lines (C666 and SUNE1) at levels comparative with the normal nasopharynx, alongside siRNA-mediated silencing in an immortalized nasopharyngeal epithelial cell line (NP69) to conduct in vivo and in vitro functional assays. Our findings show that CACNA2D3-mediated increase in intracellular calcium (Ca21) can induce mitochondrial-mediated apoptosis and activation of NLK (through the Wnt/Ca21 pathway) to antagonize Wnt signaling-mediated anchorage-dependent and independent cell proliferation (via CCND1 and CMYC), invasion (via MMP7) and epithelial-to-mesynchemal transition (via SNAIL). As the expression pattern of calcium channels and their degree of functionality can change with the progression of cancer, CACNA2D3 may indeed be a promising biomarker for NPC. Our study also warrants further exploration in the potential therapeutic use of existing epigenetic targeting drugs (e.g., 5-azacytidine, SAHA) to reconstitute CACNA2D3-associated tumor suppression in NPC.

Characterization of the Nasopharyngeal Carcinoma Methylome Identifies Aberrant Disruption of Key Signaling Pathways and Methylated Tumor Suppressor Genes

“…m m [43] ADAMTS9 m m [55] ADAMTS18 m m [56] CACNA2D3 m m [57] CADM1 m m [26,29] CCNA1 m m [58] CDH4 m m [59] CDH11 m m [41] CHFR m m [24,29] CMTM3 m m [45] CMTM7 m m [54] DACT1 m Verified in the current study -…”

CACNA2D3 is downregulated in gliomas and functions as a tumor suppressor

“…Downregulation of CACNA2D3 was shown by our findings to be a common feature of glioma tissue. Downregulation of CACNA2D3 has been correlated with extensive promoter hypermethylation in nasopharyngeal carcinoma cells [51] and in gastric carcinoma cells [23]. We also found that downregulation of CACNA2D3 in high-grade glioma cells and tissue was accompanied with increased methylation.…”

Diagnostic Capacity of RASSF1A Promoter Methylation as a Biomarker in Tissue, Brushing, and Blood Samples of Nasopharyngeal Carcinoma

“…Promoter methylation of tumor suppressor genes (TSGs), such as calcium channel voltage-dependent alpha 2/delta subunit 3 ( CACNA2D3 ) and cadherin 4 ( CDH4 ), may play a crucial role in NPC development and progression (Wong et al, 2013, Du et al, 2011). Localized in human chromosomal region 3p21.3, the RAS association domain family protein 1A ( RASSF1A ) is an important TSG involved in multiple biological functions, including cell cycle regulation, microtubule stabilization, and apoptosis (Allen et al, 2007, Agathanggelou et al, 2005, Burbee et al, 2001).…”