Transcriptional analysis reveals a markedly reduced expression of the voltage-dependent calcium channel α2δ1 subunit in canine prostate cancer compared to benign prostatic hyperplasia.

[BACKGROUND] Despite its low incidence, the aggressive nature and high metastatic potential of canine prostate cancer (PC) make it a serious problem in veterinary medicine. However, knowledge of the molecular mechanisms and regulatory networks underlying the development and progression of canine PC is still limited. Using high-throughput methods, many PC-related genes have been identified by comparing gene expression profiles in malignant and non-malignant prostate tissues. In these studies, the reference group containing both normal and hyperplastic prostate tissues specimens was compared to the group composed of cancerous tissues specimens. However, this approach does not allow the exclusion of inflammation-related genes from those directly involved in PC development and progression. Furthermore, the RNA-Seq and microarray data were not validated by additional analyses, including immunohistochemistry (IHC). Therefore, to identify PC-specific genes, a comparative analysis of gene expression profiles in PC and benign prostate hyperplasia (BPH) tissue samples was performed using RNA-Seq, and the results were validated by Nano String technology, Western blotting (WB) and IHC.

[RESULTS] Using the NanoString assay, significant differences were identified for 12 genes, of which ASPM, CLU, TOP2A, TSPAN8/TM4SF3 and HELLS were overexpressed in PC compared to BPH, while ATP6V0A4, CACNA2D1, CLDN10, GOLGA4, KLK2, NKX3.1 and SERPINB6 were downregulated in PC. Validation of the differentially expressed genes (DEGs) at the protein level using WB and IHC revealed a highly decreased expression of the voltage-gated calcium channel subunit alpha-2 delta-1 (α2δ1), encoded by the CACNA2D1 gene, in PC samples compared to BPH.

[CONCLUSIONS] Our findings make α2δ1 protein a novel and promising diagnostic biomarker to differentiate PC from BPH.