To study the relationship between cadmium, zinc and mtDNA copy number in North Indian patients suffering from prostate cancer: A case control study

Abstract

Objective: To examine the variation of cadmium (Cd), zinc (Zn) and mitochondrial DNA (mtDNA) copy number in prostate cancer (PCa) patients and their age match controls and correlations with clinicopathological parameters.

Subjects and methods: This study was conducted between January 2012 and January 2015. Blood Cd and Zn level was measured by inductively coupled plasma spectrophotometer. The variation of mitochondrial copy number in blood was measured by real-time PCR. We scrutinized the correlation of Cd, Zn and mtDNA with clinicopathological parameters like prostate specific antigen (PSA) and [Gleason] score.

Results: Mean Cd level (μg/L ± SD) was significantly higher (3.89 ± 1.49) while Zn level was low (85 ± 10.4) in PCa patients comparison to control patients (2.92 ± 1.23; 116 ± 19.1). A wide  distribution of variance and higher mtDNA copy numbers were found in PCa patients [Range (fold difference) 1968–39,245 (17.4)] as compared to controls [10,178–332,243.9], (p value: 0.036). Clinicopathological analysis showed that Cd, Zn and mtDNA DNA copy numbers were significantly associated with increased [Gleason] score but not with serum PSA level (Zn: r = −0.68; Cd: r = 0.64; mtDNA: r = 0.84) (p < 0.05).

Conclusion: Cd, Zn and mtDNA copy number significantly correlate with [Gleason] score which suggests that the former may serve as marker for therapeutic guidance.

Keywords: Mitochondrial DNA copy number; Cadmium; Zinc; Prostate cancer; RT-PCR; Gleason score