Application of a novel quantitative-PCR assay to investigate the role of Propionibacterium in the aetiology of prostate cancer

Recent studies suggest that P. acnes may be a frequent coloniser of prostate tissue, where it is associated with acute and chronic inflammatory changes which could potentially stimulate carcinogenesis. Culture methods for P. acnes detection are sub-optimal due to the slow growth of the organism coupled with the lack of sensitivity of end-point PCR, therefore, we have developed a novel quantitative TaqMan qPCR assay to detect and quantify Propionibacterium acnes in cancerous prostate tissue. Our developed assay employs the use of primers that target Propionibacterium specific regions of the 16S rRNA gene, in combination with the TaqMan probe which was designed to hybridise with P. acnes sequences only. PCR inhibition was eliminated using an established human endogenous retrovirus-3 assay which quantifies human cells present in clinical samples and simultaneously provides normalisation of the P. acnes genome count. DNA from a range of bacterial species was used to assess specificity of the assay. The assay was applied to DNA extracted from archived tissue specimens retrieved from prostate cancer patients in the UK. Archived prostate tissue from disease-free patients and non-prostatic tissue controls were compared. Our studies confirm the presence of P. acnes DNA in the prostate tissue of UK patients and reveal levels in cancerous prostates significantly higher than those found in control tissue (p