Circulating microRNAs as stable blood-based markers for cancer detection.

Improved approaches for the detection of common epithelial malignancies are urgently needed to reduce the worldwide morbidity and mortality caused by cancer. MicroRNAs (miRNAs) are small ( approximately 22 nt) regulatory RNAs that are frequently dysregulated in cancer and have shown promise as tissue-based markers for cancer classification and prognostication. We show here that miRNAs are present in human plasma in a remarkably stable form that is protected from endogenous RNase activity. miRNAs originating from human prostate cancer xenografts enter the circulation, are readily measured in plasma, and can robustly distinguish xenografted mice from controls. This concept extends to cancer in humans, where serum levels of miR-141 (a miRNA expressed in prostate cancer) can distinguish patients with prostate cancer from healthy controls. Our results establish the measurement of tumor-derived miRNAs in serum or plasma as an important approach for the blood-based detection of human cancer.

A multicenter evaluation of the PCA3 molecular urine test: pre-analytical effects, analytical performance, and diagnostic accuracy.

BACKGROUND: Measurement of prostate cancer gene 3 (PCA3) mRNA normalized to prostate-specific antigen (PSA) mRNA in urine has been proposed as a marker for prostate cancer. METHODS: We investigated pre-analytical effects, analytical performance, and diagnostic accuracy of a quantitative assay for PCA3. RESULTS: Urine specimens collected without prostate manipulation demonstrated low informative rates. However, specimens collected following digital rectal examinations of 3 or 8 strokes per prostate lobe demonstrated informative rates >94%. Across all urine specimen types, median PCA3 results did not show statistically significant differences (P>0.8). Measurements of controls of known mRNA content demonstrated percent recoveries of 100+/-15% for both PCA3 and PSA mRNAs. PCA3 mRNA total, intra-assay, inter-assay, and inter-site CVs were < or =17.1%, < or =14.0%, < or =9.9%, and < or =3.2%, respectively. Corresponding CVs for PSA mRNA assay were < or =11.5%, < or =8.6%, < or =7.9%, and < or =8.3%. Blinded assay of urines from 72 men with known prostate biopsy outcomes yielded areas under the curve from receiver-operating characteristic analysis of 0.7 at both research sites. Deming regression of individual PCA3 results between sites yielded slope=0.94, intercept=0.48, R=0.9677 (P<0.0001). CONCLUSIONS: The PCA3 assay is insensitive to pre-analytical factors, performs well analytically and correctly classifies a high percent of subjects with known prostate cancer status across research sites.

Elevation of cytokine levels in cachectic patients with prostate carcinoma.

BACKGROUND: Approximately 60-70% of patients with advanced prostate carcinoma (CaP) suffer from cachexia, one of the most devastating conditions associated with advanced malignant disease. The pathophysiology of cachexia is multifactorial, and several cytokines, such as tumor necrosis factor alpha (TNFalpha) and interleukin 1 (IL-1), IL-6, and IL-8, may be involved. The objective of the current study was to determine whether cachexia associated with advanced CaP is accompanied by increased serum levels of TNFalpha, IL-1beta, IL-6, and IL-8. METHODS: The levels of TNFalpha, IL-1beta, IL-6, IL-8, and prostate specific antigen (PSA) were examined in serum samples from normal donors (n = 10 donors), from patients with organ-confined CaP (n = 19 patients), from patients with advanced CaP without cachexia (n = 17 patients), and from patients with cachectic CaP (n = 26 patients). DPC Immulite and Abbott IMx Total-PSA assays were used to determine cytokine and PSA levels, respectively. RESULTS: Levels of TNFalpha, IL-6, and IL-8 were elevated significantly in the group of patients with advanced, cachectic CaP compared with patients who were without cachexia. In the cachectic patients, levels of TNFalpha were correlated positively with IL-8, and there was no correlation between PSA levels and any of the cytokine levels. IL-1beta levels were below the limit of detection in all samples. CONCLUSIONS: The current results show that levels of TNFalpha, IL-6, and IL-8 were increased in CaP patients with cachexia. Increased levels of these cytokines were not correlated with PSA levels, suggesting that they are regulated by a mechanism that is independent of PSA synthesis. Additional fundamental research is needed to determine the mechanisms involved and to identify potential therapeutic targets in patients with cachexia.