Current molecular diagnostics of
prostate cancer relies on detection of elevated levels of PSA
protein in serum, but its specificity has been questioned due to its higher levels also in non-malignant prostate diseases. A
long non-coding RNA biomarker, PCA3, demonstrated excellent specificity for
prostate cancer, and thus has become an interesting alternative to PSA monitoring. Its detection utilizes mostly reverse transcription PCR with optical detection, making the protocol longer and more expensive. To avoid PCR, we have developed an electrochemical assay coupled with LAMP, an isothermal amplification technique showing high sensitivities at constant temperatures and shorter reaction times. We amplified PCA3
RNA as well as PSA
mRNA (serving as a control), hybridized LAMP products on magnetic beads and measured them with chronoamperometry at
carbon electrode chips. We show good sensitivity and specificity for both
biomarkers in
prostate cancer cell lines, and successful detection of PCA3 in clinical samples, i.e., urine samples from 11
prostate cancer patients and 7 healthy controls, where we obtained excellent correlation with clinical data. This is to our knowledge a first such attempt to apply electrochemistry to determine two
RNA biomarkers directly in urine samples of
prostate cancer patients in a minimally invasive diagnostics format.