Detecting prostate cancer by intracellular macrophage prostate-specific antigen (PSA): a more specific and sensitive marker than conventional serum total PSA

Effect of radical prostatectomy on levels of cancer related epitopes in circulating macrophages of patients with clinically localized prostate cancer

OBJECTIVE

Epitopes of the apoptosis related protein DNaseX (Apo10) and the pentose-phosphate-pathway associated protein transketolase-like 1 (TKTL1) have been shown to be increased in circulating macrophages of patients with different cancer types including prostate cancer (PC). So far, the effect of cancer-specific therapies on the levels of these markers in blood samples of patients with PC has not been evaluated yet. The aim of the present study was to prospectively assess the effect of surgical removal of the prostate on levels of Apo10 and TKTL1 in blood macrophages using Epitope Detection In Monocytes (EDIM).

METHODS

We prospectively enrolled 174 patients with clinically localized PC undergoing radical prostatectomy. Peripheral blood was collected preoperatively in all patients and postoperatively in a subgroup of 72 patients. We separately assessed the proportion of CD14/CD16-positive monocytes expressing Apo10 and TKTL1 using flow cytometry. The proportion of positive cells was multiplied by ten to generate a score for Apo10 and TKTL1, separately. Pre- and postoperative scores of Apo10 and TKTL1 were compared. Moreover, results were correlated with clinicopathologic parameters.

RESULTS

In the total cohort, Median preoperative Apo10 and TKTL1 scores were 136 (Range 101-254) and 139 (102-216). In patients who underwent blood collection and testing either pre- and postoperatively (n = 72), median pre- versus postoperative scores were 132 (101-215) versus 103 (70-156) for Apo10 (P < 0.0001) and 140 (102-212) versus 115 (84-187) (P < 0.0001) for TKTL1. Following radical prostatectomy, 56 (77.7%) and 59 (81.9%) patients in the cohort of patients with blood collection before and after prostatectomy showed a decrease of Apo10 and TKTL1 expressing monocytes. TKTL1 and Apo10 did not show any correlation with known histopathologic and clinical risk parameters.

CONCLUSIONS

The present study demonstrates that surgical removal of the primary tumor leads to a significant decrease of Apo10 and TKTL1 expressing macrophages. This observation further encourages studies assessing the optimal clinical utility of EDIM-based detection of Apo10 and TKTL1 in patients with PC.

The use of a gas chromatography-sensor system combined with advanced statistical methods, towards the diagnosis of urological malignancies

Prostate cancer is one of the most common cancers. Serum prostate-specific antigen (PSA) is used to aid the selection of men undergoing biopsies. Its use remains controversial. We propose a GC-sensor algorithm system for classifying urine samples from patients with urological symptoms. This pilot study includes 155 men presenting to urology clinics, 58 were diagnosed with prostate cancer, 24 with bladder cancer and 73 with haematuria and or poor stream, without cancer. Principal component analysis (PCA) was applied to assess the discrimination achieved, while linear discriminant analysis (LDA) and support vector machine (SVM) were used as statistical models for sample classification. Leave-one-out cross-validation (LOOCV), repeated 10-fold cross-validation (10FoldCV), repeated double cross-validation (DoubleCV) and Monte Carlo permutations were applied to assess performance. Significant separation was found between prostate cancer and control samples, bladder cancer and controls and between bladder and prostate cancer samples. For prostate cancer diagnosis, the GC/SVM system classified samples with 95% sensitivity and 96% specificity after LOOCV. For bladder cancer diagnosis, the SVM reported 96% sensitivity and 100% specificity after LOOCV, while the DoubleCV reported 87% sensitivity and 99% specificity, with SVM showing 78% and 98% sensitivity between prostate and bladder cancer samples. Evaluation of the results of the Monte Carlo permutation of class labels obtained chance-like accuracy values around 50% suggesting the observed results for bladder cancer and prostate cancer detection are not due to over fitting. The results of the pilot study presented here indicate that the GC system is able to successfully identify patterns that allow classification of urine samples from patients with urological cancers. An accurate diagnosis based on urine samples would reduce the number of negative prostate biopsies performed, and the frequency of surveillance cystoscopy for bladder cancer patients. Larger cohort studies are planned to investigate the potential of this system. Future work may lead to non-invasive breath analyses for diagnosing urological conditions.

Urinary Volatile Organic Compounds for the Detection of Prostate Cancer

The aim of this work was to investigate volatile organic compounds (VOCs) emanating from urine samples to determine whether they can be used to classify samples into those from prostate cancer and non-cancer groups. Participants were men referred for a trans-rectal ultrasound-guided prostate biopsy because of an elevated prostate specific antigen (PSA) level or abnormal findings on digital rectal examination. Urine samples were collected from patients with prostate cancer (n = 59) and cancer-free controls (n = 43), on the day of their biopsy, prior to their procedure. VOCs from the headspace of basified urine samples were extracted using solid-phase micro-extraction and analysed by gas chromatography/mass spectrometry. Classifiers were developed using Random Forest (RF) and Linear Discriminant Analysis (LDA) classification techniques. PSA alone had an accuracy of 62–64% in these samples. A model based on 4 VOCs, 2,6-dimethyl-7-octen-2-ol, pentanal, 3-octanone, and 2-octanone, was marginally more accurate 63–65%. When combined, PSA level and these four VOCs had mean accuracies of 74% and 65%, using RF and LDA, respectively. With repeated double cross-validation, the mean accuracies fell to 71% and 65%, using RF and LDA, respectively. Results from VOC profiling of urine headspace are encouraging and suggest that there are other metabolomic avenues worth exploring which could help improve the stratification of men at risk of prostate cancer. This study also adds to our knowledge on the profile of compounds found in basified urine, from controls and cancer patients, which is useful information for future studies comparing the urine from patients with other disease states.

The dual role of paramagnetic particles for integrated lysis and measurement in a rapid immunoassay for intracellular proteins

A novel, integrated lysis and immunoassay methodology and system for intracellular protein measurement are described. The method uses paramagnetic particles both as a lysis agent and assay label resulting in a rapid test requiring minimal operator intervention, the test being homogeneous and completed in less than 10 min. A design study highlights the critical features of the magnetic detection system used to quantify the paramagnetic particles and a novel frequency-locked loop-based magnetometer is presented. A study of paramagnetic particle enhanced lysis demonstrates that the technique is more than twice as efficient at releasing intracellular protein as ultrasonic lysis alone. Results are presented for measurements of intracellular prostate specific antigen in an LNCAP cell line. This model was selected to demonstrate the rapidity and efficiency of intracellular protein quantification. It was shown that, on average, LNCAP cells contained 0.43 fg of prostate specific antigen. This system promises an attractive solution for applications that require a rapid determination of intracellular proteins.

Prostate-specific antigen testing across the spectrum of prostate cancer

Prostate-specific antigen (PSA) is a protein produced by the prostate, and this protein may be elevated for several reasons, including prostatitis, benign prostatic hypertrophy and/or cancer. PSA is not cancer-specific, cannot be used as a cancer marker and it has been demonstrated that there is no level of PSA that is definitive for prostate cancer. The value of the PSA test varies when used for screening, diagnosis, prognosis or as a signal of disease recurrence. Misuse of the test for screening has created unnecessary anxiety and costs, and has led to the significant overdiagnosis and overtreatment of men. More important than whether or not to screen is how one acts upon the data from a single test; with the exception of extremely high double- or triple-digit levels of PSA, it is prudent only to use a single PSA determination as a baseline, with biopsy and cancer treatment reserved for those with significant PSA changes over time, or for those with clinical manifestations mandating immediate therapy. Using the PSA test to monitor disease progression or recurrence is appropriate, provided one understands that absolute levels of PSA are rarely meaningful; it is the relative change in PSA levels over time that provides insight, but not definitive proof of a cancerous condition necessitating therapy. PSA secretion is under hormonal control and thus PSA levels may be affected differently by the type of drug therapy, by the stage of a patients' disease, and by genetic factors suggesting some men are 'high PSA producers'. Until a validated alternative test for prostate cancer is found and adopted, the current flawed PSA test needs to be used more judiciously and not used for routine screening as studies have demonstrated that screening, as defined, does not lead to a reduction in patient mortality. All men, their families and their physicians need to understand the significant limitations of PSA testing.