Cancer de la prostate : les niveaux de preuve des biomarqueurs de la détection précoce

As part of an overall review on the role of PSA and other emerging biomarkers in the detection, diagnosis and treatment of prostate cancer, we present here a part of a review of the literature made by the working group Biologie de la Prostate (AFU, CNBH, SFBC, SFMN) on the use of PSA and other biomarkers in the early detection of prostate cancer with an assessment of the level of evidence.     

Changes in prostate cancer at radical prostatectomy during the prostate specific antigen era: an Italian experience

OBJECTIVE: To assess changes in prostate cancer clinical and pathologic features by review of 15 years' experience with radical prostatectomy. STUDY DESIGN: A total of 596 consecutive patients who underwent open or laparoscopic radical prostatectomy (RP) between 1991 and 2006 were included. All had clinically localized prostate cancer. Surgical specimens were analyzed or blindly reviewed by a uropathologist, and whole-mount sections were prepared. Statistical analysis evaluated whether significant changes in clinical and pathologic variables occurred over time. RESULTS: Median prostate specific antigen (PSA) values at diagnosis significantly decreased over time. Definite stage migration was observed, with significant increase of organ-confined tumors. Incidence of seminal vesicle and lymph node involvement declined steadily. Median tumor volume decreased significantly over time (p<0.001). Incidence of nonsignificant cancers at RP increased significantly, reaching 25.6% in 2006. PSA value has progressively lost correlation with prostate cancer volume and today correlates only with prostate gland volume. CONCLUSION: Prostate cancer stage and volume at diagnosis have steadily decreased in the last 15 years, likely reflecting increasing use of PSA testing. In early prostate cancer, PSA level no longer correlates with tumor volume.     

Imaging in the diagnosis and management of prostate cancer

The current diagnosis and management of prostate cancer is largely based on the use of serum prostate-specific antigen (PSA) and pathologic risk factors such as Gleason score and clinical stage. The use of serum PSA in clinical practice has resulted in significant stage migration and, as such, imaging modalities historically utilized to stage prostate cancer are no longer able to reliably identify the small amounts of prostate cancer most often found at presentation. Molecular imaging techniques have focused on improving sensitivity and specificity for cancer detection through knowledge of specific attributes of disease biology. The evolution of imaging techniques has created a new role for imaging in the management of prostate cancer.     

Levels of plasma glycan-binding auto-IgG biomarkers improve the accuracy of prostate cancer diagnosis

Strategies to improve the early diagnosis of prostate cancer will provide opportunities for earlier intervention. The blood-based prostate-specific antigen (PSA) assay is widely used for prostate cancer diagnosis but specificity of the assay is not satisfactory. An algorithm based on serum levels of PSA combined with other serum biomarkers may significantly improve prostate cancer diagnosis. Plasma glycan-binding IgG/IgM studies suggested that glycan patterns differ between normal and tumor cells. We hypothesize that in prostate cancer glycoproteins or glycolipids are secreted from tumor tissues into the blood and induce auto-immunoglobulin (Ig) production. A 24-glycan microarray and a 5-glycan subarray were developed using plasma samples obtained from 35 prostate cancer patients and 54 healthy subjects to identify glycan-binding auto-IgGs. Neu5Acα2-8Neu5Acα2-8Neu5Acα (G81)-binding auto-IgG was higher in prostate cancer samples and, when levels of G81-binding auto-IgG and growth differentiation factor-15 (GDF-15 or NAG-1) were combined with levels of PSA, the prediction rate of prostate cancer increased from 78.2% to 86.2% than with PSA levels alone. The G81 glycan-binding auto-IgG fraction was isolated from plasma samples using G81 glycan-affinity chromatography and identified by N-terminal sequencing of the 50 kDa heavy chain variable region of the IgG. G81 glycan-binding 25 kDa fibroblast growth factor-1 (FGF1) fragment was also identified by N-terminal sequencing. Our results demonstrated that a multiplex diagnostic combining G81 glycan-binding auto-IgG, GDF-15/NAG-1 and PSA (≥?2.1 ng PSA/ml for cancer) increased the specificity of prostate cancer diagnosis by 8%. The multiplex assessment could improve the early diagnosis of prostate cancer thereby allowing the prompt delivery of prostate cancer treatment.

     

Sp1 and Sp3 transcription factors upregulate the proximal promoter of the human prostate-specific antigen gene in prostate cancer cells

The serum level of prostate-specific antigen (PSA) is useful as a clinical marker for diagnosis and assessment of the progression of prostate cancer, and in evaluating the effectiveness of treatment. We characterized four Sp1/Sp3 binding sites in the proximal promoter of the PSA gene. In a luciferase assay, these sites contributed to the basal promoter activity in prostate cancer cells. In an electrophoretic mobility shift assay and chromatin immunoprecipitation assay, we confirmed that Sp1 and Sp3 bind to these sites. Overexpression of wild-type Sp1 and Sp3 further upregulated the promoter activity, whereas overexpression of the Sp1 dominant-negative form or addition of mithramycin A significantly reduced the promoter activity and the endogenous mRNA level of PSA. Among the four binding sites, a GC box located at nucleotides -53 to -48 was especially critical for basal promoter activity. These results indicate that Sp1 and Sp3 are involved in the basal expression of PSA in prostate cancer cells.     

Carbohydrate structure and differential binding of prostate specific antigen to Maackia amurensis lectin between prostate cancer and benign prostate hypertrophy

Serum prostate-specific antigen (PSA) assay is widely used for detection of prostate cancer. Because PSA is also synthesized from normal prostate, false positive diagnosis cannot be avoided by the conventional serum PSA test. To apply the cancer-associated carbohydrate alteration to the improvement of PSA assay, we first elucidated the structures of PSA purified from human seminal fluid. The predominant core structure of N-glycans of seminal fluid PSA was a complex type biantennary oligosaccharide and was consistent with the structure reported previously. However, we found the sialic acid alpha2-3 galactose linkage as an additional terminal carbohydrate structure on seminal fluid PSA. We then analyzed the carbohydrate moiety of serum PSA from the patients with prostate cancer and benign prostate hypertrophy using lectin affinity chromatography. Lectin binding was assessed by lectin affinity column chromatography followed by determining the amount of total and free PSA. Concanavalin A, Lens culinaris, Aleuria aurantia, Sambucus nigra, and Maackia amurensis lectins were tested for their binding to the carbohydrates on PSA. Among the lectins examined, the M. amurensis agglutinin-bound fraction of free serum PSA is increased in prostate cancer patients compared to benign prostate hypertrophy patients. The binding of PSA to M. amurensis agglutinin, which recognizes alpha2,3-linked sialic acid, was also confirmed by surface plasmon resonance analysis. These results suggest that the differential binding of free serum PSA to M. amurensis agglutinin lectin between prostate cancer and benign prostate hypertrophy could be a potential measure for diagnosis of prostate cancer.     

Lifestyle factors and prostate-specific antigen (PSA) testing in UK Biobank: Implications for epidemiological research

BackgroundThe central role of prostate-specific antigen (PSA) testing in the diagnosis of prostate cancer leads to the possibility that observational studies that report associations between risk factors and prostate cancer could be affected by detection bias. This study aims to investigate whether reported risk factors for prostate cancer are associated with PSA testing in a large middle-aged population-based cohort in the UK.MethodsThe cross-sectional association between a wide range of sociodemographic, lifestyle, dietary and health characteristics with PSA testing was examined in 212,039 men aged 40–69 years in UK Biobank.ResultsA total of 62,022 (29%) men reported they had ever had a PSA test. A wide range of factors was associated with a higher likelihood of PSA testing including age, height, education level, family history of prostate cancer, black ethnic origin, not being in paid/self-employment, living with a wife or partner, having had a vasectomy, being diagnosed with cancer or hypertension and having a high dietary intake of cereal, cooked and salad/raw vegetables, fresh fruit and tea. Conversely, socioeconomic deprivation, Asian ethnic origin, current smoking, low alcohol intake, high body-mass index, high coffee consumption and being diagnosed with diabetes, heart disease or stroke were associated with a lower likelihood of PSA testing.ConclusionsA variety of sociodemographic, lifestyle and health-related characteristics are associated with PSA testing, suggesting that observed associations of some of these traits with risk for prostate cancer in epidemiological studies may be, at least partially, due to detection bias.     

经直肠剪切波弹性成像技术联合血清CEA、PSA、FPSA对前列腺良恶性病变的鉴别诊断价值研究

摘要 目的：研究经直肠剪切波弹性成像技术（TRSWE）联合血清癌胚抗原（CEA）、前列腺特异性抗原（PSA）、游离前列腺特异性抗原（FPSA）对前列腺良恶性病变的鉴别诊断价值。方法：选取合肥市第二人民医院2019年1月～2022年6月收治的90例前列腺病变患者,根据病理检查分为前列腺癌组（47例）和前列腺良性病变组（43例）。对所有前列腺病变患者均行TRSWE检查,分析前列腺良恶性病变的图像差异以及弹性模量最大值（Emax）、弹性模量平均值（Emean）。检测所有前列腺病变患者的血清CEA、PSA、FPSA水平并进行对比。采用受试者工作特征（ROC）曲线分析明确Emax值、Emean值以及血清CEA、PSA、FPSA水平联合诊断前列腺良恶性病变的效能。结果：前列腺癌组Emax值、Emean值均高于前列腺良性病变组（均P＜0.05）。前列腺癌组血清CEA、PSA及FPSA水平均高于前列腺良性病变组（均P＜0.05）。经ROC曲线分析发现,Emax值、Emean值以及血清CEA、PSA、FPSA水平联合检测诊断前列腺良恶性病变的效能优于上述5项指标单独检测。结论：TRSWE联合血清CEA、PSA、FPSA对前列腺良恶性病变的鉴别诊断价值较高,可有效提升前列腺癌的检出率,可能值得临床推广应用。     

Glycotyping of prostate specific antigen

Measurement of serum levels of the prostate specific antigen (PSA) is now widely used for the diagnosis of prostate cancer and benign prostate hyperplasia. This serum marker is of value since it is derived only from the tissue of interest, but increased levels of PSA in serum do not allow a completely clear cut diagnosis of benign versus malignant changes. Since PSA is a glycoprotein with one asparagine linked oligosaccharide, and since malignant transformation often leads to an increased branching of such oligosaccharides, we initially studied the asparagine linked structures on PSA made by a cell line derived from malignant metastatic prostate tissue. We observed that unlike normal PSA, which bears only biantennary oligosaccharides, PSA from the metastatic cell line has a mixture of biantennary and triantennary oligosaccharides. Further experiments will reveal carbohydrate differences derived from the PSA from sera or, prostate tissue of normal versus prostate cancer patients, and of the utility of such carbo-hydrate differences as a possible diagnostic marker for prostate cancer.     

磁共振成像联合血清前列腺特异抗原、上皮钙黏蛋白、早期前列腺癌抗原-2诊断前列腺癌的临床价值探讨

摘要 目的：探究磁共振成像（MRI）联合血清前列腺特异抗原（PSA）、上皮钙黏蛋白（sE-cadherin）、早期前列腺癌抗原-2（EPCA-2）诊断前列腺癌的临床价值。方法：选取潍坊市人民医院2020年1月-2021年7月期间经病理证实的50例前列腺癌患者（前列腺组）以及50例前列腺增生患者（前列腺增生组）展开回顾性研究。100例研究对象均完善了MRI检查并测定血清PSA、EPCA-2、sE-cadherin水平,分析两组患者的MRI影像学特征,比较两组患者的PSA、EPCA-2、sE-cadherin水平以及各项检查方法的诊断准确性差异。结果：前列腺癌的MRI影像学特征为病灶主要位于外周带,外周带T2W呈低信号,病变侵及包膜、膀胱及周围组织具有T1加权消失或者不对称,具有信号异常、肌肉增厚的表现,盆腔淋巴结转移具有淋巴结部分融合或增大表现;前列腺增生的MRI影像学特征为边界清晰、包膜完整并且中央带增生、不均匀信号结节;前列腺癌、前列腺增生均存在不同程度的前列腺体积增大。相比于前列腺增生组,前列腺癌组患者的PSA、sE-cadherin、EPCA-2水平明显更高（P<0.05）。MRI、PSA、sE-cadherin、EPCA-2四项联合鉴别前列腺癌、前列腺增生的诊断符合率为96.00%,明显高于四项单独诊断的88.00%、79%、81%、82%（P<0.05）。结论：MRI联合PSA、sE-cadherin、EPCA-2鉴别诊断前列腺癌的准确性较高,具有作为临床前列腺癌早期诊断指导方案的潜力。     

前列腺特异性抗原在前列腺癌诊断中的应用进展

已经证明,前列腺特异性抗原（PSA）是一种有价值的前列腺癌（PCa)肿瘤标记物,血清PSA的广泛使用提高了前列腺癌的检出率,使晚期癌患得明显减少。然而,PSA对PCa的检测缺乏特异性,由于其高的假阳性率,引起许多不必要的活检。为了提高PSA对PCa诊断的特异性,降低不必要的活检,众多学正在探讨与PSA相关的几项参数的临床应用价值,本就此作一综述。     

A mechanistic insight into the anti-metastatic role of the prostate specific antigen

AimSince its discovery Prostate Specific Antigen (PSA), also referred to as kallikrein-3 (KLK3), has been used as standard circulating biomarker for prostate cancer (PCa). However, its specificity remains not adequate and its mechanism of action still elusive. Therefore, deciphering PSA role throughout PCa-pathobiology would be relevant in improving both cancer diagnosis and outcome prediction. We investigated the possible role played by PSA on/in the tumor microenvironment and over the first steps of cancer invasion.MethodsFresh PCa-specimens and cell lines were used for ex-vivo/in-vitro invasion assays and assessment of prostate tissue-PSA (tPSA), type 1 collagen (COL1A1) and ß1-integrin expression. Tissue Cancer Genome Atlas (TCGA) and Decipher® datasets were considered to estimate tPSA clinical relevance.ResultsA more precise, inverse, correspondence between tPSA and clinical/pathological parameters was found than for circulating PSA. KLK3 combined with Gleason grade and pathologic stage, better predicted cancer-related mortality. Consistently, we demonstrated that PSA inhibits prostate extracellular-matrix (ECM) invasion by PCa cells. As for the mechanism of action, we provided novel information that PSA is able to cleave COL1A1, a main component of the ECM. Finally, ß1-integrin, a crucial COL1A1 transducing-receptor involved in tumor adhesion/invasion, resulted to be downregulated in PCa specimens with higher levels of tPSA.ConclusionsBy interfering with type 1 collagen and its downstream targets, PSA may hamper adhesion and path of the cancer cells through ECM and their migration ability, thus explaining the inverse correlation highlighted between prostate tPSA levels and clinically significant disease.     

Mechanistic insights into the inhibition of prostate specific antigen by beta-lactam class compounds

Prostate Specific Antigen (PSA) is a biomarker used in the diagnosis of prostate cancer and to monitor therapeutic response. However, its precise role in prostate carcinogenesis and metastasis remains largely unknown. A number of studies arguing in the favor of an active role of PSA in prostate cancer development and progression have implicated this serine protease in the release and activation of growth factors such as insulin-like growth factor 1 (IGF1) through cleavage of insulin like growth factor binding protein 3 and Transforming Growth Factor beta (TGF-beta) through cleavage of Latent TGF-beta. In contrast, other studies suggest that PSA activity might hinder tumor development and progression. In light of these contradictory findings, efficient inhibitors of PSA are needed for exploring its biological role in tumor development and metastasis. Towards the goal of developing potent inhibitors of PSA, we have explored the molecular mechanism of a series of beta-lactam based compounds on binding to PSA using activity assays, matrix assisted laser desorption ionization with a time-of-flight mass spectrometry, and GOLD docking methodology. The mass spectrometry experiments and the activity assays confirmed the time-dependent and covalent nature of beta-lactam binding. To gain insights on the reaction intermediates at the molecular level, we docked beta-lactam inhibitors to a homology modeled PSA using the GOLD docking program in noncovalent and covalent binding modes. The docking studies elucidated the molecular details of the early noncovalent Michaelis complex, the acyl-enzyme covalent complex, and the nature of conformational reorganization required for the long term stability of the covalent complex. Additionally, the molecular basis for the effect of stereochemistry of the lactam ring on the inhibitory potency was elucidated through docking of beta-lactam enantiomers. As a validation of our docking methodology, two novel enantiomers were synthesized and evaluated for their inhibitory potency using fluorogenic substrate based activity assays. Additionally, cis enantiomers of eight beta-lactam compounds reported in a previous study were docked and their GOLD scores and binding modes were analyzed in order to assess the general applicability of our docking results. The close agreement of our docking results with the experimental data validates the mechanistic insights revealed through the docking studies and paves the way for the design and development of potent and specific inhibitors of PSA.     

Comparison of digital rectal examination and prostate specific antigen in early detection of prostate cancer

This study compares the value of digital rectal examination (DRE) and prostate specific antigen (PSA) determination in the detection of prostate cancer. 1,000 men aged > or = 50 from the Osijek surroundings were examined. The subjects with prostatitis were excluded from the study. The subjects with elevated concentration of total prostate specific antigen and/or digital rectal examination suspect of carcinoma underwent prostate biopsy. The rate of prostate cancer detection showed to be 3.3% for PSA > 4 ng/ml, 2% for abnormal finding of DRE, and 3.7% for combination of the two methods. Out of 35 patients with prostate cancer detected, 19 had suspect DRE finding and 32 had PSA exceeding 4 ng/ml. Thus, PSA pointed to the diagnosis of prostate cancer in 91.4%, and abnormal finding of DRE in 54.2% of cases, the difference being statistically significant. The positive predictive value was 48.7% for abnormal finding of DRE, 47% for PSA > 4 ng/ml, and 80.0% for the combination of both. Although PSA determination detected a considerable proportion of tumors missed on DRE, the former alone was found to be insufficient as a screening method because of its inadequate sensitivity. When combined with digital rectal examination, the probability of prostate cancer detection increased considerably.     

Optimisation de l’utilisation du PSA

PSA is a tumor marker usually determined for prostate cancer at diagnosis for its pronostic value and at therapy follow-up. But lack of specificity of PSA for prostate cancer and variability between assays demonstrated by the quality program survey make this marker not valuable in mass screening program. Market control of Afssaps on analysis devices of PSA showed a correct harmonization for total PSA. Biological tools available and easy to perform could improve ability of PSA for early detection of prostate cancer at a curable stage without induction of unnecessary biopsies prescribed because elevated total PSA values.     

Prostate Cancer Specificity of PCA3 Gene Testing: Examples from Clinical Practice

A specific marker for early prostate cancer would fill an important void. In initial evaluations of the prostate cancer antigen 3 (PCA3) gene vis-à-vis serum prostate-specific antigen (PSA) levels, the gene offers great promise. At the cellular level, PCA3 specificity for cancer is nearly perfect because of the gross overexpression of the gene by cancer cells. As a clinical test for early prostate cancer, heightened specificity is also seen in urine containing prostate cells from men with the disease. PCA3 gene testing holds valuable potential in PSA quandary situations: (1) men with elevated PSA levels but no cancer on initial biopsy; (2) men found to have cancer despite normal levels of PSA; (3) men with PSA elevations associated with varying degrees of prostatitis; and (4) men undergoing active surveillance for presumed microfocal disease.     

On the clinical usefulness of the free-to-total prostate-specific antigen ratio

The free-to-total prostate-specific antigen ratio (F/T PSA) is associated with the presence of prostate cancer and is thus used as an indicator for suspicion of prostate cancer and as a determinant for biopsy. We reviewed a recent retrospective series of 966 consecutive prostate biopsies where F/T PSA was blindly determined and did not influence biopsy indication. We simulated the association of F/T PSA with biopsy outcome and its impact as a biopsy determinant. When adopting an F/T PSA cutoff of 10%, 13%, 16% or 20% among random sextant biopsies in the 4-10 ng/mL total PSA range, the sensitivity was 15%, 37%, 55% and 72% and the specificity 89%, 80%, 64% and 44%, respectively. Using F/T PSA as a biopsy determinant, from 1.7 to 2.6 cancer biopsies would have been delayed to avoid 10 benign biopsies. As this balance is not acceptable, F/T PSA has no role as a biopsy indicator and its clinical use is questionable.