Prognostic value of serum markers for prostate cancer

Precision molecular insights for prostate cancer prognosis: tumor immune microenvironment and cell death analysis of senescence-related genes by machine learning and single-cell analysis

BACKGROUND

Prostate cancer (PCa) is a prevalent malignancy among men, primarily originating from the prostate epithelium. It ranks first in global cancer incidence and second in mortality rates, with a rising trend in China. PCa's subtle initial symptoms, such as urinary issues, necessitate diagnostic measures like digital rectal examination, prostate-specific antigen (PSA) testing, and tissue biopsy. Advanced PCa management typically involves a multifaceted approach encompassing surgery, radiation, chemotherapy, and hormonal therapy. The involvement of aging genes in PCa development and progression, particularly through the mTOR pathway, has garnered increasing attention.

METHODS

This study aimed to explore the association between aging genes and biochemical PCa recurrence and construct predictive models. Utilizing public gene expression datasets (GSE70768, GSE116918, and TCGA), we conducted extensive analyses, including Cox regression, functional enrichment, immune cell infiltration estimation, and drug sensitivity assessments. The constructed risk score model, based on aging-related genes (ARGs), demonstrated superior predictive capability for PCa prognosis compared to conventional clinical features. High-risk genes positively correlated with risk, while low-risk genes displayed a negative correlation.

RESULTS

An ARGs-based risk score model was developed and validated for predicting prognosis in prostate adenocarcinoma (PRAD) patients. LASSO regression analysis and cross-validation plots were employed to select ARGs with prognostic significance. The risk score outperformed traditional clinicopathological features in predicting PRAD prognosis, as evidenced by its high AUC (0.787). The model demonstrated good sensitivity and specificity, with AUC values of 0.67, 0.675, 0.696, and 0.696 at 1, 3, 5, and 8 years, respectively, in the GEO cohort. Similar AUC values were observed in the TCGA cohort at 1, 3, and 5 years (0.67, 0.659, 0.667, and 0.743). The model included 12 genes, with high-risk genes positively correlated with risk and low-risk genes negatively correlated.

CONCLUSIONS

This study presents a robust ARGs-based risk score model for predicting biochemical recurrence in PCa patients, highlighting the potential significance of aging genes in PCa prognosis and offering enhanced predictive accuracy compared to traditional clinical parameters. These findings open new avenues for research on PCa recurrence prediction and therapeutic strategies.

Are higher pre-diagnosis follicle stimulating hormone levels associated with long-term prostate cancer risk?

BACKGROUND

Follicle stimulating hormone (FSH) is a pituitary hormone that helps regulate testosterone homeostasis. Although it is generally accepted that FSH levels increase with LHRH-agonist therapy for prostate cancer (PC), the specific impact of FSH levels on risk of PC diagnosis is largely unknown. The objective of this study was to perform a population-level analysis to assess the association between FSH levels and PC diagnosis.

METHODS

All men (n = 386,018) who had a pre-PC diagnosis FSH level and complete data were identified within the Veterans Affairs Health System between 1999 and 2018. The association between FSH level and time from FSH test to PC diagnosis was tested using stratified Cox proportional hazards models. Multivariable models were adjusted for age, year, race, body mass index, and Charlson comorbidity index. Due to nonproportional hazards over time, time to PC was modeled separately: ≤4 years after an FSH test and >4 years following an FSH test.

RESULTS

Median age at first FSH level was 64 years (interquartile range [IQR]: 54-72), median year of FSH was 2010 (IQR: 2005-2014), and 70% of the cohort was white. Median follow-up was 76 months (IQR: 38-126) during which 17,519 men (4.5%) were diagnosed with PC. On multivariable analysis, in the first 4 years after FSH test, there was no association between FSH and time to PC diagnosis. Starting from 4 years after FSH test, on multivariable analysis, a higher FSH level was associated with lower risk of PC with continuous modeling, but found no association with log continuous and categorical modeling.

CONCLUSIONS

In this population-level study among male veterans receiving an FSH test for an unknown clinical indication, associations between FSH levels and PC risk were inconsistent and likely driven by selection bias and confounding variables. Future studies should consider different study designs.

Predictive value of collagen in cancer

Cancer is a complex disease and a significant cause of mortality worldwide. Over the course of nearly all cancer types, collagen within the tumor microenvironment influences emergence, progression, and metastasis. This review discusses collagen regulation within the tumor microenvironment, pathological involvement of collagen, and predictive values of collagen and related extracellular matrix components in main cancer types. A survey of predictive tests leveraging collagen assays using clinical cohorts is presented. A conclusion is that collagen has high predictive value in monitoring cancer processes and stratifying by outcomes. New approaches should be considered that continue to define molecular facets of collagen related to cancer.

Targeting macrophage-mediated tumor cell phagocytosis: An overview of phagocytosis checkpoints blockade, nanomedicine intervention, and engineered CAR-macrophage therapy

Immunotherapy has been developing at an unprecedented speed with promising therapeutic outcomes in the wide spectrum of cancers. Up until now, most immunotherapies have focused on adaptive immunity; however, investigating the potential of macrophage phagocytosis and consequent adaptive immune cross-priming has led to a growing interest in exploiting macrophages in cancer therapy. In light of the positive evidence from preclinical studies and early clinical data, targeting macrophage phagocytosis has become a promising therapeutic strategy. Here, we review therapies based on harnessing and amplifying macrophage phagocytosis, such as blocking phagocytosis checkpoints and exploiting nanoparticles as efficient approaches in elevating macrophages-mediated phagocytosis. The present study introduces CAR-macrophage as the state-of-the-art modality serving as the bridge between the innate and adaptive immune system to mount a superior anti-tumor response in the treatment of cancer. We also take a look at the recent reports of therapies based on CAR-engineered macrophages with the hope of providing a future research direction for expanding the application of CAR-macrophage therapy.

Multiplexed Prostate Cancer Companion Diagnostic Devices

Prostate cancer (PCa) remains one of the most prominent forms of cancer for men. Since the early 1990s, Prostate-Specific Antigen (PSA) has been a commonly recognized PCa-associated protein biomarker. However, PSA testing has been shown to lack in specificity and sensitivity when needed to diagnose, monitor and/or treat PCa patients successfully. One enhancement could include the simultaneous detection of multiple PCa-associated protein biomarkers alongside PSA, also known as multiplexing. If conventional methods such as the enzyme-linked immunosorbent assay (ELISA) are used, multiplexed detection of such protein biomarkers can result in an increase in the required sample volume, in the complexity of the analytical procedures, and in adding to the cost. Using companion diagnostic devices such as biosensors, which can be portable and cost-effective with multiplexing capacities, may address these limitations. This review explores recent research for multiplexed PCa protein biomarker detection using optical and electrochemical biosensor platforms. Some of the novel and potential serum-based PCa protein biomarkers will be discussed in this review. In addition, this review discusses the importance of converting research protocols into multiplex point-of-care testing (xPOCT) devices to be used in near-patient settings, providing a more personalized approach to PCa patients’ diagnostic, surveillance and treatment management.

OXPHOS remodeling in high-grade prostate cancer involves mtDNA mutations and increased succinate oxidation

Rewiring of energy metabolism and adaptation of mitochondria are considered to impact on prostate cancer development and progression. Here, we report on mitochondrial respiration, DNA mutations and gene expression in paired benign/malignant human prostate tissue samples. Results reveal reduced respiratory capacities with NADH-pathway substrates glutamate and malate in malignant tissue and a significant metabolic shift towards higher succinate oxidation, particularly in high-grade tumors. The load of potentially deleterious mitochondrial-DNA mutations is higher in tumors and associated with unfavorable risk factors. High levels of potentially deleterious mutations in mitochondrial Complex I-encoding genes are associated with a 70% reduction in NADH-pathway capacity and compensation by increased succinate-pathway capacity. Structural analyses of these mutations reveal amino acid alterations leading to potentially deleterious effects on Complex I, supporting a causal relationship. A metagene signature extracted from the transcriptome of tumor samples exhibiting a severe mitochondrial phenotype enables identification of tumors with shorter survival times.

Enhanced anti-tumor activity of the Multi-Leu peptide PACE4 inhibitor transformed into an albumin-bound tumor-targeting prodrug

The proprotein convertase PACE4 has been validated as a potential target to develop new therapeutic interventions in prostate cancer (PCa). So far, the most effective compound blocking the activity of this enzyme has been designed based on the structure of a small peptide Ac-LLLLRVKR-NH₂ known as the Multi-Leu (ML) peptide. Optimization of this scaffold led to the synthesis of compound C23 (Ac-[DLeu]LLLRVK-amidinobenzylamide) with a potent in vivo inhibitory effect on the tumor growth. However, further developments of PACE4 inhibitors may require additional improvements to counter their rapid renal clearance and to increase their tumor targeting efficiency. Herein, we explored the transformation of the ML-peptide into an albumin-binding prodrug containing a tumor specific release mechanism based on the prostate-specific antigen. Our data confirms that intravenous treatment using the ML-peptide alone has little effect on tumor growth, whereas by using the ML-prodrug in LNCaP xenograft-bearing mice it was significantly reduced. Additionally, excellent in vivo stability and tumor-targeting efficiency was demonstrated using a radiolabelled version of this compound. Taken together, these results provide a solid foundation for further development of targeted PACE4 inhibition in PCa.

Simultaneous Measurements of Follicle Stimulating Hormone and Total Testosterone and Associations in Clinically Localized Prostate Cancer

OBJECTIVES

To evaluate the potential relations of simultaneous measurements of basal levels of follicle stimulating hormone (FSH) and total testosterone (TT) in clinically localized prostate cancer (PCa).

MATERIALS AND METHODS

The study included 126 patients who had simultaneous measurements of prostate specific antigen (PSA), FSH, and TT before undergoing radical prostatectomy for clinically localized PCa. Correlations and independent associations between clinical and pathological factors were investigated by statistical methods.

RESULTS

The tumor volume (TV) was directly correlated to PSA and TT which was inversely related to FSH. Moreover, it was independently associated with both PSA and TT. In a multivariate linear regression model, FSH and TV were simultaneous independent factors associated with TT, and the association was inverse in the former and direct in the latter. In the patient population, the subset with FSH levels above the third quartile was related to lower median levels of TT that were associated with high grade cancer showing a lower TV. In localized PCa, basal levels of TT were associated with tumor parameters and inversely related to FSH levels, and the subset FSH levels above the third quartile were related to lower TT levels that were associated with high grade cancers showing a lower tumor load.

CONCLUSION

Preoperative TT was associated with tumor parameters and inversely related to FSH levels. Patient with increased FSH levels was related to lower levels of TT, which was associated with high grade cancer.

Early and multiple PSA bounces can occur following high-dose prostate stereotactic body radiation therapy: Subset analysis of a phase 1/2 trial

PURPOSE

We hypothesized that high-dose stereotactic body radiation therapy (SBRT) would lead to faster time to nadir and lower nadir values compared with conventional radiation therapy experiences. We now report prostate-specific antigen (PSA) kinetics following high-dose SBRT in patients treated with radiation alone.

METHODS AND MATERIALS

Ninety-one patients were enrolled on the phase 1/2 dose escalation study of SBRT for localized prostate cancer. All patients with at least 36 months of follow-up and without hormone therapy were included in this analysis (n = 47). Treatment response parameters evaluated include time to nadir, nadir value, occurrence of PSA bounces (rise of ≥0.2 ng/mL followed by a subsequent fall), magnitude of bounces, duration of bounces, and correlation of bounces with clinical outcomes.

RESULTS

Median follow-up was 42 months (range, 36-78 months). Treatment dose levels were 45 Gy (n = 10), 47.5 Gy (n = 8), and 50 Gy (n = 29) in 5 fractions. Biochemical control rate was 98%. Median PSA at follow-up was 0.10 ± 0.20 ng/mL. Median time to nadir was 36 ± 11 months. A total of 24/47 (51.1%) patients had ≥1 PSA bounce. Median magnitude of PSA rise during bounce was 0.50 ± 1.2 ng/mL. Median time to first bounce was 9 ± 7.0 months. Median bounce duration was 3 ± 2.3 months for the first bounce and 6 ± 5.2 months for subsequent bounces. Prostate volumes <30 mL were associated with a decreased likelihood of bounce (P = .0202), and increasing prostate volume correlated with increasingly likelihood of having ≥2 bounces (P = .027). Patients reaching PSA nadir of ≤0.1 ng/mL were less likely to experience any bounce (P = .0044).

CONCLUSIONS

Compared with other SBRT experiences, our study demonstrated a higher PSA bounce rate, a similar or shorter median time to bounce, and a very low nadir. Prostate volume appears correlated with bounce.

Active surveillance for prostate cancer: a narrative review of clinical guidelines

In the past decade active surveillance (AS) of men with localized prostate cancer has become an increasingly popular management option, and a range of clinical guidelines have been published on this topic. Existing guidelines regarding AS for prostate cancer vary widely, but predominantly state that the most suitable patients for AS are those with pretreatment clinical stage T1c or T2 tumours, serum PSA levels <10 ng/ml, biopsy Gleason scores of 6 or less, a maximum of one or two tumour-positive biopsy core samples and/or a maximum of 50% of cancer per core sample. Following initiation of an AS programme, most guidelines recommend serial serum PSA measurements, digital rectal examinations and surveillance biopsies to check for and identify pathological indications of tumour progression. Definitions of disease reclassification and progression differ among guidelines and multiple criteria for initiation of definitive treatment are proposed. The variety of descriptions of criteria for clinically insignificant prostate cancer indicates a lack of consensus on optimal AS and intervention thresholds. A single set of guidelines are needed in order to reduce variations in clinical practice and to optimize clinical decision-making. To enable truly evidence-based guidelines, further research that combines existing evidence, while also gathering information from more long-term studies is needed.

Incidental detection of prostate-specific antigen-negative metastatic prostate cancer initially presented with solitary pulmonary nodule on fluorodeoxyglucose positron emission tomography/computed tomography

A 71-year-old male patient with solitary pulmonary nodule underwent fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) showing slightly increased FDG uptake in this nodule. In addition, PET/CT detected hypermetabolic sclerotic bone lesions in the right second rib and 7^th thoracic vertebrae, which were interpreted as possible metastases, and mildly increased FDG uptake in the prostate gland highly suspicious of malignancy. The patient's prostate-specific antigen (PSA) level was within normal range (3.8 ng/dL). The histopathological examination of the lung nodule and right second rib lesion proved metastases from prostate cancer, then the prostate biopsy-confirmed prostate adenocarcinoma. The unique feature of this case is to emphasize the importance of performing PET/CT for solitary pulmonary nodule in detecting PSA-negative metastatic prostate cancer. This case indicated that it should be kept in mind that, even if the PSA is negative, a lung metastasis of prostate cancer may be an underlying cause in patients evaluated for solitary pulmonary nodule by FDG PET/CT.

Validation of algorithms to detect distant metastases in men with prostate cancer using routine registry data in Denmark

Objective

Among patients with prostate cancer, diagnostic codes for bone metastases in the Danish National Registry of Patients have a sensitivity of 44%. In an attempt to improve the sensitivity of registry-based identification of metastases from prostate cancer, we tested a series of algorithms, combining elevated prostate-specific antigen (PSA) levels, use of antiresorptive therapy, and performed bone scintigraphy.

Patients and methods

We randomly selected 212 men diagnosed with prostate cancer in 2005–2010 in the Central Denmark Region with prespecified PSA values, antiresorptive therapy, and bone scintigraphy who did not have a registry-based diagnostic code indicating presence of distant metastases. We defined three candidate algorithms for bone metastases: 1) PSA >50 μg/L and bone scintigraphy, 2) PSA >50 μg/L and antiresorptive therapy, and 3) PSA ≤50 μg/L with antiresorptive therapy or bone scintigraphy. An algorithm for distant metastasis site other than bone was defined as PSA >50 μg/L alone. Medical chart review was used as the reference standard to establish the presence or absence of metastases. Validity was expressed as a positive predictive value (PPV) or a negative predictive value, based on whether the algorithms correctly classified metastases compared with the reference standard.

Results

We identified 113 men with evidence of metastases according to the candidate algorithms, and 99 men without evidence of metastases according to the candidate algorithm. The PPVs of PSA >50 μg/L were 0.10 (95% confidence interval [CI] 0.04–0.19) for bone metastases and 0.14 (95% CI 0.07–0.24) for nonbone metastases, regardless of receipt of antiresorptive therapy or presence of bone scintigraphy. The PPVs for any metastases were 0.16 (95% CI 0.06–0.32) for PSA >50 μg/L and 0.28 (95% CI 0.14–0.47) for PSA >50 μg/L with bone scintigraphy. Adding antiresorptive treatment to the algorithm did not improve PPV. All negative predictive values approached 1.00.

Conclusion

Algorithms based on elevated PSA, antiresorptive therapy, or bone scintigraphy are not suitable for supplementing diagnostic codes to identify additional cases of distant metastases among men with prostate cancer. However, it is possible that in this setting, medical chart review is not a gold standard to identify metastases.

Proteolytic activity of prostate-specific antigen (PSA) towards protein substrates and effect of peptides stimulating PSA activity

Prostate-specific antigen (PSA or kallikrein-related peptidase-3, KLK3) exerts chymotrypsin-like proteolytic activity. The main biological function of PSA is the liquefaction of the clot formed after ejaculation by cleavage of semenogelins I and II in seminal fluid. PSA also cleaves several other substrates, which may explain its putative functions in prostate cancer and its antiangiogenic activity. We compared the proteolytic efficiency of PSA towards several protein and peptide substrates and studied the effect of peptides stimulating the activity of PSA with these substrates. An endothelial cell tube formation model was used to analyze the effect of PSA-degraded protein fragments on angiogenesis. We showed that PSA degrades semenogelins I and II much more efficiently than other previously identified protein substrates, e.g., fibronectin, galectin-3 and IGFBP-3. We identified nidogen-1 as a new substrate for PSA. Peptides B2 and C4 that stimulate the activity of PSA towards small peptide substrates also enhanced the proteolytic activity of PSA towards protein substrates. Nidogen-1, galectin-3 or their fragments produced by PSA did not have any effect on endothelial cell tube formation. Although PSA cleaves several other protein substrates, in addition to semenogelins, the physiological importance of this activity remains speculative. The PSA levels in prostate are very high, but several other highly active proteases, such as hK2 and trypsin, are also expressed in the prostate and may cleave protein substrates that are weakly cleaved by PSA.

Replacement of the Disulfide Bridge in a KLK3-Stimulating Peptide Using Orthogonally Protected Building Blocks

Peptide "B-2", which is one of the most potent kallikrein-related peptidase 3 (KLK3)-stimulating compounds, consists of 12 amino acids and is cyclized by a disulfide bridge between the N- and C-terminal cysteines. Orthogonally protected building blocks were used in the peptide synthesis to introduce a disulfide bridge mimetic consisting of four carbon atoms. The resulting pseudopeptides with alkane and E-alkene linkers doubled the proteolytic activity of KLK3 at a concentration of 14 μM. They were almost as potent as the parent "B-2" peptide, which gives a 3.6-fold increase in the proteolytic activity of KLK3 at the same concentration.

PSA forms complexes with α1-antichymotrypsin in prostate

BACKGROUND

PSA is the most useful prostate cancer marker. However, its levels are increased also in some non-malignant conditions. In circulation, the majority of PSA is complexed with protease inhibitors, including α(1) -antichymotrypsin (ACT). The proportion of the PSA-ACT complex is higher in patients with prostate cancer than in controls without cancer. The expression of ACT has been shown to be higher in prostate cancer than in benign prostatic hyperplasia. However, results regarding the extent which PSA forms complexes within the prostate and whether there are differences in complex formation between normal and malignant prostatic tissue are inconsistent and limited.

METHODS

We studied complex formation of PSA secreted by cultured human prostate tissues and in the tissue by in situ proximity ligation assay (PLA). Free, total and active PSA, and the PSA-ACT complex were determined in tissue culture media by immunoassays, immunoblotting, and chromatographic methods.

RESULTS

The majority of PSA in tissue culture medium was free and enzymatically active. However, a significant proportion (1.6 ± 0.5%) of immunoreactive PSA was found to be complexed with ACT. Complex formation was confirmed by in situ PLA, which showed more intense staining of PSA-ACT in cancers with Gleason grade 3 than in adjacent benign tissues from the same patients.

CONCLUSIONS

These results show that PSA forms complexes already within the prostate and that PSA-ACT levels are increased in moderately differentiated prostate cancer tissue. This may explain, at least partially, why the ratio of serum PSA-ACT to total PSA is increased in prostate cancer.

Investigative clinical study on prostate cancer part VI: Follicle-stimulating hormone and the pituitary-testicular-prostate axis at the time of initial diagnosis and subsequent cluster selection of the patient population

AIM

To evaluate the physiopathology of follicle-stimulating hormone (FSH) along the pituitary-testicular-prostate axis at the time of initial diagnosis of prostate cancer in relation to the available clinical variables and to the subsequent cluster selection of the patient population.

PATIENTS AND METHODS

The study included 98 patients who were diagnosed with prostate cancer. Age, percentages of positive cores (P+) at transrectal ultrasound scan biopsy, biopsy Gleason score (bGS), luteinizing hormone (LH), FSH, total testosterone, free testosterone (FT) and prostate-specific antigen (PSA) were the continuous clinical variables. All patients had not previously received hormonal manipulations. FSH correlation and multiple linear analyses were computed in the population. The FSH/PSA ratio was computed and then ranked for clustering the population as groups A (0.13≤FSH/PSA≤0.57), B (0.57<FSH/PSA≤1.61) and C (1.61<FSH/PSA≤19.4). The model was assessed by simple linear and multiple linear regression analysis and differences between the groups were assessed by analysis of variance.

RESULTS

In the patient population, FSH correlated to LH (p < 0.0001), FT (p = 0.007) and age (p = 0.004). FSH was independently predicted by both LH (p < 0.0001) and PSA (p = 0.04). PSA predicted FSH/PSA A (p < 0.0001), B (p < 0.0001) and C (p = 0.04). On multiple regression analysis, FSH/PSA A was predicted by PSA (p < 0.0001), P+ (p = 0.03) and bGS (p = 0.04); FSH/PSA B by LH (p = 0.002) and PSA (p < 0.0001); FSH/PSA C by LH (p < 0.0001) and PSA (p < 0.0001). Moreover, FSH/PSA A, B and C differed for mean values of FSH (p < 0.0001), LH (p < 0.0001), PSA (p < 0.0001) and PSA/FT ratio (p < 0.0001). FSH/PSA clusters showed features of decreasing aggressive disease as the FSH/PSA ratio progressed from A to C.

CONCLUSION

At the diagnosis of prostate cancer and along the pituitary-testis-prostate axis in a patient population FSH significantly correlated to LH, FT and age, and FSH was independently and significantly predicted by both LH and PSA. Because of the independent prediction of PSA by FSH, the prostate cancer population at diagnosis was clustered and ranked according to the FSH/PSA ratio in groups A, B and C. Also, the predictive model of PSA on FSH for the different groups proved to be effective at selecting potential prognostic clusters in which the risk of progression might be assessed as low (group C), intermediate (group B) and high (group A). The FSH/PSA model might be considered as a tool for prostate cancer study and for use in individualized, risk-adapted approaches. However, confirmatory studies are needed.

Increases in quantitative D-dimer levels correlate with progressive disease better than circulating tumor cell counts in patients with refractory prostate cancer

Changes in quantitative D-dimer levels, circulating tumor cell (CTC) counts, and prostate-specific antigen (PSA) levels were measured in 28 patients with refractory castration-resistant prostate cancer to assess their concordance during the course of therapy and their relationship with risk of progressive disease. A significant correlation was identified between changes in PSA and both CTC counts and D-dimer levels (r = 0.67 and 0.58, respectively; P < .001). In addition, there was a significant correlation between changes in CTC count and D-dimer level (r = 0.62; P < .001). A significantly stronger concordance between these biomarkers was noted for increasing values (sensitivity, 72%-77.8%) compared with decreasing values (specificity, 43.8%-71.4%). Notably, increases in PSA and D-dimer levels, not CTC counts, were associated with increased risks for progressive disease (P < .024). Increases in quantitative D-dimer levels correlate with progressive disease better than CTC counts in patients with refractory prostate cancer.

Investigative clinical study on prostate cancer: on the role of the pretreatment total PSA to free testosterone ratio in selecting different biology groups of prostate cancer patients

OBJECTIVES

To show that prostate cancer biology is related to serum levels of both free testosterone (FT) and prostate-specific antigen (PSA), that PSA level is linearly related to FT and that the PSA to FT ratio may be considered as the growth rate parameter expressing cancer phenotype biology.

MATERIALS AND METHODS

The study includes 135 consecutive patients diagnosed with prostate cancer. Pretreatment simultaneous serum samples for analyzing total testosterone (TT), FT and total PSA levels were obtained. The study was assessed according to a multidimensional approach of the five continuous variables including TT, FT, PSA, AGE and percentage of positive biopsies (=P+). The all sets of data were considered as one--sample with no groupings among the observations. Multivariate analysis included factor analysis (FA) and principal component analysis (PCA). Multivariate inferential statistics for comparing different groups of patients according to the PSA to free testosterone ratio (PSA/FT) included Hotteling's multivariate two-sample T²-Test for comparing two mean vectors as well as Box's M-Test with the chi-square approximation for comparing multiple covariance matrices when patients were sampled in more than two groups.

RESULTS

Factor analysis showed the two natural grouping of variables, FT-TT and PSA-P+. PCA assessed FT and PSA as the two variables with large variances having a notable influence on the first two principal components. Multiple linear regression analysis showed that all the income variables, except age, significantly predicted the PSA/FT ratio. Patients were first sampled according to the PSA/FT ratio in group 1 (PSA/FT ≤ 0.20) and group 2 (PSA/FT > 0.20), and Hotteling's multivariate two sample T²-Test was significant (P < 0.01). Patients were then sampled according to the PSA/FT ratio in group 1 (PSA/FT ≤ 0.20), group 2 (PSA/FT > 0.20 and ≤ 0.40), and group 3 (PSA/FT > 0.40), and Box's M-Test comparing the covariance matrices of the 3 groups differed significantly (P < 0.001). Finally, patients were sampled according to the PSA/FT ratio in 6 groups, and Box's M-Test was again significant (P < 0.001).

CONCLUSIONS

The PSA to FT ratio is the growing rate parameter expressing different biology patterns and assessing different groups of prostate cancer patients. In our opinion, the results of the present study might have wide applications in understanding, assessing and planning prostate cancer studies including basic science, screening, assessing risk of the disease, predicting disease stage as well natural history after a planned treatment involving biochemical recurrence, progression, hormone refractory prostate cancer and disease-specific survival.

Clinical utility of antioxidant gene expression levels in circulating cancer cell clusters for the detection of prostate cancer in patients with prostate-specific antigen levels of 4-10 ng/mL and disease prognostication after radical prostatectomy

OBJECTIVES

To test antioxidant genes (AOX) expression in circulating cancer cell clusters (CCC). A novel method using molecular, polymerase chain reaction (PCR)-based detection of CCC was applied for predicting prostate cancer and to assess the effect of radical prostatectomy (RP) on reducing CCC and for prognostication of relapse-free survival (RFS), as serum total prostate-specific antigen (tPSA) has limited specificity at 4-10 ng/mL.

PATIENTS AND METHODS

In all, 240 patients were enrolled in the study, 129 for tumour diagnosis and 111 after RP for disease prognostication. Filtration assay in previously fractionated mononuclear cells (MNC) was used to enrich the CCC and large cells, which were retained in a mesh of 20 microm width. To establish the malignant nature of these cells they were analysed for genomic imbalances detected via PCR-assays of loss of heterozygosity in tumour suppressor loci and of DNA amplification in protooncogen loci. As a screening test in daily practice, real-time reverse transcription (RT)-PCR of AOX was introduced to overcome the laborious and expensive DNA tests. The AOX chosen were glutathione peroxidase (GPX1), Mn-dependent superoxide dismutase 2 (SOD2) and thioredoxine reductase (TXNRD1); selected from 67 marker candidate genes according to sensitivity and specificity data. AOX overexpression in CCC serves as a general marker for solid tumours needing, however, organ markers to relate to the organ of origin. Androgen receptor (AR), PSA and prostate-specific membrane antigen mRNAs served as organ markers for the prostate. Signals were detected in patients' MNC and to a minor level in CCC, rendering to CCC a substantial loss in epithelial features equivalent to a lower grade of epithelial differentiation. Organ markers in the MNC fraction were positive in <85% of AOX testing.

RESULTS

The AOX test was tumour predicting (P < 0.001) with a sensitivity of 86%, specificity 82%, positive predictive value 69%, negative predictive value 92%, accuracy 83% and odds ratio (OR) of 28. SOD2 and TXNRD1 expression correlated to tumour size and Gleason score. Objective assessment for the evaluation of the molecular cell markers was achieved by receiver operating characteristic (ROC) curves. The areas under the ROC curve values of the AOXs were 0.7-0.9. RP was followed by a complete clearance of AOX-expressing cells. After RP, a subgroup of patients had residual CCC over-expressing only SOD2 and GPX1 indicating incomplete clearance by RP. Sustained overexpression of SOD2 and GPX1 accounted as risk factors for distant tumour recurrence (P = 0.003) mainly for bone metastases (97% M1b) as evaluated by Kaplan-Meier curves. In univariate analysis the tumour size had a limited effect on the probability of RFS (P = 0.05). In multivariate analysis tumour size, nodal status and Gleason score had no effect. This can partially be attributed to the higher risk level of pathological variables in the AOX over-expressing group but also to ineffective endocrine therapy resulting in marked overexpression of ARs and GPX1, the lead prognosticator gene. The AOX expression level allowed the identification of patients with high progression risk, who have more favourable pathological variables.

CONCLUSION

The AOX testing of CCC is a novel method with excellent prognostic and predictive properties enabling the monitoring of therapies, e.g. effects of RP and endocrine therapy. We speculate that the continuing elevated expression of AOX with special emphasis on GPX1 acts as survival and defence mechanism in CCC required in an atypical environment prone to escape from immune surveillance.

Prostate specific antigen for early detection of prostate cancer: longitudinal study

OBJECTIVE

To evaluate if prostate specific antigen test attains validity standards required for screening in view of recent prostate cancer screening trial results.

DESIGN

Case-control study nested in longitudinal cohort.

SETTING

Västerbotten Intervention Project cohort, Umeå, Sweden.

PARTICIPANTS

540 cases and 1034 controls matched for age and date of blood draw.

MAIN OUTCOME MEASURE

Validity of prostate specific antigen for prediction of subsequent prostate cancer diagnosis by record linkage to cancer registry.

RESULTS

Blood samples were drawn on average 7.1 (SD 3.7) years before diagnosis. The area under the curve for prostate specific antigen was 0.84 (95% confidence interval 0.82 to 0.86). At prostate specific antigen cut-off values of 3, 4, and 5 ng/ml, sensitivity estimates were 59%, 44%, and 33%, and specificity estimates were 87%, 92%, and 95%. The positive likelihood ratio commonly considered to "rule in disease" is 10; in this study the positive likelihood ratios were 4.5, 5.5, and 6.4 for prostate specific antigen cut-off values of 3, 4, and 5 ng/ml. The negative likelihood ratio commonly considered to "rule out disease" is 0.1; in this study the negative likelihood ratios were 0.47, 0.61, and 0.70 for prostate specific antigen cut-off values of 3, 4, and 5 ng/ml. For a cut-off of 1.0 ng/ml, the negative likelihood ratio was 0.08.

CONCLUSIONS

No single cut-off value for prostate specific antigen concentration attained likelihood ratios formally required for a screening test. Prostate specific antigen concentrations below 1.0 ng/ml virtually ruled out a prostate cancer diagnosis during the follow-up. Additional biomarkers for early detection of prostate cancer are needed before population based screening for prostate cancer should be introduced.

Antiangiogenic properties of prostate-specific antigen (PSA)

The prostate produces high levels of prostate-specific antigen (PSA, also known as kallikrein-related peptidase 3, KLK3), which is a potential target for tumor imaging and treatment. Although serum PSA levels are elevated in prostate cancer, PSA expression is lower in malignant than in normal prostatic epithelium and it is further reduced in poorly differentiated tumors. PSA has been shown to inhibit angiogenesis both in in vitro and in vivo models. In this review we focus on our recent studies concerning the mechanism of the antiangiogenic function of PSA. We have recently shown that the antiangiogenic activity of PSA is related to its enzymatic activity. Inactive PSA isoforms do not have antiangiogenic activity as studied by a human umbelical vein endothelial cell (HUVEC) tube formation model. Furthermore, inhibition of PSA, either by a monoclonal antibody or small molecule inhibitors abolishes the effect of PSA, while a peptide that stimulates the activity of PSA enhances the antiangiogenic effect. We have analyzed changes in gene expression associated with the PSA induced reduction of tube formation in the HUVEC model. Several small changes were observed and they were found to be opposite to those associated with tube formation. Taken together, these studies suggest that PSA exerts antiantiogenic activity related to its enzymatic activity. Thus it might be associated with the slow growth of prostate cancer.

Review of diagnostic markers for prostate cancer

This review concentrates mainly on currently available markers for prostate cancer and cannot cover the multiple marker substances which are now in experimental and clinical development. Prostate-specific antigen (PSA) is still the main diagnostic tool despite its serious limitations, which will be addressed. Studies of new diagnostic markers and also most studies of PSA are subject to attribution or assignment bias, which limits the accuracy of the resulting information. Usually a more or less arbitrarily chosen cut-off value is used as a "gold standard" to determine the indication for the decisive test, a prostatic biopsy, and the assumption is made that no cancers are present below that cut-off value. This assumption has been proved wrong by findings in the control arm of the Prostate Cancer Prevention Trial (PCPT), where more than 5,000 men were biopsied independent of their PSA status. As an example: a PSA cut-off value of4.0 ng/ml, a commonly used biopsy indicator, missed about 75% of all biopsy-detectable cancers. On the other hand, sextant biopsies in all men led to a detection rate of 21.9%, evidence of the diagnosis of many cases in men who otherwise would never have had any clinical signs of prostate cancer (overdiagnosis). The only way out of this dilemma is a better understanding of the natural history of those cases with low PSA values that would not be considered suspicious with the use of currently available risk indicator nomograms. The European Randomised Study of Screening for Prostate Cancer (ERSPC) offers such an opportunity. Results are summarised in this chapter. Evidence is provided that men diagnosed in the low PSA ranges (< 3.0 ng/ml) usually present with more favourable cancers which, when identified, are often eligible for active surveillance after application of the appropriate nomogram. In addition, the data in the setting of the ERSPC study show that biopsy in such men can safely be delayed until PSA rises to above a cut-off value of 3.0 ng/ml. The limitations of PSA discussed herein clearly point to the need to find better diagnostic and prognostic markers for prostate cancer.

Long-term assessment of prostate cancer progression free survival: evaluation of pathological parameters, nuclear shape and molecular biomarkers of pathogenesis

BACKGROUND

Molecular pathways of proliferation, angiogenesis, neuroendocrine differentiation, apoptosis and alterations in nuclear structure of cancer epithelial cells are important in the pathogenesis of prostate cancer (PCa). Therefore, we evaluated the prognostic value of these parameters in 105 clinically localized PCa tumors with long-term follow-up after radical prostatectomy for progression-free survival (PFS).

METHOD

Nuclear roundness variance (NRV) was calculated for tumor nuclei using the graphic tracing DynaCELL system. Immunohistochemistry assessed expression of Ki67, PCNA (proliferation), Chromogranin A (neuroendocrine differentiation), CD31 (angiogenesis), BCL2 (apoptosis), and Her-2/neu (oncogene) in the tumors. Cox proportional hazards regression, Spearman's rank correlation, and Kaplan-Meier plots were employed to analyze the data.

RESULTS

Gleason score, focal vs. non-focal extra-prostatic extension, organ confined status, NRV, Her-2/neu, CD-31 and Ki67 were univariately significant predictors of PFS. NRV was the most significant prognostic indicator with the highest concordance index (0.7) for PFS. Gleason score, NRV and Her-2/neu were multivariately significant and yielded a concordance index of 0.77.

CONCLUSION

Her-2/neu oncogene and NRV were shown to be significant in the prediction of PFS. The assessment of alterations in nuclear structure using NRV proved to be the most significant factor in the prediction of PFS. Integration of image analysis-based NRV and molecular biomarkers with pathologic parameters should be considered for validation in the prediction of PFS.

Combination of vitamin E and selenium causes an induction of apoptosis of human prostate cancer cells by enhancing Bax/Bcl-2 ratio

BACKGROUND

The Selenium and Vitamin E Chemoprevention Trial (SELECT) is aimed at determining the usefulness of a combination of vitamin E and selenium for Prostate cancer (PCa) prevention in humans. The aim of this study is to evaluate the efficacy and mechanistic basis of this combination.

METHODS

We determined the effect of vitamin E (+-alpha-tocopheryl succinate, VES) and selenium (methylselenic acid, MSA), alone and in combination, on the proliferation of LNCaP, DU145, and PC-3 cells as well as normal prostate PrEC cells. We also determined the involvement of Bcl-2 family proteins as a mechanism of the biological effects of vitamin E and selenium combination.

RESULTS

VES or MSA alone led to a modest inhibition in the viability and growth of PCa cells. However, a combination of these two agents resulted in a dramatic increase in growth inhibition of PCa cells. Interestingly, VES and/or MSA were not found to have any effect on the growth or viability of normal PrEC cells. VES and MSA treatment to human PCa cells resulted in (i) induction of apoptosis, (ii) increase in Bax, Bak, and Bid proteins, and (iii) decrease in Bcl-2 protein. Furthermore, Bax knockdown via shRNA and Bcl-2 overexpression via Bcl-2 plasmid resulted in a rescue of PCa cells from apoptosis.

CONCLUSIONS

Our study suggested that vitamin E and selenium combination may be more effective than either of these agents alone. Further, our data demonstrated a causal connection between Bax and Bcl-2 modulation and induction of apoptosis by VES and MSA combination.

Development of peptides specifically modulating the activity of KLK2 and KLK3

The prostate produces several proteases, the most abundant ones being kallikrein-related peptidase 3 (KLK3, PSA) and KLK2 (hK2), which are potential targets for tumor imaging and treatment. KLK3 expression is lower in malignant than in normal prostatic epithelium and it is further reduced in poorly differentiated tumors, in which the expression of KLK2 is increased. KLK3 has been shown to inhibit angiogenesis, whereas KLK2 may mediate tumor growth and invasion by participating in proteolytic cascades. Thus, it may be possible to control prostate cancer growth by modulating the proteolytic activity of KLK3 and KLK2. We have developed peptides that very specifically stimulate the activity of KLK3 or inhibit that of KLK2. Using these peptides we have established peptide-based methods for the determination of enzymatically active KLK3. The first-generation peptides are unstable in vivo and are rapidly cleared from the circulation. Currently we are modifying the peptides to make them suitable for in vivo applications. We have been able to considerably improve the stability of KLK2-binding peptides by cyclization. In this review we summarize the possible roles of KLK3 and KLK2 in prostate cancer and then concentrate on the development of peptides that modulate the activity of these proteases.

Prostate cancer

In developed countries, prostate cancer is the second most frequently diagnosed cancer, and the third most common cause of death from cancer in men. Apart from age and ethnic origin, a positive family history is probably the strongest known risk factor. Clinically, prostate cancer is diagnosed as local or advanced, and treatments range from surveillance to radical local treatment or androgen-deprivation treatment. Androgen deprivation reduces symptoms in about 70-80% of patients with advanced prostate cancer, but most tumours relapse within 2 years to an incurable androgen-independent state. The recorded incidence of prostate cancer has substantially increased in the past two decades, probably because of the introduction of screening with prostate-specific antigen, the use of improved biopsy techniques for diagnosis, and increased public awareness. Trends in mortality from the disease are less clearcut. Mortality changes are not of the same magnitude as the changes in incidence, and in some countries mortality has been stable or even decreased. The disparity between reported incidence and mortality rates leads to the probable conclusion that only a small proportion of diagnosed low-risk prostate cancers will progress to life-threatening disease during the lifetime of the patient.

Biomarkers, regerons, and pathways to lethal cancer

Cancer is a disease of "outlaw" cells that become mutated in regulatory mechanisms. They have lost normal self controls and relationships to the whole organism. Cancers can progress by several pathways from a normal cell to malignant cancer, from bad to worse. Questions about advisability of treatment for some cancers arise from the possibility that they are arrested during progression and so never become lethal. Techniques could be developed to determine the degree of progression and possibility for successful treatment. This article is intended to suggest a way of looking at cancer. It is not a review so references to research articles are infrequent.

Lung cancer screening with CT

Lung cancer is the leading cause of cancer death in the United States. Non-small cell lung cancer accounts for 75% to 80% of all lung cancers. There is an impetus to find a screening test that can detect non-small cell lung cancer in its early preclinical stages, when surgical resection is most likely to reduce lung cancer mortality. Although earlier randomized controlled trials of lung cancer screening using chest radiography and sputum cytology failed to show reduced lung cancer mortality, CT is a much more sensitive test for detecting small lung nodules, and has generated considerable enthusiasm as a potential contemporary screening tool for lung cancer.

The cancer incidence temporality index: An index to show temporal changes in the age of onset of overall and specific cancer (England and Wales, 1971–1999)

The theory that increasing cancer incidence rates in developed countries are primarily the consequence of an expanding ageing population and improved diagnostic testing is widely held. In the United Kingdom the proportion of people aged 50 and over has increased by 45% since 1951 and this proportion is set to increase by a further 36% by the year 2031, so the United Kingdom does indeed have an expanding ageing population. However, the increase in cancer incidence affects people across the whole age spectrum. To test the hypothesis that the age of onset of cancer (overall and specific) in England and Wales is decreasing over time we have developed The Cancer Incidence Temporality Index (CITI), which gives a crude measurement of the portion of the population, in which cancer incidence is rising fastest over time: I=(SigmaO(a)/ SigmaE(a))/(SigmaO(a)/SigmaE(a)), where I is the CITI value, O is the observed number of cases and E is the expected number of cases; 'a' and 'b' refer to separate summation ranges for younger and older age groups. Population data and cancer incidence data in England and Wales, 1971-1999 were obtained from the UK Office for National Statistics. The trends in CITI values have been shown graphically for cancer overall and for specific tumour sites. The impact of diagnostic testing is also addressed. The results of this study suggest that the average age of onset of prostate, breast and cervical cancer is temporally decreasing. The study also suggests that for cancer overall the trend for the age of onset of cancer in males has stabilised since 1990 and has started to reverse in females from 1995 despite the expanding ageing population. A similar trend is observed for leukaemias. The CITI analysis for colon cancer shows that the age of onset in both males and females is increasing over time. The trend for ovarian cancer is similar to that for colon cancer. The CITI analysis for NHL in males is similar to that for colon cancer, however, in females the trend stabilised after 1990. The CITI may aid prediction of changes in the age of onset of cancer and thus aid targeted aetiological research. In addition, we suggest the need for a mathematical model, which may measure the changes in the age of onset of cancer in units of time.

Lifestyle-related factors and environmental agents causing cancer: an overview

The increasing incidence of a variety of cancers after the Second World War confronts scientists with the question of their origin. In Western countries, expansion and ageing of the population as well as progress in cancer detection using new diagnostic and screening tests cannot fully account for the observed growing incidence of cancer. Our hypothesis is that environmental factors play a more important role in cancer genesis than it is usually agreed. (1) Over the last 2-3 decades, alcohol consumption and tobacco smoking in men have significantly decreased in Western Europe and North America. (2) Obesity is increasing in many countries, but the growing incidence of cancer also concerns cancers not related to obesity nor to other known lifestyle-related factors. (3) There is evidence that the environment has changed over the time period preceding the recent rise in cancer incidence, and that this change, still continuing, included the accumulation of many new carcinogenic factors in the environment. (4) Genetic susceptibility to cancer due to genetic polymorphism cannot have changed over one generation and actually favours the role of exogenous factors through gene-environment interactions. (5) Age is not the unique factor to be considered since the rising incidence of cancers is seen across all age categories, including children, and adolescents. (6) The fetus is specifically vulnerable to exogenous factors. A fetal exposure during a critical time window may explain why current epidemiological studies may still be negative in adults. We therefore propose that the involuntary exposure to many carcinogens in the environment, including microorganisms (viruses, bacteria and parasites), radiations (radioactivity, UV and pulsed electromagnetic fields) and many xenochemicals, may account for the recent growing incidence of cancer and therefore that the risk attributable to environmental carcinogen may be far higher than it is usually agreed. Of major concern are: outdoor air pollution by carbon particles associated with polycyclic aromatic hydrocarbons; indoor air pollution by environmental tobacco smoke, formaldehyde and volatile organic compounds such as benzene and 1,3 butadiene, which may particularly affect children and food contamination by food additives and by carcinogenic contaminants such as nitrates, pesticides, dioxins and other organochlorines. In addition, carcinogenic metals and metalloids, pharmaceutical medicines and some ingredients and contaminants in cosmetics may be involved. Although the risk fraction attributable to environmental factors is still unknown, this long list of carcinogenic and especially mutagenic factors supports our working hypothesis according to which numerous cancers may in fact be caused by the recent modification of our environment.

Tissue and serum levels of principal androgens in benign prostatic hyperplasia and prostate cancer

Androgens are considered to play a substantial role in pathogenesis of both benign prostatic hyperplasia (BPH) and prostate cancer. The importance of determination of androgen levels in tissue and serum for cancer progression and prognosis has been poorly understood. The aim of study was to find out hormonal differences in both diseases, their correlations between intraprostatic and serum levels and predicted value of their investigation. Testosterone, dihydrotestosterone, androstenedione and also epitestosterone were determined in prostate tissue from 57 patients who underwent transvesical prostatectomy for BPH and 121 patients after radical prostatectomy for prostate cancer. In 75 subjects with cancer and 51 with BPH the serum samples were analyzed for testosterone, dihydrotestosterone and SHBG. Significantly higher intraprostatic androgen concentrations, i.e. 8.85+/-6.77 versus 6.44+/-6.43 pmol/g, p<0.01 for dihydrotestosterone, and 4.61+/-7.02 versus 3.44+/-4.53 pmol/g, p<0.05 for testosterone, respectively, were found in patients with prostate cancer than in BPH. Higher levels in cancer tissue were found also for epitestosterone. However, no differences were found in serum levels. Highly significant correlations occurred between all pairs of intraprostatic androgens and also epitestosterone as well as between serum testosterone and dihydrotestosterone (p<0.001) in both BPH and cancer groups. Correlation was not found between corresponding tissue and serum testosterone and dihydrotestosterone, either in benign or cancer samples. The results point to importance of intraprostatic hormone levels for evaluation of androgen status of patients, contrasting to a low value of serum hormone measurement.

Incidental diagnosis of a PSA-negative prostate cancer by 18FDG PET/CT in a patient with hypopharyngeal cancer

Diagnosis of prostate cancer (PC) still remains critical as non-invasive screening with prostate specific-antigen (PSA) lacks to indicate malignancy of the prostate in some cases. Recent research has shown that clinically meaningful PC can develop in patients with a PSA value <4 ng/ml, frequently defined as upper limit of normal serum PSA levels. Furthermore, both morphological (computed tomography (CT), magnetic resonance imaging, transrectal ultrasound) and functional imaging with (18)fluorodeoxyglucose positron emission tomography (FDG-PET) are associated with several limitations for primary diagnosis of PC. We report a case of an incidentally diagnosed PSA-negative PC by (18)FDG PET/CT in a patient with a previous diagnosis of a hypopharyngeal cancer.

Improved prostate cancer detection with a human kallikrein 11 and percentage free PSA-based artificial neural network

Human kallikrein 11 (hK11) was evaluated in a percentage free PSA-based artificial neural network (ANN) to reduce unnecessary prostate biopsies. Serum samples from 357 patients with (n=132) and without (n=225) prostate cancer (PCa) were analyzed and ANN models were constructed and compared to all parameters. The discriminatory power of hK11 was lower than that of PSA, but receiver operator characteristic (ROC) analyses demonstrated significantly larger areas under the curves for the ANN compared to all other parameters. ANNs with hK11 may lead to a further reduction in unnecessary prostate biopsies, especially when analyzing patients with less than 15% free PSA.

Novel peptide inhibitors of human kallikrein 2

Human kallikrein 2 (hK2) is a serine protease produced by the secretory epithelial cells in the prostate. Because hK2 activates several factors participating in proteolytic cascades that may mediate metastasis of prostate cancer, modulation of the activity of hK2 is a potential way of preventing tumor growth and metastasis. Furthermore, specific ligands for hK2 are potentially useful for targeting and imaging of prostate cancer and for assay development. We have used enzymatically active recombinant hK2 captured by a monoclonal antibody exposing the active site of the enzyme to screen phage display peptide libraries. Using libraries expressing 10 or 11 amino acids long linear peptides, we identified six different peptides binding to hK2. Three of these were shown to be specific and efficient inhibitors of the enzymatic activity of hK2 toward a peptide substrate. Furthermore, the peptides inhibited the activation of the proform of prostate-specific antigen by hK2. Amino acid substitution analyses revealed that motifs of six amino acids were required for the inhibitory activity. These peptides are potentially useful for treatment and targeting of prostate cancer.