Prostate-specific antigen (PSA) in the management of 500 prostatic patients

17beta-Estradiol differentially regulates androgen-responsive genes through estrogen receptor-beta- and extracellular-signal regulated kinase-dependent pathways in LNCaP human prostate cancer cells

The molecular mechanism underlying the actions of estrogens in normal prostate physiology and prostate cancer development remains unclear. In the present study we tested the hypothesis that estrogens modulate androgen-dependent events in prostate cells by examining the effects of 17beta-estradiol (E2) on androgen-responsive genes (ARGs) in the androgenresponsive LNCaP cells. We found that LNCaP cells express estrogen receptor-beta (ER-beta) as the major form of ER and ER treatment with E2 led to an increase in cell growth. The proliferative effect of E2 correlated with induction of several ARGs by E2. Interestingly, some other ARGs did not respond to E2. Consistent with involvement of ER-beta, the induction of both cell growth and ARG mRNA levels by E2 was attenuated by the pure antiestrogen ICI 182,780. Moreover, we found ER-beta small interfering RNA attenuated induction of ARG mRNAs by E2. However, the effect of E2 on ARG mRNA appeared also to require the androgen receptor and to be mediated through activation of the extracellular-signal regulated kinase (ERK) pathway. These results provide mechanistic evidence supporting a direct effect of estrogen, mediated through ER-beta- and ERK-dependent pathways, on specific molecular targets in human prostate cancer cells.

Surrogate tissue analysis: monitoring toxicant exposure and health status of inaccessible tissues through the analysis of accessible tissues and cells

Genomics and proteomics have made it possible to define molecular physiology in exquisite detail, when tissues are accessible for sampling. However, many tissues are not accessible for human diagnostic evaluations or experimental studies, creating the need for surrogates that afford insight into exposures and effects in such tissues. Surrogate tissue analysis (STA) incorporating contemporary genomic and proteomic technologies may be useful in determining toxicant exposure and effect, or disease state, in target tissues at the pre- or early clinical stage. We present here a discussion of STA based on presentations given at the Society of Toxicology's 2003 annual meeting's "Innovations in Applied Toxicology" symposium. Speakers at the symposium (Box 1) discussed various potential applications of STA, including the use of peripheral blood lymphocytes (PBLs) as a source of genetic biomarkers to monitor radiation exposure; the use of gene expression analysis of PBLs and hair follicles as a means to monitor the impact of toxicants on inaccessible organs; the characterization of disease-associated gene signatures in peripheral blood mononuclear cells (PBMCs) of renal cell carcinoma (RCC) patients; the use of sperm RNA to determine genetic and environmental effects on sperm development in the testis; and the use of serum protein profiles to monitor the development and progression of various cancers. Also discussed are some of the challenges that must be overcome if the utility of STA is to be proven, and thus permit researchers to move this concept from the laboratory to the clinical environment.

Prostate-specific antigen in mass screening for carcinoma of the prostate

BACKGROUND

Prostate-specific antigen (PSA) has various advantages over prostatic acid phosphatase (PAP) as a marker for prostate cancer, but its role in prostate cancer mass screening remains controversial. We measured serum PSA in addition to serum PAP determination and digital rectal examination (DRE) in our mass screening program to assess the usefulness of PSA for prostate cancer mass screening.

METHODS

Serum PSA and PAP measurements and DRE were performed in 1249 patients in mass screening for carcinoma of the prostate in 1989 and 1990. Thirteen cancers were diagnosed. We calculated the mean plus standard deviations (2SD) of the PSA and PAP values of men without cancer, and assessed the usefulness of PSA for prostate cancer screening by using these figures as the upper limit of normal.

RESULTS

The number positive for PSA, PAP and DRE were 39, 36 and 48, respectively. If our screening had been performed without DRE, three cancers would have remained undetected, and the number would have been the same if performed without PSA. If the screening had been performed without PAP, on the other hand, no cancers would have remained undetected. The sensitivities of PSA and PAP were 54% and 23%, respectively. The screening detection rate with DRE and PSA was 0.88%, and with DRE and PAP was 0.64%.

CONCLUSIONS

Measurement of serum PSA values with adjustment of the cut-off value was considered more useful than PAP in mass screening for prostate cancer.

Altered saccharide sequences in two groups of patients with metastatic prostatic carcinoma

OBJECTIVE

To investigate the hypothesis that primary prostatic carcinomas with metastases to different sites (lymph nodes or bone) show varying expression of cell surface and cytoplasmic glycoconjugates.

PATIENTS AND METHODS

A group of 14 patients with primary prostatic carcinoma with lymph node metastases but no bone metastases has previously been shown to have an increased survival time. This group was compared with a control group of 14 patients with lymph node-negative, bone metastasis-positive primary prostatic carcinoma using a panel of biotinylated lectins revealed by the avidin-biotin peroxidase complex method. The results were analysed semi-quantitatively and differences in binding patterns between the two groups were sought.

RESULTS

No significant differences were seen using the LCA, LTA, UEA-1, WFA, VVA or SBA lectins. The group with bone metastases but no lymph node involvement showed significantly increased binding for the ECA and AHA lectins, both before and after neuraminidase pre-treatment, compared with the lymph node-positive group.

CONCLUSIONS

These results suggest that tumours lacking or having a reduced affinity for binding sites for both Gal beta 1-3GalNac (Type I oligosaccharide structures--AHA) and Gal beta 1-4GlcNac (Type II oligosaccharide structures--ECA) sequences are more likely to develop lymph node metastases and less likely to develop bone metastases and thereby increasing the patient's chances of survival. This is further evidence that the metastatic potential of tumours per se and the ultimate site of distal metastases from such tumours is affected in part by the glycoconjugates expressed on their cell surfaces and indicates that metastatic phenotypes for prostatic carcinoma exists.

Analysis of variation in prostate-specific antigen values

This retrospective study analyzes variation in prostate-specific antigen (PSA) levels in 129 males who were not diagnosed with prostate cancer or other known malignancies. The extent to which the assay and the biologic variation contributed to the variation in PSA concentration was evaluated from analysis of slopes characterizing PSA concentration as a function of time. The mean coefficient of variation on observations was 58.0 percent. The estimated mean biologic coefficient of variation was 55.3 percent versus a mean assay coefficient of variation of 13.2 percent, indicating that the assay variation contributed negligibly to variation compared with the biologic variation. The concept that a PSA level which rises more than that attributable to assay variation indicates the need for invasive testing for prostate cancer is questionable. A decreasing PSA level was seen as often and of the same magnitude as an increasing level within a relatively narrow window of approximately one year. We are aware of no reason why this variability in PSA values would not be observed in patients with occult prostate cancer.