PSA immunoreactivity detected in LNCaP cell medium, breast tumor cytosol, and female serum

Pharmacological characterization of an imidazolopyrazole as novel selective androgen receptor modulator

Selective androgen receptor modulators (SARMs) are androgens with tissue-selective activity. SARMs that have anabolic activity on muscle while having minimal stimulatory activity on prostate are classified as SARM agonists. They can be used to prevent the loss of lean body mass that is associated with cancer, immunodeficiency, renal disease and aging. They may also have anabolic activity on bone; thus, unlike estrogens, they may reverse the loss of bone strength associated with aging or hypogonadism. Our in-house effort on SARM program discovers a nonsteroidal androgen receptor ligand with a unique imidazolopyrazole moiety in its structure. In vitro, this compound is a weak androgen receptor binder and a weak androgen agonist. Despite this, in orchidectomized mature rats it is an effective SARM agonist, with an ED(50) on levator ani muscle of 3.3mg/kg and an ED(50) on ventral prostate of >30mg/kg. It has its maximal effect on muscle at the dose of 10mg/kg. In addition, this compound has mixed agonistic and antagonistic activities on prostate, reducing the weight of that tissue in intact rats by 22% at 10mg/kg. The compound does not have significant effect on gonadotropin levels or testosterone levels in both orchidectomized and intact male rats. It does not have notable progestin, estrogen or glucocorticoid agonistic or antagonistic activity in rats. In a female sexual behavior model, it improves the sexual desire of ovariectomized female rats for sexually mature intact males over nonsexually ovariectomized females. Overall, the imidazolopyrazole is a potent prostate-sparing candidate for development as a SARM agonist with an appropriate pharmacological profile for clinical benefit in muscle-wasting conditions and female sexual function disorders.

The diagnostic and prognostic utility of prostate-specific antigen for diseases of the breast

Although prostate-specific antigen (PSA) is the most valuable tumor marker for the diagnosis and management of prostate carcinoma, it is widely accepted that PSA is not prostate specific. Numerous studies have shown that PSA is present in some female hormonally regulated tissues, principally the breast and its secretions. In this review, we summarize the findings of PSA in the breast, and focus on its potential for clinical applications in breast disease. PSA is produced by the majority of breast tumors and is a favorable indicator of prognosis in breast cancer. Low levels of PSA are released into the female circulation, and while the level of serum PSA is elevated in both benign and malignant breast disease, the molecular form of circulating PSA differs between women with and without breast cancer. These findings indicate that PSA may have potential diagnostic utility in breast cancer. PSA may also have a clinical application in benign breast disease, as both the level and molecular form of PSA differ between Type I and II breast cysts. High levels of PSA have been reported in nipple aspirate fluid (NAF) and recent studies have shown that the concentration of PSA in NAF is inversely related to breast cancer risk, indicating that NAF PSA may represent a clinical tool for breast cancer risk assessment. Thus, PSA represents a marker with numerous potential clinical applications as a diagnostic and/or prognostic tool in breast disease.

Measurement of prostate-specific antigen in detection of benign or malignant breast disease in women

Using a highly sensitive chemiluminescent enzyme immunoassay, we have evaluated the measurement of serum prostate-specific antigen (PSA) as a potential diagnostic test for differentiation between women with breast cancer and those with benign breast disease. In a controlled study consisting of 284 women with well-documented patient files and matched for age and long-term place of residence, serum samples collected from 90 women with histologically confirmed breast cancer, 94 women with benign breast disease and 100 controls were analysed. Serum total PSA levels in benign breast disease and cancer patients are not statistically different from those of healthy controls. Total PSA levels decrease with age in normal controls and breast cancer patients but not in those with benign breast disease. The total PSA concentration decreases after menopause in healthy women, though not in patients with breast cancer or benign breast disease. Total PSA bore no relation to the histological type or grade of the tumour or the disease stage of the breast cancer patients. In benign breast disease, all mastopathy patients had normal total PSA, whereas elevation of the values was observed in 7% of fibroadenoma patients. Our results show that serum total PSA cannot be used to distinguish between healthy women and/or women with breast cancer or benign breast disease.

Prostate-specific antigen and gross cystic disease fluid protein-15 are co-expressed in androgen receptor-positive breast tumours

Androgens regulate breast cancer cell proliferation via androgen receptor (AR)-mediated mechanisms. To investigate further the androgen-responsiveness of human breast tumours, we examined the immunohistochemical expression of the AR and two androgen-regulated proteins, prostate-specific antigen (PSA) and gross cystic disease fluid protein-15 (GCDFP-15), in 72 primary breast tumours. AR immunoreactivity was present in the nuclei of breast tumour cells and was correlated with oestrogen receptor (ER; P < 0.05) and progesterone receptor (PR; P < 0.01) status. PSA and GCDFP-15 immunoreactivity was present in the cytoplasm of tumour cells but not the adjacent stromal cells. AR-positive cells were present in 85% (61/72) of breast tumours, and 98% (43/44) of PSA-positive and 92% (44/48) of GCDFP-15-positive tumours were also positive for AR. Positive immunoreactivity for both PSA and GCDFP-15 in breast tumours was highly dependent on AR status (odds ratios of 24.0 and 4.5 respectively), but unrelated to age, ER and PR status and axillary lymph node involvement. PSA immunoreactivity was more frequently observed in moderate and well-differentiated tumours and was significantly (P < 0.001) associated with GCDFP-15 immunoreactivity. In conclusion, PSA and GCDFP-15 immunoreactivity was dependent on the presence of AR, but not ER or PR in primary breast tumours.

LNCaP produces both putative zymogen and inactive, free form of prostate-specific antigen

BACKGROUND

Our objective was to investigate the presence of prostate specific antigen (PSA) and alpha-1-antichymotrypsin (ACT) mRNA and protein in prostate cancer cell lines, and the complexing characteristics of expressed PSA.

METHODS

RT-PCR, immunohistochemistry, and Western blots were employed. Trypsin treatment of PSA was performed to establish the possible presence of an activatable form of PSA.

RESULTS

ACT mRNA and protein were detected in LNCaP, PC-3, and DU 145 by RT-PCR and by immunohistochemistry, respectively. Only LNCaP cells were positive for PSA mRNA and protein. LNCaP expressed approximately 30% active PSA, approximately 40% putative zymogen form of PSA, and approximately 30% stably inactive PSA.

CONCLUSIONS

We have shown that the majority of PSA expressed by LNCaP cells is present in free, noncomplexed forms in the conditioned media. A portion (40%) can be activated by trypsin, while the rest is stably inactive PSA. LNCaP cells may serve as a source of the "unreactive" PSA present in prostate cancer patients' serum.

Prostate-specific antigen expression in a case of intracystic carcinoma of the breast: characterization of immunoreactive protein and literature surveys

A case is presented of female breast intracystic carcinoma with prostate-specific antigen (PSA) expressed in high amounts in aspirated cystic fluid (55 μg/L). Tumor extract analysis revealed the presence of both estrogen and progesterone receptors (0.38 and 1.87 nmol/L, respectively) and high quantities of PSA too (19.52 μg/L). Chromatographic analysis of cystic fluid revealed two peaks of PSA, at the expected positions for free and bound serine protease. A major proportion of 33-kDa free form was also confirmed by Western blotting analysis. Free PSA was heat-stable at 56 °C and displayed no change after freezing–thawing. These findings are discussed in the context of a detailed literature survey. Our data support the contention that PSA immunoreactivity in intracystic fluid of breast carcinoma is partly the result of secretory activity by the neoplastic cells and that the steroid receptors can also modulate its expression.