Donald J.A. Sutherland

Immunoreactive prostate-specific antigen levels in female and male breast tumors and its association with steroid hormone receptors and patient age

Prostate-specific antigen (PSA) is believed to be a highly specific marker for normal or cancerous prostatic tissue. We recently found that immunoreactive PSA (IR-PSA) is present in 30% of breast tumor cytosols (from 525 breast cancer patients). In this paper we analyzed a new series of 750 breast tumor cytosols, obtained from 744 women and six men, for IR-PSA. The positivity rates in the old and new series were very similar (approximately 30%). Combining the two series of breast cancer patients, we examined the associations between IR-PSA and estrogen (ER) or progesterone (PR) receptors, or patient age. We found that IR-PSA positivity rate declines with age. PSA-positive tumors were highly associated with either ER-positive or PR-positive tumors alone. However, analysis in a subset of tumors that combine the two receptors, ER(-)/PR(-), ER(+)/PR(-), ER(-)/PR(+), and ER(+)/PR(+), revealed that IR-PSA was only associated with PR, and no relationship was found between IR-PSA and ER. We speculate that the presence of IR-PSA in breast cancer may be associated with the PR action and that the association between PSA and ER is indirect due to the known association between ER and PR. As five of the six male breast tumors were found negative for IR-PSA, it is suggested that androgen may not be involved in the presence of IR-PSA in breast tumor.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of prostate-specific antigen immunoreactivity in breast tumors

Prostate-specific antigen (PSA) is a glycoprotein produced by the epithelial cells of the prostate. PSA is currently used in clinical practice to facilitate diagnosis and monitoring of prostate carcinoma. The prostate is an organ that possesses androgen, estrogen, and progesterone receptors, and in this respect is similar to the breast. We postulated that breast tumors might also have the ability to produce PSA. We performed these studies on a collection of 525 tumor specimens collected for routine biochemical determination of estrogen and progesterone receptors. Using a highly sensitive immunofluorometric procedure, we measured the p53 tumor suppressor gene product and PSA. Twenty nine percent of the breast tumor extracts contained detectable levels of PSA immunoreactivity (> 0.05 µg/L). The immunoreactive PSA content was associated with estrogen and/or progesterone receptor-positive tumors (P < 0.002). No association was found between PSA immunoreactivity and levels of the p53 tumor suppressor gene product (P = 0.37). High performance liquid chromatography and Western blot analysis revealed that the PSA immunoreactivity in the tumor had a molecular weight of 30 kDa, similar to that of seminal PSA. Immunoreactive PSA-positive tumors were associated with younger women (P = 0.012) and earlier disease stage (P = 0.064). We postulate that PSA immunoreactivity may be an additional marker of steroid hormone receptor-ligand action.

Phase I/II Trial of Metronomic Chemotherapy With Daily Dalteparin and Cyclophosphamide, Twice-Weekly Methotrexate, and Daily Prednisone As Therapy for Metastatic Breast Cancer Using Vascular Endothelial Growth Factor and Soluble Vascular Endothelial Growth Factor Receptor Levels As Markers of Response

PURPOSE Preclinical studies indicate that metronomic chemotherapy is antiangiogenic and synergistic with other antiangiogenic agents. We designed a phase I/II study to evaluate the safety and activity of adding dalteparin and prednisone to metronomic cyclophosphamide and methotrexate in women with measurable metastatic breast cancer (MBC). PATIENTS AND METHODS Patients received daily dalteparin and oral cyclophosphamide, twice-weekly methotrexate, and daily prednisone (dalCMP). The primary study end point was clinical benefit rate (CBR), a combination of complete response (CR), partial response (PR), and prolonged stable disease for > or = 24 weeks (pSD). Secondary end points included time to progression (TTP), duration of response, and overall survival (OS). Biomarker response to treatment was assessed by using plasma vascular endothelial growth factor (VEGF) and soluble VEGF receptors (sVEGFRs) -1 and -2. Results Forty-one eligible patients were accrued. Sixteen (39%) had no prior chemotherapy for MBC; 15 (37%) had two or more chemotherapy regimens for MBC. Toxicities were minimal except for transient grade 3 elevation of liver transaminases in 11 patients (27%) and grade 3 vomiting in one patient (2%). One patient (2%) had CR, six (15%) had PR, and three (7%) had pSD, for a CBR of 10 (24%) of 41 patients. Median TTP was 10 weeks (95% CI, 8 to 17 weeks), and median OS was 48 weeks (95% CI, 32 to 79 weeks). VEGF levels decreased but not significantly, whereas sVEGFR-1 and -2 levels increased significantly after 2 weeks of therapy. There was no correlation between response and VEGF, sVEGFR-1, or sVEGFR-2 levels. CONCLUSION Metronomic dalCMP is safe, well tolerated, and clinically active in MBC.

Carcinoembryonic antigen in breast cancer.

Carcinoembryonic antigen (CEA) levels were determined in 742 postoperative patients with breast cancer. Within this group the percentage of elevated (≥ 4.0 ng/ml) assays increased with UICC clinical stage and was 14.8% (12/81), 23.7% (27/114), 73.1% (190/260) and 20.0% (49/245) for stages I, 11, 111, IV and X (unstagable due to insufficient data) patients. We have now followed the above 482 stages I, II, III and X patients in whom CEA was performed ≤3 months after initial surgery at a time when there was no evidence of residual disease, for an average interval of 255 days from date of diagnosis. At present 16.2% (17/105) of patients with elevated CEA values compared to only 4.8% (18/377) of patients with normal values have developed recurrent disease (p < .0005). There is an association of elevation of CEA postoperatively with different clinical stages of breast cancer. Elevated CEA levels postoperatively are associated with an increased risk of development of recurrent disease in breast cancer patients.

Expression of a prostate-associated protein, human glandular kallikrein (hK2), in breast tumours and in normal breast secretions.

The recent demonstration of human glandular kallikrein (hK2) expression in a breast carcinoma cell line has suggested that this putatively prostate-restricted, steroid hormone-regulated protease may also be expressed in breast epithelium in vivo and secreted into the mammary duct system. Given that the only substrate yet identified for hK2 activity is the precursor of prostate-specific antigen (PSA), the expression of which in breast carcinomas may be associated with favourable prognosis, our purpose was to examine the expression pattern of both hK2 and PSA in breast tumour tissues. Cytosolic extracts of 336 primary breast carcinomas prepared for routine oestrogen receptor (ER) and progesterone receptor (PR) analysis, as well as 31 nipple aspirates from six women with non-diseased mammary glands, were assayed for hK2 and PSA using immunofluorometric assays developed by the authors. In the tumour extracts, measurable hK2 and PSA concentrations were detected in 53% and 73% of cases respectively, and were positively correlated to each other (r = 0.59, P = 0.0001). Higher concentrations of PSA and hK2 were found in tumours expressing steroid hormone receptors (P = 0.0001 for PSA and P = 0.0001 for hK2, by Wilcoxon tests for both ER and PR), and both PSA (r = 0.25, P = 0.0001) and hK2 (r = 0.22, P = 0.0001) correlated directly with PR levels. A negative correlation between patient age and PSA (r = –0.12, P = 0.03) was also found. Both proteins were present in nipple aspirate fluid at relatively high concentrations which were positively correlated (r = 0.53, P = 0.002). The molecular weights of the immunoreactive species quantified by the hK2 and PSA assays were established by high-performance liquid chromatography (HPLC) and were consistent with the known molecular weights of hK2 and PSA. Together these data provide the first evidence, to our knowledge, that both malignant breast tissue and normal breast secretion contain measurable quantities of hK2, and that the degree of hK2 expression or secretion is directly proportional to the expression of PSA and steroid hormone receptors. hK2 expression may therefore be a marker of steroid hormone action in breast tissue.

A randomized crossover trial of tamoxifen versus ovarian ablation for metastatic breast cancer in premenopausal women: A report of the National Cancer Institute of Canada Clinical Trials Group (NCIC CTG) trial MA.1

We concluded a randomized crossover trial comparing tamoxifen 40 mg daily with ovarian ablation for treatment of metastatic breast cancer in premenopausal women. Objective responses (complete response (CR) plus partial response (PR)) were observed in 5/20 patients treated initially with tamoxifen and in 3/19 patients initially treated with ovarian ablation (p=0.69). Seven additional patients were stable (SD) on tamoxifen while five additional patients were stable after ovarian ablation, for CR + PR + SD rates of 12/20 (60%) for tamoxifen and 8/19 (42%) for ovarian ablation (p=0.34). Median time to disease progression was 184 days for tamoxifen and 126 days for ovarian ablation (p=0.40, logrank test, odds ratio for progression 0.71). Overall survival times were also similar: a median of 2.35 years for tamoxifen and 2.46 years for ovarian ablation (p=0.98, logrank test, odds ratio for death 1.07). Side effects from tamoxifen included hot flashes and menstrual abnormalities. With one exception, these toxicities were not sufficient to require dose reduction. In this small study, tamoxifen was associated with similar response rates, response durations, and survival times to those observed with ovarian ablation.

Androgen receptors: Relationship to growth response and to intracellular androgen transport in nine variant lines of the shionogi mouse mammary carcinoma

Aspects of the biological significance of androgen receptors have been studied in nine variant lines of the Shionogi carcinoma, two of which are androgen dependent and seven of which are autonomous. The dependent lines, and two of the seven autonomous lines, contain androgen receptors; this finding demonstrates that the presence of receptors is not an accurate marker of hormonal dependence in vivo. Since the ability to transport androgens into the nucleus, as judged from the relative maximal rates of transport, is virtually restricted to dependent and autonomous lines which possess cytoplasmic receptors, it is clear that such receptors may play a role in regulating the intranuclear concentration of androgens. The absence of cytoplasmic receptors and the comparative lack of perceptible transfer of androgens across the nuclear membrane are features peculiar to the autonomous condition.

Breast cancer prognostic significance of a single nucleotide polymorphism in the proximal androgen response element of the prostate specific antigen gene promoter

Prostate Specific Antigen (PSA) expression by breast epithelial cells is associated with favorable breast cancer prognosis. In preliminary studies, we found that a nucleotide variation (G → A) at position −158 in the androgen response element (ARE-1) of the PSA promoter was present in four out of 9 breast tumors examined and in a breast carcinoma cell line. We have now determined the nucleotide composition at position −158 of DNA extracted from 148 well-characterized breast tumors and compared tumor genotype with that of controls without cancer, with tumor PSA concentration and with clinicopathological variables, overall survival and disease free survival. The G → A base change at position −158 is a polymorphism. Allelotypes were similarly distributed in breast cancer patients and controls. The Mann–Whitney U Test showed a significantly higher tumor PSA concentration in tumors that presented a homozygous G as opposed to homozygous A genotype. Genotype at position −158 was not associated with clinicopathological variables in contingency table analysis. Univariate Cox regression models showed a 28% reduction in risk for death in patients with homozygous G genotype compared to those with homozygous A genotype (P=0.03). However, ARE-I genotype did not significantly add to the prognostic power in the multivariate model of overall survival. In summary, the base change at position −158 is a polymorphism that may affect breast cancer prognosis, but further studies are required to confirm this possibility and to investigate the relevance of this polymorphism in terms of breast cancer susceptibility.

Quantification of creatine kinase BB isoenzyme in tumor cytosols and serum with an ultrasensitive time-resolved immunofluorometric technique.

OBJECTIVES To develop a highly sensitive immunofluorometric procedure for creatine kinase BB isoenzyme and use it to measure CK-BB in tumor cytosolic extracts and serum of cancer patients and healthy volunteers. DESIGN AND METHODS For assay development, we used two monoclonal antibodies in combination with time-resolved fluorometry and the biotin-avidin system. We measured CK-BB in breast tumor cytosols and studied its association with steroid hormone receptors. We also measured CK-BB in the serum of healthy subjects and patients with prostate cancer. We have examined the molecular weight of CK-BB in serum using high performance liquid chromatography. RESULTS The evaluation of the method revealed good precision and accuracy. Study of 336 breast tumor cytosols and 9 normal breast cytosols has shown that CK-BB is overexpressed by 95% of breast tumors and that CK-BB is present in its 80 kDa form. A close association between CK-BB and estrogen but not progesterone receptors was found, suggesting that CK-BB overexpression is another marker of estrogen sensitivity of these tumors. Previous studies, using CK-BB radioimmunoassay could not detect CK-BB in the serum of about 50% of healthy subjects. We have assessed CK-BB levels in 80 male volunteers, detected CK-BB in all sera and provided a detailed distribution of values. We further demonstrated that 30% of prostate cancer patients in remission (PSA < 0.4 microgram/L) post radical prostatectomy and 50% of patients with active prostate cancer (PSA > 20 microgram/L) have elevated serum CK-BB levels. The patients with highly elevated CK-BB also had highly elevated serum PSA. We have demonstrated that some patients who have elevated serum CK-BB also have macromolecular CK complexes in their serum with molecular weights of 700 and 350 kDa as well as the 80 kDa CK-BB isoenzyme. Only the latter was recognized by the assay developed. CONCLUSIONS CK-BB is a marker of estrogen sensitivity in breast cancer; Patients with prostate cancer have elevated CK-BB in their serum; The new highly specific and sensitive assay may be further used to study the role of CK-BB in various malignancies.

The standardization of estrogen receptors

Tumour estrogen receptor (ER) status may determine the medical treatment of a patient with breast cancer; yet inter-laboratory results can vary markedly, particularly when absolute cut-offs in fmol/mg cytosol protein are used. The use of standardized log units is proposed to permit greater inter-laboratory comparability. We have assessed the biochemical ER values using the dextran-coated charcoal method with three data sets, two quality control (QC) sets for Ontario laboratories and a data set with values for 184 primary breast cancer patients seen at Womens College Hospital (WCH) between 1985 and 1986. The distributions for all the raw data were skewed toward the lower end of the range; a log transformation improved the symmetry of the distributions. There was marked inter-laboratory variation in the QC data, and standardized log units greatly reduced this variability. The WCH data had similar differentiation by tumour size and nodal status with both the raw data and standardized log units. However, standardized log units provided more consistent evidence of an association between ER and immunohistochemical ERICA. The standardized log units provide quantitative receptor values suitable for multi-centre research, for future work with clinical outcomes, and for the daily management of patients.