Apoptosis during breast carcinoma progression.
(9/3862)
The purpose of this study was to investigate apoptosis, proliferation, and the expression of apoptosis-influencing proteins bcl-2 and bax and estrogen and progesterone receptors during breast carcinoma progression. The material consisted of 53 paired breast carcinoma samples representing primary and recurrent tumors and 24 control samples. The recurrent sample was located either in the breast scar tissue or at a distant metastatic site. Apoptosis was detected both morphologically and by 3' end labeling of fragmented DNA. Cell proliferation was evaluated immunohistochemically by the MIB index. The expressions of bcl-2, bax, and estrogen and progesterone receptors were studied immunohistochemically. There was a significant increase in the extent of apoptosis and proliferation in recurrent tumors compared to the primary lesions (P = 0.015 and P = 0.038, respectively). In primary tumors with an apoptotic index of >0.50%, the survival of the patients was significantly shorter (P = 0.015). In cases with a significant increase in apoptosis or proliferation in the recurrent tumor, the survival of the patients was significantly shorter (P = 0.009 and P = 0.003, respectively). Of the variables analyzed, bcl-2 expression and a positive estrogen receptor status were significantly associated with a low extent of apoptosis (P = 0.010 and P = 0.042, respectively). Their changes were parallel to the changes in apoptosis during tumor progression, although the associations did not reach statistical significance. The results show that increased apoptosis is associated with a worse prognosis in breast carcinoma. A significant increase in apoptosis in recurrent breast carcinoma lesions predicts a worse clinical outcome. (+info)
Progestins inhibit the growth of MDA-MB-231 cells transfected with progesterone receptor complementary DNA.
(10/3862)
Because progesterone exerts its effects mainly via estrogen-dependent progesterone receptor (PgR), the expression of progesterone's effects may be overshadowed by the priming effect of estrogen. PgR expression vectors were transfected into estrogen receptor (ER)-alpha and PgR-negative breast cancer cells MDA-MB-231; thus the functions of progesterone could be studied independent of estrogens and ERs. Eight stable transfectant clones expressing both PgR isoform A and B were studied for their growth response to progesterone and its analogues. Although progesterone had no effect on growth in the control transfectant, the hormone markedly inhibited DNA synthesis and cell growth in all of the PgR-transfectants dose-dependently from 10(-12)-10(-6) M. This growth inhibition was associated with an arrest of cells in the G0/G1 phase of the cell cycle. Progestins medroxyprogesterone acetate, Org2058, and R5020 also strongly inhibited DNA synthesis, and their doses required for maximal inhibition of 60-70% were 10(-17) M, 10(-13) M, and 10(-7) M, respectively. Antiprogestin ZK98299 alone had no effect, but the compound was capable of counteracting the inhibitory effect of progesterone. In contrast, RU486 inhibited DNA synthesis, and it showed no further effects when it was used concurrently with progesterone. These results indicate that progestins are per se antiproliferative via a PgR-mediated mechanism in breast cancer cells. More importantly, we have shown that progestins may exert effective inhibitory control over the cell growth if the PgR expression is reactivated in ER- and PgR-negative breast cancer cells. (+info)
Proteasome-dependent degradation of the human estrogen receptor.
(11/3862)
In eukaryotic cells, the ubiquitin-proteasome pathway is the major mechanism for the targeted degradation of proteins with short half-lives. The covalent attachment of ubiquitin to lysine residues of targeted proteins is a signal for the recognition and rapid degradation by the proteasome, a large multi-subunit protease. In this report, we demonstrate that the human estrogen receptor (ER) protein is rapidly degraded in mammalian cells in an estradiol-dependent manner. The treatment of mammalian cells with the proteasome inhibitor MG132 inhibits activity of the proteasome and blocks ER degradation, suggesting that ER protein is turned over through the ubiquitin-proteasome pathway. In addition, we show that in vitro ER degradation depends on ubiquitin-activating E1 enzyme (UBA) and ubiquitin-conjugating E2 enzymes (UBCs), and the proteasome inhibitors MG132 and lactacystin block ER protein degradation in vitro. Furthermore, the UBA/UBCs and proteasome inhibitors promote the accumulation of higher molecular weight forms of ER. The UBA and UBCs, which promote ER degradation in vitro, have no significant effect on human progesterone receptor and human thyroid hormone receptor beta proteins. (+info)
Isolation and characterization of a new human breast cancer cell line, KPL-4, expressing the Erb B family receptors and interleukin-6.
(12/3862)
A new human breast cancer cell line, KPL-4, was recently isolated from the malignant pleural effusion of a breast cancer patient with an inflammatory skin metastasis. This cell line can be cultured under serum-free conditions and is tumorigenic in female athymic nude mice. Flow cytometric analysis revealed the expression of Erb B-1, -2 and -3. Dot blot hybridization showed a 15-fold amplification of the erb B-2. Reverse transcription-polymerase chain reaction analysis showed a detectable level of mRNA expression of all the Erb B family receptors. In addition, all the receptors were autophosphorylated under a serum-supplemented condition. Unexpectedly, transplanted KPL-4 tumours induced cachexia of recipient mice. A high concentration of interleukin-6 (IL-6) was detected in both the culture medium and the serum of mice. The weight of tumours significantly correlated with the serum IL-6 level. The antiproliferative effect of a humanized anti-Erb B-2 monoclonal antibody, rhuMAbHER2, was investigated. This antibody significantly inhibited the growth of KPL-4 cells in vitro but modestly in vivo. Loss of mouse body weight was partly reversed by rhuMAbHER2. These findings suggest that KPL-4 cells may be useful in the development of new strategies against breast cancer overexpressing the Erb B family receptors and against IL-6-induced cachexia. (+info)
Expression of prostate-specific antigen (PSA) correlates with poor response to tamoxifen therapy in recurrent breast cancer.
(13/3862)
Prostate-specific antigen (PSA) is a serine protease which may play a role in a variety of cancer types, including breast cancer. In the present study, we evaluated whether the level of PSA in breast tumour cytosol could be associated with prognosis in primary breast cancer, or with response to tamoxifen therapy in recurrent disease. PSA levels were determined by enzyme-linked immunosorbent assay (ELISA) in breast tumour cytosols, and were correlated with prognosis in 1516 patients with primary breast cancer and with response to first-line tamoxifen therapy in 434 patients with recurrent disease. Relating the levels of PSA with classical prognostic factors, low levels were more often found in larger tumours, tumours of older and post-menopausal patients, and in steroid hormone receptor-negative tumours. There was no significant association between the levels of PSA with grade of differentiation or the number of involved lymph nodes. In patients with primary breast cancer, PSA was not significantly related to the rate of relapse, and a positive association of PSA with an improved survival could be attributed to its relationship to age. In patients with recurrent breast cancer, a high level of PSA was significantly related to a poor response to tamoxifen therapy, and a short progression-free and overall survival after start of treatment for recurrent disease. In Cox multivariate analyses for response to therapy and for (progression-free) survival, corrected for age/menopausal status, disease-free interval, site of relapse and steroid hormone receptor status, PSA was an independent variable of poor prognosis. It is concluded that the level of PSA in cytosols of primary breast tumours might be a marker to select breast cancer patients who may benefit from systemic tamoxifen therapy. (+info)
Time at surgery during menstrual cycle and menopause affects pS2 but not cathepsin D levels in breast cancer.
(14/3862)
Many studies have addressed the clinical value of pS2 as a marker of hormone responsiveness and of cathepsin D (Cath D) as a prognostic factor in breast cancer. Because pS2 and Cath D are both oestrogen induced in human breast cancer cell lines, we studied the influence of the menstrual cycle phase and menopausal status at the time of surgery on the levels of these proteins in breast cancer. A population of 1750 patients with breast cancer, including 339 women in menstrual cycle, was analysed. Tumoral Cath D and pS2 were measured by radioimmunoassay. Serum oestradiol (E2), progesterone (Pg), follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels at the day of surgery were used to define the hormonal phase in premenopausal women. There was a trend towards a higher mean pS2 level in the follicular phase compared with the luteal phase (17 ng mg(-1) and 11 ng mg(-1) respectively, P = 0.09). Mean pS2 was lower in menopausal patients than in women with cycle (8 ng mg(-1) and 14 ng mg(-1) respectively, P = 0.0001). No differences in mean Cath D level were observed between the different phases of the menstrual cycle, or between pre- and post-menopausal women. In the overall population, pS2 was slightly positively associated with E2 and Pg levels and negatively associated with FSH and LH, probably reflecting the link between pS2 and menopausal status. In premenopausal women, no association was found between pS2 and E2, Pg, FSH or LH levels. There were no correlations between Cath D level and circulating hormone levels in the overall population. However, in the subgroup of premenopausal women with ER-positive (ER+) tumours, E2 was slightly associated with both pS2 and Cath D, consistent with oestrogen induction of these proteins in ER+ breast cancer cell lines. There are changes in pS2 level in breast cancer throughout the menstrual cycle and menopause. This suggests that the choice of the pS2 cut-off level should take the hormonal status at the time of surgery into account. In contrast, the level of Cath D is unrelated to the menstrual cycle and menopausal status. (+info)
Androgen receptor expression in male breast carcinoma: lack of clinicopathological association.
(15/3862)
Androgen receptor (AR) expression was retrospectively analysed in 47 primary male breast carcinomas (MBCs) using a monoclonal antibody on formalin-fixed, paraffin-embedded tissues. AR immunopositivity was detected in 16 out of 47 (34%) cases. No association was found with patient age, tumour stage, progesterone receptor (PGR) or p53 protein expression. Well-differentiated MBCs tended to be AR positive more often than poorly differentiated ones (P = 0.08). A negative association was found between ARs and cell proliferative activity: MIB-1 scores were higher (25.4%) in AR-negative than in AR-positive cases (21.11%; P = 0.04). A strong positive association (P = 0.0001) was found between ARs and oestrogen receptors (ERs). In univariate analysis, ARs (as well as ERs and PGRs) were not correlated with overall survival; tumour histological grade (P = 0.02), size (P = 0.01), p53 expression (P = 0.0008) and MIB-1 scores (P = 0.0003) had strong prognostic value. In multivariate survival analysis, only p53 expression (P = 0.002) and histological grade (P = 0.02) retained independent prognostic significance. In conclusion, the lack of association between AR and most clinicopathological features and survival, together with the absence of prognostic value for ER/PGR status, suggest that MBCs are biologically different from female breast carcinomas and make it questionable to use antihormonal therapy for patients with MBC. (+info)
The relationship between a polymorphism in CYP17 with plasma hormone levels and breast cancer.
(16/3862)
The A2 allele of CYP17 has been associated with polycystic ovarian syndrome, elevated levels of certain steroid hormones in premenopausal women, and increased breast cancer risk. We prospectively assessed the association between the A2 allele of CYP17 and breast cancer risk in a case-control study nested within the Nurses' Health Study cohort. We also evaluated associations between this CYP17 genotype and plasma steroid hormone levels among postmenopausal controls not using hormone replacement to assess the biological significance of this genetic variant. Women with the A2 allele were not at an increased risk of incident breast cancer [OR (odds ratio), 0.85; 95% CI (confidence interval), 0.65-1.12] or advanced breast cancer (OR, 0.84; 95% CI, 0.54-1.32). We did observe evidence that the inverse association of late age at menarche with breast cancer may be modified by the CYP17 A2 allele. The protective effect of later age at menarche was only observed among women without the A2 allele (A1/A1 genotype: for age at menarche > or =13 versus <13; OR, 0.57; 95% CI, 0.36-0.90; A1/A2 and A2/A2 genotypes: OR, 1.05; 95% CI, 0.76-1.45; P for interaction = 0.07). Among controls, we found women with the A2/A2 genotype to have elevated levels of estrone (+14.3%, P = 0.01), estradiol (+13.8%, P = 0.08), testosterone (+8.6%, P = 0.34), androstenedione (+17.1%, P = 0.06), dehydroepiandrosterone (+14.4%, P = 0.02), and dehydroepiandrosterone sulfate (+7.2%, P = 0.26) compared with women with the A1/A1 genotype. These data suggest that the A2 allele of CYP17 modifies endogenous hormone levels, but is not a strong independent risk factor for breast cancer. (+info)