Apoptosis, proliferation, and sex hormone receptors in superficial parts of human endometrium at the end of the secretory phase.

Apoptosis with one regulator, Bcl-2, and proliferation with the marker Ki-67 were studied in 75 endometrial biopsies representing superficial parts of endometrium from 35 regularly menstruating women premenstrually and menstrually. Hormonal withdrawal was studied in serum samples and potentiated in epithelium by the decreasing 17beta-estradiol and progesterone receptor scores 4 days premenstrually. The apoptotic index increased 2 days before the onset of menstruation and peaked on the second menstrual day. The high apoptotic index together with low proliferation in endometrial epithelium at the end of the menstrual cycle are similar to the involution process seen in other hormone-dependent organs. In stroma, the apoptotic index increased later, at the onset of menstruation, and the increase was lower than that in epithelium. The Ki-67 index increased during the last 3 days of the secretory phase, parallel with an increasing progesterone receptor score and decreasing Bcl-2 staining, and peaked at the onset of menstruation. The findings in stroma concur with high proliferation at the end of the menstrual cycle and high cell turnover during menstruation, suggesting the participation of stroma in the renewal process of endometrium.

Early castration-induced upregulation of transforming growth factor beta1 and its receptors is associated with tumor cell apoptosis and a major decline in serum prostate-specific antigen in prostate cancer patients.

BACKGROUND: The mechanism behind castration-induced apoptosis in prostate cells is unknown, but data from other species suggest that transforming growth factor beta1 (TGF-beta1) may be involved. METHODS: By using quantitative RT-PCR and immunohistochemistry, expression of TGF-beta1 and its receptors type I and II (RI and RII) was studied in normal and tumor areas of core biopsies taken before and 2-11 days after castration therapy. The TGF-beta responses were related to changes in apoptotic index and to changes in serum prostate-specific antigen (PSA). RESULTS: In normal prostate tissue, apoptosis was generally increased by castration, and apoptosis was accompanied by an increase in TGF-beta1 and RII mRNA levels (P < 0.05). In tumors, apoptosis was seen only in 44% of the cases and in these, but not in the others, TGF-beta1, RI, and RII mRNA levels were increased (P < 0.05). In the patients showing a prognostically favorable PSA response (nadir PSA <5 ng/ml), but not in the others, RI and RII mRNA levels were significantly upregulated (P < 0.05). CONCLUSIONS: Short-term upregulation of TGF-beta1 and its receptors is associated with apoptosis in human prostate and prostate cancer, and possibly with a favorable clinical outcome after castration therapy.

Apoptosis and other mechanisms in androgen ablation treatment and androgen independent progression of prostate cancer: a review.

Patients with advanced prostate cancer commonly present with disseminated disease. For these patients, androgen ablation is a first-line treatment. This mode of therapy usually has an initially palliative effect on tumor-related symptoms and slows growth, although virtually all tumors eventually relapse to an androgen-independent, more aggressively growing phenotype. However, surprisingly little is known about the actions mediating the initial palliative effect as well as the initiation of androgen-independent tumor growth. In this review, some current concepts on mechanisms of androgen ablation treatment and androgen-independent progression of prostate cancer is highlighted. Special attention is given to the involvement of apoptosis in these processes.

Short-term cellular effects induced by castration therapy in relation to clinical outcome in prostate cancer.

To explore the relationship between short-term effects of castration therapy and clinical response, biopsies obtained before and a week after castration therapy from 15 responding and 13 non-responding patients with prostate cancer were investigated. The biopsies were assessed for regressive morphology, apoptotic index by morphological criteria, nuclear area, and immunoreactivity (IR) for Ki-67, p53, bcl-2, bax and Fas. The index was defined as the percentage of immunoreactive cells in a tumour. Regressive morphology was observed in 14 out of 15 responding tumours after therapy, compared with 4 out of 13 non-responders (P < 0.001). Median tumour epithelial cell nuclear area and Ki-67 index decreased equally in both groups. The median apoptotic index increased from 2.6 to 3.5 after castration among responders (P < 0.05), whereas it remained at 2.8 among non-responders. p53 IR was present in three tumours before castration; after therapy p53 reactivity was seen in three additional tumours belonging to the responding group. Median bcl-2 index increased in responders from 1.5 to 10.0 (P < 0.05), and in non-responders from 0.08 to 2.7 (P < 0.05). Bax IR and Fas IR were present in all tumours before therapy and unchanged after therapy. Thus, regressive morphology and an increase in apoptotic index were related to a favourable clinical response. These data suggest that it might be possible to predict the effect of castration therapy by examining tumour biopsies shortly after treatment.

bcl-2 expression confers androgen independence in androgen sensitive prostatic carcinoma.

Expression of the bcl-2 proto-oncogene is associated with the progression of prostate cancer to androgen-independence. Dunning R3327G (DG) cells were engineered to express high levels of bcl-2 protein. The parental DG (DG-P) cell line and bcl-2 transfectant (DG-B) clones were grown as subcutaneous tumor explants in male athymic nude mice. The rate of tumor growth after castration was significantly lower in DG-P tumors but was unaffected in DG-B tumors. The proliferative indices (PI) in DG-P and DG-B tumors were similar, however, apoptotic indices (ApI) were significantly lower in DG-B tumors before castration. Following castration the PI and ApI decreased significantly in DG-P but not DG-B tumors. Bax upregulation was not observed in the DG-P or DG-B tumors, but did occur in the ventral prostate, after castration. These findings support a role for bcl-2 expression in conferring androgen-independent growth during prostate cancer progression.

Castration plus oestrogen treatment induces but castration alone suppresses epithelial cell apoptosis in an androgen-sensitive rat prostatic adenocarcinoma.

The positive effect of castration in prostatic cancer patients is considered to be related to the induction of apoptosis in androgen-dependent tumour cells. However, castration apparently does not induce apoptosis in the highly differentiated, androgen-sensitive Dunning R3327PAP rat prostatic adenocarcinoma. To elucidate potential mechanisms of apoptotic induction in this tumour model, rats with subcutaneously implanted tumours were treated with vehicle (I), castration+vehicle (C) or castration + 50 micrograms of oestradiol benzoate per day s.c. (C + E2). The effects on tumours were examined by morphometry, in situ end labelling (ISEL) of apoptotic cells and immunohistochemically with monoclonal antibodies to proliferating cell nuclear antigen (PCNA) at different time points up to 168 h after castration. Castration inhibited tumour growth and decreased the epithelial cell apoptotic rate (from 12 h) and epithelial cell proliferation rate (from 72 h) compared with that in the I group. Tumour volume, volume densities of epithelium and stroma and stroma cell proliferation rate remained constant in the C group during the study period. C + E2 treatment resulted in increases in cell proliferation in the stroma (from 12 h) and in the volume density of stroma (from 24 h) compared with that in the C and I groups. The number of apoptotic epithelial cells was increased (from 24 h), and this was followed by decreases in the volume density of epithelium (from 24 h), the epithelial cell proliferation rate (from 72 h) and the total tumour volume (from 72 h). We conclude that in the Dunning R3327PAP tumour model C + E2 treatment is more effective than castration alone. C+E2 treatment, in contrast to C, is able to induce tumour cell death and to decrease total tumour volume. The mechanism behind this effect is unknown, but it could be related to stimulatory effects of E2 in the tumour stroma.

Castration therapy rapidly induces apoptosis in a minority and decreases cell proliferation in a majority of human prostatic tumors.

Major differences in the long-term clinical response to castration therapy of prostatic carcinoma suggests intertumoral differences in cellular response and defines a need for identification of patients with an eventually positive outcome as well as those in need of additional treatment. Using morphometry, monoclonal antibodies against Bcl-2, c-myc, Ki-67, and p53 proteins, and an in situ method to visualize apoptotic cells, we examined the short-term response of prostatic tumors to castration in core biopsies from 18 prostatic cancer patients taken the day before and 7 days after castration. At the histological level, 3 tumors seemed practically unaffected by castration. In 15 tumors, castration induced vacuolization of tumor cell cytoplasm and decreases in nuclear area and Ki-67 index. In these 15 tumors, apoptotic index was significantly increased in 6, principally unaffected in 6, and decreased in 3. The 6 tumors responding with an increase in apoptotic index were WHO grade 1 or 2 and negative for p53, c-myc, and Bcl-2 or contained only few Bcl-2- or c-myc-positive tumor cells before therapy. The 12 tumors in which apoptotic index was unaffected or decreased were WHO grade 2 or 3 and immunopositive for one or more of p53, Bcl-2, and c-myc proteins before therapy. The Bcl-2 index was significantly increased in 10 patients. Prostatic tumors may respond in a variety of possibly predictable ways to castration therapy including a decrease in apoptotic index. The magnitude of these responses are not correlated in individual tumors, suggesting that the common classification of prostatic tumors as either androgen dependent (dying after castration) or independent (not responding at all to castration) may be an oversimplification.

Castration induces apoptosis in the ventral prostate but not in an androgen-sensitive prostatic adenocarcinoma in the rat.

Apoptosis in the androgen-sensitive Dunning R3327 PAP prostatic adenocarcinoma was studied during the post castration period of 14 days and compared with the ventral prostate. The mRNA expression of testosterone repressed prostatic message-2 and tissue-type plasminogen activator in the Dunning tumor and in the ventral prostate was analyzed by Northern blot experiments and immunohistochemical procedures. The degree of endonuclease-degraded genomic DNA was examined by gel electrophoresis. Apoptotic tumor epithelial cells were identified with in situ end labeling. Epithelial cells incorporating bromodeoxyuridine (BrdUrd) after castration in the ventral prostate and the Dunning tumors were localized with immunostaining. Androgen ablation resulted in an induction of testosterone repressed prostatic message-2 and tissue-type plasminogen activator transcripts in the normal prostate with a peak at approximately 2 to 5 days post castration. These transcript levels in the Dunning prostatic tumors did not show any induction during the same period. Immunohistochemical staining for sulfated glycoprotein-2 and tissue-type plasminogen activator confirmed this difference between the tumor tissue and the ventral prostate at the transcriptional level. The determination of DNA integrity showed similar results in that the degree of DNA fragmentation in the tumor was much lower than the initial and marked degradation of DNA in the ventral prostate. The number of in situ end-labeled epithelial tumor cells were not increased by castration. BrdUrd immunodetection showed that castration induced an initial increase in the number of BrdUrd-positive epithelial cells in the ventral prostate. In the tumors, castration resulted in a decrease in BrdUrd-positive epithelial cells. It was concluded that in the androgen-sensitive prostatic Dunning R3327 PAP adenocarcinoma, the biochemical cascade leading to apoptosis is not activated by androgen withdrawal, as in the ventral prostate.

Castration rapidly results in a major reduction in epithelial cell numbers in the rat prostate, but not in the highly differentiated Dunning R3327 prostatic adenocarcinoma.

Rats with implanted highly differentiated Dunning R3327PAP prostatic tumors were castrated, and at 3, 7, and 14 days thereafter, the effects on tumor volume, epithelial cell numbers, and sizes were quantified using morphometrical methods. The castration response on these parameters was also examined in the normal prostate of the same rats. Castration resulted in a rapid decrease in organ volume, epithelial cell number, and size in the normal prostate, and morphological signs of epithelial cell death (apoptosis) were observed. Tumor growth and mitotic index were reduced, but there were no signs of increased apoptosis, and cell numbers remained fairly constant in the Dunning tumors during the study period. It is concluded that the castration-induced inhibition of tumor growth is caused by factors other than tumor cell death.