The extent of proliferative and apoptotic activity in intraductal and invasive ductal breast carcinomas detected by Ki-67 labeling and terminal deoxynucleotidyl transferase-mediated digoxigenin-11-dUTP nick end labeling

Oxidant stress evoked damage in rat hepatocyte leading to triggered nitric oxide synthase (NOS) levels on long term consumption of aspartame

This study investigates how long-term (40 mg/kg b.wt) consumption of aspartame can alter the antioxidant status, stress pathway genes, and apoptotic changes in the liver of Wistar albino rats. Numerous controversial reports are available on the use of aspartame as it releases methanol as one of its metabolites during metabolism. To mimic the human methanol metabolism the methotrexate treated rats were included to study the aspartame effects. The aspartame treated methotrexate (MTX animals showed a marked significant increase in the superoxide dismutase (SOD), catalase (CAT), lipid peroxidation (LPO), and Glutathione peroxidase (GPx) activity in the liver from control and MTX control animals, and showed a significant decrease in reduced glutathione (GSH) and protein thiol in aspartame treated animals. The aspartame treated MTX animals showed a marked significant decrease in the body weight, brain, and liver weight. The aspartame treated MTX animals showed a marked increase in the inducible nitric oxide (iNOS), neuronal nitric oxide (nNOS), c-fos, Heat shock protein (Hsp) 70 Tumour necrosis Factor (TNF)α, caspase 8, c-jun N terminal kinases (JNK) 3 and Nuclear factor kappa B (NFkB) gene expression in the liver from control and MTX control animals. The aspartame treated MTX animals showed a marked increase in the c-fos, Hsp 70, iNOS Caspase 8, and JNK 3 protein expression in the liver from control and MTX control animals indicating the enhancement of stress and apoptosis. The aspartame treated MTX animals showed a streak of marked DNA fragmentation in the liver. On immunohistochemical analysis aspartame treated animals showed brown colored positive hepatocytes indicating the stress specific and apoptotic protein expression. Since aspartame consumption is on the rise among people, it is essential to create awareness regarding the usage of this artificial sweetener.

Vasohibin-1 as a potential predictor of aggressive behavior of ductal carcinoma in situ of the breast

Vasohibin-1 is a recently identified negative feedback regulator of angiogenesis induced by VEGF-A and bFGF. In this study, we first evaluated mRNA expression of vasohibin-1 and CD31 in 39 Japanese female breast carcinoma specimens including 22 invasive ductal carcinoma (IDC) and 17 ductal carcinoma in situ (DCIS) using a real-time quantitative RT-PCR (QRT-PCR) with LightCycler system. In addition, we also immunolocalized vasohibin-1 and CD31 and compared their immunoreactivity to nuclear grades and histological grades of 100 carcinoma cases (50 IDC and 50 DCIS). There were no statistically significant differences of CD31 mRNA expression and the number of CD31 positive vessels between DCIS and IDC (P = 0.250 and P = 0.191, respectively), whereas there was a statistically significant difference in vasohibin-1 mRNA expression and the number of vasohibin-1 positive vessels in DCIS and IDC (P = 0.022 and P < or = 0.001, respectively). There was a significant positive correlation between vasohibin-1 mRNA level and Ki-67 labeling index in DCIS (r(2) = 0.293, P < or = 0.001). In addition, vasohibin-1 mRNA expression was correlated with high nuclear and histological grades in DCIS cases and a significant positive correlation was detected between the number of vasohibin-1 positive vessels and Ki-67 labeling index or nuclear grade or Van Nuys classification of carcinoma cells (P < or = 0.001, respectively). These results all indicate the possible correlation between aggressive biological features in DCIS including increased tumor cell proliferation and the status of neovascularization determined by vasohibin-1 immunoreactivity.

Pattern of Proliferative Index (Ki-67) After Anti-Androgen Manipulation Reflects the Ability of Irradiation to Control Prostate Cancer

Anti-androgen (AA) therapy will cause hormone-sensitive prostate cancer cells to undergo apoptosis and/or enter the resting phase of the cell cycle. Although the decrease of tumor burden would be an advantage for tumor control when irradiation is subsequently added, the cells in resting phase would seemingly be less vulnerable to the usual type of radiation-induced cell killing via DNA strand breakage. In this study of patients with prostate cancer, we examined the proliferative index via Ki-67 staining of biopsy material before, during, and after withdrawal of leuprolide. We studied 15 previously untreated patients with locally advanced prostate cancer. Prostate biopsies were taken at three times: 1) initial diagnosis; 2) after 3 consecutive months of intramuscular 7.5 mg depot; and c) 6 weeks after the last dose. External beam radiation (EBRT) then delivered 66 Gy in 33 sessions to local fields. We used the ASTRO definition of prostate-specific antigen (PSA) failure. We measured serum luteinizing hormone and total testosterone coinciding with each biopsy date. Immunohistochemical staining was performed using Ki-67 antibody clone MIB-1. The follow-up ranged from 36 to 73 months (median 52 months). We discerned two perturbation patterns of Ki-67 with hormonal manipulation. Pattern 1 demonstrated a drop of Ki-67 labeling after leuprolide was in effect and then after leuprolide withdrawal, the Ki-67 rebounded to less than 120% of baseline. Pattern 2 also showed an initial drop with leuprolide but rebounded to more than 120%. Among eight patients demonstrating pattern 1, only one patient had a PSA failure. In contrast among patients with pattern 2, six of seven failed biochemically (Fisher's exact, p = 0.018). All patients had a LH less than 1.0 during leuprolide effect that rose with its withdrawal. There was no correlation of PSA failure with whether total testosterone did or did not rise to more than 100 ng/dl by the time of the withdrawal phase biopsy. Neither the percent of PSA decline during leuprolide nor the minor PSA rebound 6 to 8 weeks after leuprolide withdrawal correlated with the Ki-67 pattern. The pattern of perturbation of immunohistochemical staining for Ki-67 predicts biochemical failure after moderate-dose EBRT in patients with prostate cancer. Several recent analyses of combined EBRT and AA suggest that some patients may benefit from more prolonged use of AA. Because AA can have substantial side effects and is expensive, a method to select patients likely to benefit from long-term AA would be useful. After neoadjuvant AA manipulation, the Ki-67 perturbation pattern, but not the early PSA changes, may help select patients for long-term AA. The Ki-67 pattern might also be used to select patients needing escalated radiation dosage. Further validation of these concepts beyond this pilot study is suggested.

Differential expression of Akt/protein kinase B, Bcl-2 and Bax proteins in human leiomyoma and myometrium

The expression and activation of serine/threonine protein kinase, Akt, in leiomyoma and in adjacent myometrium of human uteri was studied parallel with the changes of Bcl-2, Bax proteins, estrogen and progesterone receptors during menstrual cycle and early stage of the menopause. Abundant expression of Akt protein was detected in the studied tissues during menstrual cycle, the rate of increase was higher in leiomyoma than in corresponding myometrium. The expression of estrogen receptor alpha, progesterone receptor and of Bcl-2 protein changed parallel with that of Akt protein. The level of phosphorylated Akt (pAkt(473)) was seen only in leiomyoma samples from the growing period of tumors. At early stage of menopause levels of all studied proteins were lower than that in the menstrual cycle with the exception of Bax protein expression, which was high in leiomyoma. Our data suggest the involvement of phosphatidylinositol 3-kinase/Akt signaling in the pathomechanism of leiomyoma.

Endometriosis-associated ovarian carcinoma: differential expression of vascular endothelial growth factor and estrogen/progesterone receptors

BACKGROUND

Multiple epidemiologic and histologic studies have suggested that ovarian endometriosis can give rise to malignant ovarian tumors, primarily those of epithelial origin. The progression of endometriosis to endometriosis-associated ovarian carcinoma (EAOC) has not been investigated thoroughly and is poorly understood at best. Using immunohistochemical methods, we compared the differential expression patterns of various cytokines and growth factors in atypical endometriosis (AE) and EAOC.

METHODS

Using the Johns Hopkins Pathology Data Bank, tissue blocks from patients diagnosed with EAOC or AE were identified. Tissue blocks were stained for 4 markers: vascular endothelial growth factor (VEGF), Ki-67, estrogen receptor (ER), and progesterone receptor (PR).

RESULTS

Seventeen cases of EAOC and 8 cases of AE were identified. Staining for VEGF was documented in 16 of 17 (94%) EAOC tissue blocks and in only 1 of 8 (12.5%) AE tissue blocks (P < 0.0001). Only 4 of the 17 (23%) EAOC tissue blocks exhibited positive staining for ER, compared with 8 of 8 (100%) AE tissue blocks (P = 0.0005). Positive staining for PR was noted in only 6 of 17 (35%) EAOC samples but was present in 8 of 8 (100%) AE samples (P = 0.003). Seventy percent of EAOC samples exhibited positive staining for Ki-67, compared with 37.5% of AE samples (P = 0.19).

CONCLUSIONS

EAOC appears to be associated with overexpression of VEGF and reduced expression of both ER and PR. Variations in VEGF expression may be associated with the malignant transformation of endometriosis and may present both diagnostic and therapeutic options for the treatment of ovarian malignancies.

Lack of apoptosis in PanIN-1 and PanIN-2 lesions associated with pancreatic ductal adenocarcinoma is not dependent on K-ras status

INTRODUCTION

K-ras mutations are present in most ductal adenocarcinomas (DACs) of the pancreas and may also be found in ductal precursor lesions and even in normal ductal epithelium. The question is addressed whether mutated K-ras interferes with the regulation of apoptosis or proliferation.

METHODOLOGY

In 50 Whipple resection specimens, tissue adjacent to DACs was histologically screened for ductal lesions that were classified as pancreatic intraepithelial neoplasia (PanIN) according to WHO criteria. PanIN lesions were microdissected and analyzed for K-ras mutations by means of a nested PCR. Apoptosis was identified by the TUNEL method. Proliferation and the expression of p53 and Bcl-2 were immunohistochemically determined.

RESULTS

On average, 30% of PanIN-1A and B lesions showed mutated K-ras. In PanIN-2 and PanIN-3 lesions, the rate of mutated K-ras increased to 45% and 56%, respectively. Apoptosis was present only in 2 of 26 PanIN-3 lesions. There was a gradual increase in proliferative activity from PanIN-1 to PanIN-3. p53 expression was found in 11% of PanIN-2 and 44% of PanIN-3 lesions. Bcl-2 expression was lacking in PanIN lesions of all grades. In invasive DACs, the apoptotic rate correlated with the degree of tumor differentiation and proliferation, with grade 3 carcinomas showing the highest apoptotic rate.

CONCLUSION

In view of the discrepancy between the considerable rate of K-ras mutations in PanIN-1 and PanIN-2 lesions and the lack of apoptosis and Bcl-2 expression, coupled with very low p53 immunoreactivity, it is unlikely that mutated K-ras affects the apoptotic activity in low grade PanINs. Instead, K-ras mutations may have an effect on proliferation in PanIN-1 and PanIN-2.

Prognostic significance of glutathione S-transferase-pi in invasive breast cancer

Glutathione S-transferase pi (GST-pi), a Phase II detoxification enzyme, has recently been implicated in protection against apoptosis. Expression of GST-pi and Bcl-2 protein, an established apoptosis marker, was analyzed by immunohistochemistry in 116 cases of infiltrative ductal breast carcinomas in Singapore women. The markers were correlated with apoptosis detected by the TUNEL method and clinico-pathological parameters. There were 67 (58%) GST-pi-positive breast tumors and 43 (37%) Bcl-2-positive tumors. In a large proportion of GST-pi-positive/Bcl-2-positive tumors, there was a distinct accumulation of the GST-pi enzyme within the nucleus of cancer cells when examined by double immunofluorescence labeling under confocal microscopy. GST-pi immunoreactivity was not significantly correlated with any of the traditional histologic factors known to influence prognosis, whereas Bcl-2 overexpression was associated with reduced size of primary tumor (P =.021) and positive estrogen receptor status (P =.001). Univariate analysis revealed that GST-pi-positive, Bcl-2-positive, and lower histological grade tumors had decreased levels of apoptosis (P =.024, P =.011, and P =.029, respectively). However, multivariate analysis showed that histological grade and Bcl-2, but not GST-pi, immunoreactivity were correlated with apoptotic status. The Kaplan-Meier disease-free survival curves showed a significant difference between GST-pi-positive and GST-pi-negative breast cancer cases (P =.002). Disease-free survival in patients with GST-pi-positive tumors was also worse than that in patients with GST-pi-negative tumors in the group who had adjuvant chemotherapy (P =.04). In patients who were lymph node positive, GST-pi immunopositivity was found to influence disease-free survival. Recurrence of tumors was also significantly affected by GST-pi immunoreactivity (relative risk of 8.1). The findings indicate that GST-pi-positive tumors are more aggressive and have a poorer prognosis than do corresponding GST-pi-negative breast cancers.

Flow cytometric detection of spontaneous apoptosis in human breast cancer using the TUNEL-technique

Microscopic detection of structural alterations is the most reliable method to identify apoptotic cells, which however, does not allow any correlation with cell cycle phases. Discrimination of individual cells within solid human tumors undergoing apoptotic death is possible by flow cytometry where apoptotic cells appear in a hypodiploid sub G0/1-peak as a consequence of partial DNA loss. To refer induction of apoptosis to cell cycle phases we adopted the terminal deoxynucleotidyl transferase nick-end-labelling (TUNEL) technique to flow cytometry which enables the detection of cellular DNA content and DNA fragmentation by multiparametric analysis. One thousand seven hundred human breast carcinomas were screened. In 40 cases (2.3%) of 1700 carcinomas we detected a hypodiploid sub -G0/1 apoptotic peak. The spontaneous apoptotic fractions within individual tumors ranged between 1.5 and 25%. A correlation (r(2)=0.78) was found between apoptotic cells in sub-G0/1-peak measured by DNA-cytometry and TUNEL positive cells measured by multiparametric cytometry, because TUNEL reaction signed also cells with strand breaks. High proliferation indices correspond well (r(2)=0.807) with the increased amount of TUNEL positive cells. Multiparametric flow cytometry for the combined determination of DNA-content and DNA-fragmentation by TUNEL offers not only the advantage of a higher apoptosis sensitivity but also enables the quantification of DNA fragmentation related to any cell cycle phase.

MIB-1 Assessments in breast cancers

The variability of MIB-1 measurements in breast cancer was assessed in histological sections from core and excision biopsies taken simultaneously in 13 cases and sequentially (with an intervening period of 2-3 weeks) in 17 cases. Results showed no significant differences in values between cores and sections, whether taken simultaneously or sequentially. Individual pairs of cores and sections occasionally demonstrated substantial differences. The mean ratio of MIB-1 scores between cores and sections was 0.97 [95% confidence interval (CI)=0.68-1.38]. However 95% confidence intervals for ratios within individuals were 0.14-6.68. Although the two samples can be equivalent on an average over numerous patients, they cannot be taken as equivalent within individuals. Severe heterogeneity complicates the assessment of MIB-1 in individual breast cancers and limits utility in monitoring changes in proliferation with treatment.

Expression of Bcl-2, Bcl-x, Mcl-1, Bax and Bak in human uterine leiomyomas and myometrium during the menstrual cycle and after menopause

To investigate the expression of Bcl-2, Bcl-x, Mcl-1, Bax and Bak proteins in human uterine leiomyomas and homologous myometrium during the menstrual cycle and after menopause. The expression of Bcl-2, Bcl-x, Mcl-1, Bax and Bak in leiomyomas (n=24) and myometrial samples (n=22) from women with leiomyomas was measured by immunohistochemistry and Western blot. Measured by immunohistochemistry, a significant difference between leiomyomas and myometrium was observed only for the Bax protein, in tissues obtained from women in the secretory phase of the menstrual cycle. The Bcl-2 staining was more abundant in leiomyomas than in myometrium only in tissues obtained in the proliferative phase of the cycle. Bcl-2 was more abundant in leiomyomas from women of fertile age than in leiomyomas from menopausal women. No significant differences were observed for the Bcl-x or Bak proteins, whereas the Mcl-1 protein was significantly less abundant in secretory phase leiomyomas than in leiomyomas from menopausal women. Western blot analysis based on pools of tissue extracts from the different groups essentially confirmed the data obtained by immunohistochemistry. Bcl-2 family proteins are expressed in leiomyomas and myometrium in different phases related to and influenced by gonadal steroids. These proteins are suggested to interact with each other in the regulation of programmed cell death, apoptosis, but their specific role in growth control of uterine leiomyomas remains to be investigated.

Pleomorphic lobular carcinoma of the breast: its cell kinetics, expression of oncogenes and tumour suppressor genes compared with invasive ductal carcinomas and classical infiltrating lobular carcinomas

AIMS

The study addresses whether pleomorphic lobular breast carcinomas represent a distinct entity with respect to proliferation and apoptosis as well the expression of the p53, bcl-2 and Her2 protein.

METHODS AND RESULTS

The study included 30 cases of pleomorphic lobular carcinoma (PLC; G2 n=15, G3 n=15). Poorly differentiated invasive ductal carcinomas (IDC; n=15) and well-differentiated infiltrating lobular carcinomas (ILC; n=15) were used as controls. Lymph node metastases were present equally in all groups. MIB-1 labelling was counted as: PLC (G2) 8.36%; PLC (G3) 11.3%; IDC 44.26%; ILC 2.19% (P=0.0001, P=0.004, P=0.001). Apoptotic index was: PLC (G2) 0.82%; PLC (G3) 1.2%; IDC 2.09%; ILC 0.6% (P=0.009, P=0.001). Over-expression of Her2 protein was detected in 53% of PLC (G3) tumours and was present only in scattered cases in the other groups. PLCs and ILCs were strongly positive for bcl-2 and for hormone receptors, while p53+ cells were rare. IDCs exhibited a heterogeneous staining pattern for bcl-2 and for hormone receptors, while p53+ cells occurred considerably more frequently. Stage could not be linked directly to proliferation or apoptosis.

CONCLUSION

Our data suggest that more frequent over-expression of Her2 among PLCs (G3) as well as the generally low apoptosis can contribute to their aggressive behaviour.

Comparative image and flow cytometric TUNEL analysis of fine needle samples of breast carcinoma

The assessment of apoptosis in solid tumors is of interest because of its biological role in tumor evolution and response to therapy. A commonly used method for apoptosis measurement is the TUNEL 3' end-labeling technique, which has shown wide variations in results when applied to solid tumors. Thirty-one fine needle breast carcinoma samples were analyzed by fluorescent TUNEL assay and DNA content using image analysis and flow cytometry. TUNEL positivity, seen both in cells with apoptotic morphology and in a subset of morphologically normal cells, was categorized into five staining patterns and quantitated. Values for patterns of TUNEL-positive cells were compared with TUNEL positivity measured by flow cytometry. Flow cytometric quantitation showed a mean of 24.3% positive cells, which correlated (P < 0.02) with total positive cells (all patterns) measured by image (22.4%). Image analysis quantitation of morphologically apoptotic cells (4.2%) did not correlate with flow cytometric TUNEL positivity and the majority of TUNEL-stained cells were morphologically normal (17%). Image analysis allows discrimination of TUNEL-positive morphologically apoptotic and nonapoptotic cells, which are included in the total number of TUNEL-positive events measured by flow cytometry.

Apoptosis and expression of Bcl-2 and Bax proteins in invasive ductal carcinoma of the pancreas

The Bcl-2 family of genes plays important roles in the regulation of apoptosis. The present study was designed to assess the clinicopathologic significance of apoptosis and the expression of the apoptosis-inhibitory Bcl-2 protein (pBcl-2) and the apoptosis-promoting Bax protein (pBax) in human invasive ductal carcinomas (IDCs) of the pancreas. The present study included 66 IDCs that were resected between 1982 and 1998. Apoptosis was assessed by the in situ nick end labeling method and pBcl-2 and pBax were stained immunohistochemically. Apoptosis was quantified as the apoptotic index (AI, the percentage of apoptotic cells of the total tumor cells), and a high AI (>10%) was observed in 26 of the 66 (39%) IDCs. The AI correlated significantly with the extent of nodal involvement. pBax immunoreactivity was detected in 42 of 66 IDCs (64%), and pBax expression was significantly correlated with female gender and showed a significant negative correlation with the extent of nodal involvement. pBcl-2 was expressed in 16 IDCs (24%) but did not show any correlation with the clinicopathologic factors. The AI did not correlate with the expression of pBcl-2 or pBax, but there was a significant correlation between the expression of pBcl-2 and that of pBax; 15 of the 16 pBcl-2(+)IDCs were also pBax(+), and only one pBcl-2(+)IDC was pBax(-). Univariate analysis demonstrated that the degree of apoptosis had no significant influence on the patients' prognosis, pBax or pBcl-2 expression was significantly associated with a better prognosis, and in particular, the pBax(+)pBcl-2(+) group had a significantly higher survival than the other groups. On the other hand, the survival curve of the adjuvant chemotherapy (ACT) group was also higher than that of the surgery alone (SA) group, with borderline statistical signfiicance. The ACT group showed a significantly better survival rate than the SA group for the pBax(+)IDC patients, but the AI and pBcl-2 expression were not correlated with an improved survival rate in the ACT group. Multivariate analysis showed that the AI. pBcl-2 expression, and pBax expression by themselves did not represent significant variables for death owing to IDC, but pBax expression was significantly associated with the efficacy of ACT. In conclusion, pBax expression may be essential for pBcl-2 expression. pBcl-2 and pBax expressions are not significant prognostic factors for patients with IDC, but pBax expression may be beneficial in predicting the effects of ACT on patients with IDC.

Clinical outcome and bromodeoxyuridine-derived proliferation indices in 75 invasive breast carcinomas

INTRODUCTION

In vivo labelling of human breast tumours with bromodeoxyuridine (BrdUrd) and analysis by flow cytometry (FCM) allows the labelling index (LI), S phase duration (t(s)) and the potential doubling time (t(pot)) of the tumour to be estimated.

METHODS

The data for a series of tumour specimens from 75 patients with invasive breast carcinoma were reported in 1991, correlated with their lymph-node status, tumour size and grade.

RESULTS AND CONCLUSIONS

This study reports the follow-up data over 10 years in respect of time to recurrence and death from the disease. There were no significant correlations between proliferation data and outcome measures. No adverse events were identified which could be attributed to the use of the halogenated pyrimidine label in vivo.

Ovarian endometriosis associated with ovarian carcinoma: a clinicopathological and immunohistochemical study

OBJECTIVE

The purpose of this study was to demonstrate the incidence, the histopathological characteristics, and the proliferation activity of endometriosis and atypical endometriosis associated with ovarian carcinoma.

METHODS

Microscopic slides of primary lesions from 127 patients with primary ovarian carcinoma were reviewed. The presence or absence of endometriosis and the transitions from typical endometriosis to atypical endometriosis and from atypical endometriosis to carcinoma were also histologically evaluated. Ki-67 immunoreactivity of typical and atypical endometriosis and carcinoma was examined. In addition, endometrial metaplasias were also evaluated.

RESULTS

Of the 127 patients, 37 had endometriosis: 70% (30/43) had clear cell adenocarcinoma, 43% (3/7) had endometrioid adenocarcinoma, 7% (4/60) had serous adenocarcinoma, and none (0/17) had mucinous adenocarcinoma. Thirty-three cases showed typical endometriosis and 29 cases had atypical endometriosis (25 cases had both). Tufting and the stratification of the lining epithelium were observed in 25 and 23 cases, respectively. The transition from typical endometriosis to atypical endometriosis was observed in 22 cases, and the transition from atypical endometriosis to carcinoma, in 23 cases. Only one case showed a direct transition from typical endometriosis to carcinoma. The mean Ki-67 indices were as follows: ovarian carcinoma, 23.1; atypical endometriosis, 9.9; typical endometriosis, 2.7. In 18 cases with metaplasia in endometriosis, eosinophilic metaplasia and ciliated metaplasia were the most common types. Five cases had two types of metaplasia.

CONCLUSIONS

Ovarian carcinomas, especially clear cell and endometrioid adenocarcinomas, are highly associated with endometriosis. Atypical endometriosis shows proliferation activity intermediate to those of typical endometriosis and ovarian carcinoma, suggesting it is a precancerous status.

Sex hormone-induced mammary carcinogenesis in the female Noble rats: expression of bcl-2 and bax in hormonal mammary carcinogenesis

We have established a Noble rat model to explore the mechanisms of hormonal mammary carcinogenesis, in which the role of androgen in promoting mammary carcinogenesis was highlighted. We have also established that stromal-epithelial interactions may be responsible for the promotional effects of testosterone in mammary carcinogenesis. Based on these understandings, in the present study we examined the expression of Bcl-2 and Bax in pre-malignant mammary glands from rats treated with different protocols of sex hormones for 7 weeks as well as sex hormone induced mammary tumours. We observed that Bcl-2 was strongly expressed in most of mammary tumour cells, whereas weak or negative in adjacent normal or hyperplastic ductal structures. On the contrary, Bax immunoreactivity was weak in mammary tumour cells while strongly expressed in adjacent normal or hyperplastic ductal structures. More importantly, the results from comparative study of 'pre-malignant' glands further showed that when animals were treated with 17beta-oestradiol, the mammary epithelial cells expressed high levels of Bcl-2. The results from rats treated with testosterone, either alone or in combination with oestrogen, give rise to high levels of Bax expression in 'pre-malignant' mammary glands. These observations indicate that in 'pre-malignant' mammary glands, treatment with testosterone, either alone or in combination with 17beta-oestradiol, may induce high apoptotic activities. However, in fully developed mammary tumours, the apoptotic activities apparently decrease in tumour cells. TUNEL assay provides further data to support this conclusion. Our study, thus, suggests that androgens may play a promoting role in mammary carcinogenesis by upregulation of Bax expression and induction of high apoptotic activities in 'pre-malignant' stage, which would provide a selective pressure favouring the expansion of the initiated cells.

Glycogen-rich carcinomas of the breast display unique characteristics with respect to proliferation and the frequency of oligonucleosomal fragments

We determined the proliferation rate and apoptotic activity of glycogen-rich carcinomas of the breast as opposed to non-clear cell tumors by means of MIB-1 immunohistochemistry and in situ detection of oligonucleosomal fragments (TUNEL reaction). The retrospective biopsy series included six invasive clear cell carcinomas of the glycogen-rich type as well as 15 randomly selected cases of invasive ductal carcinoma without evidence of glycogen storage. Three patients in the clear cell group and seven patients in the control cohort developed lymph-node metastasis. The MIB-1 labeling index of glycogen-rich carcinomas averaged 9.05%, while that of the controls was 30.03%. Apoptotic nuclei were present in a mean of 1.26% of glycogen-rich carcinoma cells. The control tumors exhibited an average apoptotic frequency of 5.85%. Tumor size, hormone receptor status, and presence or absence of lymph node involvement were found not to correlate with either proliferation or apoptosis. We conclude that glycogen-rich breast carcinomas are characterized by a peculiar 'low proliferation-low apoptosis' cell kinetic profile. The aggressive clinical behavior of these neoplasms may possibly be accounted for by an ineffective apoptotic elimination of otherwise slowly proliferating tumor cells.

Premalignant breast lesions: role for biological markers in predicting progression to cancer

Biological markers associated with in situ carcinoma and atypical intraductal hyperplasia in the breast are examined to help in identifying a subgroup of premalignant lesions whose natural history may be influenced by epigenetic factors. The biomarkers may be used as indices in clinical trials aiming to assess the effect of weight reduction, dietary intervention or hormone replacement therapy on the risk of progression to invasive breast cancer. In the current state of knowledge, the expression of oestrogen receptors, p53, bcl-2 and HER-2 neu oncogenes and the Ki-67 index of proliferative activity, are the most useful biomarkers for this purpose. In situ carcinoma of the breast manifests a variety of morphological phenotypes with specific biological characteristics. There is evidence that only a proportion of premalignant lesions are committed to progression to invasive cancer while other lesions undergo spontaneous regression at the time of the menopause. Cross-cultural studies suggest that it is the late-stage epigenetic promoting factors which are responsible for the high incidence of postmenopausal breast cancer in Western women. Obesity in middle life and the Western diet favour the development of hyperinsulinaemic insulin resistance, and the metabolic-endocrine effects of its concomitants may promote mammary carcinogenesis around the time of the menopause and increase the incidence of invasive cancer after the menopause. Because biomarker changes in premalignant lesions are nearer in time to these promoting influences, they could provide intermediate endpoints for testing the hypothesis.