Prognostic significance of HER-2/neu overexpression in stage I adenocarcinoma of lung

BACKGROUND: Even with early diagnosis and adequate resection, the 5-year survival rate for stage I lung cancer patients is around 60% to 70%. Overexpression of HER-2/neu protein is associated with poor prognosis in lung cancers. In this study, we evaluated the expression of HER-2/neu in cancer cells of lung and assessed their clinicopathologic and prognostic significance. METHODS: From 1986 to 1995, clinical data on 42 consecutive patients who underwent complete surgical resection for stage I lung adenocarcinoma were collected. Expression of HER-2/neu in paraffin-embedded tumor samples was determined by immunohistochemistry and scored with a semiquantitative method. RESULTS: Twenty-one of 42 patients were positive for HER-2/neu overexpression in tumor. Compared with patients with low HER-2/neu expression, patients with HER-2/neu overexpression had a significantly higher incidence of early tumor recurrence (p = 0.014). Survival was also significantly better in patients without HER-2/neu overexpression than in those with HER-2/neu overexpression (p = 0.0047). By univariate analysis, HER-2/neu overexpression and poor cell differentiation are two important factors correlated with poor prognosis. CONCLUSIONS: Expression of HER-2/neu oncoprotein in stage I lung adenocarcinoma can predict the tumor's aggressiveness. Early tumor recurrence was frequently detected in patients with HER-2/neu overexpression. We recommend an individualized therapeutic strategy based on the level of HER-2/neu oncoprotein in the tumor cells.     

High-titer HER-2/neu protein-specific antibody can be detected in patients with early-stage breast cancer

PURPOSE: To evaluate HER-2/neu-specific antibody immunity in patients with breast cancer, to determine the rate of occurrence of serum antibodies to HER-2/neu in patients with breast cancer, and to relate the presence of specific immunity to overexpression of HER-2/neu protein in primary tumor. METHODS: The antibody response to HER-2/neu protein was analyzed in 107 newly diagnosed breast cancer patients. Sera was analyzed for the presence of HER-2/neu-specific antibodies with a capture enzyme-linked immunosorbent assay (ELISA) and verified by Western blot. Sera from 200 volunteer blood donors was used as a control population. RESULTS: The presence of antibodies to HER-2/neu correlated with the presence of breast cancer. HER-2/neu antibodies at titers of > or = 1:100 were detected in 12 of 107 (11%) breast cancer patients versus none of 200 (0%) normal controls (P < .01). The presence of antibodies to HER-2/neu also correlated to overexpression of HER-2/neu protein in the patient's primary tumor. Nine of 44 (20%) patients with HER-2/neu-positive tumors had HER-2/neu-specific antibodies, whereas three of 63 (5%) patients with HER-2/neu-negative tumors had antibodies (P = .03). The antibody responses could be substantial. Titers of greater than 1:5,000 were detected in five of 107 (5%). CONCLUSION: The presence of HER-2/neu antibodies in breast cancer patients and the correlation with HER-2/neu-positive cancer implies that immunity to HER-2/neu develops as a result of exposure of patients to HER-2/neu protein expressed by their own cancer. These findings should stimulate further studies to develop the detection of immunity to oncogenic proteins as tumor markers, as well as the development and testing of vaccine strategies to induce and augment immunity to HER-2/neu for the treatment of breast cancer or prevention of recurrent disease.     

The HER-2/neu oncogene in breast cancer: prognostic factor, predictive factor, and target for therapy

To examine whether and how local somatothermal stimulation inhibits the function of the sphincter of Oddi (SO) in humans and in animals with different types of SO, we measured the activity of SO in anesthetized cats and rabbits by using continuously perfused open-tip manometric methods. Local somatothermal stimulation was achieved by applying an electroheating rod 0.5 cm away from the skin area near the right subcostal region. A heating pad was applied to the corresponding area in patients undergoing endoscopic retrograde cholangiopancreatography and biliary manometry. The motility of the biliary tract in cats, in terms of gall bladder pressure, tonic and phasic contraction pressure and frequency of SO before and during local heat were significantly different, respectively. The local heat-induced SO relaxation was not inhibited by pretreatment with atropine, propranolol, phentolamine or anti-cholecystokinin-octapeptide, but was almost completely blocked by infiltration of local anesthetics. Pretreatment with a nitric oxide synthesis inhibitor also blocked the relaxation, which was reversed by pretreatment with L-arginine, but not by D-arginine. The inhibition of SO motility by local heat in rabbits was also blocked by pretreatment with L-NAME, and this blockade was reversed by L-arginine. Application of local heat on patients demonstrated obvious inhibitory SO responses. We conclude that local somatothermal stimulation inhibits the SO motility in animals with different types of SO through the activation of heat-sensitive neural release of nitric oxide. This procedure may represent a simplified approach for the treatment of diseases with hypofunction of the L-arginine/NO pathway.     

Reduced drug accumulation and multidrug resistance in human breast cancer cells without associated P-glycoprotein or MRP overexpression

MCF-7 human breast cancer cells selected in Adriamycin in the presence of verapamil developed a multidrug resistant phenotype, which was characterized by as much as 100,000-fold resistance to mitoxantrone, 667-fold resistance to daunorubicin, and 600-fold resistance to doxorubicin. Immunoblot and PCR analyses demonstrated no increase in MDR-1 or MRP expression in resistant cells, relative to parental cells. This phenotype is similar to one previously described in mitoxantrone-selected cells. The cells, designated MCF-7 AdVp, displayed a slower growth rate without alteration in topoisomerase II alpha level or activity. Increased efflux and reduced accumulation of daunomycin and rhodamine were observed when compared to parental cells. Depletion of ATP resulted in complete abrogation of efflux of both daunomycin and rhodamine. No apparent alterations in subcellular daunorubicin distribution were observed by confocal microscopy. No differences were noted in intracellular pH. Molecular cloning studies using DNA differential display identified increased expression of the alpha subunit of the amiloride-sensitive sodium channel in resistant cells. Quantitative PCR studies demonstrated an eightfold overexpression of the alpha subunit of the Na+ channel in the resistant subline. This channel may be linked to the mechanism of drug resistance in the AdVp cells. The results presented here support the hypothesis that a novel energy-dependent protein is responsible for the efflux in the AdVp cells. Further identification awaits molecular cloning studies.     

Study of Her-2/neu oncogene in relation to prognosis of human breast cancer

A follow-up study of 143 cases of human breast cancer for over 5 years proved that Her-2/neu oncogene overexpression is much more common in the high risk group (patients died within 5 years) in comparison with the low risk group (patients survived over 5 years). The difference between these 2 groups was statistically significant. The Her-2/neu oncogene positive rate in infiltrative ductal carcinoma was 33.3%, the lower the differentiation, the higher the positive rate. Histological typing is also related to the positive rate, comedocarcinoma (intraductal carcinoma) expresses the highest positive rate while lobular carcinoma the lowest. Selection of fixation fluid and the mastering of diagnostic criteria are also important. In the author's opinion, only membrane staining in monoclonal antibody C-erbB-2 can be recognized as truly positive. In conclusion, Her-2/neu oncogene expression can be used as a supplemental marker when considering prognosis in breast cancer.     

Quantitation of HER-2/neu and c-myc gene amplification in breast carcinoma using fluorescence in situ hybridization

HER-2/neu and c-myc amplification or overexpression have been reported to be associated with poor prognosis in breast carcinoma. The prognostic significance, however, remains somewhat controversial, partly because of discrepancies among different methodologies used for detection of the oncogene amplification or overexpression. Fluorescence in situ hybridization (FISH) has recently been shown to be a useful technique for analyzing genetic alterations in interphase nuclei in various tumors. In this study, FISH was used to quantitate HER-2/ neu and c-myc gene amplification in touch preparations of frozen tissue from 100 node-negative breast carcinomas. HER-2/neu amplification was found to be associated with an abnormal DNA index (P < .001) and tumor size (P < .04). Amplification of c-myc was associated with S phase (P < .0003), abnormal DNA index (P < .003), and a negative estrogen receptor status (P < .01). The coamplification of both oncogenes was strongly associated with an abnormal DNA index (P < .0001) and with tumor size (P < .009). The use of FISH for detection of HER-2/neu gene amplification was 92% concordant with immunocytochemistry (ICC) used for detection of overexpression of HER-2/neu protein. Fifteen of the 100 cases were both amplified for HER-2/neu by FISH and positive by ICC analysis. Seven cases without HER-2/neu gene amplification demonstrated HER-2/neu protein overexpression by ICC. One HER-2/neu-amplified case was negative by ICC. Repeat analysis of a subset of cases showed FISH to be a more reproducible method than ICC in the analysis of HER-2/neu in touch preparations of breast carcinoma. FISH is a rapid and reproducible method that allows the accurate measurement of the level of oncogene amplification within interphase nuclei. The use of FISH should provide a more accurate assessment of the prognostic significance of oncogene amplification in breast carcinoma.     

NH2-terminally truncated HER-2/neu protein: relationship with shedding of the extracellular domain and with prognostic factors in breast cancer

We identified an NH2-terminally truncated HER-2/neu product of M(r) 95,000 with in vitro kinase activity by Western blotting and immunoprecipitations using domain-specific antibodies. p95 levels correlated with the extracellular domain (ECD) shed from different cells under varied conditions. Both ECD and p95 were at approximately 20-fold lower levels in SKOV3 ovarian carcinoma cells, as compared to BT474 breast carcinoma cells. Both were stimulated by treatment of cells with the phorbol ester tumor promoter phorbol 12-myristate 13-acetate and the lysosomotrophic agent chloroquine. The hydroxamate inhibitor of metalloproteases, TAPI, suppressed both p95 and ECD in a dose-dependent fashion, with maximal inhibition at < or = 10 microM in BT474 cells. Cancer tissues were analyzed by Western blotting and scored for p95HER-2/neu and for p185HER-2/neu expression. Breast and ovarian cancer tissues were both found to express p95HER-2/neu in addition to p185HER-2/neu. Of 161 breast cancer tissues, 22.4% expressed p95, 21.7% overexpressed p185, and 14.3% were p95 positive and overexpressed p185. A higher proportion of node-positive patients (23 of 78) than node-negative patients (9 of 63) expressed p95 in all tumors combined (P = 0.032). In the group that overexpressed p185, those that contained p95 were associated with node-positive patients (15 of 21), whereas those that were p95 negative were associated with node-negative patients (8 of 11; P = 0.017). Neither p95- nor p185-rich patients significantly correlated with tumor size or with hormone receptor status in this study. Our findings show that breast cancers, which express the HER-2/neu oncogene, are heterogeneous with respect to HER-2/neu protein products. p95HER-2/neu appears to distinguish tumors that have metastasized to the lymph nodes from those in node-negative patients.     

Estrogen receptor, progesterone receptor, and HER-2/neu protein in breast cancers from pregnant patients

BACKGROUND: Because the occurrence of breast cancer during pregnancy is uncommon and because the high levels of estrogens and progestins associated with pregnancy could cause false-negative results from ligand binding assays (LBA), the actual incidence of steroid hormone receptor positivity in tumors from this subset of women is unclear. METHODS: Estrogen receptor (ER) and progesterone receptor (PgR) were determined using LBA methods in 15 tumors from 15 pregnant patients with breast cancer. In addition, immunohistochemistry was done for ER, PgR, pS2, heat shock protein 27 (hsp27), and HER-2/neu on 12 of the 15 tumors. RESULTS: Five of 15 (33%) tumors were positive for ER by LBA, compared with 52% of tumors from age-matched nonpregnant patients. Six of 12 (50%) were ER-positive by immunohistochemistry. For PgR, 7 of 15 (47%) tumors were positive by LBA, compared with 42% of tumors from nonpregnant patients. Ten of 12 (83%) stained positive for PgR. By LBA, 67% of tumors studied were positive for ER or PgR or both, as opposed to 57% of tumors from the nonpregnant comparison group. Two other estrogen receptor-mediated proteins, pS2 and hsp27, were present by staining in 8 of 12 (67%) and 10 of 12 (83%) of tumors, respectively. Seven of 12 tumors (58%) had positive staining for HER-2/neu, whereas only 16% of age-matched nonpregnant patients had positive-staining tumors. CONCLUSION: By LBA, the incidence of ER and PgR in breast tumors from pregnant women was not significantly different from that of tumors from nonpregnant age-matched patients. Some ER-negative tumors were PgR, pS2, or hsp27 positive, indicating that an intact estrogen response system was operative although ER was not detectable by standard LBA.     

Increased natural killer cell activity correlates with low or negative expression of the HER-2/neu oncogene in patients with breast cancer

BACKGROUND: Increased expression of the HER-2/neu oncogene in breast cancer correlates with decreased estrogen receptor concentration and seems to be an important prognostic factor. The authors investigated whether there is a correlation between HER-2/neu expression and immunologic parameters representing tumor defense in patients with breast cancer. METHOD: A Western blot analysis was used to investigate HER-2/neu expression, whereas a chromium-release assay using the K562 cell line as target was used to measure natural killer (NK) cell activity. RESULTS: In patients with breast cancer, NK cell activity was significantly higher compared with patients with benign tumors (P = 0.006) or healthy control subjects (P = 0.002). Moreover, 23.3% of patients with breast cancer showed an overexpression of HER-2/neu protein. Within this group of patients, NK cell activity was significantly lower (45.6 +/- 16.1%) compared with the group with no HER-2/neu overexpression (57.3 +/- 11.0%). NK cell activity did not increase in patients with HER-2/neu overexpression. Thus, there was a statistically significant correlation of cytolytic effector cell function with HER-2/neu expression of the tumor (P = 0.003), and HER-2/neu overexpression correlated with a negative estrogen receptor status (P = 0.005). CONCLUSION: These data add further evidence to previous observations from the authors' laboratory that certain tumor characteristics may be associated with reactions of the host with breast cancer.     

HER-2/neu gene amplification characterized by fluorescence in situ hybridization: poor prognosis in node-negative breast carcinomas

PURPOSE: The HER-2/neu gene codes for a membrane receptor protein that is homologous, but distinct from the epidermal growth factor receptor. This investigation was performed to validate fluorescence in situ hybridization (FISH) as a sensitive and specific method for assessing HER-2/neu gene amplification in archival tissue and to test whether this alteration is associated with poor prognosis. MATERIALS AND METHODS: HER-2/neu gene amplification was determined by FISH in 140 archival breast cancers, previously characterized for gene amplification by Southern hybridization or dot-blot hybridization, and for gene expression by Northern hybridization, Western immunoblot, or immunohistochemistry. A separate cohort of 324 node-negative breast cancers was assessed for amplification by FISH to determine the utility of HER-2/neu gene amplification. RESULTS: Relative to solid-matrix blotting procedures, FISH analysis of HER-2/neu gene amplification showed a sensitivity of 98% and a specificity of 100% in 140 breast cancers. Among patients treated by surgery only, the relative risks (relative hazard) of early recurrence (recurrent disease within 24 months of diagnosis), recurrent disease (at any time), and disease-related death were statistically significantly associated with amplification. The prognostic information contributed by HER-2/neu amplification was independent of the other markers studied. CONCLUSION: FISH was an alternative technique for determining gene amplification and had some distinct advantages over Southern hybridization. Our results demonstrate that HER-2/neu gene amplification in the absence of adjuvant therapy is an independent predictor of poor clinical outcome and is a stronger discriminant than tumor size. Women with small tumors that had gene amplification were at increased risk of recurrence and disease-related death.     

Expression of HER-2/neu oncogene in normal, hyperplastic, and malignant endometrium

The development of new technologies in neonatal intensive care which appeared this last decade increased the viability of premature newborns and contributed to the increase in the number of admissions of very low birth weight (VLBW) newborns in the intensive neonatal care services (12.6% of admissions in 1987, 15.2% in 1996). In a retrospective epidemiology survey in French speaking Belgian Community, we collected the data of 1521 newborns whose birth weight was under 1500 g, from January 1990 to December 1994, in order to improve our knowledge or regional mortality and morbidity rates and to estimate the impact of new procedures. We do not notice any variation of annual mortality (+/- 20%), nor of morbidity (sequelae risks to survivors at the departure of the hospital +/- 23%) on the global population during the survey period. However the mortality of infants born between 30 and 33 weeks drops dramatically (17% in 1990, 3.6% in 1994). As it has been demonstrated in randomised surveys, we recover the beneficial effect of antenatal corticotherapy which allows us to reduce to more than 50% the mortality of newborns from treated mothers (11% mortality versus 24%). In comparison to figures of international literature, our survival rate without sequelae is at least 10% lower than Américan results for infants whose birth weight is < 1000 g and at least 5% lower for infants between 1000 and 1500 g. In conclusion, although the introduction of surfactant and high frequency ventilation during this period, mortality rate of VLBW infants doesn't seem to decrease significantly from 1990 to 1994. However, multivariate statistical study of predictable mortality and morbidity factors need to be performed in order to define or promote preventive strategy.     

Correlation of p34cdc2 cyclin-dependent kinase overexpression, CD44s downregulation, and HER-2/neu oncogene amplification with recurrence in prostatic adenocarcinomas

PURPOSE: To test whether p34cdc2 overexpression, CD44s downregulation, and HER-2/neu amplification correlate with disease recurrence after radical prostatectomy, and to evaluate a possible biologic association between p34cdc2 and HER-2/neu expression. MATERIALS AND METHODS: Immunohistochemical (IHC) detection of both p34cdc2 cyclin-dependent kinase (CDK) and CD44s expression and fluorescence in situ hybridization (FISH)-based analysis of HER-2/neu gene status were performed on formalin-fixed, paraffin-embedded sections of 106 prostatic adenocarcinomas (PACs). Findings were correlated with Gleason grade, pathologic stage, DNA ploidy, and postsurgical biochemical disease recurrence. RESULTS: CDK overexpression correlated with tumor grade (P = .001), DNA ploidy (P = .001), pathologic stage (P = .04), and disease recurrence (P = .01). CD44s downregulation correlated with grade (P = .03), ploidy (P = .01), and recurrence (P = .02). HER-2/neu amplification correlated with grade (P = .001), ploidy (P = .001), and recurrence (P = .01). On multivariate analysis, CDK overexpression independently predicted recurrence (P = .001) after prostatectomy. CDK expression correlated with HER-2/neu status with 32 of 65 (49%) tumors that overexpressed CDK and showed concomitant HER-2/neu amplification (P = .04). CONCLUSION: This study showed that p34cdc2, CD44s, and HER-2/neu are variably expressed or amplified in prostatic carcinoma and that such alteration may affect tumor behavior. In addition, CDK overexpression and HER-2/neu amplification may be biologically related.     

Proliferative and cytokine responses to class II HER-2/neu-associated peptides in breast cancer patients

Previous studies have characterized the reactivity of CD8+ CTLs with ovarian and breast cancer. There is little information about the antigens and epitopes recognized by CD4+ T cells in these patients. In this study, we analyzed the ability of T cells from peripheral blood mononuclear cells of breast cancer patients to recognize HER-2/neu (HER-2) peptides. We found that 13 of 18 patients responded by proliferation to at least one of the HER-2 peptides tested. Of these peptides, one designated G89 (HER-2: 777-789) was recognized by T cells from 10 patients. Seven of nine responding patients were HLA-DR4+, suggesting that this peptide is recognized preferentially in association with HLA-DR4. Analysis of the specificity and restriction of the cytokine responses to G89 by G89-stimulated T cells revealed that these cells secreted significantly higher levels of IFN-gamma than interleukin 4 and interleukin 10, suggesting priming for a Th0-T helper 1 response. The same pattern of cytokine responses was observed to the intracellular domain of HER-2 protein, suggesting that G89-stimulated T cells recognized epitopes of the HER-2 protein in association with HLA-DR4. Because HLA-DR4 is present in 25% of humans, characterization of MHC class II-restricted epitopes inducing Th0-T helper 1 responses may provide a basis for the development of multivalent HER-2-based vaccines against breast and ovarian cancer.     

The effect of the chemotherapeutic drug VP-16 on poly(ADP-ribosylation) in apoptotic HeLa cells

We have studied the effect of the chemotherapeutic drug VP-16 (etoposide) on the metabolism of HeLa cells by analysing different cellular parameters; in particular we have focused on changes in cellular morphology that are considered as markers of apoptosis. By immunofluorescence experiments we have shown that VP-16 causes the complete disruption of nucleoli and induces chromatin margination and fragmentation. Agarose gel electrophoresis of DNA from cells treated with 10-100 microM VP-16 showed the appearance of a characteristic ladder due to the internucleosomal DNA cleavage. The effect of etoposide on DNA integrity was not prevented by preincubation of cells with the protein synthesis inhibitor cycloheximide. These results provide experimental evidence indicating that the typical features of apoptosis are visible in HeLa cells exposed to VP-16. In this experimental system we have investigated whether the ADP-ribosylation process could be regulated by the presence of DNA fragments. By means of the activity gel technique, which allows the direct evaluation of automodified poly(ADP-ribose)polymerase, we have observed that in extracts from cells where etoposide-induced DNA fragmentation occurred, the autoribosylated form of the enzyme is greatly increased. Ribosylated poly(ADP-ribose)polymerase has been isolated by affinity chromatography on boronate column from cells permeabilized and labelled with [32P]NAD. Drug exposure caused a strong augmentation of modified enzyme. These observations suggest that activation of ADP-ribosylation process occurs in cells that show the typical features of apoptosis.     

Remission of human breast cancer xenografts on therapy with humanized monoclonal antibody to HER-2 receptor and DNA-reactive drugs

HER-2 oncogene encodes a transmembrane growth factor receptor that is overexpressed in 25-30% of patients with primary breast and ovarian cancer. A murine monoclonal antibody, 4D5, to the extracellular domain of HER-2 receptor elicits cytostatic growth inhibition of tumor cells overexpressing HER-2 protein, but clinical use of this antibody is limited by genesis of human anti-mouse antibodies. To avoid this problem, a recombinant humanized 4D5 monoclonal antibody (rhuMAb HER-2) was developed and tested using a human tumor xenograft model. Human breast and ovarian cancer cells which overexpress HER-2 were inhibited in vivo by the rhuMAb HER-2 antibody. Tumor growth relative to control was reduced at all doses of antibody tested, and the magnitude of growth inhibition was directly related to dose of rhuMAb HER-2. Tumor growth resumed on termination of antibody therapy, indicating a cytostatic effect. To elicit a cytotoxic response, human breast tumor xenografts were treated with a combination of antibody and antitumor drugs, cisplatin or doxorubicin. The combination of antibody with either cisplatin or doxorubicin resulted in significantly greater growth inhibition, with the cisplatin combination demonstrating a greater response. In addition, therapy with cisplatin and antireceptor antibody elicited complete tumor remissions after 2-3 cycles of therapy. The schedule of administration of anti-receptor antibody and cisplatin was critical for occurrence of antibody-induced potentiation in cisplatin cytotoxicity. Enhanced killing of tumor cells was found only if antibody and drug were given in close temporal proximity. Since interference with DNA repair pathways may contribute to this receptor-enhanced chemosensitivity, repair of cisplatin-damaged reporter DNA (pCMV-beta) was determined in human breast cells. As in studies of antibody-enhanced cisplatin cytotoxicity in vivo, treatment with rhuMAb HER-2 blocked the repair of cisplatin-damaged DNA only if the antibody was administered in close temporal proximity to transfection of the drug-exposed reporter DNA. An alternative measure of DNA repair, unscheduled DNA synthesis, was also assessed. Treatment with either cisplatin or doxorubicin led to an increase in unscheduled DNA synthesis that was reduced by combined therapy with antireceptor antibody specific to HER-2-overexpressing breast cancer cells. Using a direct measure of DNA repair, therapy of HER-2-overexpressing cells with rhuMAb HER-2 also blocked the removal of cisplatin-induced DNA adducts. Expression of p21/WAF1, an important mediator of DNA repair, was disrupted in breast cancer cells with HER-2 overexpression, but not in control cells, after treatment with HER-2 antibody, thus suggesting cross-communication between the HER-2 signaling and DNA repair pathways. These data demonstrate an in vivo antiproliferative effect of rhuMAb HER-2 on tumors that overexpress HER-2 receptor and a therapeutic advantage in the administration of the antireceptor antibody in combination with chemotherapeutic agents.     

Additive effect of mifepristone and tamoxifen on apoptotic pathways in MCF-7 human breast cancer cells

MCF-7 cells growing in culture were used to study the mechanism of the antiproliferative activity of the antiprogestin mifepristone, as compared with the antiestrogen 4-hydroxytamoxifen or the combination of both. These steroid antagonists induced a significant time- and dose-dependent cell growth inhibition (cytotoxicity). This inhibition of cell survival was associated with a significant increase in DNA fragmentation (apoptosis), downregulation of bcl2, and induction of TGFbeta1 protein. Abrogation of the mifepristone- and/or 4-hydroxytamoxifen-induced cytotoxicity by TGFbeta1 neutralizing antibody confirms the correlation between induction of active TGFbeta1 and subsequent cell death. The effect of a combination of mifepristone and 4-hydroxytamoxifen on cell growth inhibition, on the increase in DNA fragmentation, bcl2 downregulation, and induction of TGFbeta1 protein was additive and significantly different (P < 0.05) from the effect of monotherapy. A translocation of protein kinase C (PKC) activity from the soluble to the particulate and/or nuclear fraction appeared to be also additive in cells treated with a combination of both 4-hydroxytamoxifen and mifepristone. These results suggest that the mechanism of the additive antiproliferative activity of mifepristone and tamoxifen could be explained at least in part by an additive induction of apoptosis in both estrogen and progesterone receptor positive MCF-7 breast cancer cells. A bcl2 downregulation, the PKC transduction pathway, and TGFbeta1 expression seem to be involved in this additive mechanism of action. Our data further suggest that a combination of an antiprogestin with tamoxifen may be more effective than tamoxifen monotherapy in the management of human breast cancer.     

Effect of the antitumor drug lonidamine on glucose metabolism of adriamycin-sensitive and -resistant human breast cancer cells

The efficacies of direct percutaneous transluminal coronary angioplasty (PTCA) and thrombolysis for the treatment of acute myocardial infarction were investigated in 80 patients treated within 12 hours of the onset of myocardial infarction by either PTCA (39 patients) or thrombolytic therapy (41 patients) followed by conservative care. The therapeutic approach was selected according to the treatment strategy at each of the 16 participating centers before the admission of the patients. The two treatment groups were closely matched in clinical characteristics except for the history of hypertension which occurred more in the thrombolysis group (22/39 vs 12/41, p = 0.026). The mean time before starting reperfusion therapy from the onset of symptoms was shorter in the thrombolysis group (2.3 +/- 1.5 vs 5.3 +/- 5.7 hours, p = 0.0001). Chest pain resolved more quickly in the PTCA group. Serial changes in the mean numbers of abnormal Q waves and mean values of the sum of elevated ST-segments on the electrocardiograms were similar in both groups. Serial changes of wall motion abnormality index on echocardiograms were similar in both groups. Coronary angiography after 4 weeks showed the thrombolysis group had greater residual luminal stenosis in the infarct-related artery. Left ventriculography after 4 weeks showed the PTCA group had better mean ejection fraction (68.1 +/- 11.2% vs 58.7 +/- 14.2%, p = 0.0263). Death (3/39 vs 1/41) and cardiac events (6/39 vs 6/41) after 4 weeks were similar in both groups. There was no significant difference in death and cardiac events between these two groups. However, the PTCA group had less severe residual luminal stenosis in the infarct-related artery and better left ventricular function after 4 weeks than the thrombolysis group.     

The protective effect of metallothionein against lipid peroxidation caused by retinoic acid in human breast cancer cells

The treatment of breast cancer by retinoic acid (RA) may be mediated by lipid peroxidation. Expression of metallothionein (MT) in cancer cells, however, can protect against lipid peroxidation by scavenging hydroxyl radicals. In this study, a two-by-six factorial design was used to investigate the interactive effects of all-trans-RA and zinc (Zn)-induced MT on the growth of two human breast cancer cell lines differing in basal expression of MT and estrogen receptors; MCF7 cells express estrogen receptor, BT-20 cells do not. Cells were treated with Zn to induce MT and then treated with six RA concentrations. Cell proliferation, lipid peroxidation, MT protein, MT mRNA and glutathione concentrations were measured. BT-20 cells expressed higher constitutive MT concentrations than MCF7 cells. MT was significantly increased by Zn treatment in BT-20 cells but not in MCF7 cells. Low RA concentrations stimulated growth proliferation but higher concentrations inhibited cell proliferation. Elevated RA concentrations increased lipid peroxidation as measured by thiobarbituric acid reactive substances. There was a significant negative correlation between lipid peroxidation and cell proliferation. Growth inhibition and lipid peroxidation were reduced by Zn pretreatment in BT-20 cells but not in MCF7 cells. RA increased MT levels in both cell lines, which suggests that RA may generate free radicals which will induce MT mRNA expression. Glutathione did not appear to be a significant factor. Therefore, induction of MT by Zn may modulate the growth inhibitory effects of RA in human breast cancer cells. One mechanism of growth inhibition may be through increased lipid peroxidation. Induction of MT by RA may be one explanation for acquired RA resistance in cancer.