Prognostic value of P53 gene mutations in a large series of node-negative breast cancer patients

The most important subgroup of breast cancer patients for which reliable prognostic factors are needed are women without axillary lymph node involvement. Although overall, these patients have a good prognosis, it is known that 20-30% will experience a recurrence of the disease. To determine the prognostic significance of P53 tumor suppressor gene mutation, specimens from 113 primary breast cancers were evaluated for the presence of P53 alterations, as detected by cDNA sequencing of the entire coding sequence of the gene. The median follow-up for patients was 105 months. P53 gene mutation was an independent prognostic marker of early relapse and death. Our results suggest that P53 gene mutations could be an important factor to identify node-negative patients who have a poor prognosis in the absence of adjuvant therapy. Prospective studies should be designed to determine which therapy should be performed in this subgroup of patients.     

bcl-2 but not p53 expression is associated with resistance to chemotherapy in advanced breast cancer

Programmed cell death is an important determinant of the response to chemotherapy. Among the factors controlling this process, a significant role is played by bcl-2 and p53, the expression of which, together with estrogen receptor content and tumor proliferative activity, was investigated by means of immunohistochemistry in 55 advanced breast cancer patients (median age, 60 years; range, 25-71 years). Analysis of bcl-2 expression identified two groups of patients with a significant difference in response rate. A total of 17 patients (31%) responded to chemotherapy (5 had a complete response and 12 had a partial response): 14 of 32 (44%) bcl-2-negative patients (< 40% stained cells) and only 3 of 23 (13%) bcl-2-positive patients (> or = 40% of stained cells; P = 0.019 by Fisher's exact test). The two groups were well balanced in terms of age, performance status, disease-free survival, menopausal status, and type of chemotherapy. bcl-2-negative tumors showed a tendency toward a higher p53 expression and proliferation rate, whereas an excess of bone as the dominant disease site was evident among the bcl-2-positive ones. However, the only variable to result significantly different between the two groups was estrogen receptor expression (P = 0.004). A multivariate logistic regression model showed that bcl-2 maintained its power of discriminating two groups with a different probability of responding to chemotherapy, although the greatest contribution was given by dominant disease site and type of chemotherapy. In conclusion, the results of this study suggest a possible role for bcl-2 in predicting resistance to chemotherapy.     

p53 mutations and overexpressions in Japanese breast cancer

In this paper, we explore the use of a variety of familial transmission tests (and case-control analyses) to screen for allelic associations in simulated marker data of a quality (2 cM map) that will feasibly arise from genomic scans within the next 5-10 years. We demonstrate a form of the transmission-disequilibrium test extended to multiallele systems. The methods used were log-linear and related models implemented largely using standard statistical packages.     

Secondary breast cancer in patients presenting with osteosarcoma: possible involvement of germline p53 mutations

Second malignancies following treatment for osteosarcoma are unusual. Breast cancer occurring in patients with osteosarcoma has been reported following therapeutic chest irradiation. We now report three cases of breast cancer occurring in young women who were successfully treated for osteosarcoma. These women had not received therapeutic chest irradiation and in two of the three women there was no family history of breast cancer. Peripheral blood was available for study from one case. Of import, this case demonstrated a germline mutation in exon 7 of the tumor suppressor gene, p53. The mutation was detected by constant denaturing gradient gel electrophoresis and confirmed by DNA sequencing. In this particular patient, inactivation of the p53 gene may be involved in the development of both the first and second malignancy.     

K-ras and p53 mutations are an independent unfavourable prognostic indicator in patients with non-small-cell lung cancer

We examined 159 consecutive cases of non-small-cell lung cancer (NSCLC) for a mutation at codon 12 of the K-ras gene and for a mutation of the p53 gene occurring in exons 5-8. Eleven (6.9%) had mutations of the K-ras (ras+) and 57 (35.8%) had mutations of the p53 (p53+). There were 95 cases (59.7%) with ras- p53-, seven cases (4.4%) with ras+/p53-, 53 cases (33.3%) with ras-/p53+ and four cases (2.5%) with ras+/p53+. The ras+ group had a worse prognosis than the ras group in all cases and in 107 early-stage cases (stage I-II, P<0.05). The p53+ group had a worse prognosis in 107 early-stage cases (P<0.01), but there was no statistically significant difference when 52 advanced-stage cases (stage III-IV) or all patients were considered. Both ras and p53 mutations were unfavourable prognostic factors in 94 cases with adenocarcinoma, but there was no statistical significance in 57 cases with squamous cell carcinoma. According to Cox's model, the pathological stage, ras mutation and p53 mutation were found to be independent prognostic factors. Our results suggest that ras and p53 mutations were independent unfavourable prognostic markers especially in the early stage of NSCLC or in adenocarcinoma.     

Sensitization to doxorubicin resistance in breast cancer cell lines by tamoxifen and megestrol acetate

Acquired drug resistance is a major factor in the failure of doxorubicin-based chemotherapy in breast cancer. We determined the ability of megestrol acetate and/or tamoxifen to reverse doxorubicin drug resistance in a doxorubicin-resistant breast cancer line (the human MCF-7/ADR). The cytotoxicity of doxorubicin, megestrol acetate, and/or tamoxifen was determined in the sensitive and resistant cell lines utilizing the sulphorhodamine B assay. Tamoxifen alone produced an IC50 (concentration resulting in 50% inhibition of control growth) of 10.6 microM, whereas megestrol acetate alone resulted in an IC50 of 48.7 microM in the MCF-7/ADR cell line. The IC50 of doxorubicin in MCF-7/ADR was 1.9 microM. Neither megestrol acetate alone nor tamoxifen alone at 1 or 5 microM altered the IC50 of doxorubicin. However, the combination of tamoxifen (1 or 5 microM) and megestrol acetate (1 or 5 microM) synergistically sensitized MCF-7/ADR cells. Additionally, megestrol acetate and tamoxifen inhibited iodoarylazidoprazosin binding to P-glycoprotein, and, in their presence, there was an increased doxorubicin accumulation in the MCF-7/ADR cells. Furthermore, the combination of tamoxifen and megestrol acetate had much less effect on the cytotoxicity of doxorubicin in MCF-7 wild-type cells. Clinically achievable concentrations of tamoxifen and megestrol acetate can largely sensitize MCF-7/ADR to doxorubicin. The combination of these three drugs in a clinical trial may be informative.     

p53 mutation and tamoxifen resistance in breast cancer

A substantial portion of patients with estrogen receptor-positive breast cancer fail to respond to estrogen depletion or to the antiestrogen tamoxifen. The molecular changes that lead to tamoxifen resistance and estrogen-independent growth are unknown. To test the hypothesis that a p53 mutation could result in tamoxifen resistance and estrogen-independent growth, the MCF-7 cell line was transfected with p53 cDNA which was mutated at codon 179 (histidine to glutamine). MCF-7 is an estrogen receptor-positive, estrogen-dependent, tamoxifen-sensitive cell line with only wild-type p53. The presence of transfected mutant p53 cDNA was verified by the PCR, and overexpression of p53 protein was assessed by Western blotting. Five separate mutant-transfected clones were selected and tested in subsequent growth experiments. In monolayer culture, there was no consistent evidence of estrogen-independent growth or tamoxifen resistance in the mutant transfectants compared with vector-only controls or the parental cell line. In soft agar growth experiments, four of five mutant transfectants remained sensitive to tamoxifen in a dose-dependent manner. In the presence of wild-type p53, mutant 179 p53 protein does not result in estrogen-independent growth or tamoxifen resistance. These results do not exclude the possibility that other p53 mutational types could result in tamoxifen resistance, or that loss of the remaining wild-type allele may be necessary to result in this phenotype.     

P53 tumour-suppressor gene mutations are mainly localised on exon 7 in human primary and metastatic prostate cancer

Mutations in the p53 tumour-suppressor gene are among the most common genetic alterations in human cancers. In the present study we analysed the mutations in the p53 tumor-suppressor gene in 25 primary and 20 metastatic human prostate cancer specimens. DNA extracted from the paraffin-embedded sections was amplified by hot-start polymerase chain reaction, and p53 gene mutations in the conserved mid-region (exons 4-9) were examined using single-strand conformation polymorphism (SSCP) analysis and immunohistochemistry. In the present study, we used a novel hot-start PCR-SSCP technique using DNA Taq polymerase antibody, which eliminates primer-dimers and non-specific products. Because of this new technique, the results of PCR-SSCP showed very high resolution. Polymerase chain reaction products were sequenced directly for point mutations for the p53 gene. Mutations were found in 2 out of 25 primary prostate cancers (8%) and 4 out of 20 metastatic cancers (20%). Mutations were observed exclusively in exon 7 and not in exons 4, 5, 6, 8 or 9. Nuclear accumulation of p53 protein, determined by immunohistochemistry, correlated with the degree of metastasis in prostatic cancer.     

Germline mutations in PTEN are an infrequent cause of genetic predisposition to breast cancer

Spinal extradural abscess is an infrequent, but serious complication to extradural catheters. Early diagnosis is essential for successful treatment. An extradural abscess may develop slowly over days to several weeks and symptoms may be vague and unspecific, delaying correct diagnosis. Meticulous supervision of the patients is required and must continue as long as an epidural catheter is in place and for some time after the catheter has been withdrawn. This case report describes a patient undergoing extensive reconstructive plastic surgery after a leg trauma. For postoperative pain treatment a continuous epidural infusion of bupivacaine was given. After 10-14 days an extradural abscess developed with increasing low back pain but without any neurologic symptoms. With antibiotics a complete resolution of the extradural abscess occurred, documented by computerized tomography (CT).     

P53 mutations, asset or disadvantage for cancer chemotherapy]

The "guardian of the genome" p53 is an essential modulator of the cellular response to cytotoxic agents. After introduction of DNA damages, the p53 protein prevents the cells to divide, either transiently by arresting their progression at the G1/S transition, or definitely by inducing apoptosis. In approximately half of the human tumors, mutations result in profound alterations of the p53 protein properties. In this work, the consequences of these alterations on the tumor cell sensitivity to chemotherapy are discussed.     

erbB-2 and response to doxorubicin in patients with axillary lymph node-positive, hormone receptor-negative breast cancer

BACKGROUND: Overexpression of the erbB-2 protein by breast cancer cells has been suggested to be a predictor of response to doxorubicin. A retrospective study was designed to test this hypothesis. METHODS: In National Surgical Adjuvant Breast and Bowel Project protocol B-11, patients with axillary lymph node-positive, hormone receptor-negative breast cancer were randomly assigned to receive either L-phenylalanine mustard plus 5-fluorouracil (PF) or a combination of L-phenylalanine mustard, 5-fluorouracil, and doxorubicin (PAF). Tumor cell expression of erbB-2 was determined by immunohistochemistry for 638 of 682 eligible patients. Statistical analyses were performed to test for interaction between treatment and erbB-2 status (positive versus negative) with respect to disease-free survival (DFS), survival, recurrence-free survival (RFS), and distant disease-free survival (DDFS). Reported P values are two-sided. RESULTS: Overexpression of erbB-2 (i.e., positive immunohistochemical staining) was observed in 239 (37.5%) of the 638 tumors studied. Overexpression was associated with tumor size (P=.02), lack of estrogen receptors (P=.008), and the number of positive lymph nodes (P=.0001). After a mean time on study of 13.5 years, the clinical benefit from doxorubicin (PAF versus PF) was statistically significant for patients with erbB-2-positive tumors--DFS: relative risk of failure (RR)=0.60 (95% confidence interval [CI]=0.44-0.83), P=.001; survival: RR=0.66 (95% CI=0.47-0.92), P =.01; RFS: RR=0.58 (95% CI=0.42-0.82), P=.002; DDFS: RR=0.61 (95% CI=0.44-0.85), P=.003. However, it was not significant for patients with erbB-2-negative tumors-DFS: RR=0.96 (95% CI=0.75-1.23), P=.74; survival: RR =0.90 (95% CI=0.69-1.19), P=.47; RFS: RR=0.88 (95% CI=0.67-1.16), P=.37; DDFS: RR=1.03 (95% CI=0.79-1.35), P=.84. Interaction between doxorubicin treatment and erbB-2 overexpression was statistically significant for DFS (P=.02) and DDFS (P=.02) but not for survival (P= .15) or RFS (P=.06). CONCLUSIONS: These data support the hypothesis of a preferential benefit from doxorubicin in patients with erbB-2-positive breast cancer.     

TP53 DNA contact mutations are selectively associated with allelic loss and have a strong clinical impact in head and neck cancer

Recent studies have suggested that different mutation types within the core domain of the tumour suppressor protein p53, i.e. DNA contact mutations and structural mutations, confer different biological properties. We have analysed in 86 head and neck squamous cell carcinomas (HNSCC), whether these p53 mutation types have a differential clinical impact. Thirty-seven missense mutations were identified. Thirteen of these (36%) were DNA contact mutations, occurring in the L3 loop, in the H2 loop sheet helix motif, in the S10 beta strand and in Zinc binding residues. Microsatellite marker analysis revealed a selective association between these mutations and the loss of wild-type alleles (100% LOH vs 50% LOH in tumours with structural mutations; P=0.0034, Fisher's exact, 2-tailed). In comparison to structural mutations or to the absence of mutations in the core domain, DNA contact mutations were associated with higher tumour stages (84.6% vs 62%), a higher incidence of lymph node metastasis (91.7% vs 56%; P=0.014, Fisher's exact, 2-tailed), a shortened recurrence-free survival (8.1 months vs 23.7 months, P=0.047, log rank test) and overall survival (11 months vs 29.2 months; P=0.003, log rank test). The latter was also the case when only stage IV tumours were analysed (P=0.0055, log rank test). These data indicate that in HNSCC, TP53 DNA contact mutations confer a strong selection pressure to eliminate wild-type alleles, and that they result in an accelerated tumour progression and reduced therapeutic responsiveness.     

Levels of multidrug resistance (MDR1) P-glycoprotein expression by human breast cancer correlate with in vitro resistance to taxol and doxorubicin

Time lapse video microscopy is used to study the chronology of morphological changes and commitment to die in individual PC12 cells after induction of apoptosis. Cell death is highly asynchronous occurring over a 2- to 3-day period following serum removal; however, all cells go through three characteristic morphological phases irrespective of the time they die following serum removal. During phase 1, which lasts from 2 to 44 h, cells maintain normal morphology. Phase 2 is characterized by plasma membrane bubbling which lasts from 10 min to 40 h. Phase 3 represents the active or execution phase of apoptosis and involves dynamic whole cell body blebbing. Phase 3/execution phase has a restricted duration, lasting 96 +/- 5 min. At the end of the execution phase of apoptosis, cells die. The inherently asynchronous nature of cell death is still present in cells that are synchronized following mitosis. Daughter cells enter phase 2 synchronously but remain in phase 2 for varying periods and die at different times. Addition of serum 24-48 h after initiating apoptosis blocks death of 89% of cells in phase 1, 79% in phase 2, and 0% in phase 3. Serum rescue experiments are consistent with cells committing to die about 2-3 h prior to the onset of phase 3 (execution phase of apoptosis). These studies indicate that although apoptosis is an asynchronous process it can be defined in terms of reproducible morphological changes that can be used to place other events, such as the commitment to die, in a temporal sequence.     

p53 and c-erbB-2 as markers of resistance to adjuvant chemotherapy in breast cancer

Recent literature suggests that c-erbB-2 and p53 alteration might be linked to drug resistance. This study investigates the relation of c-erbB-2 oncoprotein overexpression and p53 protein accumulation with prognosis in patients with node-positive breast cancer (NPBC) and assesses the modifying effect of these markers on response to short (1-10 courses) or prolonged (> 10 courses) adjuvant chemotherapy. This study is based on 458 patients with NPBC diagnosed from 1980 to 1986, with an average of 10 years of follow-up. Marker expression was evaluated by immunohistochemical analysis on formalin-fixed, paraffin-embedded material with antibodies to c-erbB-2 and p53. c-erbB-2 was expressed in 17.2% of the cases, and 19.1% of the tumors stained positively for p53. By multivariate analysis, women with prolonged adjuvant chemotherapy had better survival than those with a short course of chemotherapy among patients whose tumor lacked c-erbB-2 oncoprotein expression (P = .0245) or p53 protein accumulation (P = .0477). Prolonged chemotherapy, however, was associated with little or no change in survival among patients whose tumor expressed those markers. The present study adds support to the hypothesis linking c-erbB-2 and p53 expression to drug resistance.     

Cardiac effects of adjuvant doxorubicin and radiation therapy in breast cancer patients

PURPOSE: To assess the cardiac effects of two different cumulative doses of adjuvant doxorubicin and radiation therapy (RT) in breast cancer patients. PATIENTS AND METHODS: Two hundred ninety-nine breast cancer patients were prospectively randomized to receive either five cycles (CA5) or 10 cycles (CA10) of adjuvant treatment with cyclophosphamide (500 mg/ m2) and doxorubicin (45 mg/m2) administered by intravenous bolus every 21 days. One hundred twenty-two of these patients also received RT. Estimates of the cardiac RT dose-volume were retrospectively categorized as low, moderate, or high. The risk of major cardiac events (congestive heart failure, acute myocardial infarction) was assessable in 276 patients (92%), with a median follow-up time of 6.0 years (range, 0.5 to 19.4). RESULTS: The estimated risk (95% confidence interval) of cardiac events per 100 patient-years was significantly higher for CA10 than for CA5 [1.7 (1.0 to 2.8) v 0.5 (0.1 to 1.2); P=.02]. The risk of cardiac events in CA5 patients, irrespective of the cardiac RT dose-volume, did not differ significantly from rates of cardiac events predicted for the general female population by the Framingham Heart Study. In CA10 patients, the incidence of cardiac events was significantly increased (relative risk ratio, 3.6; P < .00003) compared with the Framingham population, particularly in groups that also received moderate and high dose-volume cardiac RT. CONCLUSION: Conventional-dose adjuvant doxorubicin as delivered in the CA5 regimen by itself, or in combination with locoregional RT, was not associated with a significant increase in the risk of cardiac events. Higher doses of adjuvant doxorubicin (CA10) were associated with a threefold to fourfold increased risk of cardiac events. This appears to be especially true in patients treated with higher dose-volumes of cardiac RT. Larger studies with longer follow-up periods are needed to confirm these results.     

Primary human prostate cancer cells harboring p53 mutations are clonally expanded in metastases

Recent studies suggest a role for p53 in prostate cancer progression. Although p53 mutations in primary prostate cancer tissues are relatively infrequent, they occur at significant levels in metastatic disease. Here we describe a novel approach to the molecular analysis of p53 in paired specimens of primary and metastatic prostate cancer that results in quantitative estimates of the extent of clonal expansion. In 20 pairs with 1 or both specimens p53 immunopositive and in 6 pairs with both specimens immunonegative, the frequency of mutations was estimated by microdissection of the cancer from fixed and sectioned tissues, isolation of the DNA followed by PCR amplification of p53 genomic fragments, and cloning of the PCR products into plasmid vectors. At least 90 clones/tissue specimen were screened for mutations by single-strand conformational polymorphism analysis. DNA from abnormally migrating single-strand conformational polymorphism samples was sequenced to confirm mutations. Missense mutations in exon 5, 7, or 8 were detected in 9 of 20 immunopositive pairs and in 1 of 6 immunonegative pairs. A marked heterogeneity of mutations in primary prostate cancer was apparent. The frequency of p53 mutations was greater in the metastases than in the primary tumors. In three immunopositive pairs, the same p53 mutation was demonstrated at a low frequency in the primary tumor but was demonstrated at a greater frequency in the metastasis, indicating relatively limited clonal expansion of cells harboring specific p53 mutations in the primary tumor, yet significant clonal growth at metastatic sites as determined by this novel method.     

BAX frameshift mutations in cell lines derived from human haemopoietic malignancies are associated with resistance to apoptosis and microsatellite instability

Bax suppresses tumorigenesis in a mouse model system and Bax-deficient mice exhibit lymphoid hyperplasia suggesting that BAX functions as a tumour suppressor in human haemopoietic cells. We examined BAX expression in 20 cell lines derived from human haemopoietic malignancies and consistent with a potential tumour suppressor function, identified two cell lines, DG75 (a Burkitt lymphoma cell line) and Jurkat (a T-cell leukaemia line), which lacked detectable BAX expression. Apoptosis of DG75 cells induced by low serum or ionomycin was significantly delayed relative to similar Burkitt lymphoma cell lines with normal BAX levels. Although DG75 and Jurkat cells expressed several BAX RNA species including the prototypical BAX alpha RNA, the absence of BAX protein was due to single base deletions and additions in a polyguanine tract within the BAX open reading frame. These frameshift mutations result in premature termination of translation and have recently also been identified in some colon cancers with microsatellite instability. Although mismatch repair defects are not considered a common feature of haemopoietic malignancies, DG75 and Jurkat cells had widespread microsatellite instability and did not express detectable levels of MSH2. In Jurkat cells, lack of MSH2 expression was due to a point mutation in exon 13 of MSH2 resulting in premature termination of translation. Our results suggest that a pathway linking mismatch repair defects, BAX tumour suppressor frameshift mutations and resistance to apoptosis may be a key feature of some lymphomas and leukaemias.     

Specific K-ras2 mutations in human sporadic colorectal adenomas are associated with DNA near-diploid aneuploidy and inhibition of proliferation

Recent studies indicate that p21ras proteins mediate their multiple cell functions through interactions with multiple effectors and that the number of new effectors is growing. We recently reported that K-ras2 mutations in human colorectal adenomas were associated with chromosome instability and proliferation changes. In the present study, we extend these previous observations. Hereditary and multiple (n > or = 5) adenomas and adenomas with early cancer were excluded. Dysplasia was moderate in 91 cases and high in 25, and the median adenoma size was 1.5 cm. K-ras2 spectrum analysis was done by sequence-specific oligonucleotide hybridization using nuclear suspensions provided by analysis and sorting of multiparameter flow cytometry. In particular, tissue inflammatory cells were separated for DNA diploid tumors, whereas DNA aneuploid epithelial subclones were analyzed separately. K-ras2 mutations and DNA aneuploidy were both detected in 29 of 116 (25%) cases. DNA aneuploid index was in the near-diploid region in the majority of cases. DNA aneuploidy was strongly associated with G-->C/T transversions. An association was also found between low S-phase values and G-->A transitions. These findings were confirmed using multivariate logistic regression analysis to account for the effects of size, dysplasia, site, type, age, and sex. These data suggest that specific K-ras2 mutations in a subgroup of human sporadic colorectal adenomas play a role in chromosome instability and, contrary to expectations, are associated with inhibition of proliferation.