The p53 tumor suppressor gene in breast cancer

Summary Alterations of the p53 tumor suppressor gene are the most common genetic changes found so far in breast cancer, suggesting that the gene plays a central role in the development of the disease. p53 functions as a negative regulator of cell growth, and alterations in the gene lead to loss of this negative growth regulation and more rapid cell proliferation. A number of independent groups using different methods of detection have shown that p53 alterations are associated with more aggressive tumor biologic factors and a poorer prognosis in breast cancer patients. Because of its possible role in the regulation of apoptosis and response to DNA damage, p53 status could also be a predictive marker for response to hormonal or chemotherapy.     

他莫昔芬治疗芳香化酶抑制剂耐药的激素受体阳性绝经后转移性乳腺癌患者的临床研究

目的:探讨他莫昔芬治疗芳香化酶抑制剂（AIs）耐药的激素受体阳性（HR+）绝经后转移性乳腺癌（MBC）患者的疗效和安全性。方法:回顾性分析他莫昔芬治疗AIs耐药的30例HR+绝经后MBC患者的临床资料,观察终点为缓解率（RR）、临床获益率（CBR）、疾病进展时间（TTP）和安全性。结果:30例患者中,CR 1例,PR 9例,SD 15例,RR为33.3%,CBR 为50%,中位TTP 6.1个月。23例骨和/或软组织转移患者中,RR为34.8%,CBR为52.2%,中位TTP 7.3个月;7例肝脏和/或肺部转移患者中,RR为28.6%,CBR为42.8%,中位TTP 4.8个月（P=0.019）。不良反应多为面部潮红、阴道干燥、白带增多、阴道出血、恶心、呕吐、腹泻等,均为I、II级。结论:他莫昔芬治疗AIs耐药的HR+绝经后MBC患者安全有效,可改善患者预后。     

A case of advanced breast cancer successfully treated with primary endocrine therapy

We present a case of a premenopausal woman with advanced hormone-sensitive breast cancer who was successfully treated with primary endocrine therapy consisting of ovarian ablation followed by a combined endocrine regimen of the aromatase inhibitor fadrozole 2 mg daily and tamoxifen 20 mg daily. During the 5 months treatment period, PR evaluation of the loco-regional lesions was performed The patient then underwent mastectomy with axillary lymph node dissection followed by fadrozole and tamoxifen therapy. Throughout the treatment course, no adverse events were encountered and the patient has been enjoying a favorable quality of life. As shown by this case, primary endocrine therapy is a promising treatment option for hormonesensitive breast cancer. However, this modality should be continued to be regarded as experimental.     

Prospective characterization of musculoskeletal symptoms in early stage breast cancer patients treated with aromatase inhibitors

Purpose Aromatase inhibitors (AIs) are increasingly used as adjuvant treatment of postmenopausal women with hormone receptor-positive breast cancer. AIs are commonly associated with musculoskeletal symptoms. The primary objective of this study was to describe the musculoskeletal symptoms that developed in the first 100 subjects enrolled who had at least 6 months follow-up. Methods Women with early stage hormone receptor-positive breast cancer were recruited into a multicenter randomized clinical trial to study the pharmacogenomics of two AIs, exemestane, and letrozole. Patients completed the Health Assessment Questionnaire (HAQ) and Visual Analog Scale (VAS) at baseline, 1, 3, 6, and 12 months to assess changes in function and pain, respectively. Patients were referred for evaluation by a rheumatologist if their HAQ and/or VAS scores exceeded a predefined threshold. Results Forty-four of 97 eligible patients (45.4%) met criteria for rheumatologic referral. Three patients were ineligible because of elevated baseline HAQ (2) and failure to initiate AI therapy (1). No baseline characteristics were significantly associated with referral. Median time to onset of symptoms was 1.6 months (range 0.4-10 months). Clinical and laboratory evaluation of patients evaluated by rheumatology suggested that the majority developed either non-inflammatory musculoskeletal symptoms or inflammation localized to tenosynovial structures. Thirteen patients discontinued AI therapy because of musculoskeletal toxicity after a median 6.1 months (range 2.2-13 months). Conclusions Musculoskeletal side effects were common in AI-treated patients, resulting in therapy discontinuation in more than 10% of patients. There are no identifiable pre-therapy indicators of risk, and the etiology remains elusive.     

Ethinylestradiol is beneficial for postmenopausal patients with heavily pre-treated metastatic breast cancer after prior aromatase inhibitor treatment: a prospective study

Background:

Oestrogens usually stimulate the progression of oestrogen receptor (ER)-positive breast cancer. Paradoxically, high-dose oestrogens suppress the growth of these tumours in certain circumstances.

Methods:

We prospectively examined the efficacy and safety of ethinylestradiol treatment (3 mg per day oral) in postmenopausal patients with advanced or recurrent ER-positive breast cancer who had previously received endocrine therapies, especially those with resistance to aromatase inhibitors.

Results:

Eighteen patients were enrolled with the median age of 63 years and the mean observation time of 9.2 months. Three cases withdrew within 1 week due to oestrogen flare reactions with nausea, fatigue and muscle-skeletal pain. The response rate was 50% (9 out of 18), and the clinical benefit rate was 56% (10 out of 18). The stable disease (<6 months) was 17% (3 out of 18) and another 2 cases were judged as progressive disease. Time-to-treatment failure including 2 on treatment was a median of 5.6 months (range 0.1 to 14.5⁺). Although vaginal bleeding or endometrial thickening was observed in patients receiving long-term treatment, there were no severe adverse events, such as deep venous thrombosis or other malignancies.

Conclusion:

Although the mechanism of this treatment has not been fully understood, our data may contribute to change the common view of late-stage endocrine therapy.     

p53突变型乳腺癌中Ki67表达水平的临床意义

目的：探讨乳腺癌组织中p53的突变情况及Ki67的表达水平,明确p53与Ki67联合作用在乳腺癌临床病理因素上的体现。方法：应用免疫组化SP法检测165例乳腺癌组织中p53、Ki67的表达,分析其与临床病理因素之间的关系。结果：p53的突变率为55.8%（92/165）,Ki67的阳性表达率为69.1% （114/165）。p53的突变情况与患者年龄、肿块大小、淋巴结转移、TNM分期、ER和PR的表达水平无关,但与HER-2的表达水平呈正相关。在总人群中Ki67的表达水平与肿块大小和淋巴结转移无关。亚组分析显示在p53突变的患者中,Ki67的表达水平与肿块的大小呈正相关（r=0.311,P=0.003）,与淋巴结转移呈正相关（r=0.342,P=0.001）。结论：在p53突变型乳腺癌中Ki67的表达与T分期及N分期均呈正相关,在p53突变人群中Ki67对乳腺癌的生物学行为和患者的预后可能有更高的预测价值,二者联合检测与解读可能更有助于判断乳腺癌患者的预后。     

The p53 positive Bcl-2 negative phenotype is an independent marker of prognosis in breast cancer

The purpose of this work was to determine if the immunohistochemical p53 (+) Bcl-2 (-) phenotype predicts survival in breast cancer patients. Tissue from 819 cases of resected primary breast cancer, presented between 1986 and 1998, were assembled in tissue microarray format. Clinicopathological data and prospective disease specific survival data were collected prospectively and immunohistochemical analyses of p53 and Bcl-2 expression were performed using antibodies DO-7 (p53) and 124 (Bcl-2) employing a standard IHC protocol. The expression data were correlated with clinicopathological variables and outcomes in both univariate (chi(2)) and multivariate (Cox's regression) analyses. Abnormal p53 expression and positive Bcl-2 expression were detected in 29% (193/673) and 46% (307/673) of tumours, respectively. On univariate analysis Bcl-2 expression was correlated with the clinicopathological features of less aggressive disease and loss of Bcl-2 expression correlated with a reduction in survival (log rank = 11.91; p < 0.001). p53 expression correlated with the clinicopathological features of aggressive cancers and a reduction in survival (log rank = 17.81; p < 0.001). Nineteen percent (127/673) of tumours displayed a p53 (+) Bcl-2 (-) phenotype. Kaplan-Meier analysis revealed a significant reduction in survival in these cases (log rank 34.01; p < 0.001). Multivariate analysis showed that while neither p53 expression nor Bcl-2 expression alone had independent prognostic significance, the p53 (+) Bcl-2 (-) phenotype remained independently associated with a worse prognosis (HR 1.79 95%CI 1.10-2.89 p = 0.018).     

Obesity at diagnosis is associated with inferior outcomes in hormone receptor‐positive operable breast cancer

BACKGROUND:

Obesity has been associated with inferior outcomes in operable breast cancer, but the relation between body mass index (BMI) and outcomes by breast cancer subtype has not been previously evaluated.

METHODS:

The authors evaluated the relation between BMI and outcomes in 3 adjuvant trials coordinated by the Eastern Cooperative Oncology Group that included chemotherapy regimens with doxorubicin and cyclophosphamide, including E1199, E5188, and E3189. Results are expressed as hazard ratios (HRs) from Cox proportional hazards models (HR >1 indicates a worse outcome). All P values are 2‐sided.

RESULTS:

When evaluated as a continuous variable in trial E1199, increasing BMI within the obese (BMI, ≥30 kg/m²) and overweight (BMI, 25‐29.9 kg/m²) ranges was associated with inferior outcomes in hormone receptor‐positive, human epidermal growth receptor 2 (HER‐2)/neu‐negative disease for disease‐free survival (DFS; P = .0006) and overall survival (OS; P = .0007), but not in HER‐2/neu–overexpressing or triple‐negative disease. When evaluated as a categorical variable, obesity was associated with inferior DFS (HR, 1.24; 95% confidence interval [CI], 1.06‐1.46; P = .0008) and OS (HR, 1.37; 95% CI, 1.13‐1.67; P = .002) in hormone receptor‐positive disease, but not other subtypes. In a model including obesity, disease subtype, and their interaction, the interaction term was significant for OS (P = .02) and showed a strong trend for DFS (P = .07). Similar results were found in 2 other trials (E5188, E3189).

CONCLUSIONS:

In a clinical trial population that excluded patients with significant comorbidities, obesity was associated with inferior outcomes specifically in patients with hormone receptor‐positive operable breast cancer treated with standard chemohormonal therapy. Cancer 2012. © 2012 American Cancer Society.     

MIEAP,a p53-downstream gene,is associated with suppression of breast cancer cell proliferation and better survival

Mitochondria-eating protein (MIEAP; also known as SPATA18), a p53-downstream gene, is involved in mitochondrial quality control (MQC). Enforced MIEAP expression induces caspase-dependent cell death in vitro, and impairment of the p53/MIEAP-regulated MQC pathway is frequently observed in breast cancer (BC), resulting in poor disease-free survival (DFS). To investigate the clinical significance of MIEAP in BC, we identified 2,980 patients from two global, large-scale primary BC cohorts: the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC; n=1,904) and the Cancer Genome Atlas (TCGA; n=1,076). We divided patients in each cohort into high and low groups based on median gene expression levels and analyzed the association between MIEAP expression and clinical outcomes. Compared with normal tumors, MIEAP expression was significantly downregulated in all patients with p53-mutant BC regardless of subtype. MIEAP expression was negatively correlated with KI67 expression. Gene set enrichment analysis demonstrated that cell cycle- and proliferation-associated gene sets were significantly enriched in MIEAP-low tumors compared to MIEAP-high tumors. Patients with MIEAP-high luminal subtype were associated with significantly longer DFS than those with MIEAP-low luminal tumors in both cohorts, whereas significantly longer overall survival was observed only in the METABRIC cohort, which has roughly double the number of samples. These results indicated that the mechanistic role of MIEAP is clinically relevant in the two independent cohorts. This is the first study to use large cohorts to demonstrate the association between MIEAP expression and survival in patients with luminal subtype BC.     

Therapeutic potential of recombinant p53 overexpression in breast cancer cells expressing endogenous wild-type p53

Reconstitution of the p53-dependent apoptotic pathway by gene transfer of a recombinant wild-type p53 minigene leads to rapid apoptotic cell death in breast and other cancer cell types expressing null or mutant p53. Tumour cells expressing wild-type p53 have been reported to be more resistant to this treatment strategy, presumably as a result of mutations in downstream regulators of p53-dependent apoptotic signalling. The MCF-7 breast cancer cell line is representative of this class of tumour cell. Our recent observation of a p53-dependent apoptotic response following adenovirus-mediated HSV thymidine kinase gene transfer and gancyclovir treatment led us to reexamine recombinant p53 cytotoxicity in MCF-7 cells. Infection with a recombinant adenovirus expressing wild-type p53 resulted in a dramatic increase in p53 protein levels and was accompanied by an increase in p21^{WAF 1/CIP1} protein levels and G1 arrest within 24 hours post-infection. A significant decrease in MCF-7 cell viability was first observed at 5 days post-infection and coincided with the appearance of morphological and biochemical changes consistent with apoptotic cell death. By day 7 post-treatment, cell viability decreased to 45% and clonogenic survival was reduced to 12% of controls. The results demonstrate that persistent, high level expression of recombinant p53 can induce programmed cell death in MCF-7 cells. While the mechanism by which p53 overexpression overcomes the defect in downstream apoptotic signalling is not clear, our data suggests that this treatment strategy may be beneficial for the class of tumour cells represented by the MCF-7 cell line.     

Loss of B‐cell translocation gene 2 expression in estrogen receptor‐positive breast cancer predicts tamoxifen resistance

B‐cell translocation gene 2 (BTG2), a gene suppressed in a subset of aggressive breast cancer, is repressed by estrogen. BTG2 inhibits the expression of HER ligands and promotes AKT activation, which plays an essential role in the tamoxifen resistance of estrogen receptor (ER)‐positive breast cancer. To determine if BTG2 expression modifies tamoxifen efficacy, a cohort of 60 patients treated with adjuvant tamoxifen monotherapy was analyzed. We found that increased BTG2 expression showed better clinical survival and was the only independent prognostic factor for disease‐free survival (hazard ratio, 0.691; 95% confidence interval, 0.495–0.963; P = 0.029). Tamoxifen suppressed the human epidermal growth factor receptor 2 (HER2)‐Akt signaling in BTG2 expressing ER‐positive breast cancer cells with a correlated increase in sensitivity, whereas BTG2 knockdown abrogated this sensitivity. Consistent with this observation, tamoxifen significantly suppressed the growth ratio, tumor weight and Ki‐67 expression in BTG2 expressing breast cancer xenografts in mice. These studies demonstrate that BTG2 is a significant factor in tamoxifen response, acting through modification of AKT activation in ER‐positive/HER2‐negative breast cancer.     

p170和p53在乳腺癌组织的表达及临床意义

目的：探讨乳腺癌组织中p170和053的表达及两者之间的关系和临床意义。方法：采用S—P免疫组化法检测96例乳腺癌石蜡标本中p170和053蛋白的表达，分析其与临床病理因素的关系及两者的相关性。结果：96例乳腺癌组织中p170阳性表达率为65．25％（54／96），其表达与患者年龄、肿瘤大小、病理分级、ER和PR表达及淋巴结转移无关。053阳性表达率为41．67％（40／96），其表达与病理分级呈正相关、与患者年龄、病理分型、ER和PR表达及淋巴结转移无明显相关，p170与p53的表达成正相关。结论：p170与p53的表达呈正相关，他们是重要的病理指标，对肿瘤化疗药物的选择有指导意义。     

P73 functionally replaces p53 in Adriamycin-treated, p53-deficient breast cancer cells

p53-Related genes, p73 and p63, encode 2 classes of proteins, TA-p73/p63 and DeltaN-p73/p63. TA-p73/p63 demonstrate p53-like properties including gene transactivation and cell death promotion, whereas DeltaN-p73/p63 lack these p53-like functions. Although p53-deficient cancer cells are often less responsive to chemotherapy, they are not completely drug resistant, suggesting that other apoptotic pathways are at work. Here, we compared for the first time to our knowledge p73 and p63 activation in various breast cancer (BC) cell lines after Adriamycin (ADR) treatment, an agent considered as mandatory in breast cancer chemotherapy. Our study was carried out using 1 p53-proficient BC cell line (MCF7 cells) and 3 BC cell lines deficient in p53 response (MCF7/ADR(IGR), MDA-MB157 and T47D) after ADR-induced genotoxic stress. We report that in cells with no p53 response after ADR treatment, TAp73, but not TAp63 or DeltaN-p73/p63, may replace p53 in triggering not only apoptosis but also cell cycle arrest or DNA repair effectors such as p21, GADD45, 14-3-3sigma and p53R2. We also demonstrate that TAp73 siRNA inhibits the accumulation of TAp73 in response to ADR treatment in MDA-MB157 cells and confers protection against ADR. ADR-induced downregulation of the DeltaNp73 isoform in the T47D cell line with nonfunctional mutant p53 further supports anti-apoptotic function of the isoform antagonistic to both p53 and TA-p73/p63. Exogenous TAp73 and DeltaNp73 overexpression in p53-response-deficient cell lines further confirms these results. cDNA microarray techniques demonstrated that the cellular response induced by p73 during ADR treatment could involve specific genes.     

p53 Mutations are present in colorectal cancer with cytoplasmic p53 accumulation

Previous studies have shown that nuclear p53 over-expression is an indicator of p53 mutations whereas cytoplasmic p53 accumulation is related to wild-type p53 in several kinds of tumors. Cytoplasmic p53 accumulation has been demonstrated to be an independent prognostic factor in colorectal adenocarcinomas. The purpose was to examine whether mutations occur in cases with p53 accumulated in the cytoplasm and whether there are any differences in the frequency and characteristics of p53 mutations in different staining patterns. In the present study, we identified p53 mutations using PCR single-strand conformation polymorphism (SSCP) and DNA sequencing in 75 primary colorectal adenocarcinomas with different staining patterns (negative, nucleus, cytoplasm, nucleus and cytoplasm). The results show that the frequency and nature of mutations in tumors with cytoplasmic p53 accumulation were similar to those with nuclear p53 expression. However, the tumors with accumulation in both the nucleus and cytoplasm demonstrated a higher mutation rate. We suppose that the role of cytoplasmic p53 accumulation in predicting prognosis in patients with colorectal cancer may be dependent on both mutational and non-mutational mechanisms.     

Patterns and predictors of early recurrence in postmenopausal women with estrogen receptor-positive early breast cancer

Previous studies suggest that disease recurrence peaks at around 2 years in patients with early stage breast cancer (EBC), but provide no data regarding recurrence type. This retrospective analysis aimed to identify early recurrence types and risk factors in estrogen receptor-positive (ER+) EBC patients treated with adjuvant tamoxifen following breast cancer surgery. Postmenopausal women diagnosed with ER+ EBC from 1995 to 2004 were evaluated. Annual hazard ratios (HR) for recurrence at different sites were calculated. Time-dependent Cox regression analysis was used to identify predictors of recurrence within 2.5 years of diagnosis, including factors that were more strongly predictive of early than later recurrence. Of 3,614 patients evaluated, 476 developed recurrence during the 5-year median follow-up. Cumulative recurrence rates at 2.5 years (95% confidence interval) were: overall 6.3% (5.5–7.1), locoregional 1.1% (0.7–1.5), contralateral 0.5% (0.3–0.7), and distant 4.8% (4.0–5.6). The annual HR of overall recurrence peaked at 2 years (4.3% per annum). The majority of this peak represented distant recurrence (3.4% per annum). In Cox regression analysis, tumor size and grade, lymph node involvement, lymphovascular invasion, and symptomatic presentation were significant independent predictors of early recurrence. Age at diagnosis was independently predictive of recurrence within 2.5 years of diagnosis but not later recurrence. This study identified an early recurrence peak at 2 years, most of which were distant recurrences. Implementing an aromatase inhibitor after an initial 2–3 years of tamoxifen fails to address this early peak of distant recurrence and the potential breast cancer-associated mortality.     

Prognostic significance of p53 gene alterations in node-negative breast cancer

Summary Mutations in the p53 gene can play a role in the transformation of normal to malignant cells. Because these mutations are more frequently reported later in the course of transformation, their presence could reflect a greater malignant potential of the tumor and, thus, an increased probability of metastasis and recurrence after local therapy. In a pilot study using single-stranded conformation polymorphism analysis (SSCP), 200 node-negative breast tumors were examined for mutations in the region encompassing exons 5 through 9 of the p53 gene. Exons 5 through 9 were tested because they contain 80–90% of known p53 gene mutations. The tumors ranged in size from 1 to 3 cm. 28 tumors were found to have an abnormal band pattern on both initial and repeat analysis. 4 of these tumors were sequenced; 3 contained a p53 mutation and the 4th had a rare neutral polymorphism. Disease-free survival (DFS) at 5 years for women with tumors having an abnormal SSCP analysis was 57% (± 10%), compared to a 79% (± 3%) DFS for the group with a normal pattern. By the log rank test, this difference was highly significant, p 0.01. The relative risk of recurrence for the group with an abnormal SSCP pattern was 2.2. In a multivariate analysis including ER, PgR, ploidy, S-phase, age, and tumor size, an abnormal p53 by SSCP analysis and patient age were the only factors that independently predicted DFS at 5 years. Conclusion: Women with node-negative breast cancer who have tumors with alterations in the p53 gene, as indicated by SSCP analysis, have a significantly poorer prognosis and a higher rate of relapse at 5 years. The prognostic significance is maintained in a multivariate analysis including many established prognostic factors.We regret to report that Dr. McGuire died March 25, 1992, while this work was in progress.     

Distinct tumor protein p53 mutants in breast cancer subgroups

Tumor protein p53 (TP53) is mutated in approximately 30% of breast cancers, but this frequency fluctuates widely between subclasses. We investigated the p53 mutation status in 572 breast tumors, classified into luminal, basal and molecular apocrine subgroups. As expected, the lowest mutation frequency was observed in luminal (26%), and the highest in basal (88%) tumors. Luminal tumors showed significantly higher frequency of substitutions (82 vs. 65%), notably A/T to G/C transitions (31 vs. 15%), whereas molecular apocrine and basal tumors presented much higher frequencies of complex mutations (deletions/insertions) (36 and 33%, respectively, vs. 18%). Accordingly, missense mutations were significantly more frequent in luminal tumors (75 vs. 54%), whereas basal tumors displayed significantly increased rates of TP53 truncations (43 vs. 25%), resulting in loss of function and/or expression. Interestingly, as basal tumors, molecular apocrine tumors presented with a high rate of complex mutations, but paradoxically, these were not associated with increased frequency of p53 truncation. As in luminal tumors, this could reflect a selective pressure for p53 gain of function, possibly through P63/P73 inactivation. Collectively, these observations point not only to different mechanisms of TP53 alterations, but also to different functional consequences in the different breast cancer subtypes.