p53 alteration correlates with negative ER, negative PgR, and high histologic grade in breast cancer

p53 and Breast Cancer

Inactivation of the p53 tumor suppressor gene is one of the commonest genetic changes identified in human breast cancer. In this review, the structure and function of the p53 gene and its protein products will be discussed, with particular reference to p53 alterations that contribute to carcinogenesis. The frequency and pattern of p53 alterations in breast cancer will be outlined, laboratory methods for their detection briefly summarized, and the potential use of p53 as a prognostic and predictive marker discussed.

Household income is associated with the p53 mutation frequency in human breast tumors

BACKGROUND

A study from Scotland reported that the p53 mutation frequency in breast tumors is associated with socio-economic deprivation.

METHODS

We analyzed the association of the tumor p53 mutational status with tumor characteristics, education, and self-reported annual household income (HI) among 173 breast cancer patients from the greater Baltimore area, United States.

RESULTS

p53 mutational frequency was significantly associated with HI. Patients with < $15,000 HI had the highest p53 mutation frequency (21%), followed by the income group between $15,000 and $60,000 (18%), while those above $60,000 HI had the fewest mutations (5%). When dichotomized at $60,000, 26 out of 135 patients in the low income category had acquired a p53 mutation, while only 2 out of 38 with a high income carried a mutation (P < 0.05). In the adjusted logistic regression analysis with 3 income categories (trend test), the association between HI and p53 mutational status was independent of tumor characteristics, age, race/ethnicity, tobacco smoking and body mass. Further analyses revealed that HI may impact the p53 mutational frequency preferentially in patients who develop an estrogen receptor (ER)-negative disease. Within this group, 42% of the low income patients (< $15,000 HI) carried a mutation, followed by the middle income group (21%), while those above $60,000 HI did not carry mutations (Ptrend < 0.05).

CONCLUSIONS

HI is associated with the p53 mutational frequency in patients who develop an ER-negative disease. Furthermore, high income patients may acquire fewer p53 mutations than other patients, suggesting that lifetime exposures associated with socio-economic status may impact breast cancer biology.

p53, a target of estrogen receptor (ER) α, modulates DNA damage-induced growth suppression in ER-positive breast cancer cells

In response to genotoxic stress, the p53 tumor suppressor induces target genes for cell cycle arrest, apoptosis, and DNA repair. Although p53 is the most commonly mutated gene in all human cancers, it is only mutated in about 20% of breast cancers. 70% of all breast cancer cases are estrogen receptor (ER)-positive and express ERα. ER-positive breast cancer generally indicates good patient prognosis and treatment responsiveness with antiestrogens, such as tamoxifen. However, ER-positive breast cancer patients can experience loss or a reduction in ERα, which is associated with aggressive tumor growth, increased invasiveness, poor prognosis, and loss of p53 function. Consistent with this, we found that p53 is a target gene of ERα. Specifically, we found that knockdown of ERα decreases expression of p53 and its downstream targets, MDM2 and p21. In addition, we found that ERα activates p53 transcription via binding to estrogen response element half-sites within the p53 promoter. Moreover, we found that loss of ERα desensitizes, whereas ectopic expression of ERα sensitizes, breast cancer cells to DNA damage-induced growth suppression in a p53-dependent manner. Altogether, this study provides an insight into a feedback loop between ERα and p53 and a biological role of p53 in the DNA damage response in ER-positive breast cancers.

Impact of germline BRCA1 mutations and overexpression of p53 on prognosis and response to treatment following breast carcinoma: 10-year follow up data

BACKGROUND

Overexpression of p53 has been associated with poor survival following breast carcinoma. BRCA1 interacts biochemically with p53 and may also contribute to poor outcome when constitutionally mutated. The joint effect of both abnormalities has not been studied. The primary objective of this study was to assess the impact of germline BRCA1 mutations and p53 overexpression on survival after 10 years of follow-up.

METHODS

A historical cohort of Ashkenazi Jewish women 65 years or younger with invasive breast carcinoma was tested for BRCA1 founder mutations. p53 overexpression was assessed by immunohistochemistry. Clinicopathologic information was obtained by chart review.

RESULTS

In total, 278 women were analyzed. On univariate analysis, p53 overexpression (n = 63) was prognostic for worse overall survival (relative risk [RR] 2.6, P = 0.001) whereas BRCA1 germline mutations (n = 30) were of borderline significance (RR 1.9, P = 0.052). In the lymph node-negative subpopulation, BRCA1 mutation status conferred a higher mortality on univariate (RR 5.6, P < 0.001) and multivariate (RR 3.5, P = 0.03) analyses. There was a trend in favor of a worse prognosis for women who carried a germline BRCA1 mutation and whose tumor overexpressed p53. When compared with noncarriers, BRCA1 mutation carriers had a worse overall survival if they did not receive adjuvant chemotherapy (RR 3.3, P= 0.01) or adjuvant hormonal therapy (RR 2.3, P = 0.02).

CONCLUSIONS

Germline BRCA1 mutations and p53 overexpression carry a negative prognosis that is not additive to known prognostic factors. Given the experimental sensitivity of BRCA1-mutated cells to chemotherapy, the worse survival among BRCA1 mutation-carrying lymph node-negative breast carcinoma patients may be partly explained by the significantly lower proportion of lymph node-negative patients who received adjuvant chemotherapy (P < 0.001).

P53 protein accumulation in non-invasive lesions surrounding p53 mutation positive invasive breast cancers

p53 mutation is a common event in sporadic breast cancer being found in 15-50% of invasive carcinomas. The purpose of this study was to determine the earliest histologic stage at which p53 mutation could be detected with a widely used anti-p53 antibody (DO7, Novocastra) which recognizes both wild type and mutant forms. p53 expression was assessed immunohistochemically in 12 primary breast carcinomas with known p53 mutations and in all pre-malignant epithelial lesions surrounding these invasive cancers. Strong p53 nuclear staining was found in all of the tumors known to have missense mutations and none of the tumors with truncation mutations. In cases with intense staining in the invasive carcinoma, a similar quality of staining was also seen in all areas of DCIS (ductal carcinoma in situ) and was representative of missense p53 mutations. Lighter nuclear staining intensity was observed in up to 40% of cells in areas of hyperplasia and in up to 30% of normal breast lobules irrespective of the type of mutation found in the invasive carcinoma. This weak staining was not specific to mutated p53 and may indicate increased amounts of normal p53 protein. We conclude that p53 inactivation occurs prior to invasion in breast carcinogenesis, with mutations being uniformly identified in DCIS associated with p53-mutated invasive carcinomas. In contrast, there is no evidence that epithelial hyperplasia or epithelial cells of the terminal duct lobular unit harbor the same mutations as their associated invasive carcinoma.

P53 determination alongside classical prognostic factors in node-negative breast cancer: an evaluation at more than 10-year follow-up

BACKGROUND

There is heterogeneity of methods and conflicting results concerning the prognostic value of p53 in node-negative breast cancer. The clinical value of a quantitative method for measuring tumoralp53 content still needs to be evaluated.

PATIENTS AND METHODS

A long-term retrospective study was conducted on 297 node-negative patients with a median follow-up greater than 10 years (11 years, 101-172 months). Classic prognostic factors were considered including age, tumor size, histoprognostic grade and estradiol (ER) and progesterone receptors (PR). In addition, the value of p53 determination (immunoluminometric assay in tumor cytosol) was assessed for this long follow-up period.

RESULTS

p53 concentrations were significantly linked to the histological grade (P = 0.001), to tumor size (P = 0.02) and ER status (P = 0.01). Higher p53 tumoral concentrations were found in tumors with large size, pejorative histological grade and negative ER status. In contrast, p53 tumoral concentrations were not influenced by menopausal or PR status. Multivariate Cox analysis demonstrates that tumor size was the only significant predictor of disease-free survival (P = 0.049) with a risk factor at 1.38. As regards specific survival, univariate Cox analysis indicates that p53 taken as a continuous variable is a significant predictor (P = 0.024) together with histological grade, tumor size and ER status. In a multivariate Cox analysis there were two significant and independent variables for predicting overall survival: tumor size (P = 0.031) and, ER status (P = 0.015) with the highest risk factor (RR = 2.14).

CONCLUSIONS

The present investigation points out that the prognostic power of p53 tumor determination evaluated at more than 10 years median survival is not higher than the well-recognized classic prognostic factors in node-negative breast cancer. The present data highlight the need to assess the prognostic value of potentially new biological factors in node-negative breast cancer on cohorts of patients followed over periods in excess of 10 years.

AN OVERVIEW OF PROGNOSTIC MARKERS IN BREAST CANCER

For many years axillary lymph nodes metastasis was the most important prognostic factor to predict the overall and disease free survival and guided the oncologists for institution of chemotherapy in breast cancer cases. However this factor alone or in combination with other parameters like, age of the patient, tumour size, histological type and tumour grade failed to predict the prognosis accurately in number of these cases. In pursuit to achieve the perfection, many new parameters which are biological or molecular in nature have been discovered. It is claimed that these factors not only have the capability to predict the prognosis but are also able to identify 'high risk' group of patients. However analysing all these parameters in a given case is not only cost prohibitive but also not essential. In order to solve this problem few important biological parameters have been reviewed, which are considered to cover all the important facets of the breast cancer. The parameters reviewed are ER, PR, S phase fraction, DNA ploidy, MIB-1 antibody, p53, C-erb-2, nm23, Cathepsin, Topoisomerase II alpha.

Prognostic Factors for Node-negative Breast Cancers: Results of a Study Program by the Japanese Breast Cancer Society

BACKGROUND: Prognostic factors for predicting the recurrence of node-negativebreast cancers have been controversial. The present study was performed to elucidate practically useful prognostic factors using formalin-fixed paraffin sections. METHODS: This was a case-controlled multi-institutional study that composed 40 patients with recurrent node-negative breast cancer and 80 patients with node-negative breast cancer but without recurrence after radical surgery. Tumors weresmaller than 3 cm in diameter and were treated surgically between January 1, 1985 and December 31, 1990. The recurrent and non-recurrent cases were matched with regard to their age, adjuvant chemotherapy and the year in which surgery was performed. Fourteen immunohistochemical factors and 8 histological factors of theprimary tumor were studied on formalin-fixed, paraffin-embedded sections by immunohistochemical and histochemical analyses. RESULTS: According to univariate analysis, factors such as progesterone receptor (PgR), MIB-1, CD44v6, CD44v9 and platelet-derived endothelial cell growth factor (PDECGF) were significantly different between the recurrent and non-recurrent groups (p &ly; 0.1; Wilcoxon-Mann-Whitney analysis). Chi-squared test showed significant differences in MIB-1, cdc2 and stromal plasminogen activator receptor (suPAR). Histologically, mitotic count was also significantly different between the two groups (p < 0.005). Multivariate analysis revealed that positivity for cdc2 (p=0.01), high mitotic count (p=0.04) and negativity for CD44v9 (p=0.02)were independent prognostic factors among variables selected by univariate analysis, and that positivity for MIB-1 (p=0.03) and cdc2 (p =0.01), and negativity for CD44v9 (p =0.03) were independent prognostic factors among the immunohistochemical markers examined. CONCLUSION: Our results indicated that positivity for MIB-1 and cdc2, high mitotic count and negativity for CD44v9 could serve as independent factors for predicting the recurrence of node-negative breast cancer.