p53 protein accumulation predicts resistance to endocrine therapy and decreased post-relapse survival in metastatic breast cancer
© Yamashita et al.; licensee BioMed Central Ltd. 2006
Received: 5 February 2006
Accepted: 25 July 2006
Published: 25 July 2006
Endocrine therapy is the most important treatment option for women with hormone receptor-positive breast cancer. The potential mechanisms for endocrine resistance involve estrogen receptor (ER)-coregulatory proteins and cross-talk between ER and other growth factor-signaling networks. However, the factors and pathways responsible for endocrine resistance are still poorly identified.
Materials and methods
The expression of HER2, p53, and Ki67 was examined by immunohistochemistry in primary breast tumour specimens from 73 metastatic breast cancer patients who received first-line treatment with endocrine therapy on relapse, and analysed to determine whether expression of these molecular markers affected the response to endocrine therapy.
Of the 73 invasive ductal carcinomas, 12.3%, 21.9%, and 35.6% were positive for HER2 overexpression, p53 protein accumulation, and Ki67 expression, respectively. All patients received endocrine therapy as first-line treatment for metastatic breast cancer; 34 patients (46.6%) responded. Patients with primary breast tumours that had p53 protein accumulation and Ki67 expression showed significantly more resistance to endocrine therapy (P = 0.0049 and P = 0.024, respectively). There were also tendencies for HER2 overexpression to correlate with resistance to endocrine therapy, but this did not reach significance. p53 protein accumulation and HER2 overexpression significantly reduced post-relapse survival (P < 0.0001 and P = 0.001, respectively), and these factors were also statistically significant in a multivariate analysis.
These data suggest that p53 protein accumulation is helpful in selecting patients who may benefit from endocrine therapy and is a prognostic marker in hormone receptor-positive metastatic breast cancer.
Endocrine therapy has become the most important treatment option for women with estrogen receptor (ER)-positive breast cancer. Nevertheless, many breast cancer patients with tumours expressing high levels of ER are unresponsive to endocrine therapy, and all patients with advanced disease eventually develop resistance to the therapy. The potential mechanisms behind either intrinsic or acquired endocrine resistance involve ER-coregulatory proteins and cross-talk between the ER pathway and other growth factor-signaling networks [1, 2]. An understanding of the molecular mechanisms that modulate the activity of the estrogen-signaling network has enabled new ways of overcoming endocrine resistance to be developed.
Several specific proteins have been suggested to contribute to endocrine therapy resistance. HER2 overexpression might be associated with reduced efficacy of adjuvant endocrine therapy with tamoxifen [3–5]. De Laurentiis and colleagues recently conducted a meta-analysis and found that HER2-positive metastatic breast cancer was less responsive to any type of endocrine therapy .
Nearly one third of breast tumours have mutations in the p53 gene, which are associated with high histological grade and rapid progression . Immunohistochemical assays generally detect nuclear accumulation of the protein, which is often related to conformational alterations and a prolonged half-life of the encoded protein [8, 9]. Mutation of the p53 gene or overexpression of its protein product has been identified in 14% to 52% of primary breast tumour specimens, and these alterations were found to be associated with poor prognosis in an analysis of more than 3,000 patients with primary breast cancer . We recently analysed the expression of HER2, p53, and Ki67 in 506 invasive ductal carcinoma tissues and showed that the coexistence of HER2 overexpression and p53 protein accumulation was a strong prognostic molecular marker in breast cancer .
Apoptosis may represent a common mechanism whereby a variety of antitumour treatments results in cell death. Cells with loss of p53 gene function may be unable to undergo apoptosis and thus be resistant to these forms of therapy . Because mutated protein might accumulate in cells, immunohistochemical staining has been a popular surrogate marker for p53 mutational status. Studies have been published that examined the predictive value of p53 alterations at the gene level, or p53 expression status by immunohistochemistry (IHC), for response to chemotherapy. Many of these studies reported that p53 alterations predict resistance to anthracyclins [13–19]; cyclophosphamide, methotrexate, and fluorouracil (CMF); or other agents [20–22]. However, of the few studies that have examined the association between p53 status and response to endocrine therapy [23–27], one study  reported a value for p53 in predicting endocrine resistance.
We previously described that expression of ER-α and progesterone receptor (PR) by IHC in primary breast tumours is predictive of response to endocrine therapy in patients with metastatic breast cancer who received endocrine therapy on relapse . In this study, we examined the expression of HER2, p53, and Ki67 by IHC in primary breast tumour specimens from 73 patients with metastatic breast cancer who received first-line treatment with endocrine therapy on relapse, and analysed whether expression of these molecular markers affected the response to endocrine therapy.
Materials and methods
Patients and breast cancer tissues
Clinicopathological characteristics of patients, primary breast tumours, and treatment
Number of patients (percentage)
Total number of patients
Age at diagnosis (years)
29 to 77
Tumour size (cm)
Number of positive lymph nodes
Disease-free interval (months)
Mean ± SD
39.8 ± 25.7
2 to 123
First-line endocrine therapy for metastatic breast cancer
LHRH agonist + tamoxifen
First-line endocrine therapy for metastatic breast cancer and response criteria
When the patients relapsed and were diagnosed with metastatic breast cancer, they started endocrine therapy (Table 1). Patients were assessed monthly for clinical response, which was defined according to World Health Organization criteria as complete response, partial response, no change, and progressive disease. The presence of progressive disease indicated treatment failure; all other clinical responses were considered to show efficacy of treatment. Stable disease was included as a response to treatment because patients with stable disease clearly benefited clinically in metastatic breast cancer.
Immunohistochemical analysis for ER-α, PR, HER2, p53, and Ki67
One 4-μm section of each submitted paraffin block was first stained with hematoxylin and eosin to verify that an adequate number of invasive ductal carcinoma cells were present, and the fixation quality was sufficient for immunohistochemical analysis as described previously [11, 28]. Serial sections (4-μm) were prepared from selected blocks and float-mounted on adhesive-coated glass slides for ER-α, PR, HER2, p53, or Ki67 staining. Primary antibodies included monoclonal mouse anti-human ER antibody (1D5; Dako Denmark A/S, Glostrup, Denmark) at 1:100 dilution for ER-α, monoclonal mouse anti-human PgR antibody (636; Dako Denmark A/S) at 1:100 dilution for PR, rabbit anti-human c-erbB-2 oncoprotein antibody (Dako Denmark A/S) at 1:200 dilution for HER2, monoclonal mouse anti-human p53 protein antibody (PAb1801; Novocastra, Newcastle, UK) at 1:50 dilution for p53, and monoclonal mouse anti-human Ki67 antibody (MIB-1; Dako Denmark A/S) at 1:100 dilution for Ki67. The Dako Denmark A/S EnVision system (Dako Denmark A/S EnVision labeled polymer, peroxidase) was used as the detection system for ER-α, PR, HER2, and Ki67. The streptavidin-biotin system (SAB-PO kit; Nichirei Co., Inc., Tokyo, Japan) was used for detection of the bound antibody of p53.
Immunostained slides were scored after the entire slide was evaluated by light microscopy. The expression of ER-α and PR was scored by assigning proportion and intensity scores, in accordance with the procedure of Allred and colleagues . Any brown nuclear staining in invasive breast epithelium was counted toward the proportion score. Tumours with a score of 3 or greater were considered to be positive for ER-α and PR expression. HER2 immunostaining was evaluated by the same method as the HercepTest (Dako Denmark A/S). To determine the score of HER2 expression, the membrane staining pattern was estimated and scored on a scale of 0 to 3. Tumours with a score of 3 were considered to be positive for HER2 overexpression. The expression status of p53 and Ki67 was assessed according to the estimated proportion of nuclear staining of tumour cells that were positively stained as described previously . Scoring criteria were as follows: for p53, score of 0 = none; score of 1, <1/10; score of 2, 1/10 to 1/2; and score of 3, >1/2; for Ki67, score of 0 = none; score of 1, <1/100; score of 2, 1/100 to 1/10; score of 3, 1/10 to 1/2; and score of 4, >1/2. Tumours with a score of 2 or greater for p53 were considered to be positive for p53 protein accumulation, and tumours with a score of 3 or greater for Ki67 were considered to be positive for Ki67 expression.
The χ2 test was used to compare the immunohistochemical results of molecular markers with clinicopathological characteristics and response to endocrine therapy. Estimation of post-relapse survival was performed using the Kaplan-Meier method, and differences between survival curves were assessed with the log-rank test. Cox's proportional hazards model was used for univariate and multivariate analyses of prognostic values.
Correlation between HER2, p53, and Ki67 expression and clinicopathological factors
Correlation between clinicopathological factors and molecular markers
Tumour size (cm)
Number of positive lymph nodes
p53 protein accumulation and Ki67 expression in primary breast tumours are predictive of endocrine therapy resistance in metastatic breast cancer
Correlation between immunohistochemical status of HER2, p53, and Ki67 and response to endocrine therapy
Response to endocrine therapy (n = 73)
Patients with HER2 overexpression and p53 protein accumulation in primary breast tumours had a significantly shorter survival after relapse
Prognostic factors in 73 invasive ductal carcinomas compared with post-relapse survival
Lymph node status
The present study indicates that p53 protein accumulation predicts resistance to endocrine therapy and decreased post-relapse survival in patients with metastatic breast cancer who received first-line treatment with endocrine therapy on relapse.
Experimental data suggest a complex cross-talk between HER2 and ER, and it has been hypothesised that HER2-positive tumours may be less responsive to certain endocrine treatments. However, it has yet to be established whether HER2 overexpression is predictive of resistance to endocrine therapy, whether used as an adjuvant therapy after excision of localised breast cancer or as treatment for metastatic disease. In the metastatic setting, several groups have identified a correlation between HER2 overexpression and a lower response rate to endocrine therapy, whereas others have not. De Laurentiis and colleagues recently conducted a meta-analysis of the published studies to obtain an overall pooled estimate of the association between HER2 overexpression and treatment failure rate . They found that HER2-positive metastatic breast cancer was less responsive to any type of endocrine therapy. Our data failed to show an association between HER2 overexpression and resistance to endocrine therapy, possibly due to the small number of patients in our study. Nevertheless, HER2 overexpression significantly reduced post-relapse survival.
It has been reported from three groups of clinical trials that p53 status by IHC does not predict response to tamoxifen [23–25]. Elledge et al. found that p53 expression as measured by IHC was not associated with response to tamoxifen in 205 patients with metastatic breast cancer, although patients with higher p53 had a worse survival . It has also been reported not to predict tamoxifen resistance in ER-positive, node-positive breast cancer  or in high-risk postmenopausal breast cancer  in adjuvant studies. In contrast, Berns et al. found that in 401 patients with metastatic breast cancer, p53 expression as measured by enzyme immunoassay of cytoplasmic extracts from primary tumours was a predictor of tamoxifen resistance . Our results indicate that p53 protein accumulation by IHC was predictive of endocrine therapy resistance and decreased post-relapse survival in metastatic breast cancer. The antibody for p53 that Elledge et al.  used was also used in our study. Their results may have differed from ours because not only tamoxifen, but also aromatase inhibitors and/or LHRH (luteinising hormone-releasing hormone) agonists, were used as endocrine therapy in our study. Further studies to analyse the correlation between response to each endocrine therapy agent and p53 status are necessary to understand the role of p53 in endocrine therapy resistance. Moreover, the conflicting results may be caused by the different evaluation methods of p53 status. Geisler et al. demonstrated that nearly 30% of all mutations in primary breast cancer, in particular those of the nonsense type, are not detected by IHC and that most studies evaluating p53 status by IHC have failed to show a predictive value of p53 for chemotherapy, whereas studies evaluating p53 status by DNA sequencing have reported mutations that predict resistance to chemotherapy . Therefore, mutational analysis of p53 might be helpful in evaluating the association between p53 status and endocrine therapy resistance.
The present study indicates that p53 protein accumulation predicts resistance to endocrine therapy and decreased post-relapse survival in patients with metastatic breast cancer who received first-line treatment with endocrine therapy on relapse. Our data suggest that p53 protein accumulation is helpful in selecting patients who may benefit from endocrine therapy and is a prognostic marker in metastatic breast cancer.
- CMF = cyclophosphamide:
methotrexate, and fluorouracil
This work was supported by Grants-in Aid for Scientific Research from the Ministry of Education, Science, Sports and Culture in Japan 16591267.
- Johnston SR, Head J, Pancholi S, Detre S, Martin LA, Smith IE, Dowsett M: Integration of signal transduction inhibitors with endocrine therapy: an approach to overcoming hormone resistance in breast cancer. Clin Cancer Res. 2003, 9: 524S-532S.PubMedGoogle Scholar
- Schiff R, Massarweh S, Shou J, Osborne CK: Breast cancer endocrine resistance: how growth factor signaling and estrogen receptor coregulators modulate response. Clin Cancer Res. 2003, 9: 447S-454S.PubMedGoogle Scholar
- Elledge RM, Green S, Ciocca D, Pugh R, Allred DC, Clark GM, Hill J, Ravdin P, O'Sullivan J, Martino S, et al: HER-2 expression and response to tamoxifen in estrogen receptor-positive breast cancer: a Southwest Oncology Group Study. Clin Cancer Res. 1998, 4: 7-12.PubMedGoogle Scholar
- Yamauchi H, Stearns V, Hayes DF: When is a tumor marker ready for prime time? A case study of c-erbB-2 as a predictive factor in breast cancer. J Clin Oncol. 2001, 19: 2334-2356.PubMedGoogle Scholar
- Stal O, Borg A, Ferno M, Kallstrom AC, Malmstrom P, Nordenskjold B: ErbB2 status and the benefit from two or five years of adjuvant tamoxifen in postmenopausal early stage breast cancer. Ann Oncol. 2000, 11: 1545-1550. 10.1023/A:1008313310474.PubMedView ArticleGoogle Scholar
- De Laurentiis M, Arpino G, Massarelli E, Ruggiero A, Carlomagno C, Ciardiello F, Tortora G, D'Agostino D, Caputo F, Cancello G, et al: A meta-analysis on the interaction between HER-2 expression and response to endocrine treatment in advanced breast cancer. Clin Cancer Res. 2005, 11: 4741-4748. 10.1158/1078-0432.CCR-04-2569.PubMedView ArticleGoogle Scholar
- Fitzgibbons PL, Page DL, Weaver D, Thor AD, Allred DC, Clark GM, Ruby SG, O'Malley F, Simpson JF, Connolly JL, et al: Prognostic factors in breast cancer. College of American Pathologists Consensus Statement 1999. Arch Pathol Lab Med. 2000, 124: 966-978.PubMedGoogle Scholar
- Hurlimann J, Chaubert P, Benhattar J: p53 Gene alterations and p53 protein accumulation in infiltrating ductal breast carcinomas: correlation between immunohistochemical and molecular biology techniques. Mod Pathol. 1994, 7: 423-428.PubMedGoogle Scholar
- Kerns BJ, Jordan PA, Moore MB, Humphrey PA, Berchuck A, Kohler MF, Bast RC, Iglehart JD, Marks JR: p53 overexpression in formalin-fixed, paraffin-embedded tissue detected by immunohistochemistry. J Histochem Cytochem. 1992, 40: 1047-1051.PubMedView ArticleGoogle Scholar
- Elledge RM, Allred DC: The p53 tumor suppressor gene in breast cancer. Breast Cancer Res Treat. 1994, 32: 39-47. 10.1007/BF00666204.PubMedView ArticleGoogle Scholar
- Yamashita H, Nishio M, Toyama T, Sugiura H, Zhang Z, Kobayashi S, Iwase H: Coexistence of HER2 over-expression and p53 protein accumulation is a strong prognostic molecular marker in breast cancer. Breast Cancer Res. 2004, 6: R24-30. 10.1186/bcr738.PubMedPubMed CentralView ArticleGoogle Scholar
- Lowe SW, Bodis S, McClatchey A, Remington L, Ruley HE, Fisher DE, Housman DE, Jacks T: p53 status and the efficacy of cancer therapy in vivo. Science. 1994, 266: 807-810.PubMedView ArticleGoogle Scholar
- Kandioler-Eckersberger D, Ludwig C, Rudas M, Kappel S, Janschek E, Wenzel C, Schlagbauer-Wadl H, Mittlbock M, Gnant M, Steger G, et al: TP53 mutation and p53 overexpression for prediction of response to neoadjuvant treatment in breast cancer patients. Clin Cancer Res. 2000, 6: 50-56.PubMedGoogle Scholar
- Thor AD, Berry DA, Budman DR, Muss HB, Kute T, Henderson IC, Barcos M, Cirrincione C, Edgerton S, Allred C, et al: erbB-2, p53, and efficacy of adjuvant therapy in lymph node-positive breast cancer. J Natl Cancer Inst. 1998, 90: 1346-1360. 10.1093/jnci/90.18.1346.PubMedView ArticleGoogle Scholar
- Geisler S, Lonning PE, Aas T, Johnsen H, Fluge O, Haugen DF, Lillehaug JR, Akslen LA, Borresen-Dale AL: Influence of TP53 gene alterations and c-erbB-2 expression on the response to treatment with doxorubicin in locally advanced breast cancer. Cancer Res. 2001, 61: 2505-2512.PubMedGoogle Scholar
- Aas T, Borresen AL, Geisler S, Smith-Sorensen B, Johnsen H, Varhaug JE, Akslen LA, Lonning PE: Specific P53 mutations are associated with de novo resistance to doxorubicin in breast cancer patients. Nat Med. 1996, 2: 811-814. 10.1038/nm0796-811.PubMedView ArticleGoogle Scholar
- Rahko E, Blanco G, Soini Y, Bloigu R, Jukkola A: A mutant TP53 gene status is associated with a poor prognosis and anthracycline-resistance in breast cancer patients. Eur J Cancer. 2003, 39: 447-453. 10.1016/S0959-8049(02)00499-9.PubMedView ArticleGoogle Scholar
- Clahsen PC, van de Velde CJ, Duval C, Pallud C, Mandard AM, Delobelle-Deroide A, van den Broek L, Sahmoud TM, van de Vijver MJ: p53 protein accumulation and response to adjuvant chemotherapy in premenopausal women with node-negative early breast cancer. J Clin Oncol. 1998, 16: 470-479.PubMedGoogle Scholar
- Bertheau P, Plassa F, Espie M, Turpin E, de Roquancourt A, Marty M, Lerebours F, Beuzard Y, Janin A, de The H: Effect of mutated TP53 on response of advanced breast cancers to high-dose chemotherapy. Lancet. 2002, 360: 852-854. 10.1016/S0140-6736(02)09969-5.PubMedView ArticleGoogle Scholar
- Askmalm MS, Carstensen J, Nordenskjold B, Olsson B, Rutqvist LE, Skoog L, Stal O: Mutation and accumulation of p53 related to results of adjuvant therapy of postmenopausal breast cancer patients. Acta Oncol. 2004, 43: 235-244. 10.1080/02841860410029474.PubMedView ArticleGoogle Scholar
- Andersson J, Larsson L, Klaar S, Holmberg L, Nilsson J, Inganas M, Carlsson G, Ohd J, Rudenstam CM, Gustavsson B, et al: Worse survival for TP53 (p53)-mutated breast cancer patients receiving adjuvant CMF. Ann Oncol. 2005, 16: 743-748. 10.1093/annonc/mdi150.PubMedView ArticleGoogle Scholar
- Geisler S, Borresen-Dale AL, Johnsen H, Aas T, Geisler J, Akslen LA, Anker G, Lonning PE: TP53 gene mutations predict the response to neoadjuvant treatment with 5-fluorouracil and mitomycin in locally advanced breast cancer. Clin Cancer Res. 2003, 9: 5582-5588.PubMedGoogle Scholar
- Knoop AS, Bentzen SM, Nielsen MM, Rasmussen BB, Rose C: Value of epidermal growth factor receptor, HER2, p53, and steroid receptors in predicting the efficacy of tamoxifen in high-risk postmenopausal breast cancer patients. J Clin Oncol. 2001, 19: 3376-3384.PubMedGoogle Scholar
- Berry DA, Muss HB, Thor AD, Dressler L, Liu ET, Broadwater G, Budman DR, Henderson IC, Barcos M, Hayes D, et al: HER-2/neu and p53 expression versus tamoxifen resistance in estrogen receptor-positive, node-positive breast cancer. J Clin Oncol. 2000, 18: 3471-3479.PubMedGoogle Scholar
- Elledge RM, Green S, Howes L, Clark GM, Berardo M, Allred DC, Pugh R, Ciocca D, Ravdin P, O'Sullivan J, et al: bcl-2, p53, and response to tamoxifen in estrogen receptor-positive metastatic breast cancer: a Southwest Oncology Group study. J Clin Oncol. 1997, 15: 1916-1922.PubMedGoogle Scholar
- Archer SG, Eliopoulos A, Spandidos D, Barnes D, Ellis IO, Blamey RW, Nicholson RI, Robertson JF: Expression of ras p21, p53 and c-erbB-2 in advanced breast cancer and response to first line hormonal therapy. Br J Cancer. 1995, 72: 1259-1266.PubMedPubMed CentralView ArticleGoogle Scholar
- Berns EM, Klijn JG, van Putten WL, de Witte HH, Look MP, Meijer-van Gelder ME, Willman K, Portengen H, Benraad TJ, Foekens JA: p53 protein accumulation predicts poor response to tamoxifen therapy of patients with recurrent breast cancer. J Clin Oncol. 1998, 16: 121-127.PubMedGoogle Scholar
- Yamashita H, Nishio M, Kobayashi S, Ando Y, Sugiura H, Zhang Z, Hamaguchi M, Mita K, Fujii Y, Iwase H: Phosphorylation of estrogen receptor alpha serine 167 is predictive of response to endocrine therapy and increases postrelapse survival in metastatic breast cancer. Breast Cancer Res. 2005, 7: R753-764. 10.1186/bcr1285.PubMedPubMed CentralView ArticleGoogle Scholar
- Allred DC, Harvey JM, Berardo M, Clark GM: Prognostic and predictive factors in breast cancer by immunohistochemical analysis. Mod Pathol. 1998, 11: 155-168.PubMedGoogle Scholar
This article is published under license to BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.