Prognostic value of P53, MDM-2, and MUC-1 for patients with inflammatory breast carcinoma

Authors


  • Presented at the Fifteenth International Congress on Anti-Cancer Treatment, Paris, France, February 9–12, 2004.

Abstract

BACKGROUND

Inflammatory breast carcinoma (IBC) is a rare and aggressive malignancy. Therapy for patients with IBC is multidisciplinary, and response to preoperative chemotherapy is considered an important predictor of outcome. Although only a limited number of molecular markers have been investigated in this setting, none has exhibited prognostic value for patients with IBC.

METHODS

Immunohistochemical assays for P53, MDM-2, and MUC-1 were performed retrospectively to evaluate potential correlations between these markers and pathologic response, time to progression (TTP), and overall survival (OS) in 19 patients with IBC.

RESULTS

After a median follow-up period of 46 months, patients with tumors that overexpressed P53 and did not express MUC-1 had a significantly shorter median TTP and median OS compared with other patients.

CONCLUSIONS

Expression of P53 and MUC-1 may be predictive of treatment efficacy and outcome for patients with IBC. Furthermore, these two markers may represent novel therapeutic targets in such patients. Cancer 2004. © 2004 American Cancer Society.

Inflammatory breast carcinoma (IBC) is a rare and aggressive tumor that possesses the clinical and biologic characteristics of a rapidly proliferating malignancy. For reasons that have not been elucidated, the incidence of IBC is increasing more rapidly compared with the incidence of other breast malignancies. According to recent data from the National Cancer Institute Surveillance, Epidemiology, and End Results Program, the incidence of IBC stands at 0.7 cases per 100,000 person-years.1 Recent studies analyzing outcomes in patients with IBC and patients with locally advanced noninflammatory breast disease have revealed a significant advantage in terms of OS for the latter group, and this finding clearly suggests that there are differences in tumor biology between these two groups.2 The management strategy for patients with IBC has evolved into a multimodality approach involving induction chemotherapy (IC), surgery, and radiotherapy (XRT).3, 4 This approach has led to changes in the natural history of IBC, as evidenced by improvements in local control and patient survival.5, 6 Nonetheless, clinical trials have indicated that poor pathologic response (and particularly residual lymph node involvement) following IC may be the most powerful predictor of local and systemic recurrence.7, 8

Few molecular markers have been found to be characteristic of IBC, and none has exhibited prognostic value with respect to treatment efficacy or outcome.9P53 is the most commonly altered gene in breast carcinoma, and nuclear expression of P53 is associated with increased tumor aggressiveness, early metastases, anthracycline resistance, and reduced survival.10 The MDM-2 oncoprotein plays a significant role in promoting the degradation of nuclear P53 in tumor cells; P53 and MDM-2 participate in an autoregulatory feedback loop in which P53 stimulates MDM-2 expression and MDM-2 inhibits the activity of P53 by blocking P53 transcription, thereby leading to the nuclear export and degradation of P53. Because of its inhibitory effect on P53, MDM-2 overexpression is associated with uncontrolled cell proliferation.11

Human mucin 1 (MUC-1) is a mucin glycoprotein that is expressed in 90% of all breast adenocarcinomas.12 It is the most common epithelial antigen in malignant breast cells and represents a valid target for immunomodulatory treatment.13 MUC-1-associated antigens are considered to be the most sensitive breast tumor markers.14

In the current study, we set out to retrospectively evaluate the expression of P53, MDM-2, and MUC-1 and to assess potential correlations between these markers and clinical response to IC, time to progression (TTP), and overall survival (OS) in patients with IBC.

MATERIALS AND METHODS

We reviewed the cases of 33 consecutive patients with documented primary IBC who were treated at The University of Texas M. D. Anderson Cancer Center (Houston, TX) between January 1995 and October 1997. A pretreatment diagnostic biopsy was performed for all patients. In addition, assays of estrogen receptor (ER) and progesterone receptor (PgR) expression were performed. Nineteen patients had histologic material that was considered adequate for additional immunohistochemical studies, and these patients constituted the current study cohort. The diagnostic procedures performed for these patients included core biopsy (n = 15) and skin biopsy (n = 4). All patients had received an IC regimen containing 5-fluorouracil, doxorubicin, and cyclophosphamide, and 10 patients (53%) had also received paclitaxel. Following IC, all patients underwent mastectomy and XRT.

We retrospectively assessed the expression of P53, MDM-2, and MUC-1 in pretreatment specimens using immunohistochemical methods. All investigations were performed after approval was granted by an institutional review board. Histologic sections measuring 4 μm in thickness were cut from paraffin blocks and incubated overnight at 4 °C with a 1:50 dilution of mouse monoclonal antibodies against P53 (DO7; Dako, Carpinteria, CA), MUC-1 (VU3C6; Chemicon, Temecula, CA), or MDM-2 (SMP14; Dako). The expression of a given marker was arbitrarily reported to be positive if ≥ 10% of cells in a section stained positively for that marker; staining intensity was scored as 1+, 2+, or 3+ (Fig. 1). Clinical response was defined as a complete response (CR) or a partial response (PR) according to the criteria described by Miller et al.15

Figure 1.

Marker expression in three representative inflammatory breast carcinoma specimens. (A) Diffuse nuclear P53 immunoreactivity. (B) Moderate nuclear expression of MDM-2. (C) Intense cytoplasmic and membranous staining for MUC-1.

The Kaplan–Meier product-limit method was used to assess differences between patient groups in terms of TTP and OS, and the log-rank test and the stratified log-rank test were used to compare survival estimates between groups. OS was measured in months from the date of diagnosis to the date of death or last follow-up. TTP was measured in months from the date of diagnosis to the date of recurrence or last follow-up. All statistical analyses were performed using SPSS software (Version 12.0; SPSS Inc., Chicago, IL).

RESULTS

Patient characteristics are summarized in Table 1. The median age at diagnosis was 47 years (range, 33–62 years), and no patient experienced a pathologic complete response. Eleven patients (58%) had hormone receptor (ER/PgR)-negative disease. Sixteen patients (84%) had P53-positive tumors, which exhibited diffuse, granular nuclear staining for P53. Cytoplasmic staining was not found in any of the tumors that were investigated. Fifteen patients (79%) had high MUC-1 expression levels (2+ or 3+), and 5 patients (26%) had MDM-2-positive disease. Nine patients (47%) experienced an objective response (CR or PR) to IC. All patients underwent mastectomy, and only one patient opted not to undergo axillary lymph node dissection.

Table 1. Patient and Tumor Characteristics
CharacteristicNo. of patients (%)
  1. FAC: 5-fluorouracil, doxorubicin, and cyclophosphamide.

Age (yrs) 
 < 5013 (68)
 ≥ 50 6 (32)
Estrogen receptor status 
 Negative14 (74)
 Positive 5 (26)
Progesterone receptor status 
 Negative16 (84)
 Positive 3 (16)
Histologic type 
 Ductal15 (79)
 Lobular 4 (21)
Lymphovascular invasion 
 No 0 (0)
 Yes19 (100)
Modified nuclear grade 
 2 6 (32)
 313 (68)
Chemotherapy 
 FAC 9 (47)
 FAC + taxane10 (53)
Clinical response to chemotherapy 
 Complete response 1 (5.2)
 Partial response 8 (42)
 < partial response10 (53)

P53-positive tumors preferentially had negative ER status (P = 0.01). In addition, all P53-negative tumors had negative MDM-2 status. MDM-2 expression was found to be associated with ER expression; 33% of all ER-positive tumors had negative MDM-2 status, whereas 86% of all ER-negative tumors had negative MDM-2 status (P = 0.02). P53 status was the most powerful predictor of residual disease in the lymph nodes (n = 16 [positive P53 status] vs. n = 1 [negative P53 status]; P = 0.01). Furthermore, with regard to response, patients who experienced a PR or a CR were more likely to have high MUC-1 expression levels (2+ or 3+) compared with patients who had less favorable responses, although this difference was not statistically significant (P = 0.3).

After a median follow-up period of 46 months, there were 14 cases of recurrence (74%) and 13 deaths (69%). Median TTP and median OS were significantly poorer for patients with P53-positive disease compared with patients with P53-negative disease (TTP, 14.5 months vs. not reached; OS, 40.9 months vs. not reached; P = 0.02 and P = 0.03, respectively) and for patients with MUC-1-negative disease compared with patients with MUC-1-positive disease (TTP, 11 months vs. 20 months; OS, 23 months vs. 53.5 months; P = 0.02 and P = 0.001, respectively) (Table 2). Clinical response was not predictive of long-term outcome. None of the 3 patients with P53-negative disease and high MUC-1 expression levels (2+ or 3+) experienced recurrence, whereas all 4 patients with P53-positive disease and low MUC-1 expression levels (negative or 1+) experienced recurrence and subsequently died of disease (P = 0.01).

Table 2. Expression of P53, MDM-2, and MUC-1 and Time to Recurrence and Death in Patients with Inflammatory Breast Carcinoma
CharacteristicNo. of patients (%)Median time to recurrence (mos)Log-rank PMedian time to death (mos)Log-rank P
  1. NR: not reached

Histologic type     
 Ductal15 (79)18.60 51.61 
 Lobular 4 (21)10.970.640.940.97
P53 status     
 Negative 3 (16)NR NR 
 Positive16 (84)14.260.0240.940.03
MDM-2 status     
 Positive 5 (26)18.60 40.94 
 Negative14 (74)14.520.346.360.2
MUC-1 status     
 Negative/1+ 4 (19)10.97 23.00 
 2+/3+15 (79)20.070.0253.520.001
P53/MUC-1 status     
 P53-negative, MUC-1 2+ or 3+ 3 (16)NR NR 
 P53-positive, MUC-1-negative or 1+ 4 (21)10.97 23.00 
 P53-positive, MUC-1 2+ or 3+12 (63)14.520.0144.160.02
P53/MDM-2 status     
 Negative/negative 2 (11)NR NR 
 Positive/negative11 (58)13.83 44.16 
 Positive/positive 5 (26)18.600.0640.940.07

DISCUSSION

IBC is an invasive malignancy characterized by high histologic and nuclear grades and by aggressive features such as aneuploidy, high S-phase fraction, negative ER status, and elevated expression of epidermal growth factor and ErbB-2.9, 16, 17 Nuclear exclusion and cytoplasmic sequestration due to missense mutations represent a potential mechanism for P53 inactivation, which has been reported in 37% of breast carcinoma cases.17, 18 P53 overexpression has been found to be associated with favorable responses to IC.19 Azis et al.9 assessed P53 expression in 40 patients with IBC and in a matched cohort of patients with other types of breast malignancy and found that P53 was expressed in 70% of all IBCs, compared with 48% of all noninflammatory breast tumors. MDM-2 is critical in the regulation of P53; inhibition of the phosphatidylinositol 3-kinase/Akt signal that regulates the translocation of MDM-2 to the nucleus results in persistent P53 activation.20–22

The results of the current study confirm that P53 is overexpressed in a large percentage of primary IBCs. In contrast, we found that only 26% of patients in the current cohort had MDM-2-positive disease. It is noteworthy that all P53-negative tumors also had negative MDM-2 status and that consideration of MDM-2 status did not augment the prognostic significance of P53 status. As expected, compared with P53-negative tumors, P53-positive tumors exhibited more aggressive biologic behavior and were associated with a shorter median TTP and a shorter median OS. All patients with P53-negative/MDM-2-negative disease remained alive at the time of the current report. This finding, which hints at novel strategies for restoring P53 function, suggests that P53 degradation may be modulated by the inhibition of MDM-2, with this modulatory effect potentially compensating for the degradative inactivation of P53.23, 24

The human epithelial mucin MUC-1 is a high–molecular weight glycoprotein that is characterized by heavy glycosylation and is expressed in approximately 90% of all invasive breast tumors.12, 14 MUC-1 differs from other tumor-associated antigens in that it is strongly recognized by cytotoxic T lymphocytes; this feature makes MUC-1 an important molecule with respect to antitumor immune responses and immunotherapy.25–27 Seventy-nine percent of patients in the current study had tumors that strongly expressed MUC-1, and these patients had a significant advantage over others in terms of TTP and OS. The observation of poor outcomes in patients with reduced or absent MUC-1 expression suggests that a dysfunction related to T cell–mediated immunity may contribute to the development of IBC. Further investigation of this possibility is warranted.

In conclusion, the current retrospective analysis demonstrates that expression of P53 and MUC-1 may be predictive of treatment efficacy and outcome for patients with IBC. Consequently, these markers may be of value in assessing therapeutic options for individual patients with IBC.

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