The Nuclear Transcription Factor κB/bcl-2 Pathway Correlates with Pathologic Complete Response to Doxorubicin-Based Neoadjuvant Chemotherapy in Human Breast Cancer

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Abstract
Purpose: Molecular factors involved in apoptosis may affect breast cancer response to chemotherapy. Herein, we studied the nuclear factor κB (NF-κB)/bcl-2 pathway to determine whether or not activation of this antiapoptotic pathway was associated with a poor response of human breast cancer to anthracycline-based neoadjuvant chemotherapy. Experimental Design: We studied 82 human breast cancer samples from patients treated with neoadjuvant doxorubicin-based chemotherapy and studied whether or not nuclear location of the transcription factor NF-κB was associated with expression of bcl-2 and bax and whether or not expression of these proteins correlated with chemotherapy response. Protein expression was measured with immunohistochemical staining. A dedicated breast cancer pathologist who was unaware of the clinical outcome data dichotomized the slides as positive or negative based on the presence or absence of cytoplasmic staining for bcl-2 and bax or nuclear staining for NF-κB. Results: Sixty-one percent of the tumors were positive for bcl-2, 85% were positive for bax, and 16% were positive for NF-κB. All bcl-2-positive tumors were also bax positive (P < 0.0001) and all NF-κB-positive tumors were both bcl-2 positive (P = 0.001) and bax positive (P = 0.113). Eleven of the 82 patients (13%) had a pathologic complete response (pCR) to chemotherapy. Patients with positive staining tumors for any of the markers less commonly achieved a pCR to chemotherapy than those with negative tumor staining. The pCR rates were NF-κB positive 0% (0 of 13) versus NF-κB negative 13% (11 of 69; P = 0.130); bcl-2 positive 4% (2 of 49) versus bcl-2 negative 27% (9 of 33; P = 0.004); and bax positive 6% (4 of 69) versus bax negative 58% (7 of 12; P < 0.001). Conclusion: We conclude that nuclear localization of NF-κB correlates with bcl-2 and bax expression and that the NF-κB/bcl-2 pathway may be associated with a poor response to neoadjuvant doxorubicin-based chemotherapy.