αB‐crystallin as a marker of lymph node involvement in breast carcinoma

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Abstract
BACKGROUND It was found previously that αB‐crystallin, a small heat‐shock protein, was overexpressed in a metastatic variant of the GI101A human breast carcinoma cell line. The objective of the current study was to determine whether the expression of αB‐crystallin in primary breast carcinomas was associated with lymph node metastasis and survival. METHODS Expression of αB‐crystallin was measured in human breast carcinoma cell lines by immunoblotting. Expression in human breast carcinomas was evaluated by immunohistochemical staining of tissue microarrays that contained samples from 317 patients with lymph node–negative breast carcinoma and 291 patients with lymph node–positive breast carcinoma. RESULTS It was found that αB‐crystallin was expressed constitutively in certain breast carcinoma cell lines, including those that were capable of metastasizing in immunodeficient mice. Expression of αB‐crystallin in human tissue samples was associated strongly with lymph node involvement (P < 0.0001; chi‐square test) and, to a lesser degree, with high nuclear grade (P = 0.05). Increased intensity of expression was correlated with shorter survival (P = 0.0091; log‐rank test). Multivariate analysis indicated that αB‐crystallin expression was not independent of lymph node status as a predictor of survival. CONCLUSIONS The data obtained in the current study revealed a strong association between high expression levels of αB‐crystallin in primary breast carcinoma specimens and lymph node involvement. Further studies will be needed to prospectively elucidate the role of this novel tumor marker as a clinical prognostic marker in local and locally advanced breast carcinoma as well as its potential status as a new target for therapy in patients with breast carcinoma. Cancer 2004. © 2004 American Cancer Society.