Expression (Exp) of FIP200 and Rb in breast cancer (BreastCA) metastasis (met) to the brain.

Abstract

222 Background: BreastCA is the 2nd leading cause of cancer deaths in women in the US. Although the outcome for BreastCA with brain met remains poor, there is significant variation in overall survival (OS). Yet, there are no markers or models to predict OS. FIP200 regulates several pathways. In the nucleus, it inhibits cell proliferation by promoting Rb-1 and p21, and in the cytoplasm it promotes cell survival by inhibiting Pyk2 and regulating autophagy. It has been reported that FIP200 gene is deleted or mutated in 20% of primary BreastCAs, and its Exp is correlated with Rb1 levels. FIP200 Exp, its cellular localization, and gene alterations have not been examined in brain met of any cancer. Methods: Brain met tissues of 21 BreastCA patients (pts) biopsied in our institution between 8/2000 and 3/2010 were obtained and Exp of FIP200 and Rb1 were analyzed. Biopsies were selected based on tissue adequacy and prior diagnosis (Dx) of invasive intra-ductal BreastCA. Immunohistochemistry (IHC) was used to evaluate the localization and Exp levels of FIP200 and Rb1 which in turn were tested as predictors of OS. Genetic alterations in FIP200 and Rb1 were examined after DNA extraction. Results: Median time from Dx to met was 23 (range 0-245) months (mos), and median OS from Dx was 43 (range 6-264) mos. Nuclear Exp of Rb1 in < 30% vs. ≥ 30% of cells were seen in 11 vs. 10 pts. Median OS was 39 (range 6-264) mos for Rb1 Exp < 30% and 47 (range 20-190) mo for Rb1 Exp ≥ 30%. Nuclear Exp of FIP200 in <20% vs. ≥ 20% of cells were seen in 13 vs. 8 pts. Median OS was 39 (range 6-264) mo for FIP200 nuclear Exp <20% and 45 (range 43-122) mo for FIP200 Exp ≥ 20%. DNA analysis of 11 pts for copy number variations and loss of heterozygocity (LOH) showed no deletion mutations in FIP200 or Rb1, loss of p53 in 4 of 11, ErbB2 (Her-2) amplification in 4 of 11, and no EGFR gene mutations. Conclusions: The nuclear Exp of Rb1 in brain met from invasive intra-ductal BreastCA may be linked OS. An expanded study is underway to define whether nuclear FIP200 in >20% of cells correlates with nuclear Rb and OS in BreastCA.