Identification of biomarkers associated with metastastic breast cancer to bone by immunohistochemistry on tissue microarrays.
Authors: Nasir I , Brufsky A , Bhargava R , McManus K , Chivukula M 
Published: December 2010

Abstract #2065

Background: Bone is the most common site of breast cancer metastasis. Efforts have been made to understand the complex molecular mechanisms underlying this. It involves invasion, proliferation at metastatic sites, and activity of cytokines (IL1,6,8,11, TNF, and TGFß), chemokines, their receptors (stromal-derived-factor1 and CXC chemokine[CXCR4, also called fusin, involved in HIV tropism]), and matrix metalloproteinases (MMP). Microarray analyses of primary tumors with different metastatic sites have distinct gene expression patterns indicating tumor heterogeneity. Both lung and bone metastasis gene signatures include CXCR4, and MMP1, whereas bone metastasis gene signature also includes IL11. PTHrP, activated by TGFß signaling, also mediate metastasis. A subpopulation of breast cancer cells, expressing CD44 with stem cell properties, was found to promote breast tumor invasion and metastases. Trefoil factor1 (TFF1), a proangiogenic factor, involved in invasion of kidney and colonic cancer cells, has a high correlation with bone metastasis, is expressed under estrogen control, and found in a subset of ER+ breast cancers. New prognostic markers are needed to identify patients at high risk of bone metastases to individualize therapy. This study's aim was, for the first time, to evaluate the expression of selected biomarkers associated with tumor relapse to bone, by immunohistochemistry (IHC) on tissue microarrays (TMA).&#x2028; Materials and Methods: 16 cases of metastastic breast cancer to bone (MBC-B) were retrieved from MWH tumor registry and a TMA with 3-fold redundancy was created (TMA1), consisting of cores with a diameter of 0.6 mm. To study the expression of these markers in primary breast cancers (PBC), a second TMA (TMA2) was created for 63 breast cancers. IHC was performed for selected markers (TFF1,CXCR4, MMP1, PTHrP, CD44, FGFR3, and IL11) on both TMAs. Clinical and other pathologic parameters were available. All patients had received standard chemotherapy/hormonal treatment.&#x2028; Results: In the MBC-B group, 14 cases were infiltrating ductal and 2 cases were infiltrating lobular (average tumor size 2.6cm;range 0.4-8.0cm). 50% (8/16) had axillary lymph node metastases. 94% (15/16) were ER and PR positive and 19% (3/16) were HER2 positive. 44% (7/16) were rapid bone metastasis progressors (&lt;1y) and 56% (9/16) were slow progressors (&gt;1y). Currently, no statistical difference in the expression of markers in MBC-B vs PBC was seen (100% for CXCR4, MMP1, PTHrP, FGFR3, IL11). However, a high expression of ER, CD44, and TFF1 is seen in MBC-B. Ongoing studies are evaluating whether these markers are independent prognostic markers for bone metastases and tumor specific survival.&#x2028; &#x2028; Discussion: We found a high level of expression of CXCR4, MMP1, PTHrP, FGFR3, and IL11 which signifies their importance in both PBC and MBC-B. Overall, expression of ER, CD44, and TFF1 potentially may serve as prognostic markers in identifying, at an early stage, patients at risk of bone metastases.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2065.