Abstract P4-04-24: Metastatic lymph node fibroblasts maintain similar profile of stromal biomarkers registered in primary breast carcinomas

Abstract

Abstract Background: Lymph node metastasis is the predominant dissemination route of breast carcinoma (BC) and remains as an important prognostic indicator of this disease. Several studies demonstrated a similar gene profiling or gene/biological markers assessed by immunohistochemistry in neoplastic epithelial cells at both sites. Recent evidence pointed that cancer associated fibroblasts (CAFs) play a critical role in breast cancer progression and migration. The evidence of CAFs in close association to epithelial tumor cells within lymph node metastasis raised the possibility of a common source of CAFs in these two lesions. However, little is known about the differentially expressed genes or proteins between fibroblasts of the primary tumor and its nodal metastasis. The contribution of CAFs in lymph node colonization is still unknown. Objective: Our aim was to compare the profile of biomarkers between fibroblasts in lymph nodes and those found in the primaries. We compared differences in frequency of activated CAFs through the expression of α-SMA and S100A4 in 43 matched pairs of invasive breast carcinomas and respective macro-metastatic lymph nodes arrayed in TMAs. We also investigated a panel of immunohistochemical biomarkers associated to TGFβ1 (that induces α-SMA and myofibroblast differentiation in CAFs) including CXCR4, pAKT, pm-TOR and c-myc. In addition the frequency of all these markers were assessed in samples of matched disease free lymph nodes obtained from the same patients (which contain fibroblastic reticular cells, limited to the exterior capsule). Results: CAFs characterization confirmed the positive expression of α-SMA (approximately 50%) and S100A4 (100%) on fibroblasts of both sites in contrast to uninvolved lymph nodes, which were uniformly negative. As expected, CAFs were ER, PR, Her-2, CD9 and p53 negative at both sites. As KI67 labeling rate was always lower than 10% in fibroblasts they were considered negative. Comparison between fibroblasts from the stromal component of the primaries and respective lymph nodes indicated that the frequency of TGFβ1, CXCR4 and pAKT positivity was similar whereas a significant lower rate of c-myc and pm-TOR frequency was observed in the metastatic lymph nodal fibroblasts. All biological markers were negative in normal lymph nodes highlighting their association with activated fibroblasts. None of the markers showed association with presence/absence of lymph node metastasis or with other clinic-pathological parameters. Primary carcinomas lacked any potential associations among the evaluated biological markers in fibroblast cells, however, in the stromal tissue of lymph nodes, significant relationships between TGFβ1 and CXCR4, pAKT and c-myc, were observed. Conclusion: Our results indicated the presence of activated fibroblasts expressing α-SMA and S100A4 in fibroblasts of breast cancer primaries as well in their matched metastatic lymph nodes. High concordance for the expression of the analyzed biomarkers in matched pairs of breast cancer primaries and metastatic lymph nodes suggested the maintenance of a similar supportive microenvironment in metastatic sites. Financial Support: FAPESP and CNPq. Citation Format: Fiorita GL Mundim, Fatima S Pasini, Suely Nonogaki, Fernando A Soares, M Mitzi Brentani, Angela F Logullo. Metastatic lymph node fibroblasts maintain similar profile of stromal biomarkers registered in primary breast carcinomas [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P4-04-24.