Abstract P4-04-23: Epithelial and stromal components are equivalently affected in breast fibroepithelial progression. A gene expression analysis of phyllodes and fibroadenomas tumors
Authors: Logullo Angela F , Planila Mabel , Napolitano Elisa , Soares Fernando A , Carraro Dirce 
Published: May 2015

Rationale-Phyllodes tumours (PTs) account for 0,5 to 1% of all breast lesions and, analogous to fibroadenomas (FA), are considered true biphasic neoplasms. However, unlike in FA, their stromal element is more cellular and may outgrow the epithelium, and PT may recur locally and can undergo malignant progression to sarcoma and metastasize. Recent evidence emphasize that epithelium and stroma interactions are critical for tumour development and progression, but molecular alterations in both, epithelial and stromal cells, in the arising of PT onset is not well characterized. Thus, in order to contribute for the identification of the molecular events involved in PT tumorigenesis, we performed gene expression analysis of both types of cells captured from PT and FA.

Methods- Epithelial (EpC) and stromal cells (StC) from 13 PT and 3 FAs were separately submitted to laser capture microdissection (LCM) by CapSure HS™ Arcturus®. Procedures were performed in 10 min to prevent RNA degradation. RNA was extracted using the Pico Pure RNA Isolation Kit™ Arcturus® and was twice amplified the first as described in Castro et al., 2008 with adaptation and the second using low input Quick-Amp Labeling kit* and hybridized to the microarray slide SurePrint G3 Hmm 60K*. Signals were captured by Scanner Agilent Bundle model B* and Agilent Feature Extraction (v 10.7.1) program*and data was analyzed by genespring GX12.1 software* (*Agilent Technologies,USA). A Fold Change ≥2,0 and p≤0,05 were considered significant.

RESULTS: Flag quality filter determined 8.067 coding probes. Differentially expressed genes (DEG) between PT and FA were assessed with data from EpC and StC captured cells separately. A total of 3386 DEG were identified in EpC, and 1910 were up regulated in PT. SC samples revealed 2.619 probes with significant difference among them 1.616 up regulated in PT. Hierarchical clustering based on the DEG from EpC and StC, separately, could not discriminate between TP and FA samples. When low grade PT (n=7) were compared to high grade PT (n=6) the universe of DEG was smaller: EpC derived samples revealed 30 probes with only 14 up regulated in high grade PTs, and StC samples revealed 6 up regulated genes within only 10 probes with DEG in PT. Conclusion: EpC are genetically altered as much as StC in breast fibroepitelial lesions carcinogenesis. Low grade and high grade PTs are similar in RNA and gene expression level. DEGs identified are potential diagnostic targets. Moreover, EpC and StC components seem to share main affected gene pathways, suggesting a common carcinogenesis process.

Citation Format: Angela F Logullo, Mabel Planila, Elisa Napolitano, Fernando A Soares, Dirce Carraro. Epithelial and stromal components are equivalently affected in breast fibroepithelial progression. A gene expression analysis of phyllodes and fibroadenomas tumors [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 P4-04-23.