Abstract 1665: Biopsy induced metastasis: Role of SOX4/TGF-β driven EMT and immunosuppressive microenvironment
Authors: Mathenge Edward G. , Dean Cheryl , Clements Derek , Vagharkashani Ahmad , Photopoulos Steffany , Coyle Krysta , Malueth Benjamin A. , Giacomantonio Mike , Nunokawa Anna , Jordan Julie , Gujar Shashi , Marcato Paola , Lee Partick , Giacomantonio Carman A. 
Published: May 2015

As a consequence of advances in digital diagnostic imaging, breast cancers are being diagnosed earlier in their development. These smaller tumors are less likely to be metastatic at time of discovery. The majority of newly diagnosed breast cancers in North America are confirmed using an incisional core needle biopsy (CNB). However an increasing number of studies highlight the pro-metastatic inflammatory and microenvironment changes occurring after incisional procedures on breast cancer tumors. This may account for reported higher incidences of lymph node metastases with increased risk of local recurrence and distant metastasis among patients undergoing incisional procedures.

Evidence from our studies using a metastatic mouse model shows that incisional core needle biopsies lead to increased pulmonary metastasis. To study the mechanism(s) involved we monitored changes in circulating tumor cells (CTC), cytokine levels, variations in gene expression, microenvironment alteration and pulmonary metastatic burden, following CNB.

Gene expression analysis by real-time qPCR showed increased TGF-β expression accompanied by SOX4 upregulation at 3 hours post biopsy (SOX4 is a Master regulator of EMT). This was followed, at 24 hours post biopsy, by significantly increased levels of the SOX4-associated Ezh2 gene and other EMT genes (ZEB2, SNAI2, SNAI3, and CDH2). Monitoring of CTCs over the same time frame showed them to be significantly increased in biopsied mice from 6 to 24 hours post biopsy, indicating continual CTC egress from biopsied tumors. Flow cytometry analysis of tumor microenvironment showed an immunosuppressive microenvironment with increased MDSC levels, reduced CD4+ and CD8+ T cells, macrophage and NKT cell. Interestingly, similar analysis of the Lung microenvironment 4 days later (day 7 post biopsy) revealed an inversion of the tumor situation, in the form of a significant uptick in Th1 type changes described by increased CD4+ and CD8+ type T cells, macrophages and NK cells, as well as increased TNF-β gene expression indicators corresponding to an early response to growth of metastases. We also compared H&E stained histological sections of lungs from biopsied and un-biopsied mice and recorded significant increase in pulmonary metastasis for the biopsied group.

The findings of our study indicate that performance of CNB results in increased metastasis with immunomodulation of the tumor microenvironment and unregulated SOX4/TGF- β. Additional studies are needed to further elucidate the mechanism, and explore mitigating strategies to counter CNB related metastasis.

Citation Format: Edward G. Mathenge, Cheryl Dean, Derek Clements, Ahmad Vagharkashani, Steffany Photopoulos, Krysta Coyle, Benjamin A. Malueth, Mike Giacomantonio, Anna Nunokawa, Julie Jordan, Shashi Gujar, Paola Marcato, Partick Lee, Carman A. Giacomantonio. Biopsy induced metastasis: Role of SOX4/TGF-β driven EMT and immunosuppressive microenvironment. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1665. doi:10.1158/1538-7445.AM2014-1665