Abstract A41: The heat shock transcription factor HSF1 induces ovarian cancer epithelial-mesenchymal transition in a 3-D spheroid growth model

Ovarian cancer is the most lethal gynecological cancer, with over 200,000 women diagnosed each year and over half of those cases leading to death. These poor statistics are related to a lack of early symptoms and inadequate screening techniques. This results in the cancer going undetected until later stages when the tumor has metastasized through a process that requires the epithelial to mesenchymal transition (EMT). In lieu of traditional monolayer cell culture, EMT and cancer progression in general is best characterized through the use of 3D spheroid models. Compared to other cancers, ovarian cancer has very limited treatment options to date, with cisplatin and paclitaxel being the most common and efficient. Recently, a significant increase in heat shock factor 1 (HSF1) expression has been found in highly malignant ovarian cancer. HSF1 is the regulator of the heat shock response (HSR) and promotes the transcription of heat shock proteins (HSPs). Previous studies have shown that HSF1-induced chaperone activity may act to stabilize multiple oncogenes within many different cancer types. This leads to cancer proliferation, reduced apoptosis, and metastasis. In this study, we examine gene expression changes through microarray analysis in spheroid versus monolayer ovarian cancer cells treated with TGFβ to induce EMT. Interestingly, EMT and stress response pathways, including the heat shock response, were all significantly affected by 3D growth. HSF1 knockdown was utilized in both 2D and 3D cultures to further study this response. HSF1 knockdown is shown to inhibit ovarian cancer progression in both monolayer and spheroid model cells. Moreover, HSF1 knockdown in spheroid cells has a significantly greater impact on EMT markers than it does in 2D cultures. This indicates HSF1 may be a utilized as a target for chemotherapeutics in ovarian cancer patients and could potentially have implications in other such hormonal cancers. Citation Format: Trillitye Paullin, Chase Powell, Menzie Christopher, Robert Hill, Christopher Martyniuk, Sandy Westerheide. The heat shock transcription factor HSF1 induces ovarian cancer epithelial-mesenchymal transition in a 3-D spheroid growth model. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: Exploiting Vulnerabilities; Oct 17-20, 2015; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(2 Suppl):Abstract nr A41.