The Role of RUNX3 in Chemoresistance in Epithelial Ovarian Cancer

• Author / Creator

  Zepeda, Nubia I

• Chemoresistance is one of the major hurdles to induce a cure in patients with epithelial ovarian cancer (EOC). RUNX3, belonging to the family of RUNX transcription factors, has been shown to act in an oncogenic manner by promoting proliferation and colony formation when overexpressed, in EOC. However, to date the role of RUNX3 in chemoresistance in EOC has not been studied. Based on its oncogenic role in EOC, we want to determine whether RUNX3 contributes to chemoresistance in EOC. In our study we found that RUNX3 expression is elevated in human EOC samples when compared to non-cancerous ovarian cells. RUNX3 expression is variable in EOC cell lines. Interestingly A2780s cells, a cisplatin-sensitive ovarian adenocarcinoma cell line, show little expression of RUNX3 at the protein level. A2780cp cells, which were derived from A2780s cells by exposure to step-wise increasing doses of cisplatin, show high expression of RUNX3. In A2780s and A2780cp cells, treatment with carboplatin increases the expression of RUNX3 at the protein level. When RUNX3 is overexpressed in EOC cells, cells become slightly more resistant to carboplatin treatment. When we knock down the expression of RUNX3 in A2780cp cells, no effect on cell sensitivity to carboplatin is observed. However, dominant-negative (dn) expression of RUNX3 in A2780cp cells made cells more sensitive to the effects of carboplatin. The dn form may be binding to and occupying the sites that RUNX family members recognize, or binding to the common co-factor CBFβ. Based on these results, we conclude that RUNX3 plays a minor role in chemoresistance when overexpressed in EOC and that other factors, such as other RUNX family members, may be compensating for the loss of RUNX3 when it is knocked down. In the future, it would be interesting to block all the RUNX family members, and observe whether chemoresistant cells become more sensitive to carboplatin treatment. Next we took a systematic approach to understanding chemoresistance by examining the paired human EOC cell lines, A2780s and its derivative A2780cp, using a microarray analysis. To identify networks and pathways that may be key during acquired chemoresistance we conducted an extensive literature search and put the data into Ingenuity Pathway Analysis (IPA) software. Our microarray and IPA suggest that Wnt signaling may be upregulated in A2780cp cells, although further experiments are needed to confirm this. In the future we plan to modulate the canonical Wnt pathway in A2780cp and A2780s cells, and determine whether activation of the canonical Wnt pathway is playing a role in chemoresistance in EOC.

• Subjects / Keywords

  • Ovary
  • RUNX3
  • Cancer

• Graduation date

  Fall 2014

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3K931F2K

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.