PURPOSE: Clear cell ovarian carcinoma (CCOC) is an aggressive disease that often demonstrates resistance to standard chemotherapies. Approximately 25% of CCOC show a strong APOBEC mutation signature. Here, we determine which APOBEC3 enzymes are expressed in CCOC, establish clinical correlates, and identify a new biomarker for detection and intervention.
EXPERIMENTAL DESIGN: APOBEC3 expression was analyzed by immunohistochemistry and RT-qPCR in a pilot set of CCOC specimens (n=9 tumors). The immunohistochemistry analysis of APOBEC3B was extended to a larger cohort to identify clinical correlates (n=48). Dose response experiments with platinum-based drugs in CCOC cell lines and carboplatin treatment of patient-derived xenografts (PDX) were done to address mechanistic linkages.
RESULTS: One DNA deaminase, APOBEC3B, is overexpressed in a formidable subset of CCOC tumors and is low or absent in normal ovarian and fallopian tube epithelial tissues. High APOBEC3B expression associates with improved progression-free survival (p=0.026) and moderately with overall survival (p=0.057). Cell-based studies link APOBEC3B activity and subsequent uracil processing to sensitivity to cisplatin and carboplatin. PDX studies extend this mechanistic relationship to CCOC tissues.
CONCLUSIONS: These studies demonstrate that APOBEC3B is overexpressed in a subset of CCOC and, contrary to initial expectations, associated with improved (not worse) clinical outcomes. A likely molecular explanation is that DNA damage caused APOBEC3B sensitizes cells to additional genotoxic stress by cisplatin. Thus, APOBEC3B is a molecular determinant and a candidate predictive biomarker of the therapeutic response to platinum-based chemotherapy. These findings may have broader translational relevance, as APOBEC3B is overexpressed in many different cancer types.
|Original language||English (US)|
|Number of pages||11|
|Journal||Clinical cancer research : an official journal of the American Association for Cancer Research|
|Early online date||Feb 14 2020|
|State||Published - Jul 1 2020|
Bibliographical notePublisher Copyright:
©2020 American Association for Cancer Research.
PubMed: MeSH publication types
- Journal Article
- Research Support, N.I.H., Extramural
- Research Support, Non-U.S. Gov't