Jaguars are near threatened throughout their entire geographic range and endangered inthe United States. Wild jaguars are threatened by habitat loss and other human impacts, andmaintaining a healthy breeding population in zoological institutions is important for survival.We performed a retrospective analysis of reproductive tract and mammary gland lesionsfrom 56 jaguars housed in North American zoological institutions and found a high prevalence(26 of 49 jaguars; 53%) of ovarian papillary cystadenocarcinomas (OC) in aged jaguars (mean17 years; range 8-27 years), including some that were of reproductive age. Neoplasms werebilateral, had stromal invasion, and were histologically similar to high-grade serous OC inhumans. OC is a significant cause of mortality in jaguars due to metastatic implantationthroughout the peritoneal cavity. This neoplasm is very rare in domestic cats, and has not beenreported in other zoo or wild felids. Other neoplasms in zoo felids, including jaguars, such asendometrial carcinoma and mammary carcinoma, are associated with the use of exogenousprogestin contraceptives like melengestrol acetate (MGA). In contrast, we found that OC injaguars were not associated with exogenous progestin exposure. Additionally, pedigree analysisof affected jaguars was suggestive of an autosomal dominant pattern of inheritance, similar tohereditary breast and ovarian cancer in humans. In line with these findings, the centralhypothesis of this dissertation is that the high prevalence of ovarian carcinomas in jaguars isassociated with a germline mutation in BRCA1, BRCA2, or other tumor suppressor gene knownto be involved in human hereditary breast and ovarian cancer. To elucidate the genetic mechanisms of ovarian carcinoma in jaguars, we first assessedthe genetic diversity of the North American zoo population overall compared to reported wildjaguar populations. Using novel universal primer sequences, we created a full multiplex oftwelve tetra- or pentanucleotide microsatellite markers that have not previously been describedfor use in the jaguar. We found that genetic diversity has been maintained in the NorthAmerican zoo population, and that population heterozygosity and allelic diversity werecomparable to reported wild jaguar populations in Central and South America. This set ofmicrosatellite markers also has cross-species utility in other felid species.To evaluate candidate cancer genes for germline mutations associated with ovariancarcinoma, we used a targeted next generation sequencing approach to sequence the codingregions of 276 cancer genes in paired ovarian carcinoma and normal jaguar tissues. We found amissense germline variant in BRCA2 exon 11 resulting in a nonconservative amino acid change(c.3732C>G_p.Ser1248Arg) that was present in all jaguars with ovarian carcinoma, as well assome jaguars in the unaffected zoo population. This variant has also been reported in humanswith hereditary breast and ovarian cancer, and is of unknown functional significance. We testedthe functional significance of this variant using a CRISPR/CAS strategy to knock-in the S1248Rsubstitution into human embryonic kidney (HEK293T) cells. We also generated BRCA2 -/- cells,and evaluated relative DNA repair ability by measuring percentage of cell viability whenexposed to cisplatin, a DNA-damaging agent. We found that cells harboring the S1248R varianthad intermediate cisplatin sensitivity at high concentrations compared to wild type andBRCA2 -/- cells. Jaguars represent a valuable natural model of ovarian carcinoma. Evaluatingjaguar OC-associated variants in genes such as BRCA2 contributes to the understanding ofBRCA2 function overall, as well as the pathogenesis of OC in both jaguars and humans.
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