Common cancer in a wild animal: the California sea lion ( Zalophus californianus ) as an emerging model for carcinogenesis

Abstract

Naturally occurring cancers in non-laboratory species have great potential in helping to decipher the often complex causes of neoplasia. Wild animal models could add substantially to our understanding of carcinogenesis, particularly of genetic and environmental interactions, but they are currently underutilized. Studying neoplasia in wild animals is difficult and especially challenging in marine mammals owing to their inaccessibility, lack of exposure history, and ethical, logistical and legal limits on experimentation. Despite this, California sea lions ( Zalophus californianus ) offer an opportunity to investigate risk factors for neoplasia development that have implications for terrestrial mammals and humans who share much of their environment and diet. A relatively accessible California sea lion population on the west coast of the USA has a high prevalence of urogenital carcinoma and is regularly sampled during veterinary care in wildlife rehabilitation centres. Collaborative studies have revealed that genotype, persistent organic pollutants and a herpesvirus are all associated with this cancer. This paper reviews research to date on the epidemiology and pathogenesis of urogenital carcinoma in this species, and presents the California sea lion as an important and currently underexploited wild animal model of carcinogenesis.

Peto's paradox and the hallmarks of cancer: constructing an evolutionary framework for understanding the incidence of cancer

“…The study of the cells of different rodent species in culture both supported the expectations of the evolutionary model and revealed novel species-specific anti-cancer strategies (table 1). Furthermore, interest in comparative approaches that exploit data from non-model species are rapidly increasing [26][27][28][29], so that we can anticipate further tests of the evolutionary model. The domestic dog is a species notable for having an extensive dataset and studies of breedspecific differences in cancer risk are already proving to be productive [28][29][30].…”

Comparative oncology: what dogs and other species can teach us about humans with cancer

“…For over half a century, marine mammals have been widely accepted as highly suited sentinels for assessing the health of the world's oceans. The typical lifespan of marine mammals is sufficient to allow assessment of the development of numerous chronic diseases, including cancers [155,156]. The number of marine mammals diagnosed with cancers has been increasing over the past 30 years.…”

Patología comparada de neoplasias en carnívoros salvajes

“…Los leones marinos de California tienen alta prevalencia de carcinomas metastásicos de origen urogenital (UGC), que alcanzó 26% en adultos examinados post-mortem en el Centro de Mamíferos Marinos de California (EEUU), durante un período de 15 años (1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012) (Browning et al, 2015). Neoplasias intraepiteliales y carcinomas in situ se han presentado en el tracto genital (pene, prepucio, cérvix, vagina, útero) de leones marinos de California (Bossart, 2011, Lipscomb et al, 2013.…”

“…Hay cuatro áreas de importancia etiológica, se han explorado basado en los factores de riesgo identificados en otras especies y otros tipos de cáncer (Browning et al, 2015).…”

“…Igualmente, la exposición a contaminantes, en particular al hidrocarburo aromático policíclico (HAP) y a compuestos organoclorados (OC), han sido considerados en la etiología de diversos tipos de cán-cer tanto en los seres humanos, en animales de laboratorio y en la vida silvestre (Browning et al, 2015).…”