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A Genetic Porcine Model of Cancer.

Schook LB, Collares TV, Hu W, Liang Y, Rodrigues FM, Rund LA, Schachtschneider KM, Seixas FK, Singh K, Wells KD, Walters EM, Prather RS, Counter CM - PLoS ONE (2015)

Bottom Line: To this end, we created a transgenic "oncopig" line encoding Cre recombinase inducible porcine transgenes encoding KRASG12D and TP53R167H, which represent a commonly mutated oncogene and tumor suppressor in human cancers, respectively.Finally, injection of AdCre directly into these oncopigs led to the rapid and reproducible tumor development of mesenchymal origin.Transgenic animals receiving AdGFP (green fluorescent protein) did not have any tumor mass formation or altered histopathology.

View Article: PubMed Central - PubMed

Affiliation: Department of Animal Sciences, University of Illinois, Champaign-Urbana, Illinois, United States of America; Department of Bioengineering, University of Illinois, Champaign-Urbana, Illinois, United States of America; Department of Surgery, University of Illinois, Chicago, Illinois, United States of America.

ABSTRACT
The large size of the pig and its similarity in anatomy, physiology, metabolism, and genetics to humans make it an ideal platform to develop a genetically defined, large animal model of cancer. To this end, we created a transgenic "oncopig" line encoding Cre recombinase inducible porcine transgenes encoding KRASG12D and TP53R167H, which represent a commonly mutated oncogene and tumor suppressor in human cancers, respectively. Treatment of cells derived from these oncopigs with the adenovirus encoding Cre (AdCre) led to KRASG12D and TP53R167H expression, which rendered the cells transformed in culture and tumorigenic when engrafted into immunocompromised mice. Finally, injection of AdCre directly into these oncopigs led to the rapid and reproducible tumor development of mesenchymal origin. Transgenic animals receiving AdGFP (green fluorescent protein) did not have any tumor mass formation or altered histopathology. This oncopig line could thus serve as a genetically malleable model for potentially a wide spectrum of cancers, while controlling for temporal or spatial genesis, which should prove invaluable to studies previously hampered by the lack of a large animal model of cancer.

No MeSH data available.


Related in: MedlinePlus

Injection of AdGFP into transgenic pigs did not induce tumors.The lack of any detectable changes to the injection site on d20 post- injection is shown at the surface (a–c); in underlying tissue (d–f); or upon histological examination (g–i).
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pone.0128864.g005: Injection of AdGFP into transgenic pigs did not induce tumors.The lack of any detectable changes to the injection site on d20 post- injection is shown at the surface (a–c); in underlying tissue (d–f); or upon histological examination (g–i).

Mentions: The first of these, oncopig-1, was administered AdCre intramuscularly into the left hind leg. A tumor mass was detected by day 10 post-injection, which was clearly visible by ultrasound (Table 2 and Fig 4a and 4d). Not only was this tumor rapidly established, but it also grew quickly, reaching a volume of 8 cm2 within 20 days. Pathologic analysis of H&E stained sections of the tumor revealed this tumor to be of mesenchymal origin (Fig 4g and Table 2). Specifically, the tumor was microscopically characterized as a densely cellular, non-encapsulated and locally infiltrative neoplasm. The cells are arranged in bundles, streams and small sheets of supported by a fibrous stroma. Individual neoplastic cells were pleomorphic round to oval to polygonal with single to multiple nuclei. Areas of necrosis and chronic inflammation were scattered within the tumor (Fig 4g). Neoplastic cells were stained positively with vimentin and smooth muscle markers (muscle specific actin and smooth muscle actin). This was a reproducible result, as intramuscular injection of AdCre into the other rear leg similarly yielded a tumor of mesenchymal origin at the site of injection (Table 2). Moreover, tumorigenesis was induced in other littermate offspring, indicating this was not unique to a single animal tested. Specifically, AdCre was injected intramuscularly into two legs and the neck of oncopig-2, resulting in tumor masses at all three injection sites, with pathological analysis of H&E stained sections again supporting a mesenchymal tumor diagnosis (Table 2). Isolation of RNA from the resulting tumor masses was used to monitor the expression of mutant transgenic transcripts (Table 2). Both KRASG12D and TP53R167H transgenes were expressed in tumors excised at autopsy. The expression of mutant over wild type transcripts was elevated in each of the sites monitored. Control non-transgenic animals exposed to AdCre and transgenic pigs exposed to AdGFP did not reveal any tumor masses nor pathological changes (Fig 5).


A Genetic Porcine Model of Cancer.

Schook LB, Collares TV, Hu W, Liang Y, Rodrigues FM, Rund LA, Schachtschneider KM, Seixas FK, Singh K, Wells KD, Walters EM, Prather RS, Counter CM - PLoS ONE (2015)

Injection of AdGFP into transgenic pigs did not induce tumors.The lack of any detectable changes to the injection site on d20 post- injection is shown at the surface (a–c); in underlying tissue (d–f); or upon histological examination (g–i).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4488487&req=5

pone.0128864.g005: Injection of AdGFP into transgenic pigs did not induce tumors.The lack of any detectable changes to the injection site on d20 post- injection is shown at the surface (a–c); in underlying tissue (d–f); or upon histological examination (g–i).
Mentions: The first of these, oncopig-1, was administered AdCre intramuscularly into the left hind leg. A tumor mass was detected by day 10 post-injection, which was clearly visible by ultrasound (Table 2 and Fig 4a and 4d). Not only was this tumor rapidly established, but it also grew quickly, reaching a volume of 8 cm2 within 20 days. Pathologic analysis of H&E stained sections of the tumor revealed this tumor to be of mesenchymal origin (Fig 4g and Table 2). Specifically, the tumor was microscopically characterized as a densely cellular, non-encapsulated and locally infiltrative neoplasm. The cells are arranged in bundles, streams and small sheets of supported by a fibrous stroma. Individual neoplastic cells were pleomorphic round to oval to polygonal with single to multiple nuclei. Areas of necrosis and chronic inflammation were scattered within the tumor (Fig 4g). Neoplastic cells were stained positively with vimentin and smooth muscle markers (muscle specific actin and smooth muscle actin). This was a reproducible result, as intramuscular injection of AdCre into the other rear leg similarly yielded a tumor of mesenchymal origin at the site of injection (Table 2). Moreover, tumorigenesis was induced in other littermate offspring, indicating this was not unique to a single animal tested. Specifically, AdCre was injected intramuscularly into two legs and the neck of oncopig-2, resulting in tumor masses at all three injection sites, with pathological analysis of H&E stained sections again supporting a mesenchymal tumor diagnosis (Table 2). Isolation of RNA from the resulting tumor masses was used to monitor the expression of mutant transgenic transcripts (Table 2). Both KRASG12D and TP53R167H transgenes were expressed in tumors excised at autopsy. The expression of mutant over wild type transcripts was elevated in each of the sites monitored. Control non-transgenic animals exposed to AdCre and transgenic pigs exposed to AdGFP did not reveal any tumor masses nor pathological changes (Fig 5).

Bottom Line: To this end, we created a transgenic "oncopig" line encoding Cre recombinase inducible porcine transgenes encoding KRASG12D and TP53R167H, which represent a commonly mutated oncogene and tumor suppressor in human cancers, respectively.Finally, injection of AdCre directly into these oncopigs led to the rapid and reproducible tumor development of mesenchymal origin.Transgenic animals receiving AdGFP (green fluorescent protein) did not have any tumor mass formation or altered histopathology.

View Article: PubMed Central - PubMed

Affiliation: Department of Animal Sciences, University of Illinois, Champaign-Urbana, Illinois, United States of America; Department of Bioengineering, University of Illinois, Champaign-Urbana, Illinois, United States of America; Department of Surgery, University of Illinois, Chicago, Illinois, United States of America.

ABSTRACT
The large size of the pig and its similarity in anatomy, physiology, metabolism, and genetics to humans make it an ideal platform to develop a genetically defined, large animal model of cancer. To this end, we created a transgenic "oncopig" line encoding Cre recombinase inducible porcine transgenes encoding KRASG12D and TP53R167H, which represent a commonly mutated oncogene and tumor suppressor in human cancers, respectively. Treatment of cells derived from these oncopigs with the adenovirus encoding Cre (AdCre) led to KRASG12D and TP53R167H expression, which rendered the cells transformed in culture and tumorigenic when engrafted into immunocompromised mice. Finally, injection of AdCre directly into these oncopigs led to the rapid and reproducible tumor development of mesenchymal origin. Transgenic animals receiving AdGFP (green fluorescent protein) did not have any tumor mass formation or altered histopathology. This oncopig line could thus serve as a genetically malleable model for potentially a wide spectrum of cancers, while controlling for temporal or spatial genesis, which should prove invaluable to studies previously hampered by the lack of a large animal model of cancer.

No MeSH data available.


Related in: MedlinePlus