Studying Tumor Formation and
21 Regulation in Xenopus
Dieter Tulkens and Kris Vleminckx
CONTENTS
21.1. Historical Background ............................................................................................................................................. 301
21.1.1. Xenopus, from Research Tool in Cell and Developmental Biology to Genetically
Engineered Cancer Model Organism ........................................................................................................ 301
21.1.2. A Diploid Genome Favors Genetic Research in Xenopus tropicalis ........................................................ 302
21.2. Past Observations ..................................................................................................................................................... 302
21.2.1. Early Xenopus Embryogenesis as a Source of Information for Studying Pathways
and Cellular Processes Involved in Cancer Initiation and Progression ..................................................... 302
21.2.2. Naturally Occurring Tumors in Xenopus .................................................................................................. 302
21.2.3. Induced Tumor–Like Structures................................................................................................................ 302
21.2.4. T umor–Immune System Interactions ........................................................................................................ 303
21.2.5. Genetically Engineered Xenopus Models ................................................................................................. 303
21.3. Challenges to Ov ercome .......................................................................................................................................... 303
21.4. Genetically Engineered Xenopus Models for Cancer Research .............................................................................. 303
21.4.1. Generation of Clinically Rele vant GEXMs .............................................................................................. 303
21.4.2. T ALEN-Mediated TSG Disruption as a First Genetic Xenopus tropicalis Cancer Model ...............................304
21.4.3. CRISPR/Cas9 Cancer Modeling in Xenopus tropicalis............................................................................ 305
21.5. Application Potential of Xenopus tropicalis Cancer Modeling................................................................................ 305
21.5.1. GEXM for Identifcation of No vel Tumor Dependencies ......................................................................... 305
21.5.2. GEXMs as Tool for Novel Anti-Cancer Compound Validation ................................................................ 306
21.6. Current and Future Xenopus tropicalis Cancer Modeling Methodologies .............................................................. 307
21.6.1. Tools for In Vivo Monitoring of Tumor Progression ................................................................................. 307
21.6.2. Ov erview of Tumor Cell Transplantation Possibilities ............................................................................. 307
21.6.3. Future Prospects for Precise Xenopus Gene Editing................................................................................. 308
Acknowledgments ................................................................................................................................................................ 308
References............................................................................................................................................................................ 309
21.1. HISTORICAL BACKGROUND
Pattengale and Leder, 1984). Cancer modeling in Xenopus
21.1.1. XENOPUS, FROM RESEARCH TOOL IN CELL AND
is a more recent development, especially aided with the
invention of genome engineering techniques such as zinc
DEVELOPMENTAL BIOLOGY TO GENETICALLY
fnger nucleases (ZFNs), transcription activator-like effecENGINEERED CANCER MODEL ORGANISM
tor nucleases (TALENs), and in particular CRISPR/Cas9
(Guo et al., 2014; Nakayama et al., 2014). As already extenThe frst reported experimental animal cancer model was
sively described in other chapters, Xenopus earned signif -
published at the beginning of the previous century by
cant credit for its valuable contributions to the exploration of
Yamagiwa and Ichikawa, in which the authors treated rabbit
early developmental processes and the molecular dissection
ears with coal tar, yielding the frst animal model for squaof developmental signaling pathways that, in the majority
mous cell carcinoma (1918). Since then, cancer modeling
of cases, appear to be highly conserved between frog and
using laboratory animals evolved as a tremendously broad
human. However, for studying human genetic diseases, mice
feld accompanied by an ever-evolving assortment of tools
and techniques that have aided the establishment and moni- and zebrafsh tend to be preferred by researchers as genetic
toring of these models. In 1988, the frst transgenic mouse vertebrate models. This is evidently because of the size of the
cancer model was patented, called “Oncomouse” by a group research feld, the many genetically mutant lines, transgenic
of Harvard researchers, based on their paper in which they reporter animals, standardized experimental protocols, and
generated mice expressing oncogenic fusion genes, result- (for the mouse) a wide range of verifed antibodies, as well as
ing in the induction of mammary adenocarcinomas (Stewart, well-established genomic data integration networks for these
DOI: 10.1201/9781003050230-24
301
21 Regulation in Xenopus
Dieter Tulkens and Kris Vleminckx
CONTENTS
21.1. Historical Background ............................................................................................................................................. 301
21.1.1. Xenopus, from Research Tool in Cell and Developmental Biology to Genetically
Engineered Cancer Model Organism ........................................................................................................ 301
21.1.2. A Diploid Genome Favors Genetic Research in Xenopus tropicalis ........................................................ 302
21.2. Past Observations ..................................................................................................................................................... 302
21.2.1. Early Xenopus Embryogenesis as a Source of Information for Studying Pathways
and Cellular Processes Involved in Cancer Initiation and Progression ..................................................... 302
21.2.2. Naturally Occurring Tumors in Xenopus .................................................................................................. 302
21.2.3. Induced Tumor–Like Structures................................................................................................................ 302
21.2.4. T umor–Immune System Interactions ........................................................................................................ 303
21.2.5. Genetically Engineered Xenopus Models ................................................................................................. 303
21.3. Challenges to Ov ercome .......................................................................................................................................... 303
21.4. Genetically Engineered Xenopus Models for Cancer Research .............................................................................. 303
21.4.1. Generation of Clinically Rele vant GEXMs .............................................................................................. 303
21.4.2. T ALEN-Mediated TSG Disruption as a First Genetic Xenopus tropicalis Cancer Model ...............................304
21.4.3. CRISPR/Cas9 Cancer Modeling in Xenopus tropicalis............................................................................ 305
21.5. Application Potential of Xenopus tropicalis Cancer Modeling................................................................................ 305
21.5.1. GEXM for Identifcation of No vel Tumor Dependencies ......................................................................... 305
21.5.2. GEXMs as Tool for Novel Anti-Cancer Compound Validation ................................................................ 306
21.6. Current and Future Xenopus tropicalis Cancer Modeling Methodologies .............................................................. 307
21.6.1. Tools for In Vivo Monitoring of Tumor Progression ................................................................................. 307
21.6.2. Ov erview of Tumor Cell Transplantation Possibilities ............................................................................. 307
21.6.3. Future Prospects for Precise Xenopus Gene Editing................................................................................. 308
Acknowledgments ................................................................................................................................................................ 308
References............................................................................................................................................................................ 309
21.1. HISTORICAL BACKGROUND
Pattengale and Leder, 1984). Cancer modeling in Xenopus
21.1.1. XENOPUS, FROM RESEARCH TOOL IN CELL AND
is a more recent development, especially aided with the
invention of genome engineering techniques such as zinc
DEVELOPMENTAL BIOLOGY TO GENETICALLY
fnger nucleases (ZFNs), transcription activator-like effecENGINEERED CANCER MODEL ORGANISM
tor nucleases (TALENs), and in particular CRISPR/Cas9
(Guo et al., 2014; Nakayama et al., 2014). As already extenThe frst reported experimental animal cancer model was
sively described in other chapters, Xenopus earned signif -
published at the beginning of the previous century by
cant credit for its valuable contributions to the exploration of
Yamagiwa and Ichikawa, in which the authors treated rabbit
early developmental processes and the molecular dissection
ears with coal tar, yielding the frst animal model for squaof developmental signaling pathways that, in the majority
mous cell carcinoma (1918). Since then, cancer modeling
of cases, appear to be highly conserved between frog and
using laboratory animals evolved as a tremendously broad
human. However, for studying human genetic diseases, mice
feld accompanied by an ever-evolving assortment of tools
and techniques that have aided the establishment and moni- and zebrafsh tend to be preferred by researchers as genetic
toring of these models. In 1988, the frst transgenic mouse vertebrate models. This is evidently because of the size of the
cancer model was patented, called “Oncomouse” by a group research feld, the many genetically mutant lines, transgenic
of Harvard researchers, based on their paper in which they reporter animals, standardized experimental protocols, and
generated mice expressing oncogenic fusion genes, result- (for the mouse) a wide range of verifed antibodies, as well as
ing in the induction of mammary adenocarcinomas (Stewart, well-established genomic data integration networks for these
DOI: 10.1201/9781003050230-24
301