Heart and bone tumors in transgenic mice

Area of Science:

• Oncology
• Genetics
• Molecular Biology

Background:

• Tissue-specific cancer development can be induced in mice using simian virus 40 (SV40) large tumor (T) antigen.
• Investigating oncogene susceptibility in specific cell types is crucial for understanding cancer mechanisms.

Purpose of the Study:

• To assess the neoplastic transformation potential of SV40 T-antigen in haploid round spermatids.
• To generate and characterize transgenic mouse models for studying tissue-specific oncogenesis.

Main Methods:

• Generation of transgenic mice harboring a chimeric gene (SV40 T-antigen linked to mouse protamine 1 gene regulatory sequences).
• Analysis of transgene expression patterns in various tissues, including testes, heart, and temporal bone.
• Histopathological examination and immunostaining for T-antigen in tumor tissues and testes.

Main Results:

• The transgene was expressed in round spermatids, heart, and temporal bone.
• Unexpectedly, cardiac rhabdomyosarcomas (right atrium) and bilateral temporal bone osteosarcomas developed.
• No testicular pathology was observed, and T-antigen was not detected in testicular tissue.
• SV40 transcripts showed differential processing in testis versus tumor tissues.

Conclusions:

• Round spermatids are surprisingly resistant to neoplastic transformation by SV40 T-antigen, despite transgene expression.
• Transgenic mice develop specific tumors in the heart and temporal bone, offering models for cardiac and bone neoplasia research.
• Established transgenic lines provide a valuable resource for studying cardiac and bone physiology and cancer development.