Induction of tumorigenesis and metastasis by the murine orthologue of tumor protein D52.
Expression studies have consistently identified tumor protein D52 (TPD52) overexpression in tumor cells. Murine TPD52 (mD52) shares 86% identity with the human orthologue. To study a possible role for TPD52 in transformation, 3T3 fibroblasts were transfected with the full-length cDNA for mD52. Expression of mD52 was confirmed by reverse transcription-PCR (RT-PCR), real-time PCR, and Western blot analysis compared with 3T3 and vector-transfected 3T3 (3T3.V), and the resultant cell line was designated 3T3.mD52. At 4 weeks, 3T3.mD52 gained a 2-fold increase in growth rate, lost contact inhibition, and exhibited a marked phenotype change. Further characterization revealed an acquired ability for anchorage-independent cell growth. To determine whether 3T3.mD52 had become tumorigenic, naïve, healthy, immunocompetent syngeneic mice were inoculated subcutaneously with varying cell doses. Tumors measuring >1 cm(2) were detected 60 days postinoculation with 3T3.mD52, and a 50% subcutaneous tumor incidence was obtained with as few as 5 x 10(5) 3T3.mD52 cells. Remarkably, when lungs from 3T3.mD52 tumor-bearing mice were analyzed, numerous tumor nodules were observed, ranging from nodules less than 10 to nodules too numerous to count (inoculation with 1 x 10(5) and 5 x 10(6) cells, respectively). Further support for the metastatic capacity of 3T3.mD52 was the demonstration that transforming growth factor (TGF)-betaR1 (receptor) expression decreased and TGF-beta1 secretion increased in 3T3.mD52 compared with 3T3 controls. cDNA microarray analysis showed a gene expression pattern that further supported mD52-induced transformation and metastasis. Together, these data suggest that mD52 expression in 3T3 cells initiated cellular transformation, tumorigenesis, and progression to metastasis.
Lewis
Jennifer D
JD
Department of Microbiology and Immunology, Texas Tech University Health Sciences Center, 3601 4th Street, MS 6591, Lubbock, TX 79430, USA.
Payton
Laura A
LA
Whitford
Jill G
JG
Byrne
Jennifer A
JA
Smith
David I
DI
Yang
Libang
L
Bright
Robert K
RK
D000818:Animals; D049109:Cell Proliferation; D002471:Cell Transformation, Neoplastic / Q000378:metabolism*; D005260:Female; D008175:Lung Neoplasms / Q000556:secondary*; D051379:Mice; D008807:Mice, Inbred BALB C; D041681:NIH 3T3 Cells; D009363:Neoplasm Proteins / Q000378:metabolism*; D014162:Transfection; D053773:Transforming Growth Factor beta1 / Q000378:metabolism; D023041:Xenograft Model Antitumor Assays
D009363:Neoplasm Proteins; C486415:Tpd52 protein, mouse; D053773:Transforming Growth Factor beta1