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Transforming genes in human tumors
Abstract:
DNAs isolated from a variety of human tumor cell lines as well as from naturally occurring human carcinomas and sarcomas were shown to induce morphologic transformation upon transfection into NIH/3T3 cells. All tested transformants contained human DNA sequences, some of which specifically cosegregated with the malignant phenotype in additional cycles of transfection. Southern blot analysis of second cycle transformants derived from T24 human bladder carcinoma cells showed the presence of a single 15 kbp EcoRI fragment of human DNA. These sequences were molecularly cloned utilizing lambda Charon 9A as the cloning vector. The resulting recombinant DNA molecule, designated lambda T24-15A, was shown to contain an internal 6.6 kbp Bam HI fragment of human DNA that transformed NIH/3T3 fibroblasts with a specific activity of 5 X 10(4) focus forming units per picomole. These results indicate that we have molecularly cloned an oncogene present in T24 bladder carcinoma cells. Comparison of molecular clones containing the T24 oncogene and its normal homologue did not reveal biochemical differences that helped to explain the malignant properties of this oncogene. Finally, we report preliminary results indicating that the T24 bladder carcinoma oncogene is highly related to the transforming gene of BALB-MSV, an acute transforming retrovirus.
Insights
Researchers identified and cloned a specific oncogene from T24 bladder carcinoma cells. This oncogene induced malignant transformation in NIH/3T3 cells, suggesting its role in cancer development.
Area of Science:
- Molecular Biology
- Oncology
- Genetics
Background:
- Human tumor DNA can induce cellular transformation.
- Identifying specific oncogenes is crucial for understanding cancer.
- The T24 bladder carcinoma cell line is a model for studying oncogenesis.
Purpose of the Study:
- To isolate and characterize the oncogene responsible for malignant transformation in T24 bladder carcinoma cells.
- To investigate the transforming potential of cloned human DNA sequences.
- To compare the cloned oncogene with its normal counterpart.
Main Methods:
- DNA transfection into NIH/3T3 cells.
- Southern blot analysis to identify human DNA sequences in transformants.
- Molecular cloning using lambda Charon 9A.
- Focus-forming assays to determine transforming activity.
Main Results:
- DNA from human tumors induced morphologic transformation in NIH/3T3 cells.
- A specific 6.6 kbp Bam HI fragment from T24 cells, cloned as lambda T24-15A, exhibited potent transforming activity.
- The cloned oncogene showed high relatedness to the transforming gene of BALB-MSV.
- No significant biochemical differences were found between the oncogene and its normal homologue.
Conclusions:
- A specific oncogene from T24 bladder carcinoma cells has been molecularly cloned.
- This oncogene possesses the ability to induce malignant transformation.
- The cloned oncogene is evolutionarily related to other known viral transforming genes.
- Further research is needed to elucidate the biochemical basis of its malignant properties.