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Altered RNA transport without derepression in a rat kidney tumor induced by dimethylnitrosamine
Abstract:
RNA/DNA hybridization in the presence of competing RNA was used to study transcription and transport of RNA from the nucleus to the cytoplasm in a rat renal tumor induced by a single intraperitoneal injection of dimethylnitrosamine (DMN). Neither repression nor derepression of transcription of repetitive DNA can be detected in this tumor, but transcripts of all active families of such sequences are found in the tumor cytoplasm. This is the pattern of RNA change found in the chemically-induced hepatocellular carcinomas and contrasts with the pattern of virus-induced renal tumors in which both altered transport and derepression of host repetitive sequences have been demonstrated. The alteration of RNA transport is nearly complete in the kidney only two days after the above treatment, but there is no such alteration detectable in the kidney after nine days of feeding a liver carcinogen which is not carcinogenic to kidneys. This data supports the significance and specificity of the loss of ability to restrict certain RNA sequences to the nucleus early during malignant transformation.
Insights
Dimethylnitrosamine (DMN) induces tumors with altered RNA transport, not transcription changes. This loss of nuclear RNA restriction is specific to early malignant transformation.
Area of Science:
- Molecular Biology
- Oncology
- Biochemistry
Background:
- Studying RNA processing and transport is crucial for understanding gene regulation.
- Malignant transformation can involve alterations in RNA metabolism.
- Dimethylnitrosamine (DMN) is a chemical carcinogen used to induce experimental tumors.
Purpose of the Study:
- To investigate RNA transcription and nucleocytoplasmic transport in a rat renal tumor model induced by DMN.
- To compare RNA changes in chemically induced tumors with those in virus-induced tumors.
- To determine the specificity and timing of RNA transport alterations during carcinogenesis.
Main Methods:
- RNA/DNA hybridization techniques were employed.
- Analysis of RNA transcription and transport from nucleus to cytoplasm.
- Comparison of RNA patterns in DMN-induced renal tumors, hepatocellular carcinomas, and virus-induced renal tumors.
Main Results:
- DMN-induced renal tumors showed no significant changes in repetitive DNA transcription.
- Transcripts of active repetitive DNA sequences were found in the cytoplasm of tumor cells.
- Altered RNA transport, but not transcriptional derepression, characterized these tumors, contrasting with virus-induced tumors.
Conclusions:
- The study highlights a specific loss of nuclear RNA restriction early in malignant transformation.
- Altered nucleocytoplasmic RNA transport is a key feature of DMN-induced renal tumors.
- These findings underscore the significance of RNA transport regulation in cancer development.