Activation of putative transposition intermediate formation in tumor cells

Area of Science:

• Molecular Biology
• Genomics
• Cancer Research

Background:

• Mobile genetic elements, including intracisternal A particle (IAP) genes and B2 sequences, are integral components of the mouse genome.
• Understanding the transcriptional activity of these elements in various cellular contexts is crucial for deciphering their role in biological processes.

Purpose of the Study:

• To investigate and compare the transcription levels of IAP genes and B2 sequences in different mouse tumor cells versus normal tissues.
• To explore the potential correlation between the activity of these mobile elements and tumor progression.

Main Methods:

• Analysis of poly(A)+ RNA from tumor cells and normal tissues using Northern blot hybridization.
• Hybridization probes derived from cloned IAP genes and B2 sequences.
• Cloning of free closed circular DNAs hybridizing to IAP gene probes from Ehrlich ascites carcinoma cells.

Main Results:

• Significantly elevated transcription levels (10- to 100-fold increase) of IAP gene transcripts were observed in tumor cells compared to normal cells.
• Predominant IAP-gene specific RNAs of 9.5, 6.8, and 5.3 kb were identified in all tested tumor cells, with additional species in some tumors.
• Active synthesis of small cytoplasmic B2 RNA, transcribed by RNA polymerase III, was detected at higher levels in most tumor cells than in normal cells.

Conclusions:

• The data indicate a marked enhancement in the transcription of mobile elements, specifically IAP genes and B2 sequences, within tumor cells.
• This heightened activity suggests that enhanced transposition of mobile elements could be a significant contributing factor to tumor development and progression.