Related Experiment Videos
C-myc deregulation during transformation induction: involvement of 7SK RNA
Abstract:
The process of oncogenic transformation has been widely studied but is still poorly understood. We have focused on the mechanism of deregulation of the c-myc gene during transformation of a temperature-sensitive SV40-transformed mouse cell line. Run-on transcription assays showed that the two c-myc minor promoters, P1 and P3, are transiently activated following induction of transformation and that peak activation of both promoters is preceded by a large increase in transcription of a small RNA (7SK). To test the possibility that this RNA might participate in promoter activation, we transfected cells with sense and antisense oligodeoxynucleotides corresponding to different regions of the 7SK RNA predicted to be accessible within the RNP particle. Out of 14 oligos tested, inhibition of activation of P1 and/or P3 was observed with four antisense oligonucleotides corresponding to looped regions in the putative 7SK secondary structure. To identify c-myc promoter sequences which might serve as targets for 7SK activity, we carried out mobility-shift assays with either whole or 7SK-depleted cell extracts. The CT element of the c-myc promoter formed a 7SK-dependent complex which could be competed only with the same antisense 7SK oligo that suppressed P1 and P3 activation in vivo. Taken together these results suggest that 7SK RNP participates in transformation-dependent c-myc deregulation.
Insights
A small RNA (7SK) and its ribonucleoprotein particle (RNP) complex are involved in activating c-myc gene promoters during oncogenic transformation. This suggests 7SK RNP plays a role in c-myc gene deregulation in cancer development.
Area of Science:
- Molecular Biology
- Cancer Research
- Gene Regulation
Background:
- Oncogenic transformation is a complex process, with mechanisms of c-myc gene deregulation being poorly understood.
- The c-myc gene is frequently dysregulated in various cancers.
Purpose of the Study:
- To investigate the role of a small RNA (7SK) in the deregulation of the c-myc gene during oncogenic transformation.
- To identify the specific mechanisms by which 7SK RNA influences c-myc promoter activity.
Main Methods:
- Utilized run-on transcription assays to measure c-myc promoter activity.
- Employed antisense oligodeoxynucleotides to inhibit 7SK RNA function.
- Performed mobility-shift assays to identify interactions between 7SK RNP and c-myc promoter elements.
Main Results:
- Transient activation of c-myc promoters (P1 and P3) was observed upon transformation induction, preceded by increased 7SK RNA transcription.
- Specific antisense oligonucleotides targeting 7SK RNA inhibited c-myc promoter activation.
- The CT element of the c-myc promoter formed a 7SK-dependent complex.
Conclusions:
- 7SK ribonucleoprotein particle (RNP) participates in the transformation-dependent deregulation of the c-myc gene.
- This finding provides new insights into the regulatory mechanisms of c-myc in cancer.