Related Experiment Videos
Retinoic acid down-regulates the expression of the vasoactive intestinal polypeptide receptor type-1 in human breast
1Department of Clinical Biochemistry, Bispebjerg University Hospital, Copenhagen, Denmark. BMA@biobase.dk
Abstract:
Four breast carcinoma cell lines (T47D, ZR-75-1, MDA-MB-231, and MCF-7) were tested for regulation of the expression of vasoactive intestinal polypeptide receptor type-1 (VIP-R1). In all four cell lines, retinoic acid (RA) treatment caused a fast and marked decrease in VIP-R1 mRNA level as examined by Northern blots. Cycloheximide pretreatment attenuated the effect from 3- to 2-fold, indicating that existing proteins can mediate the decreasing effect of RA, but to attain the maximal effect new protein synthesis might be needed. Transcriptional inhibition with Actinomyocin D showed that RA did not influence the VIP-R1 mRNA half-life, indicating that the decreasing effect of RA on the mRNA level is due to transcriptional inhibition. In agreement with the observations on mRNA level, we found that the VIP receptor number was reduced 3-fold from 88 to 32 fmol/10(6) cells in T47D cells and from 222 to 73 fmol/10(6) cells in MDA-MB-231 cells upon RA treatment for 72 h. The promoter and 5'-flanking region of the VIP-R1 gene were cloned from a human placental cosmid library, and 2.5 kb were sequenced to search for regulatory elements. Our results, therefore, imply that the regulation of VIP-R1 gene expression by RA could have a role in human mammary tumor biology.
Insights
Retinoic acid (RA) significantly reduces vasoactive intestinal polypeptide receptor type-1 (VIP-R1) mRNA and protein levels in breast cancer cells. This regulation occurs transcriptionally, suggesting a role in mammary tumor biology.
Area of Science:
- Molecular Biology
- Cell Biology
- Oncology
Background:
- Vasoactive intestinal polypeptide receptor type-1 (VIP-R1) is implicated in cell proliferation and survival.
- Understanding the regulation of VIP-R1 expression is crucial for exploring therapeutic strategies in breast cancer.
Purpose of the Study:
- To investigate the effect of retinoic acid (RA) on VIP-R1 gene expression in human breast carcinoma cell lines.
- To elucidate the mechanism by which RA regulates VIP-R1 expression.
Main Methods:
- Northern blot analysis to assess VIP-R1 mRNA levels.
- Treatment with cycloheximide and Actinomycin D to determine the role of protein synthesis and transcription.
- Measurement of VIP receptor binding capacity.
- Cloning and sequencing of the VIP-R1 gene promoter and 5'-flanking region.
Main Results:
- RA treatment markedly decreased VIP-R1 mRNA levels in all four breast carcinoma cell lines.
- RA's effect on mRNA levels is primarily due to transcriptional inhibition, not altered mRNA half-life.
- VIP receptor number was significantly reduced upon RA treatment in T47D and MDA-MB-231 cells.
- Analysis of the VIP-R1 gene's regulatory regions was initiated.
Conclusions:
- Retinoic acid transcriptionally downregulates VIP-R1 gene expression in breast cancer cells.
- The findings suggest a potential role for RA-mediated regulation of VIP-R1 in human mammary tumor biology.