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Updated: Jan 20, 2026
High-throughput Screening for Chemical Modulators of Post-transcriptionally Regulated Genes
Published on: March 3, 2015
Consulting prostate cancer cohort data uncovers transcriptional control: Regulation of the MARCH6 gene
Hudson W Coates1, Ngee Kiat Chua1, Andrew J Brown1
1School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, Australia.
Abstract:
Cholesterol accumulation is a hallmark of prostate cancer (PCa) enabled by the upregulation of its synthesis, which presents a potential therapeutic target. This pathway is suppressed by the E3 ubiquitin ligase membrane-associated RING-CH-type finger 6 (MARCH6); however, little is known of MARCH6 regulation, particularly at the transcriptional level. Here, we consulted large transcriptomic PCa datasets to investigate transcription factors and DNA sequence elements that regulate the MARCH6 gene. Amongst 498 primary PCa tissues of The Cancer Genome Atlas, we identified a striking positive correlation between MARCH6 and androgen receptor (AR) gene expression (r = 0.81, p < 1 × 10-117) that held in other primary tumour datasets. Two putative androgen response elements were identified in the MARCH6 gene using motif prediction and mining of publicly accessible chromatin immunoprecipitation-sequencing data. However, MARCH6 expression was not androgen-responsive in luciferase reporter and qRT-PCR assays. Instead, we established that the MARCH6-AR correlation in primary PCa is due to common regulation by the transcription factor Sp1. We located a region 100 bp downstream of the MARCH6 transcriptional start site that contains three Sp1 binding sites and strongly upregulates promoter activity. The functionality of this region, and Sp1-mediated upregulation of MARCH6, was confirmed using pharmacological and genetic inhibition of Sp1. Moreover, modulation of Sp1 activity affected the stability of squalene monooxygenase, a cholesterol biosynthesis enzyme and MARCH6 substrate. We thus establish Sp1 as the first known regulator of the MARCH6 gene and demonstrate that interrogation of transcriptomic datasets can assist in the de novo inference of transcriptional regulation.
Insights
Sp1 is identified as the first regulator of the membrane-associated RING-CH-type finger 6 (MARCH6) gene, impacting cholesterol synthesis in prostate cancer (PCa). This finding offers new therapeutic targets for PCa by modulating Sp1 activity and MARCH6 expression.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Cholesterol accumulation is a key feature of prostate cancer (PCa), with its synthesis pathway being a potential therapeutic target.
- The E3 ubiquitin ligase membrane-associated RING-CH-type finger 6 (MARCH6) suppresses this pathway, but its transcriptional regulation remains largely unknown.
Purpose of the Study:
- To investigate the transcriptional factors and DNA elements regulating the MARCH6 gene in prostate cancer.
- To identify the upstream regulators of MARCH6 and understand its role in PCa pathogenesis.
Main Methods:
- Analysis of large transcriptomic PCa datasets (The Cancer Genome Atlas).
- Motif prediction and chromatin immunoprecipitation-sequencing data mining to identify potential regulatory elements.
- Luciferase reporter assays, qRT-PCR, and pharmacological/genetic inhibition to validate Sp1's role.
- Assessment of Sp1's effect on squalene monooxygenase stability.
Main Results:
- A strong positive correlation was found between MARCH6 and androgen receptor (AR) gene expression in PCa tissues.
- Contrary to initial hypotheses, MARCH6 expression was not directly androgen-responsive.
- The transcription factor Sp1 was identified as the common regulator of MARCH6 and AR expression.
- A specific region downstream of the MARCH6 transcriptional start site with Sp1 binding sites was found to upregulate promoter activity.
- Sp1 inhibition reduced MARCH6 expression and affected the stability of squalene monooxygenase, a MARCH6 substrate.
Conclusions:
- Sp1 is the first identified transcriptional regulator of the MARCH6 gene.
- Sp1 plays a crucial role in regulating MARCH6 expression and, consequently, cholesterol biosynthesis in prostate cancer.
- Transcriptomic dataset analysis is a valuable tool for inferring novel transcriptional regulatory mechanisms.
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