Related Experiment Video

Updated: Aug 21, 2026

Monitoring Protein-RNA Interaction Dynamics In Vivo at High Temporal Resolution Using χCRAC
09:15

Monitoring Protein-RNA Interaction Dynamics In Vivo at High Temporal Resolution Using χCRAC

Published on: May 9, 2020

Regulation of RARbeta1 expression in head and neck cancer cells by cell density-dependent chromatin remodeling

Emile M Youssef1, Jean-Pierre J Issa, Reuben Lotan

  • 1Department of Leukemia, The University of Texas M. D. Anderson Cancer Center, Houston, Texas, USA. eyoussef@mdanderson.org

Cancer Biology & Therapy
|October 7, 2004
PubMed

Insights

Retinoid signaling impacts cancer. Researchers found that retinoic acid receptor beta 1 (RARbeta1) expression increases with cell density in head and neck cancer cells, regulated by histone acetylation.

Area of Science:

  • Molecular biology
  • Cancer research
  • Epigenetics

Background:

  • Retinoids are crucial in cancer therapy, acting via nuclear receptors like retinoic acid receptors (RARs).
  • Human RARbeta has isoforms RARbeta1, RARbeta2, and RARbeta4, with RARbeta2 being tumor-suppressive and RARbeta1 linked to carcinogenesis.
  • Factors regulating RARbeta1 expression remain unclear.

Purpose of the Study:

  • To investigate the factors regulating the expression of the RARbeta1 isoform in head and neck squamous cell carcinoma.
  • To explore the epigenetic mechanisms controlling RARbeta1 expression in response to cellular conditions.

Main Methods:

  • Utilized real-time reverse-transcriptase polymerase chain reaction to quantify RARbeta isoform expression.
  • Employed combined bisulfite restriction analysis and chromatin immunoprecipitation assays to assess epigenetic modifications.
  • Cultured head and neck squamous cell carcinoma cells at varying densities and durations.

Main Results:

  • RARbeta1 expression significantly increased in UMSCC38 cells with higher cell density and longer culture duration.
  • This increase was not attributed to promoter demethylation.
  • Higher cell densities correlated with increased histone 3 acetylation at lysine 9 specifically in RARbeta1, not RARbeta2.

Conclusions:

  • Cell density is a key regulator of RARbeta1 expression in head and neck squamous cell carcinoma.
  • Histone acetylation, specifically H3K9 acetylation, mediates the cell density-dependent regulation of RARbeta1.
  • Understanding RARbeta1 regulation offers insights into retinoid signaling in cancer development.

More Related Videos

Identification of Transcription Factor Regulators using Medium-Throughput Screening of Arrayed Libraries and a Dual-Luciferase-Based Reporter11:32

Identification of Transcription Factor Regulators using Medium-Throughput Screening of Arrayed Libraries and a Dual-Luciferase-Based Reporter

Published on: March 27, 2020

Related Concept Videos

Chromatin Position Affects Gene Expression02:35

Chromatin Position Affects Gene Expression

Chromatin is the massive complex of DNA and proteins packaged inside the nucleus. The complexity of chromatin folding and how it is packaged inside the nucleus greatly influences  access to genetic information. Generally, the nucleus' periphery is considered transcriptionally repressive, while the cell's interior is considered a transcriptionally active area. 
Topologically Associated Domains (TADs)
The 3-dimensional positioning of chromatin in the nucleus influences the timing and level of...
Chromatin Structure Regulates pre-mRNA Processing02:41

Chromatin Structure Regulates pre-mRNA Processing

In eukaryotic cells, nascent mRNA transcripts need to undergo many post-transcriptional modifications to reach the cell cytoplasm and translate into functional proteins. For a long time, transcription and pre-mRNA processing were considered two independent events that occur sequentially in the cell. However, it has now been well established that transcription and pre-mRNA processing are two simultaneous processes that are precisely regulated inside the cell.
The chromatin structure, especially...
Negative Regulator Molecules01:23

Negative Regulator Molecules

Positive regulators allow a cell to advance through cell cycle checkpoints. Negative regulators have an equally important role as they terminate a cell’s progression through the cell cycle—or pause it—until the cell meets specific criteria.
Regulation of Nuclear Protein Sorting01:45

Regulation of Nuclear Protein Sorting

Nuclear protein sorting regulates nucleus composition and gene expression, crucial for determining the fate of a eukaryotic cell. Hence, the entry and exit of molecules across the nuclear envelope is a tightly controlled process. Nuclear protein sorting can be inhibited by one of the following ways: 1) masking cargo signal sequences, 2) modifying the nuclear receptor's affinity for cargo, 3) controlling the nuclear pore size, 4) retaining the cargo during its transit to the cytosol or the...
RNA Polymerase II Accessory Proteins02:36

RNA Polymerase II Accessory Proteins

Proteins that regulate transcription can do so either via direct contact with RNA Polymerase or through indirect interactions facilitated by adaptors, mediators, histone-modifying proteins, and nucleosome remodelers. Direct interactions to activate transcription is seen in bacteria as well as in some eukaryotic genes. In these cases, upstream activation sequences are adjacent to the promoters, and the activator proteins interact directly with the transcriptional machinery. For example, in...
Spreading of Chromatin Modifications02:25

Spreading of Chromatin Modifications

The histone proteins in the nucleosomes are post-translationally modified (PTM) to increase or decrease access to DNA. The commonly observed PTMs are methylation, acetylation, phosphorylation, and ubiquitination of lysine amino acids in the histone H3 tail region. These histone modifications have specific meaning for the cell. Hence, they are called "histone code". The protein complex involved in histone modification is termed as "reader-writer" complex.
Writers
The writer is an enzyme that can...