Korean J Dermatol.  2014 Oct;52(10):692-700.

The Role of ATF3 Expression and Calcineurin Inhibition in the Putative Cancer Stem Cell Fraction of Human Cutaneous Squamous Cell Carcinoma

• Chung BY
• Kim BW
• Lee MW
• Choi JH
• Kim CD
• Chang SE

Abstract

BACKGROUND
A previous study reported that calcineurin inhibition by cyclosporin A (CsA) showed tumor-enhancing effects through the induction of the ATF3 transcription factor and the associated suppression of p53. The development and aggressiveness of cutaneous squamous cell carcinoma (SCC) may be determined by cancer stem cell populations, which have self-renewing potential.
OBJECTIVE
To determine the role of ATF3 and calcineurin inhibition in the proliferation of SCC and evaluate the existence of putative SCC stem cells.
METHODS
We performed real-time PCR, fluorescence activated cell sorting, and clonogenicity assays in SCC13 cells under conditions of calcineurin inhibition by CsA or ATF3 and p53 overexpression. The relationships amongst calcineurin inhibition, p53, and ATF3 were demonstrated by western blot analysis and transient transfection assays in SCC13 cells.
RESULTS
In putative stem cell populations of SCC13 cells enriched in self-renewal potential, p53 expression was lower than that in differentiated SCC13 cells. CsA treatment or ATF3 overexpression caused an expansion of stem cell populations. Additionally, p53 overexpression inhibited cellular proliferation and reduced clonogenicity in SCC13 cells. CsA treatment led to a decrease in p53 expression and an increase in ATF3 in SCC13 cells on western blots. SCC13 cells with CsA and small interfering RNA against ATF3 demonstrated lower cell viability than SCC13 cells with CsA only and SCC13 cells with CsA and small interfering control RNA after 14 days.
CONCLUSION
Putative cancer stem cell populations and differentiated cell populations in SCCs are positively regulated by ATF3 and p53, respectively.

Keyword

Activating transcription factor 3; Neoplastic stem cell; Calcineurin; p53; Squamous cell carcinoma

MeSH Terms

Activating Transcription Factor 3
Blotting, Western
Calcineurin*
Carcinoma, Squamous Cell*
Cell Proliferation
Cell Survival
Cyclosporine
Flow Cytometry
Humans
Neoplastic Stem Cells*
Real-Time Polymerase Chain Reaction
RNA
RNA, Small Interfering
Stem Cells
Transfection
Activating Transcription Factor 3
Calcineurin
Cyclosporine
RNA
RNA, Small Interfering