Ceramide synthase 6 knockdown suppresses apoptosis after photodynamic therapy in human head and neck squamous carcinoma cells.

Abstract

BACKGROUND:

The effectiveness of photodynamic therapy (PDT) for cancer treatment correlates with apoptosis. We observed that suppression of de novo-generated sphingolipids, e.g. ceramide, renders cells resistant to apoptosis post-PDT. Ceramide synthase 6 (CerS6) has been implicated in apoptosis after various stimuli.

AIM:

To investigate the involvement of down-regulation of CerS6 in apoptosis and its impact on the sphingolipid profile post-PDT with the silicone phthalocyanine Pc 4 in a human head and neck squamous carcinoma cell line.

MATERIALS AND METHODS:

Besides siRNA transfections and PDT treatment, immunoblotting for protein expression, mass spectrometry for sphingolipid analysis, spectroflurometry and flow cytometry for apoptotic marker detection, and trypan blue assay for cytotoxicity assessment, were used.

RESULTS:

CerS6 knockdown led to reduction in PDT-induced DEVDase activation, mitochondrial depolarization, apoptosis and cell death. CerS6 knockdown was associated with selective decreases in ceramides and dihydroceramides, markedly of C18-dihydroceramide, post-PDT.

CONCLUSION:

CerS6 might be a novel therapeutic target for regulating apoptotic resistance to PDT.

• Authors: Duska Separovic, Paul Breen, Nicholas Joseph, Jacek Bielawski, Jason S Pierce, Eric VAN Buren, Tatyana I Gudz
• Journal: Anticancer research (Anticancer Res) Vol. 32 Issue 3 Pg. 753-60 (Mar 2012) ISSN: 1791-7530 [Electronic] Greece
• PMID: 22399588 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, U.S. Gov't, Non-P.H.S.)

Chemical References

• DNA Primers
• Membrane Proteins
• CERS6 protein, human
• Sphingosine N-Acyltransferase

Topics

• Base Sequence
• Carcinoma, Squamous Cell (drug therapy, enzymology, pathology)
• DNA Primers
• Gene Knockdown Techniques
• Head and Neck Neoplasms (drug therapy, enzymology, pathology)
• Humans
• Membrane Proteins (genetics, metabolism)
• Photochemotherapy
• Sphingosine N-Acyltransferase (genetics, metabolism)