Concerted functions of HDAC1 and microRNA-574-5p repress alternatively spliced ceramide synthase 1 expression in human cancer cells.
Bottom Line: Moreover, an alternatively spliced variant CerS1 mRNA (CerS1-2) was detected mainly in cancer cells or primary tumour tissues compared to controls, which was targeted by miR-574-5p for degradation.A specific 3'UTR-targeting site, localized within the retained intron between exons 6 and 7, was identified, and its mutation, or miR-574-5p knockdown prevented the degradation of CerS1-2 mRNA.Accordingly, knockdown of CerS1 partially protected cancer cells from MS-275/miR-574-5p siRNA-mediated growth inhibition.
Affiliation: Department of Biochemistry and Molecular Biology, Medical University of South Carolina, SC, USA.Show MeSH
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Mentions: To determine whether down-regulation of CerS1 mRNA in the majority of HNSCC tumour tissues compared to their adjacent normal head and neck tissues (Karahatay et al, 2007; Koybasi et al, 2004) is also consistent in cell culture conditions, we measured CerS1 and CerS6 mRNA in multiple human cancer cells (UM-SCC-22A, UM-SCC-14A and UM-SCC-1) compared to non-cancerous keratinocytes using quantitative-polymerase chain reaction (Q-PCR). Consistent with HNSCC primary tumours, CerS1 was down-regulated about 10–20-fold in HNSCC cell lines compared to normal human epidermal primary keratinocytes (NHEK) or HPV-E6/E7-immortalized human keratinocytes controls (Fig 1A and B). CerS6 mRNA was similar in HNSCC cell lines and immortalized keratinocytes (Fig 1B). Down-regulation of CerS1 was also associated with lower C18-ceramide, measured with liquid chromatography/mass spectrometry (LC/MS/MS), in UM-SCC-1 and -22A (Fig 1C) compared to immortalized keratinocytes (about 90 and 50%, respectively). Thus, these studies indicate that CerS1/C18-ceramide, but not CerS6/C16-ceramide is down-regulated in HNSCC cancer cell lines compared to non-cancerous keratinocytes, consistent with decreased CerS1/C18-ceramide in HNSCC tumour compared to non-cancerous head and neck tissues (Karahatay et al, 2007; Koybasi et al, 2004).
Affiliation: Department of Biochemistry and Molecular Biology, Medical University of South Carolina, SC, USA.