Nucleotide sequence analysis of c-raf-1 cDNA and promoter from a radiation-resistant human squamous carcinoma cell line: Deletion within exon 17
✍ Scribed by Bharvin K. R. Patel; Usha Kasid
- Publisher
- John Wiley and Sons
- Year
- 1993
- Tongue
- English
- Weight
- 517 KB
- Volume
- 8
- Category
- Article
- ISSN
- 0899-1987
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
The c‐raf‐1 proto‐oncogene is the cellular homologue of v‐raf, the oncogene of the acutely transforming retrovirus 3611‐MSV. The product of c‐raf‐1 (raf‐1) is a 74‐kDa cytoplasmic serine/threonine protein kinase. We previously reported that antisense human c‐raf‐1 cDNA transfection results in reduction of the endogenous c‐raf‐1 transcript, decreased tumor growth rate, and enhanced radiation sensitivity of SQ‐20B tumor cells established from a radiation‐resistant laryngeal squamous cell carcinoma. In the study reported here, we used cDNA‐linked polymerase chain reaction amplification and nucleotide sequencing to examine the structure of the 3233‐bp SQ‐20B c‐raf‐1 cDNA. The 812‐bp c‐raf‐1 promoter region was analyzed by genomic DNA amplification followed by cloning and sequencing. Sequence comparison with a previously published c‐raf‐1 sequence indicated no structural changes within the coding region of SQ‐20B c‐raf‐1. However, a 4‐bp deletion was observed in the 3′ untranslated region within exon 17. This deletion was also present in a c‐raf‐1 cDNA clone isolated from a SQ‐20B cDNA library. While the possibility of a 3′ transcriptional control mechanism cannot be ruled out, it appears that the raf‐1 protein kinase may regulate the development of radioresistant malignancies via interaction with other molecules in the damage and repair—related signal transduction pathways. © 1993 Wiley‐Liss, Inc.