Radiosensitivity of small-cell lung cancer xenografts compared with activity of c-myc, N-myc, L-myc, c-raf-1 and K-ras proto-oncogenes
✍ Scribed by Kåre Rygaard; Robert J. C. Slebos; Mogens Spang-Thomsen
- Publisher
- John Wiley and Sons
- Year
- 1991
- Tongue
- French
- Weight
- 687 KB
- Volume
- 49
- Category
- Article
- ISSN
- 0020-7136
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
Oncogenes of the myc family c‐raf‐I and K‐ras have been reported to modulate radiosensitivity. We examined the possible relationship between in vivo radiosensitivity to single‐dose irradiation with 3‐10 Gy, and activity of these proto‐oncogenes in 2 sets of small‐cell lung cancer (SCLC) xenografts, the CPH and the GLC series. CPH‐54A and CPH‐54B are in vitro‐derived subclones of a SCLC cell line, while the GLC tumours were established as cell lines from a patient during longitudinal follow‐up. Both tumours were later transferred into nude mice. CPH‐54A was more sensitive to single‐dose irradiation than CPH‐54B, while, with respect to the 3 GLC tumours examined, GLC‐16 was most sensitive, followed by GLC‐14 and GLC‐19. The CPH tumours expressed similar amounts of c‐myc and c‐raf‐I mRNA, and neither expressed N‐myc or L‐myc. GLC‐14 expressed N‐myc and c‐raf‐I mRNA but no c‐myc. GLC‐16 and GLC‐19 expressed identical amounts of c‐raf‐I and high levels of c‐myc mRNA, but neither expressed N‐myc or L‐myc. None of the tumours was mutated at codon 12 of K‐ras. Our results show that SCLC xenografts with different radiosensitivity may express identical amounts of some of the proto‐oncogenes reported to modulate radiosensitivity. Thus, factors other than activation of the examined proto‐oncogenes must be involved in causing the differences in radiosensitivity found in the SCLC xenografts. Possible long‐term effects of irradiation on proto‐oncogene expression was examined in xenografts of GLC‐16, following regrowth after single‐dose irradiation. No long‐term difference in expression of c‐raf‐I or c‐myc mRNA was detected between control tumours and tumours irradiated with 5 or 10 Gy.