Induction of cisplatinum sensitivity without alteration in radiation sensitivity by fractionated radiation treatment of a human laryngeal squamous cell carcinoma cell line

Purpose : To determine if fractionated radiation treatment can alter cisplatinum sensitivity of a human laryngeal squamous carcinoma cell line. Methods and Materials : Human squamous carcinoma cells, both previously untreated, as well as survivors of fractionated radiation therapy, were tested in vitro for their sensitivity to gamma radiation and cisplatinum. Fractionated gamma radiation was delivered in 14 or 10 daily fractions of 2 Gy. The cell line, cSCC-20, was derived from an untreated primary human laryngeal carcinoma. Results : The human laryngeal squamous cell carcinoma cell line, cSCC-20, was demonstrated to have heterogeneous subpopulations with respect to cisplatinum sensitivity. No variation in radiation sensitivity was seen among subpopulations of varying cisplatinum sensitivity. The cells were relatively radioresistant (Do = 2.5 Gy). Fractionated radiation treatments of the parent cell line (14 fractions, 14 days, 2 Gy/fraction) or a cisplatinum sensitive subline (10 fractions, 12 days, 2 Gy/fraction) induced cisplatinum sensitivity (factor of 1.3 to 1.4) in the surviving cells. Conclusion : Fractionated radiation treatment of human squamous carcinoma cells in vitro induced sensitivity to cisplatinum without concomitant alteration in radiation sensitivity.