Use of the protein kinase C inhibitor H-7, l-(5-isoquinolinylsulfonyl)-2-methylpiperazine, as a radiosensitizer in HeLa cells

The isoquinoline sulfonamide H‐7 has been shown to delay the onset of radiation‐induced G2 arrest suggesting its possible application as a radiosensitizer. The effectiveness of H‐7 as a radiosensitizer and its toxicity in HeLa cells were evaluated. Cells were treated with either 10 or 100 μmM H‐7 and exposed to gamma radiation (0–6 Gy). H‐7 was toxic to cells at concentrations greater than 10 μM. Addition of H‐7 had no effect on the overall dose response of the HeLa cells to gamma radiation. These results suggest that the use of agents which inhibit protein kinase C activity does not necessarily result in decreased cell survival. © 1995 Wiley‐Liss, Inc.