Influence of gap junctional intercellular communication on heavy ion irradiation induced cell responses

Objective: To investigate the influence of GJIC on heavy-ion irradiation induced cellular damage and associated mechanism. Methods: Primary human fibroblast AG1522 and human neoplastic HSG cells under confluence were irradiated with high-energy carbon beam. The influence of gap junctional intercellular communication (GJIC) on radiation responses of micronucleus (MN) formation and cycle arrest was measured. Results: Cell lethal damage and cell cycle arrest were induced by high energy carbon beam, and AG1522 cells had radiosensitivity higher than HSG cells. For irradiated AG1522, cellular damage was positively adjusted by GJIC. However, with respect to irradiated HSG cells, cell damage was diminished by enhanced GJIC. Moreover, MN in AG1522 was reduced by DMSO and MN in HSG cells was increased by PTIO. Conclusions: GJIC increases radiation damage on primary fibroblasts but has radiation protective effect on tumor cells. ROS and NO may contribute to these GJIC mediated radiation responses on AG1522 and HSG cells, respectively. (authors)