Carbon ion irradiation abrogates Lin28B-induced X-ray resistance in melanoma cells

The lin28/let-7 axis plays an important role in tumor initiation and developmental processes. lin28b is upregulated in a variety of cancers,and its overexpression enhances cancer cell proliferation and radioresistance through the suppression of let-7 micro rna expression. in this study,we investigated the role of the lin28/let7 axis as a target for radiosensitization of melanoma cancer cells. the overexpression of lin28b reduced mature let-7 microrna expression in melanoma cell lines,and enhanced the sphere-forming ability of melanoma cell lines,which is a characteristic of cancer stem cell (csc) populations. interestingly,lin28b-overexpressed melanoma cells were more resistant to x-ray irradiation than control cells,and lin28b-induced radioresistance was abolished after carbon ion irradiation. consistent with these results,lin28b overexpression reduced the numbers of γh2a.x foci after x-ray irradiation,whereas carbon ion irradiation had no such effect. our results suggest that a carbon ion beam is more effective than an x-ray beam in terms of killing cancer cells,possibly due to elimination of csc populations. © the author 2017.