[All-trans retinoic acid augments the bystander effect of herpes simplex virus thymidine kinase/ganciclovir system in the treatment of tongue carcinoma cell line].

OBJECTIVE: To investigate the augmentation effect and mechanism of all-trans retinoic acid (ATRA) on the bystander effect of herpes simplex virus thymidine kinase (HSV-TK)/ganciclovir (GCV) system in the treatment of tongue carcinoma cell line.

METHODS: Immunocytochemistry and flow cytometry (FCM) were used to analyze the expression of Cx43 protein in Tca8113 cells after treated with ATRA; The bystander effect of HSV-TK/GCV system on tongue carcinoma cells before and after treatment with ATRA was detected by MTT assays. The interaction of ATRA and bystander effect was analyzed by factorial experiment.

RESULTS: After treated by ATRA (10(-7) mol/L - 10(-5) mol/L), the expression of Cx43 protein was up-regulated in Tca8113 cells and the positive rate of Cx43 protein increased from 5.17% (before treatment) to 30.53% (10(-5) mol/L ATRA). There was significant difference between ATRA treated cells and untreated cells (P < 0.01). The bystander effect of HSV-TK/GCV system on Tca8113 cells was poor, but improved after combined with ATRA. There was cooperation effect between ATRA and bystander effect of HSV-TK/GCV (P < 0.05).

CONCLUSIONS: ATRA can augment the bystander effect of HSV-TK/GCV system in the treatment of tongue carcinoma cell line. The mechanism might be due to up-regulation of Cx43 gene and restore gap junction intercellular communication.