ABSTRACT: We have used human umbilical vein endothelial cell line (HUVEC) as a model to investigate the effect of ultrasound (US) activated micro-bubbles on sensitizing the tumour response to radiation and to check the implication of this approach on gene expression. The use of micro-bubbles in cancer therapy is a novel approach that is being recently investigated, and patterns of gene expressions were not yet characterized. Gene analysis has identified about 19,264 genes; where, 239 – 517 genes have shown more than two folds up-regulation in response to the different treatments. This included a number of genes that are known to be involved in apoptosis and ceramide-induced apoptosis pathways, such as Sphingomyelin phosphodiesterase 2, neutral sphingomyelinase (SMPD2), sphingomyelin phosphodiesterase 1, acid lysosomal (ASM; SMPD1), UDP-galactose ceramide galactosyltransferase (UGT8), cytochrome c oxidase (COX6B1), Caspase-9 and mitogen-activated protein kinase kinase 1 (MAP2K1). To verify these results, we have performed Real time RT-PCR, which indicated an up-regulation that ranged from 2 to 200 folds, specifically in the combined treatment of US, 3.3% micro-bubbles and 8 Gy. The observed higher levels of expression of UGT8, SMPD2 and Caspase 9-alpha when compared to the control or to radiation only indicated the involvement of ceramide, which possibly induces apoptosis . These results support the hypothesis that micro-bubbles play a role in increasing sensitization to radiation, and can prove to be an effective cancer therapeutic approach. Gene analysis has identified about 19,264 genes; where, 239 – 517 genes have shown more than two folds up-regulation in response to the different treatments. This included a number of genes that are known to be involved in apoptosis and ceramide-induced apoptosis pathways, such as Sphingomyelin phosphodiesterase 2, neutral sphingomyelinase (SMPD2), sphingomyelin phosphodiesterase 1, acid lysosomal (ASM; SMPD1), UDP-galactose ceramide galactosyltransferase (UGT8), cytochrome c oxidase (COX6B1), Caspase-9 and mitogen-activated protein kinase kinase 1 (MAP2K1). To verify these results, we have performed Real time RT-PCR, which indicated an up-regulation that ranged from 2 to 200 folds, specifically in the combined treatment of US, 3.3% micro-bubbles and 8 Gy. The observed higher levels of expression of UGT8, SMPD2 and Caspase 9-alpha when compared to the control or to radiation only indicated the involvement of ceramide, which possibly induces apoptosis . These results support the hypothesis that micro-bubbles play a role in increasing sensitization to radiation, and can prove to be an effective cancer therapeutic approach.
