Blockage of transdifferentiation from fibroblast to myofibroblast in experimental ovarian cancer models.
BACKGROUND
Tumour stromal myofibroblasts can promote tumour invasion. As these cells are genetically more stable than cancer cells, there has been enormous interest in developing targeted molecular therapies against them. Chloride intracellular channel 4 (CLIC4) and reactive oxygen species (ROS) have been linked with promoting stromal cell transdifferentiation in various cancers, but little is known of their roles in ovarian cancer. In this study, we examined the functional roles that both CLIC4 and ROS play in the process of ovarian cancer cell-stimulated or TGF-beta1 induced fibroblast-to-myofibroblast transdifferentiation. We also examine whether it is possible to reverse such a process, with the aim of developing novel therapies against ovarian cancer by targeting activated transdifferentiated myofibroblasts.


RESULTS
We demonstrate that TGF-beta1 induced or CM(SKOV3) activate transdifferentiated myofibroblasts (fibroblasts). These fibroblasts mimic "reactive" stromal myofibroblasts and demonstrate significant up-regulation of CLIC4 expression and increased level of ROS production. Blocking the production of ROS with an antioxidant consequently reduces the expression of CLIC4, and is accompanied by disappearance of alpha-smooth-muscle actin (alpha-SMA), a myofibroblast marker, suggesting ROS acts as a signalling molecule that promotes and enhances CLIC4 activities in the myofibroblast transdifferentiaton process. Down-regulation of CLIC4 with a generic agent or specific siRNA both significantly reduces the expression of factors related to the phenotypes and functions of myofibroblasts, such as alpha-SMA, hepatocyte growth factor (HGF) and vascular endothelial growth factor (VEGF), thus reversing the myofibroblast phenotype back to fibroblasts. These results convincingly show that ROS and CLIC4 are responsible for TGF-beta1 induced fibroblast-to-myofibroblast transdifferentiaton and down-regulation of both is sufficient to block transdifferentiated myofibroblasts.


CONCLUSIONS
Molecular targeting of ROS and CLIC4 has the potential to develop novel therapies for ovarian cancer.
Division of Molecular and Gene Therapies, Griffith Institute for Health and Medical Research, School of Medical Science, Griffith University, Gold Coast campus, Southport, Qld 4222, Australia.
Qin
Q
Yao
Xun
X
Qu
Qifeng
Q
Yang
David A
DA
Good
Shuzhen
S
Dai
Beihua
B
Kong
Ming Q
MQ
Wei
D054338:Cell Transdifferentiation / Q000187:drug effects; D018118:Chloride Channels / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D017077:Culture Media, Conditioned / Q000494:pharmacology; D005260:Female; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D010051:Ovarian Neoplasms / Q000378:metabolism / Q000473:pathology*; D010641:Phenotype; D017382:Reactive Oxygen Species / Q000378:metabolism; D017154:Stromal Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology; D015854:Up-Regulation
C464459:CLIC4 protein, human; D018118:Chloride Channels; D017077:Culture Media, Conditioned; D017382:Reactive Oxygen Species; D053773:Transforming Growth Factor beta1