Caveolin-1 enhances resveratrol-mediated cytotoxicity and transport in a hepatocellular carcinoma model.

BACKGROUND

Resveratrol (RES), an estrogen analog, is considered as a potential cancer chemo-preventive agent. However, it remains unclear how RES is transported into cells. In this study, we observed that Caveolin-1(CAV1) expression can increase the cytotoxic and pro-apoptotic activity of RES in a dose- and time-dependent manner both in vitro and in vivo in a Hepatocellular Carcinoma animal model.

METHODS

High performance liquid chromatography (HPLC) demonstrated that RES intra-cellular concentration is increased about 2-fold in cells stably expressing CAV1 or CAVM1 (a scaffolding domain (81-101AA)-defective CAV1 mutant) compared to the untransduced human Hepatoblastoma cell line (HepG2) or after transduction with the green fluorescent protein (GFP) control vector. The increased intra-cellular transport of RES was abolished in cells stably expressing CAVM2 (a cholesterol shuttle domain (143-156AA)-defective CAV1 mutant) or CAVRNAi. In order to further characterize CAV1-dependent RES transport, we synthesized RES-dansyl chloride derivatives as fluorescent probes to visualize the transport process, which demonstrated a distribution consistent with that of CAV1 in HepG2 cells.

RESULTS

In addition, RES endocytosis was not mediated by estrogen receptor (ER) alpha and beta, as suggested by lack of competitive inhibition by estrogen or Tamoxifen. Pathway analysis showed that RES can up-regulate the expression of endogenous CAV1; this activates further the MAPK pathway and caspase-3 expression.

DISCUSSION: This study provides novel insights about the role played by CAV1 in modulating cellular sensitivity to RES through enhancement of its internalization and trafficking.