The Cancer Therapeutic Potential of RGD Derivatized Dihydrolipoamide Dehydrogenase Complexed with Titanium Dioxide Nanoparticles

The Reactive Oxygen Species (ROS)-dependent phototoxic effect of UV-excited titanium dioxide (TiO₂), has been demonstrated in several cancer models of PhotoDynamic Therapy (PDT). However, serious damage to the surrounding healthy tissue limits the applicability of this approach. Targeted delivery of TiO₂ towards cancer cell would make PDT more selective. Cancer cells often overexpress integrin receptors (e.g. avb3) on their surface, which interact with proteins of the extra cellular matrix through RGD (Arg-Gly-Asp) recognition sites.

Studies in our lab has shown that Dihydrolipoamide dehydrogenase (DLDH) has strong TiO₂-binding capabilities. Bio-engineering of DLDH with RGD moieties (DLDH^RGD), generated a nanobiocomplex (protein with TiO₂ nanoparticles) capabilities with high affinity to the integrin expressing cancer cells. We have demonstrated that the nanobiocomplex possesses a UV-excitable cytotoxicity in cutaneous melanoma cells (B16F10) while normal kidney cells (HEK293) remain unharmed.

The activity of mitochondrial dehydrogenases (such as DLDH), is often associated with elevated levels of ROS production, leading to pro-apoptotic activity. DNA binding of these enzymes was suggested to contribute to the cytotoxic effect. Our studies showed that DLDH possesses both activity-dependent ROS production and DNA binding properties. We examined the cytotoxic effects of DLDH^RGD and its potential use as an anti-cancer drug with cutaneous melanoma (B16F10) and glioblastoma (005) cancers cell lines. Normal kidney (HEK293) and cortex (NF5310) were unharmed. DLDH^RGD incorporation into the cancer cells and apoptosis induction were analyzed by confocal and FACS assays.

In-vivo assay showed positive safety profile using IV, SC and IP, and high efficacy (murine B16F10 model in C57bL). Currently the efficacy of DLDH^RGD on Glioblastoma (murine 005 model in BALB/C) including BBB penetration are under investigation.