Therapeutic Efficacy Evaluation of Curcumin on Human Oral Squamous Cell Carcinoma Xenograft Using Multimodalities of Molecular Imaging

Oral squamous cell carcinoma (OSCC) is the most common malignancy of the oral cavity; however the treatment approaches are still unsatisfactory. We used a luciferase-transfected animal model to evaluate the therapeutic effects of curcumin. Human oral squamous cell carcinoma SAS cell line was stably transfected with luc gene, named SAS/luc cells. For the in vivo study, they were inoculated subcutaneously to 6-week-old male NOD/SCID mice which were separated into four groups for intraperitoneal injection (i.p.) of curcumin: control, daily with 35 mg/kg, 70 mg/kg every 2 days, and 100 mg/kg every 3 days. We applied SAS/luc bearing animal model and bioluminescent imaging (BLI) to study the inhibition effect of curcumin on tumor growth. The cytotoxic effect of curcumin on SAS/luc cells was mainly at G2/M phase and a significant dose dependent increase of the apoptotic SAS/luc cells as represented by sub-G1 phase was shown. Therapeutic efficacy evaluated by both caliper assay and BLI showed a significant difference between curcumin-treated mice and the controls (p < 0.01). The significant inhibition effects of curcumin on the proliferation and the growth of human OSCC are observed both in vitro and in vivo. No significant body weight change (i.e. within 20%) was observed in all SAS/luc-bearing mice with or without curcumin treatment. This SAS/luc human OSCC bearing animal model combined with multimodalities of molecular imaging permits a sensitive and non-invasive approach to evaluate the therapeutic efficacy in vivo.