Anticancer effect of gold (III) porphyrin in nasopharyngeal carcinoma

Abstract

Chinese population, especially in southern China, has the highest incidence of nasopharyngeal carcinoma (NPC) in the world. Current treatment modalities include radiotherapy and chemotherapy, in which cisplatin is commonly used. Cisplatin-resistance, however, occurs in about 30-40% of treated individuals. Newer drugs with more potent effectiveness are therefore in need. Gold(III) porphyrin has been shown to inhibit survival of various cancer cells in vitro (Che CM et al, 2003). Here we report that from MTT assay, gold(III) porphyrin effectively inhibited growth of NPC cell lines, cisplatin-sensitive SUNE1 cells and cisplatin-resistant CNE2 cells, with an IC50 0.12±0.02 μM and 0.14±0.01 μM respectively, both of which are 100 fold more potent compared with that of cisplatin (16.5±1.04μM for SUNE1 and 89.3±5.21 μM for CNE2). Annex-V/PI staining indicated that gold(III) porphyrin-indiced growth inhibition of NPC cell lines in vitro is due to induction of apoptosis. In tumour-implanted mice, we also showed that administration of 3 mg/kg/wk gold(III) porphyrin compound induces significant inhibition of tumour growth, compared to treatment with vehicle control or cisplatin. Of note, such a treatment was not associated with body weight loss or noticeable side effects. Immunohistology study confirmed that gold(III) porphyrin induced apoptosis of tumour cells through intrinsic pathway with an increase of caspase 9 expression. Gold(III) porphyrin, therefore, may become a potential chemotherapeutic agent for NPC.