Apoptotic effect in combination of Cyclosporin A and Taxol on oral squamous cell carcinoma cell line through the PI-3 kinase/Akt1 Pathway

Kim, Kyu Young; Lee, Jae Hoon

Abstract

Oral cancer take up 2-6% of all carcinomas and squamous cell carcinoma, which is the most common type in oral cancer, has a poor prognosis due to its high metastasis and recurrence rates. In treating oral cancer, chemotherapy to the primary, metastasized and recurrent lesion is a very important and useful treatment, even though its widespread usage is limited due to high general toxicity and local toxicity to other organs. Taxol, a microtubule stabilizing agent, is an anticancer drug that induces cell apoptosis by inhibiting depolymerization of microtubules in between the metaphase and anaphase of the cell mitosis. Recently, its effectiveness and mechanism on various tumor has been reported. However, not much research has been done on the application of Taxol to oral squamous cell carcinoma. Cyclosporin A, which is an immunosuppressant, is being used on cancers and when co-administered with Taxol, effectiveness of Taxol is enhanced by inhibition of Taxol induced multidrug resistance. In this study, Cyclosporin A with different concentration of Taxol was co-administered to HN22, the oral squamous cell carcinomacell line. To observe the cell apoptosis and the mechanisms that take part in this process, mortality evaluation of tumor cell using wortmannin, c-DNA microarray, RT-PCR analysis, cytometry analysis and western blotting were used, and based upon the observation on the effect and mechanism of the agent, the following results were obtained: 1. The HN22 cell line viability was lowest when 100micrometer of Wortmannin and 5microgram/ml of Taxol were co-administered, showing that Taxol participates in P13K-AKT1 pathway. 2. In c-DNA microarray, where 1microgram/ml of cyclosporine A and 3mg/ml of Taxol were co-administered, no up regulation of AKT1, PTEN and BAD c-DNA that participate in cell apoptosis was observed. 3. When 1microgram/ml of Cyclosporin A was applied alone to HN22 cell line,no difference was found in AKT1, PTEN and BAD mRNA expression. 4. Increased AKT1, mRNA expression was observed when 3microgram/ml of Taxol was applied alone to HN22 cell line. 5. When 1microgram/ml of Cyclosporin A and Taxol (3microgram/ml and 5microgram/ml) were co-administered to HN22 cell line, PTEN mRNA expression increased, whereas AKT1 and BAD mRNA decreased. 6. As a result of cytometry analysis, in the group of Cyclosporin A(1microgram/ml) and Taxol(3microgram/ml) co-administration, increased Annxin V was observed, which shows that apoptosis occurred by deformation of plasma membrane. However, no significant difference was observed with varying concentration. 7. In western blot analysis, no caspase 3 was observed in the group of Cyclosporin A(1microgram/ml) and Taxol(3microgram/ml) co-administration. From the results of this study, it can be concluded that synergistic effect can be observed in combination therapy of Taxol and Cyclosporin A on oral squamous cell carcinoma cell line, where decreased activity of the cell line was observed. This resulted in decreased AKT1 and BAD mRNA and increased PTEN mRNA expression and when wortmannin and Taxol were co-administered, the viability decreased which confirms that Taxol decreases the viability of tumor cell line. Hence, when Taxol and cyclosporine A are co-administered, it can be assumed that cell apoptosis occurs through AKt1 pathway.