Antisense-mediated downregulation of anti-apoptotic proteins induces apoptosis and sensitizes head and neck squamous cell carcinoma cells to chemotherapy

We have earlier reported that the inhibition of apoptosis in head and neck squamous cell carcinomas (HNSCC) is because of upregulated expression of Bcl-2, Bcl-XL and Survivin. Hence, we addressed the question whether antisense approach towards these inhibitors of apoptosis could restore the apoptosis in HNSCC. Further, we wanted to see whether chemotherapeutic efficacy of Cisplatin and Etoposide could be enhanced by using these drugs in combination with antisense oligonucleotides in human laryngeal carcinoma HeP2 and tongue carcinoma Cal27 cells. The effect of these antisense oligonu- cleotides was examined on the mRNA expression by RT-PCR and on protein expression by Western blotting. Apoptosis was measured by flowcytometry, TUNEL assay and caspase-3 activity assay. Treatment of HeP2 and Cal27 cells with 400nM antisense oligonucleotides against Bcl-2, Bcl-X and Survivin for 48 hrs decreased their expression both at the mRNA L as well as at the protein level, resulting in the induction of apoptosis. Treatment of HeP2 and Cal27 cells with these antisense oligonucleotides augmented Cisplatin and Etoposide induced apoptosis. Our findings emphasize the importance of Bcl-2, Bcl-X and Survivinas survival factors in HNSCC cells. Antisense treatment against these survival factors incombination with lower doses of chemotherapy offers potential as a less toxic chemoadjuvant therapy.