This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Ozvaran, M. K. Articles by Smythe, W. R. Search for Related Content PubMed PubMed Citation Articles by Ozvaran, M. K. Articles by Smythe, W. R.

Departments of ¹ Thoracic and Cardiovascular Surgery and ² Cancer Medicine, The University of Texas M.D. Anderson Cancer Center, Houston, Texas; and ³ Isis Pharmaceuticals, Carlsbad, California

Requests for Reprints: W. Roy Smythe, Section of Thoracic Molecular Oncology, Department of Thoracic and Cardiovascular Surgery, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe, Box 445, Houston, TX 77030. Phone: (713) 792-6933; Fax: (713) 792-8469. E-mail: rsmythe{at}mdanderson.org

Objective: Malignant pleural mesothelioma (MPM) is resistant to both conventional chemotherapy and apoptosis. The bcl-2 family proteins are major determinants of apoptotic homeostasis. MPM lines and tumors routinely overexpress the anti-apoptotic protein BCL-XL. We have previously shown that antisense inhibition of BCL-XL in MPM cells leads to apoptosis. We sought to determine whether antisense oligonucleotides directed at the bcl-xl gene product would augment response to a conventional chemotherapeutic agent in human mesothelioma cell lines.

Methods: The human MPM cell lines REN and I-45 were exposed to two bcl-xl antisense oligonucleotides (15999, 16009) and one sense oligonucleotide (113529) construct at varying doses, followed by IC₅₀ cisplatin. Cellular viability was assessed by a calorimetric assay, and apoptosis was evaluated by Hoechst staining, Annexin V staining, and sub-G₁ fluorescence-activated cell sorter analysis. Western blot analysis of BCL-2 family proteins was performed following single agent and combined treatment. Isobologram mathematical analysis was used to determine whether or not combination therapies were additive or synergistic.

Results: Cell viability was most affected with the 15999 antisense oligonucleotides plus IC₅₀ cisplatin combination (70% of I-45 and 90% of REN cells killed), and apoptosis was markedly increased with this combination by all measures. Western blot demonstrated 15999 antisense oligonucleotides construct down-regulation of BCL-XL, but no further effect on expression of BCL-2 proteins with cisplatin. Isobologram analysis demonstrated 15999 + cisplatin synergistic effect.

Conclusions: Exposure of human MPM cells to bcl-xl antisense oligonucleotides sensitizes human mesothelioma cells to the conventional chemotherapeutic agent cisplatin. Similar approaches using a combination of molecular and conventional treatment may have clinical utility for this tumor.

Key Words: Mesothelioma • antisense • bcl-xl • cisplatin

Grant support: University of Texas M.D. Anderson Cancer Center Physician Scientist Award and Grant (W.R. Smythe); grant DAMD 17-02-1-0706 from the Department of Defense; and W.M. Keck Foundation and Center for Cancer Gene Therapy.

The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

Note: This paper was presented at the 82nd Annual Meeting of the American Association for Thoracic Surgery.

Received 5/22/03; revised 2/ 3/04; accepted 3/17/04.