Development of Novel Therapeutic Agents and Modalities Against Gliomas

Charles A. Conrad, M.D.

My research centers on the development of novel therapeutic agents and modalities against gliomas. In recent experiments, we used proteomic analysis to identify key proteins or protein expression signatures under the influence of transfection with wild-type p53 and additional treatment of cytotoxic chemotherapy with SN- 38, initially in the high-grade glioma cell line U87 MG, which harbors wild-type p53. Of all the proteins identified, one protein, galectin-1, was found to be dramatically modulated when the cells were treated with wt p53 and SN-38.

Galectin-1 is an ubiquitous protein with many receptors and is involved in biological functions such as cell adhesion, cell proliferation, tumor metastasis, apoptosis and immunoregulatory effects. Expression of galectin-1 has been shown to be associated with malignancy and poor prognosis. In our study, treatment of the U87 cell line with p53 demonstrated a reduction of the expression of galectin-1 and the addition of both p53 and SN- 38 decreased the amount of galectin-1 even more dramatically. Other high-grade glioma cell lines that we investigated displayed high levels of galectin-1, which indicates that the protein is up-regulated during the course of glioma development. We found that both subcutaneous and intracranical xenograft tumors in mice express high amounts of galectin-1, and the expression of the protein appears to be more prominent at the leading edge of the expanding tumor. Further, we demonstrated a clear increase in sensitivity to the cyototoxic chemotherapy SN- 38 after siRNA treatment, which could have direct implications to clinical therapies that target galectin-1; however, simultaneous treatment of siRNA and recombinant galectin-1 protein partially abrogates the increase in sensitivity. Microarray analysis of a panel of samples from patients with high-grade gliomas demonstrated that patients who had poor survival (defined as surviving less than one year) as compared to patients who had good survival (defined as surviving less than two years), showed a positive correlation between increased galectin- 1 expression and poor patient survival. Taken together, the data may indicate that galectin-1 could be used as a therapeutic target to increase cell sensitivity to cytotoxic agents.

Selected Publications

Aoki H, Kondo Y, Aldape K, Yamamoto A, Iwado E, Yokoyama T, Hollingsworth EF, Kobayashi R, Hess K, Shinojima N, Shingu T, Tamada Y, Zhang L, Conrad C, Bögler O, Mills G, Sawaya R, Kondo S. Monitoring Autophagy in Glioblastoma with Antibody against Isoform B of Human Microtubule-Associated Protein 1 Light Chain 3. Autophagy. 2008 Feb 4;4(4) [Epub ahead of print]

He H, Conrad CA, Nilsson CL, Ji Y, Schaub TM, Marshall AG, Emmett MR. Method for lipidomic analysis: p53 expression modulation of sulfatide, ganglioside and phospholipid composition of U87 MG glioblastoma cells. Anal Chem. 2007 Nov 15;79(22):8423-30. Epub 2007 Oct 12.

Iwamaru A, Szymanski S, Iwado E, Aoki H, Yokoyama T, Fokt I, Hess K, Conrad C, Madden T, Sawaya R, Kondo S, Priebe W, Kondo Y. A novel inhibitor of the STAT3 pathway induces apoptosis in malignant glioma cells both in vitro and in vivo. Oncogene 26: 2435-2444, 2007.

Gonzalez J, Kumar AJ, Conrad CA, Levin VA. Effect of bevacizumab on radiation necrosis of the brain. Int J Radiat Oncol Biol Phys 67: 323-326, 2007.

Puchades M, Nilsson CL, Emmett MR, Aldape KD, Ji Y, Lang FF, Liu TJ, Conrad CA. Proteomic investigation of glioblastoma cell lines treated with wild-type p53 and cytotoxic chemotherapy demonstrates an association between galectin-1 and p53 expression. J Proteome Res 6: 869-875, 2007.

Guo W, Zhu H, Zhang L, Davis J, Teraishi F, Roth JA, Stephens C, Fueyo J, Jiang H, Conrad C, Fang B. Combination effect of oncolytic adenovirotherapy and TRAIL gene therapy in syngeneic murine breast cancer models. Cancer Gene Ther 13: 82-90, 2006.

Goudar RK, Shi Q, Hjelmeland MD, Keir ST, McLendon RE, Wikstrand CJ, Reese ED, Conrad CA, Traxler P, Lane HA, Reardon DA, Cavenee WK, Wang XF, Bigner DD, Friedman HS, Rich JN. Combination therapy of inhibitors of epidermal growth factor receptor/vascular endothelial growth factor receptor 2 (AEE788) and the mammalian target of rapamycin (RAD001) offers improved glioblastoma tumor growth inhibition. Mol Cancer Ther 4: 101-112, 2005.

Heimberger AB, Wang E, McGary EC, Hess KR, Henry VK, Shono T, Cohen Z, Gumin J, Sawaya R, Conrad CA, Lang FF. Mechanisms of action of rapamycin in gliomas. Neuro-oncol 7: 1-11, 2005.

Conrad C, Miller CR, Ji Y, Gomez-Manzano C, Bharara S, McMurray JS, Lang FF, Wong F, Sawaya R, Yung WK, Fueyo J. Delta24-hyCD adenovirus suppresses glioma growth in vivo by combining oncolysis and chemosensitization. Cancer Gene Ther 12: 284-294, 2005.

Jiang H, Alemany R, Gomez-Manzano C, Medrano DR, Lemoine MG, Olson MV, Alonso MM, Lee OH, Conrad CC, Yung WK, Fueyo J. Downmodulation of E1A protein expression as a novel strategy to design cancer-selective adenoviruses. Neoplasia 7: 723-729, 2005.

Gomez-Manzano C, Balague C, Alemany R, Lemoine MG, Mitlianga P, Jiang H, Khan A, Alonso M, Lang FF, Conrad CA, Liu TJ, Bekele BN, Yung WK, Fueyo J. A novel E1A-E1B mutant adenovirus induces glioma regression in vivo. Oncogene 23: 1821-1828, 2004.