Galectin-1, a gene preferentially expressed at the tumor margin, promotes glioblastoma cell invasion
1 The Texas Brain and Spine Institute, 8441 St. Hwy 47, Suite 4300, Bryan, TX, 77807, USA
2 Department of Neuroscience and Experimental Therapeutics, Texas A&M HSC College of Medicine, 2006 MREB, 8447 St. Hwy 47, Bryan, TX, 77807, USA
3 Department of Neurology, Mayo Clinic, Rochester, MN, USA
4 Division of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, MN, USA
5 Department of Neurological Surgery, UCSF, San Francisco, CA, USA
6 Service de Neurochirurgie, Hôpital Erasme, Université Libre de Bruxelles, Brussels, Belgium
7 Laboratoire de Toxicologie, Faculté de Pharmacie, Université Libre de Bruxelles, Brussels, Belgium
Molecular Cancer 2012, 11:32 doi:10.1186/1476-4598-11-32Published: 14 May 2012
High-grade gliomas, including glioblastomas (GBMs), are recalcitrant to local therapy in part because of their ability to invade the normal brain parenchyma surrounding these tumors. Animal models capable of recapitulating glioblastoma invasion may help identify mediators of this aggressive phenotype.
Patient-derived glioblastoma lines have been propagated in our laboratories and orthotopically xenografted into the brains of immunocompromized mice. Invasive cells at the tumor periphery were isolated using laser capture microdissection. The mRNA expression profile of these cells was compared to expression at the tumor core, using normal mouse brain to control for host contamination. Galectin-1, a target identified by screening the resulting data, was stably over-expressed in the U87MG cell line. Sub-clones were assayed for attachment, proliferation, migration, invasion, and in vivo tumor phenotype.
Expression microarray data identified galectin-1 as the most potent marker (p-value 4.0 x 10-8) to identify GBM cells between tumor-brain interface as compared to the tumor core. Over-expression of galectin-1 enhanced migration and invasion in vitro. In vivo, tumors expressing high galectin-1 levels showed enhanced invasion and decreased host survival.
In conclusion, cells at the margin of glioblastoma, in comparison to tumor core cells, have enhanced expression of mediators of invasion. Galectin-1 is likely one such mediator. Previous studies, along with the current one, have proven galectin-1 to be important in the migration and invasion of glioblastoma cells, in GBM neoangiogenesis, and also, potentially, in GBM immune privilege. Targeting this molecule may offer clinical improvement to the current standard of glioblastoma therapy, i.e. radiation, temozolomide, anti-angiogenic therapy, and vaccinotherapy.