Glioblastoma (GBM) stem cells (GSC) are a subpopulation of tumor cells that display stem-like characteristics (stemness) and play unique roles in tumor propagation, therapeutic resistance, and tumor recurrence. Therapeutic targets in GSCs are a focus of increasing interest to improve GBM therapy. Here we report that the hyaluronan-mediated motility receptor (HMMR) is highly expressed in GBM tumors, where it supports the self-renewal and tumorigenic potential of GSCs. HMMR silencing impairs GSC self-renewal and inhibits the expression of GSC markers and regulators. Furthermore, HMMR silencing suppresses GSC-derived tumor growth and extends the survival of mice bearing GSC xenografts. Conversely, HMMR overexpression promotes GSC selfrenewal and intracranial tumor propagation. In human GBM tumor specimens, HMMR expression is correlated positively with the expression of stemness-associated markers and regulators. Our findings identify HMMR as a candidate therapeutic target to GSCs as a GBM treatment strategy. Cancer Res; 74(11); 3168-79. Ó2014 AACR.

The vertebrate retina develops from a sheet of neuroepithelial cells. Because adherens and tight junctions are critical for epithelial and neuronal differentiation in a variety of eukaryotic systems, we examined the role of Par-3, a PDZ scaffold protein that is critical in cellular membrane junction formation. We cloned the zebrafish Par-3 ortholog (pard3), which encodes two Pard3 proteins (150 and 180 kDa) that differ in their carboxyl-terminus. Immunohistochemistry revealed that Pard3 localized to the apical region of the retinal and brain neuroepithelium, partially overlapping the adherens junction-associated actin bundles. After retinal lamination, the Pard3 protein was restricted to the outer limiting membrane and the outer and inner plexiform layers in the retina. Reducing Pard3 expression with antisense morpholinos caused loss of the retinal pigmented epithelia, disruption of retinal lamination, and cell death in the ventral diencephalon, which resulted in cyclopia. Overexpressing Pard3 by injection of wild-type pard3 mRNA resulted in cyclopia and eyeless embryos. Thus, Pard3 plays a critical role in the origination and separation of zebrafish eye fields and retinal lamination.

The human PITX3 gene encodes a bicoid-like homeodomain transcription factor associated with a variety of congenital ocular conditions, including anterior segment dysgenesis, Peter's anomaly, and cataracts. We identified a zebrafish pitx3 gene encoding a protein (Pitx3) that possesses 63% amino acid identity with human PITX3. The zebrafish pitx3 gene encompasses approximately 16.5kb on chromosome 13 and consists of four exons, which is similar to the genomic organization of other pitx genes. Expression of the zebrafish pitx3 gene was studied by in situ mRNA hybridization and RT-PCR. The pitx3 transcripts were detected throughout development with the greatest level of expression occurring in the developing lens and brain at 24hpf. In adults, the highest expression was detected in the eye. Morpholinos were used to knockdown expression of the Pitx3 protein and a control morpholino that contains five mismatched bases was used to confirm the specificity of the phenotypes. The morphants had small eyes, misshapen heads and reduced jaws and fins relative to controls. The morphants exhibited abnormalities in lens development and their retinas contained pyknotic nuclei accompanied by a reduction in the number of cells in different neuronal classes. This suggests the lens is required for retinal development or Pitx3 has an unexpected role in retinal cell differentiation or survival. These results demonstrate zebrafish pitx3 represents a true ortholog of the human PITX3 gene and the general function of the Pitx3 protein in lens development is conserved between mammals and the teleost fish.