Characterization of the metastatic phenotype of a panel of established osteosarcoma cells

Abstract

Osteosarcoma (OS) is the most common bone tumor in pediatric patients. Metastasis is a major cause of mortality and morbidity. The rarity of this disease coupled with the challenges of drug development for metastatic cancers have slowed the delivery of improvements in long-term outcomes for these patients. In this study, we collected 18 OS cell lines, confirmed their expression of bone markers and complex karyotypes, and characterized their in vivo tumorgenicity and metastatic potential. Since prior reports included conflicting descriptions of the metastatic and in vivo phenotypes of these models, there was a need for a comparative assessment of metastatic phenotypes using identical procedures in the hands of a single investigative group. We expect that this single characterization will accelerate the study of this metastatic cancer. Using these models we evaluated the expression of six previously reported metastasis-related OS genes. Ezrin was the only gene consistently differentially expressed in all the pairs of high/low metatstatic OS cells. We then used a subtractive gene expression approach of the high and low human metastatic cells to identify novel genes that may be involved in OS metastasis. PHLDA1 (pleckstrin homology-like domain, family A) was identified as one of the genes more highly expressed in the high metastatic compared to low metastatic cells. Knocking down PHLDA1 with siRNA or shRNA resulted in down regulation of the activities of MAPKs (ERK1/2), c-Jun N-terminal kinases (JNK), and p38 mitogen-activated protein kinases (MAPKs). Reducing the expression of PHLDA1 also delayed OS metastasis progression in mouse xenograft models.

Pleckstrin homology-like domain, family A, member 1 (PHLDA1) and cancer

“…However, PHLDA1 was reported to be upregulated in colon cancer and in human intestinal adenoma and carcinoma, and PHLDA1 knockdown in colon cancer cells inhibits anchorage-independent cell growth and reduces cell migration (17,38). Furthermore, high expression of PHLDA1 is associated with high metastatic potential in osteosarcoma cells and reduced PHLDA1 expression delays overall survival metastasis progression in mouse xenograft models (39). These findings suggest that PHLDA1 has tissue-specific functions and may have an oncogenic role in other cancer types.…”

Upregulation of Glucose-Regulated Protein 78 in Metastatic Cancer Cells Is Necessary for Lung Metastasis Progression

“…MNNG, 143B, and 4T1 cells are characterized to have a highly metastatic phenotype in vivo [20], [21]. The MG63.3 cell line is a highly metastatic clonal variant of the human OS cell line established from MG63.2 cells, which were in turn established from the MG63 cell line [21]. The MG63, HOS, and 67NR cell lines were previously characterized to have a poorly metastatic phenotype in vivo [20].…”

Ezrin Inhibition Up-regulates Stress Response Gene Expression

“…K7M2 cells express higher levels of ezrin protein, which leads to a greater potential to metastasize to the lungs than K12 cells (25). MG63.3 cells were derived from MG63.2 using in vivo passage by a process of experimental metastasis (25,26).…”