The knocking down of the oncoprotein Golgi phosphoprotein 3 in T98G cells of glioblastoma multiforme disrupts cell migration by affecting focal adhesion dynamics in a focal adhesion kinase-dependent manner

Abstract

Golgi phosphoprotein 3 (GOLPH3) is a conserved protein of the Golgi apparatus that in humans has been implicated in tumorigenesis. However, the precise function of GOLPH3 in malignant transformation is still unknown. Nevertheless, clinicopathological data shows that in more than a dozen kinds of cancer, including gliomas, GOLPH3 could be found overexpressed, which correlates with poor prognosis. Experimental data shows that overexpression of GOLPH3 leads to transformation of primary cells and to tumor growth enhancement. Conversely, the knocking down of GOLPH3 in GOLPH3-overexpressing tumor cells reduces tumorigenic features, such as cell proliferation and cell migration and invasion. The cumulative evidence indicate that GOLPH3 is an oncoprotein that promotes tumorigenicity by a mechanism that impact at different levels in different types of cells, including the sorting of Golgi glycosyltransferases, signaling pathways, and the actin cytoskeleton. How GOLPH3 connects mechanistically these processes has not been determined yet. Further studies are important to have a more complete understanding of the role of GOLPH3 as oncoprotein. Given the genetic diversity in cancer, a still outstanding aspect is how in this inherent heterogeneity GOLPH3 could possibly exert its oncogenic function. We have aimed to evaluate the contribution of GOLPH3 overexpression in the malignant phenotype of different types of tumor cells. Here, we analyzed the effect on cell migration that resulted from stable, RNAi-mediated knocking down of GOLPH3 in T98G cells of glioblastoma multiforme, a human glioma cell line with unique features. We found that the reduction of GOLPH3 levels produced dramatic changes in cell morphology, involving rearrangements of the actin cytoskeleton and reduction in the number and dynamics of focal adhesions. These effects correlated with decreased cell migration and invasion due to affected persistence and directionality of cell motility. Moreover, the knocking down of GOLPH3 also caused a reduction in autoactivation of focal adhesion kinase (FAK), a cytoplasmic tyrosine kinase that regulates focal adhesions. Our data support a model in which GOLPH3 in T98G cells promotes cell migration by stimulating the activity of FAK.

The Great Escape: how phosphatidylinositol 4-kinases and PI4P promote vesicle exit from the Golgi (and drive cancer)

“…Very strikingly, altered expression of GOLPH3 and Myosin-18A are associated with a range of malignant phenotypes including tumour secretion (41), increased trafficking to the leading edge of migratory cells and consequently augmented cell motility, loss of cell-cell adhesion and invasion (39,45,49,50,(218)(219)(220)(221)(222)(223)(224)(225). However, while this model is strongly supported by a wealth of experimental data, there is at least one report indicating that Myosin-18A is neither localised to the Golgi nor required for its characteristic ribbon like structure (226).…”

Oncogenic Roles of GOLPH3 in the Physiopathology of Cancer

“…Similar results were obtained by inhibiting YB1 using specific siRNA or by using INK128, an inhibitor of both mTOR complexes (mTORC1/2) [14]; in both cases, artificially increasing the GOLPH3 levels alone had no effects on cell motility, showing that the mTOR-YB1 pathway was pivotal for GBM invasiveness. Recently, Arriagada and co-workers [63] reported that knocking down GOLPH3 through RNAi can deeply alter the cell morphology of a T98G cell line of GBM. This occurs because of the actin cytoskeleton rearrangement and the reduction and dynamics of focal adhesions, which in turn affect both their motility and invasive behavior.…”

GOLPH3 Regulates EGFR in T98G Glioblastoma Cells by Modulating Its Glycosylation and Ubiquitylation

“…Increasing evidence shows that GOLPH3 is overexpressed in different types of human tumors, including glioblastoma multiforme (GBM) [ 32 , 34 , 35 , 36 ]. Likewise, human glioma cell lines such as A172, U87, U118, U251, and T98G cells overexpress GOLPH3 [ 32 , 35 , 37 ]. Moreover, overexpression of GOLPH3 in these cell lines results in increased cell migration and cell invasion [ 32 , 35 , 37 ], which are hallmarks of oncogenic transformation [ 38 ].…”