The microenvironment induces collective migration in SDHB-silenced mouse pheochromocytoma spheroids

Abstract

Pheochromocytomas (Pheos) and paragangliomas (PGLs) are neuroendocrine tumors. Approximately 30-40% of Pheos/PGLs are due to germline mutations in one of the susceptibility genes, including those encoding the succinate dehydrogenase subunits A-D (). Up to 2/3 of patients affected by mutated Pheo/PGL develop metastatic disease with no successful cure at present. Here, for the first time, we evaluated the effects of silencing in a three dimension (3D) culture using spheroids of a mouse Pheo cell line silenced or not (wild type/wt/control) for the SDHB subunit. We investigated the role of the microenvironment on spheroid growth and migration/invasion by co-culturing -silenced or wt spheroids with primary cancer-activated fibroblasts (CAFs). When spheroids were co-cultured with fibroblasts,-silenced cells showed a significant increase in matrigel invasion as demonstrated by the computation of the migratory areas ( < 0.001). Moreover, cells detaching from the -silenced spheroids moved collectively, unlike the cells of wt spheroids that moved individually. Additionally,silenced spheroids developed long filamentous formations along which clusters of cells migrated far away from the spheroid, whereas these structures were not present in wt spheroids. We found that lactate, largely secreted by CAFs, plays a specific role in promoting migration only of -silenced cells. In this study, we demonstrated that silencing increases tumor cell migration/invasion and that microenvironment, as represented by CAFs, plays a pivotal role in enhancing collective migration/invasion in Pheo-silenced tumor cells, suggesting their role in increasing the tumor metastasizing potential.

Succinate dehydrogenase deficiency in a chromaffin cell model retains metabolic fitness through the maintenance of mitochondrial NADH oxidoreductase function

“…One-way ANOVA was used to assess statistical significance; **** P ≤ .0001 PPGL, which are characterized by the presence of significant number of defective mitochondria. 24,25 Indeed, a similar mitochondrial morphology and increase in mass was observed in other SDHB-mutated tumor types as well as in Sdhb +/− mice. 26,27 However, this increase may come at a cost to the cell; the mitochondria themselves are less efficient, and even small increases in electron flow were found to result in a reduction in viability (Figure 1 G).…”

Advances in paraganglioma–pheochromocytoma cell lines and xenografts

“…MTT has also been used recently in conjunction with shRNA-mediated knockdown (KD) of Sdhb (D'Antongiovanni et al 2017. This strategy effectively combines aspects of cluster 1 and cluster 2 tumors, together with an unknown genetic contribution from the original irradiation of the MPC cell line and other poorly understood characteristics of that cell line, particularly the continued expression of neurofibromin.…”

Germline Mutation in KIF1Bβ Gene Associated with Loss of Heterozygosity: Usefulness of Next-Generation Sequencing in the Genetic Screening of Patients with Pheochromocytoma

“…Ultrathin sections were stained with gadolinium acetate and alkaline bismuth subnitrate and examined under a JEM 1010 electron microscope (Jeol, Tokyo, Japan) at 80 kV. Photomicrographs were taken with a MegaView III (Soft Imaging System, Muenster, Germany) digital camera connected with a personal computer with dedicated software (AnalySIS, Soft Imaging Software, Muenster, Germany) [21]. Results of electron microscopy studies were compared with those obtained by analyzing 3 randomly selected wild-type (wt) PHEO (Table 1, [22]).…”