Metabolic Reprogramming of Ovarian Cancer Spheroids during Adhesion

Compton, Stephanie L. E.; Grieco, Joseph P.; Gollamudi, Benita; Bae, Eric; Mullekom, Jennifer H. Van; Schmelz, Eva M.

doi:10.3390/cancers14061399

Cited by 8 publications

(14 citation statements)

References 62 publications

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“…Mitochondrial respiration was very low in the spheroids confirming our previously published observations ( 10 , 14 ). While the increase over time in the limiting culture conditions was statistically significant, it is unclear if these small changes are physiologically relevant.…”

Section: Resultssupporting

confidence: 91%

“…This suggests that the cells from the outer layers of the spheroids are actively proliferating upon adhesion; the flattening of the spheroids can generate a larger adhesion layer that allows for the re-organization of mitochondria. This agrees well with our previous observations that glucose uptake was only drastically increased in the adherent spheroid cells and their outgrowth ( 14 ) and indicates that the fragmented mitochondrial phenotype is indeed reversible after adhesion.…”

Section: Discussionsupporting

confidence: 93%

“…Even short-term adhesion alters cellular metabolism ( 14 ), suggesting that the mitochondrial phenotype observed in the spheroids -fragmented with very low respiration- is reversible upon adhesion. Here we mimicked early secondary metastatic outgrowth conditions and investigated if differential mitochondrial plasticity is supporting the adaptation to changing culture conditions that may contribute to the differing metastatic capacity of MOSE-L and MOSE-L TIC v cells.…”

Section: Resultsmentioning

confidence: 99%

“…Aggregation of the cancer cells was accompanied by a fragmented mitochondrial phenotype especially in the core of our spheroid models ( 13 ) resulting in a drastic reduction of respiration ( 10 ) as well as increased mitophagic signaling but not an induction of apoptosis (Grieco et al., under review). We have further shown a change in cellular metabolism in the earliest stages of spheroid adhesion ( 14 ), suggesting that successful ovarian metastases can adapt to the changing conditions they are exposed to from exfoliation, dissemination, secondary site attachment to invasion and induction of angiogenesis without loss of viability.…”

Section: Introductionmentioning

confidence: 87%

“…Prior to experimental procedures, the cellular media was replaced to serum- and bicarbonate-free medium. Oxygen consumption rate (OCR) measurements including basal, maximum respiration, spare-respiratory capacity, ATP synthesis, proton leak, and non-mitochondrial respiration were obtained and calculated as previously described ( 10 , 14 ). Spheroid respiration measurement cycles consisted of 3 min mixing, 2 min wait, and 3min measurement cycles.…”

Section: Methodsmentioning

confidence: 99%

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Mitochondrial plasticity supports proliferative outgrowth and invasion of ovarian cancer spheroids during adhesion

et al. 2023

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BackgroundOvarian cancer cells aggregate during or after exfoliation from the primary tumor to form threedimensional spheroids. Spheroid formation provides a survival advantage during peritoneal dissemination in nutrient and oxygen-depleted conditions which is accompanied by a suppressed metabolic phenotype and fragmented mitochondria. Upon arrival to their metastatic sites, spheroids adhere to peritoneal organs and transition to a more epithelial phenotype to support outgrowth and invasion. In this study, we investigated the plasticity of mitochondrial morphology, dynamics, and function upon adhesion.MethodsUsing our slow-developing (MOSE-L) and fast-developing (MOSE-LTICv) ovarian cancer models, we mimicked adhesion and reoxygenation conditions by plating the spheroids onto tissue culture dishes and changing culture conditions from hypoxia and low glucose to normoxia with high glucose levels after adhesion. We used Western Blot, microscopy and Seahorse analyses to determine the plasticity of mitochondrial morphology and functions upon adhesion, and the impact on proliferation and invasion capacities.ResultsIndependent of culture conditions, all spheroids adhered to and began to grow onto the culture plates. While the bulk of the spheroid was unresponsive, the mitochondrial morphology in the outgrowing cells was indistinguishable from cells growing in monolayers, indicating that mitochondrial fragmentation in spheroids was indeed reversible. This was accompanied by an increase in regulators of mitobiogenesis, PGC1a, mitochondrial mass, and respiration. Reoxygenation increased migration and invasion in both cell types but only the MOSE-L responded with increased proliferation to reoxygenation. The highly aggressive phenotype of the MOSE-LTICv was characterized by a relative independence of oxygen and the preservation of higher levels of proliferation, migration and invasion even in limiting culture conditions but a higher reliance on mitophagy. Further, the outgrowth in these aggressive cells relies mostly on proliferation while the MOSE-L cells both utilize proliferation and migration to achieve outgrowth. Suppression of proliferation with cycloheximide impeded aggregation, reduced outgrowth and invasion via repression of MMP2 expression and the flattening of the spheroids.DiscussionOur studies indicate that the fragmentation of the mitochondria is reversible upon adhesion. The identification of regulatory signaling molecules and pathways of these key phenotypic alterations that occur during primary adhesion and invasion is critical for the identification of druggable targets for therapeutic intervention to prevent aggressive metastatic disease.

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Section: Resultssupporting

confidence: 91%

Section: Discussionsupporting

confidence: 93%

Section: Resultsmentioning

confidence: 99%