Pioglitazone modulates tumor cell metabolism and proliferation in multicellular tumor spheroids

Abstract

The anti-diabetic thiazolidinedione compound pioglitazone, a peroxisome proliferator-activated receptor-gamma agonist, and selective cyclooxygenase-2 inhibitors are clinically used in patients with advanced malignancies. Several previously published in vivo and in vitro studies showed growth inhibitory effects on different cancer cell lines. However, the underlying mechanisms are fairly unclear. Here, we analyzed the effects of pioglitazone in combination with other drugs in a three-dimensional multicellular tumor spheroid culture system (MCTS) generated from the two prostate carcinoma cell lines PC3 and LNCaP. As expected, pioglitazone also inhibited tumor cell proliferation in the MCTS system. Further studies revealed that pioglitazone lowered the pH of the culture medium, decreased oxygen consumption and increased lactate secretion in both tumor cell lines. Other glitazones, troglitazone and ciglitazone, had similar effects. The combination of pioglitazone with 2-deoxyglucose, a potent inhibitor of glycolysis, had an additive effect on the inhibition of cell proliferation and led to MCTS disintegration. Our data propose a new mechanism of growth inhibition by pioglitazone through modulation of the tumor cell metabolism.

Frequent Gene Products and Molecular Pathways Altered in Prostate Cancer- and Metastasis-Initiating Cells and Their Progenies and Novel Promising Multitargeted Therapies

“…These elements are induced under normoxic or hypoxic conditions and may provide critical functions for PC cell survival, invasion and metastasis; angiogenesis; and/or treatment resistance ( Figure 3) (29,46,47,129,133,140,(146)(147)(148)(211)(212)(213)(214)(215)(216)(217)(218). Consistent with this finding, the inhibition of glycolysis by using 2-deoxy-Dglucose (2-DG), alone or in combination with other anticancer agents such as pioglitazone, a microtubule disruptor, 2-methoxyoestradiol-3,17-O,O-bissulphamate (STX140) or metformin, which acts at least in part by inhibiting 2-DG-induced autophagy, has been shown to induce cytotoxic effects on the highly proliferative PC cells, including multicellular tumor spheroids from metastatic PC cells, and inhibit tumor growth in vivo (Figure 3) (147,148,212,213). It has also been noted that the inhibition of glycolysis by either 2-DG or iodoacetate downregulated P-glycoprotein expression and inhibited the efflux of doxorubicin in multicellular tumor spheroids generated from metastatic and AI DU145 PC cells, suggesting that this therapeutic strategy may be effective for reversing the multidrug resistance phenotype of PC cells (146).…”

“…In fact, an adaptive switch from mitochondrial respiration (oxidative phosphorylation) to an enhanced glycolytic metabolism, known as the Warburg effect, may occur in PC stem/ progenitor cells and their progenies through an upregulated expression of glycolytic enzymes such as phosphoglycerate kinase 1 (Pgk1) that breaks down glucose (141,(145)(146)(147)(148)(149). The enhanced glycolysis may contribute to provide the energy and nutrients necessary for the sustained proliferation and the biosynthesis of new cellular components, including proteins and lipids, in rapidly dividing PC cells (141,(145)(146)(147)(148)(149).…”

Troglitazone Stimulates Cancer Cell Uptake of 18F-FDG by Suppressing Mitochondrial Respiration and Augments Sensitivity to Glucose Restriction

“…In the study of Friday et al (9), withdrawal of glucose from the medium attenuated the ability of troglitazone to stimulate lactate release in breast cancer cells. Furthermore, Gottfried et al (15) demonstrated that pioglitazone-mediated suppression of prostate cancer cell proliferation was enhanced by the combined inhibition of hexokinase activity with 2-deoxyglucose.…”

“…Rosiglitazone (Cayman Chemical) was previously shown to increase 18 F-FDG uptake in tumor cells (14). A more recent study on prostate cancer cells showed that glitazone-induced suppression of proliferation was accompanied by stimulation of glycolysis and reduced oxygen consumption (15). In another recent study, breast cancer cells treated with troglitazone showed an acute increase of glycolysis with reduced MMP (9).…”

Biosensor-Expressing Spheroid Cultures for Imaging of Drug-Induced Effects in Three Dimensions

“…In the current literature, effects of anticancer compounds in MCTS are commonly monitored in endpoint mode, either by signal integration over one spheroid or microplate cavity, 7 by flow cytometry subsequent to spheroid disintegration, 8 or by immunofluorescence/immunohistochemistry techniques subsequent to spheroid fixation. 9 Whereas such approaches provide quantitative data about averaged responses within the whole spheroid, a spatial and/or temporal resolution of the effects is lacking.…”