The Reverse Warburg Effect and ¹⁸F-FDG Uptake in Non–Small Cell Lung Cancer A549 in Mice: A Pilot Study

Abstract

The purpose of this study was to observe the effect of fasting and feeding on 18 F-FDG uptake in a mouse model of human non-small cell lung cancer. Methods: In in vivo studies, 18 F-FDG small-animal PET scans were acquired in 5 mice bearing non-small cell lung cancer A549 xenografts on each flank with continuous feeding and after overnight fasting to observe the changes in intratumoral distribution of 18 F-FDG and tumor 18 F-FDG standardized uptake value (SUV). In ex vivo studies, intratumoral spatial 18 F-FDG distribution assessed by autoradiography was compared with the tumor microenvironment (including hypoxia by pimonidazole and stroma by hematoxylin and eosin stain). Five overnight-fasted mice and 5 fed mice with A549 tumors were observed. Results: Small-animal PET scans were obtained in fed animals on day 1 and in the same animals after overnight fasting; the lapse was approximately 14 h. Blood glucose concentration after overnight fasting was not different from fed mice (P 5 0.42), but body weight loss was significant after overnight fasting (P 5 0.001). Intratumoral distribution of 18 F-FDG was highly heterogeneous in all tumors examined, and change in spatial intratumoral distribution of 18 F-FDG between 2 sets of PET images from the same mouse was remarkably different in all mice. Tumor 18 F-FDG mean SUV and maximum SUV were not significantly different between fed and fasted animals (all P . 0.05, n 5 10). Only tumor mean SUV weakly correlated with blood glucose concentration (R 2 5 0.17, P 5 0.03). In ex vivo studies, in fasted mice, there was spatial colocalization between high levels of 18 F-FDG uptake and pimonidazole-binding hypoxic cancer cells; in contrast, pimonidazole-negative normoxic cancer cells and noncancerous stroma were associated with low 18 F-FDG uptake. However, high 18 F-FDG uptake was frequently observed in noncancerous stroma of tumors but rarely in viable cancer cells of the tumors in fed animals. Conclusion: Host dietary status may play a key role in intratumoral distribution of 18 F-FDG. In the fed animals, 18 F-FDG accumulated predominantly in noncancerous stroma in the tumors, that is, reverse Warburg effect. In contrast, in fasted status, 18 F-FDG uptake was found in hypoxic cancer cells component (Pasteur effect). Our findings may provide a better understanding of competing cancer glucose metabolism hypotheses: the Warburg effect, reverse Warburg effect, and Pasteur effect.

Glycobiology Modifications in Intratumoral Hypoxia: The Breathless Side of Glycans Interaction

“…In lung cancer cells (A549), Zhang et al observed that the uptake of fluorodeoxyglucose (F-FDG), a glucose analogue, is increased in regions stained with pimonidazole, and is stimulated by nutritional deprivation, showing that metabolic utilization of glucose is higher in hypoxic and staring regions [58]. The Warburg and Pasteur effects were observed in diverse melanoma cells lines.…”

Revisit 18F-fluorodeoxyglucose oncology positron emission tomography: “systems molecular imaging” of glucose metabolism

“…Growing evidence indicated that intratumoral 18 F-FDG distribution is heterogeneous and microenvironment dependent. Hypoxic cancer cells had significantly higher 18 F-FDG uptake than oxic cancer cells in in vitro studies [22–25] and in vivo animal studies [8–12, 26, 27], hence, 18 F-FDG accumulation in cancer can not be reasonably explained by Warburg effect.…”

“…Although Pasteur effect seems more frequently apply in microbiology, it oncology application is less popular. In fact, 18 F-FDG accumulation is found significant higher in hypoxic cancer cells than in well oxygenated ones, which may be explained by Pasteur effect [8–12]. …”

“…They claimed the Warburg effect actually took place in tumor associated fibroblasts, and not in cancer cells [16–20]. Zhang et al have examined the hypothesis in cancer cells growing in nude mice with 18 F-FDG PET study [8]. …”

Is Carbonic Anhydrase IX a Validated Target for Molecular Imaging of Cancer and Hypoxia?

“…Results from scintigrams of the abdomen of the patient either 5 days after injection of 111 In-cG250 or 5 days after injection of 131 I-cG250, showed no apparent accumulation of radiolabeled cG250 in tumors. Immunohistochemical analyses revealed the expression of CAIX in tumor tissues of all three Figure 5) [21,[73][74][75][76]. In addition, hypoxic portion of colorectal cancer HCT-8 xenografts had increased 18 F-FDG accumulation [21], but CAIX expression in hypoxic zones was undetectable by immunohistochemistry [36].…”