Introduction K-ras proteins have been found mutated in about 35% of human tumors and appear to be an important factor for tumorigenesis. Its expression correlates with metabolic alterations such as increased glycolysis, glutamine consumption and mitochondrial dysfunction. The decoupling of glucose and glutamine uptake leads to a reprogramming of their metabolism to better support cell proliferation and it represents an interesting target for cancer therapy. Aim of this study is to investigate the metabolic alterations occurring in k-ras transformed fibroblasts in in vivo studies and to monitor response to therapy. Methods nu/nu mice were subcutaneously implanted with 2.5 x 105 k-ras transformed murine NIH3T3 fibroblasts (oncogenic k-ras). Animals performed [18F]FDG- and [18F]FLT-PET studies at several time points starting with a tumor dimension of about 4-5 mm. After PET acquisitions, Thymidine Kinase1 (TK1), ki67 and lactate dehydrogenase A (LDH-A) were evaluated by immunohistochemistry (IHC). After that, in the same model, therapy efficacy of chloroquine (i.p. 50 mg/kg; autophagy inhibitor) and BPTES (i.p. 10 mg/kg; glutaminase inhibitor) alone or in combination were monitored by [18F]FDG- and [18F]FLT-PET before and after 48 hours treatments. Images quantification was expressed as Standardized Uptake Value (SUVmax) and Tumor to Background ratio (T/B). Results All animals injected with oncogenic k-ras fibroblasts develop in few days fast growing, aggressive and highly glycolytic tumors that appear homogeneous for both [18F]FDG and [18F]FLT SUV values. Between 7 and 9 days a significant increase in [18F]FDG uptake was observed which remained stable at 13 days. IHC analysis confirmed the high aggressiveness of this cell line. After 48 h chloroquine and BPTES combined treatment, no differences in [18F]FDG and [18F]FLT uptake were observed which were confirmed by tumor volume measurements. Conclusions K-Ras transformed fibroblasts give rise to aggressive and fast-growing tumors which is possible to monitor using PET imaging. Probably, the high aggressiveness of this cell line needs higher dose of BPTES to block glutamine pathway. Acknowledgement This study was supported by Sysbionet, (Italian Research Infrastructures of the Italian ESFRI roadmap).
Assessing glutamine cancer metabolic remodelling in an animal model using PET imaging
Valtorta Silvia;Gaglio Daniela;Belloli Sara;Di Grigoli Giuseppe;Ripamonti Marilena;Todde Sergio;Moresco Rosa Maria
2015
Abstract
Introduction K-ras proteins have been found mutated in about 35% of human tumors and appear to be an important factor for tumorigenesis. Its expression correlates with metabolic alterations such as increased glycolysis, glutamine consumption and mitochondrial dysfunction. The decoupling of glucose and glutamine uptake leads to a reprogramming of their metabolism to better support cell proliferation and it represents an interesting target for cancer therapy. Aim of this study is to investigate the metabolic alterations occurring in k-ras transformed fibroblasts in in vivo studies and to monitor response to therapy. Methods nu/nu mice were subcutaneously implanted with 2.5 x 105 k-ras transformed murine NIH3T3 fibroblasts (oncogenic k-ras). Animals performed [18F]FDG- and [18F]FLT-PET studies at several time points starting with a tumor dimension of about 4-5 mm. After PET acquisitions, Thymidine Kinase1 (TK1), ki67 and lactate dehydrogenase A (LDH-A) were evaluated by immunohistochemistry (IHC). After that, in the same model, therapy efficacy of chloroquine (i.p. 50 mg/kg; autophagy inhibitor) and BPTES (i.p. 10 mg/kg; glutaminase inhibitor) alone or in combination were monitored by [18F]FDG- and [18F]FLT-PET before and after 48 hours treatments. Images quantification was expressed as Standardized Uptake Value (SUVmax) and Tumor to Background ratio (T/B). Results All animals injected with oncogenic k-ras fibroblasts develop in few days fast growing, aggressive and highly glycolytic tumors that appear homogeneous for both [18F]FDG and [18F]FLT SUV values. Between 7 and 9 days a significant increase in [18F]FDG uptake was observed which remained stable at 13 days. IHC analysis confirmed the high aggressiveness of this cell line. After 48 h chloroquine and BPTES combined treatment, no differences in [18F]FDG and [18F]FLT uptake were observed which were confirmed by tumor volume measurements. Conclusions K-Ras transformed fibroblasts give rise to aggressive and fast-growing tumors which is possible to monitor using PET imaging. Probably, the high aggressiveness of this cell line needs higher dose of BPTES to block glutamine pathway. Acknowledgement This study was supported by Sysbionet, (Italian Research Infrastructures of the Italian ESFRI roadmap).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
