Abstract

Background: A high metabolism restructuring of cancerous cells to facilitate proliferation and survival during treatment pressure. However, there is a lack of understanding of processes that promote metabolic flexibility and its role in therapeutic resistance. Objective: The aim of the research is to determine the biochemical basis of metabolic reprogramming in cancer cells and determine metabolic determinants of therapeutic resistance by comprehensive functional studies. Methodology: Multi-platform metabolic profiling of eight cancer cell lines (breast, lung, colorectal, and hepatocarellular) was undertaken by us. Glucose uptake and lactate (produced) and ATP were measured colorimetrically and enzymatically to do metabolic profiling. The glucose-only/glutamine-only substrate switching experiments were used to measure the utilization of carbon sources. The sensitivity of drug screening was conducted using 20 metabolic inhibitors on glycolysis, glutaminolysis and fatty acid production. To determine metabolic flexibility as ATP maintenance during nutrient stress, a new index of metabolic plasticity (MPI) was computed. The ELISA protein expression and enzymatic activity were investigated. Results: The metabolic heterogeneity of cancer cells was at an enormous point with implications on tissues. The glycolytic rates in the cancers were found to be 2.4-4.0-fold higher compared to normal controls (p<0.001), however, its oxygen consumption did not decrease by any margin (1.4-2.0-fold) (p<0.001). Addiction to glutamine was between 57.4 in colorectal and 81.6 in hepatocellular carcinoma. To determine the effect of switching carbon sources, metabolic plasticity of cancer cells was more apparent whereby, the cellular levels of ATP in cancer cells were 71.4+/-5.8 percent under glucose restriction conditions relative to normal 38.7+/-3.6 percent conditions (p<0.001). Drug sensitivity screening showed that glutaminase inhibitors were mostly active (BPTES IC50=12.4+/-3.2 5M)in which hepatocellular carcinoma was the most sensitive. An index of metabolic plasticity fitted well to different classes of inhibitors (r=0.81, p<0.001) to predict resistance to drugs. A new carbon source was adopted by smooth cancer cells in the course of 10-14 hours of incubation as opposed to 20-24 hours of incubation among the less flexible cells. Conclusions: The resistance to cancer therapy occurs due to metabolic flexibility and not to dependence on the specific pathway. The new prediction biomarker of treatment is metabolic plasticity index. These findings support the use of combination therapies which simultaneously attack multiple metabolic networks in order to induce plasticity of cancer cells.