Inhibitor Of GLUT1 As A Novel Fluorescent Probe For Selective Tumor Diagnosis

Cancer is a very aggressive disease with biological characteristics such as cell differentiation,abnormal proliferation,uncontrolled growth,invasion,and metastasis.In recent years,cancer morbidity and mortality have remained high.Early diagnosis and treatment can increase the survival rate to 90%,which is of great significance for cancer treatment.However,the size of precancerous lesions is small and morphologically atypical.It is difficult to identify the lesions with the naked eye,so the development of technologies that can indicate tumors and healthy tissues is particularly important for accurately identifying diseased tissues.With the development of imaging equipment engineering and imaging probe chemistry,in vivo medical imaging has made great progress in locating and distinguishing tumor lesions.Fluorescence biological imaging technology,as one of the optical imaging technologies,can provide molecular information of tumor tissues related to tumor anatomy and metabolism,and has the characteristics of low cost,non-radioactivity,easy to use,etc.Therefore,it has been widely used for biological research,pharmaceutical research,and clinical applications.At present,to accelerate the accurate diagnosis of tumors and the personalized treatment of cancer,diagnostic agents based on small-molecule fluorescent probes have become the popular chemical diagnosis and treatment drug because the following reasons: 1)They are generally able to visualize specific organelles and entire animals in living cells;2)They have improved photophysical properties compared to nanocarrier diagnostic agents;3)They can be easily synthesized through chemical modification.In 1930,Warburg first describe increased uptake and metabolism of glucose in cancer cells.Overexpression of glucose transporters,especially GLUT1,is associated with several types of human malignancies.Based on the precision medicine concept,specific biomarkers have become urgent for patient selection and personalized targeted treatment decisions.Over the past two decades,FDG PET imaging has been widely applied for tumor diagnosis and become the standard of care in cancer patients’ baseline staging.But FDG PET still has many technical and logistical problems including high costing,radioactive wasting,and biohazard.Such disadvantages led to the development of novel non-isotopic and more convenient probes.A fluorescent glucose analog of 2-deoxyglucose,2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxy-D-glucose(2-NBDG),is used as a fluorescent tracer to trace glucose uptake and metabolism.Identical to the mechanism of FDG,2-NBDG has been shown by mass spectrometry to undergo the same process of phosphorylation at the C-6 position.2-NBDG represents certain obvious advantages over FDG including its non-radioactivity,relatively low cost,and high sensitivity(at single-cell level).However,as a fluorescent substrate,2-NBDG also demonstrates several drawbacks,such as rapid fluorescence decay,weak signal intensity,high treatment dose,and incompatibility in physiological conditions.Therefore,novel high fluorescence intensity and physiological compatibility fluorescence probes are urgently needed for a breakthrough in cancer therapy.Here we propose a GLUT1 inhibitor WZB-117-conjugated fluorophore for GLUT1-mediated in vitro and in vivo cancer theranostics and develop an image-based,quantitative,single-cell high-throughput cancer agents screening system for the assessment of glucose uptake in normal and tumor cells.Compound WZB-117 has been reported to inhibit glucose transport and cancer cell growth using a glucose deprivation-like mechanism through downregulating glucose transporter 1(GLUT1).Its inhibitory activity was greater than most of the other GLUT1-inhibitory agents reported,such as fasentin and phloretin,which were also shown to be effective in reducing cancer cell growth.We designed and synthesized a series of WZB-117-based original fluorescent bioprobes by coupling various linkers to the 7,8-dihydric position of daphnetin fluorophore,due to its strong fluorescence signal,near-infrared spectrum,high compatibility with biological systems.This is a ground-breaking study to try combining GLUT1 inhibitor with fluorophore.We aimed in this study to develop an image-based,quantitative,high resolution,tumor-targeted cancer diagnosis and treatment therapy using the natural,non-radioactive WZB-117 analog,and to establish a high-throughput drug screen system for quantitative assessment of fluorescence in cancer cells using this theranostic agent.