Widefield Optical Imaging of Changes in Uptake of Glucose and Tissue Extracellular pH in Head and Neck Cancer

Abstract

The overall objective of this study is to develop an optical imaging approach to simultaneously measure altered cell metabolism and changes in tissue extracellular pH with the progression of cancer using clinically isolated biopsies. In this study, 19 pairs of clinically normal and abnormal biopsies were obtained from consenting head and neck cancer patients at UCDMC. Fluorescence intensity of tissue biopsies before and after topical delivery of 2-NBDG (2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxy-D-glucose) and Alexa 647-pHLIP (pH (low) insertion peptide) was measured non-invasively by widefield imaging, and correlated with pathological diagnosis. The results of widefield imaging of clinical biopsies demonstrated that 2-NBDG and pHLIP peptide can accurately distinguish the pathologically normal and abnormal biopsies. The results also demonstrated the potential of this approach to detect sub-epithelial lesions. Topical application of the contrast agents generated a significant increase in fluorescence contrast (3–4 fold) in the cancer biopsies as compared to the normal biopsies, irrespective of the patient and location of the biopsy within a head and neck cavity. This unpaired comparison across all the cancer patients in this study highlights the specificity of the imaging approach. Furthermore, the results of this study indicated that changes in intracellular glucose metabolism and cancer acidosis are initiated in the early stages of cancer and these changes are correlated with the progression of the disease. In conclusion, this novel optical molecular imaging approach to measure multiple biomarkers in cancer has a significant potential to be a useful tool for improving early detection and prognostic evaluation of oral neoplasia.

Novel application of complementary imaging techniques to examine in vivo glucose metabolism in the kidney

“…Consequently, we used intravital MPM to monitor the cellular uptake of the fluorescent glucose analog 2-NBDG as a complement to PET for examining cellular glucose tracer uptake in the living animal. Similar to 18 F-FDG in PET, 2-NBDG in optical microscopy has experienced growing application for both preclinical and clinical studies of cancer (8,16,21). Our findings with 2-NBDG and intravital MPM in the proximal tubule of rodents were parallel to our findings with 18 F-FDG and PET in the cortex of the kidney.…”

“…In this study, we employed positron emission tomography (PET) and intravital multiphoton microscopy (MPM) to assess cortical and proximal tubule glucose tracer uptake, respectively, following experimental perturbations of kidney metabolism. Applying dynamic image acquisition PET with [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] fluoro-2-deoxyglucose ( 18 F-FDG) and tracer kinetic modeling, we found that an intracellular compartment in the cortex of the kidney could be distinguished from the blood and urine compartments in animals. Given emerging literature that the tumor suppressor protein p53 is an important regulator of cellular metabolism, we demonstrated that PET imaging was able to discern a threefold increase in cortical 18 F-FDG uptake following the pharmacological inhibition of p53 in animals.…”

Targeted imaging of urothelium carcinoma in human bladders by an ICG pHLIP peptide ex vivo

“…bladder cancer | fluorescence-guided surgery | NIR imaging | acidity | human tissue B ladder cancer is the fifth most common cancer, constituting 4.5% of all new cancer cases in the United States; 76,960 new cases were estimated in 2016, and the death rate currently expected from bladder cancer is 21% (16,390). Approximately 2.4% of men and women will be diagnosed with bladder cancer at some point during their lifetime.…”

“…pH low insertion peptides (pHLIPs) are a class of membrane-binding peptides that specifically target acidic cells in vitro and in vivo (11) by inserting across cellular membranes when the extracellular pH is low (12). pHLIPs conjugated with fluorescent dyes have been used to differentiate normal from neoplastic tissue in various animal tumor models (12)(13)(14)(15) and in human biopsy head and neck samples (16,17). This report uses an indocyanine green (ICG) pHLIP conjugate for the diagnosis of urothelial carcinoma and precancerous lesions in fresh human radical cystectomy samples ex vivo and points the way toward a wide range of diagnostic and therapeutic alternatives.…”

The pH low insertion peptide pHLIP Variant 3 as a novel marker of acidic malignant lesions

“…Clinical applications have focused on the topical application of pHLIP onto biopsies from human head and neck cancer patients, where pHLIP detected cancerous tissue within the samples (46,47).…”