To develop imaging biomarkers for tumors aggressiveness, our previous optical redox imaging (ORI) studies of the reduced nicotinamide adenine dinucleotide (NADH) and oxidized flavoproteins (Fp, containing flavin adenine dinucleotide, i.e., FAD) in tumor xenografts of human melanoma associated the high optical redox ratio (ORR = Fp/(Fp + NADH)) and its heterogeneity to the high invasive/metastatic potential, without having reported quantitative results for NADH and Fp. Here, we implemented a calibration procedure to facilitate imaging the nominal concentrations of tissue NADH and Fp in the mouse xenografts of two human melanoma lines, an indolent less metastatic A375P and a more metastatic C8161. Images of the redox indices (NADH, Fp, ORR) revealed the existence of more oxidized areas (OAs) and more reduced areas (RAs) within individual tumors. ORR was found to be higher and NADH lower in C8161 compared to that of A375P xenografts, both globally for the whole tumors and locally in OAs. The ORR in the OA can differentiate xenografts with a higher statistical significance than the global averaged ORR. H&E staining of the tumors indicated that the redox differences we identified were more likely due to intrinsically different cell metabolism, rather than variations in cell density.
为开发肿瘤侵袭性的成像生物标志物，我们先前通过光学氧化还原成像技术对人黑色素瘤异种移植瘤中还原型烟酰胺腺嘌呤二核苷酸（NADH）和氧化型黄素蛋白（Fp，含黄素腺嘌呤二核苷酸即FAD）的研究发现，高光学氧化还原比（ORR = Fp/(Fp + NADH)）及其异质性与高侵袭/转移潜能相关，但未报告NADH和Fp的定量结果。本研究通过建立校准程序，实现了对两种人黑色素瘤细胞系（低转移性A375P与高转移性C8161）小鼠异种移植瘤中NADH和Fp名义浓度的定量成像。氧化还原指标（NADH、Fp、ORR）图像显示单个肿瘤内部存在氧化程度较高区域（OAs）与还原程度较高区域（RAs）。研究发现，无论是在整体肿瘤层面还是在局部OAs区域，C8161异种移植瘤的ORR均高于A375P，而NADH水平则更低。相较于整体平均ORR，OA区域的ORR能以更高的统计学显著性区分不同异种移植瘤。肿瘤H&E染色结果表明，我们发现的氧化还原差异更可能源于细胞代谢的内在差异，而非细胞密度变化所致。
Quantitative Optical Redox Imaging of Melanoma Xenografts with Different Metastatic Potentials
肿瘤(癌症)患者之家