A Bioluminescent Probe for H₂S Detection in Tumor Microenvironment

Hydrogen sulfide (H₂S) is an endogenous gaseous signaling molecule that regulates various physiological functions, and its abnormal levels have been closely linked to the onset and progression of numerous diseases including renal cell carcinoma (RCC). RCC is the most common malignant tumor of the kidney, accounting for 85-90% of all kidney cancer cases. However, studies using H₂S as a biomarker for monitoring RCC progression at the molecular level remain relatively limited. Most current H₂S luminescent probes suffer from low sensitivity and often need external stimuli, such as cysteine, to artificially elevate H₂S levels, thereby reducing their effectiveness in detecting H₂S in cells or in vivo. Although bioluminescent imaging probes are gaining attention for their specificity and high signal-to-noise ratio, no existing probes are specifically designed for detecting H₂S in RCC. Additionally, many bioluminescent probes face challenges such as short emission wavelengths or dependence on complex conditions such as external adenosine triphosphate (ATP). Herein, through "caging" the luciferin substrate QTZ with H₂S recognition groups, a H₂S-sensitive bioluminescent probe QTZ-N₃ with good sensitivity (∼0.19 μM) and selectivity was prepared. QTZ-N₃ can effectively detect endogenous H₂S in 786-O-Nluc renal cancer cells and sensitively monitor H₂S levels in the RCC xenograft nude mouse model without requiring stimuli like cysteine. Furthermore, QTZ-N₃ allows for the real-time monitoring of H₂S during tumor progression. This work lays a solid foundation for future understanding of the biological functions of H₂S in vivo.