\u03b2-Galactosidase is a target enzyme for detecting peritoneal metastasis of gastric cancer

Hidemasa Kubo,Yasutoshi Murayama,Takuma Ohashi,Masayuki Yubakami,Kazuma Okamoto,Mako Kamiya,Eigo Otsuji,Soichiro Ogawa,Tatsuya Matsumoto,Yasuteru Urano,Takeshi Kubota

doi:10.1038/s41598-021-88982-2

Abstract

Diagnosis of peritoneal metastasis in gastric cancer (GC) is essential for determining appropriate therapeutic strategies and avoiding non-essential laparotomy or gastrectomy. Recently, a variety of activatable fluorescence probes that can detect enzyme activities have been developed for cancer imaging. The aim of this study was to identify the key enzyme involved in peritoneal metastasis in GC. The enzymatic activity of gamma-glutamyl transpeptidase, dipeptidyl peptidase IV, and β-galactosidase (β-Gal) was assessed in lysates prepared from preserved human GC (n = 89) and normal peritoneal (NP; n = 20) samples. β-Gal activity was significantly higher in the human GC samples than in NP samples, whereas no differences were observed in the activities of the other enzymes. Therefore, we used SPiDER-βGal, a fluorescent probe that can be activated by β-Gal, for imaging GC cell lines, peritoneal metastasis in a mouse model, and fresh human resected GC samples (n = 13). All cell lines showed fluorescence after applying SPiDER-βGal, and metastatic nodules in the mice gradually developed high fluorescence that could be visualized with SPiDER-βGal. The human GC samples showed significantly higher fluorescence than NP samples. β-Gal is a useful target enzyme for fluorescence imaging of peritoneal metastasis in GC.

Highlights

Diagnosis of peritoneal metastasis in gastric cancer (GC) is essential for determining appropriate therapeutic strategies and avoiding non-essential laparotomy or gastrectomy
We revealed that the β-Gal activity in GC is significantly higher than that of the normal peritoneal (NP), suggesting the potential of β-Gal to serve as a target enzyme for the development of an activatable fluorescence probe for imaging peritoneal metastasis in GC
We confirmed that SPiDER-βGal is useful for sample imaging of GC using fluorescence imaging of GC cell lines, a mouse model of peritoneal metastasis, and fresh human GC samples

Summary

Introduction

Diagnosis of peritoneal metastasis in gastric cancer (GC) is essential for determining appropriate therapeutic strategies and avoiding non-essential laparotomy or gastrectomy. A variety of activatable fluorescence probes that can detect enzyme activities have been developed for cancer imaging. The enzymatic activity of gamma-glutamyl transpeptidase, dipeptidyl peptidase IV, and β-galactosidase (β-Gal) was assessed in lysates prepared from preserved human GC (n = 89) and normal peritoneal (NP; n = 20) samples. We used SPiDER-βGal, a fluorescent probe that can be activated by β-Gal, for imaging GC cell lines, peritoneal metastasis in a mouse model, and fresh human resected GC samples (n = 13). A variety of activatable fluorescence probes targeting cancer-associated enzymes have been d eveloped[13,14,15]. It is important to select specific target enzymes for each cancer type according to its upregulated expression in the cancer tissue compared with that in the surrounding normal tissue to achieve specific fluorescence imaging

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