{'fraction_non_alphanumeric': 0.04335551522484372, 'fraction_numerical': 0.014519056261343012, 'mean_word_length': 5.342710997442455, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Antibody microarray‐based technology to rapidly define matrix metalloproteinase (MMP) signatures in patients undergoing resection for primary gastric carcinoma

To the Editor: Early diagnosis is likely to improve the outcome and prognosis of most solid tumors, including biologically aggressive, chemotherapy-refractory gastric carcinomas (GC). Current clinical biomarkers in GC, however, lack the sensitivity and specificity required for screening an asymptomatic population for the purpose of early detection [1]. Moreover, there is an urgent need to develop new approaches aimed to detect and measure biomarkers in tissues and/or blood as a means of identifying GC patients who are more likely to respond to conventional and novel therapies molecularly targeting GC cells and stromal factors [2]. Although the ongoing development of the three mainstream high-throughout proteomic profiling techniques (i.e., gel-based methods, gel-free mass spectrometry [MS]-based methods and surface-enhanced laser desorption/ionization [SELDI] time-offlight [TOF] MS), through application in tissue-based clinical studies, has the potential to facilitate the identification of new and better diagnostic/prognostic biomarkers for GC detection and staging, the requirement of sophisticated devices greatly limits their broad application in routine clinical practice [3–5]. Alternatively, antibody microarray-based technology is a promising tool for the field of oncoproteomics in which one the most important applications is to compare proteome expression signatures of malignant versus normal samples [6–8]. We recently envisioned that innovative, simple, flexible and costeffective antibody-based protein array systems—which can simultaneously detect expression levels of multiple proteins and combine advantages of the specificity of ELISA, sensitivity of enhancedchemiluminiscence, and high-throughout of microspot [9]—could be useful at identifying unique ‘‘oncoproteomic signatures’’ in GC. Given that: (a) GC usually shows extensive local tumor invasion and early spread to metastasis sites; (b) the crucial step in GC development and metastasis is degradation and remodeling of tumor surrounding extracellular matrix (ECM); (c) invasion of GC cells within the basement membrane depends on the balanced activities of matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) [10–16]; and that (d) GC is one of the few cancers for which a significant survival benefit from therapy with a MMP inhibitor has been described [17]; we decided to characterize the profile of MMPs and TIMPs in a pilot study for GC biomarker discovery. To minimize individual variations, we simultaneously evaluated MMPs/TIMPs profiles in GC samples and corresponding non-cancerous gastric mucosae from the same GC patient. Given that MPPs and TIMPs are secreted by both tumor and stromal cells, we used whole cancer tissues including the noncancerous stromal components as starting material for MMPs/TIMPs profiling instead of analyzing pure tumor cells. Twenty paired-samples from 10 GC patients undergoing gastrectomy at our institution were included in the study. Detection of seven MMPs (MMP-1/-2/-3/-8/-9/-10/-13) and three TIMPs (TIMP-1/-2/-4) was simultaneously performed in matched pairs of tumor/normal gastric tissues using the commercially available RayBio Human Matrix Metalloproteinase Antibody Array. Fold-change values for the expression of MMPs and TIMPs were calculated upon quantification of densitometric values of individual MMPs and TIMPs spots in tumor and paired normal tissue. Figure 1A shows representative raw arrays obtained in matched pairs of gastric tumor/normal tissues from three GC patients. Figure 1B (top) summarizes the fold-changes in MMPs/ TIMPs expression obtained for all the paired-samples evaluated in this pilot study. AGC-associated ‘‘MMP/TIMP signature’’ was constructed by considering those MMPs and TIMPs significantly altered in at least 1 GC patient (Fig. 1B, bottom). Upon this approach it was noteworthy that: (a) MMP-9 and MMP-8 were found to be overexpressed ( 5-fold) in 90% (9/10) and 80% (8/10) of GC patients, respectively; (b) TIMP-1 was significantly up-regulated in 70% (7/10) of GC patients whereas TIMP-2 expression was found to be enhanced solely in 2 out of 10 (20%) GC patients; (c) there was a good correlation between the primary MMP/TIMP interactor antigen levels, that is, 75% (6/8) of GC patients co-overexpressed MMP-9 with TIMP-1 while 2 out of 8 GC patients (25%) exhibited drastically enhanced MMP-9/ TIMP-1 ratio. Given that our pilot study involving a small group of patients rapidly and accurately identified a MMP/TIMP signature similarly reported in earlier studies that used more cumbersome, time consuming and/or expensive techniques (e.g., zymography, immunohistochemistry, ELISA, quantitative bioactivity assays [BIAs]) in larger groups of GC patients [10–16], it is reasonable to suggest that antibody