br Fig S indicating that aptamer PDGC
(Fig. S2), indicating that aptamer PDGC21-T has strong binding and recognition ability for clinical GC tissues. In addition, no positive staining was observed using the ssDNA library for GC tissues or corre-sponding adjacent tissues, indicating that the PDGC21-T-QD probe is highly specific to GC cells. More important, we observed that the fluorescence intensity of poorly differentiated GC tissues was stronger than that of well/moderately differentiated GC tissues (Fig. 5B). Fur-ther, we performed a scanning quantitative analysis to confirm the fluorescent intensity in the GC tissue samples. As shown in Fig. 5C, for the same patient, the fluorescence signal of the GC tissue was sig-nificantly higher than that of the adjacent tissue; in addition, almost every case of poorly differentiated GC tissue exhibited a strong fluor-escence signal, and the mean fluorescence intensity was significantly higher than that of well/moderately differentiated GC tissues. These results further suggest that aptamer PDGC21-T is highly specific to poorly differentiated GC tissues and has potential as a specific mole-cular probe for the targeted imaging of poorly differentiated GC.
In summary, we used subtractive Cell-SELEX technology to screen and identify aptamer PDGC21, which exhibited excellent binding affi-nity to poorly differentiated GC BGC-823 cells. The truncated aptamer PDGC21-T displayed a higher affinity to the target BGC-823 PD98059 compared with the full length aptamer PDGC21, with a lower Kd value. Changes in temperature did not change the binding of aptamer PDGC21-T to BGC-823 cells. In addition, aptamer PDGC21-T not only specifically bound to poorly differentiated GC cell lines but also bound to a poorly differentiated CRC cell line, indicating a superior differ-entiation specificity compared with other reported aptamers. When combined with fluorescent nanoparticle QDs, the PDGC21-T-QD probe distinguished poorly differentiated GC cells from other cells not only in mixed culture cells but also in clinical specimens. Moreover, the PDGC21-T-QD probe displayed higher fluorescence intensity with poorly differentiated GC tissues, suggesting that aptamer PDGC21-T could be developed into a promising molecular probe to indicate treatment direction and predict outcomes of GC cancer. Given that aptamer PDGC21-T can bind to the target cells even at 37 °C, this ap-tamer can be used for in vivo targeted imaging or targeted delivery of drugs, which will provide new methods for the early diagnosis and therapy of poorly differentiated GC. Additionally, once the target of aptamer PDGC21-T is identified, it will be possible to discover new biomarkers related to GC differentiation.
CRediT authorship contribution statement
Wanming Li: Conceptualization, Methodology, Validation, Formal analysis, Writing - original draft. Shuo Wang: Validation, Software, Formal analysis. Linlin Zhou: Validation, Investigation. Yajie Cheng: Validation, Investigation. Jin Fang: Methodology, Resources, Writing - review & editing, Supervision.
Appendix A. Supporting information
A. Tsuji, Phase Ⅱ study of bolus 5-fluorouracil and leucovorin combined with weekly paclitaxel as first-line therapy for advanced gastric cancer, Oncology 81 (2011) 291–297.
 H.H. Wu, W.C. Lin, K.W. Tsai, Advances in molecular biomarkers for gastric cancer: miRNAs as emerging novel cancer markers, Expert Rev. Mol. Med. 16 (2014) e1.  L.B. Sun, G.J. Zhao, D.Y. Ding, B. Song, R.Z. Hou, Y.C. Li, Comparison between better and poorly differentiated locally advanced gastric cancer in preoperative chemotherapy: a retrospective, comparative study at a single tertiary care institute, World J. Surg. Oncol. 12 (2014) 280.
L. Ramsundar, J. Watari, K. Yokota, H. Tanabe, T. Sato, Y. Kohgo, K.M. Das, Gastric intestinal metaplasia as detected by a monoclonal antibody is highly associated with gastric adenocarcinoma, Gut 52 (2003) 807–812.  J. Watari, N. Chen, P.S. Amenta, H. Fukui, T. Oshima, T. Tomita, H. Miwa, K.J. Lim, K.M. Das, Helicobacter pylori associated chronic gastritis, clinical syndromes, pre-cancerous lesions, and pathogenesis of gastric cancer development, World J.
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An updated European Organisation for Research and Treatment of Cancer (EORTC) protocol for pathological evaluation of sentinel lymph nodes for melanoma
Martin G. Cook a,*,1, Daniela Massi b,1, Anna Szumera-Cieckiewicz c, Joost Van den Oord d, Willeke Blokx e, Le´on C. van Kempen f, Thiagarajah Balamurugan a, Francesca Bosisio d, Senada Koljenovic g, Francesca Portelli b, Alexander C.J. van Akkooi h on behalf of the EORTC Melanoma Group