[Corrigendum] 7­Difluoromethoxyl­5,4'­di­n­octyl genistein inhibits the stem­like characteristics of gastric cancer stem­like cells and reverses the phenotype of epithelial­mesenchymal transition in gastric cancer cells.

Subsequently to the publication of the above article, an interested reader drew to the authors' attention that there appeared to be two pairs of images in Fig. 2A and B on p. 1159 and Fig. 4 on p. 1161 that contained overlapping sections, such that these figures, which were intending to show the results from differently performed experiments, may have been derived from the same original sources. The authors have examined their original data, and realize that, although Fig. 2 was correct as presented in the article, these data were erroneously and inadvertently included in Fig. 4. The revised version of Fig. 4, which shows the inhibition of sphere­forming ability by 7­difluoromethoxyl­5,4'­di­n­octyl genistein (DOFG) in gastric cancer stem­like cells derived from SGC­7901 cells, is shown below, now including the correct data for the panels showing treatment with 0 and 1.0 µmol/l DOFG, and with re­quantification of these data. The authors are grateful to the Editor of Oncology Reports for allowing them the opportunity to publish a Corrigendum, and all the authors agree with its publication. Furthermore, they apologize to the readership for any inconvenience caused. [Oncology Reports 36: 1157­1165, 2016; DOI: 10.3892/or.2016.4848].

The Effect of hsa-miR-451b Knockdown on Biological Functions of Gastric Cancer Stem-Like Cells.

Numerous researches have extensively studied factors such as microRNAs that lead to cancer. Thus, the current study's purpose is to investigate the biological consequences of hsa-miR-451b inhibition on the properties and functions of gastric cancer stem-like cells. First, gastric cancer stem-like cells were transfected by hsa-miR-451b inhibitor then we used real-time RT-PCR to evaluate its effect on the expression of hsa-miR-451b and two of its direct target genes, Stemness markers such as KLF4, SOX2, CD44, OCT3/4 and NANOG genes and finally Akt, PI3K, Bcl-2, Bax, CASP3 and PCNA genes involved in apoptosis. Here, we conducted a DNA Laddering assay to investigate apoptosis. The level of the MMP-2 and -9 Activities and Migration were examined by Zymography and Transwell invasion assay. HUVEC cells were used to investigate angiogenesis. The outcomes revealed that the level of the MMP-2 and -9 Activities, migration and angiogenesis decreased, but apoptosis was induced by inhibiting hsa-miR-451b. Evaluating KREMEN1 and CASK expression showed that the former increased, and the latter dropped under hsa-miR-451b inhibition. Also, upregulation of the KLF4 and SOX2 and downregulation of the CD44, OCT3/4, and NANOG decreased Self-renewal ability of gastric cancer stem cells under hsa-miR-451b inhibition. Even, under hsa-miR-451b inhibition, downregulation of Akt, PI3K, Bcl-2 and PCNA as well as upregulation of Bax and CASP3 revealed a movement towards apoptosis in MKN-45 stem-like cells. In summary, hsa-miR-451b is an oncomir in the carcinogenesis of gastric cancer stem-like cells and may be suggested as an appropriate therapeutic target for future gastric cancer treatment.

Targeting MAD2 modulates stemness and tumorigenesis in human Gastric Cancer cell lines.

Rationale: Gastric cancer (GC) is a solid tumor that contains subpopulations of cancer stem cells (CSCs), which are considered drivers of tumor initiation and metastasis; responsible for therapeutic resistance; and promoters of tumor relapse. The balance between symmetric and asymmetric division is crucial for stem cell maintenance. The objective of this study is to evaluate the role of MAD2, a key protein for proper mitotic checkpoint activity, in the tumorigenesis of GC. Methods: Gastric cancer stem cells (GCSCs) were obtained from MKN45, SNU638 and ST2957 cell lines. Pluripotency and stemness markers were evaluated by RT-qPCR and autofluorescence and membrane markers by flow cytometry. Relevant signal transduction pathways were studied by WB. We analysed cell cycle progression, migration and invasion after modulation of MAD2 activity or protein expression levels in these in vitro models. In vivo assays were performed in a nude mouse subcutaneous xenograft model. Results: We found that NANOG, CXCR4 and autofluorescence are common and consistent markers for the GCSCs analysed, with other markers showing more variability. The three main signalling pathways (Wnt/ß-catenin; Hedgehog and Notch) were activated in GCSCs. Downregulation of MAD2 in MKN45CSCs decreased the expression of markers CXCR4, CD133, CD90, LGR5 and VIM, without affecting cell cycle profile or therapy resistance. Moreover, migration, invasion and tumor growth were clearly reduced, and accordingly, we found that metalloprotease expression decreased. These results were accompanied by a reduction in the levels of transcription factors related with epithelial-to-mesenchymal transition. Conclusions: We can conclude that MAD2 is important for GCSCs stemness and its downregulation in MKN45CSCs plays a central role in GC tumorigenesis, likely through CXCR4-SNAI2-MMP1. Thus, its potential use in the clinical setting should be studied as its functions appear to extend beyond mitosis.

Xiaotan Sanjie decoction attenuates tumor angiogenesis by manipulating Notch-1-regulated proliferation of gastric cancer stem-like cells.

AIM: To determine the underlying mechanisms of action and influence of Xiaotan Sanjie (XTSJ) decoction on gastric cancer stem-like cells (GCSCs). METHODS: The gastric cancer cell line MKN-45 line was selected and sorted by FACS using the cancer stem cell marker CD44; the stemness of these cells was checked in our previous study. In an in vitro study, the expression of Notch-1, Hes1, Vascular endothelial growth factor (VEGF), and Ki-67 in both CD44-positive gastric cancer stem-like cells (GCSCs) and CD44-negative cells was measured by Western blot. The effect of XTSJ serum on cell viability and on the above markers was measured by MTT assay and Western blot, respectively. In an in vivo study, the ability to induce angiogenesis and maintenance of GCSCs in CD44-positive-MKN-45- and CD44-negative-engrafted mice were detected by immunohistochemical staining using markers for CD34 and CD44, respectively. The role of XTSJ decoction in regulating the expression of Notch-1, Hes1, VEGF and Ki-67 was measured by Western blot and real-time polymerase chain reaction. RESULTS: CD44(+) GCSCs showed more cell proliferation and VEGF secretion than CD44-negative cells in vitro, which were accompanied by the high expression of Notch-1 and Hes1 and positively associated with tumor growth (GCSCs vs CD44-negative cells, 2.72 ± 0.25 vs 1.46 ± 0.16, P < 0.05) and microvessel density (MVD) (GCSCs vs CD44-negative cells, 8.15 ± 0.42 vs 3.83 ± 0.49, P < 0.001) in vivo. XTSJ decoction inhibited the viability of both cell types in a dose-dependent manner in vitro. Specifically, a significant difference in the medium- (82.87% ± 6.53%) and high-dose XTSJ groups (77.43% ± 7.34%) was detected at 24 h in the CD44(+) GCSCs group compared with the saline group (95.42% ± 5.76%) and the low-dose XTSJ group (90.74% ± 6.57%) (P < 0.05). However, the efficacy of XTSJ decoction was reduced in the CD44(-) groups; significant differences were only detected in the high-dose XTSJ group at 48 h (78.57% ± 6.94%) and 72 h (72.12% ± 7.68%) when compared with the other CD44- groups (P < 0.05). Notably, these differences were highly consistent with the Notch-1, Hes1, VEGF and Ki-67 expression in these cells. Similarly, in vivo, XTSJ decoction inhibited tumor growth in a dose-dependent manner. A significant difference was observed in the medium- (1.76 ± 0.15) and high-dose XTSJ (1.33 ± 0.081) groups compared with the GCSCs control group (2.72 ± 0.25) and the low-dose XTSJ group (2.51 ± 0.25) (P < 0.05). We also detected a remarkable decrease of MVD in the medium- (7.10 ± 0.60) and high-dose XTSJ (5.99 ± 0.47) groups compared with the GCSC control group (8.15 ± 0.42) and the low-dose XTSJ group (8.14 ± 0.46) (P < 0.05). Additionally, CD44 expression was decreased in these groups [medium- (4.43 ± 0.45) and high-dose XTSJ groups (3.56 ± 0.31) vs the GCSC control (5.96 ± 0.46) and low dose XTSJ groups (5.91 ± 0.38)] (P < 0.05). The significant differences in Notch-1, Hes1, VEGF and Ki-67 expression highly mirrored the results of XTSJ decoction in inhibiting tumor growth, MVD and CD44 expression. CONCLUSION: Notch-1 may play an important role in regulating the proliferation of GCSCs; XTSJ decoction could attenuate tumor angiogenesis, at least partially, by inhibiting Notch-1.

Sox2 enhances the tumorigenicity and chemoresistance of cancer stem-like cells derived from gastric cancer.

Gastric cancer stem-like cells (GCSCs) have been identified to possess the ability of self-renewal and tumor initiation. However, the mechanisms involved remain largely unknown. Here, we isolated and characterized the GCSCs by side population (SP) sorting procedure and cultured sphere cells (SC) from human gastric cancer cell lines SGC-7901, BGC-823, MGC-803, HGC-27 and MKN-28. The sorting and culture assay revealed that SP cells proliferated in an asymmetric division manner. In addition, SP cells exhibited a higher potential of spheroid colony formation and greater drug resistance than non-SP cells (NSP). Moreover, the SC were found with enhanced capabilities of drug resistance in vitro and tumorigenicity in vivo. Sox2 mRNA and protein was highly and significantly overexpressed in the SP cells and SC. Importantly, downregulation of Sox2 with siRNA obviously reduced spheroid colony formation and doxorubicin efflux, as well as increased apoptosis rate in sphere cells in vitro and suppressed tumorigenicity in vivo. These results suggest that both SP cells and cultured SC enrich with GCSCs and that Sox2 plays a pivotal role in sustaining stem cell properties and might be a potential target for gastric cancer therapy.