Improving the tumor selectivity of T cell engagers by logic-gated dual tumor-targeting.

Targeting single tumor antigens makes it difficult to provide sufficient tumor selectivity for T cell engagers (TCEs), leading to undesirable toxicity and even treatment failure, which is particularly serious in solid tumors. Here, we designed novel trispecific TCEs (TriTCEs) to improve the tumor selectivity of TCEs by logic-gated dual tumor-targeting. TriTCE can effectively redirect and activate T cells to kill tumor cells (∼18 pM EC50) by inducing the aggregation of dual tumor antigens, which was ∼70- or 750- fold more effective than the single tumor-targeted isotype controls, respectively. Further in vivo experiments indicated that TriTCE has the ability to accumulate in tumor tissue and can induce circulating T cells to infiltrate into tumor sites. Hence, TriTCE showed a stronger tumor growth inhibition ability and significantly prolonged the survival time of the mice. Finally, we revealed that this concept of logic-gated dual tumor-targeted TriTCE can be applied to target different tumor antigens. Cumulatively, we reported novel dual tumor-targeted TriTCEs that can mediate a robust T cell response by simultaneous recognition of dual tumor antigens at the same cell surface. TriTCEs allow better selective T cell activity on tumor cells, resulting in safer TCE treatment.

Long noncoding RNA SPRY4-IT1 acts as a miR-101-5p sponge to promote gastrointestinal stromal tumor progression by inhibiting ZEB1.

OBJECTIVES: Research on long noncoding RNAs (lncRNAs) has been conducted in different areas of oncology. Currently, the biological significance of lncRNAs and their regulatory features in gastrointestinal stromal tumors (GIST) remain largely unknown. We have previously identified SPRY4-IT1 overexpression in GIST through lncRNA sequencing of GIST tissues. Coincidentally, SPRY4-IT1 is an intron of the SPRY4 gene, and SPRY4 is specifically highly expressed in GIST. Thus the aim of the present study was to investigate the role of lncRNA SPRY4-IT1 in GIST pathogenesis. METHODS: Herein, we screened for SPRY4-IT1 and analyzed its possible phenotypes using Gene set enrichment analysis (GSEA). The phenotypes of GIST were verified using CCK-8, colony formation, and wound-healing assays. The ceRNA mechanism was determined by the location of lncRNA SPRY4-IT1, and its relationship to the Ago2 protein. The SPRY4-IT1/miR-101-5p/ZEB1 axis was predicted using online software and sequencing. Luciferase and pull-down assays were performed for verification. Pathway-associated and phenotype-associated proteins were detected by western blotting. RESULTS: Sequencing analysis revealed 117 differentially expressed lncRNAs in GIST and normal gastric tissue samples. Accordingly, SPRY4-IT1 was screened out and its phenotype was predicted by GSEA. Mechanistically, SPRY4-IT1 was identified as a competing endogenous RNA (ceRNA) that downregulated miR-101-5p and upregulated ZEB1, which activated extracellular signal-regulated kinase (ERK) signaling to stimulate GIST proliferation, invasion, and epithelial-mesenchymal transition. Although this effect was regulated by a negative feedback loop through SPRY4, it was still controlled by SPRY4-IT1. CONCLUSIONS: In GIST, we revealed a ceRNA mechanism by which SPRY4-IT1 modulates ZEB1 by sponging miR-101-5p, eventually driving tumor cell proliferation, migration, and epithelial-mesenchymal transition (EMT).

[A model for the evaluation of groundwater ecological compensation budget]. / åœ°ä¸‹æ°´ç”Ÿæ€è¡¥å¿æ ‡å‡†æ ¸ç®—æ¨¡åž‹.

Groundwater, one of the important water resources, plays an important role in maintaining sustainable social and economic development. The ecological compensation of groundwater is a beneficial tool for guaranteeing reasonable exploitation and utilization of groundwater resources. However, there is a lack of associated studies, especially compensation budget. We proposed an integrated groundwater compensation standard model, which consisted of four components: base, stimulus and punishment, research and development, and potential risk. The priority level of compensation was estimated by considering regional climate and economic conditions comprehensively. The model was applied to a total of 11 cities in Shanxi Province to calculate the groundwater ecolo-gical compensation standard. The results showed that the base compensation accounted for the largest proportion in the total compensation, with the non-market value contributing more than 60%. Our results indicated that groundwater had a high regulated service value. From 2008 to 2017, the development coefficient of each city had significantly increased, suggesting the improved regional economic level and enhanced compensation capacity. Compensation priority was affected by the non-market value of groundwater and economic level, and obvious difference in the compensation priority existed in all the cities, implying the requirement for the implement of groundwater ecological compensation. Meanwhile, we suggested that groundwater risk compensation system should be improved, special funds should be set up for supporting research projects on groundwater ecological compensation, and long-term effective compensation mechanisms should be established.

Low Distribution of TIM-3+ Cytotoxic Tumor-Infiltrating Lymphocytes Predicts Poor Outcomes in Gastrointestinal Stromal Tumors.

There are multiple tumor-infiltrating lymphocytes (TILs) and relevant immune checkpoints existing in gastrointestinal stromal tumor (GIST), which provides opportunities and rationales for developing effective immunotherapies. Recent studies have suggested that checkpoint TIM-3/Gal-9 plays a pivotal role on immune response in multiple tumors, similar to the PD-1/PD-L1, emerging as a potential therapeutic target. However, their functions in GIST are unrevealed. Hence, the expression of immune checkpoints TIM-3 and Gal-9, as well as the infiltration of CD8+ T cells and NK cells, is described in 299 cases of GIST specimens. The results showed that TIM-3 and Gal-9 are mainly expressed in TILs, rarely in tumor cells. Expression levels of TIM-3 and Gal-9 significantly differ in varying risks of GIST and exert opposite distribution trends. Indicated by prognosis analysis, high TIM-3 expression of TILs was associated with improved outcome, while low expression levels of TIM-3 in combination with low amounts of CD8+ and CD56+ TILs predict extremely poor survival. The integrated analysis of TIM-3+, CD8+, and CD56+ TILs as one biomarker is a reliable independent predictor of prognosis. In conclusion, low densities of TIM-3+ TILs are associated with poor survival, and integrated immune biomarkers lead to superior predictors of GIST prognosis.

Exon 11 homozygous mutations and intron 10/exon 11 junction deletions in the KIT gene are associated with poor prognosis of patients with gastrointestinal stromal tumors.

BACKGROUND: Gastrointestinal stromal tumors (GISTs) with different types of mutations exhibit different clinical characteristics and prognosis. This study aimed to evaluate the prognostic value of mutations in KIT and PDGFRA in a large-scale cohort of GIST patients with current therapy including surgery and imatinib. METHODS: A total of 1163 patients diagnosed with GISTs between January 2006 and December 2018 were enrolled in this study. Mutation analysis was performed for exons 9, 11, 13, and 17 of KIT and exons 12 and 18 of PDGFRA. Mutations were grouped into 12 categories according to the gene, exon, and involved codons; they were analyzed considering the clinical characteristics, disease-free survival (DFS), and overall survival (OS) of patients with GISTs. RESULTS: In low-risk GISTs, we identified two predictors of worse DFS: tumor origin in the rectum and KIT exon 11 deletion involving two or more codons. In high-risk GISTs treated with R0 resection and imatinib, patients with KIT exon 11 homozygous mutations and KIT intron 10/exon 11 junction deletions demonstrated the highest recurrence rate, indicating that these mutations can be independent prognostic factors of DFS. The presence of KIT exon 11 homozygous mutations also independently influenced OS. CONCLUSION: Low-incidence mutations such as KIT exon 11 homozygous mutations or intron 10/exon 11 junction deletions in GISTs should be carefully evaluated to explore novel treatment strategies, as tumors with these mutations have a high recurrence rate and a very poor prognosis after surgery followed by imatinib adjuvant treatment.

Clinicopathologic characteristics, diagnostic clues, and prognoses of patients with multiple sporadic gastrointestinal stromal tumors: a case series and review of the literature.

BACKGROUND: Most sporadic gastrointestinal stromal tumors (GISTs) occur as solitary tumors, while multiple sporadic GISTs are extremely rare and often misdiagnosed as metastatic GISTs, leading to inappropriate treatment. This study aimed to investigate the clinicopathological characteristics, diagnostic clues, and prognoses of multiple sporadic GISTs. METHODS: Twenty-seven patients with multiple sporadic GISTs and 11 patients with metastatic GISTs mimicking sporadic GISTs were analyzed. The clinicopathological characteristics, genetic mutation types, and prognoses were summarized. In addition, 1066 cases of primary GISTs with a single lesion diagnosed at the same hospital were included as controls. RESULTS: Compared with 1066 cases of primary GIST with a single lesion, multiple sporadic GISTs occurred at an older age, were more common in women than in men, and were located mainly in the stomach. They were generally small in size, had a low mitotic index and were more often rated as very low risk/low risk. Mutation analysis of all available lesions revealed different KIT/PDGFRA mutation patterns among tumors from the same patients. No patient relapsed during the follow-up period. Among 11 patients with metastatic GISTs that mimicked multiple sporadic GISTs, multiple lesions from the same patient always had concordant pathological and mutational characteristics; namely, they carried an identical KIT/PDGFRA mutation, and the mitotic index was usually high. CONCLUSIONS: The prognoses of patients with multiple sporadic GISTs were not worse than those of patients with a single lesion of the same risk under the same treatment. When it was difficult to distinguish multiple sporadic GISTs from metastatic GISTs, multiple lesions in the same patient carried different KIT/PDGFRA mutation patterns, which supported tumor multiplicity, while the concordant hypermitotic phase in multiple lesions of GISTs suggested that the tumor was metastatic.

The expression of lacrimal androgen-binding proteins in mice Pseudomonas aeruginosa keratitis.

AIM: To investigate the expression of lacrimal androgen-binding proteins (ABPs) in mice Pseudomonas aeruginosa (P. aeruginosa) keratitis. METHODS: P. aeruginosa mice model from different gender was developed by intra-stromal injection. The expression of lacrimal ABPs in lacrimal gland specimens from P. aeruginosa keratitis mice was detected by the quantitative polymerase chain reaction (qRT-PCR). Corneal virulence was evaluated based on clinical scores. To study the mechanism of lacrimal ABPs' expression, experimental subjects were pre-treated with 4E-BP1 inhibitor, and were used to evaluate the expression levels by qRT-PCR. RESULTS: Compared with control groups, the expression of ABPα, ABPη and ABPζ in lacrimal gland from P. aeruginosa keratitis mice had no meaningful changes, while ABPε and ABPδ were significantly higher at 1d after infection. The expression of ABPδ in lacrimal gland of male mice was higher than female mice, regardless of whether or not P. aeruginosa keratitis occurred. After 4E-BP1 inhibitor subconjunctival injection or lacrimal injection, the expression of ABPδ and ABPε has no significant change compared with the control group. CONCLUSION: ABPδ and ABPε secreted by mice lacrimal gland may involve in the progress of alleviating the severity of corneal damage in P. aeruginosa keratitis. The expression of ABPδ and ABPε upon P. aeruginosa infection is independent of cap-dependent mRNA translation activated by 4E-BP1.

Correction to: The lncRNA UCA1 promotes proliferation, migration, immune escape and inhibits apoptosis in gastric cancer by sponging anti-tumor miRNAs.

Following publication of the original article [1], authors reported Pro. Gang Zhao has to be considered as another corresponding author, according to his important contribution.

The lncRNA UCA1 promotes proliferation, migration, immune escape and inhibits apoptosis in gastric cancer by sponging anti-tumor miRNAs.

BACKGROUND: UCA1 is a long non-coding RNA which was found overexpressed in various human cancers including gastric cancer (GC). It is identified that UCA1 promotes GC cells proliferation, migration and invasion, however, the role of UCA1 during the processes of immune escape is still not unclear. METHODS: We collected 40 paired GC and non-tumor tissue samples. The level of UCA1 in GC and control tissue samples were determined by in situ hybridization and qRT-PCR. Cell viability was determined by MTT assay. GC cells' migration capacities were examined by transwell assay. To understand the roles of UCA1 during immune escape, wildtype or UCA1 KO GC cells co-cultured with peripheral blood mononuclear cells or cytokine-induced killer cells in vitro. Mouse model was used to examine the function of UCA1 in vivo. RESULTS: UCA1 promoted GC cells proliferation and migration, and inhibit apoptosis. UCA1 repressed miR-26a/b, miR-193a and miR-214 expression through direct interaction and then up-regulated the expression of PDL1. UCA1-KO GC cells could induce a higher IFNγ expression when co-cultured with peripheral blood mononuclear cells (PBMCs), and have a lower survival rate when co-cultured with cytokine-induced killer (CIK) cells in vitro. UCA1-KO GC cells formed smaller tumors, had higher miR-26a, -26b, -193a and - 214 level, reduced cell proliferation and increased apoptosis in xenograft mouse model. CONCLUSIONS: UCA1 overexpression protected PDL1 expression from the repression of miRNAs and contributed to the GC cells immune escape. UCA1 could serve as a potential novel therapeutic target for GC treatment.

Aberrant accumulation of Dickkopf 4 promotes tumor progression via forming the immune suppressive microenvironment in gastrointestinal stromal tumor.

BACKGROUND: Drug resistance and tumor recurrence are the major concerns in clinical practices of gastrointestinal stromal tumor (GIST), with the urgent requirement for exploring undiscovered pathways driving malignancy. To deal with these, recent studies have made many efforts to explore prognosis indicators and establish potential therapeutic targets. METHODS: Expression profiles of different risks of GISTs were described and abundant clinical evidences supported our findings in this study. Following exploration in vitro by cell experiments and verification in vivo using tumor microarray were taken to elucidate the underlying mechanism, which drove the malignancy in GIST. RESULTS: Dickkopf 4 (DKK4), as the canonical Wnt pathway antagonist, was unexpectedly and universally upregulated in high-risk GISTs, and aberrant accumulation of DKK4 was closely correlated with poor prognosis. In addition, tumor-derived DKK4 could decrease immune cells infiltration and activation in the tumor microenvironment, which decreased the antitumor effects in return. And this phenomenon was recurrent in human tumor specimens. CONCLUSIONS: Our findings identified DKK4 as a proper tumor biomarker for prognosis predicting and recurrence monitoring, and suggested a novel immune-escape mechanism driving malignancy in GIST, which might be a potential therapeutic target to improve the effects of canonical RTK therapy and combined immunotherapy.

Targeting mTORC2 component rictor inhibits cell proliferation and promotes apoptosis in gastric cancer.

The mammalian target of rapamycin (mTOR) kinase acts downstream of phosphoinositide 3-kinase/Akt and plays an important role in tumor growth and progression of gastric cancer. It is well characterized that mTOR complex1 (mTORC1) controls cell metabolism and proliferation, whereas the contribution of mTOR complex2 (mTORC2) and its key component, Rictor, remains poorly understood. Therefore, we investigated clinical significance of Rictor expression by immunohistochemical analysis of 391 tissue samples from gastric cancer patients. In addition, the roles of Rictor in cell proliferation, apoptosis, migration and invasion in vitro were evaluated by RNA interference. The results showed that over expression of Rictor was associated with increased tumor size, depth of tumor invasion, lymph node metastasis and advanced TNM stage, together with poorer overall and relapse-free survival. Stable sh-RNA mediated down-regulation of Rictor significantly inhibited SGC7901 and MGC803 gastric cancer cells proliferation, migration and invasion. Furthermore, Rictor knockdown attenuated cell cycle progression and enhanced apoptosis, synergistic with treatment of mTORC1 inhibitor rapamycin owing to abrogating the feedback activation of Akt. Our findings identify Rictor as an important mediator of tumor progression and metastasis, providing the rationale for targeting both mTORC1 and mTORC2 as part of therapeutic strategy for gastric cancer.

miRNA-218-loaded carboxymethyl chitosan - Tocopherol nanoparticle to suppress the proliferation of gastrointestinal stromal tumor growth.

Gastrointestinal stromal tumors (GIST) are one of the most common forms of mesenchymal cancers of the gastrointestinal tract. Although chemotherapeutic drugs inhibited the proliferation of GIST, however, sizable proportion of people developed resistance and therefore difficult to treat. In the present study, O-carboxymethyl chitosan (OCMC)-tocopherol polymer conjugate was synthesized and formulated into stable polymeric nanoparticles. The main aim of present study was to increase the therapeutic efficacy of miR-218 in GIST. The mean size of nanoparticles was ~110nm with a spherical shape. The miR-218 NP has been shown inhibit the cell proliferation and exhibited a superior cell apoptosis. The miR-218 NP inhibited the cell invasion and promoted the apoptosis of GIST cancer cells. In the present study, we have successfully showed that KIT1 is the target gene of miR-218 as shown by the luciferase reporter assay. These findings collectively suggest the miR-218 loaded nanoparticle by virtue of effective transfection could act as a tumor suppressor miRNA in the treatment of GIST.

Long non-coding RNA LINC00628 functions as a gastric cancer suppressor via long-range modulating the expression of cell cycle related genes.

To discover new biomarkers for gastric cancer (GC) diagnose and treatment, we screened the lncRNAs in GC tissues from 5 patients. We found 6 lncRNAs had altered expression, and in the same time, the levels of their neighboring genes (located near 300 kb upstream or downstream of lncRNA locus) were significantly changed. After confirming the results of microarray by qRT-PCR in 82 GC patients, the biological function of LINC00628 was examined through cell proliferation and apoptosis, cell migration and invasion, colony formation assay and cell cycle detection. We confirmed that LINC00628 functions as a GC suppressor through suppressing proliferation, migration and colony formation of cancer cells. Furthermore, LINC00628 can also suppress the tumor size in mouse xenograft models. Although LINC00628 can modulate LRRN2 expression, the GC suppressor function of LINC00628 is not LRRN2 dependent. The result of mRNA microarray indicated that LINC00628 perform GC inhibitor function through long-range modulating cell cycle related genes. Importantly, we confirmed that LINC00628 mainly located in the nucleus and interacted with EZH2, and modulated genes expression by regulating H3K27me3 level. This research shed light on the role of dysregulated LINC00628 during GC process and may serve as a potential target for therapeutic intervention.

Correlations of fascin-1 and cadherin-17 protein expression with clinicopathologic features and prognosis of patients with gastric cancer.

We aim to explore the associations of fascin-1 and cadherin-17 in gastric cancer (GC) to the clinicopathologic features and prognosis of GC. Case group included 204 GC tissues while control group comprised 204 paired adjacent cancer tissues. Expressions of fascin-1 and cadherin-17 were measured with immunohistochemistry and western blot and then analyzed statistically in relation to clinicopathologic features and survival time. Survival curve was drawn by Kaplan-Meier method, and independent prognostic factors were identified with Cox proportional hazards regression model. Fascin-1 was positively expressed in 45.1 % of GC tissues and in 27.5 % of adjacent cancer tissues, respectively (P < 0.05); cadherin-17 was positively expressed in 51.5 % of GC tissues and in 33.8 % of adjacent cancer tissues (P < 0.05). Fascin-1 expression in GC tissues was related to tumor size (P = 0.001) and Lauren classification (P = 0.001). Cadherin-17 expression in GC tissues was related to tumor size (P < 0.001), Lauren classification (P = 0.009), clinical staging (P = 0.001), and distant metastasis (P = 0.002). Fascin-1 expression was positively correlated with cadherin-17 expression in GC tissues (r = 0.828, P < 0.01). Patients with positive expression of both fascin-1 and cadherin-17 had lower survival rates than those with negative expression (all P < 0.01). Cox regression analysis showed that fascin-1 expression, cadherin-17 expression, tumor size, and differentiation were independent risk factors for GC (all P < 0.05). Fascin-1 and cadherin-17 are related to clinicopathologic features of GC and are independent adverse prognostic factors for GC.

SLITRK3 expression correlation to gastrointestinal stromal tumor risk rating and prognosis.

AIM: To assess the influence of SLIT and NTRK-like family member 3 (SLITRK3) on the prognosis of gastrointestinal stromal tumor (GIST) and determine whether SLITRK3 can help improve current risk stratification systems. METHODS: We hypothesized that SLITRK3 could be used as a prognostic molecular biomarker for GIST. 35 fresh tumor samples and 417 paraffin-embedded specimens from GIST patients were utilized. SLITRK3 mRNA expression in GIST tumor tissue was detected by real-time polymerase chain reaction, and SLITRK3 protein levels were estimated by immunohistochemistry. The correlation of SLITRK3 expression with various tumor clinicopathological characteristics and follow-up data were analyzed. RESULTS: GIST tumors had high expression of SLITRK3 compared with adjacent normal tissues and the expression level gradually increased with risk grade. SLITRK3 protein expression was closely associated with gastrointestinal bleeding, tumor site, tumor size, mitotic index, and National Institutes of Health (NIH) classification. Survival analysis showed that SLITRK3 expression was closely correlated with overall survival and disease-free survival of GIST patients. Multivariate analysis also identified SLITRK3 expression, mitotic index, and NIH stage as significant risk factors of GIST recurrence. CONCLUSION: SLITRK3 expression is a highly significant predictor of GIST recurrence and metastasis. Combinations of SLITRK3 and NIH stage have strong predictive and prognostic value, and are feasible markers for clinical practice in gastrointestinal stromal tumor.

TEM7 (PLXDC1), a key prognostic predictor for resectable gastric cancer, promotes cancer cell migration and invasion.

Tumor endothelial marker 7 (TEM7) is a new candidate of molecular target for antiangiogenic therapy. This study aims to evaluate its expression in gastric cancer (GC) and to explore the correlation between its expression and the clinical outcome of patients. Expression of TEM7 was analyzed in both tumor tissues and cell lines of GC by real-time quantitative RT-PCR (qRT-PCR) and Western blot. RNA interference (RNAi) approaches were used to investigate the biological functions of TEM7. The effects of TEM7 on cell migration and invasion were evaluated by Transwell assays. In vitro experiments revealed that TEM7 was significantly overexpressed in GC cell lines (N87, AGS and SGC-7901) by 2-fold to 4-fold, and knockdown of TEM7 could significantly inhibit cancer cell migration and invasion. For GC patients, TEM7 gene expression was elevated in tumors in most cases (25/31), and its expression was closely correlated with tumor differentiation, depth of cancer invasion, lymphatic metastasis and TNM stage. The overall survival of TEM7 (-) group was significantly higher than that of TEM7 (+) group (P = 0.048) and TEM7 (++) group (P = 0.003). TEM7 is highly expressed in GC and is likely correlated with tumor invasion and migration, and thus its expression is closely related to the clinical outcome of patients.

Preoperative imatinib treatment in patients with advanced gastrointestinal stromal tumors: patient experiences and systematic review of 563 patients.

Preoperative IM therapy for GIST is now a research focus. Due to the low incidence of the disease, there are few RCTs on the preoperative treatment for advanced GIST, let alone relevant meta-analysis. Efficacy of this therapy and targeting population are still undetermined. Therefore, the first part of this article is composed of a controlled retrospective study and demonstrates that preoperative therapy with IM can significantly improve the outcome of advanced GIST. In the second part of the paper, we further investigated what portion of advanced GIST patients benefit more from the therapy, based on a meta-analysis. As the disease is relatively rare, we involved 563 cases in the meta-analysis, much higher than in the controlled clinical studies (51 cases). The objective of this paper is to investigate effects of surgical resection on imatinib-treated advanced GIST. Twenty-two consecutive advanced GIST patients (Group A) with preoperative IM treatment were compared to 29 patients (Group B) who underwent initial tumor resection during the same period. Subsequently, a systematic review of 563 patients was applied to identify the benefit of the advanced GIST patients receiving imatinib before surgery. Compared with Group B, less patients in Group A underwent multivisceral resection (18.2% versus 48.3%, P = 0.026) or suffered tumor rupture at time of surgery (0% versus 17.2%, P = 0.04). The 3-year estimated progression-free survival of Group A (94.4%) was also superior to that of Group B (61.4%; P = 0.045). Subsequent meta-analysis indicated that primarily unresectable patients had higher complete resection and 2-year PFS rates than recurrent/metastasis patients (P = 0.005 and 0.20, respectively); (b) stable disease (SD) patients had better outcome in resection including resectability rate (P < 0.0001), PFS (P < 0.00001) and OS (P = 0.0008) than progressive disease (PD) patients; (c) in recurrent/metastatic PD patients, surgery played a minor role, because they had a higher bulky residual disease rate (P = 0.0005) and higher progression risk (P < 0.00001) within 2 years after surgery. Preoperative IM treatment improves prognosis of advanced GISTs. Among recurrent/metastatic patients, postimatinib surgery may benefit those who have SD after IM treatment but not those resistant to IM.

Lysyl oxidase-like 4 (LOXL4) promotes proliferation and metastasis of gastric cancer via FAK/Src pathway.

BACKGROUND: Lysyl oxidase-like 4 (LOXL4) has been found up-regulated in a variety of human malignancies, but its clinical significance and functional roles in gastric cancer (GC) remain unknown. METHODS: Lysyl oxidase-like 4 (LOXL4) expression level in tumor tissues and human GC cell lines was evaluated by quantitative real-time polymerase chain reaction, Western blotting and immunohistochemical analyses. Its clinical significance was inferred from the analysis of 379 tissue samples of patients with GC using tissue microarray. The roles of LOXL4 in cell proliferation, migration and invasion in vitro were analyzed by gene over-expression, RNA interference and recombinant protein. Effects of LOXL4 on regulation of focal adhesion kinase/Src kinase (FAK/Src) pathway were examined by Western blotting. RESULTS: Lysyl oxidase-like 4 (LOXL4) was up-regulated in GC tissues relative to paired non-tumor tissues, and this over-expression was significantly associated with tumor size, depth of tumor invasion, lymph node metastasis, tumor-node-metastasis (TNM) stages and poorer overall survival. Over-expression of LOXL4 has promotive effects on GC cell proliferation, migration and invasion in vitro, consistent with this, LOXL4 knockdown has inhibitive effects on GC cell proliferation, migration and invasion. Furthermore, recombinant human LOXL4 protein also promoted GC cell proliferation and migration. Subsequent mechanistic studies showed that LOXL4 could activate FAK/Src pathway to enhance cell-extracellular matrix adhesion. CONCLUSIONS: Taken together, our data reveal that up-regulation of LOXL4 expression is a frequent event in GC progression, contributes to tumor cell proliferation and metastasis, and LOXL4 may be a potential independent prognostic marker and therapeutic target for GC.