Adipose-derived mesenchymal stem cells induced PAX8 promotes ovarian cancer cell growth by stabilizing TAZ protein

Our previous studies have shown that the Adipose-derived mesenchymal stem cells (ADSCs) can regulate metastasis and development of ovarian cancer. However, its specific mechanism has yet to be fully revealed. In this study, an RNA-seq approach was adopted to compare the differences in mRNA levels in ovarian cancer cells being given or not given ADSCs. The mRNA level of paired box 8 (PAX8) changed significantly and was confirmed as an important factor in tumour-inducing effect of ADSCs. In comparison with the ovarian cancer cells cultured in the common growth medium, those cultured in the medium supplemented with ADSCs showed a significant increase of the PAX8 level. Moreover, the cancer cell growth could be restricted, even in the ADSC-treated group (P < .05), by inhibiting PAX8. In addition, an overexpression of PAX8 could elevate the proliferation of ovarian cancer cells. Moreover, Co-IP assays in ovarian cancer cells revealed that an interaction existed between endogenous PAX8 and TAZ. And the PAX8 levels regulated the degradation of TAZ. The bioluminescence images captured in vivo manifested that the proliferation and the PAX8 expression level in ovarian cancers increased in the ADMSC-treated group, and the effect of ADSCs in promoting tumours was weakened through inhibiting PAX8. Our findings indicate that the PAX8 expression increment could contribute a role in promoting the ADSC-induced ovarian cancer cell proliferation through TAZ stability regulation.     

卵巢癌组织中UHRF1蛋白的表达及其与卵巢癌细胞增殖和侵袭的关系

目的:研究卵巢癌组织中泛素样含PHD和环指域1(Ubiquitin-like with PHD and ring finger domains 1,UHRF1)蛋白的表达及UHRF1对卵巢癌细胞增殖、侵袭的影响。方法:选取卵巢癌组织和癌旁正常组织,采用蛋白印迹法(Western blot)检测其UHRF1的蛋白表达。体外培养卵巢癌SKOV-3细胞株,分别转染UHRF1的si RNA和阴性对照si RNA,采用CCK-8检测细胞活力,Transwell检测细胞侵袭能力,荧光定量聚合酶链式反应法(FQ-PCR)检测Cyclin D1、CDK6、MMP2和MMP9的m RNA表达。结果:卵巢癌组织中UHRF1蛋白表达水平显著高于癌旁正常组织(P0.05);与转染阴性对照si RNA的SKOV-3细胞相比,转染UHRF1的si RNA的SKOV-3细胞活力明显降低、侵袭细胞数目明显减少(P0.05),且细胞中Cyclin D1、CDK6、MMP2和MMP9基因的m RNA表达水平显著降低(P0.05)。结论:UHRF1蛋白在卵巢癌组织中呈高表达状态,且可促进卵巢癌细胞的增殖和侵袭。     

Role of GPER on proliferation,migration and invasion in ligand‐independent manner in human ovarian cancer cell line SKOV3

G protein‐coupled estrogen receptor (GPER) is identified as a critical estrogen receptor, in addition to the classical estrogen receptors ERα and ERβ. In ERα‐negative ovarian cancer cells, our previous studies have found that estrogen stimulated cell proliferation and metastasis via GPER. However, the ligand‐independent function of GPER in ovarian cancer cells is still not clear. Herein, we describe that GPER has a co‐expression with ERα and ERβ, which are first determined in SKOV3 ovarian cancer cell line. In the absence of estrogen, GPER depletion by specific siRNA inhibits the proliferation, migration and invasion of SKOV3 cells. Whereas abrogation of ERα or ERβ by specific antagonist MPP and PHTPP has the opposite effects for stimulation of cell growth. Markedly, GPER knockdown attenuates MPP or PHTPP‐induced cell proliferation, migration and invasion. Furthermore, GPER modulates protein expression of the cell cycle critical components, c‐fos and cyclin D1 and factors for cancer cell invasion and metastasis, matrix metalloproteinase 2 (MMP‐2) and MMP‐9. These findings establish that GPER ligand‐independently stimulates the proliferation, migration and invasion of SKOV3 cells. Knockdown of GPER attenuates the progression of ovarian cancer that caused by functional loss of ERα or ERβ. Targeting GPER provides new aspect as a potential therapeutic strategy in ovarian cancer. Copyright © 2015 John Wiley & Sons, Ltd.     

Daphnetin triggers ROS-induced cell death and induces cytoprotective autophagy by modulating the AMPK/Akt/mTOR pathway in ovarian cancer

BackgroundOvarian cancer is one of the most common gynecological malignancies in the world. Daphnetin (Daph) was previously reported to possess antitumor potential, but its potential and molecular mechanisms in ovarian cancer remain poorly understood.PurposeIn the current study, we aimed to explore the antitumor effect and detailed mechanisms of Daph in ovarian cancer cells.MethodsThe cytotoxic effect of Daph on ovarian cells was determined in vitro and in vivo. Cell growth, proliferation, apoptosis and ROS generation were measured by CCK8 assays, colony formation assays and flow cytometry. Western blotting was used to evaluate the related signal proteins. Immunofluorescence and transmission electron microscopy were used to evaluate markers of autophagy and autophagic flux. The antitumor effects were observed in the A2780 xenograft model. Moreover, Daph-induced autophagy was observed by enhanced LC3-II accumulation and endogenous LC3 puncta, and an autophagy inhibitor further enhanced the antitumor efficacy of Daph, which indicated that the cytoprotective role of autophagy in ovarian cancer.ResultsWe found that Daph exhibited antitumor effects by inducing ROS-dependent apoptosis in ovarian cancer, which could be reversed by N-acetyl cysteine (NAC). The AMPK/Akt/mTOR pathway was involved in Daph-mediated cytoprotective autophagy, and when Daph-mediated the expression level of AMPK and autophagy were blocked, there was robust inhibition of cell proliferation and induction of apoptosis. In addition, in the A2780 xenograft model, combined treatment with Daph and an autophagy inhibitor showed obvious synergetic effects on the inhibition of cell viability and promotion of apoptosis, without any side effects.ConclusionOur results suggest that Daph triggers ROS-induced cell apoptosis and induces cytoprotective autophagy by modulating the AMPK/Akt/mTOR pathway. Moreover, the combination of Daph and autophagy inhibitor may be a potential therapeutic strategy for ovarian cancer.     

Convallatoxin promotes apoptosis and inhibits proliferation and angiogenesis through crosstalk between JAK2/STAT3 (T705) and mTOR/STAT3 (S727) signaling pathways in colorectal cancer

BackgroundAberrant activation of STAT3 is frequently encountered and promotes survival, cellular proliferation, migration, invasion and angiogenesis in tumor cell. Convallatoxin, triterpenoid ingredient, exhibits anticancer pharmacological properties.PurposeIn this work, we investigated the anticancer potential of convallatoxin and explored whether convallatoxin mediates its effect through interference with the STAT3 activation in colorectal cancer cells.MethodsIn vitro, the underlying mechanisms of convallatoxin at inhibiting STAT3 activation were investigated by homology modeling and molecular docking, luciferase reporter assay, MTT assay, RT-PCR, Western blotting and immunofluorescence assays. Changes in cellular proliferation, apoptosis, migration, invasion and angiogenesis were analyzed by EdU labeling assay, colony formation assay, flow cytometry assay, wound-healing assay, matrigel transwell invasion assay and tube formation assays. And in vivo, antitumor activity of convallatoxin was assessed in a murine xenograft model of HCT116 cells.ResultsConvallatoxin decreased the viability of colorectal cancer lines. Moreover, convallatoxin reduced the P-STAT3 (T705) via the JAK1, JAK2, and Src pathways and inhibited serine-727 phosphorylation of STAT3 via the PI3K-AKT-mTOR-STAT3 pathways in colorectal cancer cells. Interestingly, we discovered the crosstalk between mTOR and JAK2 in mTOR/STAT3 and JAK/STAT3 pathways, which collaboratively regulated STAT3 activation and convallatoxin play a role in it. Convallatoxin also downregulated the expression of target genes involved cell survival (e.g., Survivin, Bcl-xl, Bcl-2), proliferation (e.g., Cyclin D1), metastasis (e.g., MMP-9), and angiogenesis (e.g., VEGF). Indeed, we found that convallatoxin inhibited tube formation, migration, and invasion of endothelial cells, and inhibited the proliferation. Finally, in vivo observations were confirmed by showing antitumor activity of convallatoxin in a murine xenograft model.ConclusionThe result of the current study show that convallatoxin promotes apoptosis and inhibits proliferation and angiogenesis through crosstalk between JAK2/STAT3 (T705) and mTOR/STAT3 (S727) signaling pathways in colorectal cancer cells and indicate that convallatoxin could be a valuable candidate for the development of colorectal cancer therapeutic.     

Aiduqing formula suppresses breast cancer metastasis via inhibiting CXCL1-mediated autophagy

BackgroundMetastasis is the most common lethal cause of breast cancer-related death. Recent studies have implied that autophagy is closely implicated in cancer metastasis. Therefore, it is of great significance to explore autophagy-related molecular targets involved in breast cancer metastasis and to develop therapeutic drugs.PurposeThis study was designed to investigate the anti-metastatic effects and autophagy regulatory mechanisms of Aiduqing (ADQ) formula on breast cancer.Study Design/MethodsMultiple cellular and molecular experiments were conducted to investigate the inhibitory effects of ADQ formula on autophagy and metastasis of breast cancer cells in vitro. Meanwhile, autophagic activator/inhibitor as well as CXCL1 overexpression or interference plasmids were used to investigate the underlying mechanisms of ADQ formula in modulating autophagy-mediated metastasis. Furthermore, the zebrafish xenotransplantation model and mouse xenografts were applied to validate the inhibitory effect of ADQ formula on autophagy-mediated metastasis in breast cancer in vivo.ResultsADQ formula significantly inhibited the proliferation, migration, invasion and autophagy but induced apoptosis of high-metastatic breast cancer cells in vitro. Similar results were also observed in starvation-induced breast cancer cells which exhibited elevated metastatic ability and autophagy activity. Mechanism investigations further approved that either CXCL1 overexpression or autophagic activator rapamycin can significantly abrogated the anti-metastatic effects of ADQ formula, suggesting that CXCL1-mediated autophagy may be the crucial pathway of ADQ formula in suppressing breast cancer metastasis. More importantly, ADQ formula suppressed breast cancer growth, autophagy, and metastasis in both the zebrafish xenotransplantation model and the mouse xenografts.ConclusionOur study not only revealed the novel function of CXCL1 in mediating autophagy-mediated metastasis but also suggested ADQ formula as a candidate drug for the treatment of metastatic breast cancer.     

The novel estrogen receptor GPER regulates the migration and invasion of ovarian cancer cells

G protein-coupled estrogen receptor (GPER) was identified as a new member of the estrogen receptor family in recent years. It has become apparent that GPER mediates the non-genomic signaling of 17β-estradiol (E₂) in a variety of estrogen-related cancers. Our previous study has found that GPER was overexpressed in human epithelial ovarian cancer and was positively correlated with the expression of matrix metalloproteinase 9 (MMP-9), which suggested GPER might promote the metastasis of ovarian cancer. However, the mechanisms underlying GPER-dependent metastasis of ovarian cancer are still not clear. In the present study, estrogen receptor α (ERα)-negative/GPER-positive OVCAR5 ovarian cancer cell line was used to investigate the role of GPER in the migration and invasion of ovarian cancer. Wound healing assay and transwell matrigel invasion assay were performed to determine the potentials of cell migration and invasion, respectively. The production and activity of MMP-9 in OVCAR5 cells were examined by Western blot and gelatin zymography analysis. The results showed that E₂ and selective GPER agonist G-1 increased cell motility and invasiveness, and upregulated the production and proteolytic activity of MMP-9 in OVCAR5 cells. Small interfering RNA (siRNA) targeting GPER and G protein inhibitor pertussin toxin (PTX) inhibited the migration and invasion of OVCAR5 cells, and also reduced the expression and activity of MMP-9. Our data suggested that GPER promoted the migration and invasion of ovarian cancer cells by increasing the expression and activity of MMP-9. GPER might play an important role in the progression of ovarian cancer.     

Induction of autophagy enhances apoptotic cell death via epidermal growth factor receptor inhibition by canertinib in cervical cancer cells

BackgroundIt has been known epidermal growth factor receptor (EGFR) frequently overexpressed in cervical cancer. High levels of EGFR expression in their tumors leads to a poor prognosis and inhibition frequently induces autophagy in cancer cells. This study aimed to investigate whether EGFR inhibition by canertinib induces autophagy and this induction influence the effect of Palladium (Pd) (II) complex and 5-fluorouracil (5-FU) especially in nontoxic doses.MethodsCytotoxicity was evaluated by using SRB assay. Apoptosis, autophagy, and EGFR key markers were determined by flow cytometry, fluorescence staining, and immunoblotting. Colony formation, invasion, and wound healing assays were performed to investigate cell proliferation, invasion, and migration, respectively.ResultsBlocking EGFR by the pan-ErbB tyrosine kinase inhibitor canertinib inhibited cell growth of HeLa cervical cancer cells in combination with Pd(II) complex and 5-FU. Combination of canertinib and Pd(II) complex promotes autophagy and apoptosis of HeLa cancer cells via blockade of the PI3K/AKT and MAPK/ERK pathway, which leads to cervical cancer cell death. ROS accumulation and DNA damage were increased after combinatorial treatment which causes depolarization of the mitochondrial inner membrane and leads to apoptotic cell death. Canertinib combined with Pd(II) complex leads to inhibition of migration and invasion.ConclusionInhibition of EGFR signaling by canertinib in combination with Pd(II) complex promotes apoptosis and autophagy via blockade of the PI3K/AKT and MAPK/ERK.General significanceThe cytotoxic activity of Pd(II) complex and 5-FU on HeLa cells is mediated by EGFR inhibition and autophagy induction, leading to activation of mitochondrial apoptotic cell death.     

Human Omental-Derived Adipose Stem Cells Increase Ovarian Cancer Proliferation,Migration, and Chemoresistance

Objectives

Adipose tissue contains a population of multipotent adipose stem cells (ASCs) that form tumor stroma and can promote tumor progression. Given the high rate of ovarian cancer metastasis to the omental adipose, we hypothesized that omental-derived ASC may contribute to ovarian cancer growth and dissemination.

Materials and Methods

We isolated ASCs from the omentum of three patients with ovarian cancer, with (O-ASC4, O-ASC5) and without (O-ASC1) omental metastasis. BM-MSCs, SQ-ASCs, O-ASCs were characterized with gene expression arrays and metabolic analysis. Stromal cells effects on ovarian cancer cells proliferation, chemoresistance and radiation resistance was evaluated using co-culture assays with luciferase-labeled human ovarian cancer cell lines. Transwell migration assays were performed with conditioned media from O-ASCs and control cell lines. SKOV3 cells were intraperitionally injected with or without O-ASC1 to track in-vivo engraftment.

Results

O-ASCs significantly promoted in vitro proliferation, migration chemotherapy and radiation response of ovarian cancer cell lines. O-ASC4 had more marked effects on migration and chemotherapy response on OVCA 429 and OVCA 433 cells than O-ASC1. Analysis of microarray data revealed that O-ASC4 and O-ASC5 have similar gene expression profiles, in contrast to O-ASC1, which was more similar to BM-MSCs and subcutaneous ASCs in hierarchical clustering. Human O-ASCs were detected in the stroma of human ovarian cancer murine xenografts but not uninvolved ovaries.

Conclusions

ASCs derived from the human omentum can promote ovarian cancer proliferation, migration, chemoresistance and radiation resistance in-vitro. Furthermore, clinical O-ASCs isolates demonstrate heterogenous effects on ovarian cancer in-vitro.     

Retracted: In vivo and in vitro effects of microRNA-221 on hepatocellular carcinoma development and progression through the JAK–STAT3 signaling pathway by targeting SOCS3

Hepatocellular carcinoma (HCC), as the third leading cancer-caused deaths, prevails with high mortality, and affects more than half a million individuals per year worldwide. A former study revealed that microRNA-221 (miR-221) was involved in cell proliferation of liver cancer and HCC development. The current study aims to evaluate whether miR-221 targeting SOCS3 affects HCC through JAK–STAT3 signaling pathway. A series of miR-221 mimic, miR-221 inhibitor, siRNA against SOCS3, and SOCS3 plasmids were introduced to SMMC7721 cells with the highest miR-221 expression assessed. The expression of JAK–STAT3 signaling pathway–related genes and proteins was determined by Western blot analysis. Cell apoptosis, viability, migration, and invasion were evaluated by means of flow cytometry, 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide, and transwell assays, respectively. HCC xenograft in nude mice was performed to measure HCC tumor growth. miR-221 was found to be highly expressed but SOCS3 was poorly expressed in HCC tissues. miR-221 expression was correlated with lymph node metastasis (LNM) and tumor node metastasis (TNM) of HCC, and SOCS3 expression was correlated with LNM, differentiation and TNM of HCC. SOCS3 is a target gene of miR-221. MiR-221 mimic or si-SOCS3 exposure was found to induce cell viability, migration, and invasion, and reduce apoptosis. MiR-221 inhibitor was observed to have inhibitory effects on HCC cell proliferation, migration, and invasion. Moreover, the expression of JAK–STAT3 signaling pathway was suppressed by miR-221 inhibitor. Downregulated miR-221 expression could promote its target gene SOCS3 to inhibit the proliferation, invasion and migration of HCC cells by repressing JAK–STAT3 signaling pathway.     

Timing is critical for an effective anti-metastatic immunotherapy: the decisive role of IFNγ/STAT1-mediated activation of autophagy

Background

Immunotherapy is often recommended as an adjuvant treatment to reduce the chance of cancer recurrence or metastasis. Interestingly, timing is very important for a successful immunotherapy against metastasis, although the precise mechanism is still unknown.

Methods and Findings

Using a mouse model of melanoma metastasis induced by intravenous injection of B16-F10 cells, we investigated the mechanism responsible for the diverse efficacy of the prophylactic or therapeutic TLR4 and TLR9 agonist complex against metastasis. We found that the activation of TLR4 and TLR9 prevented, but did not reverse, metastasis because the potency of this combination was neither sufficient to overcome the tumor cell-educated immune tolerance nor to induce efficacious autophagy in tumor cells. The prophylactic application of the complex promoted antimetastatic immunity, leading to the autophagy-associated death of melanoma cells via IFNγ/STAT1 activation and attenuated tumor metastasis. IFNγ neutralization reversed the prophylactic benefit induced by the complex by suppressing STAT1 activation and attenuating autophagy in mice. However, the therapeutic application of the complex did not suppress metastasis because the complex could not reverse tumor cell-induced STAT3 activation and neither activate IFNγ/STAT1 signaling and autophagy. Suppressing STAT3 activation with the JAK/STAT antagonist AG490 restored the antimetastatic effect of the TLR4/9 agonist complex. Activation of autophagy after tumor inoculation by using rapamycin, with or without the TLR4/9 agonist complex, could suppress metastasis.

Conclusion and Significance

Our studies suggest that activation of IFNγ/STAT1 signaling and induction of autophagy are critical for an efficacious anti-metastatic immunotherapy and that autophagy activators may overcome the timing barrier for immunotherapy against metastasis.     

The inhibitory effects of capillarisin on cell proliferation and invasion of prostate carcinoma cells

Objectives

Capillarisin (Cap), an active component of Artemisia capillaris root extracts, is characterized by its anti‐inflammatory, anti‐oxidant and anti‐cancer properties. Nevertheless, the functions of Cap in prostate cancer have not been fully explored. We evaluated the potential actions of Cap on the cell proliferation, migration and invasion of prostate carcinoma cells.

Materials and methods

Cell proliferation and cell cycle distribution were measured by water‐soluble tetrazolium‐1 and flow cytometry assays. The expression of cyclins, p21, p27, survivin, matrix metallopeptidase (MMP2 and MMP9) were assessed by immunoblotting assays. Effects of Cap on invasion and migration were determined by wound closure and matrigel transmigration assays. The constitutive and interlukin‐6 (IL‐6)‐inducible STAT3 activation of prostate carcinoma cells were determined by immunoblotting and reporter assays.

Results

Capillarisin inhibited androgen‐independent DU145 and androgen‐dependent LNCaP cell growth through the induction of cell cycle arrest at the G0/G1 phase by upregulating p21 and p27 while downregulating expression of cyclin D1, cyclin A and cyclin B. Cap decreased protein expression of survivin, MMP‐2, and MMP‐9 and therefore blocked the migration and invasion of DU145 cells. Cap suppressed constitutive and IL‐6‐inducible STAT3 activation in DU145 and LNCaP cells.

Conclusions

Our data indicate that Cap blocked cell growth by modulation of p21, p27 and cyclins. The inhibitory effects of Cap on survivin, MMP‐2, MMP‐9 and STAT3 activation may account for the suppression of invasion in prostate carcinoma cells. Our data suggest that Cap might be a therapeutic agent in treating advanced prostate cancer with constitutive STAT3 or IL‐6‐inducible STAT3 activation.

     

AKT2 contributes to increase ovarian cancer cell migration and invasion through the AKT2-PKM2-STAT3/NF-κB axis

Multiple studies have shown that protein kinase Bβ (AKT2) is involved in the development and progression of ovarian cancer, however, its precise role remains unclear. Here we explored the underlying molecular mechanisms how AKT2 promotes ovarian cancer progression. We examined the effects of AKT2 in vitro in two ovarian cancer cell lines (SKOV3 and HEY), and in vivo by metastasis assay in nude mice. The migration and invasion ability of SKOV3 and HEY cells was determined by transwell assay. Overexpression and knockdown (with shRNA) experiments were carried out to unravel the underlying signaling mechanisms induced by AKT2. Overexpression of AKT2 led to increased expression of pyruvate kinase (PKM2) in ovarian cancer cells and in lung metastatic foci from nude mice. Elevated AKT2/PKM2 expression induced cell migration and invasion in vitro, as well as lung metastasis in vivo; silencing AKT2 blocked these effects. Meanwhile, PKM2 overexpression was unable to increase AKT2 expression. The expressions of p-PI3K, p-AKT2, and PKM2 were increased when stimulated by epidermal growth factor (EGF); however, these expressions were blocked when inhibited the PI3K by LY294002. STAT3 expression was elevated and NF-κB p65 nuclear translocation was activated both in vitro and in vivo when either AKT2 or PKM2 was overexpressed; and these effects were inhibited when silencing AKT2 expression. Taken together, AKT2 increases the migration and invasion of ovarian cancer cells in vitro and promotes lung metastasis in nude mice in vivo through PKM2-mediated elevation of STAT3 expression and NF-κB activation. In conclusion, we highlight a novel mechanism of the AKT2-PKM2-STAT3/NF-κB axis in the regulation of ovarian cancer progression, and our work suggested that both AKT2 and PKM2 may be potential targets for the treatment of ovarian cancer.     

Notch1 regulates tongue cancer cells proliferation,apoptosis and invasion

Objectives: Notch1 regulates tumor biology in a complex, context-dependent manner. The roles of Notch1 in tongue cancer are still controversial. The aim of this study is to investigate the roles of Notch1 in tongue cancer.

Materials and Methods: The expression of Notch1 was tested between tongue cancer and normal samples by using immunohistochemistry. Tongue cancer cells were transfected with siRNA or plasmid, respectively. Cell proliferation, apoptosis, migration and invasion ability were tested in appropriate ways. The subcutaneous tumor model was established to observe the tumor growth.

Results: Notch1 was upregulated in tongue carcinoma tissues and the expression of Notch1 was related with tumor stage and differentiation. Overexpression of Notch1 could increase tongue cancer cells proliferation, invasion and migration. But inhibited the expression of Notch1 could decrease cells proliferation, invasion and migration and promote cell apoptosis in vitro and in vivo.

Conclusion: Our results prove that the oncogenic role of Notch1 in tongue cancer and provide the direction of targeted therapy of tongue cancer.     

Circular RNA UBE2Q2 promotes malignant progression of gastric cancer by regulating signal transducer and activator of transcription 3-mediated autophagy and glycolysis

Gastric cancer remains the third leading cause of cancer-related mortality worldwide. Emerging evidence has shown that circular RNAs (circRNAs) play a critical regulatory role in the occurrence and development of various cancers through sponging miRNAs or acting as RNA-binding protein (RBP) sponges. We found that circUBE2Q2 was significantly upregulated in GC tissues and cell lines. Knockdown of circUBE2Q2 inhibited proliferation, migration, invasion, and glycolysis, and increased autophagy in vitro. In addition, knockdown of circUBE2Q2 inhibited GC tumorigenicity and metastasis potential in vivo. A series of experiments were performed to confirm that circUBE2Q2 regulates GC progression via the circUBE2Q2-miR-370-3p-STAT3 axis and promotes tumor metastasis through exosomal communication. Further in vivo experiments confirmed that, combination treatment of circUBE2Q2 knocking down and STAT3 inhibitor has synergistic effects on the gastric cancer growth inhibition, which provides a possibility to enhance the sensitivity of targeted drugs to gastric cancer through targeting circUBE2Q2. Our findings revealed that circUBE2Q2 may serve as a new proliferation-promoting factor and prognostic marker in gastric cancer.Subject terms: Gastric cancer, Gastric cancer