Hongliang Yao

MicroRNA-124 regulates the proliferation of colorectal cancer cells by targeting iASPP.

MicroRNAs are a class of small, noncoding RNAs that function as critical regulators of gene expression by targeting mRNAs for translational repression or degradation. In this study, we demonstrate that expression of microRNA-124 (miR-124) is significantly downregulated in colorectal cancer tissues and cell lines, compared to the matched adjacent tissues. We identified and confirmed inhibitor of apoptosis-stimulating protein of p53 (iASPP) as a novel, direct target of miR-124 using target prediction algorithms and luciferase reporter gene assays. Overexpression of miR-124 suppressed iASPP protein expression, upregulated expression of the downstream signaling molecule nuclear factor-kappa B (NF-κB), and attenuated cell viability, proliferation, and colony formation in SW480 and HT-29 colorectal cancer cells in vitro. Forced overexpression of iASPP partly rescued the inhibitory effect of miR-124 on SW480 and HT29 cell proliferation. Taken together, these findings shed light on the role and mechanism of action of miR-124, indicate that the miR-124/iASPP axis can regulate the proliferation of colorectal cancer cells, and suggest that miR-124 may serve as a potential therapeutic target for colorectal cancer.

Regulatory roles of microRNA‑708 and microRNA‑31 in proliferation, apoptosis and invasion of colorectal cancer cells

MicroRNAs (miRs) function as key regulators of gene expression and their deregulation is associated with the carcinogenesis of various cancers. In the present study, the aim was to validate the potential roles and regulatory mechanisms of miR-708 and miR-31 in colorectal cancer (CRC) cells. miR-708 and miR-31 were found to be highly expressed in five CRC tissue samples. Functional studies showed that the inhibition of miR-708 and miR-31 inhibited cell proliferation and invasion, however, promoted apoptosis in vitro. Subsequently, it was identified that miR-708 and miR-31 directly target cyclin-dependent kinase inhibitor 2B (CDKN2B) by binding to the 3′ untranslated region, which suppresses the CDKN2B protein levels. In addition, the CDKN2B protein levels were significantly reduced when there was high miR-708 and miR-31 expression in the CRC tissue samples. The results indicate that miR-31 and miR-708 function in an oncogenic manner in CRC development, and inhibition of the two miRs may be used as a therapeutic strategy for patients with CRC.

Clinical efficacy of second-generation tyrosine kinase inhibitors in imatinib-resistant gastrointestinal stromal tumors: a meta-analysis of recent clinical trials

Background Primary and secondary resistance to imatinib, a selective receptor tyrosine kinase inhibitor (TKI), is a serious clinical problem in the control of advanced gastrointestinal stromal tumors (GIST). Here we report on a meta-analysis we performed to evaluate the efficacy of second-generation TKIs in the treatment of patients with imatinib-resistant GIST. Methods Randomized controlled trials evaluating the clinical efficacy of second-generation TKIs were identified by searching PubMed and EMBASE from 2000 to February 2014. Outcomes subjected to analysis were progression-free survival and overall survival. Statistical analyses were performed using Review Manager version 5.1.0 (Cochrane Collaboration, Oxford, UK). Weighted hazard ratios (HR) with 95% confidence intervals (CIs) were calculated for the outcomes. Fixed-effects or random-effects models were used, depending on the degree of heterogeneity across the selected studies. Results Three randomized controlled trials were selected for meta-analysis. Among imatinib-resistant or imatinib-intolerant patients, 541 received second-generation TKIs (sunitinib, nilotinib, or regorafenib) and 267 controls received placebo or best supportive care. Progression-free survival was significantly improved in the TKI-treated group (HR 0.38; 95% CI 0.24–0.59; P<0.0001). No statistically significant difference was detected in overall survival between the treatment group and the control group (HR 0.85; 95% CI 0.71–1.03; P=0.09). In the subgroup of patients who were resistant or intolerant to both imatinib and sunitinib, TKI therapy (nilotinib or regorafenib) improved progression-free survival (HR 0.40; 95% CI 0.19–0.84; P=0.02) but not overall survival (HR 0.83; 95% CI 0.63–1.08; P=0.17). Regorafenib was shown to be effective in terms of progression-free survival across different subpopulations of patients who were resistant to both imatinib and sunitinib. Conclusion Second-generation TKIs (sunitinib, nilotinib, and regorafenib) are effective in improving progression-free survival but not overall survival in patients with GIST who are resistant or intolerant to imatinib or to imatinib and sunitinib. Regorafenib is promising as a third-line treatment option for patients with advanced GIST.

Wild-type and mutant p53 differentially modulate miR-124/iASPP feedback following pohotodynamic therapy in human colon cancer cell line

Colorectal cancer (CRC) is a most common digestive system malignant tumor. p53 mutation has essential role in cancers and is frequently observed in CRC and presents a huge challenge. p53 mutation has been reported to attenuate the inhibitory effect of photofrin-based photodynamic therapy (PDT). p53 mutation-induced gain of function brings up the dysfunction of carcinogenic factors, including miRNAs. Our research found that PDT suppressed CRC cell viability, reduced the tumor size and prolonged the survival time, all of which could be attenuated by p53 mutation or deletion. After p53 mutation or deletion, several miRNA expression levels were downregulated, among which miR-124 was the most strongly downregulated, whereas iASPP expression was upregulated. p53 binds to the promoter of miR-124 to promote its expression and then inhibited iASPP expression, so as to amplify the inhibitory effect of PDT on wild-type p53 cells. In p53-mutant or -deleted cells, this binding no longer worked to promote miR-124 expression, and iASPP expression increased, finally resulted in promoted CRC cell viability upon PDT. The interactive modulation among miR and iASPP in p53-mutant or -deleted cells may serve as a crucial pathway, which mediates therapy resistance when p53 is mutated or deleted, in the process of PDT treatment of CRC.

Impact of a Eukaryotic Translation Initiation Factor 3a Polymorphism on Susceptibility to Gastric Cancer.

Objective: To investigate single nucleotide polymorphisms in the eukaryotic translation initiation factor 3a (eIF3a) gene and the risk for gastric cancer within the Chinese population. Subjects and Methods: A total of 322 patients with gastric cancer were selected as the patient group and 340 non-gastric cancer patients were selected as the control group using the case-control method. Polymerase chain reaction-sequence-specific primer technology was leveraged to genotype the rs77382849 single nucleotide polymorphism in the eIF3a gene. The demographic characteristics of the study population and other exposures to risk factors were collected. Unconditional logistic regression analysis was performed to determine the association between the risk factors and gastric cancer. Results: A higher frequency of the eIF3a rs77382849 GG homozygote genotype was observed in the gastric cancer patients compared with the controls (63.98 vs. 54.41%, p < 0.05). After adjustment of exposure risks, such as age, gender, smoking, and drinking, the rs77382849 single nucleotide polymorphism was still associated with susceptibility to gastric cancer. When the eIF3a rs77382849 GG homozygote genotype was used as the reference group, the GA genotype (GA vs. GG: OR = 0.545, 95% CI: 0.386-0.769, p = 0.001) and AA genotype (AA vs. GG: OR = 0.245, 95% CI: 0.072-0.836, p = 0.025) were both correlated with a significantly decreased risk for gastric cancer development. Conclusion: An association between eIF3a rs77382849 polymorphism and susceptibility to gastric cancer was observed in these Chinese patients.

Functional role of a long non-coding RNA LIFR-AS1/miR-29a/TNFAIP3 axis in colorectal cancer resistance to pohotodynamic therapy

Colorectal Cancer (CRC) is one of the most common digestive system malignant tumors. Recently, PDT has been used as a first-line treatment for colon cancer; however, limited curative effect was obtained due to resistance of CRC to PDT. During the past decades, accumulating CRC-related long non-coding RNAs (lncRNAs), microRNAs (miRNAs) and mRNAs have been reported to exert diverse functions through various biological processes; their dysregulation might trigger and/or promote the pathological changes. Herein, we performed microarrays analysis to identify dysregulated lncRNAs, miRNAs and mRNAs in PDT-treated HCT116 cells to figure out the lncRNA-miRNA interactions related to the resistance of CRC to PDT treatment, and the downstream mRNA target, as well as the molecular mechanism. We found a total of 1096 lncRNAs dysregulated in PDT-treated CRC HCT116 cells; among them, LIFR-AS1 negatively interacted with miR-29a, one of the dysregulated miRNAs in PDT-treated CRC cells, to affect the resistance of CRC to PDT. LIFR-AS1 knockdown attenuated, whereas miR-29a inhibition enhanced the cellular effect of PDT on HCT116 cell proliferation and apoptosis. Furthermore, among the dysregulated mRNAs, TNFAIP3 was confirmed to be a direct target of miR-29a and exerted a similar effect to LIFR-AS1 on the cellular effects of PDT. In summary, LIFR-AS1 serves as a competitive endogenous RNA (ceRNA) for miR-29a to inhibit its expression and up-regulate downstream target TNFAIP3 expression, finally modulating the resistance of CRC to PDT. We provide an experimental basis for this lncRNA/miRNA/mRNA network being a promising target in CRC resistance to PDT treatment.

The miR-124-p63 feedback loop modulates colorectal cancer growth

Among the diverse co-regulatory relationships between transcription factors (TFs) and microRNAs (miRNAs), feedback loops have received the most extensive research attention. The co-regulation of TFs and miRNAs plays an important role in colorectal cancer (CRC) growth. Here, we show that miR-124 can regulate two isoforms of p63, TAp63 and ΔNp63, via iASPP, while p63 modulates signal transducers and activators of transcription 1 (STAT1) expression by targeting miR-155. Moreover, STAT1 acts as a regulator of CRC growth by targeting miR-124. Taken together, these results reveal a feedback loop between miRNAs and TFs. This feedback loop comprises miR-124, iASPP, STAT1, miR-155, TAp63 and ΔNp63, which are essential for CRC growth. Moreover, this feedback loop is perturbed in human colon carcinomas, which suggests that the manipulation of this microRNA-TF feedback loop has therapeutic potential for CRC.

GNA13 promotes tumor growth and angiogenesis by upregulating CXC chemokines via the NF-κB signaling pathway in colorectal cancer cells

GNA13 has been found overexpressed in various types of cancer, which is related to tumor metastasis and progression. However, the biological functions of GNA13 in colorectal cancer (CRC) progression remain unclear. This study aimed to explore the role of GNA13 in CRC and investigate the mechanism of how GNA13 promotes tumor growth. Interestingly, our findings showed that GNA13 is commonly upregulated in CRC, where these events are associated with a worse histologic grade and poor survival. Increased expression levels of GNA13 promoted cell growth, migration, invasion, and epithelial‐mesenchymal transition, whereas GNA13 silencing abrogated these malignant phenotypes. In addition, overexpressing GNA13 in cancer cells increased the levels of the chemokines CXCL1, CXCL2, and CXCL4, which contributed to CRC proliferation and colony formation. Moreover, our mechanistic investigations suggest that the NF‐κB/p65 signaling pathway was activated by the increase in GNA13 levels. Inhibiting the NF‐κB/p65 pathway with an inhibitor decreased GNA13‐induced migration, invasion and CXCL chemokine level increases, indicating the critical role of NF‐κB/p65 signaling in mediating the effects of GNA13 in CRC. Together, these results demonstrate a key role of GNA13 overexpression in CRC that contributes to malignant behavior in cancer cells, at least in part through stimulating angiogenesis and increasing the levels of the NF‐κB‐dependent chemokines CXCL1, CXCL2, and CXCL4.

Tim-4 promotes the growth of colorectal cancer by activating angiogenesis and recruiting tumor-associated macrophages via the PI3K/AKT/mTOR signaling pathway

T-cell immunoglobulin domain and mucin domain-4 (Tim-4) is overexpressed in several tumors and is correlated with enhanced tumor development and metastasis. In this study, we investigated the physiological alterations and molecular events related to Tim-4 overexpression in a mouse model of colorectal cancer (CRC). In the current study, we observed that Tim-4 is upregulated in CRC tissues compared with neighboring normal tissues. In addition, statistical analysis revealed that elevated Tim-4 expression was strongly linked to distant metastasis, TNM stage and reduced overall survival duration in CRC patients. An orthotopic model was employed to explore the function of Tim-4 in CRC development through the implantation of Tim-4-overexpressing CT26 murine colon adenocarcinoma cells. It was observed that Tim-4 overexpression considerably enhanced CRC tumorigenesis in vivo and promoted angiogenesis through the upregulation of vascular endothelial growth factor (VEGF). In CT26 cells, Tim-4 overexpression increased the aldehyde dehydrogenase-1 (ALDH1) level, indicating an increase in cancer stem cell (CSC)-like properties. Furthermore, we determined that Tim-4 activates PI3K/AKT/mTOR signaling in CRC cells. Tim-4-overexpressing cancer cells recruited tumor-associated macrophages (TAMs), thereby accelerating cancer development. Therefore, our results strongly indicate that Tim-4 overexpression promotes proliferation and tumor stroma remodeling in CRC. PI3K/AKT/mTOR activation might be crucial in Tim-4-linked tumor development. This finding might offer a new strategy for therapeutic intervention.