Circ6834 suppresses non-small cell lung cancer progression by destabilizing ANHAK and regulating miR-873-5p/TXNIP axis.

BACKGROUND: Circular RNAs (circRNAs) play important roles in cancer progression and metastasis. However, the expression profiles and biological roles of circRNAs in non-small cell lung cancer (NSCLC) remain unclear. METHODS: In this study, we identified a novel circRNA, hsa_circ_0006834 (termed circ6834), in NSCLC by RNA-seq and investigated the biological role of circ6834 in NSCLC progression in vitro and in vivo. Finally, the molecular mechanism of circ6834 was revealed by tagged RNA affinity purification (TRAP), western blot, RNA immunoprecipitation, dual luciferase reporter gene assays and rescue experiments. RESULTS: Our results showed that circ6834 was downregulated in NSCLC tumor tissues and cell lines. Circ6834 overexpression inhibited NSCLC cell growth and metastasis both in vitro and in vivo, while circ6834 knockdown had the opposite effect. We found that TGF-ß treatment decreased circ6834 expression, which was associated with the QKI reduction in NSCLC cells and circ6834 antagonized TGF-ß-induced EMT and metastasis in NSCLC cells. Mechanistically, circ6834 bound to AHNAK protein, a key regulator of TGF-ß/Smad signaling, and inhibited its stability by enhancing TRIM25-mediated ubiquitination and degradation. In addition, circ6834 acted as a miRNA sponge for miR-873-5p and upregulated TXNIP gene expression, which together inactivated the TGF-ß/Smad signaling pathway in NSCLC cells. CONCLUSION: In conclusion, circ6834 is a tumor-suppressive circRNA that inhibits NSCLC progression by forming a negative regulatory feedback loop with the TGF-ß/Smad signaling pathway and represents a novel therapeutic target for NSCLC.

Circular RNAs as biomarkers and therapeutic targets for gastrointestinal cancers.

Circular RNAs are a class of noncoding RNAs with covalently linked 5' and 3' ends that arise from backsplicing events. The absence of a 5' cap and a 3' poly(A) tail makes circular RNAs relatively more stable than their linear counterparts. They are evolutionary conserved and tissue-specific, and some show disease-specific expression patterns. Although their biological functions remain largely unknown, circular RNAs have been shown to play regulatory roles by acting as microRNA sponges, regulators of RNA-binding proteins, alternative splicing, and parental gene expression, and they could even encode proteins. Over the past few decades, circular RNAs have attracted wide attention in oncology owing to their implications in various tumors. Many circular RNAs have been characterized as key players in gastrointestinal cancers and influence cancer growth, progression, metastasis, and therapeutic resistance. Accumulating evidence reveals that their unique characteristics, coupled with their critical roles in tumorigenesis, make circular RNAs promising non-invasive clinical biomarkers for gastrointestinal cancers. In the present review, we summarized the biological roles of the emerging circular RNAs and their potential as biomarkers and therapeutic targets, which may help better understand their clinical significance in the management of gastrointestinal cancers.

Current status of clinical trial research and application of immune checkpoint inhibitors for non-small cell lung cancer.

Immunotherapy has emerged as a hot topic in the treatment of non-small cell lung cancer (NSCLC) with remarkable success. Compared to chemotherapy patients, the 5-year survival rate for immunotherapy patients is 3-fold higher, approximately 4%-5% versus 15%-16%, respectively. Immunotherapies include chimeric antigen receptor T-cell (CAR-T) therapy, tumor vaccines, immune checkpoint inhibitors, and so forth. Among them, immune checkpoint inhibitors are in the spotlight. Common immune checkpoint inhibitors (ICIs) currently in clinical use include programmed death receptor-1(PD-1)/programmed death ligand-1(PD-L1) and cytotoxic T lymphocyte-associated antigen 4(CTLA-4). This article focuses on monotherapy and combination therapy of CTLA-4 and PD-1/PD-L1 immune checkpoint inhibitors. In particular, the combination therapy of ICIs includes the combination of ICIs and chemotherapy, the combination therapy of dual ICIs, the combination of ICIs and anti-angiogenic drugs, the combination of ICIs and radiotherapy, and the combination of ICIs inhibitors and tumor vaccines and so forth. This article focuses on the combination therapy of ICIs with chemotherapy, the combination therapy of dual ICIs, and the combination therapy of ICIs with anti-angiogenic drugs. The efficacy and safety of ICIs as single agents in NSCLC have been demonstrated in many trials. However, ICIs plus chemotherapy regimens offer significant advantages in the treatment of NSCLC with little to no dramatic increase in toxicity, while combined dual ICIs significantly reduce the adverse effects (AEs) of chemotherapy. ICIs plus anti-angiogenic agents regimen improves anti-tumor activity and safety and is expected to be the new paradigm for the treatment of advanced NSCLC. Despite some limitations, these agents have achieved better overall survival rates. In this article, we review the current status and progress of research on ICIs in NSCLC in recent years, aiming to better guide the individualized treatment of NSCLC patients.

PIEZO2 promotes cell proliferation and metastasis in colon carcinoma through the SLIT2/ROBO1/VEGFC pathway.

BACKGROUND: The PIEZO2 may be involved in the occurrence and development of tumors. OBJECTIVES: To explore the potential mechanism and effect of PIEZO2 on colon cancer. MATERIAL AND METHODS: We assessed the expression and prognostic role of PIEZO2 in patients with colon cancer. The role of PIEZO2 in SW480 cell proliferation, migration and invasion in vitro was investigated using cell counting kit-8 (CCK-8), wound healing, and transwell and cell invasion assays, respectively. The effect of PIEZO2 on SW480 cells in vivo was also explored. The potential mechanisms of PIEZO2 in SW480 cells were detected using quantitative reverse-transcription polymerase chain reaction (qRT-PCR) and western blot. RESULTS: The PIEZO2 was significantly increased in colon cancer tissues and the PIEZO2 high expression group was associated with a lower overall survival (OS) rate. Furthermore, PIEZO2 knockdown weakened the proliferation, migration and invasion of SW480 cells. The PIEZO2 knockdown was related to a lower expression of SLIT2, ROBO1, HIF-1α, and VEGFC. Finally, the tumors in control SW480 cells grew faster and larger than those in mice inoculated with si-PIEZO2 SW480 cells. Moreover, the si-PIEZO2 SW480 cell group showed a reduced expression of Ki67 and VEGFC and, at the same time, a significantly higher apoptosis index of tumor cells compared to the control group. The expression of PIEZO2 was higher in cancer-associated fibroblasts (CAFs) of colon cancer. CONCLUSIONS: The PIEZO2 was increased in colon cancer tissues and was an unfavorable gene in patients with colon cancer, promoting colon cell proliferation, migration and invasion through the SLIT2/ROBO1/VEGFC pathway.

Extracellular Vesicles in Cancer Drug Resistance: Roles, Mechanisms, and Implications.

Extracellular vesicles (EVs) are cell-derived nanosized vesicles that mediate cell-to-cell communication via transporting bioactive molecules and thus are critically involved in various physiological and pathological conditions. EVs contribute to different aspects of cancer progression, such as cancer growth, angiogenesis, metastasis, immune evasion, and drug resistance. EVs induce the resistance of cancer cells to chemotherapy, radiotherapy, targeted therapy, antiangiogenesis therapy, and immunotherapy by transferring specific cargos that affect drug efflux and regulate signaling pathways associated with epithelial-mesenchymal transition, autophagy, metabolism, and cancer stemness. In addition, EVs modulate the reciprocal interaction between cancer cells and noncancer cells in the tumor microenvironment (TME) to develop therapy resistance. EVs are detectable in many biofluids of cancer patients, and thus are regarded as novel biomarkers for monitoring therapy response and predicting prognosis. Moreover, EVs are suggested as promising targets and engineered as nanovehicles to deliver drugs for overcoming drug resistance in cancer therapy. In this review, the biological roles of EVs and their mechanisms of action in cancer drug resistance are summarized. The preclinical studies on using EVs in monitoring and overcoming cancer drug resistance are also discussed.

Exosomes as a new frontier of cancer liquid biopsy.

Liquid biopsy, characterized by minimally invasive detection through biofluids such as blood, saliva, and urine, has emerged as a revolutionary strategy for cancer diagnosis and prognosis prediction. Exosomes are a subset of extracellular vesicles (EVs) that shuttle molecular cargoes from donor cells to recipient cells and play a crucial role in mediating intercellular communication. Increasing studies suggest that exosomes have a great promise to serve as novel biomarkers in liquid biopsy, since large quantities of exosomes are enriched in body fluids and are involved in numerous physiological and pathological processes. However, the further clinical application of exosomes has been greatly restrained by the lack of high-quality separation and component analysis methods. This review aims to provide a comprehensive overview on the conventional and novel technologies for exosome isolation, characterization and content detection. Additionally, the roles of exosomes serving as potential biomarkers in liquid biopsy for the diagnosis, treatment monitoring, and prognosis prediction of cancer are summarized. Finally, the prospects and challenges of applying exosome-based liquid biopsy to precision medicine are evaluated.

Engineered neutrophil-derived exosome-like vesicles for targeted cancer therapy.

Neutrophils are the most abundant innate immune cells in human circulation; however, their derived exosomes have been rarely studied for tumor treatment. Here, we reported that exosomes from neutrophils (N-Ex) induce tumor cell apoptosis by delivering cytotoxic proteins and activating caspase signaling pathway. In addition, we decorated N-Ex with superparamagnetic iron oxide nanoparticles (SPIONs) to achieve higher tumor-targeting therapeutic effect. We further fabricated exosome-like nanovesicles from neutrophils (NNVs) at high yield. Compared with liposome-loaded doxorubicin (DOX) and natural NNVs, DOX-loaded NNVs show an improved inhibition of tumor cell proliferation. Moreover, DOX-loaded, SPION-decorated NNVs selectively accumulate at the tumor sites under an external magnetic field, effectively restraining tumor growth and extensively prolonging the survival rate in mice. Overall, a simple and effective method to engineer N-Ex and NNVs at clinical applicable scale was developed, which enables the efficient and safe drug delivery for targeted and combined tumor therapy.

Long Non-coding RNA DANCR in Cancer: Roles, Mechanisms, and Implications.

Long non-coding RNA (lncRNA) DANCR (also known as ANCR)-differentiation antagonizing non-protein coding RNA, was first reported in 2012 to suppress differentiation of epithelial cells. Emerging evidence demonstrates that DANCR is a cancer-associated lncRNA abnormally expressed in many cancers (e.g., lung cancer, gastric cancer, breast cancer, hepatocellular carcinoma). Increasing studies suggest that the dysregulation of DANCR plays critical roles in cancer cell proliferation, apoptosis, migration, invasion, and chemoresistance in vitro and tumor growth and metastasis in vivo. Mechanistic analyses show that DANCR can serve as miRNA sponges, stabilize mRNAs, and interact with proteins. Recent research reveals that DANCR can be detected in many body fluids such as serum, plasma, and exosomes, providing a quick and convenient method for cancer monitor. Thus DANCR can be used as a promising diagnostic and prognostic biomarker and therapeutic target for various types of cancer. This review focuses on the role and mechanism of DANCR in cancer progression with an emphasis on the clinical significance of DANCR in human cancers.

Efficacy and Safety of Programmed Cell Death 1 Inhibitor Monotherapy Versus Chemotherapy as Second-Line Treatment for Advanced Esophageal Cancer: A Meta-analysis and Systematic Review.

PURPOSE: With programmed cell death 1 (PD-1) inhibitors approved for second-line treatment of advanced esophageal cancer, immunotherapy and chemotherapy have gradually become the main treatments for second-line treatment of patients with advanced esophageal cancer (AEC). This meta-analysis and systematic review were conducted to evaluate the efficacy and safety of PD-1 inhibitors monotherapy versus chemotherapy in second-line treatment of AEC. METHODS: Eligible randomized controlled trials were searched in PubMed, Embase, and the Cochrane Library and abstracts presented at the American Society of Clinical Oncology or European Society of Medical Oncology were reviewed to assess the efficacy and tolerability of PD-1/programmed cell death ligand 1 (PD-L1) inhibitors relative to chemotherapy for AEC from January 2016 to October 2020. Patients diagnosed with AEC and progressing after first-line therapy were included in this study. Hazard ratios (HRs) of progression-free survival (PFS) and overall survival (OS), risk ratios (RRs) of objective response rate (ORR), and the odds ratios (ORs) of adverse effects (AEs) were calculated. FINDINGS: The study included 4 randomized controlled trials with 1683 patients. The results indicated that PD-1 inhibitors prolonged the OS (HR = 0.79; 95% CI, 0.71-0.88; P < 0.01) and improved the ORR (RR = 3.00; 95% CI, 2.36-3.82; P = 0.01) but did not improve the PFS (HR = 0.96; 95% CI, 0.76-1.20; P = 0.692) compared with chemotherapy in the second-line treatment of AEC. PD-1 inhibitors alone were associated with a lower incidence of all treatment-related AEs (OR = 0.29; 95% CI, 0.09-0.89; P = 0.03) and grade 3 to 5 treatment-related AEs (OR = 0.26; 95% CI, 0.16-0.44; P < 0.01) versus chemotherapy. PD-1 inhibitors prolonged OS mainly in the following patient groups: male, age <65 years, Eastern Cooperative Oncology Group performance status of 1, or PD-L1 tumor proportion score ≥10%. Asian patients had a longer OS than non-Asian patients (P = 0.01). IMPLICATIONS: The available evidence indicates that the efficacy and tolerability of PD-1 inhibitors were better than chemotherapy in the second-line treatment of AEC, and the benefiting population of these patients was limited to males, those <65 years of age, those with a Eastern Cooperative Oncology Group performance status of 1, or those with a PD-L1 tumor proportion score ≥10%. Notably, Asian patients receiving immune monotherapy had longer OS than non-Asian patients.

CircDIDO1 inhibits gastric cancer progression by encoding a novel DIDO1-529aa protein and regulating PRDX2 protein stability.

BACKGROUND: Circular RNAs (circRNAs) play important roles in cancer development and progression. The purpose of this study is to identify aberrantly expressed circRNAs in gastric cancer (GC), unravel their roles in GC progression, and provide new targets for GC diagnosis and therapy. METHODS: Bioinformatic analyses were performed to identify the aberrantly expression of hsa_circ_0061137 (termed as circDIDO1) in GC. Gain- and loss-of-function studies were performed to examine the biological roles of circDIDO1 in GC progression. Tagged RNA affinity purification, mass spectrometry, immunofluorescence, co-immunoprecipitation, and Western blot were used to identify circRNA-interacting and circRNA-encoded proteins. RNA sequencing, qRT-PCR, and Western blot were performed to analyze circRNA-regulated downstream target genes and signaling pathways. Mouse tumor models were used to analyze the effects of circDIDO1 on GC growth and metastasis. RESULTS: CircDIDO1 was transcribed from human DIDO1 (death-inducer obliterator 1) gene and formed by back-splicing of exons 2-6 of the linear transcript. circDIDO1 was down-regulated in GC tissues and its low levels were associated with larger tumor size, distal metastasis, and poor prognosis. CircDIDO1 overexpression inhibited while knockdown promoted GC cell proliferation, migration and invasion. CircDIDO1 overexpression suppressed GC growth and metastasis in mouse tumor models. Mechanistically, circDIDO1 encoded a novel 529aa protein that directly interacted with poly ADP-ribose polymerase 1 (PARP1) and inhibited its activity. CircDIDO1 also specifically bound to peroxiredoxin 2 (PRDX2) and promoted RBX1-mediated ubiquitination and degradation of PRDX2, which led to the inactivation of its downstream signaling pathways. CONCLUSIONS: CircDIDO1 is a new circRNA that has tumor suppressor function in GC and it may serve as a potential prognostic biomarker and therapeutic target for GC.

Efficacy of trastuzumab combined with SOX or IP chemotherapy regimen in the treatment of advanced gastric cancer.

PURPOSE: The purpose of this study was to compare the clinical efficacy and safety of S-1 + oxaliplatin (SOX) chemotherapy regimen combined with trastuzumab and irinotecan + cisplatin (IP) chemotherapy regimen combined with trastuzumab in treating human epidermal growth factor receptor 2 (HER-2)-positive advanced gastric cancer. METHODS: A total of 138 patients with HER-2-positive advanced gastric cancer were divided into SOX group (SOX chemotherapy regimen combined with trastuzumab; n=69) and IP group (IP chemotherapy regimen combined with trastuzumab; n=69). Then, the clinical efficacy, incidence rate of adverse reactions, quality-of-life score and other indicators were compared between the two groups of patients. Additionally, the levels of myeloid-related protein-14 (MRP-14), stromal cell-derived factor-1 (SDF-1), fibroblast-specific protein-1 (FSP-1) and CXC chemokine receptor-4 (CXCR4) in peripheral blood and the changes in neovascularization markers were detected, and the survival of patients was followed up and recorded. RESULTS: The disease control rate (DCR) was clearly better in SOX group than that in IP group. Serum levels of MRP-14, SDF-1, FSP-1 and CXCR4 were obviously lower in SOX group than those in IP group. The scores of physical function, behavioral function, role function and social function were higher in SOX group than those in IP group. Moreover, the follow-up results revealed that the PFS of patients was overtly longer in SOX group than that in IP group. CONCLUSIONS: Trastuzumab combined with SOX chemotherapy regimen has an obvious curative effect in the treatment of advanced gastric cancer, which prominently improves the quality of life of patients, lowers the serum tumor marker levels in patients, delays tumor progression, and results in tolerable adverse reactions. Therefore, it is worthy of application in clinical practice.

Comparative efficacy and safety of PD-1/PD-L1 Inhibitors versus platinum-based chemotherapy for the first-line treatment of advanced non-small cell lung cancer: a meta analysis of randomized controlled trials.

OBJECTIVE: The main aim of this study was to systematically evaluate the efficacy and safety of inhibitors of programmed cell death receptor 1 (PD-1) and its ligand, programmed cell death ligand-1 (PD-L1), in the treatment of advanced non-small cell lung cancer (NSCLC). METHODS: Randomized controlled trials assessing the efficacy of PD-1/PD-L1 inhibitors relative to platinum-based chemotherapy for advanced NSCLC in PubMed, EMBASE, and Cochrane libraries from 2015 to 2020 were searched, along with review of studies at American Society of Clinical Oncology (ASCO) and European society for Medical Oncology (ESMO). Pooled hazard ratios (HR) for progression-free survival (PFS) and overall survival (OS) and odds ratios (OR) for adverse events (AE) were calculated using STATA and Revman software. RESULTS: PD-1/PD-L1 inhibitors alone or combined with chemotherapy significantly improved OS (HR = 0.82, 95% CI:0.74-0.91, P = 0.01 or HR = 0.74, 95% CI:0.67-0.82, P = 0.001). PD-1/PD-L1 inhibitors alone did not benefit PFS (HR = 0.99, 95% CI: 0.89-1.10, P = 0.892), while combination therapy led to prolonged PFS (HR = 0.61, 95% CI: 0.56-0.67, P < 0.001). Subgroup analysis showed that in NSCLC with PD-L1 ≥ 50%, treatment with PD-1/PD-L1 inhibitors alone significantly improved both PFS and OS. In patients subjected to the combined treatment regimen, we observed significant differences in PFS among groups stratified by PD-L1 expression (p < 0.001), immune drug type (p = 0.029), gender (p = 0.014) and liver metastasis (p = 0.035) and OS among groups stratified by immune drug type (p < 0.001), gender (P = 0.001) and smoking status (P = 0.041). Safety analysis showed that combination therapy increased chemotherapy-induced adverse events (AE), while PD-1/PD-L1 inhibitors alone were associated with a lower incidence of any grade of treatment-related AEs (TRAE). A higher incidence of Grade 3-5 TRAEs and hypothyroidism was observed with PD-1 inhibitors than PD-L1 inhibitors. CONCLUSIONS: First-line treatment of advanced NSCLC with immune monotherapy or immunochemotherapy confers a greater survival benefit than chemotherapy alone. Combination of chemotherapy with PD-1/PD-L1 inhibitors leads to an increase in adverse events, and PD-1 inhibitors offer enhanced survival benefits and fewer adverse events than PD-L1 inhibitors. Remarkably, female patients undergoing combination therapy had longer overall survival than male patients.

Perioperative blood transfusion is one of the factors that affect the prognosis of gastric cancer.

PURPOSE: To demonstrate the potential significance of perioperative blood transfusion on the prognosis of gastric cancer. METHODS: Data from 234 patients who were subjected to radical gastrectomy in our hospital were obtained and retrospectively analyzed. Patients' age, gender, preoperative anemia, tumor size, location, invasion depth, lymph node metastasis, TNM stage, presence or absence of blood transfusion and blood transfusion volume were observed and analyzed. RESULTS: The difference of tumor recurrence in patients whose blood transfusion volume was greater than 2U was significant (p<0.001). The tumor recurrence in patients whose blood transfusion was less than 2U was significantly shorter than in those whose transfusion volume was greater than 4U (p=0.03). The survival in the blood transfusion group was significantly lower in comparison with the nonblood transfusion group (p=0.002). The survival of transfusion group in TNM stage III and IV was significantly shorter than that in non-transfusion group (p=0.03). Statistical significance was found in survival between the transfusion group and non-transfusion group when the tumor size was less than 5 cm and greater than 5 cm (p=0.006, p=0.04, respectively). CONCLUSIONS: Perioperative transfusion is one of the factors for predicting the prognosis of postoperative gastric cancer patients, and the larger the perioperative transfusion, the shorter the tumor recurrence, the worse the prognosis. Therefore, it is of great significance reducing the intraoperative blood loss and strict controlling blood transfusion indications.

Polymorphisms in thymidylate synthase and reduced folate carrier (SLC19A1) genes predict survival outcome in advanced non-small cell lung cancer patients treated with pemetrexed-based chemotherapy.

The aim of this study was to evaluate the association between thymidylate synthase (TS), methylenetetrahydrofolate reductase (MTHFR) and reduced folate carrier (SLC19A1) gene polymorphisms and the treatment efficacy of pemetrexed-based chemotherapy in advanced non-small cell lung cancer (NSCLC). Advanced NSCLC patients received pemetrexed and cisplatin every three weeks. Polymorphisms in the TS, MTHFR and SLC19A1 genes were detected in peripheral blood samples using DNA sequencing and Taqman PCR. An analysis of gene polymorphisms was performed with respect to the progression-free survival (PFS), response rate (RR) and overall survival (OS) of patients treated with pemetrexed. The median PFS times for patients with the TS 2R/2R, 2R/3C or 3C/3C genotypes were significantly longer than those of patients with the 2R/3G, 3C/3G or 3G/3G genotypes (P=0.036). Patients with the SLC19A1 CC genotype had a significantly longer median OS compared with individuals with the homozygous and heterozygous genotypes (12.2 vs. 8.9 and 7.3 months, respectively; P=0.022). The PFS and OS did not differ for the three genotypes of MTHFR assessed. The RR was higher in patients with the TS 2R/2R, 2R/3C or 3C/3C genotypes than in the other groups (P=0.044). The polymorphisms of the 5'-UTR of the TS gene and exon 6 (2522) C/T of the SLC19A1 gene predict the survival of advanced NSCLC patients treated with pemetrexed. However, a large scale clinical trial is required to validate these findings.

[Influence of YB-1 protein on the biological behaviour in K562/A02 cells].

The aim of this study was to investigate whether the growth, apoptosis and sensitivity to anticancer agent could be altered after introduction of YB-1 shRNA eukaryotic expression vector into the K562/A02 cells, and its possible molecular mechanisms. The recombinant eukaryotic expression plasmids including YB-1 shRNA and the vector-random-sequence were introduced into K562/A02 cells by lipofectamine mediation, and the positive clones were screened by G418. RT-PCR and Western blot were employed to detect the expression of mRNA and protein of YB-1 in leukemia cells, respectively. The proliferative ability of the cells was determined by MTT assay and cell cycle analysis. Apoptosis of K562/A02 cells was assayed by AnnexinV-FITC/PI double labeled flow cytometry. The drug sensitivity to anticancer agent was determined by MTT assay. The expressions of MDR1 gene and P-gp were detected by RT-PCR and flow cytometry respectively. The results indicated that the levels of mRNA and protein of YB-1 decreased dramatically in three groups of positively transfected cells when compared with control cells. The inhibitory rates of 3 different shRNA sequences targeting YB-1 gene were (65.1 ± 2.1)%, (27.4 ± 1.3)% and (67.4 ± 1.6)% respectively. The introduction of exogenous YB-1 shRNA gene into K562/A02 cells resulted in decreased levels of the proliferative ability in K562/A02 cells, and displayed higher at G(1), lower at G(2) and S phase in cell cycle distribution in comparison with the control groups. AnnexinV/PI detection indicated higher AnnexinV(+) ratio in 3 groups of positively transfected cells after being treated with As(2)O(3) of 0.5 µmol/L for 24 hours. The IC(50) values of doxorubicin in 3 groups of positively transfected cells were significantly lower than that in control group. The level of MDR1 gene and P-gp decreased significantly in 3 groups of positively transfected cells. It is concluded that the transfection with YB-1 shRNA gene can inhibit the proliferation of leukemia cells and induce cell apoptosis. The expression of MDR1 mRNA and P-gp decrease after transfection of YB-1 shRNA into K562/A02 cells.

[VEGF shRNA enhances the sensitivity of multidrug-resistant leukemia cells to anticancer agent].

This study was aimed to explore the effect of vascular endothelial growth factor (VEGF) on sensitivity of leukemia cell line K562/A02 to doxorubicin by using RNA interference, and to investigate its mechanism. The 3 shRNA targeting human vegf gene were synthesized, then transfected into K562/A02 cells by lipofectamine 2000 reagent. RT-PCR was used to detect the expression of vegf and mrp1 at the mRNA level;Western blot was used to analyze the expression of VEGF, MRP1, AKT, P-AKT at the protein level; MTT was used to determine the IC(50) value of transfected cells to doxorubicin (DOX); flow cytometry was used to detect cell apoptosis and intracellular Rho123 retention. The results showed that after vegf shRNA were transfected into K562/A02 cells, the expression of vegf at the mRNA level decreased, and the difference between vegf shRNA2 group or vegf shRNA3 group and HK group was statistically significant (p < 0.05), the greatest decrease was observed in the cells transfected with vegf shRNA3; and the protein level of VEGF was also down-regulated. The IC(50) value of positively transfected group was lower than that of control groups, and the difference between vegf shRNA2 group or vegf shRNA3 group and HK group was significant (p < 0.05). The retention of intracellular Rho123 was enhanced in three positively transfected groups (p < 0.05). Cell apoptosis increased in positively transfected groups, and there was statistically difference between vegf shRNA2 group or vegf shRNA3 group and HK group (p < 0.05). The expression of mrp1 at the mRNA level were decreased, and there were statistical difference between vegf shRNA3 group and HK group (p < 0.05), and the protein level of mrp1 was also down-regulated; the expression of P-AKT at protein level decreased in positively transfected groups, and the greatest decrease was seen in vegf shRNA3 group. It is concluded that the transfection with exogenous vegf shRNA can inhibit the expression of vegf at both mRNA and protein levels, and enhance the sensitivity of K562/A02 cell to doxorubicin, the mechanism of which may be the inhibition of apoptosis and down-regulation of MRP1 by inactivating PI3K/AKT signaling pathway.

[CD44 variant increases the invasive ability of human breast cancer cell line MCF-7 cells].

OBJECTIVE: To evaluate the impact of a new CD44 variant on invasion of human breast cancer cell line MCF-7, and its possible mechanisms. METHODS: The full length cDNA encoding CD44v17 was obtained from the total RNA isolated from the MCF-7/ADR cells by reverse transcript-polymerase chain reaction (RT-PCR) and subcloned into pMD19-T vector. The CD44v17 gene sequence and reading frame were confirmed by two restriction enzymes and nucleotide sequencing, and then inserted into the eukaryotic expression vector pcDNA3.1. The pcDNA3.1-CD44v17 was transfected into MCF-7 cells by Lipofectamine. The changes of MMP-2 and MMP-9 expression at gene and protein levels were detected by RT-PCR and gelatin zymography, respectively. The number of the cells through the artificial matrix membrane in every group was counted to compare the change of the invasive ability regulated by CD44 variant. The ERK and p-ERK were investigated by Western blotting to approach the molecular mechanisms of MMP-2 and MMP-9 expression regulated by CD44 variant. RESULTS: The new gene sequence was successfully cloned into recombinant vector pcDNA3.1 and identified by the two restriction enzymes. It was confirmed that the reconstructed plasmid contained the sequence of CD44 gene variant which was composed of 1 to 4 exons, 16 to 17 exons, and 1 to 205 bases of 18 exons. The new gene sequence was sent to NCBI for publication and obtained the registered number FJ216964. The up-regulated levels of the CD44 gene mRNA and protein were respectively detected by RT-PCR and flow cytometry in MCF-7 cells transfected with pcDNA3.1-CD44v17. The invasiveness of the cells and the activity of MMP-2 and MMP-9 were clearly activated by hyaluronic acid (HA) treatment and blocked by CD44 neutralizing antibody. Pretreated MCF-7/CD44v17 cells with the neutralizing antibody against CD44 and the inhibitor of MAPKs signaling pathway strongly block the expression of p-ERK. CONCLUSION: A new CD44 gene variant has been found in adriamycin-resistant human breast cancer MCF-7/ADR cells. The expression vector pcDNA3.1-CD44v17 has been cloned and constructed successfully. HA can be integrated with CD44 variant and then regulates the expression of MMP-2 and MMP-9, which increases the invasion ability of MCF-7 cells through the Ras/MAPK signaling pathway.

[Effect of YB-1 gene knockdown on human leukemia cell line K562/A02].

OBJECTIVE: To investigate the potential effects of YB-1 gene knockdown on gene expression profile, cell growth and apoptosis in leukemia cell line K562/A02. METHODS: The recombinant eukaryotic expression plasmid containing YB-1 short hairpin RNA (shRNA) or random-sequence (HK) were transfected into K562/A02 cells by lipofectamine mediation. cDNA microarray was performed to explore the alteration of gene expression profile when YB-1 gene expression was decreased. Expression of CARD8 and RHOC genes were verified by semi-quantitative reverse transcription-PCR (RT-PCR). The proliferative ability of the cells was determined by methyl thiazolyltetrazolium (MTT) assay and cell cycle analysis. Cell apoptosis was assayed by Annexin V-FITC/PI double labeled flow cytometry. RESULTS: The levels of YB-1 mRNA and protein decreased dramatically in three positively transfected cells when compared with untransfected K562/A02 cells or K562/A02-HK thansfected cells. Gene expression profile was altered by transfection of YB-1 shRNA into K562/A02 cells. Among 47,000 genes on the microarray, 252 genes were detected to have changes, with 143 down-regulated and 109 up-regulated. They were functionally related to cell cycle progression, gene replication, metabolism, cell apoptosis, cell signal transduction, etc. An increase in CARD8 gene expression and a decrease in RHOC gene expression have been confirmed by RT-PCR in K562/A02-YBX13 cells. The introduction of exogenous YB-1 shRNA gene into K562/A02 cells resulted in decreased proliferation, higher G1, lower G2 and S ratio in cell cycle distribution in comparison with the control groups. Annexin V/PI detection indicated higher Annexin V+ ratio in the three positively transfected cells 24 hours after cells were treated with 0.5 micromol/L of As2O3. CONCLUSION: Down-regulation of YB-1 gene by shRNA-YB-1 can alter the gene expression profile in K562/A02 cells, leading to change of cell proliferation and apoptosis.