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.

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.

Effect of CD44st and HER2 expression on the postoperative prognosis of breast cancer patients.

OBJECTIVE: CD44st is a member of the CD44 family; abnormal expression of some CD44 isoforms are closely associated with axillary lymph node metastasis, cancer progression, and patients' prognosis. The objective of this study is to investigate the correlation between the expression of CD44st and HER2 in breast cancer and the effect on patients' prognosis. METHODS: Primers were designed to target the CD44st mRNA (Gene Bank No FJ216964) which has been newly identified in a drug-resistant breast cancer cell line. The expression of CD44st and HER2 mRNA and proteins in cancerous and paracancerous tissue of postoperative breast cancer patients was detected and compared. Tissue samples were obtained from 102 cases of invasive ductal carcinoma, 19 cases of intraductal carcinoma, and 11 cases of medullary carcinoma. The correlation between CD44st and HER2 expression and clinical pathological features was examined. RESULTS: The expression rate of CD44st mRNA and protein in breast cancer tissue was 64.4% (85/132), while HER2 mRNA and protein was expressed in 22.0% (29/106) of the samples. The expression of CD44st and HER2 were low in paracancerous tissue. In breast cancer tissue, the expression rate of HER2 mRNA and protein in the CD44st-positive group was 28.2% (24/85), and 10.6% (5/47) in the CD44st-negative group. This difference was statistically significant (P=0.015). Sequencing analysis showed that the amplified CD44st gene in this study was the same as that which was previously discovered in the drug-resistant breast cancer cell line. A linear correlation was found between the expression of CD44st and HER2 (r=0.972, r2=0.945, F=2,213.51, P<0.001). The expression of CD44st and HER2 was also closely associated with luminal cancer subtypes, lymph node metastasis, and TNM stage (P<0.05), but not associated with age, pathological type, or tumor size (P>0.05). The median overall survival in the CD44st high-expression group was 51.85 months (95% CI: 48.48-55.22), which was significantly shorter than that in the CD44st low-expression group (57.61 months; 95% CI: 55.54-59.68, P=0.032). CONCLUSION: CD44st is closely related to the expression of HER2. The expression of CD44st affects patient prognosis and is associated with lymph node metastasis, TNM staging, and molecular subtyping.

A correlation study of the expression of HA-CD44st and HER-2 in breast cancer.

BACKGROUND: This study investigated the effect of hyaluronic acid (HA)-CD44st on the invasive ability of human breast cancer MCF-7 cells and the correlation between the expression of CD44st and human epidermal growth factor receptor-2 (HER-2) in postoperative breast cancer patients. MATERIALS AND METHODS: MCF-7 cells transfected with the eukaryotic expression vector pcDNA3.1-CD44st (MCF/CD44st) were used to examine the effect of the activation of the HA-CD44st-transforming growth factor ß (TGFß)-phosphatidylinositol-3-kinase (PI3K) signaling pathway on the invasive ability of MCF-7 cells. The expression of proteins related to this signaling pathway was assessed by flow cytometry, reverse transcription-polymerase chain reaction, and Western blotting, and the role of AP-1 in the pathway was investigated by electrophoretic mobility shift assay. The effect of pathway activation on the invasion of MCF-7 cells was assessed by Transwell assay, and CD44 expression in breast cancer tissue was detected by immunohistochemistry. Quantitative reverse transcription-polymerase chain reaction was used to detect the expression of CD44st and HER-2 in breast cancer tissue and their correlation was investigated. RESULTS: HA significantly upregulated HER-2 and TGFß in MCF-7/CD44st cells, increased p-AKT expression and AP-1 activity, and promoted the invasive ability of tumor cells. CD44st mRNA expression had significant difference between breast cancer tissues and adjacent normal tissues (P < 0.05), and high expression of CD44st mRNA was closely correlated with HER-2 expression in breast cancer tissues. CONCLUSION: Binding of HA to the CD44st receptor may regulate the invasiveness of MCF-7 cells through the CD44st/TGFß/PI3K/AP-1 signaling pathway with increased expression of TGFß and HER-2. The expression of CD44st mRNA is correlated with HER-2 expression in postoperative breast cancer patients.

Expression of Novel CD44st and MMP2 in NSCLC Tissues and Their Clinical Significance.

BACKGROUND: Abnormal expression of some CD44 molecules in tumor tissues can induce the degradation of the extracellular matrix, and is closely associated with axillary lymph node metastasis, angiogenesis, cancer progression, and drug resistance. PATIENTS AND METHODS: We measured and confirmed the expression of CD44st and MMP2 mRNAs and proteins in the cancer tissues and adjacent normal tissues of postoperative non-small cell lung cancer (NSCLC) patients with either adenocarcinoma (n = 72) or squamous cell carcinoma (n = 53) using quantitative reverse transcription polymerase chain reaction, gene sequencing, and immunohistochemical analysis. RESULTS: CD44st and MMP2 expression were closely associated with the histopathological classification, lymph node metastasis, and TNM stage of the tumors, and the difference was statistically significant (p < 0.05). The median overall survival (OS) for the high CD44st expression group was 30.52 months (95% confidence interval (CI) 24.02-36.15); for the low expression group it was 43.23 months (95% CI 31.81-52.02) (p = 0.020). The median OS for the high MMP-2 expression group was 30.53 months (95% CI 26.69-33.31); for the low expression group it was 40.06 months (95% CI 33.55-46.45) (p = 0.022). CONCLUSION: The rates of CD44st and MMP2 expression were higher in squamous cell carcinomas than in adenocarcinomas, were closely associated with lymph node metastasis and TNM stage, and affected patients' prognoses.

Doxorubicin induces drug resistance and expression of the novel CD44st via NF-κB in human breast cancer MCF-7 cells.

CD44, a major receptor for hyaluronan (HA), is a member of a class of adhesion molecules of unknown classification involved in cell proliferation, differentiation, migration, angiogenesis, and the presentation of specific cytokines to the corresponding receptors as well as in cell signaling transduction. It has recently been discovered that CD44, a marker of tumor stem cells, is involved in the drug resistance and invasion of multiple types of tumors. The 20 exons in the CD44 gene that are alternatively spliced, give rise to many CD44 isoforms, possibly including tumor-specific sequences. Dozens of CD44 isoforms have been found, to date, and the standard CD44 (CD44s) isoform is the most common. We recently showed that a novel short-tail isoform of CD44 (CD44st) was expressed in multidrug-resistant human breast cancer MCF-7/Adr cells. Moreover, the novel CD44st was able to interact with HA and regulate the expression of matrix metalloproteinase (MMP)-2 and MMP-9, which increased the invasive capability of MCF-7 cells through the Ras/MAPK signaling pathway. In the present study, we verified that MCF-7 cells subjected to drug pressure develop multidrug resistance to doxorubicin, and the expression levels of multidrug resistance protein 1 (MDR1), CD44st and nuclear factor-κB (NF-κB) mRNA and protein were gradually upregulated in a dose­dependent manner in MCF-7 cells treated with doxorubicin. HA increases the secretion of MMP-2 and MMP-9 in multidrug-resistant MCF-7 cells and affected the invasive ability of MCF-7 cells through the upregulation of CD44st expression, and such an effect was blocked by the NF-κB-specific inhibitor BMS-345541.

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.

The role of a new CD44st in increasing the invasion capability of the human breast cancer cell line MCF-7.

BACKGROUND: CD44, a hyaluronan (HA) receptor, is a multistructural and multifunctional cell surface molecule involved in cell proliferation, cell differentiation, cell migration, angiogenesis, presentation of cytokines, chemokines and growth factors to the corresponding receptors, and docking of proteases at the cell membrane, as well as in signaling for cell survival. The CD44 gene contains 20 exons that are alternatively spliced, giving rise to many CD44 isoforms, perhaps including tumor-specific sequences. METHODS: Reverse transcriptase polymerase chain reaction (RT-PCR) and Western blotting were used to detect CD44st mRNA and CD44 protein in sensitive MCF-7, Lovo, K562 and HL-60 cell lines as well as their parental counterparts, respectively. The full length cDNA encoding CD44st was obtained from the total RNA isolated from MCF-7/Adr cells by RT-PCR, and subcloned into the pMD19-T vector. The CD44st gene sequence and open reading frame were confirmed by restriction enzyme analysis and nucleotide sequencing, and then inserted into the eukaryotic expression vector pcDNA3.1. The pcDNA3.1-CD44st was transfected into MCF-7 cells using Lipofectamine. After transfection, the positive clones were obtained by G418 screening. The changes of the MMP-2 and MMP-9 genes and protein levels were detected by RT-PCR and gelatin zymography, respectively. The number of the cells penetrating through the artificial matrix membrane in each group (MCF-7, MCF-7+HA, MCF-7/neo, MCF-7/neo+HA, MCF-7/CD44st, MCF-7/CD44st+HA and MCF-7/CD44st+Anti-CD44+HA) was counted to compare the change of the invasion capability regulated by the CD44st. Erk and P-Erk were investigated by Western blotting to approach the molecular mechanisms of MMP-2 and MMP-9 expression regulated by the CD44st. RESULTS: Sensitive MCF-7, Lovo, K562 and HL-60 cells did not contain CD44st mRNA and CD44 protein. In contrast, the multidrug resistance MCF-7/Adr, Lovo/Adr, K562/Adr and HL-60/Adr cells expressed CD44st mRNA and CD44 protein. The CD44st mRNA gene sequence was successfully cloned into the recombinant vector pcDNA3.1 and identified by the two restriction enzymes. It was confirmed that the reconstructed plasmid contained the gene sequence of CD44st that was composed of exons 1 to 4, 16 to 17, and 1 to 205 bases of exons 18. The new gene sequence was sent to NCBI for publication, and obtained the registration number FJ216964. The up-regulated level of the mRNA of the CD44 gene and the CD44 protein were detected, respectively, by RT-PCR and flow cytometry in MCF-7 cells transfected with pcDNA3.1-CD44st. The invasiveness of the cells and the activity of MMP-2 and MMP-9 were clearly activated by HA treatment, and blocked by CD44 neutralizing antibody. MCF-7/CD44st cells pretreated with the neutralizing antibody against CD44, and the inhibitor of MAPKs signaling pathway, could strongly block the expression of P-Erk. CONCLUSIONS: A new CD44st was expressed in multidrug resistant MCF-7/Adr, Lovo/Adr, K562/Adr and HL-60/Adr cells. The expression vector pcDNA3.1-CD44st was cloned and constructed successfully, and stably transfected into MCF-7 cells. HA could interact with the new CD44st and regulate the expression of MMP-2 and MMP-9, which could increase the invasion capability of MCF-7 cells through the Ras/MAPK signaling pathway.

[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.