Objective To investigate the influences of imatinib on Survivin gene expression in bcr-abl-transformed leukemia cells.Methods Firstly,PCR and Western blot were carried out to detected Survivin expression with imatinib treatment in 32Dcl3 and 32D-bcr-abl cell lines.Then the luciferase reporter plasmids containing human Survivin promoter as well as its deletion and site-directed mutation were constructed to identify the essential responsive elements for suppressing Survivin promoter activity by imatinib.Chromatin immunoprecipitation was performed to confirm the binding of c-myc to Survivin promoter.10058-F4,a small molecule c-myc inhibitor,was used to disrupt c-myc activity and evaluate its anti-leukemic effect combined with imatinib.Results Both of mRNA and protein level of Survivin in bcr-abl-transformed cells were downregulated upon imatinib treatment.The decrease of Survivin expression was controlled at the transcriptional level through a mechanism in which imatinib repressed survivin promoter activity by disturbing the interaction between c-myc and E-box elements.Interruption of c-myc activity by 10058-F4 exerted an anti-leukemia effect with enhancing the sensibility of K562/G01 cells to imatinib.Conclusion Imatinib down-regulates Survivin expression through c-myc-mediated transcription and interference with c-myc might be a potential utility for treatment of imatinib resistant leukemia.

Rectal cancer is one of the most common malignant tumors in China, and the proportion of elderly patients is also increasing. Due to the lack of prospective evidence-based medical research for elderly patients, no consensus on the optimal treatment model has been reached. In this article, relevant researches on the comprehensive treatment strategy of locally advanced rectal cancer in the elderly patients were reviewed, aiming to provide reference for individualized treatment of elderly patients.

Objective To identify clinical prevalence of untypical adefovir-resistant mutations of hepatitis B virus (HBV),and to analyze their phenotypic characteristics.Methods 1741 patients with chronic HBV infection were evolved.Untypical adefovir-resistant mutations were analyzed by direct sequencing.Longitudinal analysis was performed by clonal sequencing.Wild-type and mutant HBV genomic amplicons were constructed into pTriEx-HBV 1.1 vector and transfected into HepG2 cells.The replication capacity and the 50％ effective concentration of drugs (EC50) were calculated.Results Patients treated with adefovir alone were more likely to develop rtN238T mutation than those treated with other nucleos(t) ide drugs (x2 =17.10,P ＜ 0.01).The patient received adefovir for 47 months,and then viral rebound and biochemical breakthrough occurred with detection of rtN238T + A181V and rtN238T mutation.Switching-to entecavir therapy suppressed HBV DNA and ALT to an undetectable level and converted all viruses into wild type ones.The reulsts of viral replication capacity showed that rtN238T + A181V strain was higher than rtA181V strain (t =9.54,P ＜ 0.01).Compared to the wild type virus,rtN238T + A181V variant was relatively less susceptible to adefovir.Conclusions rtN238T mutation conferred no resistance to ADV but enhanced natural replication capacity,hence it might represent a novel compensatory drug-resistant mutation for adefovir.

OBJECTIVETo determine the mutational profile and clinical implications of the viral reverse-transcriptase (rt)A 181T mutation in hepatitis B virus (HBV) through population-based analysis of clinical samples.

METHODSSerum samples from 3, 013 patients who visited The 302 Hospital (Beijing, China) were investigated.HBV DNA was extracted and HBV mutations and genotypes were determined by direct sequencing.Recombinant plasmids harboring the rtA181T/sW172* mutant or wild type sequence were constructed and transfected into the HepG2 cell line. The levels of HBsAg in culture supernatants were compared and statistically analyzed.

RESULTSThe incidence of rtA181T across the study population was 4.1% (165/3, 013), and most of the rtAl 81T-positive patients had received adefovir and/or lamivudine.Forty percent (66/165) of the rtA 181T cases were single mutants and treatment responsive, 46.1% (76/165) included the adefovir-resistant mutation rtA 181 V/N236T, 12.1% (20/165) included the lamivudine-resistant mutation rtM204V/rtM2041, and 1.8% (3/165) included multidrug-resistant mutations.Interestingly, 73.9% (122/165) of the rtA181T-positive samples were detected with co-existing wild-type nucleotides at the site. The rates of HBV/C to HBV/B were 92.1% to 7.9% in the rtA181T-positive patients, but 82.1% to 17.9% in the rtA181T-negative paticnts (P less than 0.01).Almost all (98.2%; 129/165) of the rtA181T led to sW172*, while only 1.8% of the rtA181T (3/165) led to sW172L or sW172S.HBsAg secretion in vitro was reduced from the rtA181T/ sW172* strain, but there was no significant difference observed in the average serum HBsAg and HBV DNA levels of patients who carried or did not carry the mutant.

CONCLUSIONThe HBV rtA181T mutation is closely associated with adefovir and lamivudine exposure.rtA181T may led to sW172*, culminating in suppression of HBsAg secretion.However, co-existence of the mutant with wild-type sequences was common among our patient population, suggesting that the mutation had little impact on serum HBsAg and HBV DNA levels across the clinical study population.

Adenine ; analogs & derivatives ; Antiviral Agents ; China ; Genotype ; Hepatitis B Surface Antigens ; Hepatitis B virus ; Humans ; Lamivudine ; Mutation ; Organophosphonates