Circular RNA circPSAP functions as an efficient miR-331-3p sponge to regulate proliferation, apoptosis and bortezomib sensitivity of human multiple myeloma cells by upregulating HDAC4.

BACKGROUND: Multiple myeloma (MM) is a malignant tumor of plasma cells in the bone marrow. Circular RNAs (circRNAs) exert important activity in the tumorigenesis and chemoresistance of MM. In the current work, we sought to identify the expression, activity, and mechanism of circPSAP activity in MM. METHODS: CircPSAP, microRNA (miR)-331-3p, and histone deacetylase 4 (HDAC4) were quantified by qRT-PCR and immunoblotting assays. Cell proliferation and survival were assessed by CCK-8 assay. Cell cycle and apoptosis were detected by flow cytometry. The direct relationship between miR-331-3p and circPSAP or HDAC4 3'UTR was validated by dual-luciferase reporter, RNA pull-down, and RNA immunoprecipitation (RIP) assays. RESULTS: CircPSAP was overexpressed in human MM and high levels of circPSAP predicted poor prognosis in MM patients. CircPSAP depletion repressed cell proliferation and promoted apoptosis and BTZ sensitivity. Mechanistically, circPSAP functioned as a miR-331-3p sponge, and circPSAP regulated cell proliferation, apoptosis and BTZ sensitivity by sponging miR-331-3p. MiR-331-3p directly targeted and inhibited HDAC4. MiR-331-3p-mediated inhibition of HDAC4 impaired cell proliferation and enhanced cell apoptosis and BTZ sensitivity. Moreover, circPSAP modulated HDAC4 expression by acting as a miR-331-3p sponge. CONCLUSION: Our findings highlight a novel mechanism, in which circPSAP functions as a miR-331-3p sponge to impact MM cell proliferation, apoptosis and BTZ sensitivity by regulating HDAC4 expression.

ALKBH5-mediated m6A-demethylation of USP1 regulated T-cell acute lymphoblastic leukemia cell glucocorticoid resistance by Aurora B.

Recent studies evidence that ubiquitin-specific proteases (USPs) are associated with the occurrence and chemoresistance of T-cell acute lymphoblastic leukemia (T-ALL). N6 -methyladenosine (m6A) demethylase AlkB homolog 5 (ALKBH5) exerts a carcinogenic effect in human cancers and improves the mRNA stability of USPs. Whether ubiquitin-specific protease 1 (USP1) controls chemoresistance of T-ALL is unknown. Our study demonstrated that USP1 expression was upregulated in glucocorticoid (GC)-resistant T-ALL patients and cells (CEM-C1). High expression of USP1 was correlated to the poor prognosis in T-ALL patients. Silencing USP1 increased CEM-C1 cell sensitivity to dexamethasone (Dex), reduced cell invasion, promoted cell apoptosis, and ameliorated glucocorticoid receptor (GR) expression. USP1 mediated T-ALL chemoresistance by interacting with and deubiquitination of Aurora B. Overexpression of USP1 reversed the amelioration effect of Aurora B inhibitor on CEM-C1 cell resistance to Dex. Mechanistically, ALKBH5 enhanced USP1 expression by reducing m6A level and mRNA stability in USP1 mRNA transcript. Downregulation of ALKBH5 reduced the levels of USP1 and Aurora B, facilitated CEM-C1 cell sensitivity to Dex, apoptosis, and GR expression, suppressed cell invasion. However, overexpression of USP1 reversed all the effects of ALKBH5 on CEM-C1 cells. In vivo results showed that tail vein injection of sh-USP1 resulted in a significant prolongation of mouse survival, suppressed tumor growth, maintained the normal weight of mice, reduced USP1 expression and facilitated GR expression. In conclusion, inhibition of ALKBH5-mediated m6A modification decreased USP1 expression and downregulation of USP1 ameliorated GC resistance of T-ALL through suppressing Aurora B expression and elevating GR level.

m6A methyltransferase Wilms' tumor 1-associated protein facilitates cell proliferation and cisplatin resistance in NK/T cell lymphoma by regulating dual-specificity phosphatases 6 expression via m6A RNA methylation.

Nasal-type natural killer/T-cell lymphoma (NKTCL) is an aggressive malignancy with poor survival outcomes that is relatively resistant to chemotherapy. N6-Methyladenosine (m6A) modification, the most prevalent modification of eukaryotic messenger RNA, is involved in the progression of various tumors. However, it is unclear whether it has a physiological role in NKTCL development. To address this question, we probed its function and molecular mechanisms in NKTCL. Initially, we demonstrated that Wilms' tumor 1-associated protein (WTAP), a major RNA N6-adenosine methyltransferase, was obviously upregulated in human NKTCL cell lines (YTS and SNK-6 cells), compared with normal NK cells. Functionally, depletion of WTAP noticeably repressed proliferation and facilitated apoptosis in YTS and SNK-6 cells. Moreover, intervention of WTAP evidently prohibited NKTCL cell chemotherapy resistance to cisplatin, as reflected by a lower inhibition of cell viability and decreased expression of drug resistance-associated protein expression MRP-1 and P-gp in YTS and SNK-6 cells. With regard to the mechanism, we revealed that WTAP enhanced dual-specificity phosphatases 6 (DUSP6) expression by increasing m6A levels of DUSP6 mRNA transcript, leading to oncogenic functions in NKTCL. Interestingly, WTAP contributed to the progression and chemotherapy sensitivity of NKTCL by stabilizing DUSP6 mRNA in an m6A-dependent manner. Taken together, these findings uncovered a critical function for WTAP-guided m6A methylation and identified DUSP6 as an important target of m6A modification in the regulation of chemotherapy resistance in NKTCL oncogenesis. This study highlights WTAP as a potential therapeutic target of NKTCL treatment.

Association of polymorphisms of CYP11B2 gene -344C/T and ACE gene I/D with antihypertensive response to angiotensin receptor blockers in Chinese with hypertension.

The aim of this study was to determine whether the polymorphism of aldosterone synthase (CYP11B2) -344C/T and angiotensin-converting enzyme (ACE) insertion/deletion (I/D) were associated with the response of blood pressure (BP) to telmisartan treatment. After a two-week single-blind placebo run-in period, 148 patients with mild-to-moderate primary hypertension received monotherapy of telmisartan with 80 mg/day and then were followed up for eight weeks. Polymorphisms of CYP11B2 -344C/T and ACE I/D gene were determined through polymerase chain reaction-restriction fragment polymorphism analysis. The relationship between these polymorphisms and changes in BP was monitored and evaluated after eight weeks of treatment. With respect tothe polymorphism of CYP11B2 -344C/T, the reduction in diastolic BP was significantly greater in patients carrying the C allele (CC+CT) compared with those carrying the TT genotype. There was no significant differences between ACE I/D polymorphism and BP reduction after treatment. We concluded that the aldosterone synthase -344C/T polymorphism was related to the antihypertensive treatment with telmisartan in hypertensive patients.

Association of mononucleotide polymorphisms of angiotensinogen gene at promoter region with antihypertensive response to angiotensin receptor blockers in hypertensive Chinese.

INTRODUCTION:: This study aimed to investigate whether mononucleotide polymorphisms of the angiotensinogen gene at promoter were associated with the blood-pressure-lowering response to telmisartan treatment. MATERIALS AND METHODS:: After a two-week single-blind placebo run-in period, 148 patients with mild-to-moderate primary hypertension received monotherapy with 80 mg/day of telmisartan and then were followed up for eight weeks. The -6A/G and -20A/C polymorphisms of the angiotensinogen gene at promoter were determined through polymerase chain reaction and restriction fragment length polymorphsim analysis. The relationship between these polymorphisms and changes in blood pressure was observed and evaluated after eight weeks of treatment. RESULTS:: There were no significant differences between -6A/G, -20A/C polymorphisms of the angiotensinogen gene and blood pressure reductions after treatment, p>0.05. CONCLUSION:: It is suggested that angiotensinogen-6 A/G and angiotensinogen-20 A/C polymorphisms were not associated with the antihypertensive response to telmisartan treatment in Chinese patients with hypertension.

[Absence of response to rituximab in patients with refractory primary immune thrombocytopenia].

OBJECTIVE: To explore the possible causes for an absence of response to rituximab (RTX) in patients with refractory immune thrombocytopenia (ITP). METHODS: A total of 20 refractory ITP patients on RTX therapy and 10 health volunteers were recruited from 2008 to 2013. Memory T lymphocytes (Tm) (CD4(+)CD45RO(+)) and B lymphocytes (CD19(+)CD20(+)) in peripheral blood (PB) were examined by flow cytometry (FCM). And enzyme-linked immunosorbent assay (ELISA) was employed for detecting the platelet-associated antibodies IgG/IgM (PAIgG/IgM). RESULTS: (1) 12 patients with refractory ITP achieved a good response after therapy with RTX (effective RTX group) and 8 cases failed to respond (ineffective RTX group). The PB levels of CD4(+)CD45RO(+)Tm were 41.33% ± 9.62% and 45.36% ± 8.57% respectively at pre-therapy and post-therapy in ineffective RTX group. And significant differences existed between ineffective and effective RTX groups (22.36% ± 11.57%, 26.65% ± 6.32%) versus health volunteers (19.72% ± 7.35%, 20.64% ± 7.35%) (all P < 0.05) . No statistical differences existed in the PB level of CD4(+)CD45RO(+)Tm between pre-therapy and post-therapy in ineffective or effective RTX group (both P > 0.05); (2) The PB level of CD19(+)CD20(+)B lymphocytes in RTX ineffective group was lower than that at pre-therapy in RTX effective group (16.36% (6.17%-27.53%) vs 45.72% (35.80%-57.19%), P < 0.05) . No significant difference existed in the level of CD19(+)CD20(+)B at post-therapy between ineffective and effective RTX groups (6.67% (4.09%-19.17%) vs 5.19% (3.78%-17.39%), P > 0.05). And significant differences existed in the PB level of CD19(+)CD20(+)B between pre-therapy and post-therapy in ineffective or effective RTX group (both P > 0.05); (3) PAIgG/IgM was not detected in RTX ineffective group. And PAIgG/IgM was found in 11 cases at pre-therapy versus 1 case at post-therapy in RTX effective group. CONCLUSION: CD4(+)CD45RO(+)Tm is probably associated with an absence of response to RTX in patients with refractory ITP.

[Influence of gemcitabine on expression of C-myc gene and its apoptosis-inducing effect on HL-60 cells].

The aim of this study was to investigate the effects of gemcitabine(GEM) on apoptosis and c-myc gene expression of HL-60 cells, and feasibility of using GEM in therapy of leukemia. The HL-60 cells were cultured in vitro. The expressions of the c-myc mRNA and C-MYC protein were detected by RT-PCR and Western-blot respectively. The cell apoptosis was analyzed by TUNEL staining. The results showed that after the HL-60 cells were treated with 1.0 microg/ml GEM for 12, 24, 36 and 48 hours, the expression of c-myc mRNA was inhibited to various degree. This inhibitory effect displayed time-dependent manner and the most optimal effective time was 24 hours. Compared GEM group with Ara-C group and blank control group, there were statistical differences (p<0.05). After the HL-60 cells were treated with 1.0 microg/ml GEM for 24, 48, 72 hours, C-MYC protein significantly decreased, and the expression of C-MYC protein reached to lowest level at 48 hours after treating with GEM, and with inhibition rate of 94.16%. Compared GEM group with Ara-C group and blank control group, the differences were significant (p<0.01). There was significant difference between cells treated with GEM for 24, 48 and 72 hours (p<0.01). After the HL-60 cells were treated with 1.0 microg/ml GEM for 24 hours, the apoptotic cells increased obviously. The positive rate was 83.67% in GEM-treated group. Compared GEM group with Ara-C group (positive rate 10.67%) and untreated group (positive rate 3.00%), the differences had statistical significance (p<0.01). It is concluded that GEM can induce the apoptosis and down-regulate c-myc gene expression significantly in HL-60 cells and it may be used as a new therapeutic drug for leukemia.

Synthesis, purification and opening of short cup-stacked carbon nanotubes.

A simple method is demonstrated to synthesize high-quality cup-stacked carbon nanotubes (CSCNTs) with short length. The as-synthesized CSCNTs are 0.2-3.2 microm in length, even shorter than the ball-milled long CSCNTs (approximately 7 microm). These CSCNTs have a diameter of 80-120 nm and a hollow channel of 60-100 nm along the nanotube axis. Moreover, a simple purification method is developed to remove iron particles and obtain short CSCNTs with two open ends. Such CSCNTs are very easily suspended in distilled water and tetrahydrofuran, which makes such material greatly promising as a candidate in many applications such as heterogeneous catalysis and photoelectrochemical cell.