Circular RNA circ-ERBB2 promotes HER2-positive breast cancer progression and metastasis via sponging miR-136-5p and miR-198.

BACKGROUND: Circular RNAs (circRNAs) are pivotal regulators of various human cancers and circ-ERBB2 is abnormally expressed in breast cancer cells. However, the role and mechanism of circ-ERBB2 in HER2-positive breast cancer are still unknown. METHODS: The circ-ERBB2 expressions in the tumor tissues of HER2-positive breast cancer patients were tested using quantitative real-time PCR. The circ-ERBB2 function was investigated by cell counting kit 8 assay, Transwell, flow cytometry and Western blot. Mechanistically, fluorescence in situ hybridization, RNA immunoprecipitation, RNA pull-down and dual-luciferase reporter gene assays were conducted to confirm the interaction between circ-ERBB2 and miR-136-5p or miR-198 in HER2-positive breast cancer cells. RESULTS: Circ-ERBB2 was elevated in the tumor tissues of HER2-positive breast cancer patients. Functionally, the interference with circ-ERBB2 repressed HER2-positive breast cancer cell proliferation, migration, invasion and accelerated cell apoptosis. Furthermore, the mechanistic analysis corroborated that circ-ERBB2 acted as a competing endogenous RNA for miR-136-5p or miR-198 to relieve the repressive influence of miR-136-5p or miR-198 on its target transcription factor activator protein 2C (TFAP2C). Meanwhile, in vivo assays further corroborated the oncogenic function of circ-ERBB2 in HER2-positive breast cancer. CONCLUSIONS: Circ-ERBB2 accelerated HER2-positive breast cancer progression through the circ-ERBB2/miR-136-5p/TFAP2C axis or the circ-ERBB2/miR-198/TFAP2C axis.

[Expression of CSN Complex in ATRA-induced APL Cell Differentiation and Its Clinical Significance].

OBJECTIVE: To investigate the expression of CSN complex (COP9 signal some subunits) in the patients with acute promyelocytic leukemia (APL) and its significance in the ATRA-induced APL differentiation. METHODS: Using the NB4 cells as a model, morphologic observation and myeloid differentiation marker CD11b detection were used to monitor ATRA-induced APL differentiation, the expression of CSN complex in cell differentiation was detected by Western blot and reverse transcription real time fluorescent quantitative PCR (RT-qPCR) method. RT-qPCR was also used to detect the relative expression level of COP9 signalosome subunits in the APL patients and remission after treatment. RESULTS: ATRA could obviously enhance CD11b expression; the cell morphology showed obvious differentiation characteristics. During the differentiation, the expression of COP9 signalosome subunits was down-regulated by ATRA. Meanwhile, the CSN expression level in newly diagnosed APL patients was much higher than that in controls (non-leukemia) (P < 0.05). The level of CSN expression was obviously down-regulated when APL patients achieved complete remission. CONCLUSION: The high CSN expression level in APL patients can be down-regulated by ATRA. CSN complex may have a significant effect on the pathogenesis and therapy of APL.

[Early monitoring drug-resistance of patients with BCR/ABL(+) ALL by DCDF-FISH].

This study was aimed to investigate the application value of the dual color dual fusion fluorescence in situ hybridization (DCDF-FISH) in BCR/ABL (+) acute lymphoblastic leukemia patients with complex chromosomal translocation. The clinical presentations of a patient with ALL were monitored regularly by bone marrow cell morphology test, chromosome analysis, flow cytometry and DCDF-FISH technique, and the reaction of patients to treatment and disease progression were dynamically observed by DCDF-FISH. The results indicated that the patient showed the typical presentation of B lineage acute lymphoblastic leukemia (B-ALL) with expression of CD10, CD19 and CD34; the chromosome analysis showed 46,XY, i(8), ider(9)t (9; 22) [23]/47, idem, +der(22) t (9;22) [7] karyotype in the bone marrow cells, FISH showed that 83% cells contained BCR/ABL fusion gene in the patient's bone marrow, among which 5% cells showed 1R1G2F signalling model, 14% cells showed 1R1G3F, and 64% cells showed 1R1G4F. The patient got complete remission when the imatinib chemotherapy combined with VTLP was carried out, and the tumor cells decreased to 19%, but the cells with 1R1G2F signal model increased to 18%. The 1R1G2F cell signal model increased up to 38% when patient relapsed. The patient died of the drug-resistance. It is concluded that the BCR/ABL (+) leukemia patient with complex translocation has multiple tumor cell subsets, and the responses of different cell subsets to the treatment are different, therefore the response to therapy and drug resistance of patient can be monitored early by the signal model of DCDF-FISH and the observation of dynamical changes of different cell subset.

[Effect of curcumin combined with ATRA on differentiation of ATRA-resistant acute promyelocytic leukemia cells].

In order to investigate the effect of curcumin combined with all-trans retinoid acid (ATRA) on differentiation of ATRA-resistant acute promyelocytic leukemia (APL) cells and its molecular mechanism, the NB4-R1, an ATRA-resistant APL cells, was used as a model, counting of NB4-R1 and cell morphologic observation were performed, the effect of curcumin alone or combined with ATRA on proliferation, differentiation of NB4-R1 cells was detected by flow cytometry (FCM), the change of AKT phosphorylation in cell differentiation was detected by Western blot. The results showed that ATRA had no influence on NB4-R1 cell proliferation, but enhanced the inhibitory effect of curcumin on NB4-R1 cell growth; the curcumin or ATRA alone did not affect NB4-R1 differentiation; curcumin combined with ATRA could obviously induce CD11b expression; the cell morphology showed obvious differentiation characteristics. ATRA could promote phosphorylation of AKT in NB4 cells at short time, but not had effect on phosphorylation of AKT in NB4-R1 cells; the curcumin could enhance the phosphorylation of AKT in NB4-1R cells, the curcumin combined with ATRA could further enhance the phosphorylation of AKT. It is concluded that PI3K/AKT pathway inactivation may be one of the factors of drug resistance in APL and curcumin promotes differentiation of NB4-R1 through activating PI3K/AKT pathway.

[Apoptosis of retinoic acid resistant NB4-R1 cells induced with curcumin and its mechanism].

This study was purposed to explore the inhibitory effect of Curcumin on growth of retinoic acid-resistant acute promyelocytic leukemia (APL) cells and its mechanism. The NB4-R1, an APL cell line resistant to retinoic acid, was used as a model. The growth level of NB4-R1 was detected by MTT assay, the morphologic features of cells were observed by light microscopy, the mitochondrial transmembrane potential was determined by flow cytometry, the expressions of apoptosis-related proteins procaspase 3, caspase 3, PARP and BCL-XL were measured by Western blot. The results indicated that the sensitivity of NB4-R1 to Curcumin was consistent with NB4 though NB4-R1 was resistant to retinoic acid, Curcumin displayed inhibitory effect on growth of NB4-R1 in time-and concentration-dependent manners. The morphologic observation showed existence of apoptotic bodies in NB4-R1 cells treated with 20 micromol/L of Curcumin. The flow cytometry indicated that the mitochondrial transmembrane potential in NB4-R1 cells treated with 20 micromol/L of Curcumin obviously decreased. The Western blot detection revealed that expressions of pro-caspase 3 and BCL-XL were down-regulated, expressions of caspase 3 and sheared PAPP were up-regulated in NB4-R1 cells treated with 20 micromol/L of Curcumin. It is concluded that the Curcumin can inhibit the growth and induce the apoptosis of NB4-R1.