Resistance to bortezomib (BZ) is the major problem that largely limits its clinical application in multiple myeloma treatment. In the current study, we investigated whether ClC5, a member of the chloride channel family, is involved in this process. The MTT assay showed that BZ treatment decreased cell viability in three multiple myeloma cell lines (ARH77, U266, and SKO-007), with IC values of 2.83, 4.37, and 1.91 nM, respectively. Moreover, BZ increased the conversion of LC3B-I to LC3B-II and expressions of beclin-1 and ATG5, concomitantly with a decreased p62 expression. Pharmacological inhibition of autophagy with 3-MA facilitated cell death in response to BZ treatment. Additionally, BZ increased ClC5 protein expression in ARH77, U266, and SKO-007 cells. Knockdown of ClC5 with small interfering RNA sensitized cells to BZ treatment, and upregulation of ClC5 induced chemoresistance to BZ. Furthermore, ClC5 downregulation promoted BZ-induced LC3B-I to LC3B-II conversion and beclin-1 expression, whereas overexpression of ClC5 showed the opposite results in ARH77 cells. Finally, BZ induced dephosphorylation of AKT and mTOR, which was significantly attenuated by ClC5 inhibition. However, ClC5 upregulation further enhanced AKT and mTOR dephosphorylation induced by BZ. Our study demonstrates that ClC5 induces chemoresistance of multiple myeloma cells to BZ via increasing prosurvival autophagy by inhibiting the AKT-mTOR pathway. These data suggest that ClC5 may play a critical role in future multiple myeloma treatment strategies.

Acute myelogenous leukemia (AML) is frequently accompanied by a poor prognosis. The majority of patients with AML will experience recurrence due to multiple drug resistance. Our previous study reported that targeting the mTOR pathway may increase cell sensitivity to doxorubicin (Doxo) and provide an improved therapeutic approach to leukemia. However, the effect and mechanism of action of NVP-BEZ235 (BEZ235), a dual inhibitor of PI3K/mTOR, on Doxo-resistant K562 cells (K562/A) is yet to be elucidated. Therefore, the aim of the present study was to investigate the effects of BEZ235 on K562/A cell proliferation. K562/A cells was investigated using CCK-8, flow cytometry and western blotting, following BEZ235 treatment. It was observed that BEZ235 significantly decreased the viability of K562/A cells. In addition, BEZ235 arrested K562/A cells at the G 0 /G 1 phase, and reduced the protein expression levels of CDK4, CDK6 and cyclin D1. Apoptotic cells were more frequently detected in K562/A cells treated with BEZ235 compared with the control group (12.97±0.91% vs. 7.37±0.42%, respectively; P<0.05). Cells treated with BEZ235 exhibited downregulation of Bcl-2 and upregulation of Bax. Furthermore, BEZ235 treatment markedly decreased the activation of the PI3K/AKT/mTOR pathway and its downstream effectors. Thus, these results demonstrated that BEZ235 inhibited cell viability, induced G 0 /G 1 arrest and increased apoptosis in K562/A cells, suggesting that BEZ235 may reverse Doxo resistance in leukemia cells. Therefore, targeting the PI3K/mTOR pathway may be of value as a novel therapeutic approach to leukemia.

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Objective To evaluate the clinical efficacy and safety of allogenic dendritic cells (DCs) and cytokine-induced killer (CIK) cells in the eliminating minimal residual leukemia (MRL). Methods 48 acute leukemia patients with hematological complete remission (CR) but without molecular biological remission (CRM), or patients with minimal residual Leukemia (MRL) were selected from Ping’an Hospital of Shijiazhuang during Jan. 2009 to Jun. 2011. According to the patients’ will, 48 patients divided into combined treatment group and chemotherapy group 24 each. All the patients were in the same general information and disease level. The combined treatment group was treated with DC-CIK and consolidation chemotherapy, and the chemotherapy group was treated with consolidation chemotherapy. PBMCs were collected from healthy donors (the patient's parents or children) to prepare DC-CIK cells. DC-CIK cells were intravenous injected into patients once every 15 days, a total of 4-6 times infusion. The blood routine, bone marrow cells, leukemia related genes, urine and stool routine, liver and kidney biochemistry function, and ECG were observed. Changes of peripheral lymphocyte subsets in patients were detected by flow cytometry. Adverse reactions were examined. Results (1)Eleven cases in the combined treatment group achieved CRM, and the CRM rate was 45.8%; whereas only 2 cases in the chemotherapy group achieved CRM and the CRM rate was 8.3%,the difference was statistically significant(χ2=8.55, P<0.01).(2) Compared with the chemotherapy group, the CFIM (four-color combination flow cytometric immunophenotype of minimal residual leukemia) negative conversion rate of patients in the combined treatment group was significantly raised (66.7% vs 25.0%,χ2=8.39, P<0.01). (3)The negative conversion rate of MRL was higher in the combined treatment group than the chemotherapy group (66.7% vs25.0%, χ2=8.39, P<0.01). (4) After treatment the ratio of CD4+/CD8+ cells was significant increased than before treatment in the combined treatment group (1.3±0.4 vs 0.8±0.4, P<0.05). (5)The complete remission rate (CCR) of patients in the combined treatment group after 3 years was 79.2%, while that in the chemotherapy group was 45.8% (χ2=5.69, P<0.05).(6)No dysfunction of critical organs such as heart, liver and kidney and serious adverse reactions were observed while DC-CIK cells infusion. Conclusion DC-CIK combined with chemotherapy can inhibit leukemia gene, promote the negative conversion rate of CFIM, facilitate the clear of MRL, improve immune function and prolong remission of the patients.No serious adverse reactions were found in patients with DC-CIK infusion. Disclosures: No relevant conflicts of interest to declare.