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Multidrug resistance (MDR) is a challenge for the treatment of cancer and the underlying molecular mechanisms remain elusive. The current study exposed MG63 osteosarcoma cells to increasing concentrations of vincristine (VCR) to establish four VCR-resistant MG63/VCR cell sublines (MG63/VCR1, 2, 3 and 4). The drug resistance indices (RI) of these sublines was detected with the CCK-8 assay and determined to be163, 476, 1,247, and 2,707-fold higher than that of parental cells, respectively. These sublines also exhibited cross-resistance to doxorubicin, paclitaxel and pirarubicin. With increased RI, the proliferative capacity of these sublines was gradually reduced and cell morphology was also altered, characterized by increased formation of pseudopodia and long cytoplasmic processes at opposite poles. However, the migration capacity and expression of certain drug resistance-associated genes were not in accordance with the increased RI; multidrug resistance protein 1 (MDR1) expression was significantly increased in these sublines compared with parental cells. However, in the highly resistant MG63/VCR3 and MG63/VCR4 cells, MDR-associated protein 1, topoisomerase II and LIM domain kinase 1 levels were significantly reduced compared with the moderately resistant MG63/VCR2 cells. Expression of glutathione S-transferase-⨅ mRNA was determined using reverse transcription-quantitative polymerase chain reaction and determined that it was not changed between MG63 and MG63/VCR cells. The data of the present study demonstrated that the molecular alterations of drug resistance may change with the degree of drug resistance. Taking cell morphology into consideration, the intratumor clonal and phenotypic heterogeneity may be responsible for drug resistance. These MG63/VCR sublines may be a valuable tool to assess drug resistance and the underlying mechanisms, and to identify novel drug resistance-associated genes or strategies to overcome MDR in human osteosarcoma. [ABSTRACT FROM AUTHOR]

Evodiamine (Evo) is an alkaloid that can be extracted from the berry fruit Evodia rutaecarpa and has been reported to exert various pharmacological effects, such as antidiarrheal, antiemetic and antiulcer effects. In vivo, the potential effects of Evo were investigated in a mouse model of dextran sodium sulfate (DSS)-induced ulcerative colitis (UC) and in adenomatous polyposis coli (Apc)MinC/Gpt C57BL/6 mice with colorectal cancer (CRC), where the latter harbours a point-mutation in the Apc gene. Evo suppressed the degree of weight loss and colon shortening induced by DSS, decreased the disease activity index value and ameliorated the pathological alterations in the colon of mice with UC as examined via H&E staining of colon tissues. In addition, Evo decreased the number and size of colonic tumors in ApcMinC/Gpt mice. Proteomics (colon tissues), ELISA (colon tissues and serum) and western blotting (colon tissues) results revealed that Evo inhibited NF-κB to mediate the levels of various cytokines, including, in the DSS-induced UC model, IL-1β, IL-2, IL-6, IL-8, TNF-α, IFN-γ (ELISA of colon tissues and serum), NF-κB, IKKα+β, IκBα, S100a9, TLR4 and MyD88 (western blotting of colon tissues), and, in the colorectal cancer model, IL-1β, IL-2, IL-6, IL-15, IL-17, IL-22, TNF-α (ELISA of colon tissues and serum), NF-κB, IKKα+β, IκBα and S100a9 (western blotting of colon tissues), to achieve its anti-inflammatory and antitumor effects. In vitro, Evo also reduced the viability of the colon cancer cell line SW480, inhibited mitochondrial membrane potential (MMP detection), caused G2/M-phase arrest (cell cycle detection) and suppressed the translocation of phosphorylated-NF-κB from the cytoplasm into the nucleus (immunofluorescence of p-NF-κB). Theoretical evidence (MD simulations) suggest that Evo may bind to the ordered domain (α-helix) of NF-κB to influence this protein. The protein secondary structure changes were analyzed by the cpptraj module in Amber. In addition, these data provide experimental evidence that Evo may be an effective agent for treating UC and CRC. [ABSTRACT FROM AUTHOR]

Osteosarcoma is a type of malignant bone tumor with high metastasis and poor prognosis. Previous studies have demonstrated the involvement of LIM kinase 1 (LIMK1) in the proliferation of osteosarcoma cells. LIMK1 is over expressed in human osteosarcoma tissues and cell lines. To further study LIMK1-associated mechanisms, we used shRNA targeted to the LIMK1 gene to block its expression in the osteosarcoma cell lines MG63 and U2OS. Insulin promoted the proliferation of MG63 cells in a time- and dose-dependent manner, however, this insulin induced proliferation was significantly inhibited by transfection of shRNA targeted to the LIMK1 gene, as well as by the PI3K inhibitor LY294002, but not by the mitogen-activated protein kinase (MAPK) inhibitor PD98059. The level of cofilin phosphorylation was increased significantly following stimulation of insulin for 24 h, indicating the activation of LIMK1. MG63 cell proliferation was also significantly inhibited by 1,25-dihydroxy vitamin D3 (1,25(OH)2D3) in a time-dependent manner. Furthermore, 1,25(OH)2D3 negated the inhibitory effect of LIMK1 shRNA, indicating that LIMK1 is important in the inhibitory pathway of 1,25(OH)2D3. The present study confirms that LIMK1 is important in regulating osteosarcoma cell proliferation via the insulin/PI3K/LIMK1 signaling pathway, thus the development of gene therapy for osteosarcoma targeting LIMK1 is warranted. [ABSTRACT FROM AUTHOR]