Numerous studies confirmed that aberrant miRNAs expression contributes to multiple myeloma (MM) development and progression. However, the roles of specific miRNAs in MM remain to be investigated. In present study, we demonstrated that miR-410 expression was increased in MM newly diagnosed and relapsed tissues and cell lines. Clinical analysis revealed that miR-410 was positively correlated with advanced ISS stage. Moreover, high miR-410 expression in MM patients showed an obvious shorter overall survival and progression-free survival. Gain- and loss-of function experiments indicated that miR-410 promoted cell proliferation, cell cycle progression and apoptosis inhibition both in vitro and in vivo. Moreover, KLF10 was identified as a direct downstream target of miR-410 in MM cells, and mediated the functional influence of miR-410 in MM, resulting in PTEN/AKT activation. In clinical samples of MM, miR-410 inversely correlated with KLF10. Alteration of KLF10 expression or AKT inhibitor at least partially abolished the biological effects of miR-410 on MM cells. Furthermore, downregulated expression of lncRNA OIP5-AS1 was inversely correlated with miR-410 expression in MM tissues. LncRNA OIP5-AS1 could modulate the miR-410 expression and regulate its target KLF10/PTEN/AKT-mediated cellular behaviors. Taken together, this research supports the first evidence that lncRNA OIP5-AS1 loss-induced miR-410 accumulation facilitates cell proliferation, cycle progression and apoptosis inhibition by targeting KLF10 via activating PTEN/PI3K/AKT pathway in MM.

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Bryostatin 1 has attracted considerable attention both as a cancer chemotherapeutic agent and for its unique activity. Although it functions, like phorbol esters, as a potent protein kinase C (PKC) activator, it paradoxically antagonizes many phorbol ester responses in cells. Because of its complex structure, little is known of its structure-function relations. Merle 23 is a synthetic derivative, differing from bryostatin 1 at only four positions. However, in U-937 human leukemia cells, Merle 23 behaves like a phorbol ester and not like bryostatin 1. Here, we characterize the behavior of Merle 23 in the human prostate cancer cell line LNCaP. In this system, bryostatin 1 and phorbol ester have contrasting activities, with the phorbol ester but not bryostatin 1 blocking cell proliferation or tumor necrosis factor alpha secretion, among other responses. We show that Merle 23 displays a highly complex pattern of activity in this system. Depending on the specific biological response or mechanistic change, it was bryostatin-like, phorbol ester-like, intermediate in its behavior, or more effective than either. The pattern of response, moreover, varied depending on the conditions. We conclude that the newly emerging bryostatin derivatives such as Merle 23 provide powerful tools to dissect subsets of bryostatin mechanism and response.

Members of the erbB family receptor tyrosine kinases (erbB1, erbB2, erbB3, and erbB4) are overexpressed in a variety of human cancers and represent important targets for the structure-based drug design. Homo-and heterodimerization (oligomerization) of the erbB receptors are known to be critical events for receptor signaling. To block receptor self-associations, we have designed a series of peptides derived from potential dimerization surfaces in the extracellular subdomain IV of the erbB receptors (erbB peptides). In surface plasmon resonance (BIAcore) studies, the designed peptides have been shown to selectively bind to the erbB receptor ectodomains and isolated subdomain IV of erbB2 with submicromolar affinities and to inhibit heregulin-in- erbB2 (neu, HER2) is a member of the epidermal growth factor or HER family of tyrosine kinase receptors that also includes erbB1 (EGFR, 1 HER1), erbB3 (HER3), and erbB4 (HER4) (1-4). Overexpression of erbB receptors has been found in many types of human cancer raising the possibility that receptor-directed therapies may be useful as cancer management strategies. Greater expression of erbB2 on transformed cells than on normal epithelial tissues allows selective targeting of tumor cells using various approaches (5-13). A variety of strategies have also been developed for targeting the erbB1 receptor, including monoclonal antibodies, ligand-linked immunotoxins, tyrosine kinase inhibitors, and antisense approaches.Recently, we have reported the design of an anti-erbB2 peptide mimetic, AHNP, derived from the structure of the CDR-H3 loop of the anti-erbB2 monoclonal antibody 4D5 and demonstrated its in vitro and in vivo activities in disabling erbB2 tyrosine kinases similar to the monoclonal antibody (14 -16). We have argued that another interesting approach for disabling erbB receptor activity would be targeting protein-protein interaction surfaces. Because protein-protein interactions play a key role in various mechanisms of cellular growth and differentiation, and viral replication, inhibition of these interactions is a promising novel approach for rational drug design against a wide number of cellular and viral targets (17,18). Synthetic peptides that disrupt protein-protein interactions have been successfully shown to act as inhibitors of HIV-1 protease (19), HIV-1 reverse transcriptase (20), herpes simplex virus ribonucleotide reductase (21), and thymidilate synthase (22). Binding of polypeptide hormones, growth factors, or cytokines to cell surface receptors activates dimerization (oligomerization) of the receptors, which leads to the signal transduction to the interior of the cell (23). Although most of the receptor inhibitors developed to date have been focused on the blockade of receptor-ligand or enzyme-substrate interactions, repression of receptor-receptor interactions that accompany oligomerization might also represent an important target for disabling receptor functioning. This approach has been recently used for the design of peptidic estrogen receptor inhibitors ...