Background: Association of the proteasome core with activators regulates proteasome activity. Results: Blm10 association increases proteasome activity toward peptides and the unstructured proteasome substrate tau-441. This process is mediated by the C terminus of Blm10. Conclusion: C-terminal docking-mediated proteasome activation by Blm10 facilitates the turnover of peptide and protein substrates. Significance: Blm10 contributes to the regulation of proteasome activity.

In patients with NSCLC treated with TKI, initial or development of an osteoblastic reaction seems to be related to a more favorable outcome. In patients with osteoblastic reactions, tumors present with clinical and biologic characteristics of better survival and response to TKI. The occurrence of osteoblastic reactions during treatment with TKI, while primary tumor and metastases are stable or in response, should not be considered as disease progression.

BACKGROUNDSemaphorins act as chemotactic cues for cell movement via their transmembrane receptors, plexins. Somatic missense mutations in the plexinB1 gene coupled with overexpression of the protein frequently occur in prostate tumors, indicating a role for plexinB1 in the pathogenesis of prostate cancer. However, the effect of semaphorin/plexin signaling is highly context dependent and whether plexinB1 acts as an inducer or inhibitor of prostate tumor progression in this context is not known.METHODSThe response of prostate cancer cell lines to plexinB1 activation was assessed in migration, invasion, proliferation and protein phosphorylation assays. Expression was assessed by quantitative RTPCR and immunoblotting.RESULTSDifferent prostate cancer cell lines respond to Sema4D (the ligand for plexinB1) in diverse ways. Activation of endogenous plexinB1 enhances migration, invasion and anchorage-independent growth of LNCaP prostate cancer cells via activation of ErbB2 and Akt. In contrast, Sema4D-stimulation decreased the motility and proliferative capacity of PC3 cells. LNCaP has a missense mutation (Thr1697Ala) in the plexinB1 gene while LNCaP-LN3, a derivative of LNCaP, expresses high levels of wild-type plexinB1 only. Sema4D stimulation increases the motility and anchorage independent growth of both cell lines, showing that these responses are not dependent on the presence of the Thr1697Ala form of plexinB1. ErbB2 and plexinB1 are expressed in primary prostate epithelial cells.CONCLUSIONSPlexinB1 signals via ErbB2 to increase the invasive phenotype of prostate cancer cells. Both wild-type and mutant forms of plexinB1 are potential targets for anti-cancer therapy in prostate tumors that express ErbB2. Prostate 73:1326–1335, 2013. © 2013 The Authors. The Prostate published by Wiley Periodicals, Inc.