In newly diagnosed metastatic hormone-naive prostate cancer (mPC), telomerase-based immunotherapy with the novel hTERT peptide vaccine UV1 can induce immune responses with potential clinical benefit. This phase I dose escalation study of UV1 evaluated safety, immune response, effects on prostate-specific antigen (PSA) levels, and preliminary clinical outcome. Twenty-two patients with newly diagnosed metastatic hormone-naïve PC (mPC) were enrolled; all had started androgen deprivation therapy and had no visceral metastases. Bone metastases were present in 17 (77%) patients and 16 (73%) patients had affected lymph nodes. Three dose levels of UV1 were given as intradermal injections combined with GM-CSF (Leukine). Twenty-one patients in the intention-to-treat population (95%) received conformal radiotherapy. Adverse events reported were predominantly grade 1, most frequently injection site pruritus (86.4%). Serious adverse events considered possibly related to UV1 and/or GM-CSF included anaphylactic reaction in two patients and thrombocytopenia in one patient. Immune responses against UV1 peptides were confirmed in 18/21 evaluable patients (85.7%), PSA declined to <0.5 ng/mL in 14 (64%) patients and in ten patients (45%) no evidence of persisting tumour was seen on MRI in the prostatic gland. At the end of the nine-month reporting period for the study, 17 patients had clinically stable disease. Treatment with UV1 and GM-CSF gave few adverse events and induced specific immune responses in a large proportion of patients unselected for HLA type. The intermediate dose of 0.3 mg UV1 resulted in the highest proportion of, and most rapid UV1-specific immune responses with an acceptable safety profile. These results warrant further clinical studies in mPC.

The role of adenomatous polyposis coli (APC) tumor suppressor at mitochondria is unclear. We show that APC associates with the Miro/Milton/kinesin complex to stimulate anterograde transport of mitochondria. This identifies the first regulatory role of APC in organelle transport. APC cancer mutations block this activity.

Protein phosphatase (PP) 2A is a heterotrimeric enzyme regulated by specific subunits. The B56 (or B/PR61/PPP2R5) class of B-subunits direct PP2A or its substrates to different cellular locations, and the B56␣, -␤, and -⑀ isoforms are known to localize primarily in the cytoplasm. Here we studied the pathways that regulate B56␣ subcellular localization. We detected B56␣ in the cytoplasm and nucleus, and at the nuclear envelope and centrosomes, and show that cytoplasmic localization is dependent on CRM1-mediated nuclear export. The inactivation of CRM1 by leptomycin B or by siRNA knockdown caused nuclear accumulation of ectopic and endogenous B56␣. Conversely, CRM1 overexpression shifted B56␣ to the cytoplasm. We identified a functional nuclear export signal at the C terminus (NES; amino acids 451-469), and site-directed mutagenesis of the NES (L461A) caused nuclear retention of full-length B56␣. Active NESs were identified at similar positions in the cytoplasmic B56-␤ and ⑀ isoforms, but not in the nuclear-localized B56-␦ or ␥ isoforms. The transient expression of B56␣ induced nuclear export of the PP2A catalytic (C) subunit, and this was blocked by the L461A NES mutation. In addition, B56␣ co-located with the PP2A active (A) subunit at centrosomes, and its centrosome targeting involved sequences that bind to the A-subunit. Fluorescence Recovery after Photobleaching (FRAP) assays revealed dynamic and immobile pools of B56␣-GFP, which was rapidly exported from the nucleus and subject to retention at centrosomes. We propose that B56␣ can act as a PP2A C-subunit chaperone and regulates PP2A activity at diverse subcellular locations.Reversible protein phosphorylation is a key mechanism regulating a myriad of cellular processes. A delicate balance between the opposing effects of protein kinases and phosphatases determines the functional state of many proteins. Protein phosphatase 2A (PP2A) 3 refers to a major family of heterotrimeric serine-threonine phosphatase enzymes in the cell (1-3). The core enzyme is a dimer consisting of a 36-kDa catalytic C-subunit and a 65-kDa structural regulatory A-subunit, which acts as a scaffold to bring into proximity the C-subunit and protein substrates bound by the diverse regulatory B-subunits. There are four B-subunit gene families each with multiple genes that encode a range of splice variant peptides. The diverse nature of PP2A is inherent in its composition, which is potentially comprised of over 200 distinct protein complexes each containing different combinations of the A-, B-, and C-subunits, and hence allowing for variability and subtle regulation in phosphatase action (3).The B-subunits are postulated to regulate PP2A activity in different ways: (a) by targeting the holoenzyme to specific subcellular locations (e.g. B55␣ directs PP2A to microtubules (4)), (b) determining substrate specificity (e.g. PP2A complexes containing B55 or B72 B-subunits cause the activation or inhibition of SV40 DNA replication, respectively, because of differences in substrate recognition sites on...