These results demonstrate that pertuzumab is well tolerated, has a pharmacokinetic profile which supports 3-week dosing, and is clinically active, suggesting that inhibition of dimerization may be an effective anticancer strategy.

No abstract

Summary.The pattern and the sequence of tumour necrosis factor-a (TNFa) induced cell death in the acute T-lymphoblastic leukaemic cell line CCRF-CEM and its vinblastineresistant subline CEM/VLB 100 have been studied. Previously, we found that the CEM/VLB 100 cell line was more sensitive to TNFa-induced killing than its parental CCRF-CEM cell line. TNFa-induced cell death showed an apoptotic pattern, as detected by agarose electrophoresis, flow cytometry and transmission electron microscopy (TEM). TEM images revealed that autophagy and condensed mitochondria occurred earlier than nuclear fragmentation. The specific inhibitor of autophagy, 3-methyladenine (3MA), inhibited the formation of autophagosomes. TNFa-induced DNA fragmentation and cytolysis were completely inhibited by 10 mM 3MA. Inhibition of the fusion of lysosomes with autophagosomes by asparagine did not block TNFa-induced apoptosis. In addition, amino acid and protein deprivation enhanced TNFa-induced autophagy but not apoptosis. We propose that the early stages of autophagy are required for, but do not necessarily result in, TNFa-induced apoptosis.

The human leukemia cell lines K562, CEM, CEM/VLB 100 , human leukemic blasts, and the bladder cancer J82 cell line have different sensitivities to UV light-induced apoptosis. It is reported that resistance to UV light-induced apoptosis occurs at a point in the apoptotic pathway upstream of caspase-3 but downstream of mitochondrial cytochrome c release. It is demonstrated that the block is due to deficiency of Apaf-1, a critical member of the apoptosome. Sensitivity to apoptosis was independent of caspase-9b or XIAP (inhibitors of apoptosis proteins) expression or levels of procaspase-9. IntroductionThe apoptosome, which includes the protein Apaf-1, cytochrome c/dATP, and procaspase-9, plays a central role in the apoptotic process. [1][2][3][4][5][6][7][8] Cytochrome c is released from mitochondria into the cytosol after the induction of apoptosis by many different stimuli, including CD95, tumor necrosis factor-␣, UV irradiation, and chemotherapeutic and DNA-damaging agents. 1,9,10 Released cytochrome c associates with Apaf-1 in the presence of dATP or ATP and induces the oligomerization of Apaf-1. 4,7,11,12 This recognizes inactive procaspase-9 and forms the apoptosome, triggering autocatalytic processing of procaspase-9. 4,6,13,14 Activated caspase-9 then processes effector caspases (caspase-3, -6, and -7), which in turn cause cell collapse by cleaving a specific set of substrates. By contrast, granzyme B-induced processing of procaspase-3 does not rely on the apoptosome. 15 Cells from Apaf-1 or procaspase-9 knock-out mice are resistant to several apoptotic stimuli. 8,[16][17][18][19] Deletions of Apaf-1 or caspase-9 in ras-and myc-transformed murine cells can replicate the tumorigenic effects of p53 deletion. 8 Oncogene (such as E1A)-transformed cells have increased levels of Apaf-1 and procaspase-9 protein expression and are sensitized to etoposide-induced apoptosis. 5 Inactivation of Apaf-1 and caspase-9 substantially reduces the number of cells required to form tumors. 8 Transfection of the Apaf-1 gene into leukemic cells increases the sensitivity of cells to etoposide-induced apoptosis. 20 An endogenous, alternatively spliced isoform of caspase-9 (named caspase-9b), which lacks the central large subunit caspase domain, can interact with the caspase recruitment domain of Apaf-1 and inhibit the apoptotic process. 21 Even in the presence of functional Apaf-1 and procaspase-9, inhibitors of apoptosis, such as XIAP (inhibitors of apoptosis proteins), can prevent the proteolytic processing of procaspase-3 by blocking the cytochrome c-induced activation of procaspase-9. 22 IAPs, in turn, can be regulated by the mitochondrial protein, Smac. 23,24 These data provide strong evidence that appropriate and functional levels of Apaf-1 or procaspase-9 proteins are crucial for the inhibition of tumor progression and for maintaining the sensitivity of tumor cells to apoptosis. However, it is unknown whether variations in constitutive levels of Apaf-1 have implications for human leukemia.Human leukemic cells differ widely ...