Programmed cell death (PCD) is one of the important terminal paths for the cells of metazoans, and is involved in a variety of biological events that include morphogenesis, maintenance of tissue homeostasis, and elimination of harmful cells. Dysfunction of PCD leads to various diseases in humans, including cancer and several degenerative diseases. Apoptosis is not the only form of PCD. Recent studies have provided evidence that there is another mechanism of PCD, which is associated with the appearance of autophagosomes and depends on autophagy proteins. This form of cell death most likely corresponds to a process that has been morphologically defined as autophagic PCD. The present review summarizes recent experimental evidence about autophagic PCD and discusses some aspects of this form of cell death, including the mechanisms that may distinguish autophagic death from the process of autophagy involved in cell survival.

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Multikinase inhibitor sorafenib inhibits proliferation and angiogenesis of tumors by suppressing the Raf/MEK/ERK signaling pathway and VEGF receptor tyrosine kinase. It significantly prolongs median survival of patients with advanced hepatocellular carcinoma (HCC) but the response is disease-stabilizing and cytostatic rather than one of tumor regression. To examine the mechanisms underlying the relative resistance in HCC, we investigated the role of autophagy, an evolutionarily conserved selfdigestion pathway, in hepatoma cells in vitro and in vivo. Sorafenib treatment led to accumulation of autophagosomes as evidenced by conversion from LC3-I to LC3-II observed by immunoblot in Huh7, HLF and PLC/PRF/5 cells. This induction was due to activation of autophagic flux, as there was further increase in LC3-II expression upon treatment with lysosomal inhibitors, clear decline of the autophagy substrate p62, and an mRFP-GFP-LC3 fluorescence change in sorafenib-treated hepatoma cells. Sorafenib inhibited the mammalian target of rapamycin complex 1 and its inhibition led to accumulation of LC3-II. Pharmacological inhibition of autophagic flux by chloroquine increased apoptosis and decreased cell viability in hepatoma cells. siRNA-mediated knockdown of the ATG7 gene also sensitized hepatoma cells to sorafenib. Finally, sorafenib induced autophagy in Huh7 xenograft tumors in nude mice and coadministration with chloroquine significantly suppressed tumor growth compared with sorafenib alone. In conclusion, sorafenib administration induced autophagosome formation and enhanced autophagic activity, which conferred a survival advantage to hepatoma cells. Concomitant inhibition of autophagy may be an attractive strategy for unlocking the antitumor potential of sorafenib in HCC.Sorafenib is an orally available multikinase inhibitor recently approved as the first molecular targeting compound for hepatocellular carcinoma (HCC). 1 Sorafenib inhibits Raf kinases, including Raf-1 and B-Raf, which are members of the Raf/ MEK/ERK signaling pathway, and inhibits a number of receptor tyrosine kinases involved in neo-angiogenesis and tumor progression, such as vascular endothelial growth factor receptor (VEGFR) 2, platelet-derived growth factor receptor b and c-Kit. Two randomized, placebo-controlled trials revealed that sorafenib significantly prolongs the median survival of patients with advanced HCC but the response is disease-stabilizing and cytostatic rather than one of tumor regression. 2,3 Therefore, a more detailed understanding of the mechanisms underlying both the antitumor effect and the primary resistance to this compound may provide insights that can help to improve the therapeutic outcome in HCC.Macroautophagy (hereafter referred to as autophagy) is an evolutionally conserved catabolic process that transports cellular macromolecules and organelles to a lysosomal degradation pathway. 4 It is regulated by autophagy-related (atg) genes that control the formation and maturation of a doublemembrane vesicle, autophagosome, which seq...

Sorafenib is an orally active multikinase inhibitor that targets serine and threonine, and tyrosine kinases that are involved in tumor-cell signal transduction and tumor angiogenesis. This phase I trial was conducted to evaluate the pharmacokinetics (PK), safety, and preliminary efficacy of sorafenib in Japanese patients with hepatocellular carcinoma (HCC) with underlying liver dysfunction. Patients with unresectable HCC, Child-Pugh status A or B, and adequate organ functions were treated. A single dose of sorafenib was administered, followed by a 7-day wash-out period, after which patients received either sorafenib 200 mg (cohort 1) or 400 mg (cohort 2) twice daily. The PK were investigated after a single dose and during steady state. The efficacy was evaluated using the Response Evaluation Criteria in Solid Tumors. A total of 27 patients were evaluated for PK, safety, and efficacy. Although both area under the concentration-time curve for 0-12 h and maximal concentration at steady state were slightly lower in Child-Pugh B patients than in Child-Pugh A patients, the difference was not considered to be clinically relevant. Common adverse drug events included elevated lipase, amylase, rash or desquamation, diarrhea, and hand-foot skin reaction. A dose-limiting toxicity of hand-foot skin reaction was observed in one patient (cohort 2). Among the 24 patients evaluable for tumor response, one patient (4%) achieved a partial response, 20 (83%) had stable disease, and three (13%) had progressive disease. Sorafenib demonstrated a favorable tolerability and safety profile in Japanese HCC patients. Moreover, promising preliminary antitumor activity has been observed. Finally, there were no clinically relevant differences in PK between Child-Pugh A and B patients. (Cancer Sci 2008; 99: 159-165)

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