In mice lacking Mcl-1 specifically in hepatocytes (Mcl-1Δhep), spontaneous apoptosis caused severe liver damage. Here, we demonstrate that chronically increased apoptosis of hepatocytes coincides selleck chemicals with strong hepatocyte proliferation resulting in hepatocellular carcinoma

(HCC). Liver cell tumor formation was observed in >50% of Mcl-1Δhep mice already by the age of 8 months, whereas 12-month-old wild-type (wt) and heterozygous Mcl-1flox/wt mice lacked tumors. Tumors revealed a heterogenous spectrum ranging from small dysplastic nodules to HCC. The neoplastic nature of the tumors was confirmed by histology, expression of the HCC marker glutamine synthetase and chromosomal aberrations. Liver carcinogenesis in Mcl-1Δhep mice was paralleled by markedly increased levels of Survivin, an important regulator of mitosis which is selectively overexpressed in common

human cancers. Conclusion: This study provides in vivo evidence that increased apoptosis of hepatocytes not only impairs liver homeostasis but is also accompanied by hepatocyte proliferation and hepatocarcinogenesis. Our findings might have implications for understanding apoptosis-related human liver diseases. (HEPATOLOGY 2010.) The survival of multicellular organisms depends on the maintenance of tissue homeostasis. Under physiological conditions, apoptosis contributes to liver homeostasis Metformin concentration by removing damaged hepatocytes. Proliferation, growth, and programmed hepatocyte cell death are highly coordinated and tightly controlled events in the normal liver.1 On the one hand, increased apoptosis sensitivity contributes to liver injury. On the other hand, defective apoptosis was demonstrated to lead to excessive hepatocellular survival and has emerged as a major mechanism by which premalignant hepatocytes obtain a competitive advantage over normal liver cells.2 Various molecular alterations have been characterized

that cause an imbalance in the regulation of apoptosis. Among these are alterations in p53 signaling, expression of death receptors, growth factors, and mitochondrial integrity.3 Decreased activity of proapoptotic signaling as well as increased Dimethyl sulfoxide activity of antiapoptotic events are associated with hepatocellular carcinoma (HCC) development and progression.4 Among the main cellular changes that trigger apoptosis of hepatocytes is the permeabilization of the outer mitochondrial membrane followed by the release of proapoptotic factors.5 The B cell lymphoma-2 (Bcl-2) protein family plays a pivotal role for mitochondrial integrity and the selective interactions between proapoptotic and antiapoptotic family members regulate mitochondrial activation.6 Bcl-2 family members are similar within the Bcl-2 homology (BH) regions (BH1 through BH4) and can be divided into proapoptotic and antiapoptotic Bcl-2 proteins.