Mitochondrial Respiratory Dysfunction Induces Claudin-1 Expression via Reactive Oxygen Species-mediated Heat Shock Factor 1 Activation, Leading to Hepatoma Cell Invasiveness.

Although mitochondrial dysfunction has been implicated in tumor metastasis, it is unclear how it regulates tumor cell aggressiveness. We have reported previously that human hepatoma cells harboring mitochondrial defects have high tumor cell invasion activity via increased claudin-1 (Cln-1) expression. In this study, we demonstrated that mitochondrial respiratory defects induced Cln-1 transcription via reactive oxygen species (ROS)-mediated heat shock factor 1 (HSF1) activation, which contributed to hepatoma invasiveness. We first confirmed the inverse relationship between mitochondrial defects and Cln-1 induction in SNU hepatoma cells and hepatocellular carcinoma tissues. We then examined five different respiratory complex inhibitors, and complex I inhibition by rotenone most effectively induced Cln-1 at the transcriptional level. Rotenone increased both mitochondrial and cytosolic ROS. In addition, rotenone-induced Cln-1 expression was attenuated by N-acetylcysteine, an antioxidant, and exogenous H2O2 treatment was enough to increase Cln-1 transcription, implying the involvement of ROS. Next we found that ROS-mediated HSF1 activation via hyperphosphorylation was the key event for Cln-1 transcription. Moreover, the Cln-1 promoter region (from -529 to +53) possesses several HSF1 binding elements, and this region showed increased promoter activity and HSF1 binding affinity in response to rotenone treatment. Finally, we demonstrated that the invasion activity of SNU449 cells, which harbor mitochondrial defects, was blocked by siRNA-mediated HSF1 knockdown. Taken together, these results indicate that mitochondrial respiratory defects enhance Cln-1-mediated hepatoma cell invasiveness via mitochondrial ROS-mediated HSF1 activation, presenting a potential role for HSF1 as a novel mitochondrial retrograde signal-responsive transcription factor to control hepatoma cell invasiveness.

Identification of a mitochondrial defect gene signature reveals NUPR1 as a key regulator of liver cancer progression.

UNLABELLED: Many cancer cells require more glycolytic adenosine triphosphate production due to a mitochondrial respiratory defect. However, the roles of mitochondrial defects in cancer development and progression remain unclear. To address the role of transcriptomic regulation by mitochondrial defects in liver cancer cells, we performed gene expression profiling for three different cell models of mitochondrial defects: cells with chemical respiratory inhibition (rotenone, thenoyltrifluoroacetone, antimycin A, and oligomycin), cells with mitochondrial DNA depletion (Rho0), and liver cancer cells harboring mitochondrial defects (SNU354 and SNU423). By comparing gene expression in the three models, we identified 10 common mitochondrial defect-related genes that may be responsible for retrograde signaling from cancer cell mitochondria to the intracellular transcriptome. The concomitant expression of the 10 common mitochondrial defect genes is significantly associated with poor prognostic outcomes in liver cancers, suggesting their functional and clinical relevance. Among the common mitochondrial defect genes, we found that nuclear protein 1 (NUPR1) is one of the key transcription regulators. Knockdown of NUPR1 suppressed liver cancer cell invasion, which was mediated in a Ca(2+) signaling-dependent manner. In addition, by performing an NUPR1-centric network analysis and promoter binding assay, granulin was identified as a key downstream effector of NUPR1. We also report association of the NUPR1-granulin pathway with mitochondrial defect-derived glycolytic activation in human liver cancer. CONCLUSION: Mitochondrial respiratory defects and subsequent retrograde signaling, particularly the NUPR1-granulin pathway, play pivotal roles in liver cancer progression.

Surgical treatment for hepatocellular carcinoma with bile duct invasion.

PURPOSE: There is still some debate on surgical procedures for hepatocellular carcinoma (HCC) patients with bile duct tumor thrombi (BDTT, Ueda type 3 or 4). What is adequate extent of liver resection for curative treatment? Is extrahepatic bile duct resection mandatory for cure? The aim of this study is to answer these questions. METHODS: Between February 1994 and December 2012, 877 consecutive HCC patients underwent hepatic resection at Ajou University Hospital. Thirty HCC patients (3.4%) with BDTT (Ueda type 3 or 4) were retrospective reviewed in this study. RESULTS: In total, 20 patients enrolled in this study were divided into 2 groups: patients who underwent hemihepatectomy with extrahepatic bile duct resection (group 1, n = 10) and with only removal of BDTT (group 2, n = 10). The 1-, 3- and 5-year overall survival rates were 75.0%, 50.0%, and 27.8%, respectively. The 1-, 3-, and 5-year survival rates of group 1 were 100.0%, 80.0%, and 45.7%, and those of group 2 were 50.0%, 20.0%, and 10.0%, respectively (P = 0.014). The 1-, 3-, and 5-year recurrences free survival rates of group 1 were 90.0%, 70.0%, and 42.0%, and those of group 2 were 36.0%, 36.0%, and 0%, respectively (P = 0.014). Thrombectomy and infiltrative growth type (Ig) were found as independent prognostic factors for recurrence free survival by multivariate analysis. Thrombectomy, Ig, and high indocyanine green retention rate at 15 minutes were found as independent prognostic factors for overall survival by multivariate analysis. CONCLUSION: We suggest that the appropriate surgical procedure for icteric HCC patients should be comprised of ipsilateral hemihepatectomy with caudate lobectomy and extrahepatic bile duct resection.

Blood Neutrophil-to-Lymphocyte Ratio Predicts Tumor Recurrence in Patients with Hepatocellular Carcinoma within Milan Criteria after Hepatectomy.

PURPOSE: The systemic inflammation biomarker, Neutrophil-to-Lymphocyte Ratio (NLR), has been reported as one of the adverse prognostic factors for hepatocellular carcinoma (HCC) patient. The purpose of this study was to evaluate whether NLR could predict the risk of recurrence and death for the HCC patient, according to Milan criteria after hepatectomy. MATERIALS AND METHODS: Retrospective analysis was performed on a database of HCC patients who underwent hepatectomy between March 2001 and December 2011. The cutoff value of NLR was decided by receiver operating characteristic (ROC) curve analysis. Univariate and multivariate regression analyses were performed to identify predictive factors of recurrence and death. RESULTS: A total of 213 patients were included in the present study. The median follow-up period was 48 months. One hundred and seven patients were experienced tumor recurrence; forty of them recurred within 12 months (early recurrence). NLR ≥1.505, albumin ≤3.75 g/dL, microvascular invasion and high grade of cirrhosis were found to be independent factors for adverse recurrence-free survival in multivariate regression analysis. And NLR ≥1.945 was also found as a prognosis factor for early recurrence by univariate regression analysis. CONCLUSION: Elevated preoperative NLR can be easily obtained and reliable biomarker for assessing the tumor recurrence and early recurrence of Milan criteria HCC after the initial hepatectomy.

Involvement of mitophagy in oncogenic K-Ras-induced transformation: overcoming a cellular energy deficit from glucose deficiency.

Although mitochondrial impairment has often been implicated in carcinogenesis, the mechanisms of its development in cancer remain unknown. We report here that autophagy triggered by oncogenic K-Ras mediates functional loss of mitochondria during cell transformation to overcome an energy deficit resulting from glucose deficiency. When Rat2 cells were infected with a retrovirus harboring constitutively active K-Ras (V12) , mitochondrial respiration significantly declined in parallel with the acquisition of transformation characteristics. Decreased respiration was not related to mitochondrial biogenesis but was inversely associated with the increased formation of acidic vesicles enclosing mitochondria, during which autophagy-related proteins such as Beclin 1, Atg5, LC3-II and vacuolar ATPases were induced. Interestingly, blocking autophagy with conventional inhibitors (bafilomycin A, 3-methyladenin) and siRNA-mediated knockdown of autophagy-related genes recovered respiratory protein expression and respiratory activity; JNK was involved in these phenomena as an upstream regulator. The cells transformed by K-Ras (V12) maintained cellular ATP level mainly through glycolytic ATP production without induction of GLUT1, the low Km glucose transporter. Finally, K-Ras (V12) -triggered LC3-II formation was modulated by extracellular glucose levels, and LC3-II formation increased only in hepatocellular carcinoma tissues exhibiting low glucose uptake and increased K-Ras expression. Taken together, our observations suggest that mitochondrial functional loss may be mediated by oncogenic K-Ras-induced mitophagy during early tumorigenesis even in the absence of hypoxia, and that this mitophagic process may be an important strategy to overcome the cellular energy deficit triggered by insufficient glucose.

The 8-kDa dynein light chain binds to p53-binding protein 1 and mediates DNA damage-induced p53 nuclear accumulation.

The tumor suppressor protein p53 is known to undergo cytoplasmic dynein-dependent nuclear translocation in response to DNA damage. However, the molecular link between p53 and the minus end-directed microtubule motor dynein complex has not been described. We report here that the 8-kDa light chain (LC8) of dynein binds to p53-binding protein 1 (53BP1). The LC8-binding domain was mapped to a short peptide segment immediately N-terminal to the kinetochore localization region of 53BP1. The LC8-binding domain is completely separated from the p53-binding domain in 53BP1. Therefore, 53BP1 can potentially act as an adaptor to assemble p53 to the dynein complex. Unlike other known LC8-binding proteins, 53BP1 contains two distinct LC8-binding motifs that are arranged in tandem. We further showed that 53BP1 can directly associate with the dynein complex. Disruption of the interaction between LC8 and 53BP1 in vivo prevented DNA damage-induced nuclear accumulation of p53. These data illustrate that LC8 is able to function as a versatile acceptor to link a wide spectrum of molecular cargoes to the dynein motor.