Kuan-Chih Chow

Nuclear expression of dynamin-related protein 1 in lung adenocarcinomas

Dynamin-related protein 1 (DRP1), an 80 kDa GTPase, is involved in mitochondrial fission and anticancer drug-mediated cytotoxicity, which implicate an association with disease progression of cancer. In this study we investigated the prognostic value of DRP1 in lung adenocarcinomas. Using immunohistochemistry, we measured the expression of DRP1 in 227 patients with lung adenocarcinomas. Expression of DRP1 was confirmed by immunoblotting. The correlation between DRP1 expression and clinicopathological parameters was analyzed by statistical analysis. Difference of survivals between different groups was compared by a log-rank test. The results showed that DRP1 expression was detected in 202 patients with lung adenocarcinomas. Among these, nuclear DRP1 (DRP1nuc) was detected in 184 patients. A significant difference was found in cumulative survival between patients with high DRP1nuc levels and those with DRP1cyt levels (P<0.001). In vitro, hypoxia increased DRP1nuc levels and cisplatin resistance. Antibodies specific to DRP1 co-precipitated a human homologue of yeast Rad23 protein A (hHR23A) and silencing of hHR23A decreased the nuclear DRP1 level and cisplatin resistance. In conclusion, DRP1nuc is highly expressed in lung adenocarcinomas, and correlates with poor prognosis. Nuclear DRP1 may increase drug resistance during hypoxia, and hHR23A is essential for nuclear transportation of DRP1. Our results suggest that other than the protein level alone, intracellular distribution of the protein is critical for determining the protein function in cells.

ATPase family AAA domain-containing 3A is a novel anti-apoptotic factor in lung adenocarcinoma cells

AAA domain-containing 3A (ATAD3A) is a member of the AAA-ATPase family. Three forms of ATAD3 have been identified: ATAD3A, ATAD3B and ATAD3C. In this study, we examined the type and expression of ATAD3 in lung adenocarcinoma (LADC). Expression of ATAD3A was detected by reverse transcription-polymerase chain reaction, immunoblotting, immunohistochemistry and confocal immunofluorescent microscopy. Our results show that ATAD3A is the major form expressed in LADC. Silencing of ATAD3A expression increased mitochondrial fragmentation and cisplatin sensitivity. Serum deprivation increased ATAD3A expression and drug resistance. These results suggest that ATAD3A could be an anti-apoptotic marker in LADC.

Detection of cytomegalovirus infection in a patient with febrile ulceronecrotic Mucha-Habermann's disease

Abstract

HIV-1 Vpr Triggers Mitochondrial Destruction by Impairing Mfn2-Mediated ER-Mitochondria Interaction

Human immunodeficiency virus 1 (HIV-1) viral protein R (Vpr) has been shown to induce host cell death by increasing the permeability of mitochondrial outer membrane (MOM). The mechanism underlying the damage to the mitochondria by Vpr, however, is not clearly illustrated. In this study, Vpr that is introduced, via transient transfection or lentivirus infection, into the human embryonic kidney cell line HEK293, human CD4+ T lymphoblast cell line SupT1, or human primary CD4+ T cells serves as the model system to study the molecular mechanism of Vpr-mediated HIV-1 pathogenesis. The results show that Vpr injures MOM and causes a loss in membrane potential (MMP) by posttranscriptionally reducing the expression of mitofusin 2 (Mfn2) via VprBP-DDB1-CUL4A ubiquitin ligase complex, gradually weakening MOM, and increasing mitochondrial deformation. Vpr also markedly decreases cytoplasmic levels of dynamin-related protein 1 (DRP1) and increases bulging in mitochondria-associated membranes (MAM), the specific regions of endoplasmic reticulum (ER) which form physical contacts with the mitochondria. Overexpression of Mfn2 and DRP1 significantly decreased the loss of MMP and apoptotic cell death caused by Vpr. Furthermore, by employing time-lapse confocal fluorescence microscopy, we identify the transport of Vpr protein from the ER, via MAM to the mitochondria. Taken together, our results suggest that Vpr-mediated cellular damage may occur on an alternative protein transport pathway from the ER, via MAM to the mitochondria, which are modulated by Mfn2 and DRP1.

Human papillomavirus infection and expression of ATPase family AAA domain containing 3A, a novel anti-autophagy factor, in uterine cervical cancer

Our aim was to determine the association of human papillomavirus (HPV) infection with the expression of ATPase family AAA domain containing 3A (ATAD3A), an anti-autophagy factor, in uterine cervical cancer (UCC). The HPV genotype was determined by an Easychip HPV blot assay. ATAD3A expression was determined by immunohistochemical staining. High-risk HPV (hrHPV) was detected in 184 (88.9%) of 207 UCC cases. ATAD3A expression was detected in 164 (79.2%) UCC cases. A significant correlation was found between ATAD3A expression and the presence of hrHPV (p<0.001), FIGO stage (p=0.014), lymph node involvement (p=0.001), c-MET expression (p<0.001), interleukin-8 (p=0.03) and patient survival (p=0.0016). Interestingly, silencing of E6/E7 expression decreased ATAD3A expression and cell survival. Moreover, knockdown of ATAD3A (ATAD3Akd) expression or addition of resveratrol, increased cellular autophagy and apoptosis and reduced drug resistance. Resveratrol reduced ATAD3A expression, and increased abrasion of the mitochondrial outer membrane as well as numbers of autophagosomes, the phenomena that were frequently found in ATAD3Akd cells. In conclusion, our results show that HPV infection correlates with increased ATAD3A expression and drug resistance in UCC. Persistent HPV infection may stabilize ATAD3A expression to inhibit cell autophagy and apoptosis as well as to increase drug resistance.

Sumoylation of eukaryotic elongation factor 2 is vital for protein stability and anti-apoptotic activity in lung adenocarcinoma cells

By screening mouse monoclonal antibody libraries for Kelch repeats, we serendipitously identified monoclonal antibodies to eukaryotic elongation factor 2 (eEF2). Interestingly, eEF2 was highly expressed in lung adenocarcinoma (LADC), but not in the neighboring non‐tumor lung tissue. Normally, eEF2 is involved in the peptidyl‐tRNA translocation during protein synthesis. Overexpression of eEF2 would implicate an association with disease progression of LADC. In the present study, we investigated the prognostic significance of eEF2 in patients with LADC. Expression of eEF2 was detected by immunoblotting, immunohistochemistry and confocal immunofluorescence microscopy. Our results show that patients with high eEF2 expression had a significantly higher incidence of early tumor recurrence (67.8%vs 18.2%, P = 0.016), and a significantly worse prognosis (P < 0.001). In an in vitro study, silencing of eEF2 expression increased mitochondrial elongation, cellular autophagy and cisplatin sensitivity. Moreover, eEF2 was sumoylated in LADC cells, and eEF2 sumoylation correlated with drug resistance. These results suggest that eEF2 is an anti‐apoptotic marker in LADC. However, biological function and involvement of eEF2 in the disease progression of LADC require further studies. (Cancer Sci 2011; 102: 1582–1589)

An alternative import pathway of AIF to the mitochondria

In eukaryotic cells, transport of the newly synthesized proteins and phospholipids to the appropriate subcellular target compartments is essential for maintaining organelle morphology and cell survival. In animal cells, mitochondria are major organelles containing DNA genome that encodes only for a small fraction of their proteins, which are required for the organelle function. Most mitochondrial proteins are encoded by the nuclear genes and imported to the mitochondria following protein synthesis. Apoptosis-inducing factor (AIF), an essential FAD-dependent NADH oxidase for the oxidative phosphorylation, is located in the intermembranous space and contains mitochondrial localization signals. However, the import mechanism of AIF to the mitochondria is not yet studied. Using sucrose gradient ultracentrifugation and immunoblotting, AIF was detected in fractions of the endoplasmic reticulum, mitochondria-associated membranes (MAM) and mitochondria, and AIF from these fractions was resistant to trypsin in the absence of digitonin, suggesting that AIF could be protected by phospholipids. Knockdown of dynamin-related protein 1 (DRP1kd) expression reduced AIF levels in the mitochondria, but increased AIF concentrations in the MAM. Knockdown of mitofusin-2 (Mfn-2kd) or ATPase family AAA domain containing 3A (ATAD3Akd) expression, however, reduced AIF levels in the mitochondria and increased the number of transport vesicles that contained AIF in the cytosol, indicating that ATAD3A and Mfn-2 were respectively essential for the import and fusion of transport vesicles into the mitochondria. Here we show that AIF is imported from the endoplasmic reticulum to the mitochondria via mitochondria-associated membranes and transport vesicles.

Overexpression of aldo-keto reductase 1C2 is associated with disease progression in patients with prostatic cancer

Huang K‐H, Chiou S‐H, Chow K‐C, Lin T‐Y, Chang H‐W, Chiang I‐P & Lee M‐C
(2010) Histopathology 57, 384–394
Overexpression of aldo‐keto reductase 1C2 is associated with disease progression in patients with prostatic cancer

Expression of short-form oncostatin M receptor as a decoy receptor in lung adenocarcinomas.

Oncostatin M (OSM) is a member of the interleukin‐6 (IL‐6) family of cytokines, and binds to the OSM receptor (OSMR) to inhibit cancer growth. Four forms of OSMR have been identified: leukemia inhibitory factor receptor (LIFR), OSMRβ, short‐form OSMR (OSMRs) and soluble OSMR (sOSMR). In this study, we examined the type and expression of OSMR in lung adenocarcinomas (LADCs). Expression of OSMR was determined by reverse transcription–polymerase chain reaction (RT–PCR), immunoblotting, immunohistochemistry and confocal immunofluorescent microscopy (CIM). Our results showed that, among the four forms of OSMR, OSMRs was mainly expressed in LADC, and expression level of OSMRs correlated with patient survival. CIM revealed that OSMRs was localized on the cell membrane of LADC cell lines in vitro. OSMRs acts as a decoy receptor by reducing the inhibitory effect of OSM on cell growth. Decrease in OSMRs expression by siRNA increased cell sensitivity to OSM, and ectopic expression of OSMRs reduced cell sensitivity to OSM. These results suggest that expression of OSMRs, which operates as a decoy receptor for OSM, is correlated with disease progression and adverse prognosis in patients with LADC. Copyright

Hepatocyte growth factor and HER2/neu downregulate expression of apoptosis-inducing factor in non-small cell lung cancer

Our previous study showed that patients with advanced stages of non-small cell lung cancer (NSCLC) were frequently detected with upregulation of hepatocyte growth factor (HGF). In vitro, HGF reduced expression of apoptosis-inducing factor (AIF) and cisplatin sensitivity in NSCLC cells. The effect of HGF was via HGF receptor (c-MET) and the downstream effector, focal adhesion kinase (FAK). In this study, we determined the prognostic value of AIF in NSCLC patients. AIF expression was determined by immunohistochemistry and immunoblotting. Our data show that AIF expression was associated with better prognosis. Expression of AIF inversely correlated with that of positive NSCLC markers, e.g., dihydrodiol dehydrogenase (DDH), c-MET, short oncostatin M receptor (OSMRs), matrix metalloproteinase (MMP)-1, and HER2/neu, which were closely associated with drug resistance, tumor recurrence, metastasis and poor prognosis. Noteworthy, silence of HER2/neu gene expression increases AIF level and drug sensitivity. Addition of HGF inhibits AIF expression in HER2/neu-silenced cells. These results suggested that both HGF and HER2/neu affect drug resistance by regulating AIF expression in NSCLC.