Trivalent chromium induces autophagy by activating sphingomyelin phosphodiesterase 2 and increasing cellular ceramide levels in renal HK2 cells.

In this study, we examined the role of autophagy in the initiation of lipid increases in renal epithelial HK2 cells. We found that trivalent chromium [Cr(III)] induced autophagy by activating sphingomyelin phosphodiesterase 2 (SMPD2). SMPD2 increases levels of ceramide and other lipids. Confocal immunofluorescence microscopy showed that signals of ceramide overlapped with LC3, suggesting that ceramide might play an important role in the formation of autophagosome. In conclusion, our data indicate that Cr(III) induces autophagy via structural aberration of organelle membrane, in particular by the increase of lipid compositions in addition to autophagy-associated proteins.

Hexavalent chromium induces expression of mesenchymal and stem cell markers in renal epithelial cells.

Cr(VI) causes severe kidney damage. The patient's renal function could gradually recover by spontaneous kidney regeneration. The molecular effect of Cr(VI) on recovery of kidney cells, however, has not been clearly elucidated. Here we show that Cr(VI) induces expression of mesenchymal and stem cell markers, cell markers, such as paxillin, vimentin, α-SMA, nanog, and CD133 of HK-2 cells. Moreover, Cr(VI) activates epithelial-to-mesenchymal transition (EMT). By revealing that levels of dihydrodiol dehydrogenase were promptly reduced following Cr(VI) challenge, our data suggested that DDH could be involved in a Cr(VI)-related oxidation to generate massive reactive oxygen species and H2 O2 , and to create intracellular hypoxia, which then increased levels of SUMO-1 activating enzyme subunit 2, and sumoylation of eukaryotic elongation factor-2, to mediate the subsequent molecular and cellular responses, e.g., expression of mesenchymal and stem cell markers. Pretreatment with vitamin C reduced Cr(VI)-related cellular effects. However, no evident effect was observed when vitamin C was added following Cr(VI) challenge.

Association of anticardiolipin, antiphosphatidylserine, anti-ß2 glycoprotein I, and antiphosphatidylcholine autoantibodies with canine immune thrombocytopenia.

BACKGROUND: In humans, the presence of antiphospholipid antibodies (aPL) is frequently found in immune thrombocytopenia. The present study investigated whether aPL and any aPL subtypes are associated with canine thrombocytopenia, in particular, immune-mediated thrombocytopenia (immune thrombocytopenia) that usually manifests with severe thrombocytopenia. RESULTS: Sera were collected from 64 outpatient dogs with thrombocytopenia (Group I, platelet count 0 - 80 × 10(3)/uL), and 38 of which having severe thrombocytopenia (platelet count < 30 × 10(3)/uL) were further divided into subgroups based on the presence of positive antiplatelet antibodies (aPLT) (subgroup IA, immune thrombocytopenia, n =20) or the absence of aPLT (subgroup IB, severe thrombocytopenia negative for aPLT, n =18). In addition, sera of 30 outpatient dogs without thrombocytopenia (Group II), and 80 healthy dogs (Group III) were analyzed for comparison. Indirect ELISAs were performed to compare serum levels of aPL subtypes, including anticardiolipin antibodies (aCL), antiphosphatidylserine antibodies (aPS), antiphosphatidylcholine (aPC), and anti-ß2 glycoprotein I antibodies (aß2GPI), and antiphosphatidylinositol antibodies (aPI), among different groups or subgroups of dogs. Among outpatient dogs, aCL, being highly prevalent in outpatient dogs with thrombocytopenia (63/64, 98 %), is an important risk factor for thrombocytopenia (with a high relative risk of 8.3), immune thrombocytopenia (relative risk 5.3), or severe thrombocytopenia negative for aPLT (relative risk ∞, odds ratio 19). In addition, aPS is a risk factor for immune thrombocytopenia or severe thrombocytopenia negative for aPLT (moderate relative risks around 2), whereas aPC and aß2GPI are risk factors for immune thrombocytopenia (relative risks around 2). CONCLUSIONS: Of all the aPL subtypes tested here, aCL is highly associated with canine thrombocytopenia, including immune thrombocytopenia, severe thrombocytopenia negative for aPLT, and less severe thrombocytopenia. Furthermore, aPS is moderately associated with both canine immune thrombocytopenia and severe thrombocytopenia negative for aPLT, whereas aß2GPI, and aPC are moderately relevant to canine immune thrombocytopenia. In contrast, aPI is not significantly associated with canine immune thrombocytopenia.

Downregulated CXCL12 expression in mesenchymal stem cells associated with severe aplastic anemia in children.

The mechanisms of idiopathic severe aplastic anemia (SAA) in children are not completely understood. Insufficiency of the bone marrow microenvironment, in which mesenchymal stem cells (MSCs) are an important element, can be a potential factor associated with hematopoietic impairment. In the current study, we studied whether aberrant gene expression could be found in MSCs from children with SAA. Using microarray analysis, two different patterns of global gene expression were detected in the SAA MSCs. Fourteen genes (POLE2, HGF, KIF20A, TK1, IL18R1, KITLG, FGF18, RRM2, TTK, CXCL12, DLG7, TOP2A, NUF2, and TYMS), which are related to DNA synthesis, cytokines, or growth factors, were significantly downregulated. Further, knockdown of gene expression was performed using the small hairpin RNA (shRNA)-containing lentivirus method. We found that knockdown of CXCL12, HGF, IL-18R1, FGF18, or RRM2 expression compelled MSCs from the controls to behave like those from the SAA children, with decreased survival and differentiation potential. Among them, inhibition of CXCL12 gene expression had the most profound effects on the behavior of MSCs. Further experiments regarding re-introduction of the CXCL12 gene could largely recover the survival and differentiation potential in MSCs with inhibition of CXCL12 expression. Our findings suggest that MSCs from children with SAA exhibit aberrant gene expression profiles and downregulation of CXCL12 gene may be associated with alterations in the bone marrow microenvironment.

Human RAD23 homolog A is required for the nuclear translocation of apoptosis-inducing factor during induction of cell death.

BACKGROUND INFORMATION: During the initiation of cell death, mitochondrial protein, apoptosis-inducing factor (AIF), is transported to the nucleus. The mechanism of AIF nuclear translocation, however, is not clear. After protein synthesis, the AIF is originally targetted to the mitochondria, and the nuclear targetting is a secondary event. Therefore, we hypothesised that the nuclear translocation of AIF could be achieved by a novel pathway. RESULTS: By using yeast two-hybrid assay, we identified the human UV excision repair protein RAD23 homolog A (hHR23A) interacts with AIF and their interaction was confirmed by co-immunoprecipitation and fluorescence resonance energy transfer microscopy. Silencing the RAD23A gene expression inhibits the nuclear transportation of AIF and increases cisplatin resistance. Silencing the karyopherin alpha 2 (KPNA2) gene expression, however, did not affect the nuclear import of AIF. Moreover, 2,4-dinitrophenol inhibits staurosporine-induced nuclear translocation of AIF and increases cisplatin resistance. CONCLUSIONS: These results suggest that hHR23A is required for the nuclear translocation of AIF during induction of cell death, and this process is energy dependent, but independent of karyopherins.

Using combinatorial bioinformatics methods to analyze annual perspective changes of influenza viruses and to accelerate development of effective vaccines.

The standard World Health Organization procedure for vaccine development has provided a guideline for influenza viruses, but no systematic operational model. We recently designed a systemic analysis method to evaluate annual perspective sequence changes of influenza virus strains. We applied dnaml of PHYLIP 3.69, developed by Joseph Felsenstein of Washington University, and ClustalX2, developed by Larkin et al, for calculating, comparing, and localizing the most plausible vaccine epitopes. This study identified the changes in biological sequences and associated alignment alterations, which would ultimately affect epitope structures, as well as the plausible hidden features to search for the most conserved and effective epitopes for vaccine development. Addition our newly designed systemic analysis method to supplement the WHO guidelines could accelerate the development of urgently needed vaccines that might concurrently combat several strains of viruses within a shorter period.

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.

Therapeutic Effect of Yi-Chi-Tsung-Ming-Tang on Amyloid ß-Induced Alzheimer's Disease-Like Phenotype via an Increase of Acetylcholine and Decrease of Amyloid ß.

Alzheimer's disease (AD) is an irreversible neurodegenerative disorder characterized by amyloid accumulation, neuronal death, and cognitive impairments. Yi-Chi-Tsung-Ming-Tang (YCTMT) is a traditional Chinese medicine and has never been used to enhance cognitive function and treat neurodegenerative disorders such as senile dementia. Whether YCTMT has a beneficial role in improving learning and memory in AD patients remains unclear. The present study showed that oral administration of YCTMT ameliorated amyloid-ß- (Aß(1-40)) injection-induced learning and memory impairments in rats, examined using passive avoidance and Morris water-maze tests. Immunostaining and Western Blot results showed that continuous Aß(1-40) infusion caused amyloid accumulation and decreased acetylcholine level in hippocampus. Oral administration of medium and high dose of YCTMT 7 days after the Aß(1-40) infusion decreased amyloid accumulation area and reversed acetylcholine decline in the Aß(1-40)-injected hippocampus, suggesting that YCTMT might inhibit Aß plague accumulation and rescue reduced acetylcholine expression. This study has provided evidence on the beneficial role of YCTMT in ameliorating amyloid-induced AD-like symptom, indicating that YCTMT may offer an alternative strategy for treating AD.

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.

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

AIMS: Prostatic cancer is resistant to chemotherapy. Expression of aldo-keto reductase 1C (AKR1C) has been associated with drug resistance and disease progression in several cancers. The aim was to investigate the relationship between AKR1C expression and disease progression in prostatic cancer. METHODS AND RESULTS: From January 1996 to December 2005, 86 pathological samples were collected from patients with prostatic cancer. A tissue microarray containing 31 prostatic cancers from American patients was used for comparison between Chinese and American patients. Using immunohistochemistry, aldo-keto reductase family 1, member C2 (AKR1C2) expression was assessed in tissue sections. The AKR1C2 was determined by two-dimensional immunoblotting and DNA sequencing of reverse transcriptase-polymerase chain reaction products. The relationship between AKR1C2 expression and clinicopathological variables was statistically analysed. In vitro, the association between AKR1C2 expression and drug resistance was investigated in androgen-sensitive and androgen-insensitive prostatic cancer cells. DNA sequencing and two-dimensional immunoblotting showed that prostatic cancer expressed AKR1C2. It was overexpressed in 77 of 86 (89.5%) Chinese and in 28 of 31 (90.3%) American samples. No difference was found in AKR1C2 expression between Chinese and American prostatic cancer patients. In vitro, increased expression of AKR1C2 and prostaglandin F2α correlated with cytoprotection against anticancer drugs and lycopene. CONCLUSION: Overexpression of AKR1C2 is associated with disease progression in prostatic cancer.

Microarray detection of gene overexpression in primary spontaneous pneumothorax.

Primary spontaneous pneumothorax (PSP) often occurs after the rupture of small bullae or subpleural blebs in otherwise normal lungs. The underlying mechanism(s) remain unclear. The aim of this study was to identify genes potentially involved in the development of PSP. Microarray analysis was performed to identify specific gene expression patterns. Expression levels of genes identified to be significantly up- or down-regulated in association with PSP were confirmed by real-time polymerase chain reaction (qRT-PCR) and Western blotting. Immunohistochemistry was performed to identify lung cell types highly expressing these genes. Microarray analysis revealed that expression levels of hypoxia-inducible factor-3 alpha (HIF-3alpha) and caspase-8 were significantly up-regulated in tissue from patients with PSP, whereas interferon-gamma, interleukin (IL)-6, and IL-8 were down-regulated (all P < .05). These genes are related to hypoxia, apoptosis, and inflammation. HIF-3alpha and caspase-8 protein levels were increased in samples from patients with PSP. HIF-3alpha and caspase-8 were localized in mesothelial cells, alveolar type II pneumocytes, and bronchoalveolar epithelial cells in samples from patients with PSP. Our findings, although obviously preliminary given the small sample size, suggest that hypoxia, inflammation, and apoptosis may play important roles in the pathogenesis of PSP.

Higher Levels of Dynamin-related Protein 1 are Associated with Reduced Radiation Sensitivity of Glioblastoma Cells.

BACKGROUND: Dynamin-related protein 1 (DRP1) is a GTPase involved in mitochondrial fission, mitochondrial protein import, and drug sensitivity, suggesting an association with cancer progression. This study was conducted to evaluate the prognostic significance of DRP1 in glioblastoma multiforme (GBM). METHODS: DRP1 expression was measured by immunohistochemistry and Western blotting. Correlations between DRP1 expression and clinicopathological parameters were determined by statistical analysis. Differences in survival were compared using the log-rank test. DRP1 expression was detected in 87.2% (41/47) of the investigated patients with GBM. RESULTS: The patients with higher DRP1 levels had worse survival (p = 0.0398). In vitro, the silencing of DRP1 reduced cell proliferation, invasive potential, and radiation resistance. The addition of shikonin inhibited DRP1 expression and increased drug uptake. Moreover, shikonin reduced the nuclear entry of DNA repair-associated enzymes and increased radiation sensitivity, suggesting that reducing DRP1 expression could inhibit DNA repair and increase the radiation sensitivity of GBM cells. CONCLUSION: Our results indicate that DRP1 overexpression is a prospective radio-resistant phenotype in GBM. Therefore, DRP1 could be a potential target for improving the effectiveness of radiation therapy.

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 (DRP1(nuc)) was detected in 184 patients. A significant difference was found in cumulative survival between patients with high DRP1(nuc) levels and those with DRP1(cyt) levels (P<0.001). In vitro, hypoxia increased DRP1(nuc) 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, DRP1(nuc) 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.

HGF increases cisplatin resistance via down-regulation of AIF in lung cancer cells.

Our previous study had shown that advanced stages of lung adenocarcinomas (ADC) was frequently associated with overexpression of hepatocyte growth factor (HGF), which has multipotent and anti-apoptotic activities. In this study, we examined the effect of HGF on gene expression of apoptosis-inducing factor (AIF) and cisplatin sensitivity in lung ADC cells. Expression of AIF was determined by immunocytochemistry and confocal immunofluorescence microscopy. Our data show that addition of HGF suppressed AIF expression and increased cisplatin resistance. The effect could be through HGF receptor and its downstream effector, focal adhesion kinase (FAK). Interestingly, knockout of FAK gene increased AIF expression and drug sensitivity. Re-introduction of FAK gene, on the other hand, restored drug resistance. These results suggested that HGF might induce cisplatin resistance via c-Met to activate FAK and down-regulate AIF expression.

Expression of rTSbeta as a 5-fluorouracil resistance marker in patients with primary breast cancer.

Expression of thymidylate synthase (TS) in tumor cells is frequently suggested as an important prognostic factor for patients scheduled for chemotherapy with 5-fluorouracil (5-FU). However, clinical evidence does not fully support such an anticipation. We studied the expression of rTSbeta, a reverse orientation gene of TS, as a 5-FU resistance marker in patients with primary breast cancer. Expression of rTSbeta was examined in 129 patients with newly diagnosed breast cancer and five breast cancer cell lines by immunohistochemistry, immunocytochemistry and immunoblotting. Clinically, expression of rTSbeta was found to correlate with survival of the patients (p=0.023) when patients received chemotherapeutic regimen containing 5-FU. In vitro, rTSbeta expression was found to correlate with 5-FU resistance in breast cancer cell lines. Notably, in the 5-FU-resistant cells, rTSbeta was identified in the nucleus, whereas in the 5-FU-sensitive cells, rTSbeta was found in the cytoplasm. Nuclear localization of rTSbeta was further found to be associated with protein farnesylation. Therefore, nuclear expression of rTSbeta could be a novel 5-FU resistance marker in patients with primary breast cancer.

A missense polymorphism in porcine interferon-gamma cDNA affects antiviral activity of the protein variant.

We determined the interferon-gamma (IFN-gamma) cDNA sequence from three porcine breeds, Duroc, Landrance/Duroc hybrid, and Landrance breeds. Five single nucleotide polymorphisms (SNPs) of porcine IFN-gamma (PoIFN-gamma) were identified, respectively, at positions 269 (A/G), 376 (C/T), 426 (T/C), and 465 (T/C) of the coding sequence in Landrance/Duroc hybrid, and at position 251 (A/G) in Landrance breed. Among them, A269G and A251G polymorphisms resulted in Q67R and K61R replacements in the mature protein. PoIFN-gamma cDNAs of Duroc breed (PoIFN-gamma-W) and Landrance/Duroc hybrid (PoIFN-gamma-M), which, respectively, encoded Q67 and R67, were introduced into a prokaryotic expression vector pET32 to express recombinant PoIFN-gamma-W (rPoIFN-gamma-W) and rPoIFN-gamma-M protein variants in Escherichia coli. The identity of both protein variants was further confirmed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). We then compared bioactivities of these two recombinant proteins. Although both recombinant protein variants exhibited comparable activities in antiproliferation of PK-15 cells and in nitric oxide (NO) induction of porcine peripheral monocytes, antiviral activity of rPoIFN-gamma-W protein was significantly higher (P<0.001) than that of rPoIFN-gamma-M protein in a plaque inhibition assay using pseudorabies virus (PRV). IC50 values of rPoIFN-gamma-W and rPoIFN-gamma-M protein in anti-PRV assay were determined as 5.3+/-1.3 and 9.3+/-4.3nM, respectively. In conclusion, we have identified five novel SNPs in PoIFN-gamma cDNA, including two missense polymorphisms that result in Q67R and K61R replacements. Our results further demonstrate that Q67R can markedly reduce antiviral activity of the PoIFN-gamma protein. This is the first report that shows the functional SNP in the coding region of IFN-gamma. In the future, it is imperative to determine whether Q67R replacement in IFN-gamma may have disease association.

The role of HGF-MET pathway and CCDC66 cirRNA expression in EGFR resistance and epithelial-to-mesenchymal transition of lung adenocarcinoma cells.

BACKGROUND: Epithelial-to-mesenchymal transition (EMT) has, in recent years, emerged as an important tumor cell behavior associated with high metastatic potential and drug resistance. Interestingly, protein SUMOylation and hepatocyte growth factor could respectively reduce the effect of small molecule inhibitors on tyrosine kinase activity of mutated epidermal growth factor receptor of lung adenocarcinomas (LADC). The actual mechanism is yet to be resolved. METHODS: Immunohistochemistry was used to stain proteins in LADC specimens. Protein expression was confirmed by Western blotting. In vitro, expression of proteins was determined by Western blotting and immunocytochemistry. Levels of circular RNA were determined by reverse transcription-polymerase chain reaction. RESULTS: SAE2 and cirRNA CCDC66 were highly expressed in LADC. Expression of SAE2 was mainly regulated by EGFR; however, expression of cirRNA CCDC66 was positively regulated by FAK and c-Met but negatively modulated by nAchR7α. EGFR-resistant H1975 also highly expressed cirRNA CCDC66. Immediate response of hypoxia increased phosphorylated c-Met, SAE2, and epithelial-to-mesenchymal transition. Either activation of FAK or silencing of nAchR7α increased cirRNA CCDC66. CONCLUSIONS: HGF/c-Met regulates expression of SAE2 and cirRNA CCDC66 to increase EMT and drug resistance of LADC cells. Multimodality drugs concurrently aiming at these targets would probably provide more benefits for cancer patients.

Genetic polymorphism and gene expression of microsomal epoxide hydrolase in non-small cell lung cancer.

Genetic polymorphisms of microsomal epoxide hydrolase (mEH) have been associated with increased risk of lung cancer. However, expression of mEH and its clinical significance in non-small cell lung cancer (NSCLC) have not been investigated. In this study we investigated the expression and genetic polymorphism of mEH in non-small cell lung cancer (NSCLC) patients. Genetic polymorphism was determined by restriction fragment length polymorphism of polymerase chain reaction (PCR) products. The allelic expression pattern as well as expression level of mEH were determined by reverse transcription-PCR (RT-PCR), cDNA sequencing, sequence alignment, immunoblotting and immunohistochemistry. Genotype distributions of mEH in Taiwan's NSCLC patients were 44.4% of 340TAC/340TAC, 48.6% of 340TAC/340CAC, and 7.0% of 340CAC/340CAC in exon 3, and 80.6% of 418CAT/418CAT, 19.4% of 418CAT/418CGT and 0% of 418CGT/418CGT in exon 4. Of the 72 NSCLC biopsies analyzed, mEH was expressed in 60 (83%) surgical specimens, and the major allelic expression pattern was fast type (Tyr113) in exon 3 (90.3%) and slow type (His139) in exon 4 (100%). Immunohistochemical staining showed that mEH was expressed in 326 of 423 (77.0%) tumor (lung tissue) specimens and in 48 of 93 (51.6%) metastatic lymph nodes. A significant difference in patient survival was found when mEH expression and adriamycin-containing chemotherapy were used to group patients (p=0.0167). In conclusion, with the combination of fast type (Tyr113) and slow type (His139), the mEH enzyme expressed in most NSCLC patients may have intermediate activity. Our findings indicate that with respect to cancer risk and disease progression, the expression level of mEH is as important as genetic polymorphism. In addition, mEH expression in NSCLC could be involved in drug resistance and prognosis of patients.

Overexpression of aldo-keto reductase 1C2 as a high-risk factor in bladder cancer.

Intravesical adjuvant chemotherapy and neoadjuvant chemotherapy has been respectively administered for superficial transitional cell carcinoma (TCC) of urinary bladder and advanced TCC for years. However, the therapeutic efficacy is limited. Recently, overexpression of aldo-keto reductase (AKR) in lung, esophageal, uterine cervical and ovarian cancers was shown to be closely associated with disease progression and drug resistance. In this study, we used immunohistochemistry to determine AKR expression in pathological specimens of 347 patients with urinary bladder cancer (UBC). Some of these patients were from areas with a high risk of black foot disease (BFD), a disease that is closely associated with arsenic contamination of drinking water. The presence of AKR was confirmed by immunoblotting, matrix-assisted laser desorption/ ionization time of flight mass spectrometry (MALDI-TOF) and reverse transcription-polymerase chain reaction (RT-PCR). AKR isotype was determined by cDNA sequencing. Our results showed overexpression of AKR1C2 in 226 (65.1%) patients. BFD areas had a higher frequency of patients expressing AKR1C2 in UBC. Among AKR1C2-positive UBC, 148 (65.5%) were invasive, 70 (31.0%) were non-invasive and 8 (3.5%) were carcinoma in situ (CIS). These data indicated that AKR1C2 expression could be significantly associated with cancer invasiveness (p<0.001) and disease progression. Because BFD has been closely related to arsenic ingestion, our results suggested that continual intake of arsenic in drinking water might provoke AKR1C2 expression that could in turn induce drug resistance in UBC, and AKR1C2 could be a tumor marker for UBC.