Is the hypoxia-inducible factor pathway important in gastric cancer?

Metabolic codependencies in the tumor microenvironment and gastric cancer: Difficulties and opportunities

Oncogenesis and the development of tumors affect metabolism throughout the body. Metabolic reprogramming (also known as metabolic remodeling) is a feature of malignant tumors that is driven by oncogenic changes in the cancer cells themselves as well as by cytokines in the tumor microenvironment. These include endothelial cells, matrix fibroblasts, immune cells, and malignant tumor cells. The heterogeneity of mutant clones is affected by the actions of other cells in the tumor and by metabolites and cytokines in the microenvironment. Metabolism can also influence immune cell phenotype and function. Metabolic reprogramming of cancer cells is the result of a convergence of both internal and external signals. The basal metabolic state is maintained by internal signaling, while external signaling fine-tunes the metabolic process based on metabolite availability and cellular needs. This paper reviews the metabolic characteristics of gastric cancer, focusing on the intrinsic and extrinsic mechanisms that drive cancer metabolism in the tumor microenvironment, and interactions between tumor cell metabolic changes and microenvironment metabolic changes. This information will be helpful for the individualized metabolic treatment of gastric cancers.

Hypoxia-inducible factor-1α and ischemia-modified albumin levels in intensive care COVID-19 Patients

OBJECTIVES

In this study, it was aimed to evaluate the hypoxia-inducible factor-1α (HIF-1α) and ischemia-modified albumin (IMA) levels of patients diagnosed with COVID-19 in the intensive care unit (ICU) and healthy controls. To our knowledge, this is the first study investigate HIF-1α and IMA levels in COVID-19 patients in ICUs and comparing them with a healthy control group. For this reason, our study is original and will contribute to the literature.

METHODS

A total of 70 intensive care patients diagnosed with COVID-19, and 72 healthy controls were included in the study.

RESULTS

When we compared the patient and healthy control group; there were no statistically significant differences between the groups in terms of age and gender (p>0.05). No exitus was observed in the patient group. We found weak correlation between HIF-1α and IMA (r: 0.320). However, there were statistically significant differences in HIF-1α and IMA levels in the patient group. The receiver operating characteristic (ROC) curve demonstrated an area under curve (AUC) value of 0.651 for HIF-1α and 0.937 for IMA.

CONCLUSIONS

The HIF-1α and IMA levels were significantly higher among COVID-19 patients in ICU compared with healthy controls. HIF-1α and IMA levels can be used as reliable markers for the prognosis of COVID-19.

Cell death affecting the progression of gastric cancer

Gastric cancer is a gastrointestinal tumor with high morbidity and mortality rates. Several factors influence its progression, cell death being an important element. In this review, we summarized the effects of necrosis, apoptosis, necroptosis, pyroptosis, ferroptosis, and eight less common cell death modalities on gastric cancer cells and the tumor microenvironment, detailed the molecular mechanisms of various cell death and their major regulatory pathways in gastric cancer, explored the prevalence and complexity of cell death in gastric cancer progression and highlighted the potentials of cell death-related therapies in gastric cancer.

The Potential Role of Changes in the Glucose and Lipid Metabolic Pathways in Gastrointestinal Cancer Progression: Strategy in Cancer Therapy

Background

Changes in cell metabolism are a well-known feature of some cancers, and this may be involved in the etiology of tumor formation and progression, as well as tumor heterogeneity. These changes may affect fatty acid metabolism and glycolysis and are required to provide the increase in energy necessary for the high rate of proliferation of cancer cells. Gastrointestinal cancers remain a difficult-to-treat cancer, particularly as they are usually diagnosed at a late stage of disease and are associated with poor outcomes.

Summary

Recently, the changes in the metabolic pathways, including the expression of the rate-limiting enzymes involved, have been considered to be a potential target for therapy for gastrointestinal tumors.

Key Message

A combination of routine chemotherapy drugs with metabolic inhibitors may improve the effectiveness of treatment.

Pyruvate Kinase M2 Knockdown Suppresses Migration, Invasion, and Epithelial-Mesenchymal Transition of Gastric Carcinoma via Hypoxia-Inducible Factor Alpha/B-Cell Lymphoma 6 Pathway

Gastric carcinoma is a common malignant cancer. Pyruvate kinase M2 (PKM2) is highly expressed in cancers, including gastric carcinoma. However, its function and molecular mechanism in gastric carcinoma remains unclear. Here, we aimed to explore the function and the underlying mechanism of PKM2 on malignant phenotypes in gastric carcinoma. In this study, the mRNA levels and protein levels of PKM2 in gastric carcinoma cell lines and normal gastric mucosa epithelial cell lines were detected using quantitative real-time PCR and western blot, respectively. PKM2 was downregulated by siRNA transfection. HIF-1α or BCL-6 was upregulated by corresponding overexpression plasmid. Cell viability was detected using CCK-8 assay. Cell invasion and migration were determined using transwell assay. Higher expression of PKM2 was observed in human gastric carcinoma cell lines MKN-45 and SGC-7901 than in the normal gastric mucosa epithelial cell line GES-1. PKM2 knockdown suppressed cancer cell invasion and migration and inhibited the epithelial-mesenchymal transition (EMT) phenotype by inhibiting E-cadherin and promoting vimentin and N-cadherin expression. Also, we observed that PKM2 knockdown suppressed the hypoxia-inducible factor alpha (HIF-1α) and B-cell lymphoma 6 (BCL-6) signaling pathway. HIF-1α overexpression reversed the function of PKM2 silencing on cell invasion, migration, EMT, and BCL-6 expression. BCL-6 overexpression also reversed the function of PKM2 silencing on cell invasion, migration, and EMT but did not affect HIF-1α expression. Taken together, data from our study suggest that PKM2 knockdown impeded cell migration, invasion, and EMT of gastric carcinoma cells via the HIF-1α/BCL-6 pathway.

Complex Network Characterization Using Graph Theory and Fractal Geometry: The Case Study of Lung Cancer DNA Sequences

This paper discusses an approach developed for exploiting the local elementary movements of evolution to study complex networks in terms of shared common embedding and, consequently, shared fractal properties. This approach can be useful for the analysis of lung cancer DNA sequences and their properties by using the concepts of graph theory and fractal geometry. The proposed method advances a renewed consideration of network complexity both on local and global scales. Several researchers have illustrated the advantages of fractal mathematics, as well as its applicability to lung cancer research. Nevertheless, many researchers and clinicians continue to be unaware of its potential. Therefore, this paper aims to examine the underlying assumptions of fractals and analyze the fractal dimension and related measurements for possible application to complex networks and, especially, to the lung cancer network. The strict relationship between the lung cancer network properties and the fractal dimension is proved. Results show that the fractal dimension decreases in the lung cancer network while the topological properties of the network increase in the lung cancer network. Finally, statistical and topological significance between the complexity of the network and lung cancer network is shown.

Mutant p53 induces a hypoxia transcriptional program in gastric and esophageal adenocarcinoma

Despite the propensity for gastric and esophageal adenocarcinomas to select for recurrent missense mutations in TP53, the precise functional consequence of these mutations remains unclear. Here we report that endogenous mRNA and protein levels of mutant p53 were elevated in cell lines and patients with gastric and esophageal cancer. Functional studies showed that mutant p53 was sufficient, but not necessary, for enhancing primary tumor growth in vivo. Unbiased genome-wide transcriptome analysis revealed that hypoxia signaling was induced by mutant p53 in 2 gastric cancer cell lines. Using real-time in vivo imaging, we confirmed that hypoxia reporter activity was elevated during the initiation of mutant p53 gastric cancer xenografts. Unlike HIF co-factor ARNT, HIF1α was required for primary tumor growth in mutant p53 gastric cancer. These findings elucidate the contribution of missense p53 mutations in gastroesophageal malignancy and indicate that hypoxia signaling rather than mutant p53 itself may serve as a therapeutic vulnerability in these deadly set of cancers.

Adapting and Surviving: Intra and Extra-Cellular Remodeling in Drug-Resistant Gastric Cancer Cells

Despite the significant recent advances in clinical practice, gastric cancer (GC) represents a leading cause of cancer-related deaths in the world. In fact, occurrence of chemo-resistance still remains a daunting hindrance to effectiveness of the current approach to GC therapy. There is accumulating evidence that a plethora of cellular and molecular factors is implicated in drug-induced phenotypical switching of GC cells. Among them, epithelial-mesenchymal transition (EMT), autophagy, drug detoxification, DNA damage response and drug target alterations, have been reported as major determinants. Intriguingly, resistant GC phenotype may be the result of GC cell-induced tumor microenvironment (TME) remodeling, which is currently emerging as a key player in promoting drug resistance and overcoming cytotoxic effects of drugs. In this review, we discuss the possible mechanisms of drug resistance and their involvement in determining current GC therapies failure.

Current Targeted Therapies in HER2-Positive Gastric Adenocarcinoma

Gastric cancer is one of the most common types of cancer in the world, usually diagnosed at an advanced stage. Despite the advances in specific anticancer agents' development, the survival rates remain modest, even in early stages. In 15%-20% of cases, the human epidermal growth factor receptor 2 (HER2) overexpression was identified. We conducted a general review to summarize the progress that has been made in the targeted treatment of HER2-positive esogastric junction or gastric adenocarcinoma. According to our findings, trastuzumab is the only validated anti-HER2 agent in locally advanced or metastatic disease and its adjuvant effectiveness is assessed in a RTOG phase III study. In a previously treated advanced disease, the maytansine derivate TDM 1 failed to be approved as a second-line regimen, and the tyrosine kinase inhibitor, lapatinib, shows modest results. The antiangiogenics have not been analyzed in specific populations and targeting the mesenchymal-epithelial transition factor (MET) receptor, overexpressed in up to 46% of the advanced disease, seems encouraging. Regarding the checkpoint inhibitors, based on KEYNOTE 059 multilevel ongoing trial, stratified according to the HER2 and programmed death-ligand (PD-L) 1 status, pembrolizumab was approved for third-line treatment of gastric or gastroesophageal junction adenocarcinoma.

Hypothermic neuroprotections in the brain of an echolocation bat, Hipposideros terasensis

The present study aimed to investigate how bats protect their brain in a hypothermic situation. Formosan leaf-nosed bats (Hipposideros terasensis) were used in this study and treated under three conditions: room temperature (25±1°C), low temperature (4±1°C), and hibernation. The reactive oxygen species (ROS) levels in the blood and apoptosis-related proteins in the brain tissue were assessed and then compared among those bats under three conditions. Our results showed that the blood ROS levels of bats treated under conditions of low temperature and hibernation were significantly reduced compared with bats treated under the condition of room temperature. Both immunohistochemistry and immunoblotting expressions of hypoxia, inflammation, and apoptosis-related proteins in the brain tissue of bats treated under the condition of hibernation were significantly reduced compared with those bats treated under conditions of room temperature and low temperature. Thus, we suggested that bats can protect the brain in cold environment by reducing blood ROS levels and decreasing expressions of hypoxia, inflammation, and apoptosis-related proteins in the brain. Possible protection mechanisms involved in hypothermic adaptations need to be further clarified.

Hypoxia/IL-1α axis promotes gastric cancer progression and drug resistance

OBJECTIVE

The microenvironment of tumors constitutes a unique niche that promotes cancer metastasis and resistance. Two remarkable characteristics of this microenvironment are hypoxia and inflammation. Interleukin-1α (IL-1α), an important inflammatory factor, is frequently upregulated in a variety of cancers. This study aimed to investigate the expression of IL-1α in gastric cancer (GC) and explore the relationship between IL-1α and hypoxia.

METHODS

Reverse-transcription polymerase chain reaction was performed to characterize IL-1α expression in different GC cell lines under normoxia or hypoxia. IL-1α expression was characterized in relation to tumor stage and lymph node metastasis of GC and the survival of patients. The effect of IL-1α knockdown under normoxia or hypoxia on cell proliferation, migration and sensitivity to cisplatin was also evaluated. Additionally, hypoxia-inducible factor-1α (HIF-1α) expression in KATO-III cells was either upregulated by ectopic HIF-1α expression or downregulated through shHIF-1α transfection, the effects of which on IL-1α expression was subsequently evaluated.

RESULTS

There was a positive correlation between IL-1α, which was upregulated during hypoxia, and tumor stage, lymph node metastasis and resistance to cisplatin in GC. IL-1α was regulated by HIF1α, and a change in HIF1α expression altered the tumor-promoting effect of IL-1α.

CONCLUSION

The IL-1α/hypoxia axis may be a valuable target for diagnosis and treatment of GC.

In vitro Cytotoxic Activities of the Oral Platinum(IV) Prodrug Oxoplatin and HSP90 Inhibitor Ganetespib against a Panel of Gastric Cancer Cell Lines

Gastric cancer exhibits a poor prognosis and is the third most common cause of cancer death worldwide. Chemotherapy of metastatic gastric cancer is based on combinations of platinum drugs and fluoropyrimidines, with added agents. Oxoplatin is a stable oral platinum(IV) prodrug which is converted to a highly active tetrachlorido(IV) complex under acidic conditions. In the present work, we studied the cytotoxic effects of oxoplatin against a panel of four gastric cancer cell lines in vitro. Furthermore, the role of HSP90 in chemoresistance of these lines was investigated using the specific inhibitor ganetespib. The KATO-III, MKN-1, MKN-28, MKN-45 lines were used in MTT chemosensitivity, cell cycle and apoptosis assays. KATO-III is a signet ring diffuse cell type, MKN-1 an adenosquamous primary, MKN-28 a well-differentiated intestinal type and the MKN-45 a poorly differentiated, diffuse type gastric carcinoma line. Cytotoxicity was tested in MTT assays and intracellular signal transduction with proteome profiler Western blot arrays. Interactions of platinum drugs and ganetespib were calculated with help of the Chou-Talalay method. The prodrug oxoplatin revealed low activity against the four gastric cancer cell lines, whereas the platinum tetrachlorido(IV) complex and cisplatin gave IC₅₀ values of 1-3 µg/ml with increasing chemoresistance observed in the order of MKN-1, KATO-III, MKN-28 to MKN-45. With exception of KATO-III and MKN-28/oxoplatin, all other cell lines featured marked synergistic toxicity with clinically achievable concentrations of ganetespib. Oral administration of a platinum agent such as oxoplatin would be of great value for patients and care providers alike. These results suggest that the oncogene-stabilizing HSP90 chaperone represents an important mediator of chemoresistance in gastric cancer. Ganetespib reduced the phosphorylation of p53, Akt1/2/3 and PRAS40, as well as of WNK1, a kinase which regulates intracellular chloride concentrations. Intracellular chloride was reported to control proliferation of gastric cancer cell lines. Expression of MUC1 was not downregulated in contrast to the expression of CAIX, a prognostic marker in gastric cancer. In conclusion, the HSP90 inhibitor ganetespib synergizes with platinum anticancer drugs and modulates intracellular signal transduction in direction of a less proliferative and aggressive phenotype.

Targeting HER 2 and angiogenesis in gastric cancer

Gastric cancer is one of the most commonly diagnosed and the second leading cause of cancer death worldwide. Surgery combined with multimodal therapy remains the only curative therapy. However, local relapse or distant metastases occur in more than 50% of radically resected patients. Due to molecular therapies, targeting HER2 and angiogenesis, major advances in the treatment of gastric cancer could be achieved. Nevertheless, development of resistance to monoclonal antibodies, such as trastuzumab, is arising. Currently a number of promising new therapeutic are under investigation, combining chemotherapy with newly developed agents to overcome cancer resistance. In this review we report current clinical applications of targeted therapies and overview ongoing trials, investigating the use of monoclonal antibodies in (HER2 positive) gastric cancer.

Lentivirus-mediated RASSF1A expression suppresses aggressive phenotypes of gastric cancer cells in vitro and in vivo

Loss of Ras association domain family protein 1 isoform A (RASSF1A) expression is associated with the development of a variety of human cancers and the expression of carcinoembryonic antigen (CEA) frequently occurs in gastric cancer. This study investigated the effects of RASSF1A expression restoration using a hypoxia-inducible CEA promoter-driven vector on xenograft tumor growth in nude mice and on the in-vitro regulation of gastric cancer cell viability, cell cycle distribution, apoptosis, colony formation and invasion capacity. The data showed that the level of CEA mRNA and protein was much higher in gastric cancer SGC7901 cells than in a second gastric cancer cell line, MKN28, or in the MCF-10A normal epithelial breast cell line. RASSF1A expression was restored in SGC7901 cells compared with the negative control virus-infected SGC7910 cells. RASSF1A expression restoration significantly inhibited gastric cancer cell viability, colony formation and invasion capacity, but induced cell cycle arrest and apoptosis in vitro, especially under hypoxic culture conditions. At the gene level, restoration of RASSF1A expression under hypoxic culture conditions significantly suppressed matrix metalloproteinase-2 expression and prevented cyclinD1 expression. A nude mouse xenograft assay showed that the restoration of RASSF1A expression reduced gastric cancer xenograft formation and growth. In conclusion, the restoration of RASSF1A expression using a hypoxia-inducible and CEA promoter-driven vector suppressed aggressive phenotypes of gastric cancer cells in vitro and in vivo. These results suggest that LV-5HRE-CEAp-RASSF1A gene therapy may be a promising novel approach to treat advanced gastric cancer.

Both GLUT-1 and GLUT-14 are Independent Prognostic Factors in Gastric Adenocarcinoma

BACKGROUND

The role of glucose transporter 14 (GLUT-14/SLC2A14) in tumor biology is entirely unknown, and the significance of hypoxia inducible factor 1-alpha (HIF1-α) for gastric adenocarcinoma is controversial. The impact of GLUT-1/SLC2A1 has never been confirmed in a Caucasian cohort.

METHODS

Between 1996 and 2007, 124 patients underwent gastrectomy for gastric adenocarcinoma. Tumor sections were incubated with GLUT-1, GLUT-14, and HIF1-α antibodies. Expression was analyzed for correlations with histopathology, marker coexpression, and patient survival by uni- and multivariate analyses.

RESULTS

Expressions of GLUT-1, GLUT-14, and HIF1-α were detectable in 50, 77.4, and 27.1 %, respectively. Expression of GLUT-1 was associated with pT-category (p = 0.019), pN-category (p = 0.019), tubular (WHO, p = 0.008), and intestinal (Lauren classification; p = 0.002) histologic subtypes. Expression of GLUT-14 was correlated with pT category (p = 0.043), whereas HIF1-α did not show any correlation with histopathology or survival. The median survival period was 14 months (95 % confidence interval [CI] 9.2-18.8 months) for GLUT-1-positive patients and 55 months (95 % CI 25.8-84.2; p = 0.01) for GLUT-1-negative patients. An inferior prognosis also was seen for GLUT-14-positive cases compared with GLUT-14-negative cases (p = 0.004). Thus, worst survival was seen with both GLUT-1- and GLUT-14-positive expression followed by single-positive and then double-negative cases (p = 0.004). In multivariate analysis including International Union Against Cancer (UICC) stages, R category, Lauren classification, surgery alone versus neoadjuvant/perioperative chemotherapy, and marker expression as covariates, GLUT-1 (p = 0.011) and GLUT-14 (p = 0.025) kept their prognostic independence.

CONCLUSIONS

The study findings suggest that detection of GLUT-1 and GLUT-14 is of high prognostic value. It gives additional information to UICC stages and identifies patients with inferior prognosis. If confirmed in prospective studies, these markers need to be considered for future classification systems.

Clinical impact of the Warburg effect in gastrointestinal cancer (review)

Cancer cells exhibit altered glucose metabolism, termed the Warburg effect, which is described by the increased uptake of glucose and the conversion of glucose to lactate in cancer cells under adequate oxygen tension. Recent genetic and metabolic analyses have provided insights into the molecular mechanisms of genes that are involved in the Warburg effect and tumorigenesis. The aim of this review was to discuss significant molecular insights into clinical impacts of the Warburg effect such as oncogenic alterations and overexpression of transcriptional factors (c-Myc and hypoxia-inducible factor), metabolite transporters (glucose transporters) and glycolytic enzymes (hexokinases 2, pyruvate kinase M2, pyruvate dehydrogenase kinase, isozyme 1, lactate dehydrogenase A). Overexpression of transcriptional factors, metabolite transporters and glycolytic enzymes was associated with poor prognosis and may be associated with chemoradiotherapy resistance in multiple gastrointestinal cancer cell types. Novel small molecules targeting these enzymes or transporters exert anti-proliferative effects. Glycolytic enzymes and metabolite transporters may be significant biomarkers for predicting cancer prognosis and may be therapeutic targets in gastrointestinal cancer.

An insertion/deletion polymorphism within the proximal promoter of EGLN2 is associated with susceptibility for gastric cancer in the Chinese population

Gastric cancer (GC) is among the most common human malignancies and the second leading cause of cancer-related death worldwide. Accumulated evidence from molecular genetics indicates that an individual's genetic factors are involved in their susceptibility to GC. Hypoxia is a common feature of cancer and the hypoxia-inducible factor (HIF), a transcription factor that regulates oxygen homeostasis, plays key roles in the growth of solid tumors and regulating cellular responses to hypoxia. Prolyl hydroxylase (PHD1, also known as EGLN2) is one of the three enzymes capable of hydroxylating the alpha subunit of HIF and results in polyubiquitinylation and proteasomal degradation of HIF. A case-control study, including 415 GC patients and 830 healthy controls, was conducted to investigate the association between GC susceptibility with a 4-bp insertion/deletion polymorphism (rs10680577) in the proximal promoter of EGLN2. Logistic regression analysis showed that the heterozygote and the homozygote 4-bp del/del confer a significantly increased risk of GC after controlling for other covariates (adjusted odds ratio [OR]=1.35, 95% confidence interval [CI] 1.05-1.75, p=0.017; OR=2.19, 95% CI 1.15-4.18, p=0.009, respectively). Carriage of the 4-bp deletion allele was associated with a greatly increased risk of developing the disease (OR=1.38, 95% CI 1.12-1.70, p=0.002). Moreover, stratification analysis showed that the association was more prominent in smokers (adjusted OR=2.09, 95% CI=1.40-3.12, p for heterogeneity=0.01). Our data suggested that common genetic polymorphisms in EGLN2 may influence GC risk in the Chinese population. Considering the relative small sample size, replication in other populations with a larger sample size and further functional analysis are required for fully understanding the roles of EGLN2 polymorphisms in predisposition for GC.

Use of high-resolution computed tomography and positron emission tomography/computed tomography in the management of stage IA adenocarcinoma

Preoperative determination of malignant behavior is critical in choosing suitable therapeutic strategies such as sublobar resection for patients with small lung cancers. The aim of present review was to evaluate high-resolution computed tomography and fluorodeoxyglucose-positron emission tomography/computed tomography as tools for management of clinical stage IA adenocarcinoma.

Hypoxia stimulates the EMT of gastric cancer cells through autocrine TGFβ signaling

Epithelial mesenchymal transition (EMT) is considered to be correlated with malignancy of cancer cells and responsible for cancer invasion and metastasis. We previously reported that distant metastasis was associated with hypoxia in gastric cancer. We therefore investigated the effect of hypoxic condition on EMT of gastric cancer cells. Gastric cancer cells were cultured in normoxia (21% O₂) or hypoxia (1% O₂) for 24 h. EMT was evaluated as the percentage of spindle-shaped cells in total cells. Effect of transforming growth factor β1 (TGFβ1) or tyrosine kinase inhibitors on the EMT was evaluated. The expression level of TGFβ1 and TGFβR was evaluated by real time RT-PCR. The TGFβ1 production from cancer cells was measured by ELISA. Hypoxia stimulated EMT of OCUM-2MD3 and OCUM-12 cells, but not that of OCUM-2M cells. The expression level of TGFβ1 mRNA under hypoxia was significantly higher than that under normoxia in all of three cell lines. The expression level of TGFβR mRNA was significantly increased by hypoxia in OCUM-2MD3 cells, but not in OCUM-2M cells. TGFβR inhibitor, SB431542 or Ki26894, significantly suppressed EMT of OCUM-2MD3 and OCUM-12. TGFβ1 production from OCUM-2MD3 and OCUM-12 cells was significantly increased under hypoxia in comparison with that under normoxia. These findings might suggest that hypoxia stimulates the EMT of gastric cancer cells via autocrine TGFβ/TGFβR signaling.

Clinicopathological implications of the expression of hypoxia-related proteins in gastric cancer

OBJECTIVES

Tumor hypoxia confers poor prognosis of a wide range of solid tumors due to increased malignancy, increased likelihood of metastasis and treatment resistance. The aim of this study was to assess the significance of the expression of HIF-1α and HIF-1α-inducible proteins in gastric cancer and their impact on prognosis.

MATERIALS AND METHODS

The expression of HIF-1α, GLUT-1, CA-9, and iNOS proteins was analyzed by immunohistochemistry in 193 gastric adenocarcinomas (GAs) and 20 normal gastric mucosa.

RESULTS

HIF-1α, GLUT-1, CA-9 and iNOS were expressed in 52.3%, 43.0%, 57.0%, and 43.0% of GAs, respectively, which are higher than the normal counterparts except for CA-9. HIF-1α expression was positively correlated with the expression of GLUT-1, CA-9 and iNOS. GLUT-1 expression was higher in the intestinal type (p = 0.012); however, iNOS expression was higher in the less-differentiated type and the diffuse type (p = 0.006, p = 0.032, respectively). The expression of HIF-1α and GLUT-1 was significantly correlated with lymph node metastasis (p = 0.009, p = 0.008, respectively), while the expression of GLUT-1 and iNOS was significantly correlated with the depth of invasion and advanced stage (p = 0.044, p = 0.004; p = 0.009, p = 0.008, respectively). Overall survival was shorter in patients with GLUT-1 expression than in those without GLUT-1 expression, which was statistically significant by univariate analysis (p = 0.042). On multivariate analysis, however, stage was determined as the only independent prognostic marker (p < 0.001).

CONCLUSIONS

Our data suggest that overexpression of HIF-1α, GLUT-1, and iNOS may play an important role in gastric cancer progression. GLUT-1 is a potential candidate for predicting patient survival.

Hypoxia induces CXCR4 expression and biological activity in gastric cancer cells through activation of hypoxia-inducible factor-1α

Given the important role of CXCR4 in cancer metastasis, microenvironmental factors that modulate CXCR4 may have an impact on the process of tumor expansion. Hypoxia is a common feature of solid tumors and a significant microenvironmental factor that drives aggressive behavior. CXCR4 is upregulated in several cancer cells under hypoxic conditions, suggesting a relationship between tumor hypoxia and CXCR4. However, the role of hypoxia in regulating CXCR4 in gastric cancer remains poorly understood. KATO III gastric cancer cells were exposed to hypoxia or normoxia. CXCR4 expression in cells transfected with shRNA specific for HIF-1α was investigated by western blotting and flow cytometry. Wound healing, migration and invasion assays were used to assess cell motility and the chemotactic response to CXCL12, a major CXCR4 ligand. CXCR4 expression at the protein level and in the cell membrane was significantly increased in KATO III cells following exposure to hypoxia. This upregulation of CXCR4 was implicated in increased cell motility and enhanced chemotactic responses (migration and invasion) to CXCL12 treatment in vitro. The increases in CXCR4 expression and metastatic potential in gastric cancer cells exposed to hypoxia were blocked by HIF-1α-specific shRNA. Our results indicate that hypoxia upregulates CXCR4 in gastric cancer cells in a HIF-1α-dependent manner, and that upregulation of CXCR4 plays a role in cancer cell migration and invasion. Thus, disrupting the hypoxia-HIF-1α-CXCR4 axis could be an attractive therapeutic strategy for the treatment of gastric cancer.

Anti-proliferation and anti-invasion effects of diosgenin on gastric cancer BGC-823 cells with HIF-1α shRNAs

Drug resistance is a major factor for the limited efficacy of chemotherapy in gastric cancer treatment. Hypoxia-inducible factor-1α (HIF-1α), a central transcriptional factor in hypoxia, is suggested to participate in the resistance. Here, we identified a hypoxia-mimic (cobalt chloride) sensitive gastric cell line BGC-823 to explore whether diosgenin, an aglycone of steroidal saponins, can inhibit cancer cell invasion and survival of solid tumor in a hypoxic mimic microenvironment. We have shown that diosgenin is a potent candidate for decreasing the ability of invasion and survival in cobalt chloride treated BGC-823 cells. In addition, when combined with HIF-1α specific short hairpin RNA (shRNA), diosgenin can inhibit BGC-823 cells more effectively. The anti-invasion role of diosgenin may be related to E-cadherin, integrinα5 and integrin β6. These results suggest that diosgenin may be a useful compound in controlling gastric cancer cells in hypoxia condition, especially when combined with down-regulated HIF-1α.

Long Term Prognostic Implications of Expression of Glucose Transporter-1 and Hexokinase II in Patients with Stage I Uterine Leiomyosarcoma

Many malignant epithelial tumors show increased expression of glucose transporter-1 (GLUT-1) and hexokinase II (HK-II), both of which are involved in glucose metabolism. GLUT-1 levels are often correlated with prognosis in these tumors. The current retrospective study was conducted to evaluate the importance of GLUT-1 and HK-II expression in leiomyosarcoma (LMS), a malignant uterine non-epithelial tumor with a poor prognosis. The subjects were 23 patients with stage I LMS. Expression of GLUT-1 and HK-II was evaluated immunohistochemically in samples removed surgically, and the MIB-1 index was evaluated as a measure of cell proliferation. The association of these results with prognosis was examined. Twenty samples of leiomyoma (LOM), a benign non-epithelial tumor, were used as controls. Immunohistochemical expression was defined as negative staining (–), weak to sporadic staining (1+), and strong staining (2+) per microscopic field, respectively. Malignancy was evaluated in 2000 cells and the MIB-1 index was calculated. Overall survival for LMS was estimated using the Kaplan-Meier method. Of the LMS cases, 12 were GLUT-1-positive (52.2%; 2+: 2, 1+: 10) and 15 were HK-II-positive (65.2%; 2+: 1, 1+: 14). GLUT-1 expression in LMS was significantly correlated with the MIB1 index. The 10-year survival rates were 90.9% and 58.3% in GLUT-1-negative and GLUT-1-positive cases, respectively, and 75.0% and 73.3% in HK-II-positive and HK-II-negative cases, respectively. GLUT-1 expression was significantly correlated with prognosis. Cases of stage I LMS showed a significant correlation between the expression level of GLUT-1 and the MIB-1 index, an indicator of malignancy. GLUT-1-negative cases had a better prognosis than GLUT-1-positive cases, suggesting that GLUT-1 expression is an effective prognostic marker.

Glyoxalase-I is a novel prognosis factor associated with gastric cancer progression

Glyoxalase I (GLO1), a methylglyoxal detoxification enzyme, is implicated in the progression of human malignancies. The role of GLO1 in gastric cancer development or progression is currently unclear. The expression of GLO1 was determined in primary gastric cancer specimens using quantitative polymerase chain reaction, immunohistochemistry (IHC), and western blotting analyses. GLO1 expression was higher in gastric cancer tissues, compared with that in adjacent noncancerous tissues. Elevated expression of GLO1 was significantly associated with gastric wall invasion, lymph node metastasis, and pathological stage, suggesting a novel role of GLO1 in gastric cancer development and progression. The 5-year survival rate of the lower GLO1 expression groups was significantly greater than that of the higher expression groups (log rank P = 0.0373) in IHC experiments. Over-expression of GLO1 in gastric cancer cell lines increases cell proliferation, migration and invasiveness. Conversely, down-regulation of GLO1 with shRNA led to a marked reduction in the migration and invasion abilities. Our data strongly suggest that high expression of GLO1 in gastric cancer enhances the metastasis ability of tumor cells in vitro and in vivo, and support its efficacy as a potential marker for the detection and prognosis of gastric cancer.

The clinical and therapeutic implications of cancer stem cell biology

Cancer stem cells (CSCs) have provided new insights into the tumorigenesis and metastatic potential of cancer. The discovery of CSCs has provided many new insights into the complexities of cancer therapy: tumor initiation, treatment resistance, metastasis, recurrence, assessment of prognosis and prediction of clinical course. Recent rapid advances in molecular analysis have contributed to the better understanding of the molecular attributes and pathways that give CSCs their unique attributes. Use of these molecular techniques has facilitated elucidation of specific surface markers and pathways that favor propagation of CSCs - allowing for targeted therapy. Furthermore, it has been discovered that a specific microenvironment, or niche, is essential for the genesis of tumors from CSCs. Therapeutic strategies that alter these microenvironments compromise CSC proliferation and constitute another method of targeted cancer therapy. We review the clinical and therapeutic implications of CSCs, with a focus on treatment resistance and metastasis, and the emerging approaches to target CSCs and their microenvironments in order to attain improved outcomes in cancer. It is noteworthy that CSCs are the only cells capable of sustaining tumorigenesis; however, the cell of origin of cancer, in which tumorigenesis is initiated, may be distinct from CSCs that propagate the tumor.

Novel development of 5-aminolevurinic acid (ALA) in cancer diagnoses and therapy

Early detection and intervention are needed for optimal outcomes in cancer therapy. Improvements in diagnostic technology, including endoscopy, photodynamic diagnosis (PDD), and photodynamic therapy (PDT), have allowed substantial progress in the treatment of cancer. 5-Aminolevulinic acid (ALA) is a natural, delta amino acid biosynthesized by animal and plant mitochondria. ALA is a precursor of porphyrin, heme, and bile pigments, and it is metabolized into protoporphyrin IX (PpIX) in the course of heme synthesis. PpIX preferentially accumulates in tumor cells resulting in a red fluorescence following irradiation with violet light and the formation of singlet oxygen. This reaction, utilized to diagnose and treat cancer, is termed ALA-induced PDD and PDT. In this review, the biological significance of heme metabolites, the mechanism of PpIX accumulation in tumor cells, and the therapeutic potential of ALA-induced PDT alone and combined with hyperthermia and immunotherapy are discussed.

Cyclooxygenase-2, p53 and glucose transporter-1 as predictors of malignancy in the development of gallbladder carcinomas

Gallbladder carcinoma is the fifth most common malignancy of the gastrointestinal tract. The absolute characteristics of the disease are the high mortality rate due to the late discovery of a tumor and the low therapeutic possibilities except by surgical intervention. In oncology we can predict the outcome of the disease with a combination of classical standard clinico/pathological parameters (stage of the tumors, differentiation) and the intrinsic genetic and biochemical properties of the tumor. Such intrinzic properties of the tumors that are connected with the outcome of the disease are the denominators (markers). The author searched extensively for the expression and influence of 3 markers included in chronic inflammation and early carcinogenesis, cell cycle regulation and tissue hypoxia: cyclooxygenase-2 (COX-2), p53 gene and glucose transporter-1 protein (GLUT-1). The author discusses their possible role in the development as well as fighting this disease, if specific medications targeting them were available.

New insights into the mechanisms of gastric cancer multidrug resistance and future perspectives

Gastric cancer is still the second leading cause of cancer death worldwide. Chemotherapy is one of the major treatment options for advanced gastric cancer. The efficacy of chemotherapy for gastric cancer is poor due to insensitivity and the development of multidrug resistance (MDR). Gastric cancer MDR involves a large number of molecules and complex mechanisms. Classical drug-resistant molecules, such as P-glycoprotein/ABCB1 and MRP1/ABCC1, have been found to play important roles in mediating MDR in some gastric cancers. In recent years, new molecules and mechanisms have been found to be associated with the development of gastric cancer MDR and might provide new targets for tackling gastric cancer MDR. Combined use of molecularly targeted therapy with chemotherapy may offer improved outcomes for gastric cancer patients and might provide new threads of hope for gastric cancer treatment.

ERK/MAPK activation involves hypoxia-induced MGr1-Ag/37LRP expression and contributes to apoptosis resistance in gastric cancer

We previously demonstrated that hypoxia increased the hypoxia-inducible factor (HIF-1)-dependent MGr1-Ag/37LRP expression, which enhanced adhesion of gastric cancer cells to laminin, inhibited drug-induced apoptosis and caused cell adhesion-mediated drug resistance (CAM-DR). Here, we investigated the role of extracellular-regulated kinase (ERK) 1/2 in the signaling mechanisms underlying these events. We found that hypoxia activated ERK activity in vitro and in vivo. Overexpression of mitogen-activated protein kinase (MAPK) kinase (MEK), which preferentially activated ERK, mimics, in a nonadditive way, hypoxia-induced activity of MGr1-Ag/37LRP promoter and expression of MGr1-Ag/37LRP. Furthermore, U0126, the MEK inhibitor, inhibited hypoxia- and MEK-induced MGr1-Ag/37LRP promoter activity in a dose-dependent manner. MEK inhibition also reversed hypoxia- and MEK-induced HIF-1 protein and its activity in a dose-dependent manner. We also investigated reactive oxygen species signaling this response. Exogenous addition of H(2)O(2) was sufficient to activate ERK in a dose-dependent profile. Reactive oxygen species scavengers of H(2)O(2) significantly inhibited hypoxia-induced ERK or HIF-1 activation and sequential expression of MGr1-Ag/37LRP. We also investigated the signaling in hypoxia-induced cell adhesion and apoptosis induced by vincristine. Hypoxia significantly enhanced adhesion of SGC7901 cells to laminin in a time-dependent manner, which might be inhibited by the MEK inhibitor U0126 and MGr1-Ag/37LRP siRNA. Consistent with results of adhesion assay, hypoxia-resistant apoptosis might be reversed by U0126 in a dose-dependent manner. Our results suggest that hypoxia-elicited MGr1-Ag/37LRP expression activated by HIF-1 depends on ERK activation. These events are dependent of reactive oxygen intermediates.

VEGF -460T → C polymorphism and its association with VEGF expression and outcome to FOLFOX-4 treatment in patients with colorectal carcinoma

The -460T → C polymorphism of vascular endothelial growth factor (VEGF) gene significantly increases its promoter activity. A pilot study was conducted to assess the influence of this polymorphism on clinicopathological features of patients with colorectal carcinoma. In total, 228 patients were enrolled, including 100 with stage II/III colorectal carcinoma receiving curative surgery and 128 with metastatic disease. An excellent correlation in VEGF -460 genotypes based on white blood cells and tumor tissues existed, but there was no between-group difference in patients with or without colorectal carcinoma. A marked increase in intratumor and circulating VEGF levels were observed in patients with the T/C or C/C genotypes (P < 0.01), which was associated with increased extent of invasion, nodal involvement, poor histological differentiation, subsequent metastasis and shorter survival in stage II/III patients treated with curative surgery (P < 0.01). For patients with metastatic disease, this polymorphism was associated with a lower response rate to FOLFOX-4 (P = 0.03) and shorter survival (P < 0.001). By multivariate analysis, this polymorphism was identified as an independent prognostic factor (P = 0.01). These data suggest that -460T → C polymorphism of VEGF gene, by increasing VEGF expression and subsequent angiogenesis, could be a key determinant for increased tumor recurrence and a poor prognosis of patients with colorectal carcinoma. However, this study is exploratory and is not adjusted for multiple comparisons, requiring independent replication.

Expression of cyclooxygenase-2, glucose transporter-1 and angiogenesis in gallbladder carcinomas and their impact on prognosis

OBJECTIVE

To investigate the angiogenic and prognostic role of cyclooxygenase-2 (COX-2) in gallbladder carcinomas. We assume COX-2 overexpression, neoangiogenesis and glucose transporter-1 (GLUT-1) to be involved in disease progression.

MATERIAL AND METHODS

The carcinoma tissues of 56 patients with gallbladder carcinomas were studied immunohistochemically for the expression of COX-2, GLUT-1 and micro-vessel density. The results were correlated with clinico-pathological features and survival/prognosis.

RESULTS

The overexpression of COX-2 in gallbladder carcinomas was significantly associated with increased angiogenesis and GLUT-1 expression. Neither angiogenesis nor the grade of the tumour correlate significantly with poor survival. Age, gender and a strong GLUT-1 expression were significant factors of adverse prognosis.

CONCLUSIONS

Next to age and gender of patients, hypoxia of gallbladder tumours is a factor influencing survival. Among hypoxic factors, GLUT-1 expression is an important (significant) denominator of poor prognosis in gallbladder carcinomas, but not COX-2 nor angiogenesis.

Involvement of histone deacetylation in MORC2-mediated down-regulation of carbonic anhydrase IX

Carbonic anhydrase IX (CAIX) plays an important role in the growth and survival of tumor cells. MORC2 is a member of the MORC protein family. The MORC proteins contain a CW-type zinc finger domain and are predicted to have the function of regulating transcription, but no MORC2 target genes have been identified. Here we performed a DNA microarray hybridization and found CAIX mRNA to be down-regulated 8-fold when MORC2 was overexpressed. This result was further confirmed by northern and western blot analysis. Our results also showed that the protected region 4 (PR4) was important for the repression function of MORC2. Moreover, MORC2 decreased the acetylation level of histone H3 at the CAIX promoter. Meanwhile, trichostatin A (TSA) had an increasing effect on CAIX promoter activity. Among the six HDACs tested, histone deacetylase 4 (HDAC4) had a much more prominent effect on CAIX repression. ChIP and ChIP Re-IP assays showed that MORC2 and HDAC4 were assembled on the same region of the CAIX promoter. Importantly, we further confirmed that both proteins are simultaneously present in the PR4-binding complex. These results may contribute to understanding the molecular mechanisms of CAIX regulation.

Vasculogenic mimicry: a new prognostic sign of gastric adenocarcinoma. Pathol Oncol Res. 2010;16:259-266. [PMID: 20016961 DOI: 10.1007/s12253-009-9220-7]

Vasculogenic mimicry (VM) has been generally recognized as a new pattern of tumor neovascularization. It presents in many human malignancies. Till now, there is no report about VM in gastric adenocarcinoma (GAC). In this study, we collected 173 paraffin-embedded human GAC samples, with detailed follow-up and clinicopathologic data. CD31/ periodic acid-Schiff (PAS) double staining, immunohistochemical staining of CK8 & 18 and laminin were performed to validate the existence of VM in GAC. Microvascular density (MVD) and vasulogenic mimicry density (VMD) were counted respectively. VM was observed in 40 of the 173 GAC patients, especially in poorly differentiated GAC (P = 0.014). Patients with VM were prone to hematogenous metastasis and distant recurrence compared with patients without VM (P = 0.020, 0.029). Higher VMD values was also associated with hematogenous metastasis (P = 0.003). Immunohistochemical staining index (SI) of hypoxia-inducible factor 1alpha (HIF-1alpha), vascular endothelial growth factor (VEGF), matrix metalloproteinase (MMP)-2, and MMP-9 were compared between the VM and non-VM group. The SI of four factors were all higher in the VM group than those of non-VM group (P = 0.000, 0.000, 0.004, 0.009, respectively). The Kaplan-Meier survival analysis showed that the VM group has shorter life span compared with non-VM group (P = 0.022). Cox proportional hazards model indicated that the presence of VM and TNM stage were independent predictors of poor prognosis (P = 0.039 and 0.004) for GAC. In conclusion, VM exists in GAC, especially in poorly differentiated GAC. Additionally, it is an unfavorable prognostic indictor for GAC. Hypoxia may play a role in VM formation in GAC.

Spatio-temporal localization of HIF-1α and COX-2 during irradiation-induced oral mucositis in a rat model system

PURPOSE

Oral mucositis is a common side effect of radiotherapy for head and neck cancer. The purpose of this study was to examine the significance of and the relationship between hypoxia inducible factor-1alpha (HIF-1alpha) and cyclooxygenase-2 (COX-2) gene expression and the corresponding protein levels in irradiated rat mucosa.

MATERIAL AND METHODS

A Sprague-Dawley rat model of irradiation-induced oral mucositis was generated. Semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) was used to evaluate the HIF-1alpha and COX-2 mRNA level in rat buccal mucosa exposed to a fractionated irradiation regime. The Streptavidin-Biotin-Complex method was applied to delineate the in situ localization, intensity, and distribution of both proteins. The right buccal mucosa was not irradiated and used as control tissue.

RESULTS

The RT-PCR analyses demonstrated that, upon irradiation, HIF-1alpha and COX-2 expression was significantly induced in the left buccal mucosa in contrast to control buccal mucosa. Based on immunohistochemical analyses, the HIF-1alpha and COX-2 level, in situ localization, and the type of cells exhibiting the highest HIF-1alpha and COX-2 amounts appear to correlate.

CONCLUSIONS

The expression and protein levels of HIF-1alpha and COX-2 are substantially enhanced in irradiated rat mucosa and correlate with each other and with the severity of irradiation-induced oral mucositis.

The Clinicopathological Significance of Tissue Levels of Hypoxia-Inducible Factor-1α and Vascular Endothelial Growth Factor in Gastric Cancer

Background/Aims

Hypoxia-inducible factor-1α (HIF-1α) is a mediator of tumor progression. Vascular endothelial growth factor (VEGF) is the most potent angiogenic factor known to be induced by HIF-1α. We investigated the clinicopathological significance of HIF-1α and VEGF levels in biopsied gastric cancer tissue.

Methods

Endoscopic biopsy specimens from 67 patients with gastric carcinoma who underwent surgery were available for this study. Semiquantitative RT-PCR was applied to biopsied tumors and normal tissues to determine the expressions of HIF-1α and VEGF. The expression levels of HIF-1α and VEGF were evaluated using the tumor:normal (T/N) ratios of HIF-1α and VEGF mRNA. The clinicopathological variables were reviewed retrospectively.

Results

The T/N ratios of HIF-1α mRNA showed significant correlation with lymph-node metastases, distant metastases, stage, and recurrence within 3 years (p<0.05). The T/N ratios of VEGF mRNA showed significant correlation with lymph-node metastases and distant metastases (p<0.05). There was a significant correlation between the T/N ratios of HIF-1α and VEGF mRNA (r=0.72, p<0.01).

Conclusions

The increased expression of HIF-1α and VEGF mRNA could reflect aggressive tumor behavior, including the recurrence of gastric cancer. Examination of HIF-1α mRNA in biopsy specimens by RT-PCR assay might provide useful preoperative information on tumor aggressiveness.

Effects of HIF-1alpha on human gastric cancer cell apoptosis at different CO(2) pressures

The effects and potential molecular mechanisms underlying carbon dioxide (CO(2)) pneumoperitoneum on gastric cancer cell apoptosis are not fully understood. In this study, we assessed the effects of CO(2) pneumoperitoneum on the apoptosis of MKN-45 gastric cancer cells. Additionally, we investigated the role of HIF-1alpha in CO(2) pneumoperitoneum-induced apoptosis of gastric cancer cells. MKN-45 cells were cultured in CO(2) or air pneumoperitoneum at 0, 12 and 15 mmHg pressures for 4 h. We observed a change in cells morphology and increasing apoptotic ratios in MKN-45 cells when they were put into a 15 mmHg CO(2) pneumoperitoneum environment. However, there was no significant difference between the 0, 12 mmHg CO(2) pneumoperitoneum and the control groups. Exposure to 15 mmHg CO(2) pneumoperitoneum significantly enhanced the expression levels of HIF-1alpha and Bax, while it attenuated Bcl-2 expression levels. When we inhibited HIF-1alpha by small interfering RNA (siRNA), we found that the apoptotic ratio of MKN-45 cells decreased in 15 mmHg CO(2) pneumoperitoneum. This treatment markedly elevated Bcl-2 levels and decreased Bax expression. These data suggest that CO(2) pneumoperitoneum may accelerate the apoptosis of MKN-45 cells at higher pressures. HIF-1alpha is a crucial factor that affects gastric cancer cell apoptosis by downregulating the Bcl-2/Bax ratio.

Darbepoetin in the control of cancer-related anaemia

A group of 62 patients with different advanced cancers and with an anaemic condition were treated with a short course of darbepoetin administered on two different schedules as supportive therapy. The response rates (i.e. a haemoglobin increase of at least 1 g in 1 month) were 45.7% overall, 52.3% with weekly administration and 39% with 3-weekly administration. Darbepoetin activity was higher in men than in women, in younger patients than in older patients and in moderately anaemic patients than in severely anaemic patients, but these differences were not significant. Darbepoetin administration appears to be useful in rapidly reversing anaemia related to advanced cancer. However, the results reported in the literature for alpha-erythropoietin remain more appealing.

Lactate dehydrogenase-5 (LDH-5) expression in human gastric cancer: association with hypoxia-inducible factor (HIF-1alpha) pathway, angiogenic factors production and poor prognosis

BACKGROUND

Lactate-dehydrogenase-5 (LDH-5) is an important isoenzyme converting pyruvate to lactate under hypoxic conditions and might play an important role in the development and progression of malignancies. However, the role of LDH-5 in gastric cancer is still unclear. In this study, we investigated the clinical significance of LDH-5 expression in gastric carcinoma.

METHODS

LDH-5 expression in 152 patients with different grade and stage gastric carcinoma was analyzed by immunohistochemistry. In addition, hypoxia-inducible factor 1alpha (HIF-1alpha) as a marker of tumor hypoxia, as well as vascular endothelial growth factor (VEGF) and cyclooxygenase-2 (COX-2) as angiogenesis parameters were also assessed in this study. Correlations between the expression of investigated proteins and various clinicopathological factors including survival were determined.

RESULTS

There were 94 cases (61.8%) showing high LDH-5 expression, and 95 patients (62.5%) had high HIF-1alpha expression. Positive correlation was found between LDH-5 expression and HIF-1alpha, VEGF, and COX-2. The overexpression of LDH-5 was more prevalent in advanced tumors having positive vessel invasion. Patients with overexpression of LDH-5 showed far lower disease-free (63.5% vs 82.7%) and overall (56.3% vs 78.4%) survival rates compared with patients with low LDH-5 expression. HIF-1alpha expression was shown to have no significance on survival. In multivariate analysis, high LDH-5 expression kept its independence as a negative prognostic indicator.

CONCLUSION

The results of the current study show that LDH-5 expression may be a useful prognostic factor for patients with gastric carcinoma.

Molecular mechanisms for discrete nitric oxide levels in cancer

Nitric oxide (NO) has been invoked in nearly every normal and pathological condition associated with human physiology. In tumor biology, nitrogen oxides have both positive and negative affects as they have been implicated in both promoting and preventing cancer. Our work has focused on NO chemistry and how it correlates with cytotoxicity and cancer. Toward this end, we have studied both concentration- and time-dependent NO regulation of specific signaling pathways in response to defined nitrosative stress levels that may occur within the tumor microenvironment. Threshold levels of NO required for activation and stabilization of key proteins involved in carcinogenesis including p53, ERK, Akt and HIF have been identified. Importantly, threshold NO levels are further influenced by reactive oxygen species (ROS) including superoxide, which can shift or attenuate NO-mediated signaling as observed in both tumor and endothelial cells. Our studies have been extended to determine levels of NO that are critical during angiogenic response through regulation of the anti-angiogenic agent thrombospondin-1 (TSP-1) and pro-angiogenic agent matrix metalloproteinase-9 (MMP-9). The quantification of redox events at the cellular level has revealed potential mechanisms that may either limit or potentiate tumor growth, and helped define the positive and negative function of nitric oxide in cancer.

X irradiation combined with TNF alpha-related apoptosis-inducing ligand (TRAIL) reduces hypoxic regions of human gastric adenocarcinoma xenografts in SCID mice

Our previous study showed that X irradiation induced the expression of death receptor DR5 on the cell surface in tumor cell lines under not only normoxia but also hypoxia. X irradiation combined with TNF alpha-related apoptosis-inducing ligand (TRAIL), which is the ligand of DR5, induced apoptosis in vitro (Takahashi et al., (2007) Journal of Radiation Research, 48: 461-468). In this report, we examined the in vivo antitumor efficacy of X irradiation combined with TRAIL treatment in tumor xenograft models derived from human gastric adenocarcinoma MKN45 and MKN28 cells in SCID mice. X irradiation combined with TRAIL synergistically suppressed the tumor growth rates in the xenograft models derived from MKN45 and MKN28 cells, which have wild type Tp53 and mutated Tp53, respectively, indicating that the antitumor effects occurred in a Tp53-independent manner. Histological analysis showed that the combination of X irradiation and TRAIL induced caspase-3-dependent apoptotic cell death. Moreover, the immunohistochemical detection of hypoxic regions using the hypoxic marker pimonidazole revealed that caspase-3-dependent apoptosis occurred in the hypoxic regions in the tumors. These results indicated that X irradiation combined with TRAIL may be a useful treatment to reduce tumor growth in not only normoxic but also hypoxic regions.

Hypoxia-associated markers in gastric carcinogenesis and HIF-2alpha in gastric and gastro-oesophageal cancer prognosis

The study investigated hypoxia-associated markers (HIF-2α, Epo, Epo-R, Glut-1 and VEGF) along with Ki-67 in a gastric carcinogenesis model, and the prognostic significance of hypoxia-inducible factor (HIF)-2α in surgically treated gastro-oesophageal cancer. Protein expression was examined using immunohistochemistry on formalin-fixed, paraffin-embedded biopsies of normal mucosa (n=20), Helicobacter pylori-associated gastritis (n=24), intestinal metaplasia (n=24), dysplasia (n=12) and intestinal (n=19) and diffuse (n=21) adenocarcinoma. Relationships between HIF-2α expression and prognosis were assessed in resection specimens from 177 patients with gastric and gastro-oesophageal junction adenocarcinoma. Expression of all markers increased with progression along the gastric carcinogenesis sequence (P=0.0001). Hypoxia-inducible factor-2α was expressed in 63% of 177 resection specimens and at a high level in 44%. The median overall survival in patients with HIF-2α-expressing tumours was 22 (95% CI 18−26) months, whereas those with HIF-2α-negative tumours had a median survival of 37 (95% CI 29−44) months (P=0.015). Hypoxia-inducible factor-2α had no independent prognostic significance in multivariate analysis. In view of the lack of independent prognostic significance, HIF-2α has no role as a routine prognostic indicator. However, the high expression of HIF-2α suggests that it may be of value as a potential therapeutic target.