• Asian Pacific Journal of Cancer Prevention
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• 제13권5호
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• pp.1901-1906
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• 2012

Background: The discovery that microRNA (miRNA) regulates metastasis provide a principal molecular basis for tumor heterogeneity. A characteristic of solid tumors is their heterogenous distribution of blood vessels, with significant hypoxia occurring in regions (centers of tumor) of low blood flow. It is necessary to discover the mechanism of breast cancer metastasis in relation to the fact that there is a differential distribution of crucial microRNA in tumors from centers to edges. Methods: Breast tissues from 48 patients (32 patients with breast cancer) were classified into the high invasive and metastatic group (HIMG), low invasive and metastatic group (LIMG), and normal group. Samples were collected from both the centers and edges of all tumors. The first six specimens were detected by microRNA array, and the second ten specimens were detected by real-time qRT-PCR and Western blot analyses. Correlation analysis was performed between the miRNAs and target proteins. Results: The relative content of miR-20a and miR-20b was lower in the center of the tumor than at the edge in the LIMG, lower at the edge of the tumor than in the center in the HIMG, and lower in breast cancer tissues than in normal tissues. VEGF-A and HIF-1alpha mRNA levels were higher in the HIMG than in the LIMG, and levels were higher in both groups than in the normal group; there was no difference in mRNA levels between the edge and center of the tumor. VEGF-A and HIF-1alpha protein levels were higher in the HIMG than in the LIMG, and protein levels in both groups were higher than in the normal group; there was a significant difference in protein expression between the edge and center of the tumor. Correlation analysis showed that the key miRNAs (miR-20a and miR-20b) negatively correlated with the target proteins (VEGF-A and HIF-1alpha). Conclusions: Our data suggest that miR-20a and miR-20b are differentially distributed in breast cancer, while VEGF-A and HIF-1alpha mRNA had coincident distributions, and VEGF-A and HIF-1alpha proteins had uneven and opposing distributions to the miRNAs. It appears that one of the most important facets underlying metastatic heterogeneity is the differential distribution of miR-20a and miR-20b and their regulation of target proteins.

• Radiation Oncology Journal
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• 제12권1호
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• pp.9-16
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• 1994

마우스 종양인 SCCVll과 RIF-1에서 선택적 저산소세포 치사제인 SR 4233 (tirapazamine)과 분할 방사선조사를 병용하면 저산소분획이 큰 종양에서 방사선 감수성이 더욱 증강될 것인가를 확인하기 위하여 본 연구를 실시하였다. 종양세포 이식이전에 방사선조사를 받은 정상조직에서 성장한 종양의 저산소세포 분획이 크다는 사실을 이용하여 저산소세포분획이 큰 종양 모델을 수립 사용하였다. 일정 용적의(100$mm^{3}$) 종양에 대하여 1회 2 Gy를 1일 2회씩 6회 또는 1회 2.5 Gy를 1일 2회씩 8회 조사하는 등의 분할조사법을 사용하여 방사선조사를 시행하였다. SR 4233를 병용한 경우에는 매회 방사선조사 30분 전에 0.08 mmol/kg를 복강내 주사하였다. 정상조직에서 성장한 종양에 비하여 방사선 조사를 받은 조직에서는 성장한 종양은 분할 방사선조사에 대하여 약 5배의 내성을 보였으나 SR 4233 분할 치료에 대하여는 약 5배의 감수성을 나타내었다. 정상 종양 및 저산소세포 분획이 큰 종양의 방사선 감수성은 공통적으로 SR 4233의 병용후 증강되었으며 저산소세포 분획이 큰 종양에서의 증강율이 정상종양에서의 증강율과 동일하거나 더욱 높았다. 따라서 선택적 저산소세포 치사제인 SR 4233과 분할 방사선조사를 병용할 경우 저산소분획이 큰 종양에서 치사효과가 더욱 증강된 사실을 확인하였다. 이러한 결과는 높은 저산소세포 분획에 의한 방사선내성을 보이는 종양중 일부는 저산소세포치사제와 방사선치료를 병용함으로써 국소적 종양관해 실패의 요인인 저산소 세포를 극복하는 임상 적용 가능성을 시사한다.

• Journal of Radiation Protection and Research
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• 제43권2호
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• pp.66-74
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• 2018

Background: Tumor response to anticancer therapies can much be influenced by microenvironmental factors. In this study, we determined the effect of these microenvironmental factors on DNA methylation using A549 human lung adenocarcinoma cell line. Materials and Methods: We subjected A549 cells to various conditions mimicking tumor microenvironment including hypoxia, acidosis (sodium lactate), oxidative stress ($H_2O_2$), bystander effect (supernatant from doxorubicin (Dox)-treated or irradiated cells), and immune cell infiltration (supernatant from THP-1 or Jurkat T cells). Genomic DNA was isolated from these cells and analyzed for DNA methylation. Clonogenic cell survival, gene expression, and metabolism were analyzed in cells treated with some of these conditions. Results and Discussion: We found that DNA methylation level was significantly decreased in A549 cells treated with conditioned media from Dox-treated cells or Jurkat T cells, or sodium lactate, indicating an active transcription. To determine whether the decreased DNA methylation affects radiation sensitivity, we exposed cells to these conditions followed by 6 Gy irradiation and found that cell survival was significantly increased by sodium lactate while it was decreased by conditioned media from Dox-treated cells. We further observed that cells treated with conditioned media from Dox-treated cells exhibited significant changes in expression of genes including BAX and FAS (involved in apoptosis), NADPH dehydrogenase (mitochondria), EGFR (cellular survival) and RAD51 (DNA damage repair) while sodium lactate increased cellular metabolism rather than changing the gene expression. Conclusion: Our results suggest that various tumor microenvironmental factors can differentially influence DNA methylation and hence radiosensitivity and gene expression in A549 cancer cells.

• Journal of Gastric Cancer
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• 제17권1호
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• pp.1-10
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• 2017

Gastric cancer (GC) has high mortality owing to its aggressive nature. Tumor angiogenesis plays an essential role in the growth, invasion, and metastatic spread of GC. The aim of this work was to review the angiogenic biomarkers related to the behavior of GC, documented in the literature. A search of the PubMed database was conducted with the MeSH terms: "Stomach neoplasms/blood [MeSH] or stomach neoplasms/blood supply [MeSH] and angiogenic proteins/blood [Major]". A total of 30 articles were initially collected, and 4 were subsequently excluded. Among the 26 articles collected, 16 examined the role of vascular endothelial growth factor (VEGF), 4 studied endostatin, 3 investigated angiopoietin (Ang)-2, 2 studied the Ang-like protein 2 (ANGTPL2), and 1 each examined interleukin (IL)-12, IL-8, and hypoxia inducible factor. Regarding VEGF, 6 articles concluded that the protein was related to lymph node metastasis or distant metastases. Five articles concluded that VEGF levels were elevated in the presence of GC and decreased following tumor regression, suggesting that VEGF levels could be a predictor of recurrence. Four articles concluded that high VEGF levels were correlated with poor prognosis and lower survival rates. Ang-2 and ANGTPL2 were elevated in GC and associated with more aggressive disease. Endostatin was associated with intestinal GC. VEGF is the most extensively studied angiogenic factor. It is associated with the presence of neoplastic disease and lymph node metastasis. It appears to be a good biomarker for disease progression and remission, but not for diagnosis. The data regarding other biomarkers are inconclusive.

• Asian Pacific Journal of Cancer Prevention
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• 제16권3호
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• pp.1191-1196
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• 2015

Background: Epidermal growth factor-like domain multiple 7 (EGFL7), recently identified as a secreted protein regulated by oxygen exposure, plays a critical role in promoting metastasis of hepatocellular carcinoma (HCC). Transcatheter arterial embolization (TAE) is widely used for treatment of HCC, resulting in hypoxia in tumors and surrounding liver tissues. Accordingly, we proposed the hypothesis that there could be a relationship between expression of EGFL7 and response to TAE. Materials and Methods: We established a rabbit VX2 liver tumor model using percutaneous puncture technique guided by computed tomography. TAE and sham embolization were performed and the results were confirmed by MRI 3 weeks after inoculation. We investigated the EGFL7 expression of the two groups at 6h and 3 days after intervention by means of immunohistochemistry and Western blotting. Results: Immunohistochemical staining demonstrated that the levels of EGFL7 protein significantly increased in the TAE-treated tumors compared with the control group at 6 hours (P=0.031) and 3 days (P=0.020) after intervention. Meanwhile, the relative EGFL7 protein detected in TAE group also up-regulated compared with the control group at 6 hours (P=0.020) and 3 days (P=0.024) after intervention. Conclusions: This study reveals an increase of EGFL7 expression in rabbit VX2 liver tumors after TAE. The role of EGFL7 in HCC, especially its biological behavior after TAE, needs further investigation.

• BMB Reports
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• 제49권5호
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• pp.245-246
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• 2016

The level and activity of critical regulatory proteins in cells are tightly controlled by several tiers of post-translational modifications. HIF-1α is maintained at low levels under normoxia conditions by the collaboration between PHD proteins and the VHL-containing E3 ubiquitin ligase complex. We recently identified a new physiologically relevant mechanism that regulates HIF-1α stability in the nucleus in response to cellular oxygen levels. This mechanism is based on the collaboration between the SET7/9 methyltransferase and the LSD1 demethylase. SET7/9 adds a methyl group to HIF-1α, which triggers degradation of the protein by the ubiquitin-proteasome system, whereas LSD1 removes the methyl group, leading to stabilization of HIF-1α under hypoxia conditions. In cells from knock-in mice with a mutation preventing HIF-1α methylation (Hif1α^KA/KA), HIF-1α levels were increased in both normoxic and hypoxic conditions. Hif1α^KA/KA knock-in mice displayed increased hematological parameters, such as red blood cell count and hemoglobin concentration. They also displayed pathological phenotypes; retinal and tumor-associated angiogenesis as well as tumor growth were increased in Hif1α^KA/KA knock-in mice. Certain human cancer cells exhibit mutations that cause defects in HIF-1α methylation. In summary, this newly identified methylation-based regulation of HIF-1α stability constitutes another layer of regulation that is independent of previously identified mechanisms.

• Genomics & Informatics
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• 제2권3호
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• pp.134-141
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• 2004

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide and a typical hypervascular tumor. Therefore, it is important to find factors related to angiogenesis in the process of HCC malignancy. In order to find angiogenesis-related factors in HCC, we used combined methods of in silico prediction and an experimental assay. We analyzed 1457 genes extracted from cDNA microarray of HCC patients by text-mining, sequence similarity search and domain analysis. As a result, we predicted that 16 genes were likely to be involved in angiogenesis and then the effects of these genes were confirmed by hypoxia response element(HRE)-luciferase assay. For instant, we classified osteopontin into a potent angiogenic factor and coagulation factor XII into a significant anti­angiogenic factor. Collectively, we suggest that using a combination of in silico prediction and experimental approaches, we can identify HCC-specific angiogenesis­related factors effectively and rapidly.

• Asian Pacific Journal of Cancer Prevention
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• 제15권2호
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• pp.1057-1060
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• 2014

Adiposity is a well-recognized risk factor of type 2 diabetes and cardiovascular disease, and recently there is increasing evidence that excess body weight is an avoidable cause of cancer, including gastrointestinal, endometrial, esophageal adenocarcinoma, colorectal, postmenopausal breast, prostate, and renal malignancies. The mechanisms whereby adiposity is associated with tumor development remains not well understood. There are some most studied hypothesized mechanisms such as, high levels of insulin and free levels of insulin-like growth factors, sex hormones, adipocytokines, and inflammatory cytokines, adiposity-induced hypoxia, and so on. The potential mechanisms and conclusions in adiposity associated with increased risk for developing malignancy, and the underlying cellular and molecular mechanisms will be studied very well in the near future.

• Fisheries and Aquatic Sciences
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• 제17권3호
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• pp.305-311
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• 2014

Dieckol is a polyphenol compound isolated from brown algae that has anti-oxidant, anti-inflammatory, and anti-tumor activity. We examined the anti-angiogenic effects of dieckol in endothelial cells under hypoxic conditions. Treatment with $CoCl_2$, a hypoxic mimetic agent, increased proliferation, adhesion, migration, and tube formation in HUVECs, as well as vessel sprouting in rat aortic rings, which correlated well with increased expression of hypoxia-inducible factor 1-alpha ($HIF1{\alpha}$) and ${\beta}1$-integrin. Dieckol suppressed $CoCl_2$-induced adhesion, migration, and tube formation in HUVECs and vessel sprouting in rat aortic rings. Dieckol treatment decreased $CoCl_2$-induced overexpression of $HIF1{\alpha}$ and its downstream signaling molecules, including ${\beta}1$-integrin/Fak, Akt/eNOS, and p38 MAPK. These results suggest that dieckol is a novel angiogenesis inhibitor and a potential treatment for angiogenesis-dependent diseases in humans, such as malignant tumors.

• Journal of Microbiology and Biotechnology
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• 제30권5호
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• pp.733-738
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• 2020

Glucose deprivation and hypoxia frequently occur in solid tumor cells, including pancreatic cancer cells. Glucose deprivation activates the unfolded protein response (UPR) and causes the up-regulation of glucose-regulated protein 78 (GRP78). Induction of GRP78 has been shown to protect cancer cells. Therefore, shutting down of GRP78 expression may be a novel strategy in anticancer drug development. Based on this understanding, a screening system established for anticancer agents that exhibit selective cytotoxicity on pancreatic cancer cells under glucose-deprived conditions. To test this hypothesis, the new compounds isolated, pancastatin A (PST-A) and B (PST-B), from Ponciri Fructus. PST-A and B were identified as glabretal triterpenoid moieties by electrospray ionization mass spectrometry and nuclear magnetic resonance spectroscopic methods. PST-A and B suppressed the accumulation of the UPR hallmark gene, GRP78, during glucose deprivation. Furthermore, PST-A and B showed selective cytotoxicity on PANC-1 pancreatic cancer cells under glucose deprivation. Interestingly, PST-A and B had no effect on these cells under normal growth conditions. Our results suggest that PST-A and B act as novel therapeutic agents to induce selective cell death in glucose-deprived pancreatic cancer cells.