The aim of this study was to determine the beneficial effect of propofol on human keratinocytes that have undergone hypoxia reoxygenation (H/R) injury and to investigate whether autophagy is associated with the protective mechanism. Thus, we evaluated how propofol influences the intracellular autophagy and apoptosis during the H/R process in the HaCaT cells. The cultured human keratinocyte cells were exposed to 24 h of hypoxia (5% CO2, 1% O2, 94% N2) followed by 12 h of reoxygenation (5% CO2, 21% O2, 74% N2). The experiment was divided into 4 groups: (1) Control=Normoxia ; (2) H/R=Hypoxia Reoxygenation ; (3) PPC+H/R=Propofol Preconditioning+Hypoxia Reoxygenation; (4) 3-MA+PPC+ H/R=3-MA-Methyladenine+Propofol Preconditioning+ Hypoxia Reoxygenation. In addition, Western blot analysis was performed to identify the expression of apoptotic pathway parameters, including Bcl-2, Bax, and caspase 3 involved in mitochondrial-dependent pathway. Autophagy was determined by fluorescence microscopy, MDC staining, AO staining, and western blot. The H/R produced dramatic injuries in keratinocyte cells. In our study, the viability of Propofol in H/R induced HaCaT cells was first studied by MTT assay. The treatment with 25, 50, and 100 μM Propofol in H/R induced HaCaT cells enhanced cell viability in a dose-dependent manner and 100 μM was the most effective dose. The Atg5, Becline-1, LC3-II, and p62 were elevated in PPC group cells, but H/R-induced group showed significant reduction in HaCaT cells. The Atg5 were increased when autophagy was induced by Propofol, and they were decreased when autophagy was suppressed by 3-MA. These data provided evidence that propofol preconditioning induced autophagy and reduced apoptotic cell death in an H/R model of HaCaT cells, which was in agreement with autophagy playing a very important role in cell protection.

Lysyl oxidase (LOX) is an extracellular amine oxidase catalyzing formation of lysine-derived cross-linkages in collagen and elastin in extracellular matrices. Four human paralogs of LOX (LOXL1, LOXL2, LOXL3, and LOXL4) have been identified, each encoding the functional domains required for the amine oxidase activity of LOX. Upregulated expression of LOX and LOXL2 was reported to show significant correlation with absence of lymphovascular invasion in tumor tissues from patients with colorectal adenocarcinoma, suggesting that oxygen tension around tumors may be an important factor in expressional regulation of these genes in colorectal carcinomas. To evaluate the effects of hypoxia on expression of LOX and LOXL2 in colorectal carcinomas, we performed promoter assays and RT-PCR analysis under hypoxia in colorectal carcinoma cell lines, HT-29 and HCT-116. Expression of LOX was upregulated under hypoxia in both HT-29 and HCT-116 cells, whereas LOXL2 expression was not affected by hypoxia in those cells. In the highly metastatic HCT-116 cells, LOX showed a higher level of upregulation than in HT-29 cells, suggesting a possible association of LOX upregulation with increased invasiveness and metastatic potential in colorectal carcinomas.

Tumor cells, especially in a malignant form, proliferate rapidly that blood supply within the tumors becomes limited, leading to a condition of insufficient oxygen supply. Such hypoxic condition is known to impair the viability of cancer cells, but it can also be a factor to facilitate the appearance of cells with a higher degree of malignancy. Indeed, the hypoxic condition created within malignant tumors may contribute to promoting their aggressive behaviors, including tumor invasion and metastasis, and to the development of resistance to various therapeutic modalities such as chemotherapy. Recently, microRNAs, a group of short RNA fragments consisting of 18 to 20 nucleotides, have been shown to participate in regulating genes important for cell survival, differentiation and apoptosis. Since their discovery, modulation of these microRNAs has been a focus of intensive studies with regard to their significance on gene regulation and various aspects of cell biology. In this study, we investigated hypoxia-induced alterations in microRNAs in oral squamous cell carcinoma (OSCC) cells and discussed consequential gene modulation and relevant cellular responses.

Malignant tumor cells outgrow new blood vessel formation and tend to be in hypoxic state. Hypoxic cancer cells adapt to hypoxic conditions by transforming its characteristics. On the other hand, one of the most important features of cancer cells is that carcinoma cells loses its inherent epithelial phenotype and acquires mesenchymal characteristics, called as epithelial-mesenchymal transition(EMT). It has been already well known that EMT contributes to tumor invasion and metastasis. The present study investigated whether hypoxia play a major role in induction of phenotypic changes of oral squamous cell carcinoma(OSCC). Furthermore, the mechanism of EMT in oral squamous cell carcinoma cells by hypoxia has been clarified. To mimic hypoxic condition, cobalt chloride and desferoxamine, well-known hypoxic mimetic agents, were used. This study shows that hypoxia suppresses the expression of E-cadherin(epithelial marker) and increases vimentin and N-cadherin( mesenchymal markers) in OSCC. In addition, α5 integrin protein, which is a receptor for fibronectin and an important molecule for tumor invasion, is prominently induced by hypoxia.

The mechanisms underlying the actions of the antioxidants upon reactive oxygen species (ROS) generation by NADPH oxidase complex have remained uncertain. In this study, we investigated NADPH oxidase activity and the role of antioxidant enzymes upon the generation of ROS during hypoxic stress. ROS generation was found to increase in the mouse kidney under hypoxic stress in a time-dependent manner. Moreover, we found in MCT cells that hypoxia-induced hydrogen peroxide production was decreased by NAC pretreatment. We further analyzed HIF-1α, PHD2 and VHL expression in the NAC-pretreated MCT cells and assessed the response of antioxidant enzymes at the transcriptional and translational levels. SOD3 and Prdx2 were significantly increased during hypoxia in the mouse kidney. We also confirmed in hypoxic Prdx2-l- and SOD3 transgenic mice that erythropoietin (EPO) is transcriptionally regulated by HIF-1α. In addition, although EPO protein was found to be expressed in a HIF-1α independent manner in three mouse lines, its activity differed markedly between normal and Prdx2-l-/SOD3 transgenic mice during hypoxic stress. In conclusion, our current results indicate that NADPH oxidase-mediated ROS generation is associated with hypoxic stress in the mouse kidney and that SOD3 and Prdx2 cooperate to regulate cellular redox reactions during hypoxia.

Tumor cells under hypoxic conditions are often found due to the rapid outgrowth of their vascular supply, and,in order to survive hypoxia, these cells induce numerous signaling factors. Erk is an important kinase in cell survival, and its activity is regulated by Raf kinases through numerous growth factor receptors. The authors investigated Erk activation and Raf/Erk signaling using the hypoxia-mimetic agent, cobalt chloride (CoCl2), in oral squamous cell carcinoma (OSCC) cells. CoCl2 increases Erk phosphorylation in both a dose- and time-dependent manner. In addition, blocking the activation of epidermal growth factor receptor (EGFR) using PD168393 abolished Erk activation in response to CoCl2, suggesting that Erk phosphorylation by CoCl2 is dependent on EGFR.

Transcriptional control plays an important role in regulating submergence responses in plants. Although numerous genes are highly induced during hypoxia, their individual roles in hypoxic responses are still poorly understood. Through microarray studies, we identified a number of transcription factors (TF) that are induced in different stages of hypoxia. We have chosen two TFs, AtHRE1, which was specifically induced during hypoxia but not by cold, drought or dehydration, and WRKY22, which was rapidly and strongly induced upon submergence in Arabidopsis, for further studies. Our results suggest that in addition to ethylene an ethylene-independent signal is also required to mediate hypoxia induction of HRE1. Through a series of genetic and molecular analyses, we found that hypoxia-inducible genes could be affected by AtHRE1-RNAi lines in two different ways: hypoxic induction of glycolytic and fermentative genes was reduced, whereas induction of a number of peroxidase and cytochrome P450 genes was increased. Taken together, our results show that AtERF73/HRE1 is involved in modulating ethylene responses under both normoxia and hypoxia. We found that many genes in the WRKY transcription factor (TF) family were rapidly and strongly induced upon submergence in Arabidopsis. Notably, a large proportion of innate immunity marker genes were co-induced with WRKYs under submergence and other stresses. Compared to wild-type, WRKY22 T-DNA insertion mutants, wrky22-ko1 and wrky22-ko2, have lower submergence-acclimatized disease resistance. Submergence induction of innate immunity markers, such as FRK1 and WRKY53, were lower in these WRKY22 mutants. These results provide evidence that submergence triggers Arabidopsis immunity through WRKY22, allowing plants to defend simultaneous or sequential infection upon floods.

본 연구에서는 맥류 습해의 원인인 과습에 의한 근권의 산소부족이 맥류 뿌리의 생장 및 혐기 발효대사 효소(alcohol dehydrogenase, ADH; lactate dehydrogenase, LDH)에 미치는 영향을 조사하였다. 양액재배를 이용하여 1.5엽기 맥류 유묘에 용존산소 1.5-2 ppm 정도의 혐기처리를 1, 3, 5, 7일간 실시하였다. 혐기조건에서 뿌리의 생장은 모든 맥종에서 감소하였으며, 감소정도는 내습성이 낮은 보리가 내습성이 높은 밀과 호밀보다 낮았다. 정상조건에서 ADH 활성은 보리가 LDH 활성은 호밀이 가장 높았으나 두 효소 모두 맥종 간의 차이는 크지 않았다. 혐기처리에 의해 ADH와 LDH 활성은 모든 맥종에서 공통적으로 증가하였으며 증가 정도는 호밀과 밀에서 가장 높았고 보리에서 가장 낮았다. 혐기조건에서 이들 효소의 활성증가는 모든 맥종에서 유사하게 항시발현 동위효소의 증가 및 새로운 동위효소의 발현유도에 의해 나타났다. 혐기조건에서 ADH와 LDH 활성 증가 정도는 맥종의 재해저항성과 정의 상관관계가 인정되었다. 이러한 결과는 맥류의 내습성에 혐기 발효계 효소가 관여하고 있음을 의미하는 것으로 판단된다.

본 연구에서는 보리 습해의 원인인 과습에 의한 근권의 산소부족이 보리의 뿌리와 지상부의 amylase 및 sucrose synthase활성에 미치는 영향을 배양액의 용존산소를 1~~2ppm 의 혐기조건으로 1-7일간 처리한 3엽기 보리 유묘를 이용하여 조사하였다. 해당과정의 재료인 glucose의 공급에 관여하는 효소 중에서 전분을 분해하는 α-amylas 의 활성은 혐기조건에서 증가하나 자당을 분해하는 sucrose synthase활성은 혐기조건에서도 호기적 상태의 수준을 유지하였다. 이러한 결과는 에너지 획득과정에서의 α-amylas 의 역할이 호기조건에서보다 혐기조건에서 상대적으로 증대하는 것을 의미하는 것으로 사료된다.

유묘기 보리 습해의 주요 원인은 과습에 의한 근권의 산소 부족이다 따라서 혐기조건에 대한 뿌리와 지상부의 생육 및 혐기적 해당발효 효소 활성의 양적 및 질적 반응을 양액재배를 이용하여 용존산소 1ppm 수준의 혐기조건을 1-7일간 처리한 3엽기 보리 유묘를 재료로 이용하여 분석하였다 보리생육 및 통기조직의 발달은 단기적 혐기조건에 의해 크게 영향을 받지 않았다. 반면 뿌리의 ADH와 LDH의 활성이 현저히 증가하였다. 효소활성 수준의 현저한 증가는 모든 동위효소의 발현 증가에 의해 나타났다. 그러나 지상부의 효소활성과 동위효소 발현 양상은 혐기처리에 의해 변화하지 않았다 이러한 결과는 혐기조건 초기에는 산소부족 조건에서 세포의 pH변화를 안정시키면서 혐기적 해당과정을 통한 에너지 획득 효율을 증가시키기 위할 반응이 우선적으로 급속히 진행되는 것으로 해석된다. 이상의 결과는 보리의 내습성 정도와 혐기적 해당과정의 능력과의 관계에 대한 보다 자세한 연구의 필요성을 제시하는 한편, 내습성 품종 육성효율을 증진시키는데 필요한 내습성 간편검정법 개발에 유용한 정보로 활용될 수 있으리라 생각된다