• Title, Summary, Keyword: mitochondrion

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Metformin Inhibits Growth of Hepatocellular Carcinoma Cells by Inducing Apoptosis Via Mitochondrion-mediated Pathway

  • Xiong, Yu;Lu, Qing-Jun;Zhao, Jing;Wu, Guo-Yang
    • Asian Pacific Journal of Cancer Prevention
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    • v.13 no.7
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    • pp.3275-3279
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    • 2012
  • Recently, population-based studies of type 2 diabetes patients have provided evidence that metformin treatment is associated with a reduced cancer incidence and mortality, but its mode of action remains unclear. Here we report effects of metformin on hepatocellular carcinoma (HCC) Hep-G2 cells and details of molecular mechanisms of metformin activity. Our research indicates that metformin displays anticancer activity against HCC through inhibition of the mTOR translational pathway in an AMPK-independent manner, leading to G1 arrest in the cell-cycle and subsequent cell apoptosis through the mitochondrion-dependent pathway. Furthermore, we showed that metformin strongly attenuated colony formation and dramatically inhibited Hep-G2 tumor growth in vivo. In conclusion, our studies suggested that metformin might have potential as a cytotoxic drug in the prevention and treatment of HCC.

Telomere-Mitochondrion Links Contribute to Induction of Senescence in MCF-7 Cells after Carbon-Ion Irradiation

  • Miao, Guo-Ying;Zhou, Xin;Zhang, Xin;Xie, Yi;Sun, Chao;Liu, Yang;Gan, Lu;Zhang, Hong
    • Asian Pacific Journal of Cancer Prevention
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    • v.17 no.4
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    • pp.1993-1998
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    • 2016
  • The effects of carbon-ion irradiation on cancer cell telomere function have not been comprehensively studied. In our previous report cancer cells with telomere dysfunction were more sensitive to carbon-ion irradiation, but the underlying mechanisms remained unclear. Here we found that telomerase activity was suppressed by carbon-ion irradiation via hTERT down-regulation. Inhibition of telomere activity by MST-312 further increased cancer cell radiosensitivity to carbon-ion radiation. hTERT suppression caused by either carbon-ion irradiation or MST-312 impaired mitochondrial function, as indicated by decreased membrane potential, mtDNA copy number, mitochondrial mass, total ATP levels and elevated reactive oxygen species (ROS). PGC-$1{\alpha}$ expression was repressed after carbion-ion irradiation, and hTERT inhibition by MST-312 could further exacerbate this effect. Lowering the mitochondrial ROS level by MitoTEMPO could partially counteract the induction of cellular senescence induced by carbon-ion radiation and MST-312 incubation. Taken together, the current data suggest that telomere-mitochondrion links play a role in the induction of senescence in MCF-7 cells after carbon-ion irradiation.

Ultrastructure of Spermatozoa in Pungtungia herzi (돌고기, Pungtungia herzi 정자의 미세구조)

  • 이영환;김구환
    • Development and Reproduction
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    • v.2 no.2
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    • pp.141-148
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    • 1998
  • The fine structure of spermatozoa of Pungtungia herzi was examined with scanning and transmission electron microscopies. The spermatozoa of p. herzi are approximately 37.4 ${\mu}{\textrm}{m}$ in length and a relatively simple cell with a spherical nucleus, a short midpiece and a tail. The acrosome is not present as in most teleost fishes. The ultrastructure of spermatozoa represents typical characteristics of cyprinid spermatozoa including the lateral insertion of flagellum, the organization of centriolar complex in shallow nuclear fossa, and the occurrence and asymmetrical arrangement of mitochondria. In the nuclear envelope and mitochondrion, however there were some morphological differences for their ultrastructure. The nuclear envelope is severely undulated and the shallow nuclear fossa contains two centrioles which are at the angle of some 130$^{\circ}$ each other. The most significant feature can be observed with the mitochondrion; five or more mitochondria, which are shown in primary spermatocyte, fuse to form a single one in the mature spermatozoon. The mitochondrial aspect is different from that of other cyprinid spermatozoa, where their mitochondria have a conventional aspect and never fuse to form a mitochondrial derivative. In terms of sperm evolution the fused mitochondria are regarded as the apomorphic character in comparison with the separate mitochondria. The single mitochondrion is not reported in cyprinid spermatozoon except the case of Rhodeus.

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Ultrastructure of Spermatozoa of a Korean Bitterling, Acheilognathus koreensis (Pisces, Cyprinidae) (한국산 잉어과어류 칼납자루(Acheilognathus koreensis) 정자의 미세구조)

  • Kim, Kgu-Hwan;Kim, Jeong-Ki;Hwang, Ki-Ju
    • Korean Journal of Ichthyology
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    • v.19 no.4
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    • pp.286-291
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    • 2007
  • The bitterling, Acheilognathus koreensis spermatozoon has been examined by electron microscopy. The epididymal spermatozoa of A. koreensis are representing typical characteristic of cyprinid spermatozoa including the lateral insertion of flagellum, the organization of centriolar complex in shallow nuclear fossa and the asymmetrical arrangement of mitochondria. The sperm mid-piece contains a large mitochondrion characteristic enclosed by membranous vesicles. The mitochondria aspect is different from that of other cyprinid spermatozoa, which their mitochondria have a conventional aspect and never fuse to form a mitochondrial derivative. In term of sperm evolution, the fused mitochondria are regarded as the apomorphic character in comparison with the separate mitochondria. The single mitochondrion is not found in cyprinid spermatozoon except for Rodeus and Pungtungia.

Analysis of Membrane Integrity and Mitochondrial Activity in Fresh and Cryopreserved Boar Sperm Using Flow Cytometry

  • Park C. S.;Li Z. H.;Sung N. D.;Jin D. I.;Cong P. Q.;Kim E. S.;Song E. S.;Yi Y. J.
    • Reproductive and Developmental Biology
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    • v.29 no.4
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    • pp.253-257
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    • 2005
  • This study was carried out to evaluate the effects of washing medium, breed and washing temperature of fresh and frozen-thawed boar sperm on mitochondrial activity and membrane integrity by flow cytometry. More than $80\%$ of fresh sperm washed with mTLP-PVA medium at $20^{\circ}C$ exhibited an intact membrane and a functional mitochondrion. With frozen-thawed samples, a large number of sperm showed both damaged membrane $(36.4\~46.9\%)$ and nonfunctional mitochondrion $(55.1\~71.1\%)$ in the mTLP-PVA and BTS washing media at $20^{\circ}C$. There were no breed effects of fresh and frozen-thawed sperm on mitochondrial activity and membrane integrity. The percentages of damaged membrane of fresh and frozen sperm, respectively, were higher at $4^{\circ}C$ washing temperature than at $20^{\circ}C$ washing temperature in the mTLP-PVA medium. We found that washing medium and washing temperature of fresh and frozen-thawed boar sperm were important for the analyses of mitochondrial activity and membrane integrity by flow cytometry.

Ultrastructural Observations of a Human Cutaneous Leishmaniasis (인체 피부에 기생한 Leishmania tropica의 전자현미경적 관찰)

  • Seo, Young-Hoon;Hur, Kyu-Chung;Deung, Young-Kun;Kim, Chung-Sook;Lee, Yoo-Bock
    • Applied Microscopy
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    • v.10 no.1_2
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    • pp.27-32
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    • 1980
  • A case of cutaneous leishmaniasis developed in a 48 year old Korean male who returned from middle east was studied by light and electron microscopic observations. Light microscopically, the lesion consisted of heavy chronic ill-defined granulomatous inflammation involving entire thickness of the dermis, composed of mainly histiocytic and small mononuclear cell infiltrations without evidence of necrosis or giant cell formation. Giemsa staining revealed numerous intracellular micro-organisms within histiocytes, showing dark stained central dot surrounded by light stained cytoplasm. Electron microscopically, the organisms were observed mostly ovoid in shape and frequently binary mitotic features within the host cells. follicle consisted of double unit membranes and microtubules, which are immediately below these membrnae. A long kinetoplast was noted within a very elongated mitochondrion at the center of the organisms and a flagella rose in front of the kineoplast but ended within the cytoplasm. Large numbers of free ribosomes, occasional Golgi complex and SER were also noted, but RER was seldom found. These ultrastructural features corresponded to promastigote stage of Leishmania tropica. In principle, leishmaniasis is a tropical disease and can not be found in temperate zone. However, travel to mideast by many Koreans may contract this disease while they are in endemic regions.

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Ultrastructure of the flagellar apparatus in Rhinomonas reticulata var. atrorosea (Cryptophyceae, Cryptophyta)

  • Nam, Seung Won;Go, Donghee;Son, Misun;Shin, Woongghi
    • ALGAE
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    • v.28 no.4
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    • pp.331-341
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    • 2013
  • Rhinomonas reticulata var. atrorosea G. Novarino is a photosynthetic marine flagellate that is known to have typical characteristics of cryptomonads. We examined the flagellar apparatus of R. reticulata var. atrorosea by transmission electron microscopy. The major components of the flagellar apparatus of R. reticulata var. atrorosea consisted of four types of microtubular roots (1r, 2r, 3r, and mr), a non-keeled rhizostyle (Rhs), mitochondrion-associated lamella (ML), two connections between basal bodies, a striated fibrous root (SR) and a striated fiber-associated microtubular root (SRm). Four types of microtubular roots originated near the ventral basal body and extended toward the left side of the basal bodies. The non-keeled Rhs originated at the Rhs-associated striated fiber, which was located between two basal bodies and extended into the middle of the cell. The ML was a plate-like fibrous structure associated with mitochondria and originating from a Rhs-associated fiber. It split into two parts and extended toward the dorsal-posterior of the cell to a mitochondrion. The SR and SRm extended parallel to the anterior lobe of the cell. The overall configuration of the flagellar apparatus in R. reticulata var. atrorosea was similar to the previously reported descriptions of those of Cryptomonas paramecium, C. pyrenoidifera, C. ovata, Hanusia phi, Guillardia theta, and Proteomonas sulcata. However, the flagellar apparatus system of R. reticulata var. atrorosea was more complex than those of other cryptomonad species due to the presence of an additional microtubular root and other distinctive features, such as a rhizostyle-associated striated fiber and large ML.