Apoptosis - Wikipedia, the free encyclopedia. Apoptosis (from Ancient Greek . These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, chromosomal DNA fragmentation, and global m. RNA decay. Between 5. For example, the separation of fingers and toes in a developing human embryo occurs because cells between the digits undergo apoptosis. Unlike necrosis, apoptosis produces cell fragments called apoptotic bodies that phagocytic cells are able to engulf and quickly remove before the contents of the cell can spill out onto surrounding cells and cause damage.
Apoptosis can be initiated through one of two pathways. In the intrinsic pathway the cell kills itself because it senses cell stress, while in the extrinsic pathway the cell kills itself because of signals from other cells. Both pathways induce cell death by activating caspases, which are proteases, or enzymes that degrade proteins. The two pathways both activate initiator caspases, which then activate executioner caspases, which then kill the cell by degrading proteins indiscriminately. Research on apoptosis has increased substantially since the early 1. In addition to its importance as a biological phenomenon, defective apoptotic processes have been implicated in a wide variety of diseases. Excessive apoptosis causes atrophy, whereas an insufficient amount results in uncontrolled cell proliferation, such as cancer.
Some factors like Fas receptors and caspases promote apoptosis, while some members of the Bcl- 2 family of proteins inhibit apoptosis. Discovery and etymology. In 1. 88. 5, anatomist Walther Flemming delivered a more precise description of the process of programmed cell death. However, it was not until 1.
While studying tissues using electron microscopy, John Foxton Ross Kerr at University of Queensland was able to distinguish apoptosis from traumatic cell death. In 1. 97. 2, the trio published a seminal article in the British Journal of Cancer. Kerr, Wyllie and Currie credited James Cormack, a professor of Greek language at University of Aberdeen, with suggesting the term apoptosis.
Apoptosis: Death comes for the Cell Joe W. Ramos [email protected] From Ingmar Bergman’s The Seventh Seal. Cell Death or Apoptosis biology Animation. Video Lectures, Video Courses. Download the free Adobe Flash Player to view this animation. The morphological process resulting in programmed cell death is called apoptosis. Apoptosis & Caspase 8, The Proteolysis Map—animation; Apoptosis & Caspase 7, The Proteolysis Map—animation; Apoptosis MiniCOPE Dictionary—list of apoptosis terms and acronyms; Apoptosis (Programmed Cell Death).
Kerr received the Paul Ehrlich and Ludwig Darmstaedter Prize on March 1. He shared the prize with Boston biologist H. What transformed cell death from obscurity to a major field of research were two things: the identification of components of the cell death control and effector mechanisms, and the linkage of abnormalities in cell death to human disease, in particular cancer. The 2. 00. 2 Nobel Prize in Medicine was awarded to Sydney Brenner, Horvitz and John E.
You have free access to this content Apoptosis. Apoptosis, derived from the. Free article library for medical students, biology students, junior doctors and health care professionals. Apoptosis, also known as programmed cell death (PCD), is a genetically programmed event in animal cells. Apoptosis Sherwin Wilk, Ph.D. Mount Sinai School of Medicine Department of Pharmacology and Biological Chemistry Cell Signaling Systems Course Spring 2005 – A free PowerPoint PPT presentation (displayed as a Flash slide.
Sulston for their work identifying genes that control apoptosis. The genes were identified by studies in the nematode C. Sulston won the Nobel Prize in Medicine in 2.
In Greek, apoptosis translates to the . Cormack, professor of Greek language, reintroduced the term for medical use as it had a medical meaning for the Greeks over two thousand years before. Hippocrates used the term to mean . Galen extended its meaning to .
Cormack was no doubt aware of this usage when he suggested the name. Debate continues over the correct pronunciation, with opinion divided between a pronunciation with the second p silent (ap- . To show the derivation clearly, we propose that the stress should be on the penultimate syllable, the second half of the word being pronounced like . The two best- understood activation mechanisms are the intrinsic pathway (also called the mitochondrial pathway) and the extrinsic pathway.
The intrinsic pathway is activated by intracellular signals generated when cells are stressed and depends on the release of proteins from the intermembrane space of mitochondria. The extrinsic pathway is activated by extracellular ligands binding to cell- surface death receptors, which leads to the formation of the death- inducing signaling complex (DISC). A cell initiates intracellular apoptotic signaling in response to a stress, which may bring about cell suicide. The binding of nuclear receptors by glucocorticoids. A number of cellular components, such as poly ADP ribose polymerase, may also help regulate apoptosis.
This step allows those signals to cause cell death, or the process to be stopped, should the cell no longer need to die. Several proteins are involved, but two main methods of regulation have been identified: the targeting of mitochondria functionality. An extrinsic pathway for initiation identified in several toxin studies is an increase in calcium concentration within a cell caused by drug activity, which also can cause apoptosis via a calcium binding protease calpain. Intrinsic pathway.
Without them, a cell ceases to respire aerobically and quickly dies. This fact forms the basis for some apoptotic pathways. Apoptotic proteins that target mitochondria affect them in different ways. They may cause mitochondrial swelling through the formation of membrane pores, or they may increase the permeability of the mitochondrial membrane and cause apoptotic effectors to leak out. SMAC binds to proteins that inhibit apoptosis (IAPs) thereby deactivating them, and preventing the IAPs from arresting the process and therefore allowing apoptosis to proceed. IAP also normally suppresses the activity of a group of cysteine proteases called caspases. Therefore, the actual degradation enzymes can be seen to be indirectly regulated by mitochondrial permeability.
Cytochrome c is also released from mitochondria due to formation of a channel, the mitochondrial apoptosis- induced channel (MAC), in the outer mitochondrial membrane. The apoptosome cleaves the pro- caspase to its active form of caspase- 9, which in turn activates the effector caspase- 3. MAC (not to be confused with the Membrane Attack Complex formed by complement activation, also commonly denoted as MAC), also called .
Bax and/or Bak form the pore, while Bcl- 2, Bcl- x. L or Mcl- 1 inhibit its formation. Extrinsic pathway. Most cells in the human body have two receptors for TNF- alpha: TNFR1 and TNFR2. The binding of TNF- alpha to TNFR1 has been shown to initiate the pathway that leads to caspase activation via the intermediate membrane proteins TNF receptor- associated death domain (TRADD) and Fas- associated death domain protein (FADD).
FLIP inhibits the activation of caspase- 8. In some types of cells (type I), processed caspase- 8 directly activates other members of the caspase family, and triggers the execution of apoptosis of the cell. In other types of cells (type II), the Fas- DISC starts a feedback loop that spirals into increasing release of proapoptotic factors from mitochondria and the amplified activation of caspase- 8.
This balance is the proportion of proapoptotic homodimers that form in the outer- membrane of the mitochondrion. The proapoptotic homodimers are required to make the mitochondrial membrane permeable for the release of caspase activators such as cytochrome c and SMAC. Control of proapoptotic proteins under normal cell conditions of nonapoptotic cells is incompletely understood, but in general, Bax or Bak are activated by the activation of BH3- only proteins, part of the Bcl- 2 family. Caspases. Caspases play the central role in the transduction of ER apoptotic signals. Caspases are proteins that are highly conserved, cysteine- dependent aspartate- specific proteases. There are two types of caspases: initiator caspases, caspase 2,8,9,1. The activation of initiator caspases requires binding to specific oligomeric activator protein.
Effector caspases are then activated by these active initiator caspases through proteolytic cleavage. The active effector caspases then proteolytically degrade a host of intracellular proteins to carry out the cell death program. Caspase- independent apoptotic pathway There also exists a caspase- independent apoptotic pathway that is mediated by AIF (apoptosis- inducing factor).
In fact, iodine and thyroxine also stimulate the spectacular apoptosis of the cells of the larval gills, tail and fins in amphibians metamorphosis, and stimulate the evolution of their nervous system transforming the aquatic, vegetarian tadpole into the terrestrial, carnivorous frog. After a cell receives stimulus, it undergoes organized degradation of cellular organelles by activated proteolytic caspases. In addition to the destruction of cellular organelles, m. RNA is rapidly and globally degraded by a mechanism that is not yet fully characterized. A cell undergoing apoptosis shows a characteristic morphology: Cell shrinkage and rounding are shown because of the breakdown of the proteinaceous cytoskeleton by caspases. The nucleus breaks into several discrete chromatin bodies or nucleosomal units due to the degradation of DNA.
During karyorrhexis, endonuclease activation leaves short DNA fragments, regularly spaced in size. These give a characteristic . Tests for DNA laddering differentiate apoptosis from ischemic or toxic cell death. Several caspases, in addition to APAF- 1 and FADD, have been mutated to determine the new phenotype. In order to create a tumor necrosis factor (TNF) knockout, an exon containing the nucleotides 3. This exon encodes a portion of the mature TNF domain, as well as the leader sequence, which is a highly conserved region necessary for proper intracellular processing. TNF- /- mice develop normally and have no gross structural or morphological abnormalities.
However, upon immunization with SRBC (sheep red blood cells), these mice demonstrated a deficiency in the maturation of an antibody response; they were able to generate normal levels of Ig. M, but could not develop specific Ig. G levels. Apaf- 1 is the protein that turns on caspase 9 by cleavage to begin the caspase cascade that leads to apoptosis. Since a - /- mutation in the APAF- 1 gene is embryonic lethal, a gene trap strategy was used in order to generate an APAF- 1 - /- mouse.
This assay is used to disrupt gene function by creating an intragenic gene fusion.
Apoptosis and Cancer . Apoptosis is the mechanism responsible for the physiological deletion of cells and appears to be intrinsically programmed. It is characterized by distinctive morphologic changes in the nucleus and cytoplasm, chromatin cleavage at regularly spaced sites, and the endonucleolytic cleavage of genomic DNA; ( DNA FRAGMENTATION); at internucleosomal sites. This mode of cell death serves as a balance to mitosis in regulating the size of animal tissues and in mediating pathologic processes associated with tumor growth. Loss of apoptosis is one of the key mechanisms behind cancer..
Mar- Apr; 2. 1(2): 4. The aim of this study was the investigation of cytotoxic properties of these complexes against a panel of human tumor cell lines, with elucidation of their anticancer mechanisms in He. La cells. METHODS: Characterization of anticancer activity of the investigated ruthenium complexes 1 and 2 included analysis of cytotoxicity by MTT assay. Cell cycle phase disruption of He.
La cells treated with complexes 1 and 2 was analyzed by flow cytometry after propidium iodide (PI) staining. Annexin V- FITC/PI double staining and further flow cytometry analysis and acridine orange (AO)/ethidium bromide (EB) double staining and fluorescent microscopy were used to determine the apoptotic potential of the investigated ruthenium complexes. The inhibitory effect on gelatinases (MMP- 2 and MMP- 9) as an indication of possible antimetastatic potential was also analyzed using gelatine zymography. RESULTS: The 5. 0% cell growth inhibition (IC5. Both complexes induced G2 phase cell cycle arrest and apoptosis in He.
La cells. Inhibitory effect of complex 2 on MMP- 2 activity was detected. CONCLUSIONS: This work revealed the potential of the investigated Ru(II)- DMSO- chalcone complexes as anticancer agents with cytotoxic and pro- apoptotic activity and indicated complex 2 as leading compound for further chemical modifications and anticancer research. In the present study, we evaluated the anti- proliferative and the pro- apoptotic abilities of ABL alone or in combination with gemcitabine in human NSCLC cell line. A5. 49 cells were treated, in vitro, with ABL, gemcitabine, and the combination of ABL and gemcitabine for 7. Our results showed ABL and gemcitabine inhibited cell growth and induced apoptosis of A5. These effects after the combination of ABL and gemcitabine were superior to those of each alone. Furthermore, signal transduction analysis revealed NF- .
Our findings suggest that ABL combined with gemcitabine elicits a potent apoptosis of lung cancer cell and hence ABL has the potential to be developed as a chemotherapeutic agent. Evaluating chemotherapy response is essential to predict survival rate and guide future chemotherapy. Until now, the evaluation of pathological response mainly involves quantitative assessment and is often inconsistent with clinical response.
We explored the evaluation of pathological responses by both quantitative and qualitative methods, i. Biopsy and resection specimens were compared to evaluate reduction in cellularity, which were subsequently categorized into stages of Miller- Payne (MP) classification. The resection specimens were stained with TUNEL and the percentage of apoptosis was calculated. Reduction in cellularity between biopsy and mastectomy specimens with TUNEL staining is evaluated as a modification of the MP method. RESULTS: We found no association between clinical responses with percentage of apoptosis, MP pathological responses and modified MP.
There was a correlation between the dead cell evaluated by MP and by modified MP (p=0. CONCLUSION: Modified MP increases the degree or grading of pathological responses, but it does not improve the correlation with clinical response. Jan- Feb; 2. 1(1): 1.
Phase- contrast and confocal fluorescence microscopies were used to assess the morphological changes that occured in these cells following myricetin treatment. Flow cytometry using propidium iodide (PI) and Annexin- V FITC as probes was employed to evaluate the effects on cell cycle arrest and apoptosis induction, respectively. The effect of myricetin on intracellular ROS production was measured by flow cytometry with a fluorescent probe CM- DCFH2- DA. RESULTS: Myricetin induced a dose- dependent as well as time- dependent growth inhibitory effect in U2. Myricetin treatment resulted in U2.
Detached cells had irregular shape and incapable to maintain their membranes intact. Apoptotic cell death was induced by myricetin treatment as witnessed by fluorescence microscopy. The percentage of early and late apoptotic cells increased from 0. We also observed a dose- dependent increase in Bax and Bad levels and a dose- dependent decrease in Bcl- 2 and Bcl- xl expression levels following myricetin treatment.
Cell cycle arrest in G2/M phase of the cell cycle was also induced by the drug treatment. A concentration- dependent ROS generation was also witnessed and a 3- fold increase of ROS production was seen after 6. Jan- Feb; 2. 1(1): 8. Furthermore, attempts were made to explore the signaling mechanism which may be responsible for its effect. METHODS: Cell growth inhibition was assessed by MTT and LDH assays.
Flow cytometric analysis was performed to determine cell arrest in the cell cycle phase and apoptosis. Furthermore, to confirm the apoptotic activity of arctigenin, caspase- 9 and - 3 activities analysis was performed. The levels of reactive oxygen species (ROS) and p.
MAPK) were investigated to determine their role in inducing apoptosis in arctigenin- treated HT- 2. RESULTS: MTT and LDH results demonstrated significant cell growth inhibitory effect of arctigenin on HT- 2. Furthermore, increase in cell number arrested at G2/M phase was observed in flow cytometric analysis upon arctigenin treatment. In addition, arctigenin increased the apoptotic ratio in a dose- dependent manner. The involvement of intrinsic apoptotic pathway was indicated by the activation of caspase- 9 and - 3. Moreover, increased ROS production, activation of p. MAPK and changes in mitochondrial membrane potential (.
The Ec- 1. 09 cells were cultured in vitro with different concentrations of tanshinone IIA (2 . MTT assay was used to evaluate the proliferative inhibition rate of tanshinone IIA on esophageal Ec- 1. After 2. 4 hours of culturing in vitro, a control group was assigned. The apoptosis rate was detected by the AO/EB and annexin V- FITC/propidium iodide assay, and the protein levels of Caspase- 4 and CHOP were determined by the Western blot technique.
MTT data showed that tanshinone IIA could significantly inhibit the proliferation of Ec- 1. Compared with the control group, tanshinone IIA could apparently induce apoptosis of Ec- 1. Caspase- 4 and CHOP (p < 0. Tanshinone IIA can significantly induce the apoptosis of Ec- 1. The optical density at 4. QBC9. 39 cells was measured by CCK8 assay and its growth inhibition ratio was calculated. Flow cytometry and transwell migration assay were applied to detect cell apoptosis and invasion respectively.
RT- PCR and immunocytochemistry analyses were used to detect expressions of vascular endothelial growth factor- C (VEGF- C), cyclooxygenase- 2 (COX- 2), and proliferating cell nuclear antigen (PCNA). Enzyme- linked immunosorbent assay (ELISA) was carried out to examine the secretion of VEGF- C and COX- 2 in QBC9. RESULTS: Exposure to HPD- PDT can significantly suppress the growth of QBC9. P< 0. 0. 5). HPD- PDT can promote apoptosis of QBC9. When the concentration of HPD was 2 . The HPD- PDT can reduce the m.
RNA and protein expressions of VEGF- C, COX- 2, and PCNA, and decrease the secretion of VEGF- C and COX- 2 in QBC9. CONCLUSION: PDT could promote apoptosis and inhibit growth and invasion of cholangiocarcinoma cells QBC9. Autophage, cell death and mdr. RESULTS: IC5. 0 value of ADR in Lo. Vo/Adr was significantly decreased in response to RAPA (P < 0. Autophagy rate of Lo. Vo/Adr cells was higher in the ADR or RAPA- alone group than in control (p < 0.
ADR/RAPA combination has significantly increased autophagy rate compared to ADR or RAPA alone (p < 0. Compared with controls, apoptosis rate in the RAPA group had no difference (p > 0. ADR group (p < 0. Furthermore, apoptosis rate was significantly different in combined RAPA/ADR compared to ADR (p < 0. Expression of m. RNA and protein P- gp level of mdr 1 gene in Lo. Vo/Adr cells were significantly decreased under RAPA- treated groups at 2.
The underlying mechanisms that regulate TRAIL sensitivity in NSCLC cells are not well understood. The objective of this study was to investigate molecular regulators of the TRAIL pathway in NSCLC cells.
METHODS: The TRAIL- sensitive NSCLC cell line NCI- H3. TRAIL- resistant cell line A5. TRAIL for 2. 4 hours. Then cell viability were measured by MTT assay, meanwhile cell cycle and apoptosis were measured by flow cytometry. Furthermore, mass spectrometry (LC- MS/MS) was used to identify the difference in the protein expression profiles. Finally, real- time PCR was performed to detect the m. RNA expression of TRAIL receptors and apoptotic related proteins.
RESULTS: These results confirmed that NCI- H3. TRAIL, whereas A5.
Both m. RNA and protein levels of voltage- dependent anion- selective channel proteinl (VDAC1), caspase. CASP9), and cytochrome c.
CYC1) were upregulated in H3. A5. 49 cells, whereas antiapoptotic protein BAG- 2 was downregulated. In addition, TRAIL also causes DR5 low expression in A5. CONCLUSIONS: These results indicate that rmh. TRAIL had different anti- tumor activity in different NSCLC cell lines.
Downregulation of VDAC1, CYC1, CASP9, and upregulation of BAG- 2 might be associated with underlying TRAIL- resistance mechanisms. These findings motivated further studies to explore new therapeutic strategy overcoming TRAIL- resistance of NSCLC cells through modulating dysregulation of the proteins above. A recent study has confirmed that demethylation regulates the TSGs expression and proliferation of various types of cancer cells.