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Related Concept Videos

Apoptosis01:30

Apoptosis

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Apoptosis is a combination of two Greek words, 'apo' and 'ptosis,' meaning separation and falling off, respectively. Hippocrates used this word to describe gangrene, which was caused due to bandaging of fractured bones. Apoptosis was distinguished from necrosis in 1970 when John Kerr reported observations of morphological changes occurring during apoptosis. During one experiment, he observed that the disruption of blood supply to the liver tissue resulted in a size...
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Caspases01:24

Caspases

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Caspase, a family of cysteine proteases, serve as effectors in apoptosis. The ced3 gene in C.elegans was first identified to be involved in apoptosis. This gene encodes the ced-3 caspase that is similar to the interleukin-1-beta converting enzyme or ICE in mammals. In addition to apoptosis, caspases also function in the inflammatory response. Inflammatory caspases are essential in activating pro-inflammatory cytokines that recruit immune cells and block the replication of pathogens inside...
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The Intrinsic Apoptotic Pathway01:31

The Intrinsic Apoptotic Pathway

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Internal cellular stress, such as cellular injury or hypoxia, triggers intrinsic apoptosis. The B-cell lymphoma 2 (Bcl-2) family of proteins are the primary regulators of the intrinsic apoptotic pathway. For example, during DNA damage, checkpoint proteins, such as Ataxia Telangiectasia Mutated (ATM protein) and Checkpoints Factor-2 (Chk2) proteins, are activated. These proteins phosphorylate p53 which further activates pro-apoptotic proteins, such as Bax, Bak, PUMA, and Noxa, and inhibits...
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The Extrinsic Apoptotic Pathway01:17

The Extrinsic Apoptotic Pathway

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The extrinsic apoptotic pathway is initiated when extracellular death-inducing signals, such as specific cytokines, activate the death receptors expressed on the cell surface. The immune cells involved in this pathway are natural killer cells (NK cells) and cytotoxic T-lymphocytes. NK cells are critical in innate immune response, while cytotoxic T-lymphocytes are associated with adaptive immune response. These cells recognize specific receptors expressed on the altered cells and activate...
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Phagocytosis of Apoptotic Cells01:17

Phagocytosis of Apoptotic Cells

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Cells undergoing apoptosis form apoptotic bodies that must be removed immediately to prevent inflammation, autoimmune diseases, and necrosis. Phagocytosis is carried out by professional phagocytes such as macrophages or  immature dendritic cells. Non-professional phagocytes such as  epithelial cells and fibroblasts also take part in this process; however, they are not as effective as professional phagocytes. 
Normal cells contain receptors that prevent them from being recognized...
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Overview of Cell Death01:30

Overview of Cell Death

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Cell death is an essential process where the body gets rid of old or damaged cells. Cell proliferation and death need to be balanced, as an imbalance between the two may lead to cancer or autoimmune diseases.
Cell death was observed in the early 19th century, but there was no experimental evidence to prove it. In 1842, Carl Vogt first discovered cell death in a metamorphic toad; however, it was not termed ‘cell death.’ Scientists discovered different cell death pathways only in the...
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Related Experiment Video

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Detection and Isolation of Apoptotic Bodies to High Purity
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Detection and Isolation of Apoptotic Bodies to High Purity

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The case against apoptosis.

G G Steel1

  • 1Radiotherapy Research Unit, Institute of Cancer Research, Sutton, Surrey, UK. ggsteel@icr.ac.uk

Acta Oncologica (Stockholm, Sweden)
|February 16, 2002
PubMed
Summary
This summary is machine-generated.

Apoptosis is not the primary cause of cell death in normal tissues or tumors. Clonogenic cell survival assays are more appropriate than apoptosis assays for evaluating cancer treatment effectiveness.

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Strategies for Tracking Anastasis, A Cell Survival Phenomenon that Reverses Apoptosis
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Area of Science:

  • Oncology
  • Cell Biology
  • Cancer Research

Background:

  • Apoptosis, often termed programmed cell death, is widely studied for its role in cell loss.
  • Its dominance in normal tissues and tumors is frequently overstated.
  • The term 'programmed cell death' is considered unsatisfactory and best avoided.

Purpose of the Study:

  • To re-evaluate the significance of apoptosis in normal tissue and tumor cell loss.
  • To determine the most appropriate methods for assessing tumor response to drug and radiation therapy.
  • To investigate the relationship between apoptosis and cell survival in treated tumor cells.

Main Methods:

  • Review of existing literature comparing apoptosis assays and clonogenic cell survival assays.
  • Analysis of the utility of apoptosis assays in the context of multi-log cell kill required for effective cancer treatment.
  • Examination of studies investigating the causal relationship between apoptosis and cell survival.

Main Results:

  • Apoptosis is not as dominant a factor in cell loss as previously claimed.
  • Apoptosis assays focus on early cell killing (0-90%), while treatment outcomes depend on multi-log cell kill.
  • Clonogenic cell survival assays are more suitable for assessing treatment efficacy.
  • Evidence of apoptosis often appears downstream from the loss of colony-forming ability.
  • Published studies generally show no causal link between apoptosis and cell survival responses in tumors.

Conclusions:

  • Apoptosis plays a less dominant role in tumor and normal tissue cell loss than often assumed.
  • Clonogenic cell survival assays are the appropriate method for evaluating the effectiveness of cancer treatments.
  • The significance of apoptosis in tumor response to therapy warrants re-evaluation, as it may be a downstream event rather than a primary driver of cell death relevant to treatment outcomes.