Role of reactive oxygen species-dependent protein aggregation in metabolic stress-induced necrosis.
Cancer cells in the inner region of avascularized solid tumours experience metabolical stress by hypoxic and glucose depletion (OGD) and are prone to die by necrosis to form a necrotic core, a common feature of solid tumours. Unlike in apoptosis, where the cellular contents remain packed in the apoptotic bodies that are removed by macrophages, necrosis is characterized by cell membrane rupture, and the release of many cellular proteins including tumour promoting cytokine high mobility group box 1 (HMGB1) into the extra-cellular space. Although ROS produced by metabolic stress are known to cause membrane damage leading to the plasma membrane rupture, its molecular mechanism remains unclear. In this study, we show that some cellular proteins including pro-apoptotic molecules p53, caspase-3, and caspase-9 and a pro-autophagic molecule beclin 1 are not released into the extracellular space but rather aggregated in the cytosol during GD-induced necrosis and that the protein aggregation occurs in a ROS-dependent manner. We also found that Snail, the transcription factor that is induced by GD, was not translocated to the nucleus and aggregated in the cytosol. In addition, Snail interference appeared to block metabolic stress-induced protein aggregation, indicating a critical role(s) of Snail in the protein aggregation. These results demonstrate that in metabolically stressed cancer cells, ROS induce a specific set of cellular proteins to form insoluble aggregates that are highly toxic to cells and trigger the necrosis-associated membrane rupture and HMGB1 release to promote tumour progression.
Department of Molecular Biology, College of Natural Sciences, Pusan National University, Pusan 609-735, Korea.
Cho Hee
CH
Kim
Hyun Min
HM
Jeon
Su Yeon
SY
Lee
Eui Kyong
EK
Jeong
Min Kyung
MK
Ju
Bum Joon
BJ
Park
Hye Gyeong
HG
Park
Sung-Chul
SC
Lim
Song Iy
SI
Han
Ho Sung
HS
Kang
D011232:Chemical Precipitation; D003600:Cytosol / Q000378:metabolism; D024243:HMGB1 Protein / Q000378:metabolism / Q000502:physiology; D056945:Hep G2 Cells; D006801:Humans; D009336:Necrosis / Q000209:etiology* / Q000378:metabolism; D009369:Neoplasms / Q000378:metabolism / Q000473:pathology; D011506:Proteins / Q000187:drug effects / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000494:pharmacology*; D000071250:Snail Family Transcription Factors; D013312:Stress, Physiological / Q000187:drug effects / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D056811:Unfolded Protein Response / Q000187:drug effects / Q000502:physiology*
D024243:HMGB1 Protein; D011506:Proteins; D017382:Reactive Oxygen Species; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53