Overview

Lung cancer is a kind of cancer that starts as a growth of cells in the lungs. The lungs are two spongy organs in the chest that control breathing.

Lung cancer is the leading cause of cancer deaths worldwide.

Signs and symptoms

Lung cancer typically doesn’t cause symptoms early on. Symptoms of lung cancer usually happen when the disease is advanced.

Signs and symptoms of lung cancer that happen in and around the lungs may include:

  • A new cough that doesn’t go away.
  • Chest pain.
  • Coughing up blood, even a small amount.
  • Hoarseness.
  • Shortness of breath.
  • Wheezing.

Signs and symptoms that happen when lung cancer spreads to other parts of the body may include:

  • Bone pain.
  • Headache.
  • Losing weight without trying.
  • Loss of appetite.
  • Swelling in the face or neck.

Mitochondria possess their own double-stranded circular genome, encoding 13 genes whose protein products are subunits of the respiratory chain or the oxidative phosphorylation system (OXPHOS). Mitochondrial DNA (mtDNA) is present in high copy numbers (103-104 copies per cell) in virtually all cells. Electron transport and ATP synthesis by oxidative phosphorylation act continuously within a mitochondrion. The electron transport chain (ETC), organized into five separate enzymes (Complexes I-V), resides in the inner mitochondrial membrane and is the common pathway by which electrons, derived from energy rich molecules, flow to oxygen. Complexes I through IV each contain part of the electron transport chain, whereas Complex V catalyzes the synthesis of ATP. The final acceptor of the electrons is oxygen, which is reduced to water by the addition of four electrons.

Mitochondrial DNA is also susceptible to damage by environmental carcinogens, such as smoking. Inequality between the frequency and nature of mtDNA mutations between smoker- and non-smoker lung cancer patients has recently been revealed to expand upon the impact of smoking on lung tumorigenesis. With no associations observed between mtDNA mutations with neither age nor gender, the frequency of mtDNA mutation was significantly higher in non-smokers when compared to smokers. This smoking-independent pathway for acquiring mtDNA mutation gives insight into understanding the mitochondrial genetic alterations of these more common new lung cancer cases being seen in clinical settings. However, the majority of the coding mtDNA mutations identified targeted complex I of the respiratory chain and ectopic expression of these mutations increased cellular proliferation, invasion and ROS production in lung cancer cells in vitro. To support this observation, Complex I (NADH dehydrogenase) activity has been shown to be decreased in cells with high metastatic potential.

Overview

Lung cancer is a kind of cancer that starts as a growth of cells in the lungs. The lungs are two spongy organs in the chest that control breathing.

Lung cancer is the leading cause of cancer deaths worldwide.

Signs and symptoms

Lung cancer typically doesn’t cause symptoms early on. Symptoms of lung cancer usually happen when the disease is advanced.

Signs and symptoms of lung cancer that happen in and around the lungs may include:

  • A new cough that doesn’t go away.
  • Chest pain.
  • Coughing up blood, even a small amount.
  • Hoarseness.
  • Shortness of breath.
  • Wheezing.

Signs and symptoms that happen when lung cancer spreads to other parts of the body may include:

  • Bone pain.
  • Headache.
  • Losing weight without trying.
  • Loss of appetite.
  • Swelling in the face or neck.

Mitochondria possess their own double-stranded circular genome, encoding 13 genes whose protein products are subunits of the respiratory chain or the oxidative phosphorylation system (OXPHOS). Mitochondrial DNA (mtDNA) is present in high copy numbers (103-104 copies per cell) in virtually all cells. Electron transport and ATP synthesis by oxidative phosphorylation act continuously within a mitochondrion. The electron transport chain (ETC), organized into five separate enzymes (Complexes I-V), resides in the inner mitochondrial membrane and is the common pathway by which electrons, derived from energy rich molecules, flow to oxygen. Complexes I through IV each contain part of the electron transport chain, whereas Complex V catalyzes the synthesis of ATP. The final acceptor of the electrons is oxygen, which is reduced to water by the addition of four electrons.

Mitochondrial DNA is also susceptible to damage by environmental carcinogens, such as smoking. Inequality between the frequency and nature of mtDNA mutations between smoker- and non-smoker lung cancer patients has recently been revealed to expand upon the impact of smoking on lung tumorigenesis. With no associations observed between mtDNA mutations with neither age nor gender, the frequency of mtDNA mutation was significantly higher in non-smokers when compared to smokers. This smoking-independent pathway for acquiring mtDNA mutation gives insight into understanding the mitochondrial genetic alterations of these more common new lung cancer cases being seen in clinical settings. However, the majority of the coding mtDNA mutations identified targeted complex I of the respiratory chain and ectopic expression of these mutations increased cellular proliferation, invasion and ROS production in lung cancer cells in vitro. To support this observation, Complex I (NADH dehydrogenase) activity has been shown to be decreased in cells with high metastatic potential.