Sporadic Breast Cancer
Breast cancer is the most commonly occurring cancer in women. Non-hereditary, sporadic breast cancer is the most widespread, representing 85 to 90% of all cases. Despite its occurrence, it remains the least well-known type. Researchers at CNRS and CEA, working with a team from HĂ´pital Saint-Louis in France, have just discovered the cause of 50% of sporadic breast cancers.
More than four out of five breast cancers are not related to hereditary factors. The sporadic cases are due to causes which were, until recently, poorly understood. On the other hand, hereditary forms of cancer, which represent only 10 to 15% of breast cancers, have for years been the subjects of studies, work which has resulted in the identification of ten genes whose mutation increases the risk of cancer in an individual.
Among these genes, nine are involved in the DNA damage response system, which is the collection of cell mechanisms that optimize the repair of DNA. The tenth gene codes for a protein which inhibits the action of the AKT1 enzyme. And among these ten genes, two are responsible for 50% of hereditary breast cancers: BRCA1 and BRCA2. Researchers from the "Radiobiologie moléculaire et cellulaire" (CNRS / CEA) lab took these data on hereditary cancers as the starting point for their research into non-hereditary forms.
Researchers have been trying to prove whether or not there is a link between hereditary and sporadic cancers. They found that AKT1 protein is over-expressed in 50% of sporadic breast cancers. They were able to show that activation of AKT1 leads to the sequestration of the BRCA1 protein in the cytoplasm. This makes it impossible for the protein to penetrate the nucleus, which prevents it from fulfilling its role in DNA repair. The cell then behaves as if it had no BRCA1 gene, without involving a mutation (unlike hereditary forms, where the BRCA1 gene undergoes an alteration). This phenomenon is observed in 50% of sporadic tumors. These results show a single, previously undetected, link between sporadic and hereditary cancers: the DNA damage response system.
http://www.sciencedaily.com/releases/2008/11/081121081059.htm
More than four out of five breast cancers are not related to hereditary factors. The sporadic cases are due to causes which were, until recently, poorly understood. On the other hand, hereditary forms of cancer, which represent only 10 to 15% of breast cancers, have for years been the subjects of studies, work which has resulted in the identification of ten genes whose mutation increases the risk of cancer in an individual.
Among these genes, nine are involved in the DNA damage response system, which is the collection of cell mechanisms that optimize the repair of DNA. The tenth gene codes for a protein which inhibits the action of the AKT1 enzyme. And among these ten genes, two are responsible for 50% of hereditary breast cancers: BRCA1 and BRCA2. Researchers from the "Radiobiologie moléculaire et cellulaire" (CNRS / CEA) lab took these data on hereditary cancers as the starting point for their research into non-hereditary forms.
Researchers have been trying to prove whether or not there is a link between hereditary and sporadic cancers. They found that AKT1 protein is over-expressed in 50% of sporadic breast cancers. They were able to show that activation of AKT1 leads to the sequestration of the BRCA1 protein in the cytoplasm. This makes it impossible for the protein to penetrate the nucleus, which prevents it from fulfilling its role in DNA repair. The cell then behaves as if it had no BRCA1 gene, without involving a mutation (unlike hereditary forms, where the BRCA1 gene undergoes an alteration). This phenomenon is observed in 50% of sporadic tumors. These results show a single, previously undetected, link between sporadic and hereditary cancers: the DNA damage response system.
http://www.sciencedaily.com/releases/2008/11/081121081059.htm
posted by Amber Thrapp at 7:54 PM
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