RESUMO
Induction of mitochondria-controlled (intrinsic) apoptosis is a mainstay of current anti-neoplastic chemotherapies. Activation of this death pathway is counteracted by BCL-2-like proteins, which functionally set the threshold for apoptosis and determine whether malignant cells are sensitive or resistant to anti-cancer treatments. Hence, unlocking the intrinsic apoptotic cascade and promoting the cell's commitment to undergo apoptosis concordantly promotes efficacy of anti-cancer treatments. Here, we show that hyperosmotic stress enforces addiction of colorectal cancer cells to BCL-XL, thereby exhausting the protective capacity of BCL-2-like proteins and priming mitochondria for death. Our work identifies osmotic pressure as a cell extrinsic factor that modulates responsiveness of colorectal cancer cells to therapy.
Assuntos
Neoplasias Colorretais/metabolismo , Pressão Osmótica , Interferência de RNA , Proteína bcl-X/metabolismo , Apoptose/efeitos dos fármacos , Apoptose/genética , Compostos de Bifenilo/farmacologia , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/genética , Neoplasias Colorretais/tratamento farmacológico , Neoplasias Colorretais/genética , Células HCT116 , Células HT29 , Humanos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/genética , Mitocôndrias/metabolismo , Nitrofenóis/farmacologia , Piperazinas/farmacologia , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Sulfonamidas/farmacologia , Proteína Killer-Antagonista Homóloga a bcl-2/genética , Proteína Killer-Antagonista Homóloga a bcl-2/metabolismo , Proteína X Associada a bcl-2/genética , Proteína X Associada a bcl-2/metabolismo , Proteína bcl-X/genéticaRESUMO
The tumor environment critically influences responsiveness of cancer cells to chemotherapies, most of which activate the mitochondria-regulated (intrinsic) apoptotic cascade to kill malignant cells. Especially skin tumors encounter an environment with remarkable biophysical properties. Cutaneous accumulation of Na+ locally establishes osmotic pressure gradients in vivo (hypertonicity or hyperosmotic stress), but whether cutaneous hypertonicity is a factor that modulates the responsiveness of skin cancers to therapeutic apoptosis-induction has thus far not been investigated. Here, we show that hyperosmotic stress lowers the threshold for apoptosis induction in malignant melanoma, the deadliest form of skin cancer. Hypertonic conditions enforce addiction to BCL-2-like proteins to prevent initiation of the mitochondria-regulated (intrinsic) apoptotic pathway. Essentially, hyperosmotic stress primes mitochondria for death. Our work identifies osmotic pressure in the tumor microenvironment as a cell extrinsic factor that modulates responsiveness of malignant melanoma cells to therapy.