| Sažetak | Tumori predstavljaju masu izmijenjenih stanica koje pokazuju nepravilan i progresivan rast.
Može ih se podijeliti na maligne, odnosno zloćudne (karcinom, sarkom, limfom, leukemija) i
benigne ili dobroćudne (adenomi, papilomi, polipi). Tumorke stanice imaju poremećenu
regulaciju stanične diobe što uzrokuje proliferaciju stanica i rast novotvorevina. Osobine
tumorskih stanica su nekontrolirani rast, rast stanica u više slojeva, abnormalnost jezgre,
nediferenciranost stanica, nepostojanje kontaktne inhibicije. Razvoj malignog tumora,
odnosno karcinogeneza, se može opisati u 4 stadija: inicijacija, promocija, progresija te
metastaziranje. U kontroli staničnog rasta i diobe sudjeluju onkogeni i tumor-supresorski geni,
odnosno protuonkogeni. Onkogeni su geni koji upravljaju kontrolom rasta i diferencijacijom
tumorskih stanica. Protuonkogeni kodiraju produkte koji sputavaju rast i osiguravaju
negativnu regulaciju staničnog ciklusa. U zloćudnim stanicama promijenjen je metabolizam,
što za posljedicu ima razne kvalitativne i kvantitativne razlike prema normalnim stanicama.
Te promjene obuhvaćaju promjene u sintezi DNA i RNA, promjene u metabolizmu proteina,
promjene u disanju i oksidacijskoj fosforilaciji te osiguranju energije i promjene stanične
membrane. |
| Sažetak (engleski) | Tumors represent the mass of modified cells which exhibit irregular and progressive growth.
They can be divided into malignant (cancer, sarcoma, lymphoma, leukemia) and benign
(adenomas, papillomas, polyps). Tumor cells dusplay dysregulation of cell division that
causes cell proliferation and growth of malignancies. The properties of tumor cells are
uncontrolled growth, cell growth in several layers, the core abnormality, lack of cell
differentiation and lack of contact inhibition. The development of malignant tumors can be
described in four stages: initiation, promotion, progression and metastasis. In the control of
cell growth and division are involved oncogenes and tumor-suppressor genes. Oncogenes are
genes which control the growth control and differentiation of tumor cells. Tumor-suppressor
genes encode products which inhibit the growth and ensuring negative regulation of the cell
cycle. In malignant cells, metabolism is altered with results in a variety of qualitative and
quantitative differences compared to normal cells. These include changes in the synthesis of
DNA and RNA, altterations in the protein metabolism, respiration and oxidative
phosphorylation, with decresed energy supply and changes of cell membrane. |
