chapter 9-cancer Flashcards
what is receptor trysoine kinases?-objective 13
an increase in growth factors
-an example is sending growth signals into the cell even when growth factors are at very low levels
what is autocrine stimulation?
some cancers acquire the ability to secrete their own growth factors
cancer cells must have what to enable them to attain self-sufficiency and proliferate in the absence of external growth signals?-objective 13
mutations
where do the most common mutations conferring resistance to apoptosis occur?-objective 13
p53-tumor suppressing gene
what does angiogenesis do?-objective 13
- angiogenesis recruits new vascular endothelial cells and initiates the proliferation of existing blood vessel cells,allowing small cancer to become large cancers
- if cancers are to grow larger than a millimeter in diameter then they need their own blood supply to deliver oxygen and nutrients
- tiny cancers lack the ability to grow new blood cells and more advanced cancers can secrete multiple factors that stimulate new blood vessel growth, called angiogenesis
- therapies directed against new vessel growth are; bevacizumab, a monoclonal antibody that inhibits VEGF and PDGF receptor tyrosine kinases; and thalidomide which decreases vascular proliferation
discuss the factors implicated in metastasis of tumors: lack of cellular adhesion-objective 13
- cells in the body are not immortal besides germ cells and stem cells, and can divide only a limited number of time before they cease or die
- a block to unlimited cell division is the size of a specialized structure called telomere
- telomeres are protective end or caps on each chromosome and are placed and maintained by a specialized enzyme called telomerase, active only in germ and stem cells, all other cells lack it
- when non-germ cells begin to proliferate abnorally, their telomere caps become smaller and smaller w/each cell division; short telomers normally signal the cell to cease cell division, if they become critically small , the chromosomes become unstageable and fragement, then the cells die
- when they reach a critical age, cancer cells somehow activate telomerase to restore and maintain their telomeres, allowing them to continue to divide
- activated in cancer stem cells and cancer cells it is an attractive therapeutic agent
discuss the factors implicated in metastasis of tumors: absence of cellular barriers- objective 13
look up
what is cancer metabolism?
- cancer cells have different nutritional requirements from non-proliferating cells
- cancers often must grow in a hypoxic and acidic environment
- cancers are also parasites, able to selectively extract nutrients from the bloodstream w/o any evolutionary pressure for balanced nutrition
- in the presence of oxygen, cancer cells can perform glycolysis, not OXPHOS,which allows lactate and its metabolites to be used for the more efficient production of lipids and other molecule building blocks needed for rapid cell growth
what is oncongene addiction?
- cancers that arise b/c of drive mutations depend on mutant genes and proteins for their continued growth and survival
- if mutations and abnormal proteins can be returned to their normal states, the cancers usually stop growing and can regress
- cancers that are addicted to their mutant cancer genes are called oncogene addiction
- treating the addiction treats the cancer q
what is the role of chronic inflammation and the development of cancer cells?-objective 12
- both cancer and inflammation, inflammatory cells, neutorphils, lymphocytes and macrophages migrate to the site of injury and release cytokines and growth and survival factors that stimulate local cell proliferation and new blood vessel growth to promote wound healing by tissue remodeling
- these factors combine in chronic inflammation to promote continued proliferation
- also, inflammatory cells release compounds such as reactive oxygen species (ROS) and other reactive molecules to that can promote mutations and block the cellular response to DNA damage
what is mestasis?
-the spread of cancer cells from the site of original tumor to distant tissues and organs throughout the body
-contributes to the significant pain and suffering of cancer
,and is the major cause of death from cancer
-1st step is local spread, can occur by direct tumor extension
-cells then migrate away from cells and towards surrounding tissues
-to transition from local to distant metastasis, the cancer cells must also be able to invade local blood and lymphatic vessels,
-a successful metastatic cell must be able to survive in the circulation, attach in an appropriate new microenvironment, and multiply to produce an entire new tumor
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can most cells metastes?
no-it is a highly inefficient process
What are the stages of cancer?
- stage 1: cancer confined to the organ of origin
- stage 2: cancer is locally invasive
- stage 3: cancer has spreads to regional structures, ex;lymph nodes
- stage 4: cancer has spread to to distant sites such as liver cancer spreading to lungs
- stage 4:
what are paraneoplastic syndromes?
- symptom complexes that are triggered by a cancer but are not caused by direct local effects of the tumor mass
- they are mostly commonly caused by biologic substances released from the tumor or by an immune response triggered by tumor
- they may be the earliest symptom of an unknown cancer
- ex: hypoglycemia, chusings syndrome, hypercalcemia, carcinod syndrome, dermatomyositis, anemia, venous thrombosis
what is the most frequent reported symptom of cancer?
fatigue
