Lecture 5 2/7/25 Flashcards
What are the characteristics of sustained proliferative signaling?
-allows cells to proliferate in perpetuity
-one mutation in cell growth signaling pathways is enough to provide sustained growth signals
-occurs in the absence of the initiating cytokine
What is a proto-oncogene?
gene that encodes the normal growth-promoting proteins
What is an oncogene?
mutated version of proto-oncogene that allows cells to gain self-sufficiency from signaling
What are the characteristics of evading growth suppressors?
-“stop” signals are delivered and integrated by the products of tumor suppressor genes
-inactivation of tumor suppressor genes facilitates tumor formation
-loss of function of at least one tumor suppressor gene happens in virtually every cancer
What is apoptosis?
programmed cell death
What are the characteristics of resisting cell death?
-cells normally undergo apoptosis when damaged or when nutrients are limited
-evasion of apoptosis is an essential acquired feature in all cancers
-cells engage in autophagy to survive in nutrient-limited environment
-cells avoid death by anoikis (loss of contact inhibition) as well
What are the characteristics of enabled replicative immortality?
-normal cells undergo senescence once they reach the limit of their ability to replicate
-cells that are consistently able to keep replicating maintain their telomeres
What are the characteristics of inducing angiogenesis?
-angiogenesis is important for tumor progression and metastasis
-tumors utilize VEGF without induction to promote angiogenesis
-VEGF expression in normal cells is upregulated by hypoxia and inflammation
What are the characteristics of activating invasion and metastasis?
-cancer cells leave the primary tumor site, travel through the blood or lymph, and invade the stroma to re-establish
-ability of cancer cells to survive in hostile environment of metastatic site is crucial
What are the characteristics of genomic instability and mutation?
-“enabling” hallmark
-tumor genomes often have aneuploidy/abnormal DNA copy number
-promotes genomic instability and increased mutation count
What are the characteristics of tumor-promoting inflammation?
-“enabling” hallmark
-inflammation contributes to tumor growth and survival by supplying factors that sustain proliferation, limit cell death, and are pro-angiogenic
What is the warburg effect?
-cancer cells preferentially use glycolytic/anaerobic pathways rather than oxidative/aerobic pathways to generate energy, even in the presence of normal oxygen levels
What allows for cancer cells to be efficient glucose scavengers?
upregulation of glucose transporter GLUT-1
What are the characteristics of avoiding immune destruction?
-immunosurveillance typically prevents tumor formation
-tumor microenvironment enacts and maintains an immunosuppressive barrier
-tumors engage natural immune checkpoints to prevent their destruction
-checkpoint inhibitors are used as treatments to reactivate cytotoxic T cells
