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Questions and Answers
What type of genes are characterized by the ability to promote cell growth in the absence of normal mitogenic signals?
What type of genes are characterized by the ability to promote cell growth in the absence of normal mitogenic signals?
Which genes normally prevent uncontrolled cell growth and when mutated, lead to uncontrolled proliferation?
Which genes normally prevent uncontrolled cell growth and when mutated, lead to uncontrolled proliferation?
What is a common characteristic of genes that regulate apoptosis in cancer cells?
What is a common characteristic of genes that regulate apoptosis in cancer cells?
What is a consequence of a disability in DNA repair genes in relation to cancer development?
What is a consequence of a disability in DNA repair genes in relation to cancer development?
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What phenomenon is referred to as the accumulation of multiple mutations leading to tumor progression?
What phenomenon is referred to as the accumulation of multiple mutations leading to tumor progression?
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Which hallmark of cancer refers to the capacity of tumors to proliferate without external stimuli?
Which hallmark of cancer refers to the capacity of tumors to proliferate without external stimuli?
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What is at the heart of carcinogenesis according to the text?
What is at the heart of carcinogenesis according to the text?
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What are proto-oncogenes?
What are proto-oncogenes?
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What are oncogenes?
What are oncogenes?
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Which type of genetic damage can lead to carcinogenesis based on the text?
Which type of genetic damage can lead to carcinogenesis based on the text?
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How do tumors differ from normal cells according to the text?
How do tumors differ from normal cells according to the text?
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Which principle states that tumors result from the clonal expansion of a single progenitor cell with genetic damage?
Which principle states that tumors result from the clonal expansion of a single progenitor cell with genetic damage?
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Study Notes
Fundamental Principles of Cancer
- Cancer is a multi-step process that involves multiple genetic events (mutations) in tumors.
- Nonlethal genetic damage (mutation) is a crucial step in carcinogenesis, which can be acquired through environmental agents or inherited in the germ line.
- The genetic hypothesis of cancer states that a tumor mass results from the clonal expansion of a single progenitor cell that has sustained genetic damage.
Targets of Genetic Damage
- Growth-promoting proto-oncogenes can be targets of genetic damage.
- Growth-inhibiting tumor suppressor genes can be targets of genetic damage.
- Apoptosis-regulating genes can be targets of genetic damage.
- DNA repair genes can be targets of genetic damage.
Proto-oncogenes and Oncogenes
- Proto-oncogenes are normal cellular counterparts of oncogenes, regulating cell proliferation and differentiation.
- Oncogenes are mutant alleles of proto-oncogenes, promoting autonomous cell growth in cancer.
- Oncogenes are dominant because a single allele mutation can lead to neoplastic transformation.
- Oncoproteins are products of oncogenes, lacking important regulatory elements.
Tumor Suppressor Genes
- Tumor suppressor genes normally prevent uncontrolled growth and mutation leads to transformation.
- Both normal alleles must be damaged for transformation to occur (recessive oncogenes).
- Examples of tumor suppressor genes include P53 and Retinoblastoma genes (RB).
Genes that Regulate Apoptosis
- Genes that regulate apoptosis can be dominant or recessive.
- These genes enhance cell survival, rather than stimulating proliferation.
- Genes that protect against apoptosis are often overexpressed in cancer cells, while those that promote apoptosis are underexpressed or functionally inactivated.
DNA Repair Genes
- DNA repair genes affect cell proliferation or survival indirectly by influencing the ability to repair nonlethal damage in other genes.
- A disability in DNA repair genes can predispose to mutations in the genome and hence to neoplastic transformation.
Tumor Progression
- Carcinogenesis is a multistep process resulting from the accumulation of multiple mutations.
- Increasing malignancy is often acquired step by step.
- Tumor progression results from multiple mutations that accumulate independently in different cells, generating subclones with different characteristics.
Hallmarks of Cancer
- Self-sufficiency in growth signals: Tumors have the capacity to proliferate without external stimuli.
- Insensitivity to growth-inhibitory signals: Tumors are resistant to growth-inhibitory signals.
- Evasion of apoptosis: Tumors may be resistant to programmed cell death.
- Altered cellular metabolism: Tumors have altered cellular metabolism.
- Limitless replicative potential: Tumor cells have unrestricted proliferative capacity.
- Sustained angiogenesis: Tumors have the ability to sustain angiogenesis.
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Description
Explore the multi-step process of cancer development and the role of genetic mutations in tumors. Learn about fundamental principles such as nonlethal genetic damage and its connection to carcinogenesis.
