Cancer Genetics Flashcards

Flashcards about Cancer Genetics

Cancer Definition

Result of uncontrolled division of abnormal cells, failure of cell cycle checkpoints and lack of regulation

Some Hallmarks of Cancer

Evading apoptosis, self-sufficiency in growth signals, insensitivity to antigrowth signals, genome instability, ability to avoid immune detection, tissue invasion and metastasis, limitless replicative potential, sustained angiogenesis

What are Driver Mutations?

Increase the probability of later mutations and epigenetic changes by conferring a growth advantage on cells or destabilizing the genome

How do cancer cells change the balance to cell proliferation?

Disrupt/Inhibit the negative regulators or increase the action of or activate the positive regulators

What are Tumor suppressor genes?

Negative regulators of cell proliferation or genes that induce apoptosis

What are Oncogenes?

Positive regulators of cell growth and proliferation or genes that are anti-apoptosis

What are gatekeeper genes?

Directly restrain cell proliferation by regulating the cell cycle

What are caretaker genes?

Indirectly restrain cell proliferation by maintaining integrity of genome

What are landscaper genes?

Indirectly restrain cell proliferation by controlling the environment around cells

What is Knudson’s Two-Hit Hypothesis?

If a person inherits a LOF allele for a Tumor Suppressor Gene, then they already have one “hit”. This increases the probability of getting a second somatic mutation or “second hit” completely inactivating the TS gene

What cells does Retinoblastoma affect?

Ganglion cells in eye during early childhood

What are Familial Cancer Syndromes?

Nearly always involve inheriting one loss-of-function allele for a Tumor Suppressor Gene, inheritance pattern is dominant, and typically lead to an earlier onset

What is Lynch syndrome?

Autosomal dominant transmission and increased risk for colon and rectal cancers (and other types)

What is an Oncogene?

Mutated proto-oncogene that allows for tumor growth/development

What is a Proto-oncogene?

The “normal” functioning gene

Categories of Function for Proto-oncogenes

Growth Factors, Growth Factor Receptors (Membrane Receptors), Proteins that phosphorylate, Transcriptional control in the nucleus

How are Proto-oncogenes activated?

Proto-oncogenes must be activated to become oncogenes through gene amplification, chromosomal rearrangement, or mutation

Oncogene Activation through Gene Amplification

Increasing copy number in a cell

Oncogene Activation by Chromosomal Rearrangement

Oncogene is relocated close to an enhancer sequence leading to abnormal activation

Genome Instability at the DNA Level

Clustered hypermutation or mutations in different types of DNA repair mechanisms

DNA Methylation profiles in Cancer Cells

General hypomethylation of DNA or hypermethylation of promoter sequences of cancer genes