Molecular Basis of Cancer: Genetic Alterations

Monoclonality signifies that tumors originate from a single progenitor cell line, unlike non-neoplastic tissues which are polyclonal, indicating diverse cell origins.

Carcinogenesis is a multistep process involving the accumulation of multiple genetic alterations that lead to the transformed phenotype and associated hallmarks of cancer.

Tumor heterogeneity arises from continuous mutations, resulting in genetically diverse tumor cells that can exhibit varying behaviors and resistance to treatments.

<p>Genetic abnormalities can arise from inherited mutations or induced mutations caused by carcinogenic agents such as chemicals, viruses, or radiation.</p> Signup and view all the answers

<p>Regulatory genes control cell mitosis, aging, and apoptosis; when damaged, they can disrupt these processes, resulting in uncontrolled cell growth and malignancy.</p> Signup and view all the answers

<p>The 'two-hit theory' posits that both alleles of a tumor suppressor gene must be inactivated for cancer to develop, highlighting the necessity of genetic mutations for carcinogenesis.</p> Signup and view all the answers

<p>Ongoing mutations during tumor progression lead to increasingly malignant phenotypes, enhancing traits like excessive growth and invasiveness.</p> Signup and view all the answers

<p>The hallmarks of cancer include traits like sustained growth, evasion of apoptosis, and metastasis; they are critical for recognizing the fundamental mechanisms that enable tumor survival and proliferation.</p> Signup and view all the answers

<p>Proto-oncogenes are growth-promoting genes that facilitate cell proliferation and inhibit differentiation, essential for maintaining healthy tissues.</p> Signup and view all the answers

<p>Oncogenes are mutated or overexpressed versions of proto-oncogenes that promote uncontrolled cell growth and proliferation.</p> Signup and view all the answers

<p>The Ras gene encodes a signal-transduction protein, and its mutations can lead to uncontrolled growth signals associated with various cancers.</p> Signup and view all the answers

<p>Tumor suppressor genes control cell cycle progression, repair DNA, inhibit replication, and signal for apoptosis in response to DNA damage.</p> Signup and view all the answers

<p>Oncogenes exhibit a dominant inheritance pattern, where mutation in a single allele can drive the oncogenic process.</p> Signup and view all the answers

<p>BCL2 is an anti-apoptotic gene that is overexpressed in follicular lymphoma, contributing to cancer cell survival.</p> Signup and view all the answers

<p>The P53 gene prevents genome mutations by regulating the cell cycle and inducing apoptosis in response to DNA damage.</p> Signup and view all the answers

<p>DNA repair genes regulate the repair of DNA damage and maintain the integrity of DNA during replication.</p> Signup and view all the answers

<p>Apoptosis regulatory genes control programmed cell death, and their mutations may inhibit apoptosis, allowing abnormal cells to survive and proliferate.</p> Signup and view all the answers

<p>Growth suppressor genes are considered recessive because both normal alleles typically need to be damaged to enable cancerous transformation.</p> Signup and view all the answers

<p>One hallmark is the ability of tumors to proliferate without external stimuli, often due to oncogene activation.</p> Signup and view all the answers

<p>The HER2 gene encodes protein receptors that play a significant role in the growth and division of breast cancer cells.</p> Signup and view all the answers

<p>Evasion of apoptosis allows tumor cells to resist programmed cell death, leading to increased survival and proliferation.</p> Signup and view all the answers

<p>Mutations in the RB gene are primarily associated with retinoblastoma and osteosarcoma.</p> Signup and view all the answers

<p>Point mutations in proto-oncogenes typically produce a gain-of-function, while point mutations in tumor suppressor genes reduce or disable the function of the encoded protein.</p> Signup and view all the answers

<p>Sustained angiogenesis provides tumors with a vascular supply, delivering nutrients and oxygen necessary for growth.</p> Signup and view all the answers

<p>The BCR-ABL fusion gene results from a balanced reciprocal translocation between chromosomes 9 and 22, leading to the production of a tyrosine kinase that drives malignancy.</p> Signup and view all the answers

<p>Limitless replicative potential refers to a tumor's ability to proliferate indefinitely, bypassing normal cellular senescence.</p> Signup and view all the answers

<p>Cancer cells exploit various alterations in their surface markers and signaling pathways to evade detection by the immune system.</p> Signup and view all the answers

<p>Deletions can lead to the complete loss of tumor suppressor genes like TP53, which is crucial for controlling cell growth and preventing cancer.</p> Signup and view all the answers

<p>Tumor cells undergo a metabolic switch to aerobic glycolysis, enabling them to produce necessary macromolecules for rapid growth.</p> Signup and view all the answers

<p>Gene amplification can convert proto-oncogenes into oncogenes, as seen with HER2 in breast cancer, leading to overexpression and increased cancer cell growth.</p> Signup and view all the answers

<p>One mechanism is point mutations, which involve an alteration of a single base in the DNA chain.</p> Signup and view all the answers

<p>Targeting oncogenes allows for the development of drugs that specifically attack cancer cells while minimizing damage to healthy cells.</p> Signup and view all the answers