BCH3042 – Week 1: Introduction to Cell Signal Transduction

Vocabulary flashcards summarizing the major terms, molecules, and concepts presented in BCH3042 Week 1 on cell signal transduction and its relevance to cancer.

Cell Signal Transduction

The process by which a cell converts an external signal into a specific internal response, such as changes in gene expression or metabolism.

Reception (Signal Step)

The first stage of signal transduction in which a signaling molecule (ligand) binds to its receptor.

Transduction (Signal Step)

Intracellular relay of the signal through a cascade of proteins or second messengers after ligand binding.

Response (Signal Step)

The final cellular outcome triggered by a signaling pathway, e.g., proliferation, differentiation, or metabolic change.

Ligand

A molecule that specifically binds to a receptor to initiate signal transduction; examples include cytokines and hormones.

Cell-Surface Receptor

A membrane-embedded protein that binds hydrophilic ligands outside the cell and transmits signals inward.

Intracellular (Nuclear) Receptor

A cytosolic or nuclear protein that binds small hydrophobic ligands that diffuse across the plasma membrane to regulate gene transcription.

Receptor Tyrosine Kinase (RTK)

A family of enzyme-linked cell-surface receptors that dimerize and autophosphorylate tyrosine residues upon ligand binding.

Epidermal Growth Factor Receptor (EGFR)

A prototypic RTK (also called ErbB1/HER1) that controls cell proliferation and survival; hyper-activation is linked to cancer.

EGFR Family

The four ErbB receptors (EGFR/HER1, HER2, HER3, HER4); HER2 has no ligand, HER3 lacks intrinsic kinase activity.

Dimerization

Ligand-induced pairing of two receptor molecules (e.g., RTKs) that enables kinase activation.

Autophosphorylation

Self-phosphorylation of receptor tyrosine residues following dimerization, creating docking sites for signaling proteins.

G-Protein-Coupled Receptor (GPCR)

A seven-transmembrane receptor that activates heterotrimeric G proteins to relay signals; >800 members exist.

Heterotrimeric G Protein

A membrane-associated protein complex (α, β, γ subunits) that binds GTP/GDP to transmit GPCR signals.

Angiotensin II

An octapeptide hormone that binds AT1R and AT2R to regulate vasoconstriction, proliferation, and inflammation.

AT1R (Angiotensin II Type 1 Receptor)

A GPCR whose activation promotes vasoconstriction, fibrosis, inflammation, and cancer-related proliferation.

AT2R (Angiotensin II Type 2 Receptor)

A GPCR that generally mediates anti-proliferative, anti-inflammatory, and vasodilatory effects.

Nuclear Receptor

Ligand-activated transcription factor that directly binds DNA to modulate gene expression.

Estrogen Receptor (ER)

A nuclear receptor that binds estrogen; its activation drives proliferation in many breast cancers.

Tamoxifen

A selective estrogen receptor modulator (SERM) that blocks ER activity to inhibit breast cancer cell proliferation.

Cytokine

A small protein released by cells that affects the behavior of other cells, often through cell-surface receptors.

Hormone

A signaling molecule produced by glands that travels through blood to regulate distant target tissues.

Hallmarks of Cancer

Core biological capabilities acquired during tumorigenesis, such as sustaining proliferative signaling and resisting cell death.

Sustaining Proliferative Signaling

A hallmark in which cancer cells continuously activate growth pathways (e.g., via RTK mutations).

Evading Growth Suppressors

Cancer cells disable anti-proliferative signals that normally limit cell division.

Resisting Cell Death

Cancer’s ability to avoid apoptosis and other programmed cell death mechanisms.

Enabling Replicative Immortality

Unlimited replicative potential through mechanisms like telomerase activation.

Inducing Angiogenesis

Formation of new blood vessels to supply nutrients to tumors.

Activating Invasion and Metastasis

Cancer cells’ acquisition of migratory and invasive traits to spread to distant sites.

Genome Instability and Mutation

An enabling characteristic that accelerates acquisition of oncogenic changes.

Deregulating Cellular Energetics

Metabolic reprogramming (e.g., Warburg effect) that favors rapid growth.

Avoiding Immune Destruction

Cancer cells’ capability to evade recognition and elimination by the immune system.

Tumor-Promoting Inflammation

Chronic inflammatory environment that supports tumor initiation and progression.

Grb2

An adaptor protein that binds phosphorylated RTKs (like EGFR) to recruit SOS and activate Ras.

Ras/MAPK Pathway

A signaling cascade activated by RTKs that culminates in ERK-mediated gene expression driving proliferation.

PI3K/Akt Pathway

RTK-dependent pathway leading to Akt activation, promoting cell survival and growth.

Jak/STAT Pathway

A signaling route where cytokine receptors activate Jak kinases, which phosphorylate STAT transcription factors for gene regulation.