L9- EMT

Definition: Metastasis is the process through which cancer spreads from its primary site to distant organs.
Statistics:
- Approximately 90% of cancer deaths are due to metastasis, while only 10% are due to primary tumors.
- Only 5% of cancer research funding is allocated to studying metastases.

Metastatic cancer retains the name of the primary cancer (e.g., breast cancer that spreads to the lungs is still referred to as metastatic breast cancer, not lung cancer).
Stage IV cancer is generally referred to metastatic cancer, indicating advanced disease.

Primary Tumor Formation: Initial tumor develops in the tissue.
Local Invasion: Cancer invades surrounding tissues.
Intravasation: Cancer cells enter the bloodstream or lymphatic system.
Circulation: Cells travel through the circulatory system to distant sites.
Extravasation: Cells exit blood vessels to form new tumors in distant organs.
Metastatic Colonization: Establishment of secondary tumors.

Epithelial-Mesenchymal Transition (EMT): A biological process where epithelial cells undergo a transformation to a mesenchymal cell phenotype, leading to increased migration and invasiveness of cancer cells.
Characteristics of EMT:
- Changes in cell adhesion properties (e.g., decreased E-Cadherin expression).
- Cytoskeletal remodeling (e.g., increased vimentin and N-cadherin).
- Acquisition of migratory and invasive capabilities.

Major changes during EMT include:
- Cytoskeletal remodeling: Reorganization of actin filaments, crucial for cell movement.
- Loss of cell polarity and adhesion: Leads to detachment of cells from the primary tumor.
- Increased motility: Enhanced ability to invade through matrices.
Reversal: The process can be reversed (MET: Mesenchymal-Epithelial Transition), allowing cells to return to an epithelial-like state.

Amoeboid vs. Mesenchymal Migration:
- Amoeboid migration: Characterized by rounded cell shapes and lower adhesiveness; common in softer matrices.
- Mesenchymal migration: Involves elongated cells and higher matrix adherence; occurs typically in stiffer environments.
- Transitions between these two modes can occur depending on the extracellular environment and internal signals.

Clinical Relevance: Understanding EMT and its reversal is crucial for cancer therapy, as targeting these transitions may offer new strategies to inhibit metastasis.
Emerging Pathways: Cancer cells can show a plastic response to treatment by switching between migration modes, posing challenges for therapeutic outcomes.

GBM is a highly aggressive brain tumor characterized by significant cellular migration and metastasis, which account for its poor prognosis (average survival is 15 months post-diagnosis).
Research focuses on inhibiting cell migration as a potential therapeutic approach to prevent tumor recurrence.

EMT is a critical process for cancer metastasis, involving changes in cell behavior and characteristics that increase the invasive potential of cancers. Understanding the stages of metastasis and the mechanisms of migration is essential for developing effective cancer therapies. Further research on EMT and its reversibility offers promising avenues for combatting cancer spread.