Difficulty: Easy
Correct Answer: All of the above
Explanation:
Introduction / Context:
Metastasis is the multi-step process by which malignant cells escape the primary tumor, invade surrounding tissues, enter the circulation, and colonize distant organs. A key hallmark is the ability to breach the extracellular matrix and basement membranes using enzymes and altered regulatory pathways.
Given Data / Assumptions:
Concept / Approach:
Invasion requires a protease-rich microenvironment. Overexpression of metalloproteinases and downregulation of their inhibitors promote matrix dissolution. Tumor cells also undergo epithelial–mesenchymal transition with enhanced motility and adhesion changes that synergize with proteolysis.
Step-by-Step Solution:
Verification / Alternative check:
Many metastatic tumors show a high MMP/TIMP ratio, correlating with invasive behavior and poor prognosis, confirming the functional importance of these changes.
Why Other Options Are Wrong:
Common Pitfalls:
Assuming metastasis depends on a single gene or enzyme. In reality, it is a coordinated program involving proteases, adhesion changes, motility signaling, and survival pathways.
Final Answer:
All of the above
Discussion & Comments