A 62-year-old woman is diagnosed with invasive ductal carcinoma of the breast. Pathologic evaluation reveals distant metastasis to the bone. To establish this distant metastasis, the neoplastic cells must have completed a series of complex biological steps known as the metastatic cascade. Arrange the following critical events of the metastatic cascade in the correct chronological sequence.
- 1Downregulation of E-cadherin leading to cellular detachment from the primary tumor mass
- 2Secretion of matrix metalloproteinases to degrade the local basement membrane
- 3Intravasation into the local vascular or lymphatic circulation
- 4Adhesion to distant vascular endothelium and subsequent extravasation
Cevap
The correct sequence begins with cell detachment via E-cadherin downregulation, followed by basement membrane degradation via matrix metalloproteinases, intravasation into the circulation, and finally adhesion and extravasation at the distant site.
Metastasis requires a precise sequence of events. First, tumor cells lose their adhesion to each other (via loss of E-cadherin). Next, they secrete proteolytic enzymes like matrix metalloproteinases to dissolve the basement membrane. Only after breaching this barrier can they move through the interstitial connective tissue and intravasate into blood or lymphatic vessels. Finally, the surviving circulating tumor cells must adhere to the endothelium at a distant site and extravasate into the surrounding tissue to form a new tumor.
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Anahtar Kavram
The metastatic cascade follows an ordered physiological sequence: cellular detachment (loss of E-cadherin), local invasion (metalloproteinases degrading the basement membrane), intravasation into the circulation, and extravasation into the target organ.
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