Histologic examination of an infiltrating breast carcinoma shows discohesive tumor cells arranged in single-file cords within a fibrous stroma. Immunohistochemistry demonstrates absence of E-cadherin membrane staining. Loss of this molecule promotes invasion primarily by:

• A Increasing secretion of matrix metalloproteinases
• B Enhancing angiogenesis through VEGF upregulation
• C Blocking apoptosis through AKT pathway activation
• D Disrupting cell-to-cell adhesion mediated by calcium-dependent homotypic junctions ✓

Explanation

E-cadherin is a transmembrane glycoprotein that mediates calcium-dependent, homotypic cell-to-cell adhesion through adherens junctions. Its loss, whether by mutation, silencing, or proteolytic cleavage, allows tumor cells to detach from one another and invade individually, producing the classic single-file pattern of invasive lobular carcinoma of the breast. Metalloproteinase secretion relates to basement membrane degradation, and VEGF and AKT effects concern angiogenesis and survival respectively, none of which explains discohesion.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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