19. When adenoma is converted to metastatic adenocarcinoma, which of the following combination of proteins is almost certainly to be degraded?
    (1) Type IV collagen and laminin.
    (2) Fibronectin and β₂ integrin.
    (3) Metalloprotease and serine protease.
    (4) Elastin and selectin.

(3) Metalloprotease and serine protease

Explanation:

During the progression from adenoma to metastatic adenocarcinoma, cancer cells must degrade components of the basement membrane and extracellular matrix (ECM) to invade surrounding tissues and metastasize.

• Type IV collagen and laminin (Option 1) are key components of the basement membrane that need to be broken down for invasion.

• The enzymes primarily responsible for this degradation are metalloproteases (such as matrix metalloproteinases, MMPs) and serine proteases. These proteases degrade ECM proteins, allowing tumor cells to penetrate tissue barriers, invade blood vessels, and metastasize.

• Fibronectin and β2 integrin (Option 2) are involved in cell adhesion and signaling but are not the enzymes that degrade ECM.

• Elastin and selectin (Option 4) are ECM components and adhesion molecules, respectively, not primarily targeted for degradation to enable metastasis.

Thus, the combination of metalloprotease and serine protease is the catalytic enzyme group almost certainly involved in degradation during the adenoma to metastatic adenocarcinoma conversion.​