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← Theoretical 2

Q56 — Lysosomal Exocytosis in Cancer Cells

Theoretical 2 Real exam question — full text reproduced under IBO's CC BY-NC-SA 4.0 license
Endomembrane System & Protein Trafficking

Isolated cancer cells carry genetic changes and acquire an aggressive metastatic phenotype. One of these genetic changes is an activation of lysosomal exocytosis. The lysosomal system is one of the important participants of cancer transition, and thus, is a frequent target for cancer therapy. Lysosomal exocytosis is regulated by Ca²⁺ ions, which promote the fusion of lysosomes with the plasma membrane (PM) and the subsequent release of their contents into the extracellular matrix (ECM).

Figure. Schematic representation of downstream effects of lysosomal exocytosis in cancer cells. Endolysosomes and multivesicular bodies (MVB) fuse into the lysosome, which fuses with the plasma membrane to release proteases (cathepsins), exosomes (growth factors, transcription factors, cytokines), and cancer lysosomotrophic drugs into the ECM — converting nearby fibroblasts and macrophages into CAF (cancer-associated fibroblasts) and TAM (tumor-associated macrophages). Figure. Downstream effects of lysosomal exocytosis in cancer cells.

Determine whether the following statements are true or false.

A. Exosomes, which contain signaling molecules, leave the cell by means of lysosomal exocytosis and promote the conversion of macrophages and fibroblasts into cancer-associated fibroblasts (CAF) and tumor-associated macrophages (TAM).
B. Weakly alkaline chemotherapeutic drugs tend to accumulate in lysosomes
C. Lysosomal exocytosis enables the release of exosomes, which distribute signaling molecules to surround cells.
D. One mechanism for cancer cells to become resistant against chemotherapeutics is the efflux of chemotherapeutic drugs, which could occur through lysosomal exocytosis
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Question reproduced from IBO 2022, Theoretical Paper 2, licensed under CC BY-NC-SA 4.0 — attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)