ITM2B Truncation Promotes Migrasome Formation to Accelerate Renal Cell Carcinoma Growth

Area of Science:

• Oncology
• Cell Biology
• Biochemistry

Background:

• Integral membrane protein 2B (ITM2B) functions are mainly studied in neurological disorders, with limited research on its role in cancer.
• ITM2B undergoes frequent N-terminal cleavage, but the physiological implications of its truncated forms in cancer remain largely unexplored.

Purpose of the Study:

• To investigate the role of ITM2B truncation in renal cell carcinoma (RCC) progression.
• To elucidate the mechanism by which ITM2B truncation influences migrasome formation and cellular crosstalk in RCC.

Main Methods:

• Analysis of ITM2B truncation in RCC cells and tissues.
• Investigation of ITM2B truncation's effect on migrasome formation and content (e.g., caspase-7).
• Assessment of macrophage uptake of migrasomes and subsequent IL-6 secretion.
• Correlation of hyperuricemia with ITM2B cleavage and RCC progression.

Main Results:

• ITM2B N-terminal truncation promotes migrasome swelling and formation in RCC cells by recruiting TSPAN4.
• Truncated ITM2B facilitates the sorting of active caspase-7 into migrasomes, promoting migracytosis.
• Macrophage uptake of caspase-7-enriched migrasomes induces IL-6 secretion, creating a feedback loop that accelerates RCC growth.
• Hyperuricemia enhances ITM2B cleavage, worsening RCC progression via the ITM2B truncation-migrasome axis.
• Increased ITM2B truncations are observed in RCC tissues and patient urine, correlating with disease presence.

Conclusions:

• ITM2B truncation plays a critical role in RCC pathogenesis by modulating migrasome formation and facilitating caspase-7 transfer to macrophages.
• The ITM2B truncation-migrasome pathway, influenced by hyperuricemia, represents a novel mechanism driving RCC progression.
• ITM2B truncation-enriched migrasomes in urine may serve as a potential diagnostic biomarker for RCC.