Abstract
Renal cell carcinoma (RCC) is the most common type of kidney cancer in adults, responsible for approximately 90‑95% of cases. We previously reported a novel method that enables direct extraction of extracellular vesicles (EVs) from surgically resected viable tissues, yielding what we term tissue‑exudative extracellular vesicles (Te‑EVs). Quantitative LC/MS analysis identified 3,871 proteins in Te‑EVs, among which leukocyte‑associated immunoglobulin‑like receptor 1 (LAIR1) was highly enriched in tumor Te‑EVs. In the present study, we found that LAIR1 was significantly upregulated in clinical specimens of human RCC tumor tissues compared to that noted in adjacent non‑cancerous renal tissues as determined by quantitative PCR analysis. LAIR1 overexpression resulted in accelerated cell proliferation and tumor growth in RCC cells. Moreover, knockdown of LAIR1 using siRNA significantly inhibited cell proliferation in RCC cells. Mechanistically, LAIR1 upregulated the phosphorylation status of Akt, which in turn increased cell proliferation in RCC cells. In clinical RCC specimens, RCC patients with high LAIR1 mRNA expression showed poor progression‑free survival compared to those with low LAIR1 expression. These findings indicate that LAIR1 promotes tumorigenesis in RCC.