SERPINA4 is a novel independent prognostic indicator and a potential therapeutic target for colorectal cancer.

Serpina family A member 4 (SERPINA4), also known as kallistatin, exerts important effects in inhibiting tumor growth and angiogenesis in many malignancies. However, the precise role of SERPINA4 in CRC has not been fully elucidated. The present study aimed to investigate the expression of SERPINA4 and its clinical significance in CRC. Quantitative real-time polymerase chain reaction (qRT-PCR) and western blot analyses showed that the mRNA and protein expression of SERPINA4 in colorectal cancer (CRC) specimens was significantly decreased than that in adjacent normal mucosa. Immunohistochemistry (IHC) was conducted to characterize the expression pattern of SERPINA4 by using a tissue microarray (TMA) containing 327 archived paraffin-embedded CRC specimens. Statistical analyses revealed that decreased SERPINA4 expression was significantly associated with invasion depth, nodal involvement, distant metastasis, American Joint Committee on Cancer (AJCC) stage, and tumor differentiation. SERPINA4 was also an independent prognostic indicator of disease-free survival and overall survival in patients with CRC. Furthermore, the impact of altered SERPINA4 expression on CRC cells was analyzed with a series of in vitro and in vivo assays. The results demonstrated that SERPINA4 significantly inhibits malignant tumor progression and serves as a novel prognostic indicator and a potential therapeutic target for CRC.