Expression and clinical significance of adaptor-related protein complex 1 subunit Mu2 in colorectal carcinoma

Objective To explore the relations of expression of adaptor-related protein complex 1 subunit Mu2 (AP1M2) with clinical pathological features in patients with colorectal carcinoma.

Methods The cancer tissues and adjacent tissues of 97 patients with radical surgery for malignant tumor of colon from January to December 2017 in the Lianyungang City Second People′s Hospital were collected. Clinical pathological characteristic materials of patients were collected, the immunohistochemistry was used to detect the expression level of AP1M2 protein in colorectal carcinoma tissues and adjacent tissues, and the enzyme-linked immunosorbent assay was used to detect the expression of AP1M2 in serum. The relationship between the expression of AP1M2 protein and the clinical pathological characteristics in patients with malignant tumor of colon was analyzed; the Kaplan-Meier method was used to analyze the influencing factors of postoperative 5-year survival in patients with colorectal carcinoma; the bioinformatics was used to analyze the proteins and related pathways involved in AP1M2.

Results Immunohistochemical analysis showed that the expression of AP1M2 in colon cancer tissues was higher than that in adjacent tissues; among 97 pairs of specimens, there were 73 cases with high expression of AP1M2 in colon cancer tissues and 43 cases with high expression of AP1M2 in adjacent tissues, and there was a significant difference between two kinds of tissues (P=0.004). Enzyme linked immunosorbent assay showed that the expression of serum AP1M2 in cancer tissues of patients with colorectal carcinoma was significantly higher than that in the adjacent tissues (P=0.02). The ratio of high expression of AP1M2 in patients with tumor diameter>5 cm, N staging of N₁ to N₂ (with lymph node metastasis), T staging of T₃ to T₄ and postoperative 5-year recurrence was respectively significantly higher than that in patients with tumor diameter≤5 cm, N₀ staging (without lymph node metastasis), T₁ to T₂ of T staging and no postoperative 5-year recurrence (P < 0.05). After 5 years of postoperative follow-up, 5 cases died at 5 years after surgery in 24 patients with low expression of AP1M2, while 24 cases died at 5 years after surgery in 73 patients with high expression of AP1M2, and there was a significant difference (P=0.005). Cox analysis showed that AP1M2 was a risk factor for postoperative mortality of colorectal carcinoma. Biological analysis showed that AP1M2 was associated with tumor metabolism and adhesion.

Conclusion The expression level of AP1M2 is upregulated in colon cancer tissues and serum, which is related to tumor clinical staging, condition of lymph node metastasis, and prognosis of patients with colorectal carcinoma. AP1M2 can be used as a potential prognostic indicator for colorectal carcinoma.