The expression of epithelial membrane protein 1 (EMP1) can help distinguish between patients with extrahepatic cholangiocarcinoma and healthy controls, according to the results of a new study published in The International Journal of Biological Markers. Moreover, low expression levels of the protein are indicative of an unfavorable prognosis.

These findings suggest that EMP1 is a feasible and credible biomarker with high accuracy, sensitivity, and specificity for both the diagnosis and prognosis of the disease.

The incidence and mortality of extrahepatic cholangiocarcinoma are increasing worldwide, but diagnosis remains difficult and prognosis is poor.

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The authors of the study stated, “EMP1 might be a feasible biomarker in [extrahepatic cholangiocarcinoma] diagnosis and contribute to predicting prognosis.” This could help early diagnosis and treatment initiation, thereby improving prognosis.

It was already known that EMP1 functions as an oncogene in various tumors. However, its clinical role in extrahepatic cholangiocarcinoma was unclear.

Here, a team of researchers from Chongqing University Three Gorges Hospital in China identified differentially expressed genes in 183 extrahepatic cholangiocarcinoma patients and 61 healthy controls. They then detected and compared the expression levels of EMP1. Finally, they compared the relationship between EMP1 expression and clinicopathological indices to verify the clinical role of the protein.

The results showed that there were 1554 downregulated and 1065 upregulated genes in extrahepatic cholangiocarcinoma. Using Gene Ontology and Kyoto Encyclopedia and Genomes analysis, the researchers found that the extracellular matrix and extracellular structure organization, cholesterol metabolism, the interleukin-17 signaling pathway, and vitamin digestion and absorption were significantly enriched and involved in targeted differentially expressed genes.

They also found that the messenger RNA (mRNA) of EMP1 was decreased in the serum samples of patients with extrahepatic cholangiocarcinoma compared to those of healthy controls. 

EMP1 expression was negatively correlated with lymph node metastasis, the stage of tumor node metastasis, and the levels of cancer antigen 19-9 and carcinoembryonic antigen.

The researchers said a larger number of samples should be analyzed in the future to confirm these findings.


Li X, Yan L, Xue H. Serum epithelial membrane protein 1 serves as a feasible biomarker in extrahepatic cholangiocarcinoma. Int J Biol Markers. Published online September 27, 2021. doi:10.1177/17246008211035142