miR-122-5p as a novel biomarker for alpha-fetoprotein-producing gastric cancer

AIM

To investigate the clinical utility of alpha-fetoprotein (AFP)-producing gastric cancer (AFPGC)-specific microRNA (miRNA) for monitoring and prognostic prediction of patients.

METHODS

We performed a comprehensive miRNA array-based approach to compare miRNA expression levels between AFP-positive and AFP-negative cells in three patients with primary AFPGC. We next examined the expression levels of the selected miRNAs in five AFPGC and ten non-AFPGC tissue samples by quantitative reverse transcription-polymerase chain reaction to validate their utility. We also investigated the expression levels of the selected miRNA not only in tissue but also in plasma samples. Moreover, we investigated the relationship between plasma AFP levels and plasma selected miRNA expression levels, and also investigated the correlation of the selected miRNA expression levels and malignant potential.

RESULTS

Among the five miRNAs selected from the miRNA array results, the expression levels of miR-122-5p were significantly higher in the AFPGC patients than in the non-AFPGC patients (P < 0.05). In tissue samples, miR-122-5p expression level tended to be lower in the non-AFPGC tissue than the normal gastric mucosa. Conversely, in the AFPGC tissue, miR-122-5p expression level was significantly higher in the AFPGC tissue than both the normal gastric mucosa and the non-AFPGC tissue samples (P < 0.05). Plasma miR-122-5p expression levels were also significantly higher in the AFPGC patients than the health volunteers and the non-AFPGC patients (P < 0.05) and were strongly correlated with plasma AFP levels (r = 0.7975, P < 0.0001). Moreover, the correlation of miR-122-5p expression in tissue samples with malignant potential was stronger than that of plasma AFP level in the AFPGC patients. In contrast, no correlation was found between miR-122-5p expression levels and liver metastasis in the non-AFPGC patients.

CONCLUSION

miR-122-5p might be a useful biomarker for early detection and disease monitoring in AFPGC.

An isolate alpha-fetoprotein producing gastric cancer liver metastasis emerged in a patient previously affected by radiation induced liver disease

We report a case of an isolated hepatic neoplasia which originated in a site of the liver previously affected by radiation induced liver disease (RILD) in a patient resected for gastric cancer and referred to us for high serum alpha-fetoprotein (AFP) levels. This case challenged us in distiguishing, even histologically, between primary liver cancer and AFP producing gastric cancer metastasis. Only a panel of immunohistochemical markers allowed the definitive diagnosis of liver metastasis of endodermal stem cell-derived and AFP producing gastric cancer. We discuss the criteria for a differential diagnosis, as well as the possible link between RILD and emergence of liver neoplasia.