The H19 long non-coding RNA is highly expressed and carries out various functions in different types of cancers. Recently, we reported that H19 contributes to the metastasis of pancreatic ductal adenocarcinoma (PDAC) cells and its inhibition reduces metastasis in vivo. However, the molecular mechanisms underlying the metastasis-promoting role of H19 in PDAC cells remain unclear. With a focus on cancer stem cells (CSCs), we elucidated the mechanisms by which H19 regulates PDAC metastasis through the overexpression and knockdown of H19 in PDAC cells. To determine whether H19 is expressed heterogeneously or homogeneously in human PDAC cells, we examined its expression in PANC-1 cells using a highly sensitive in situ hybridization technique. Under 2D-culture conditions, PANC-1 cells showed heterogeneous H19 expression and the presence of small populations of H19-expressing cells. In contrast, numerous H19-expressing PANC-1 cells were detected in 3D-cultured spheres. These results suggest that H19 is expressed in CSC-like cells among PANC-1 cells. To investigate the involvement of H19 in the development of CSC characteristics, we examined self-renewal ability, anti-cancer drug resistance, and CSC-marker expression. Sphere formation of PDAC cells depended on H19expression. However, other CSC characteristics of the cells, including CSC-marker expression and anticancer-drug resistance were unaffected by H19 levels. In addition to its role in the development of CSC characteristics, we investigated the involvement of H19 in stromal invasion, which is a key step in the metastatic cascade. Although the invasion ability of PDAC cells was dependent on H19 expression, metalloproteinase activity, a key mediator of invasion, was independent of H19 expression. During the process of invasion, a critical event is the adhesion of cancer cells to the extracellular matrix. Therefore, we investigated whether H19 contributes to this cell-to-matrix adhesion step. We found that H19 promoted cell adhesion by regulating the expression of integrins and CD24. Notably, the increased adhesion of H19-overexpressing cells was blocked by an anti-β1-integrin antibody, which resulted in the inhibition of sphere formation and invasion. Taken together, H19 plays critical roles in CSC self-renewal and cell adhesion of PDAC cells that lead to invasion and metastasis. Our findings suggest that H19 represents a novel therapeutic target for the metastasis of pancreatic cancer.
Citation Format: Norihiko Sasaki, Masashi Toyoda, Hisashi Yoshimura, Yoko Matsuda, Tomio Arai, Yoko Itakura, Fujiya Gomi, Junko Aida, Toshiyuki Ishiwata. Metastasis-promoting role of H19 long non-coding RNA in pancreatic cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3568.