Deciphering the role of FHL1 as tumor suppressor in gallbladder cancer

Question Gallbladder cancer (GBC) is an aggressive malignancy of the gallbladder. Although it belongs to a rare disease, its incidence is rising and comprising the most common biliary tract cancer (BTC). Its molecular prognostic markers have not yet been identified and only 10 % of patients are suitable for potentially curative surgery. Therefore, a better understanding of the molecular mechanisms of GBC oncogenesis and the identification of novel potential targets for GBC therapy are urgently needed.

Methods This project is the first effort to elucidate the proteome of GBC patients and aims at characterizing the molecular function of the potential tumor suppressor genes in GBC. Quantitative mass spectrometry from Formalin-Fixed Paraffin-Embedded (FFPE) tissue of 5 GBC samples and 5 healthy gallbladder tissue samples were performed to analyse deregulated proteins in GBC. In total 4,827 proteins were detected of which 1,766 were significantly deregulated (adjusted p-val ≤ 0.05). Among these, 676 proteins were significantly downregulated and 1,090 proteins were upregulated. One of the deregulated proteins, Four and a half LIM Domains 1 (FHL1) is significantly downregulated (log2 fold change= -2.8, p-val ≤ 0.001). GBC cell lines with stable and inducible expression of FHL1 were generated to decipher the role of FHL1 in GBC.

Results Functional analysis in vitro showed that FHL1 significantly inhibits GBC cell lines proliferation and colony formation, while increases cell adhesion ability. Furthermore, molecular signaling pathway analysis demonstrated that FHL1 is linked to NOTCH pathway. Based on qPCR, FHL1 overexpression significantly downregulates transcription of typical N1ICD target genes HES1, HES4, HES7, HEY1 and c-Myc. Correspondingly, dual-reporter luciferase assay confirmed the inhibition of active N1ICD-driven transcription by overexpressing FHL1 in GBC cell lines.

Conclusion Thus, this present study underlines the important tumor-suppressive roles of FHL1 in GBC and highlights the potential role of FHL1 in NOTCH signalling.

Publikationsverlauf

Artikel online veröffentlicht:
04. Januar 2021