180P - LHPP inhibit the cell proliferation and EMT via the TGFβ/SMAD3 signaling pathway in iCCA

Background

Intrahepatic cholangiocarcinoma(iCCA) is the second most common primary hepatic malignancy after hepatocellular carcinoma (HCC), and is also a highly malignant type of tumor. It is necessary to identify novel therapeutic targets.Histidine phosphatase LHPP were reported as a tumor suppressor for Hepatocellular Carcinoma and cervical cancer. And low level LHPP enhanced cell progression and tumor formation, and was associated with poor prognosis. So, we hypothesized that LHPP might be also related to the tumorigenesis of iCCA.

Methods

We analyzed the expression and clinical significance of LHPP in TCGA cohort and patient tissues. We transfected the iCCA cell lines with LHPP over-expression lentivirus or small interfering RNA. Cell proliferation were evaluated with the CCK-8 and colony formation assays. Cell apoptosis was evaluated by Annexin V/PI staining.Transwell assays were performed to assess cell invasion. Gene Set Enrichment Analysis (GSEA) was performed to enrich genes associated with LHPP. Markers of EMT and TGFβ/SMAD3 signaling pathway were evaluated by real-time PCR and western blotting.

Results

In this study, we found the mRNA and protein level of LHPP were downregulated in tumor tissues, and low level LHPP predicted a poor survival. LHPP overexpression suppressed RBE and HCCC-9810 cells growth and colony formation, and moderately promote cell apoptosis and EMT. In contrast, accumulated cell growth, colony formation, cell invasion and EMT were observed in LHPP knock down cells. We divided samples from the TCGA-CHOL cohort into two sub-group (LHPP_low and LHPP_High) by medina expression of LHPP, and found that TGFβ signaling pathway was significantly activated in LHPP_low group. The expression of TGFβ1 was negatively correlated with LHPP. We found that the expression of TGFβ1, TGFβ1R and p-SMAD3 were downregulated in LHPP overexpression cells, and these proteins were upregulated in LHPP down-expression cells.

Conclusions

We demonstrated that LHPP also serve as a suppressor gene to inhibit cell proliferation, cell invasion and EMT. And low level LHPP which was observed in tumor tissues predicted a poor survival. Mechanically, low level LHPP activate TGFβ/SMAD3 signaling pathway.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

Fudan University Shanghai Cancer Center.

Funding

Has not received any funding.

Disclosure

The author has declared no conflicts of interest.