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Abnormal activation of mTORC1 signaling occurs at high frequency in hepatocellular carcinoma (HCC). However, the underlying causes of this aberrant activation remain elusive. In this study, we identified ventricular zone expressed pleckstrin homology domain-containing 1 (VEPH1) as a novel tumor suppressor that acts via the mTORC1 axis. We performed quantitative reverse-transcription PCR (92 pairs), western blot (30 pairs), and immunostaining (225 cases) assays in HCC tissue samples to evaluate VEPH1 expression. We explored the functional effects of VEPH1 on tumor growth and metastasis. Molecular and biochemical strategies were used to gain insight into mechanisms underlying the tumor-suppressive function of VEPH1. VEPH1 is frequently silenced in HCC tissues, primarily resulting from let-7d upregulation. Decreased VEPH1 expression is associated with poor prognosis and aggressive tumor phenotypes in patients with HCC. VEPH1 mediates its tumor-suppressing activity through regulation of cell proliferation, migration and invasion in vitro and in vivo. The VEPH1 fragments 580–625aa and 447–579 aa bind directly to TSC1 (719–1,164aa) and TSC2 (1–420 aa), respectively, enhancing TSC1/TCS2 binding and promoting translocation of TSC2 to the membrane, which leads to increased TSC2 Ser1387 phosphorylation. Subsequently, Rheb is inactivated by the GTPase activity of TSC2, inhibiting mTORC1 signaling and contributing to changes in HCC carcinogenesis and metastasis. Rapamycin, the mTOR inhibitor, can inhibit the pro-tumorigenic effect of VEPH1 knockdown. Loss of VEPH1 correlates with decreased TSC2 Ser1387 phosphorylation and increased mTOR activity in HCC specimens. The loss of VEPH1 leads to aberrantly activated mTORC1 signaling in HCC; rapamycin (or rapalogs) may serve as an effective treatment option for patients with HCC and dampened VEPH1 expression. Abnormally activated mammalian target of rapamycin (mTOR) signaling is associated with poor tumor differentiation, early tumor recurrence and worse overall survival in patients with hepatocellular carcinoma. Herein, we identify low VEPH1 expression as a potential cause of abnormally activated mTOR signaling in hepatocellular carcinoma tissues. mTOR inhibitors could thus be an effective treatment option for patients with HCC and low VEPH1 expression. • Loss of VEPH1 correlates with poor prognosis in HCC. • VEPH1 acts as a tumor suppressor in HCC. • VEPH1 antagonizes mTORC1 signaling by enhancing TSC1/TSC2 binding ability. • Rapamycin inhibits VEPH1 deficiency-induced mTORC1 activation and hepatocellular carcinogenesis. [ABSTRACT FROM AUTHOR]

Protein tyrosine phosphatases (PTPs) are involved in malignant transformation and metastasis. According to one of our previous studies, Slingshot homolog 1 (SSH1), a member of PTPs, is significantly associated with the survival of intrahepatic cholangiocarcinoma (iCCA) patients. However, the underlying mechanisms of SSH1 in iCCA remain largely elusive. Here, the expression and clinical significance of SSH1 were assessed using the iCCA patient samples. The results showed that SSH1 was dramatically up-regulated in iCCA tissues and elevated SSH1 expression was associated with worse overall survival of iCCA patients. Overexpression of SSH1 accelerated the proliferation, migration, and invasion of iCCA cells, and also inhibited cell apoptosis. Furthermore, the downstream signaling pathway of SSH1 in iCCA was explored and it was revealed that the increased expression of SSH1 could activate the p38 mitogen-activated protein kinase (MAPK) pathway and enhance the expression of C-X-C motif chemokine ligand 8 (CXCL8). Notably, the high correlation of SSH1 with CXCL8 jointly indicated the poor prognosis in iCCA patients. Thus, our study suggests SSH1 as a potentially promising target for iCCA, which promoted iCCA progression through a potential p38 MAPK-CXCL8 axis. [ABSTRACT FROM AUTHOR]

Aberrant activation of Notch signaling frequently occurs in liver cancer, and is associated with liver malignancies. However, the mechanisms regulating pathologic Notch activation in hepatocellular carcinoma (HCC) remain unclear. Protein O-fucosyltransferase 1 (Pofut1) catalyzes the addition of O-linked fucose to the epidermal growth factor-like repeats of Notch. In the present study, we detected the expression of Pofut1 in 8 HCC cell lines and 253 human HCC tissues. We reported that Pofut1 was overexpressed in HCC cell lines and clinical HCC tissues, and Pofut1 overexpression clinically correlated with the unfavorable survival and high disease recurrence in HCC. The in vitro assay demonstrated that Pofut1 overexpression accelerated the cell proliferation and migration in HCC cells. Furthermore, Pofut1 overexpression promoted the binding of Notch ligand Dll1 to Notch receptor, and hence activated Notch signaling pathway in HCC cells, indicating that Pofut1 overexpression could be a reason for the aberrant activation of Notch signaling in HCC. Taken together, our findings indicated that an aberrant activated Pofut1-Notch pathway was involved in HCC progression, and blockage of this pathway could be a promising strategy for the therapy of HCC. [ABSTRACT FROM AUTHOR]

Objective: Immunotherapy targeting the programmed cell death protein-1 (PD-1)/programmed cell death protein ligand 1 (PD-L1) pathway has been observed to be efficient in several solid tumors. We aim to investigate the prognostic significance of PD-1/PD-L1 expression profile in intrahepatic cholangiocarcinoma (ICC). Materials and methods: We investigated the expression of PD-1, PD-L1, CD8+ T cells, and CD68+ macrophages in paired tumor and adjacent normal tissues from 322 ICC patients using tyramide signal amplification (TSA)-based multiplexed immunohistochemistry. Results: We found that high proportion of tumor-infiltrating CD8+ PD-1High within CD8+ PD-1+ T cells significantly correlated with advanced TNM stage (P = 0.035). ICC patients with high proportion of CD8+ PD-1High in CD8+ PD-1+ had worse postoperative survival than low proportion patients (P = 0.0037), which was an independently prognostic factor for OS (P = 0.025,). The density of CD68+ PD-L1+ significantly and positively correlated with the density of CD8+ PD-1High (P < 0.0001, r = 0.5927). The proportion of CD68+ PD-L1+ within CD68+ ICC was the risk factor for OS and TTR but not an independently factor for prognosis. The CD68+ PD-L1+ macrophages and CD8+ PD-1High T cells may cooperatively play a role in inhibiting anti-tumor immunity. Conclusion: CD68+ PD-L1+ macrophages and CD8+ PD-1High T cells predict unfavorable prognosis, which could also bring new progress about immune target therapy in ICC research. [ABSTRACT FROM AUTHOR]

As a major cellular component in tumor microenvironment, the distribution, frequency, and prognostic significance of infiltrating B cell subsets in hepatocellular carcinoma (HCC) remain controversial. Using tyramide signal amplification (TSA) based fluorescent multiplexed immunohistochemistry in situ, we evaluated the distribution and frequency of B cell subsets in two independent HCC cohorts (n = 619). The results were further confirmed by flow cytometry. Correlations of B cell subsets with clinicopathologic features and patient prognosis were analyzed. Five B cell subsets were defined by multiplexed immunohistochemistry and each subset was clearly separated by t-SNE dimension reduction analysis. Notably, the densities of all B cell subsets were significantly decreased in the tumor. The frequency of plasma cells within B cells was most abundant in the tumor. In training cohort (n = 258), high densities of tumor-infiltrating CD20+ B cells, naive B cells, IgM+ memory B cells, CD27− isotype-switched memory B cells, and plasma cells were associated with superior survival. Multivariate analysis further identified CD20+ B cells, naive B cells, and CD27− isotype-switched memory B cells as independent prognosticators for survival. Unsupervised cluster analysis confirmed increased B cell subsets harbored superior survival. In addition, high density of B cells was correlated with smaller tumor size and well differentiation. The results were validated in the independent cohort of 361 HCC patients. Intratumor infiltration of B cells is significantly impaired during HCC progression. High densities of tumor-infiltrating B cells imply a better clinical outcome. Therapies designed to target B cells may be a novel strategy in HCC. [ABSTRACT FROM AUTHOR]