Hepatocellular carcinoma (HCC) is the most common liver tumor and among the deadliest cancers worldwide. Advanced HCC overall survival is meager and has not improved over the last decade despite approval of several tyrosine kinase inhibitors (TKi) for first and second-line treatments. The recent approval of immune checkpoint inhibitors (ICI) has revolutionized HCC palliative care. Unfortunately, the majority of HCC patients fail to respond to these therapies. Here, we elaborate on the immune landscapes of the normal and cirrhotic livers and of the unique HCC tumor microenvironment. We describe the molecular and immunological classifications of HCC, discuss the role of specific immune cell subsets in this cancer, with a focus on myeloid cells and pathways in anti-tumor immunity, tumor promotion and immune evasion. We also describe the challenges and opportunities of immunotherapies in HCC and discuss new avenues based on harnessing the anti-tumor activity of myeloid, NK and γδ T cells, vaccines, chimeric antigen receptors (CAR)-T or -NK cells, oncolytic viruses, and combination therapies.

Purpose: Gastric carcinomas are heterogeneous, and the current therapy remains essentially based on surgery with conventional chemotherapy and radiotherapy. This study aimed to characterize biomarkers allowing the detection of cancer stem cells (CSC) in human gastric carcinoma of different histologic types. Experimental Design: The primary tumors from 37 patients with intestinal- or diffuse-type noncardia gastric carcinoma were studied, and patient-derived tumor xenograft (PDX) models in immunodeficient mice were developed. The expressions of 10 putative cell surface markers of CSCs, as well as aldehyde dehydrogenase (ALDH) activity, were studied, and the tumorigenic properties of cells were evaluated by in vitro tumorsphere assays and in vivo xenografts by limiting dilution assays. Results: We found that a subpopulation of gastric carcinoma cells expressing EPCAM, CD133, CD166, CD44, and a high ALDH activity presented the properties to generate new heterogeneous tumorspheres in vitro and tumors in vivo. CD44 and CD166 were coexpressed, representing 6.1% to 37.5% of the cells; ALDH activity was detected in 1.6% to 15.4% of the cells; and the ALDH+ cells represented a core within the CD44+/CD166+ subpopulation that contained the highest frequency of tumorigenic CSCs in vivo. The ALDH+ cells possessed drug efflux properties and were more resistant to standard chemotherapy than the ALDH− cells, a process that was partially reversed by verapamil treatment. Conclusions: CD44 and ALDH are the most specific biomarkers to detect and isolate tumorigenic and chemoresistant gastric CSCs in noncardia gastric carcinomas independently of the histologic classification of the tumor. Clin Cancer Res; 23(6); 1586–97. ©2016 AACR.

Gastric carcinoma is related mostly to CagA+-Helicobacter pylori infection, which disrupts the gastric mucosa turnover and elicits an epithelial-mesenchymal transition (EMT) and preneoplastic transdifferentiation. The tumor suppressor Hippo pathway controls stem cell homeostasis; its core, constituted by the large tumor suppressor 2 (LATS2) kinase and its substrate Yes-associated protein 1 (YAP1), was investigated in this context. Hippo, EMT, and intestinal metaplasia marker expression were investigated by transcriptomic and immunostaining analyses in human gastric AGS and MKN74 and nongastric immortalized RPE1 and HMLE epithelial cell lines challenged by H pylori, and on gastric tissues of infected patients and mice. LATS2 and YAP1 were silenced using small interfering RNAs. A transcriptional enhanced associated domain (TEAD) reporter assay was used. Cell proliferation and invasion were evaluated. LATS2 and YAP1 appear co-overexpressed in the infected mucosa, especially in gastritis and intestinal metaplasia. H pylori via CagA stimulates LATS2 and YAP1 in a coordinated biphasic pattern, characterized by an early transient YAP1 nuclear accumulation and stimulated YAP1/TEAD transcription, followed by nuclear LATS2 up-regulation leading to YAP1 phosphorylation and targeting for degradation. LATS2 and YAP1 reciprocally positively regulate each other's expression. Loss-of-function experiments showed that LATS2 restricts H pylori-induced EMT marker expression, invasion, and intestinal metaplasia, supporting a role of LATS2 in maintaining the epithelial phenotype of gastric cells and constraining H pylori-induced preneoplastic changes. H pylori infection engages a number of signaling cascades that alienate mucosa homeostasis, including the Hippo LATS2/YAP1/TEAD pathway. In the host-pathogen conflict, which generates an inflammatory environment and perturbations of the epithelial turnover and differentiation, Hippo signaling appears as a protective pathway, limiting the loss of gastric epithelial cell identity that precedes gastric carcinoma development.

MicroRNAs are key factors in the regulation of gene expression and their deregulation has been directly linked to various pathologies such as cancer. The use of small molecules to tackle the overexpression of oncogenic miRNAs has proved its efficacy and holds the promise for therapeutic applications. Here we describe the screening of a 640-compound library and the identification of polyamine derivatives interfering with in vitro Dicer-mediated processing of the oncogenic miR-372 precursor (pre-miR-372). The most active inhibitor is a spermine-amidine conjugate that binds to the pre-miR-372 with a K_D of 0.15 µM, and inhibits its in vitro processing with a IC₅₀ of 1.06 µM. The inhibition of miR-372 biogenesis was confirmed in gastric cancer cells overexpressing miR-372 and a specific inhibition of proliferation through de-repression of the tumor suppressor LATS2 protein, a miR-372 target, was observed. This compound modifies the expression of a small set of miRNAs and its selective biological activity has been confirmed in patient-derived ex vivo cultures of gastric carcinoma. Polyamine derivatives are promising starting materials for future studies about the inhibition of oncogenic miRNAs and, to the best of our knowledge, this is the first report about the application of functionalized polyamines as miRNAs interfering agents.