PPDPF Promotes the Development of Mutant KRAS-Driven Pancreatic Ductal Adenocarcinoma by Regulating the GEF Activity of SOS1.

The guanine nucleotide exchange factor (GEF) SOS1 catalyzes the exchange of GDP for GTP on RAS. However, regulation of the GEF activity remains elusive. Here, the authors report that PPDPF functions as an important regulator of SOS1. The expression of PPDPF is significantly increased in pancreatic ductal adenocarcinoma (PDAC), associated with poor prognosis and recurrence of PDAC patients. Overexpression of PPDPF promotes PDAC cell growth in vitro and in vivo, while PPDPF knockout exerts opposite effects. Pancreatic-specific deletion of PPDPF profoundly inhibits tumor development in KRASG12D -driven genetic mouse models of PDAC. PPDPF can bind GTP and transfer GTP to SOS1. Mutations of the GTP-binding sites severely impair the tumor-promoting effect of PPDPF. Consistently, mutations of the critical amino acids mediating SOS1-PPDPF interaction significantly impair the GEF activity of SOS1. Therefore, this study demonstrates a novel model of KRAS activation via PPDPF-SOS1 axis, and provides a promising therapeutic target for PDAC.

PPDPF alleviates hepatic steatosis through inhibition of mTOR signaling.

Non-alcoholic fatty liver disease (NAFLD) has become the most prevalent chronic liver disease in the world, however, no drug treatment has been approved for this disease. Thus, it is urgent to find effective therapeutic targets for clinical intervention. In this study, we find that liver-specific knockout of PPDPF (PPDPF-LKO) leads to spontaneous fatty liver formation in a mouse model at 32 weeks of age on chow diets, which is enhanced by HFD. Mechanistic study reveals that PPDPF negatively regulates mTORC1-S6K-SREBP1 signaling. PPDPF interferes with the interaction between Raptor and CUL4B-DDB1, an E3 ligase complex, which prevents ubiquitination and activation of Raptor. Accordingly, liver-specific PPDPF overexpression effectively inhibits HFD-induced mTOR signaling activation and hepatic steatosis in mice. These results suggest that PPDPF is a regulator of mTORC1 signaling in lipid metabolism, and may be a potential therapeutic candidate for NAFLD.

Chromatin remodeling factor ARID2 suppresses hepatocellular carcinoma metastasis via DNMT1-Snail axis.

Recurrence and metastasis remain the major obstacles to successful treatment of hepatocellular carcinoma (HCC). Chromatin remodeling factor ARID2 is commonly mutated in HCC, indicating its important role in cancer development. However, its role in HCC metastasis is largely elusive. In this study, we find that ARID2 expression is significantly decreased in metastatic HCC tissues, showing negative correlation with pathological grade, organ metastasis and positive association with survival of HCC patients. ARID2 inhibits migration and invasion of HCC cells in vitro and metastasis in vivo. Moreover, ARID2 knockout promotes pulmonary metastasis in different HCC mouse models. Mechanistic study reveals that ARID2 represses epithelial-mesenchymal transition (EMT) of HCC cells by recruiting DNMT1 to Snail promoter, which increases promoter methylation and inhibits Snail transcription. In addition, we discover that ARID2 mutants with disrupted C2H2 domain lose the metastasis suppressor function, exhibiting a positive association with HCC metastasis and poor prognosis. In conclusion, our study reveals the metastasis suppressor role as well as the underlying mechanism of ARID2 in HCC and provides a potential therapeutic target for ARID2-deficient HCC.

Unravelling the phylogeny, cryptic diversity and morphological evolution of Diptilomiopus mites (Acari: Eriophyoidea).

The Eriophyoidea, notable for specific morphological characters (four-legged mites) and gall-formation in host plants (gall mites), is one of the most species-rich superfamilies of Acari. Monophyly of the superfamily Eriophyoidea is accepted by all acarologists; however, monophyly of most genera has not been evaluated in a molecular phylogenetic network. Furthermore, most eriophyoid mites, especially species in the genus Diptilomiopus, are morphologically similar, challenging their identification. Here we test the phylogeny and cryptic diversity of Diptilomiopus species using fragments of two mitochondrial (COI and 12S) and two nuclear (18S and 28S) genes. Our results revealed the monophyly of Diptilomiopus. Sequence distance, barcode gap, and species delimitation analyses of the COI gene allowed us to resolve cryptic diversity of Diptilomiopus species. Additionally, we supposed that characteristics of genu fused with femur on both legs and seta ft' absent on leg II evolved only once within Diptilomiopus, which are potential morphological synapomorphies. In contrast, characteristics of both setae ft' and ft″ divided into a short branch and a long branch were supposed evolving multiple times independently. Our findings contribute to the understanding of phylogeny and morphological evolution of Diptilomiopus species and provide a DNA-based approach for species delimitation of Diptilomiopus mites.

Two new species of eriophyid mites (Acari: Eriophyidae) from Malaysia.

Two new species of the family Eriophyidae (Acari: Eriophyoidea) from Mount Trusmadi, Malaysia, are described and illustrated. They are Neodicrothrix grandcaputus sp. nov. on Stachyurus himalaicus (Stachyuraceae) and Latitudo asiaticis sp. nov. on Psychotria asiatica (Rubiaceae). Both of the two new species are vagrant on the lower leaf surface. No damage to the host was observed. In addition to the description, a key to species of Neodicrothrix is provided.

BMP10 suppresses hepatocellular carcinoma progression via PTPRS-STAT3 axis.

Bone morphogenetic protein 10 (BMP10), one member of the BMP family, is involved in various development events. Dysregulation of BMP10 has been observed in several diseases, including hypertensive cardiac hypertrophy, Hirschsprung disease and blood vessel formation. However, its role in liver cancer remains largely unknown. In this study, we reported that BMP10 was significantly downregulated in HCC at both mRNA and protein level. Decreased BMP10 was associated with bigger tumor size, worse TNM stage, earlier recurrence and poorer survival. BMP10 negatively regulated HCC cell proliferation in vitro and in vivo. Mechanism study revealed that BMP10 suppressed tumor cell growth by inhibiting STAT3 signaling. Interestingly, we found that cytoplasmic BMP10 interacted with both receptor protein tyrosine phosphatase sigma (PTPRS) and STAT3, which facilitated dephosphorylation of STAT3 by PTPRS. Altogether, our study has revealed the clinical significance of BMP10 in HCC, and suppression of HCC cell growth by BMP10 via PTPRS-STAT3 axis, providing a potential therapeutic strategy for targeting STAT3 signaling in HCC.

CHML promotes liver cancer metastasis by facilitating Rab14 recycle.

Metastasis-associated recurrence is the major cause of poor prognosis in hepatocellular carcinoma (HCC), however, the underlying mechanisms remain largely elusive. In this study, we report that expression of choroideremia-like (CHML) is increased in HCC, associated with poor survival, early recurrence and more satellite nodules in HCC patients. CHML promotes migration, invasion and metastasis of HCC cells, in a Rab14-dependent manner. Mechanism study reveals that CHML facilitates constant recycling of Rab14 by escorting Rab14 to the membrane. Furthermore, we identify several metastasis regulators as cargoes carried by Rab14-positive vesicles, including Mucin13 and CD44, which may contribute to metastasis-promoting effects of CHML. Altogether, our data establish CHML as a potential promoter of HCC metastasis, and the CHML-Rab14 axis may be a promising therapeutic target for HCC.

Liver cancer: WISP3 suppresses hepatocellular carcinoma progression by negative regulation of ß-catenin/TCF/LEF signalling.

OBJECTIVES: Wnt1-inducible signalling pathway protein 3 (WISP3/CCN6) belongs to the CCN (CYR61/CTGF/NOV) family of proteins, dysregulation of this family contributed to the tumorigenicity of various tumours. In this study, we need to explore its role in hepatocellular carcinoma that remains largely elusive. MATERIALS AND METHODS: The expression of WISP3/CCN6 was analysed by qRT-PCR and Western blotting. Effects of WISP3 on proliferation and metastasis of HCC cells were examined, respectively, by MTT assay and Boyden Chamber. Roles of WISP3 on HCC tumour growth and metastatic ability in vivo were detected in nude mice. Related mechanism study was confirmed by immunofluorescence and Western blotting. RESULTS: The expression of WISP3 was significantly downregulated in HCC clinical samples and cell lines, and reversely correlated with the tumour size. Forced expression of WISP3 in HCC cells significantly suppressed cell growth and migration in vitro as well as tumour growth and metastatic seeding in vivo. In contrast, downregulation of WISP3 accelerated cell proliferation and migration, and promoted in vivo metastasis. Further study revealed that WISP3 inhibited the translocation of ß-catenin to the nucleus by activating glycogen synthase kinase-3ß (GSK3ß). Moreover, constitutively active ß-catenin blocked the suppressive effects of WISP3 on HCC. CONCLUSIONS: Our study showed that WISP3 suppressed the progression of HCC by negative regulation of ß-catenin/TCF/LEF signalling, providing WISP3 as a potential therapeutic candidate for HCC.

FABP4 suppresses proliferation and invasion of hepatocellular carcinoma cells and predicts a poor prognosis for hepatocellular carcinoma.

Adipocyte fatty acid-binding protein (FABP4) is abundant in macrophage and adipocyte. It is known to be involved in lipid metabolism. The role of FABP4 has been reported in various cancers, such as non-small cell lung cancer, breast cancer, ovarian cancer, and prostatic cancer. However, its role remains unclear in hepatocellular carcinoma (HCC). In our study, we investigated the expression of FABP4 at both mRNA and protein levels, and by examining 175 cases of patients with cancer of the liver tissue microarray, the significance between the expression of FABP4 and clinical characteristics had been discussed. We found that FABP4 was lowly expressed in HCC tissues compared to the corresponding tissue adjacent, and the expression of FABP4 was significantly associated with the tumor size, PVTT, recurrence-free survival and overall survival. Moreover, multivariate Cox regression analysis indicated that the expression of FABP4, Alb, AFP, HBsAg, and PVTT were independent risk factors for overall survival, and the expression of FABP4, AFP, GGT, tumor size, and encapsulation were independent risk factors for HCC recurrence. In addition, we revealed that FABP4 suppressed HCC cell proliferation and invasion in vitro. Moreover, overexpression of FABP4 led to inhibit tumor growth and decreased tumor volume in vivo. These phenotypes were associated with altered expression of Snail and p-STAT3. Our studies thus suggest that FABP4 could be a potential target for HCC chemotherapy.

EphB3 Stimulates Cell Migration and Metastasis in a Kinase-dependent Manner through Vav2-Rho GTPase Axis in Papillary Thyroid Cancer.

Eph receptors, the largest subfamily of transmembrane tyrosine kinase receptors, have been increasingly implicated in various physiologic and pathologic processes, and the roles of the Eph family members during tumorigenesis have recently attracted growing attentions. In the present study, we explored the function of EphB3, one member of Eph family, in papillary thyroid cancer (PTC). We found that the expression of EphB3 was significantly elevated in PTC. Either overexpression of EphB3 or activation of EphB3 by EfnB1-Fc/EfnB2-Fc stimulated in vitro migration of PTC cells. In contrast, siRNA-mediated knockdown of EphB3 or EphB3-Fc treatment, which only blocked EphB3-mediated forward signaling, inhibited migration and metastasis of PTC cells. A mechanism study revealed that EphB3 knockdown led to suppressed activity of Rac1 and enhanced activity of RhoA. Moreover, we found that Vav2, an important regulator of Rho family GTPases, was activated by EphB3 in a kinase-dependent manner. Altogether, our work suggested that EphB3 acted as a tumor promoter in PTC by increasing the in vitro migration as well as the in vivo metastasis of PTC cells through regulating the activities of Vav2 and Rho GTPases in a kinase-dependent manner.