Platelet-activating factor receptor (PAFR), a G-protein-coupled receptor, has been implicated in tumorigenesis, but its contributions to metastatic progression have not been investigated. Here, we show that PAFR is overexpressed in non-small cell lung cancer (NSCLC) as well as in breast, colorectal, and gastric carcinomas. Expression of PAFR correlates closely with clinical stages, survival time, and distant metastasis. In human NSCLC cells, activation of the PAF/PAFR signaling axis accentuated malignant character, including by stimulating epithelial-mesenchymal transition (EMT). In contrast, silencing PAFR in aggressive NSCLC cells inhibited these effects. Mechanistic investigations showed that PAFR stimulated EMT by activating STAT3 via upregulation of G-protein-dependent SRC or JAK2 kinase activity. Notably, STAT3 transcriptionally elevated PAFR expression. Thus, activation of PAFR in NSCLC cells initiated a forward feedback loop responsible for mediating the aggressive malignant character of NSCLC cells in vitro and in vivo. Reinforcing this reciprocal activation loop, PAF/PAFR signaling also upregulated IL6 expression and thereby STAT3 activation. Overall, our results elucidated an important role for PAFR dysregulation in the pathogenicity of NSCLC and unraveled a forward feedback loop between PAFR and STAT3 that acts to drive the malignant progression of NSCLC. Cancer Res; 75(19); 4198-210. Ó2015 AACR.

BackgroundDuring the process of metastasis, cells are subjected to various apoptotic stimuli. Aberrant expression of apoptotic regulators often contribute to cell metastasis. Heat shock protein 27(HSP27) is confirmed as an apoptosis regulator, but its antiapoptotic mechanism in metastatic hepatocellular carcinoma (HCC) cells remains unclear.MethodsLevels of HSP27 protein and its phosphorylation in Hep3B, MHCC97L to MHCC97H cells with different metastatic potentials were determined by western blot analysis. MHCC97H cells were transfected with specific small interference RNA (siRNA) against HSP27. The in vitro migration and invasion potentials of cells were evaluated by Transwell assay. The apoptosis ratio of MHCC97H cells was analyzed by TUNEL staining and Flow Cytometry. Alteration of signal transduction pathway after HSP27 knockdown in MHCC97H cells was evaluated through a Human Q Series Signal Transduction in Cancer Gene Array analysis. Nuclear NF-κB contentration and endogenous IKK activity were demonstrated by ELISA assay. The association of IKKα, IKKβ, IκBα with HSP27 and the association between IKKβ and IKKα in MHCC97H cells were determined by co-immunoprecipitation assay followed by western blot analysis.ResultsHSP27 protein and its phosphorylation increased in parallel with enhanced metastatic potentials of HCC cells. siRNA-mediated HSP27 knockdown in MHCC97H significantly suppressed cells migration and invasion in vitro and induced cell apoptosis; the prominently altered signal transduction pathway was NF-κB pathway after HSP27 knockdown in MHCC97H cells. Furthermore, inhibition of HSP27 expression led to a significant decrease of nuclear NF-κB contentration and endogenous IKK activity. In addition, HSP27 was associated with IKKα, IKKβ, IκBα in three HCC cells above. ELISA assay and western blot analysis also showed a decrease of the association between IKKβ and IKKα, the association between phosphor-HSP27 and IKK complex, and an increase of total IκBα but reducing tendency of phosphor-IκBα when HSP27 expression was efficiently knocked down in MHCC97H cells.ConclusionAltogether, these findings revealed a possible effect of HSP27 on apoptosis in metastatic HCC cells, in which HSP27 may regulate NF-kB pathway activation.

Esophageal squamous cell carcinoma (ESCC) is one of the most common malignancies worldwide and occurs at a relatively high frequency in China, yet the mechanisms underlying its devastating outcome remain unclear. Here we report that platelet-activating factor receptor (PAFR), a type of G-protein-coupled receptor, was upregulated in ESCC tumors and cell lines, compared with controls; PAFR levels were positively correlated with ESCC clinical stages and survival time. Overexpression of PAFR promoted the malignant development of ESCC in vitro and in vivo, whereas depletion of PAFR suppressed these effects. Interestingly, PAFR was observed to activate PI3K/AKT (phosphatidylinositol 3-kinase/AKT) through the upregulation of FAK kinase activity. AKT-triggered nuclear factor-κB transcriptionally activated PAFR expression. This mutual positive regulation between PAFR and AKT was required for the aggressiveness of ESCC cells both in vitro and in vivo. Furthermore, treating mice bearing ESCC tumors with cholesterol-conjugated PAFR small interfering RNA effectively inhibited tumor progression and the expression of AKT-mediated oncogenic proteins. Taken together, we made the first demonstration that dysregulation of PAFR and the positive regulatory loop between PAFR and pAKT contribute to malignant progression of ESCC.

Background Endocervical gastric-type adenocarcinoma (GAS) is a rare non-human papillomavirus-associated adenocarcinoma (NHPVA) with morphologic and immunohistochemical features of gastric differentiation. This study aimed to evaluate cytologic and clinicopathological features, differential diagnosis of endocervical GAS. Methods A total of 23 patients diagnosed with endocervical GAS/minimal deviation adenocarcinoma (MDA) at Peking University People’s Hospital between 2009 and 2018 were included. Clinical characteristics, cytologic/histopathologic findings, and immunohistochemical results were collected and analyzed. Results The average age of patients was 51 years old (range from 28 to 73). Cytologically, tall columnar epithelial cells with pale, foamy or vacuolated cytoplasm were mostly common, followed by well-defined cytoplasmic borders. Fourteen endocervical GAS cases demonstrated mild cytologic atypia, and 9 cases showed moderate to marked cytologic atypia. Ovarian and fallopian tube involvement were identified in 5 and 6 cases, respectively. Immunohistochemically, tumor cells were diffusely positive for CK7, MUC6 and CA-IX, but focally positive for CK20 and CDX2. P16 was negative or patchy positive in most cases and p53 mutation was identified in 12 cases (12/21, 57.1%). Conclusions Endocervical GAS shows different morphologic and immunological features from endocervical usual type adenocarcinoma, but it may be difficult to be differentiated from metastatic mucinous adenocarcinoma to cervix due to similar morphology and overlapping immunohistochemical profile. Therefore, awareness of the morphologic features and immunohistochemical profile of GAS will allow pathologists to recognize and accurately diagnose this rare and aggressive entity.

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BackgroundTP53 gene mutations occur in more than 50% of human cancers and the vast majority of these mutations in human cancers are missense mutations, which broadly occur in DNA binding domain (DBD) (Amino acids 102–292) and mainly reside in six “hotspot” residues. TP53 G245C and R273H point mutations are two of the most frequent mutations in tumors and have been verified in several different cancers. In the previous study of the whole genome sequencing (WGS), we found some mutations of TP53 DBD in esophageal squamous cell carcinoma (ESCC) clinical samples. We focused on two high-frequent mutations TP53 p.G245C and TP53 p.R273H and investigated their oncogenic roles in ESCC cell lines, p53-defective cell lines H1299 and HCT116 p53−/−.ResultsMTS and colony formation assays showed that mutant TP53 G245C and R273H increased cell vitality and proliferation. Flow cytometry results revealed inhibition of ultraviolet radiation (UV)- and ionizing radiation (IR)- induced apoptosis and disruption of TP53-mediated cell cycle arrest after UV, IR and Nocodazole treatment. Transwell assays indicated that mutant TP53 G245C and R273H enhanced cell migration and invasion abilities. Moreover, western blot revealed that they were able to suppress the expression of TP53 downstream genes in the process of apoptosis and cell cycle arrest induced by UV, which suggests that these two mutations can influence apoptosis and growth arrest might be due, at least in part, to down-regulate the expression of P21, GADD45α and PARP.ConclusionsThese results indicate that mutant TP53 G245C and R273H can lead to more aggressive phenotypes and enhance cancer cell malignancy, which further uncover TP53 function in carcinogenesis and might be useful in clinical diagnosis and therapy of TP53 mutant cancers.Electronic supplementary materialThe online version of this article (10.1186/s12860-018-0167-y) contains supplementary material, which is available to authorized users.

Abstract. It has been reported that the dynamic interplay between O-GlcNAcylation and O-phosphorylation is responsible for altering the activity or localization of heat-shock proteins. The aim of this study was to determine whether dynamic interplay between O-GlcNAcylation and O-phosphorylation of HSP27 in hepatocellular cancer (HCC) cells affect its entry into the nucleus. We demonstrate that the entry of HSP27 into the nucleus correlated with its phosphorylation through transfecting HCC cells with plasmids coding for wild-type HSP27 (HSP27-WT), its non-phosphorylatable (HSP27-3A) and pseudophosphorylated (HSP27-3D) mutants, however, not all of the endogenous or exogenous nuclear HSP27 was modified by phosphorylation. We observed that HSP27 was modified with O-GlcNAc glycosylation in HCC cells and report that at conserved Ser residues of HSP27, alternative phosphorylation and O-GlcNAc modification can be predicted by the YinOYang 1.2 method. Furthermore, after P79350 or combined SB203580 and PUGNAc treatment, increased nuclear import of HSP27-WT and HSP27-3D implied that the entry of HSP27 into the nucleus was not only correlated with phosphorylation, but also with O-GlcNAc glycosylation. Collectively, O-GlcNAcylation of HSP27 in HCC cells may be a novel regulatory mode of HSP27 function, particularly for its entry into the nucleus. Crosstalk or interplay between glycosylation and phosphorylation of HSP27 could regulate its subcellular localization and biological functions in liver cancer.

BRCA1 is a well established tumor suppressor gene, which is involved in many cellular processes, including DNA damage repair, cell cycle control, apoptosis, as well as transcriptional control. In this work, we have found that BRCA1 is involved in regulating TGF‐β1/Smad pathway. The loss of endogenous BRCA1 greatly attenuated TGF‐β1‐induced growth inhibition and cell cycle G1 arrest. BRCA1 greatly maintains stability of Smad4 protein, and the loss of BRCA1 results in Smad4 down‐regulation, which is likely related to its downstream gene Gadd45a. Gadd45a is able to interact with β‐Trcp1, a‐F‐box protein of SCF E3 ligase, and consequently suppresses the ubiquitin‐degradation of Smad4 by SCFβ‐trcp1, as reflected by the observations that the induction of Gadd45a substantially stabilizes Smad4 protein. In addition, exogenous expression of Gadd45a can largely rescue the protein level of Smad4 in BRCA1 deficient cells. These results further demonstrate that BRCA1 may act as an important negative regulator in cell cycle progression and tumorigenesis through regulating the stability of Smad4, and define a novel link that connects BRCA1 to TGF‐β1/Smad pathway.