TGF‐β induced PAR‐1 expression promotes tumor progression and osteoclast differentiation in giant cell tumor of bone

Although protease activated receptor‐1 (PAR‐1) has been confirmed as an oncogene in many cancers, the role of PAR‐1 in giant cell tumor (GCT) of bone has been rarely reported. The mechanism of PAR‐1 in tumor‐induced osteoclastogenesis still remains unclear. In the present study, we detected that PAR‐1 was significantly upregulated in GCT of bone compared to normal tissues, while TGF‐β was also overexpressed in GCT tissues and could promote the expression of PAR‐1 in a dose and time dependent manner. Using the luciferase reporter assay, we found that two downstreams of TGF‐β, Smad3 and Smad4, could activate the promoter of PAR‐1, which might explain the mechanism of TGF‐β induced PAR‐1 expression. Meanwhile, PAR‐1 was also overexpressed in microvesicles from stromal cells of GCT (GCTSCs), and might be transported from GCTSCs to monocytes through microvesicles. In addition, knockout of PAR‐1 by TALENs in GCTSCs inhibited tumor growth, angiogenesis and osteoclastogenesis in GCT in vitro. Using the chick CAM models, we further showed that inhibition of PAR‐1 suppressed tumor growth and giant cell formation in vivo. Using microarray assay, we detected a number of genes involved in osteoclastogenesis as the possible downstreams of PAR‐1, which may partly explain the mechanism of PAR‐1 in GCT. In brief, for the first time, these results reveal an upstream regulatory role of TGF‐β in PAR‐1 expression, and PAR‐1 expression promotes tumor growth, angiogenesis and osteoclast differentiation in GCT of bone. Hence, PAR‐1 represents a novel potential therapeutic target for GCT of bone.     

Breast carcinoma cells modulate the chemoattractive activity of human bone marrow‐derived mesenchymal stromal cells by interfering with CXCL12

We investigated whether breast tumor cells can modulate the function of mesenchymal stromal cells (MSCs) with a special emphasis on their chemoattractive activity towards hematopoietic stem and progenitor cells (HSPCs). Primary MSCs as well as a MSC line (SCP‐1) were cocultured with primary breast cancer cells, MCF‐7, MDA‐MB231 breast carcinoma or MCF‐10A non‐malignant breast epithelial cells or their conditioned medium. In addition, the frequency of circulating clonogenic hematopoietic progenitors was determined in 78 patients with breast cancer and compared with healthy controls. Gene expression analysis of SCP‐1 cells cultured with MCF‐7 medium revealed CXCL12 (SDF‐1) as one of the most significantly downregulated genes. Supernatant from both MCF‐7 and MDA‐MB231 reduced the CXCL12 promoter activity in SCP‐1 cells to 77% and 47%, respectively. Moreover, the CXCL12 mRNA and protein levels were significantly reduced. As functional consequence of lower CXCL12 levels, we detected a decreased trans‐well migration of HSPCs towards MSC/tumor cell cocultures or conditioned medium. The specificity of this effect was confirmed by blocking studies with the CXCR4 antagonist AMD3100. Downregulation of SP1 and increased miR‐23a levels in MSCs after contact with tumor cell medium as well as enhanced TGFβ1 expression were identified as potential molecular regulators of CXCL12 activity in MSCs. Moreover, we observed a significantly higher frequency of circulating colony‐forming hematopoietic progenitors in patients with breast cancer compared with healthy controls. Our in vitro results propose a potential new mechanism by which disseminated tumor cells in the bone marrow may interfere with hematopoiesis by modulating CXCL12 in protected niches.     

Identification of G0S2 as a gene frequently methylated in squamous lung cancer by combination of in silico and experimental approaches

Epigenetic changes can lead to abnormal expression of genes in cancer, and several genes have been reported to have aberrant promoter DNA methylation in non‐small‐cell lung cancer (NSCLC). We identified aberrantly methylated genes in NSCLC by combination of in silico and experimental approaches. We first applied bioinformatics, and from microarray datasets, we selected genes with low expression and having functions related to cancer. Next, combined bisulfite restriction analysis was carried out in 10 pooled resected lung cancer tissues to screen for genes that were aberrantly methylated, and the methylation ratio (the fraction of methylated DNA in extracted DNA from a cancer tissue sample) was quantified using quantitative analysis of methylated alleles. We identified 8 methylated genes (ARPC1B, DNAH9, FLRT2, G0S2, IRS2, PKP1, SPOCK1 and UCHL1) previously unreported in NSCLC. Analyses of methylation profiles of 101 resected lung cancer tissue samples revealed quantitatively low methylation in whole, methylation ratios were almost less than 30% even in the methylated samples, and no significant correlation to prognosis after 2 years of follow‐up using hierarchical clustering. DNA methylation of G0S2 gene was significantly more frequent in squamous lung cancer (n = 18, mean of methylation ratios: 15%) compared with nonsquamous lung cancer (n = 83, mean of methylation ratios: 2.6%) (Mann‐Whitney U test, p < 0.001). DNA methylation of G0S2 can be an important biomarker for squamous lung cancer.     

Silencing of the UCHL1 gene in human colorectal and ovarian cancers

Aberrant DNA methylation is associated with many types of human cancers. To identify genes silenced in human colorectal cancers, we performed a microarray analysis for genes whose expression was induced by treatment of HCT116 human colon cancer cells with a demethylating agent, 5-aza-2'-deoxycitidine (5-aza-dC). Seven known genes were identified as being upregulated (> or =8-fold) and expressed at more than twice as high as the average level. Among these was the UCHL1 gene (also known as PGP9.5), which is involved in regulation of cellular ubiquitin levels. A dense CpG island in its promoter region was completely methylated in HCT116 cells, and no mRNA was detected. 5-Aza-dC treatment of HCT116 cells induced dose-dependent demethylation of the CpG island, and restored UCHL1 mRNA and protein expression. UCHL1 silencing was observed in 11 of 12 human colorectal cancer cell lines, and its methylation was detected in 8 of 17 primary colorectal cancers. Further, UCHL1 silencing was observed in 6 of 13 ovarian cancer cell lines, and its methylation was detected in 1 of 17 primary ovarian cancers. These results showed that UCHL1 is inactivated in human colorectal and ovarian cancers by its promoter methylation, and suggest that disturbance of cellular ubiquitin levels is present.     

Engineered adenoviruses combine enhanced oncolysis with improved virus production by mesenchymal stromal carrier cells

Oncolytic viruses have demonstrated in pre‐clinical and clinical studies safety and a unique pleiotropic activity profile of tumor destruction. Yet, their delivery suffers from virus inactivation by blood components and sequestration to healthy tissues. Therefore, mesenchymal stromal cells (MSCs) have been applied as carrier cells for shielded virus delivery to tumors after ex vivo infection with oncolytic viruses. However, infection and particle production by MSCs have remained unsatisfying. Here, we report engineered oncolytic adenoviruses (OAds) for improved virus production and delivery by MSCs. OAds are uniquely amenable to molecular engineering, which has facilitated improved tumor cell destruction. But for MSC‐mediated regimens, OAd engineering needs to achieve efficient infection and replication in both MSCs and tumor cells. We show that an Ad5/3 chimeric OAd capsid, containing the adenovirus serotype 3 cell‐binding domain, strongly increases the entry into human bone marrow‐derived MSCs and into established and primary pancreatic cancer cells. Further, we reveal that OAd with engineered post‐entry functions—by deletion of the anti‐apoptotic viral gene E1B19K or expression of the death ligand TRAIL—markedly increased virus titers released from MSCs, while MSC migration was not hampered. Finally, these virus modifications, or viral expression of FCU1 for local 5‐FC prodrug activation, improved tumor cell killing implementing complementary cytotoxicity profiles in a panel of pancreatic cancer cell cultures. Together, our study establishes post‐entry modification of OAd replication for improving virus delivery by carrier cells and suggests a panel of optimized OAds for future clinical development in personalized treatment of pancreatic cancer.     

Fluorescent histochemical demonstration of estrogen and progesterone binding in giant cell tumors of bone: Preliminary observations

Hormonal receptors of giant cell tumors (GCTs) have not been previously reported. Five cases of GCT of bone were analyzed for estrogen and progesterone binding. Frozen sections were studied by a histochemical method, using 17-beta-6-CMOBSA-FITC and 11-alpha-hydroxyprogester-one-HS-BSA-TMRITC. Cytoplasmic fluorescence with estradiol-BSA-FITC was seen in stromal cells of all five tumors; three also showed cytoplasmic staining with progesterone-BSA-TMRITC. No fluorescence was seen in the giant cells. Two cases were also analyzed by a dextrancoated charcoal cytosol assay. No estrogen or progesterone receptor was detected by cytosol assay. This study suggests that the estrogen and progesterone binding is present in GCT of bone, possible to low-affinity sites rather than high-affinity receptors. Further investigation of hormonal receptors of GCTs of bone is warranted.     

Heterogeneous expression and functional relevance of the ubiquitin carboxyl‐terminal hydrolase L1 in melanoma

The expression of ubiquitin carboxyl‐terminal hydrolase 1 (UCHL1) is deregulated in human cancer cells with tumor inhibiting or promoting functions. Due to less knowledge on the role of UCHL1 in melanoma progression, the expression pattern and function of UCHL1 as well as the deregulated signaling pathways were characterized. A large number of melanoma cell lines, tissue microarrays of melanoma lesions and control tissues were analyzed for UCHL1 expression using PCR, Western blot and/or immunohistochemistry. The analysis revealed that melanocyte cultures, 24 of 331 melanoma lesions, two of 18 short‐term cultures and two of 19 melanoma cell lines tested, respectively, heterogeneously expressed UCHL1. The low frequency of UCHL1 expression in melanoma cells was due to gene silencing by promoter DNA hypermethylation. Using different transfection models an enzyme activity‐dependent growth promoting function of UCHL1 via the activation of the mitogen‐activated protein kinase signaling pathway was found in melanoma cells. Under oxygen stress a dose‐dependent effect of UCHL1 was detected, which was mediated by a dynamic modification of the PI3K‐Akt signaling. Thus, the aberrant UCHL1 expression in melanoma cells is linked to dynamic changes in growth properties and signal transduction cascades suggesting that UCHL1 provides a novel marker and/or therapeutic target at least for a subset of melanoma patients.     

Genetic analysis of germ cell tumors: current progress and future prospects.

Cytogenetic analysis of germ cell tumors (GCTs) has identified i(12p) as a specific cytogenetic abnormality identified in more than 80% of GCTs, present in all histologies, in primary and metastatic lesions, in testicular and extragonadal presentations, and in ovarian and sex cord stromal tumors. Other nonrandom numeric and structural chromosomal abnormalities have also been identified. Oncogene studies suggest a potential role for n-ras mutations in GCT transformation. The role of loss of tumor suppressor genes and increased genomic dosage of growth promoter genes remain areas of great interest. Leukemias and differentiated malignancies that arise in the setting of GCT appear to be clonally derived from GCT cells, with evidence of karyotypic progression and acquisition of other tumor-specific cytogenetic markers. Identification of i(12p) in poorly differentiated midline carcinomas of uncertain histogenesis can assist in the diagnosis of GCT. The presence of three or more copies of 12p may predict resistance to chemotherapy and portend a higher likelihood of treatment failure. Future cytogenetic studies in GCT promise to provide insight into the biology and treatment of all solid tumors, because GCTs are a model of chemotherapeutic responsiveness, cellular differentiation, and tumor clonal evolution.     

Combined DNA methylation and gene expression profiling in gastrointestinal stromal tumors reveals hypomethylation of SPP1 as an independent prognostic factor

Gastrointestinal stromal tumors (GISTs) have distinct gene expression patterns according to localization, genotype and aggressiveness. DNA methylation at CpG dinucleotides is an important mechanism for regulation of gene expression. We performed targeted DNA methylation analysis of 1.505 CpG loci in 807 cancer‐related genes in a cohort of 76 GISTs, combined with genome‐wide mRNA expression analysis in 22 GISTs, to identify signatures associated with clinicopathological parameters and prognosis. Principal component analysis revealed distinct DNA methylation patterns associated with anatomical localization, genotype, mitotic counts and clinical follow‐up. Methylation of a single CpG dinucleotide in the non‐CpG island promoter of SPP1 was significantly correlated with shorter disease‐free survival. Hypomethylation of this CpG was an independent prognostic parameter in a multivariate analysis compared to anatomical localization, genotype, tumor size and mitotic counts in a cohort of 141 GISTs with clinical follow‐up. The epigenetic regulation of SPP1 was confirmed in vitro, and the functional impact of SPP1 protein on tumorigenesis‐related signaling pathways was demonstrated. In summary, SPP1 promoter methylation is a novel and independent prognostic parameter in GISTs, and might be helpful in estimating the aggressiveness of GISTs from the intermediate‐risk category.     

Mesenchymal stromal cells induce epithelial‐to‐mesenchymal transition in human colorectal cancer cells through the expression of surface‐bound TGF‐β

Mesenchymal stem/stromal cells (MSC) are multipotent precursors endowed with the ability to home to primary and metastatic tumor sites, where they can integrate into the tumor‐associated stroma. However, molecular mechanisms and outcome of their interaction with cancer cells have not been fully clarified. In this study, we investigated the effects mediated by bone marrow‐derived MSC on human colorectal cancer (CRC) cells in vitro and in vivo. We found that MSC triggered epithelial‐to‐mesenchymal transition (EMT) in tumor cells in vitro, as indicated by upregulation of EMT‐related genes, downregulation of E‐cadherin and acquisition of mesenchymal morphology. These effects required cell‐to‐cell contact and were mediated by surface‐bound TGF‐β newly expressed on MSC upon coculture with tumor cells. In vivo tumor masses formed by MSC‐conditioned CRC cells were larger and characterized by higher vessel density, decreased E‐cadherin expression and increased expression of mesenchymal markers. Furthermore, MSC‐conditioned tumor cells displayed increased invasiveness in vitro and enhanced capacity to invade peripheral tissues in vivo. Thus, by promoting EMT‐related phenomena, MSC appear to favor the acquisition of an aggressive phenotype by CRC cells.     

Human papillomavirus type 16 E7 oncoprotein mediates CCNA1 promoter methylation

Human papillomavirus (HPV) oncoproteins drive distinctive promoter methylation patterns in cancer. However, the underlying mechanism remains to be elucidated. Cyclin A1 (CCNA1) promoter methylation is strongly associated with HPV‐associated cancer. CCNA1 methylation is found in HPV‐associated cervical cancers, as well as in head and neck squamous cell cancer. Numerous pieces of evidence suggest that E7 may drive CCNA1 methylation. First, the CCNA1 promoter is methylated in HPV‐positive epithelial lesions after transformation. Second, the CCNA1 promoter is methylated at a high level when HPV is integrated into the human genome. Finally, E7 has been shown to interact with DNA methyltransferase 1 (Dnmt1). Here, we sought to determine the mechanism by which E7 increases methylation in cervical cancer by using CCNA1 as a gene model. We investigated whether E7 induces CCNA1 promoter methylation, resulting in the loss of expression. Using both E7 knockdown and overexpression approaches in SiHa and C33a cells, our data showed that CCNA1 promoter methylation decreases with a corresponding increase in expression in E7 siRNA‐transfected cells. By contrast, CCNA1 promoter methylation was augmented with a corresponding reduction in expression in E7‐overexpressing cells. To confirm whether the binding of the E7–Dnmt1 complex to the CCNA1 promoter induced methylation and loss of expression, ChIP assays were carried out in E7‐, del CR3‐E7 and vector control‐overexpressing C33a cells. The data showed that E7 induced CCNA1 methylation by forming a complex with Dnmt1 at the CCNA1 promoter, resulting in the subsequent reduction of expression in cancers. It is interesting to further explore the genome‐wide mechanism of E7 oncoprotein‐mediated DNA methylation.     

唑来膦酸诱导骨巨细胞瘤基质细胞向成骨细胞分化的实验研究

目的　探讨唑来膦酸诱导骨巨细胞瘤基质细胞向成骨细胞分化的可行性。方法　取我院收治的７例唑来膦酸治疗前后的患者肿瘤组织切片行ＨＥ染色、茜素红染色、碱性磷酸酶（ＡＬＰ）染色以及成骨前因子Ⅰ型胶原和骨唾液蛋白（ＢＳＰ）的免疫组化染色。取１０例未予唑来膦酸治疗的患者术中切除的骨巨细胞瘤新鲜组织进行原代培养,待骨巨细胞瘤基质细胞贴壁生长后分别给予１μｍｏｌ／Ｌ唑来膦酸诱导１２天后行ＡＬＰ染色、免疫组化法检测Ⅰ型胶原和ＲＴ-ＰＣＲ检测Ｃｂｆａ-１的表达。结果　（１）唑来膦酸治疗前,肿瘤组织切片中骨巨细胞瘤基质细胞ＢＳＰ染色阴性或低至中度阳性、Ⅰ型胶原染色阴性或轻度阳性,茜素红和ＡＬＰ染色均为阴性;治疗后,茜素红染色阳性,ＡＬＰ染色弱阳性,ＢＳＰ和Ⅰ型胶原染色均转为强阳性,３例患者组织切片中ＨＥ染色发现类骨质或骨矿化的增加。（２）原代培养的骨巨细胞瘤基质细胞中予１μｍｏｌ／Ｌ唑来膦酸诱导１２天,空白对照组ＡＬＰ和Ⅰ型胶原染色均为弱阳性表达,唑来膦酸诱导组呈阳性表达。ＲＴ-ＰＣＲ检测发现唑来膦酸诱导组骨巨细胞癌基质细胞中Ｃｂｆａ-１表达,而空白对照组未见Ｃｂｆａ-１表达。结论　体内外研究初步证实,骨巨细胞瘤基质细胞具有向成骨细胞分化的潜能并在唑来膦酸的诱导下向成骨细胞分化,这从细胞和分子生物学水平部分解释了临床上长期应用唑来膦酸治疗后肿瘤病灶和术后残留囊壁中的明显骨生成的现象。     

Role of ERCC1 promoter hypermethylation in drug resistance to cisplatin in human gliomas

Overexpression of ERCC1 mRNA is associated with drug resistance to cisplatin in human gliomas, but the role of the ERCC1 promoter in drug resistance has not been demonstrated. We have used sodium bisulfite sequencing to compare ERCC1 promoter methylation patterns in cisplatin‐sensitive and cisplatin‐resistant glioma cells. The levels of ERCC1 DNA methylation, mRNA and protein in 32 human glioma samples were examined by methylation specific PCR, real‐time RT‐PCR and immunohistochemistry, respectively. Meanwhile, cisplatin sensitivities to these human glioma samples were tested by histoculture drug response assay. Hypermethylation was observed in the upstream 5Kb region of the ERCC1 promoter of cisplatin‐sensitive glioma cell lines. ERCC1 DNA methylation levels were highly variable in 32 human glioma samples ranging from 0.1 to 0.87, which have shown significant difference between cisplatin‐sensitive samples and cisplatin‐resistant samples (p < 0.05). The relative expression levels of ERCC1 mRNA in 32 glioma samples were also variable from 0.01 to 5.71. No detectable or low expression of ERCC1 protein was shown in 7 glioma samples. ERCC1 promoter methylation was inversely correlated to mRNA expression (r = ?0.903 p = 0.001) as well as protein expression (r = ?0.884 p = 0.001). Moreover, ERCC1 mRNA expression was significantly associated with protein levels (r = 0.840 p = 0.001). In summary, the aberrant CpG island methylation in ERCC1 promoter region exists in human glioma cell lines as well as clinical glioma samples. ERCC1 DNA methylation could regulate the expression of downstream mRNA and protein, and was associated with cisplatin chemosensitivity.