Linlin Yang

Identification of biomarkers to distinguish clear cell sarcoma from malignant melanoma.

Clear cell sarcoma is a rare and malignant soft tissue tumor that shows phenotypic and immunohistochemical overlap with cutaneous malignant melanoma; identification of biomarkers that differentiate clear cell sarcoma from malignant melanoma is therefore needed. In this study, we performed mutation analysis of BRAF and NRAS, investigated the EWSR1 gene rearrangement and evaluated the protein expression of insulin-like growth factor 2 and insulin-like growth factor 1R in 31 cases of malignant melanoma and 16 cases of clear cell sarcoma. By direct sequencing and high-resolution melting analysis, we identified BRAF and NRAS mutations in 51.6% and 12.9% of malignant melanoma cases, respectively, while none of clear cell sarcoma harbored BRAF or NRAS mutations. Fluorescence in situ hybridization showed that 78.6% of clear cell sarcoma exhibited the t(12;22)(q13;q12) translocation. The presence of type 1, 2, and 3 EWSR1/ATF1 fusion gene transcripts was confirmed by reverse transcriptase polymerase chain reaction analysis, but type 4 and EWSR1/CREB1 fusion gene transcripts were not found. No fusion transcript could be detected in any of the malignant melanoma cases. Additionally, immunohistochemistry showed that the majority of clear cell sarcoma and malignant melanoma had insulin-like growth factor 2 and insulin-like growth factor receptor 1 expression; however the expression of insulin-like growth factor 1R was significantly higher in clear cell sarcoma compared to melanoma (p = .006). Our results suggest that the combination of BRAF and NRAS mutation analysis with fusion gene detection contributes to diagnosis of malignant melanoma and clear cell sarcoma, and that insulin-like growth factor 1R might be a novel target for the treatment of these two malignancies.

The diagnostic value of cytokeratin 5/6, 14, 17, and 18 expression in human non-small cell lung cancer.

Objectives: The expression patterns of cytokeratin (CK) filaments in human epithelial neoplasms are complex and distinctive. The aims of this study were to analyze CK expression and to evaluate the diagnostic application of CKs in human non-small cell lung cancer (NSCLC). Methods: mRNA expression of CK5, CK6, CK14, CK15, CK17, and CK19 was analyzed by Northern blotting. Protein expression of CK5/6, CK7, CK14, CK17, and CK18 was evaluated by immunohistochemistry on tissue microarrays. Results: Northern blotting showed that CKs were highly expressed in human bronchial epithelial cells and/or small airway epithelial cells. In NSCLC cell lines, the expression pattern of CKs was heterogeneous. Regarding protein expression of CKs in 95 primary lung tumors, expression of CK5/6, CK14, and CK17 proteins was increased in squamous cell carcinomas compared to adenocarcinomas (ADC; p = 0.001, p = 0.030, and p = 0.001, respectively), and higher expression was significantly associated with lower grading (p = 0.006, p = 0.002, and p = 0.001, respectively), while increased expression of CK7 and CK18 was observed in ADC (p = 0.001, respectively). Conclusions: Our data suggest that CK5/6, CK7, CK14, CK17, and CK18 have diagnostic value in the subclassification of NSCLC.

Human complement factor H is a novel diagnostic marker for lung adenocarcinoma

Human complement factor H (CFH), a central complement control protein, is a member of the regulators of complement activation family. Recent studies suggested that CFH may play a key role in the resistance of complement-mediated lysis in various cancer cells. In this study, we investigated the role of CFH in human lung cancer. Expression of CFH was analyzed in lung cancer cell lines by RT-PCR, Western blotting and immunofluorescence. In primary lung tumors, the protein expression of CFH was evaluated by immunohistochemistry (IHC) on tissue microarray (TMA). Binding of CFH to lung cancer cells was detected by flow cytometry. mRNA expression of CFH was detected in 6 out of 10 non-small cell lung cancer (NSCLC) cell lines, but in none of the small cell lung cancer (SCLC) cell lines. In line with Western blotting, immunofluorescence analysis demonstrated CFH protein expression in 3 NSCLC cell lines, and the immunoreaction was mainly associated with cell cytoplasm and membrane. In primary lung tumors, 54 out of 101 samples exhibited high expression of CFH and high expression was significantly correlated with lung adenocarcinoma (p=0.009). Also, in adenocarcinoma of the lung, Kaplan-Meier survival analysis showed a tendency that CFH-positive tumors had worse prognosis in comparison to CFH-negative tumors (p=0.082). Additionally, shorter survival time of patients with adenocarcinoma (<20 months) was associated with higher staining of CFH (p=0.033). Our data showed that non-small cell lung cancer cells expressed and secreted CFH. CFH might be a novel diagnostic marker for human lung adenocarcinoma.

Diagnostic and prognostic impact of desmocollins in human lung cancer

Objective Desmosomes are intercellular junctions that confer strong cell–cell adhesion. Two main members of desmosomal cadherins, desmogleins (DSGs) and desmocollins (DSCs), are involved in carcinogenesis. However, their role in human lung cancer remained elusive. The aims of this study were to analyse the expression of DSCs and to evaluate their clinical application in lung cancer. Methods The expression of DSC1-3 mRNAs was analysed by RT-PCR. The methylation status of DSCs was analysed by demethylation tests and bisulphite sequencing. Protein expression of DSCs in primary lung cancer was evaluated by immunohistochemistry on tissue microarrays. Results DSC1-3 mRNAs were downregulated in lung cancer cells, and the expression was restored in four out of seven cell lines, respectively, after 5-aza-2′-deoxycytidine treatment. A heterogeneous methylation pattern was detected by bisulphite sequencing in exon 1 of DSC2 and DSC3. In 199 patients with primary lung cancer, we found that lower protein expression of DSC1 was significantly linked to worse tumour differentiation (p=0.017), DSC3 proteins were more expressed in squamous cell carcinoma (SCC) compared with adenocarcinoma (ADC) (p<0.001), and reduced expression of DSC1 and DSC3 was significantly correlated with poor clinical outcome (p=0.045 and p=0.007, respectively). Conclusions Our data suggest that downregulation of DSC1-3 may be explained by DNA methylation, DSC1 may be a marker for tumour differentiation, DSC3 has a potential diagnostic value in subclassification of non-small cell lung carcinoma into SCC and ADC, and furthermore, DSC1 and DSC3 may be prognostic markers for lung cancer.

HOPX is methylated and exerts tumour‐suppressive function through Ras‐induced senescence in human lung cancer

HOPX acts as a tumour suppressor in various cancers. However, the regulation of HOPX in human lung cancer as well as the mechanism underlying its tumour‐suppressive function has not yet been well elucidated. Here we investigated the epigenetic regulation and molecular mechanism by which HOPX exerts growth inhibitory effects. We found that HOPX was down‐regulated in 12 out of 13 lung cancer cell lines and in 69 out of 120 primary lung tumours at mRNA and protein levels. Patients with lung adenocarcinoma (ADC) exhibited significantly more positive staining of HOPX protein compared with lung squamous cell carcinoma (SCC) (p =0.036). Again in ADC, patients with higher HOPX expression had a significantly longer disease‐free survival (p =0.001). Methylation analysis showed that down‐regulation of HOPX was associated with DNA methylation (p =0.011). To analyse the function of HOPX in lung cancer cells, stable transfection with an expression vector of HOPX was performed. It turned out that HOPX inhibited tumour cell proliferation rate, migration, and invasion, and, more interestingly, forced expression of HOPX enhanced cellular senescence via activation of oncogenic Ras and the downstream MAPK pathway, which in turn led to decreased MDM2 and increased p21. On the contrary, knockdown of HOPX by siRNA resulted in reduced Ras activity, inactivation of the MAPK pathway, and decreased p21 levels, accompanied by reduced cellular senescence. Additionally, the HOPX‐induced senescence pathway was also active in human bronchial epithelial cells. Taken together, our data suggest that down‐regulation of HOPX was related to DNA methylation and that HOPX exerts tumour‐suppressive activity by oncogenic Ras‐induced cellular senescence in lung cancer cells. Copyright

Molecular and clinicopathological analysis of dermatofibrosarcoma protuberans

Dermatofibrosarcoma protuberans (DFSP) is a dermal and subcutaneous tumor of intermediate malignancy. The most remarkable cytogenetic feature of DFSP is the chromosomal translocation t(17;22)(q22;q13), causing a fusion of the platelet-derived growth factor beta chain (PDGFB) gene at 22q13, and the collagen type 1 alpha 1 (COL1A1) at 17q22. The aim of the study was to analyze the molecular characteristic of DFSP in conjunction with histopathological and clinical features. We performed fluorescence in situ hybridization (FISH) and multiplex reverse transcriptase-polymerase chain reaction (RT-PCR) to detect chromosomal translocations and fusion gene transcripts in 16 formalin-fixed, paraffin-embedded DFSP samples. In addition, the amplification of PDGFB was also evaluated in the 16 DFSP samples by real-time PCR. FISH analysis revealed that all the 16 samples exhibited COL1A1-PDGFB gene fusion. Eleven out of 11 informative cases (100%) showed fusion transcripts by multiplex RT-PCR analysis. Various exons of the COL1A1 gene were fused with the PDGFB gene. Among them, exon 25 was found to be more frequently involved. Real-time PCR showed that the PDGFB copy number increase in the DFSP samples was higher than in normal skin tissues (p=0.007). Values of FISH fusion signals and PDGFB DNA analysis were variable between samples, but suggested that increased values might be associated with parameters of tumor progression. Our results confirm that analysis of the COL1A1-PDGFB status by FISH and RT-PCR is a useful tool in the confirmation of a DFSP diagnosis. In addition, the analysis of PDGFB copy number status may become a useful diagnostic marker since the gene is a potential target for treatment of DFSP patients.

Abstract 19: Desmoplakin has a tumor suppressive function through inhibition of Wnt/β-catenin signalling pathway in human lung cancer

Desmosomes are intercellular junctions that confer strong cell-cell adhesion thus provide resistance against mechanical stress on epithelial tissues. A body of evidence indicates that decreased expression of desmosomal proteins is associated with poor prognosis in various cancers. As a key component of desmosomal plaque proteins, the role of desmoplakin (DSP) in lung cancer is not yet elucidated. Here, we investigated the anti-tumourigenic activity of DSP in human non-small cell lung cancer (NSCLC). We found that DSP expression was downregulated in 8 out of 11 lung cancer cell lines and in 34 out of 56 primary lung tumours, and DNA methylation was responsible for gene silencing of DSP in both cell lines and primary lung tumours. Ectopic expression of DSP in NSCLC cell line H157 significantly inhibited cell proliferation, anchorage-independent growth, migration, as well as invasion, and also increased the sensitivity of NSCLC cells to apoptosis induced by an anticancer drug, gemcitabine. Furthermore, overexpression of DSP led to enhanced expression of another desmosomal plaque protein plakoglobin (also called γ-catenin), a competitor of β-catenin, resulting in decreased nuclear β-catenin levels and reduced expression of the Wnt/β-catenin target genes Axin2 and MMP14. Knockdown of DSP by siRNA resulted in downregulation of plakoglobin and upregulation of Axin2 and MMP14. Taken together, our data suggest that DSP is inactivated in lung cancer by DNA methylation, DSP increases the sensitivity to anticancer drug-induced apoptosis, and DSP has tumour suppressive function through inhibition of Wnt/β-catenin signalling pathway in NSCLC. The epigenetic regulation of DSP and its ability to increase the sensitivity to anticancer drug-induced apoptosis imply the clinical application. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 19. doi:1538-7445.AM2012-19