SCCRO (DCUN1D1) induces extracellular matrix invasion by activating matrix metalloproteinase 2

DCUN1D1 and neddylation: Potential targets for cancer therapy

Cancer affects millions of people and understanding the molecular mechanisms related to disease development and progression is essential to manage the disease. Post-translational modification (PTM) processes such as ubiquitination and neddylation have a significant role in cancer development and progression by regulating protein stability, function, and interaction with other biomolecules. Both ubiquitination and neddylation are analogous processes that involves a series of enzymatic steps leading to the covalent attachment of ubiquitin or NEDD8 to target proteins. Neddylation modifies the CRL family of E3 ligase and regulates target proteins' function and stability. The DCUN1D1 protein is a regulator of protein neddylation and ubiquitination and acts promoting the neddylation of the cullin family components of E3-CRL complexes and is known to be upregulated in several types of cancers. In this review we compare the PTM ubiquitination and neddylation. Our discussion is focused on the neddylation process and the role of DCUN1D1 protein in cancer development. Furthermore, we provide describe DCUN1D1 protein and discuss its role in pathogenesis and signalling pathway in six different types of cancer. Additionally, we explore both the neddylation and DCUN1D1 pathways as potential druggable targets for therapeutic interventions. We focus our analysis on the development of compounds that target specifically neddylation or DCUN1D1. Finally, we provide a critical analysis about the challenges and perspectives in the field of DCUN1D1 and neddylation in cancer research. KEY POINTS: Neddylation is a post-translational modification that regulates target proteins' function and stability. One regulator of the neddylation process is a protein named DCUN1D1 and it is known to have its expression deregulated in several types of cancers. Here, we provide a detailed description of DCUN1D1 structure and its consequence for the development of cancer. We discuss both the neddylation and DCUN1D1 pathways as potential druggable targets for therapeutic interventions and provide a critical analysis about the challenges and perspectives in the field of DCUN1D1 and neddylation in cancer research.

DCUN1D1 Is an Essential Regulator of Prostate Cancer Proliferation and Tumour Growth That Acts through Neddylation of Cullin 1, 3, 4A and 5 and Deregulation of Wnt/Catenin Pathway

Defective in cullin neddylation 1 domain containing 1 (DCUN1D1) is an E3 ligase for the neddylation, a post-translational process similar to and occurring in parallel to ubiquitin proteasome pathway. Although established as an oncogene in a variety of squamous cell carcinomas, the precise role of DCUN1D1 in prostate cancer (PCa) has not been previously explored thoroughly. Here, we investigated the role of DCUN1D1 in PCa and demonstrated that DCUN1D1 is upregulated in cell lines as well as human tissue samples. Inhibition of DCUN1D1 significantly reduced PCa cell proliferation and migration and remarkably inhibited xenograft formation in mice. Applying both genomics and proteomics approaches, we provide novel information about the DCUN1D1 mechanism of action. We identified CUL3, CUL4B, RBX1, CAND1 and RPS19 proteins as DCUN1D1 binding partners. Our analysis also revealed the dysregulation of genes associated with cellular growth and proliferation, developmental, cell death and cancer pathways and the WNT/β-catenin pathway as potential mechanisms. Inhibition of DCUN1D1 leads to the inactivation of β-catenin through its phosphorylation and degradation which inhibits the downstream action of β-catenin, reducing its interaction with Lef1 in the Lef1/TCF complex that regulates Wnt target gene expression. Together our data point to an essential role of the DCUN1D1 protein in PCa which can be explored for potential targeted therapy.

The Development of Methods for the Production of New Molecular Vaccines and Appropriate RNA Fragments to Counteract Unwanted Genes: A Pilot Study

The potential of viruses as appropriate vectors for the development of new therapeutic strategies, as well as for the design of molecular (DNA, RNA, and/or protein) vaccines via substitution of nucleotide sequences, has been proven. Among the most appropriate DNA and/or RNA fragments, members belonging to families Parvoviridae (particularly adeno-associated virus, AAV) and Poxviridae have frequently been suggested for this purpose. In previous studies, the vaccine avipoxvirus strains FK (fowl) and Dessau (pigeon) have been proven able to infect mammalian cells (as well as avian cells), and to replicate productively in a small number of them; thus, we may be able to adapt them using incubation, and in these conditions. Additionally, we have previously proved, based on AAV recombinant DNA vectors, that it is possible to transfer appropriate genes of interest via mouse embryonic stem cells (mESCs). In the current study, we develop methods for the application of the same vaccine avipoxviral strains, based on the AAV DNA genome recombinant constructs, to be used for gene transfer in cells, for the transfer of DNA and/or RNA fragments (for the suppression of unwanted viral and/or cellular genes), and for the production of molecular (DNA, RNA, and/or protein) anti-cancer and anti-viral vaccines. To this end, sub-populations of embryonic mammalian cells infected with the two forms of both vaccine avipoxviral strains were frozen in the presence of cryo-protector dimethylsulfoxide (DMSO), subsequently thawed, and re-incubated. In most cases, the titers of the intra-cellular forms of the two strains were higher than those of their extra-cellular forms. These data were explained by the probable existence of the intra-cellular forms as different sub-forms, including those integrated in the cellular genome proviruses at a given stage of the cellular infection, and suggest the possibility of transferring nucleotide (DNA and/or RNA) fragments between cellular and viral genomes; this is due to the influence of activated fusion processes on DMSO, as well as drastic temperature variations.

DCUN1D1, a new molecule involved in depigmentation via upregulating CXCL10

CD8⁺ T cells in the lesioned site play a crucial role in the pathogenesis of vitiligo. The chemokine CXCL10 secreted by keratinocytes regulates the migration of CD8⁺ T cells into the skin. In our previous study, we found that DCUN1D1 expression in vitiligo lesions positively correlates with Cxcl10 expression. In this study, the regulatory effect of DCUN1D1 on CXCL10 and cell function was investigated. DCUN1D1 protein expression was significantly higher in the skin tissue from vitiligo lesions compared with samples from healthy controls. High expression of DCUN1D1 in keratinocytes caused local hair depigmentation in mice, reduced melanin content, high infiltration of CD8⁺ T cells and increased CXCL10 expression. This suggested that DCUN1D1 may regulate CD8⁺ T-cell infiltration and depigmentation through CXCL10. Inhibition of DCUN1D1 expression in HaCaT cells abolished the IFN-γ-induced upregulation of p-JAK1, p-STAT1 and CXCL10, suppressed the H₂ O₂ -induced ROS generation and apoptosis, and upregulated tyrosinase expression in melanocytes. Collectively, these results show that DCUN1D1 is an important regulator of CXCL10 and may be a new target for the treatment of vitiligo.

Evaluation of HZX-960, a novel DCN1-UBC12 interaction inhibitor, as a potential antifibrotic compound for liver fibrosis

Liver fibrosis is a very common health problem and currently lacks effective treatments. Cullin ring E3 ligases (CRLs) regulate the turnover of ~20% of mammalian cell proteins. Neddylation, the process by which NEDD8 is covalently attached to cullin proteins through sequential enzymatic reactions, is critical for the activation of CRLs and was recently found to be elevated in liver fibrosis. NEDD8-activating enzyme E1-specific inhibition led to the reduced liver damage characterized by decreased apoptosis, inflammation and fibrosis. However, the relevance of a co-E3 ligase, DCN1, in liver fibrosis remains unclear. Here, a novel and potent DCN1-UBC12 interaction inhibitor HZX-960 was discovered with an IC50 value of 9.37nM, which could inhibit the neddylation of cullin3. Importantly, we identified that HZX-960 treatment could attenuate TGFβ-induced liver fibrotic responses by reducing the deposition of collagen I and α-SMA, and upregulating cellular NRF2, HO-1 and NQO1 level in two hepatic stellate cell lines. Additionally, DCN1 was shown to be unregulated in CCl4-induced mice liver tissue, and liver fibrotic signaling in mice was reduced by HZX-960. Therefore, our data demonstrated that HZX-960 possessed anti-liver fibrosis ability, and DCN1 may be a potential therapeutic target for liver fibrosis treatment.

MicroRNA-3148 inhibits glioma by decreasing DCUN1D1 and inhibiting the NF-kB pathway

Glioma, which originates in the brain, is the most aggressive tumor of the central nervous system. It has been shown that microRNA (miRNA) controls the proliferation, migration and apoptosis of glioma cells. The objective of the present study was to measure microRNA-3148 (miR-3148) expression and investigate its impact on the pathogenetic mechanism of glioma. In the present study, reverse transcription-quantitative real-time PCR was employed to detect miR-3148 expression levels in glioma tissues and cell lines. Cell Counting Kit-8 assay, 5-ethynyl-2'-deoxyuridine assay, and Transwell migration assay were performed to assess the influence of miR-3148 on the malignant biological behavior of glioma cells. The biological functions of miR-3148 in glioma were examined via a xenograft tumor growth assay. Furthermore, the association between miR-3148 and DCUN1D1 was investigated via immunohistochemistry, dual-luciferase reporter assay and western blotting. It was observed that miR-3148 was expressed at low levels in glioma cells, and this represented a poor survival rate. In addition, an increased level of miR-3148 in cells and animal models inhibited glioma cell migration and proliferation. Moreover, miR-3148 decreased DCUN1D1 and curbed the nuclear factor κ enhancer binding protein (NF-κB) signaling pathway, thus decreasing the growth of glioma. Thus, miR-3148 is expressed within glioma tissues at low levels where it suppresses glioma by curbing the NF-κB pathway and lowering DCUN1D1.

Evidence for frequent concurrent DCUN1D1, FGFR1, BCL9 gene copy number amplification in squamous cell lung cancer

Non-small cell lung cancer (NSCLC) targeted therapies are mostly based on activating mutations and rearrangements which are rare events in Lung Squamous Cell Carcinomas (LUSC). Recently advances in immunotherapy have improved the therapeutic repository for LUSC, but there is still an urgent need for novel targets and biomarkers. We examined 73 cases of LUSC for relative copy number amplification of DCUN1D1, BCL9, FGFR1 and ERBB2 genes and searched for correlations with molecular alterations and clinicopathological characteristics. In our cohort BCL9 gene was amplified in 57.5 % of the cases, followed by DCUN1D1 in 37 %, FGFR1 in 19 % whereas none of the cases were amplified in ERBB2 gene. The majority of the samples exhibited amplification in at least one gene while half of them displayed concurrent amplification of two/three genes. Interestingly, 93 % of the FGFR1 amplified cases were also found co amplified with DCUN1D1 and/or BCL9 genes. Linear correlations were found between BCL9 and DCUN1D1 as well as BCL9 and FGFR1 gene amplification. BCL9 and DCUN1D1 genes' amplification was correlated with poorly differentiated tumors (p = 0.035 and p = 0.056 respectively), implying their possible role in tumor aggressiveness. This is the first study, to the best of our knowledge that examines the correlation of DCUN1D1 and BCL9 genes relative copy number amplification with molecular alterations and clinicopathologic characteristics of squamous cell lung cancer tissue samples. Our findings show concurrent amplification of genes in different chromosomes, with possible involvement in tumor aggressiveness. These results support the complexity of LUSC tumorigenesis and imply the necessity of multiple biomarkers / targets for a more effective therapeutic result in LUSC.

Development of phenyltriazole thiol-based derivatives as highly potent inhibitors of DCN1-UBC12 interaction

Defective in cullin neddylation 1(DCN1) is a co-E3 ligase that is important for cullin neddylation. Dysregulation of DCN1 highly correlates with the development of various cancers. Herein, from the initial high-throughput screening, a novel hit compound 5a containing a phenyltriazole thiol core (IC₅₀ value of 0.95 μM for DCN1-UBC12 interaction) was discovered. Further structure-based optimization leads to the development of SK-464 (IC₅₀ value of 26 nM). We found that SK-464 not only directly bound to DCN1 in vitro, but also engaged cellular DCN1, suppressed the neddylation of cullin3, and hindered the migration and invasion of two DCN1-overexpressed squamous carcinoma cell lines (KYSE70 and H2170). These findings indicate that SK-464 may be a novel lead compound targeting DCN1-UBC12 interaction.

Discovery of Novel Pyrazolo-pyridone DCN1 Inhibitors Controlling Cullin Neddylation

Chemical control of cullin neddylation is attracting increased attention based largely on the successes of the NEDD8-activating enzyme (E1) inhibitor pevonedistat. Recently reported chemical probes enable selective and time-dependent inhibition of downstream members of the neddylation trienzymatic cascade including the co-E3, DCN1. In this work, we report the optimization of a novel class of small molecule inhibitors of the DCN1-UBE2M interaction. Rational X-ray co-structure enabled optimization afforded a 25-fold improvement in potency relative to the initial screening hit. The potency gains are largely attributed to additional hydrophobic interactions mimicking the N-terminal acetyl group that drives binding of UBE2M to DCN1. The compounds inhibit the protein-protein interaction, block NEDD8 transfer in biochemical assays, engage DCN1 in cells, and selectively reduce the steady-state neddylation of Cul1 and Cul3 in two squamous carcinoma cell lines harboring DCN1 amplification.

Potent 5-Cyano-6-phenyl-pyrimidin-Based Derivatives Targeting DCN1-UBE2M Interaction

Neddylation of the Cullin-RING E3 ligases (CRLs) regulates the homeostasis of approximately 20% of cellular proteins. Defective in cullin neddylation 1 (DCN1), as a co-E3 ligase, interacts with UBE2M to enhance the activation of CRLs, and this interaction is emerging as a therapeutic target for human diseases. Here, we present a series of pyrimidin-based small molecular inhibitors targeting DCN1-UBE2M interaction. After finding a novel inhibitor DC-1 with IC₅₀ = 1.2 μM, we performed a series of chemical optimizations, which finally led to the discovery of a potent thiazole containing 5-cyano-6-phenylpyrimidin-based inhibitor DC-2 (IC₅₀ = 15 nM). Next, using protein and cellular thermal shift assays, coimmunoprecipitation, molecular docking, and site-specific mutation experiments, we further proved that DC-2 specifically inhibited the interaction of UBE2M and DCN1 at molecule and cellular levels, resulting in the decrease of cullin3 neddylation and accumulation of its substrate, NRF2. Our findings indicate that DC-2 may serve as a novel lead compound for specific derivatives targeting DCN1-UBE2M interaction.

DCUN1D1 facilitates tumor metastasis by activating FAK signaling and up-regulates PD-L1 in non-small-cell lung cancer

E3 ubiquitin ligases, which are key enzymes in the ubiquitin proteasome system, catalyze the ubiquitination of proteins to target them for proteasomal degradation. Emerging evidence suggests that E3 ubiquitin ligases play important roles in the development and progression of lung cancer. In our study, we characterized the gene expression landscape of lung cancer using data obtained from TCGA to explore the changes in E3 ubiquitin ligase containing the regulators of E3 ubiquitin ligase activity. Overall, most gene expression changes occurred in NSCLC tissues compared with adjacent normal ones. In total, 48 E3 ubiquitin ligases containing the regulators were up-regulated in NSCLC tissues compared with their levels in normal tissues. We analyzed the expression of up-regulated E3 ubiquitin ligases containing the regulators in two publicly available transcriptome data sets (GSE13213 and GSE30219). We found that four E3 ubiquitin ligases (UHRF1, BRCA1, TRAIP and HLTF) and one regulator of ubiquitin E3 activity DCUN1D1 that were dramatically up-regulated in cancer were significantly associated with tumor metastasis and patient's poor prognosis both in two transcriptome data sets. Next, clinical analysis indicated that the expression levels of DCUN1D1 correlated with clinical stage and lymph node metastasis in NSCLC patients as determined by quantitative reverse transcription-PCR. Furthermore, functional assays showed that DCUN1D1 promoted NSCLC cell invasion and migration as determined by transwell assay in vitro. Mechanistically, we found that the C-terminal Cullin binding domain leads to oncogenic activity and the UBA domain acts as a negative regulator of DCUN1D1 function in NSCLC. Moreover, DCUN1D1 activated the FAK oncogenic signaling pathway and up-regulated PD-L1. Taken together, our results demonstrate that DCUN1D1 is a metastasis regulator and suggest a new therapeutic option for NSCLC metastasis.

Piperidinyl Ureas Chemically Control Defective in Cullin Neddylation 1 (DCN1)-Mediated Cullin Neddylation

We previously discovered and validated a class of piperidinyl ureas that regulate defective in cullin neddylation 1 (DCN1)-dependent neddylation of cullins. Here, we report preliminary structure-activity relationship studies aimed at advancing our high-throughput screen hit into a tractable tool compound for dissecting the effects of acute DCN1-UBE2M inhibition on the NEDD8/cullin pathway. Structure-enabled optimization led to a 100-fold increase in biochemical potency and modestly increased solubility and permeability as compared to our initial hit. The optimized compounds inhibit the DCN1-UBE2M protein-protein interaction in our TR-FRET binding assay and inhibit cullin neddylation in our pulse-chase NEDD8 transfer assay. The optimized compounds bind to DCN1 and selectively reduce steady-state levels of neddylated CUL1 and CUL3 in a squamous cell carcinoma cell line. Ultimately, we anticipate that these studies will identify early lead compounds for clinical development for the treatment of lung squamous cell carcinomas and other cancers.

Discovery of an Orally Bioavailable Inhibitor of Defective in Cullin Neddylation 1 (DCN1)-Mediated Cullin Neddylation

We previously reported the discovery, validation, and structure-activity relationships of a series of piperidinyl ureas that potently inhibit the DCN1-UBE2M interaction. We demonstrated that compound 7 inhibits both the DCN1-UBE2M protein-protein interaction and DCN1-mediated cullin neddylation in biochemical assays and reduces levels of steady-state cullin neddylation in a squamous carcinoma cell line harboring DCN1 amplification. Although compound 7 exhibits good solubility and permeability, it is rapidly metabolized in microsomal models (CL_int = 170 mL/min/kg). This work lays out the discovery of an orally bioavailable analogue, NAcM-OPT (67). Compound 67 retains the favorable biochemical and cellular activity of compound 7 but is significantly more stable both in vitro and in vivo. Compound 67 is orally bioavailable, well tolerated in mice, and currently used to study the effects of acute pharmacologic inhibition of the DCN1-UBE2M interaction on the NEDD8/CUL pathway.

Expression of DCUN1D1 in laryngeal squamous cell carcinoma and its inhibiting effect on TU-177 cells after interfered by RNA

Expression of DCUN1D1 in laryngeal squamous cell carcinoma (LSCC) and its inhibition by small interfering RNA (siRNA) target in the TU-177 cells was investigated. Immunohistochemistry was used to detect the expression level of DCUN1D1 in LSCC tissue in 140 cases and to analyze its relationship with clinical pathological characteristics. siRNA expression plasmid targeting DCUN1D1 was constructed and transferred into TU-177 cells. The effect of siRNA target DCUN1D1 gene silencing on proliferation, invasion and migration of TU-177 cells were observed by MTS assay and Transwell experiment. The expression levels of focal adhesion kinase (FAK) and matrix metalloproteinase-2(MMP-2) were detected by western blot. Expression level of DCUN1D1 protein increased significantly in T3 + T4, N+, and III + IV stages of LSCC patients (P < .05). After DCUN1D1 was targeted by siRNA, the DCUN1D1 protein level decreased 67% in siRNA-3 group, where average absorbance value was lower than the control and blank group with significant difference(F = 6.076, P < .05) in MTS assay, meantime migration, and invasion cells in each vision were the same (F = 19.851, F = 25.454, P < .01) in the Transwell experiment. The expression level of FAK and MMP-2 was significantly down-regulated in siRNA-3 group (F = 28.896, F = 40.240, P < .01). DCUN1D1 is associated with progression and prognosis of LSCC. After siRNA based target on DCUN1D1, TU-177 cells growth was inhibited and invasion of malignant tumour was diminished by reducing the expression of FAK and MMP-2. DCUN1D1 is could become a potential new target for the treatment of LSCC.

MicroRNA-195 inhibits growth and invasion of laryngeal carcinoma cells by directly targeting DCUN1D1

MicroRNAs (miRNAs) are a class of small, non-coding RNAs that regulate gene expression and are involved in cell biological processes. The aberrant expression of miR-195 has been found in various types of human cancer. However, the effect of miR-195 on the initiation and development of laryngeal squamous cell carcinoma (LSCC) remains to be elucidated. Accordingly, in the present study, we detected the expression level of miR-195 in the LSCC and the normal tissues and found that miR-195 were significantly downregulated in the LSCC tissues. Gain-of-function or loss-of-function studies including cell proliferation, wound healing assay, Transwell assay, cell cycle and apoptosis assays were performed to investigate the biological function of miR-195. Luciferase reporter assay and the rescue study confirmed that DCUN1D1 was a target of miR-195. Furthermore, DCUN1D1 expression levels were found to be upregulated in laryngeal tissues and to have a negative correlation with miR-195. We also found that both miR-195 and DCUN1D1 siRNAs can inhibit cell invasion possibly through downregulating Matrix metalloproteinase-2 (MMP-2) and Matrix metalloproteinase-9 (MMP-9) at the post-transcriptional level, which can be attenuated by restoring the expression of DCUN1D1. In summary, these data suggest that low expression of miR-195 contributes to the poor prognosis of LSCC and miR-195 regulates the proliferation and invasion ability of LSCC cells in vitro. miR-195 may suppress growth and invasion of LSCC cells possibly through targeting DCUN1D1, which would provide a candidate target for cancer therapy.

MicroRNA-520b Functions as a Tumor Suppressor in Colorectal Cancer by Inhibiting Defective in Cullin Neddylation 1 Domain Containing 1 (DCUN1D1)

MicroRNAs (miRs), a class of small noncoding RNAs, are important regulators for gene expression through directly binding to the 3′-untranslated region (3′-UTR) of their target mRNA. Recently, downregulation of miR-520b has been observed in several common human cancers. However, the exact role of miR-520b in colorectal cancer (CRC) has not previously been studied. In this study, our data showed that miR-520b was significantly downregulated in CRC and cell lines when compared with adjacent normal tissues and a normal intestinal epithelial cell line. Low expression of miR-520b was notably associated with the malignant progress and a shorter survival time for CRC patients. Restoration of miR-520b inhibited cell proliferation, migration, invasion, and epithelial–mesenchymal transition (EMT) in CRC cells. Defective in cullin neddylation 1 domain containing 1 (DCUN1D1) was then identified as a novel target gene of miR-520b in CRC cells. The expression of DCUN1D1 was significantly increased in CRC, with a negative correlation to miR-520b expression in CRC tissues. Moreover, a high expression of DCUN1D1 was significantly associated with the malignant progress and a poor prognosis for CRC patients. Furthermore, overexpression of DCUN1D1 rescued the miR-520b-mediated malignant phenotypes and EMT in CRC cells. The data demonstrate that miR-520b functions as a tumor suppressor in CRC through targeting DCUN1D1, suggesting that miR-520b may become a potential therapeutic target for the treatment of CRC.

MDM2 phenotypic and genotypic profiling, respective to TP53 genetic status, in diffuse large B-cell lymphoma patients treated with rituximab-CHOP immunochemotherapy: a report from the International DLBCL Rituximab-CHOP Consortium Program

MDM2 is a key negative regulator of the tumor suppressor p53, however, the prognostic significance of MDM2 overexpression in diffuse large B-cell lymphoma (DLBCL) has not been defined convincingly. In a p53 genetically-defined large cohort of de novo DLBCL patients treated with rituximab, cyclophosphamide, hydroxydaunorubicin, vincristine, and prednisone (R-CHOP) chemotherapy, we assessed MDM2 and p53 expression by immunohistochemistry (n = 478), MDM2 gene amplification by fluorescence in situ hybridization (n = 364), and a single nucleotide polymorphism in the MDM2 promoter, SNP309, by SNP genotyping assay (n = 108). Our results show that MDM2 overexpression, unlike p53 overexpression, is not a significant prognostic factor in overall DLBCL. Both MDM2 and p53 overexpression do not predict for an adverse clinical outcome in patients with wild-type p53 but predicts for significantly poorer survival in patients with mutated p53. Variable p53 activities may ultimately determine the survival differences, as suggested by the gene expression profiling analysis. MDM2 amplification was observed in 3 of 364 (0.8%) patients with high MDM2 expression. The presence of SNP309 did not correlate with MDM2 expression and survival. This study indicates that evaluation of MDM2 and p53 expression correlating with TP53 genetic status is essential to assess their prognostic significance and is important for designing therapeutic strategies that target the MDM2-p53 interaction.

Immunohistochemical Expression of DCUN1D1 in Non-small Cell Lung Carcinoma: Its Relation to Brain Metastasis

PURPOSE

Non-small cell lung carcinoma (NSCLC) comprises 75-85% of all lung cancers, and approximately 25% of all NSCLC patients develop brain metastasis. There are no reliable markers for predicting in which patients this metastasis will occur. DCUN1D1, also known as squamous cell carcinoma-related oncogene, is associated with tumor progression and poor outcomes in NSCLC. The objective of this study was to investigate the role of DCUN1D1 expression in cases of brain metastasis due to NSCLC.

MATERIALS AND METHODS

Primary tumor samples from a total of 71 cases of NSCLC, either with (n=40) or without (n=31) brain metastasis, were evaluated for DCUN1D1 expression by immunohistochemistry analysis.

RESULTS

DCUN1D1 expression was detected in 16 patients (23%) and tended to correlate with T classification (15% of T1-2 tumors vs. 30% of T3-4 tumors, p=0.083). DCUN1D1 expression was significantly associated with tumor stage. It was observed in none of the patients with stage I disease, 10% of those with stage II disease, and 29% with stage III disease (p=0.009). In addition, 14 of 16 DCUN1D1-positive patients resulted in brain metastasis (p=0.01). The odds ratio of brain metastasis for patients with DCUN1D1 expression was 3.112 (p=0.009).

CONCLUSION

DCUN1D1 expression may play a role in tumor progression and development of brain metastasis in patients with NSCLC. Evaluation of DCUN1D1 expression may provide assistance in identifying those patients who are at higher risk for brain metastasis.

SCCRO promotes glioma formation and malignant progression in mice

Originally identified as an oncogene activated by amplification in squamous cell carcinomas, several lines of evidence now suggest that squamous cell carcinoma-related oncogene (SCCRO; aka DCUN1D1) may play a role in the pathogenesis of a wide range of human cancers including gliomas. SCCRO's oncogenic function is substantiated by its ectopic expression, resulting in transformation of cells in culture and xenograft formation in nude mice. The aim of this study was to assess the in vivo oncogenicity of SCCRO in a murine model. Ubiquitous expression of SCCRO resulted in early embryonic lethality. Because SCCRO overexpression was detected in human gliomas, its in vivo oncogenic activity was assessed in an established murine glioma model. Conditional expression of SCCRO using a replication-competent ASLV long terminal repeat with splice acceptor/nestin-(tumor virus-A) tv-a model system was not sufficient to induce tumor formation in a wild-type genetic background, but tumors formed with increasing frequency and decreasing latency in facilitated background containing Ink4a deletion alone or in combination with PTEN loss. Ectopic expression of SCCRO in glial progenitor cells resulted in lower-grade gliomas in Ink4a(-/-) mice, whereas its expression in Ink4a(-/-)/PTEN(-/-) background produced high-grade glioblastoma-like lesions that were indistinguishable from human tumors. Expression of SCCRO with platelet-derived growth factor-beta (PDGF-beta) resulted in an increased proportion of mice forming glioblastoma-like tumors compared with those induced by PDGF-beta alone. This work substantiates SCCRO's function as an oncogene by showing its ability to facilitate malignant transformation and carcinogenic progression in vivo and supports a role for SCCRO in the pathogenesis of gliomas and other human cancers.

SOX2 is an oncogene activated by recurrent 3q26.3 amplifications in human lung squamous cell carcinomas

Squamous cell carcinoma (SCC) of the lung is a frequent and aggressive cancer type. Gene amplifications, a known activating mechanism of oncogenes, target the 3q26-qter region as one of the most frequently gained/amplified genomic sites in SCC of various types. Here, we used array comparative genomic hybridization to delineate the consensus region of 3q26.3 amplifications in lung SCC. Recurrent amplifications occur in 20% of lung SCC (136 tumors in total) and map to a core region of 2 Mb (Megabases) that encompasses SOX2, a transcription factor gene. Intense SOX2 immunostaining is frequent in nuclei of lung SCC, indicating potential active transcriptional regulation by SOX2. Analyses of the transcriptome of lung SCC, SOX2-overexpressing lung epithelial cells and embryonic stem cells (ESCs) reveal that SOX2 contributes to activate ESC-like phenotypes and provide clues pertaining to the deregulated genes involved in the malignant phenotype. In cell culture experiments, overexpression of SOX2 stimulates cellular migration and anchorage-independent growth while SOX2 knockdown impairs cell growth. Finally, SOX2 over-expression in non-tumorigenic human lung bronchial epithelial cells is tumorigenic in immunocompromised mice. These results indicate that the SOX2 transcription factor, a major regulator of stem cell function, is also an oncogene and a driver gene for the recurrent 3q26.33 amplifications in lung SCC.