Abstract 1513: A multi-sample study reveals the evolution and heterogeneity in high-grade serous ovarian cancer

Ovarian cancer is a heterogeneous disease and high-grade serous carcinoma (HGSC) accounts for 70% of them. The pathogenesis of HGSC had remained obscure until the identification of its tubal origin; however, the carcinogenesis process remains largely underexplored. Meanwhile, targeted therapy using poly(ADP-ribose) polymerase (PARP) inhibitors have revolutionized the treatment of HGSCs and emphasizes the importance of patient stratification. Nonetheless, current clinical trials use different assays and a consensus approach for patient stratification is still lacking.

In this study, whole genome sequencing technique was used to profile tumor-normal sample pairs, including some related tumors collected from different anatomical sites. This yields a multi-sample cohort comprising 55 pre-treatment samples from 33 HGSC patients and is suitable for addressing questions about molecular stratification and tumor pathogenesis.

We first recapitulated two reported HGSC subgroups (H-HRD and H-FBI) in our cohort. Comprehensive analyses were conducted on genomic scars ranging from mutations, indels, structural variants and copy numbers. Our data suggests that the genomic subgroups are characterized by different extent and onset timing of homologous recombination repair defect (HRD) as well as CCNE1 activation. Of note, H-HRD group showed higher levels of copy number-based HRD score, which often serves as a surrogate biomarker for PARP inhibitor treatment response.

On the other hand, tumor evolutionary trajectory was reconstructed based on in silico methods capable of inferring relative timing of genetic alterations. This highlights an early bifurcation of carcinogenesis paths in this HGSC dichotomy, despite a common scenario of a very early TP53 mutation, an often early whole genome duplication and a chromosomal instability phenotype seen eventually.

Overall, these findings corroborate the concept of tumor-intrinsic genomic phenotypes by providing mechanistic underpinnings from the aspect of tumor evolution. This provides the rationale for studying HGSC disease biology in different contexts and formulating questions about subtype-specific pathogenesis and vulnerabilities. Translationally, it also holds the promise for better identifying the patient subset that might benefit from PARP inhibitor treatment.

Citation Format: Siao-Han Wong, Kai Doberstein, Frederik Marmé, Benedikt Brors. A multi-sample study reveals the evolution and heterogeneity in high-grade serous ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1513.

LINE-1 ORF1p as a candidate biomarker in high grade serous ovarian carcinoma

Long interspersed element 1 (LINE-1) open reading frame 1 protein (ORF1p) expression is a common feature of many cancer types, including high-grade serous ovarian carcinoma (HGSOC). Here, we report that ORF1p is not only expressed but also released by ovarian cancer and primary tumor cells. Immuno-multiple reaction monitoring-mass spectrometry assays showed that released ORF1p is confidently detectable in conditioned media, ascites, and patients' plasma, implicating ORF1p as a potential biomarker. Interestingly, ORF1p expression is detectable in fallopian tube (FT) epithelial precursors of HGSOC but not in benign FT, suggesting that ORF1p expression in an early event in HGSOC development. Finally, treatment of FT cells with DNA methyltransferase inhibitors led to robust expression and release of ORF1p, validating the regulatory role of DNA methylation in LINE-1 repression in non-tumorigenic tissue.

Abstract B27: Cellular retinoic acid binding protein 2 (CRABP2) is a novel biomarker and potential therapeutic target for high-grade serous ovarian carcinomas

Ovarian cancer ranks fifth in cancer deaths among women in the United States, accounting for more deaths than any other gynecologic cancer. There is an unmet medical need for biomarkers that can detect high-grade serous ovarian carcinoma (HGSOC) at an early stage. Our laboratory evaluated the biomarker potential of cellular retinoic acid binding protein 2 (CRABP2). Using Western blots (WB) and immunohistochemistry (IHC), we show that CRABP2 is expressed and secreted by HGSOC cells and tissues and is absent in normal fallopian tube (FT) epithelium. CRABP2 expression was associated with poor overall survival in patients with HGSOC. Proteomic analyses quantified specific secretion of CRABP2 in conditioned media from HGSOC cell lines, primary ascites-derived tumor cells, and serum from HGSOC patients. Expression of CRABP2 was positively associated with CRABP2 copy number amplifications by mining The Cancer Genome Atlas database. In addition, DNA methylation studies identified a putative enhancer downstream of CRABP2 that is hyper-methylated in fallopian tube epithelia (FTE) tissue and hypomethylated in HGSOC cells and tissues that expressed CRABP2. Inhibition of DNA methylation with DNA methytransferase (DNMT) inhibitors resulted in robust expression of CRABP2 protein in FT cell lines. Finally, a finding supported by CRABP2 knockdown experiments showed that CRABP2 loss triggers cell death in HGSOC cell lines. In conclusion, CRABP2 may serve as a novel biomarker for HGSOC with clinical potential as a therapeutic target.

Citation Format: Yi Feng, Michael Gillette, Eric Kuhn, David Klinkebiel, Marilyn A. Mitchell, Kai Doberstein, Daniele Chaves-Moreira, Sho Sato, Haineng Xu, Brett Bomwell, Michelle S. Hirsch, Carolina Reyes, Adam R. Karpf, Michael J. Birrer, Steven J. Skates, Steven A. Carr, Ronny Drapkin. Cellular retinoic acid binding protein 2 (CRABP2) is a novel biomarker and potential therapeutic target for high-grade serous ovarian carcinomas [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research; 2019 Sep 13-16, 2019; Atlanta, GA. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(13_Suppl):Abstract nr B27.

Abstract 1065: Comprehensive molecular and experimental characterization of ovarian clear cell carcinoma cell lines for in vivo drug development

Purpose: Ovarian cancer is heterogeneous with multiple histological subtypes and a wide range of genetic aberrations. While high-grade serous ovarian carcinoma (HGSOC) is the most common, clear cell ovarian carcinoma (CCOC) is the most challenging to treat and exhibits low response rates to standard therapies. However, efforts to understand CCOC and develop new therapies have been limited because it represents a minority of ovarian cancers in the U.S. and Europe. In contrast, CCOC accounts for approximately 30% of all ovarian cancer in Japan. To improve the survival of patients with CCOC, a deeper understanding of the molecular features that define available model systems is needed. Our goal is to comprehensively characterize a panel of CCOC lines using next generation sequencing and functional in vitro and in vivo experiments to define the lines that are most faithful to CCOC and are tractable for subsequent in vivo drug discovery.

Method: We obtained 9 CCOC cells from ATCC, Riken Cell Bank, and University of Miami (ES-2, TOV21G, OVTOKO, OVMANA, OCI-C5x, JHOC-5, JHOC-7, JHOC-9, and OVISE). Genomic DNA, RNA, and protein were isolated and subjected to whole exome DNA-seq, RNA-seq, and reverse phase protein array (RPPA), respectively. We performed in vitro MTT assays to test the sensitivity of these lines to chemotherapies. Tumorigenicity was evaluated by injecting 5 million cells of luciferized CCOC lines into NSG female mice using both the subcutaneous route and the intraperitoneal route. Imaging was performed weekly using the In Vivo Imaging System.

Results: ARID1A mutation, the most prevalent mutation in CCOC, is present in 8 of the 9 cell lines (TOV21G, OVTOKO, OVMANA, OCI-C5x, JHOC-5, JHOC-7, JHOC-9, and OVISE), whereas the second common mutation in CCOC (PIK3CA) is detected in 5 lines (TOV21G, OVMANA, OCI-C5x, JHOC-7, and OVISE). The ES-2 cell line has both TP53 and BRAF mutations and its genomic profile is not typical of CCOC. Principal component analysis of RPPA showed distinct groups between the 9 CCOC lines and the 6 HGSOC lines. Interestingly, we also observed two distinct clusters within the CCOC lines. Consistent with our genomic analysis, the ES-2 cell line correlated more closely with the HGSOC lines based on RPPA data. In our in vitro drug studies, OVTOKO and OCI-C5x exhibited resistance to Carboplatin/Paclitaxel. In xenograft study, 4 cell lines (ES-2, TOV21G, OVTOKO, and OCI-C5x) formed measurable tumor within a month. In contrast, OVMANA, JHOC-7, JHOC-9, and OVISE took over 100 days to form tumors.

Conclusion: Our data suggests that there may exist two functionally distinct groups within CCOC that warrants further study. In vitro and in vivo studies identified 4 cell lines that represent tractable models for rigorous therapeutic studies: ES-2, TOV21G, OVTOKO, and OCI-C5x. However, ES-2 appears to cluster more closely with HGSOC and may not represent the CCOC histotype.

Citation Format: Yasuto Kinose, Dorothy Hallberg, Kai Doberstein, Gordon Mills, Tan Ince, Victor Velculescu, Fiona Simpkins, Ronny Drapkin. Comprehensive molecular and experimental characterization of ovarian clear cell carcinoma cell lines for in vivo drug development [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1065.

Critical questions in ovarian cancer research and treatment: Report of an American Association for Cancer Research Special Conference

Substantial progress has been made in understanding ovarian cancer at the molecular and cellular level. Significant improvement in 5-year survival has been achieved through cytoreductive surgery, combination platinum-based chemotherapy, and more effective treatment of recurrent cancer, and there are now more than 280,000 ovarian cancer survivors in the United States. Despite these advances, long-term survival in late-stage disease has improved little over the last 4 decades. Poor outcomes relate, in part, to late stage at initial diagnosis, intrinsic drug resistance, and the persistence of dormant drug-resistant cancer cells after primary surgery and chemotherapy. Our ability to accelerate progress in the clinic will depend on the ability to answer several critical questions regarding this disease. To assess current answers, an American Association for Cancer Research Special Conference on "Critical Questions in Ovarian Cancer Research and Treatment" was held in Pittsburgh, Pennsylvania, on October 1-3, 2017. Although clinical, translational, and basic investigators conducted much of the discussion, advocates participated in the meeting, and many presentations were directly relevant to patient care, including treatment with poly adenosine diphosphate ribose polymerase (PARP) inhibitors, attempts to improve immunotherapy by overcoming the immune suppressive effects of the microenvironment, and a better understanding of the heterogeneity of the disease.

Abstract PR01: Cyclin E: Targeting cell cycle dependencies in CCNE1-amplified tumors

Genomic instability is a hallmark of high-grade serous ovarian carcinoma (HGSOC). Based on The Cancer Genome Atlas (TCGA), it is estimated that approximately 50% of HGSOCs harbor a defect in the homologous recombination (HR) pathway of DNA repair. In contrast, the 20% that harbor CCNE1 amplifications appear to have an intact HR pathway. These tumors are associated with shorter overall survival and resistance to platinum-based chemotherapy. Cyclin E is the activating partner of cyclin-dependent kinase 2 (CDK2), which controls cell cycle progression from G1 to S phase.

Our previous data showed that CCNE1 amplification and overexpression occurs early in serous tumorigenesis. Importantly, in immortalized human fallopian tube secretory epithelial cells (FTSEC), constitutive Cyclin E overexpression imparts malignant characteristics to these cells. This leads to an accumulation of DNA damage and altered gene expression of genes involved in DNA replication and fork protection. However, in the setting of hTERT expression and a p53 mutant, Cyclin E overexpression alone was not capable of fully transforming the FTSECs. Therefore, in order to identify cooperating genetic alterations, we performed an in vitro gain-of-function (GOF) screen. One of those identified hits was the RAD51 paralog XRCC2, which is known to be involved in the homologous recombination DNA repair pathway and in fork protection. We could show that XRCC2 expression is upregulated in response to Cyclin E overexpression in FTSECs and when analyzing the TCGA patient cohorts, we found a strong correlation between RNAseq expression of XRCC2 and Cyclin E. We could further demonstrate that the knockdown of XRCC2 is synthetic lethal in CCNE1 amplified ovarian cancer cell lines but not in cells that harbor no CCNE1 amplification, indicating that the upregulation of XRCC2 creates a dependency in CCNE1-amplified tumors.

Since overexpression of Cyclin E leads to unscheduled S-phase entry and stress on the replication fork, we speculated that one of the roles of XRCC2 might be to stabilize the replication fork in CCNE1-overexpressing cells. We found that the knockdown of XRCC2 in Cyclin E-overexpressing cells leads to a strong reduction in fork speed and fork recovery.

To further understand this mechanism we analyzed the binding partners of XRCC2 in CCNE1 amplified cells by mass spectrometry. Interestingly, we found that XRCC2 interacts with the minichromosome maintenance deficient 7 (MCM7) protein. MCM7 is part of the MCM complex that unwinds the DNA during replication. Surprisingly, the downregulation XRCC2 also led to a strong reduction in MCM7 protein expression, indicating that XRCC2 may play an important role in stabilization of the MCM complex. This is especially interesting since CCNE1-amplified cells are more dependent on active MCM complexes and are more sensitive to MCM complex reduction compared to normal cells. Further defining the factors that contribute to the XRCC2-MCM7 interaction at the replication fork may define novel vulnerabilities in CCNE1-amplified tumors.

This abstract is also being presented as Poster A03.

Citation Format: Kai Doberstein, Alison Karst, Paul T. Kroeger, Jr., Paul Jones, William Hahn, Ronny Drapkin. Cyclin E: Targeting cell cycle dependencies in CCNE1-amplified tumors. [abstract]. In: Proceedings of the AACR Conference: Addressing Critical Questions in Ovarian Cancer Research and Treatment; Oct 1-4, 2017; Pittsburgh, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(15_Suppl):Abstract nr PR01.

Abstract B42: The cell adhesion molecule, L1CAM, is important for the dissemination and metastasis of fallopian tube precursor lesions

One of the hallmarks during the progression of high-grade serous ovarian cancer (HGSOC) is the dissemination and metastasis of cells from fallopian tube precursor lesions, namely serous tubal in situ carcinoma (STIC), to other sites of the fallopian tube, ovary, or peritoneal cavity.

We, and others, have previously demonstrated that HGSOC originates from benign-appearing lesions in the fallopian tube, harboring TP53 mutations (P53 signatures), that progress into STIC lesions, and show an increase in DNA damage and proliferation. While studies have analyzed those precursor lesions at the distal end of the fallopian tube, little is known about the mechanism that triggers the dissemination of cells from fallopian tube precursor lesions to other sites.

The L1 cell adhesion molecule (L1CAM, CD171) has been shown to play an important role in many types of cancer, including ovarian carcinoma. In vitro studies have shown that L1CAM enhances proliferation, cell migration, epithelial-to-mesenchymal transition (EMT), and chemoresistance in ovarian carcinoma cells. In HGSOC, high expression of L1CAM is associated with poor overall survival and confers chemoresistance in this setting. It was further shown that L1CAM expression and the presence of its soluble form in ovarian carcinoma patient ascites correlates with shorter patient survival.

Current knowledge is limited on the role of L1CAM during the initiation or the early stages of HGSOC. Therefore, we investigated precursor STIC lesions for L1CAM expression. We found expression of L1CAM in most of the analyzed STIC lesions, but also in scattered normal fallopian epithelial cells. Interestingly, the expression in STIC lesions was not homogenous but showed a gradient with its lowest expression in cells attached to the basement membrane and its highest expression in pseudo-stratified cells that appear to be in the process of detaching.

To investigate whether L1CAM contributes to detachment, we used the CRISPR/CAS9 system to knock down L1CAM in the ovarian cancer cell line OVCAR8. Importantly, the knockdown of L1CAM decreased the ability of cells to grow and survive under anchorage-independent culture conditions and to build 3-dimensional spheres. Conversely, overexpression of L1CAM in primary fallopian tube cells led to a strong increase in their ability to form spheres.

We found that the expression of L1CAM in ovarian cancer and primary fallopian tube cell lines led to an increase in integrin alpha-5 and integrin beta-1 expression. This ultimately leads to an increased recruitment and organization of fibronectin and assembly of a basement membrane under anchorage-independent culture conditions. These data indicate that in precursor lesions L1CAM expression may be necessary for the tumor to disseminate and metastasize to other sites of the fallopian tube, ovary, or peritoneal cavity.

Finally, we found a strong link between the noncanonical WNT pathway and L1CAM expression, which might explain the high L1CAM expression at the apical side of the STIC lesions. However, further studies must be performed to analyze which factors regulate the expression gradient of L1CAM and whether the inhibition of those factors or L1CAM itself delay the onset of the malignant disease.

Citation Format: Kai Doberstein, Marcin Iwanicki, Mina Fogel, Peter Altevogt, Ronny Drapkin. The cell adhesion molecule, L1CAM, is important for the dissemination and metastasis of fallopian tube precursor lesions. [abstract]. In: Proceedings of the AACR Conference: Addressing Critical Questions in Ovarian Cancer Research and Treatment; Oct 1-4, 2017; Pittsburgh, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(15_Suppl):Abstract nr B42.

Abstract 1425: Targeting cell cycle dependencies in CCNE1 amplified tumors

Genomic instability is a hallmark of high grade serous ovarian carcinoma (HGSOC). Based on The Cancer Genome Atlas (TCGA), it is estimated that approximately 50% of HGSOCs harbor a defect in the homologous recombination (HR) pathway of DNA repair. In contrast, the 20% that harbor CCNE1 amplifications appear to have an intact HR pathway. These tumors are associated with shorter overall survival and resistance to chemotherapy. Cyclin E is the activating partner of cyclin-dependent kinase 2 (CDK2) which controls cell cycle progression from G1 to S phase. Our previous data showed that CCNE1 amplification and overexpression occurs early in serous tumorigenesis. Importantly, in immortalized human fallopian tube secretory epithelial cells (FTSEC), constitutive Cyclin E overexpression imparts malignant characteristics to these cells. This leads to an accumulation of DNA damage and altered gene expression of genes involved in DNA replication and fork protection. However, in the setting of hTERT expression and a p53 mutant, Cyclin E overexpression alone was not capable of fully transforming the FTSECs. Therefore, in order to identify cooperating genetic alterations, we performed an in vitro gain-of-function (GOF) screen. One of those identified hits was the RAD51 paralog XRCC2, which is known to be involved in the HR DNA repair pathway and in fork protection. We could show that XRCC2 expression is upregulated in response to Cyclin E overexpression in FTSECs and we found a strong correlation between RNAseq expression of XRCC2 and Cyclin E in the TCGA patient cohorts. We could further demonstrate that the knock down of XRCC2 is synthetic lethal in CCNE1 amplified ovarian cancer cell lines but not in cells that harbor no CCNE1 amplification, indicating that the upregulation of XRCC2 creates a dependency in CCNE1 amplified tumors. Since overexpression of Cyclin E leads to unscheduled S-phase entry and stress on the replication fork, we speculated that one of the roles of XRCC2 might be to stabilize the replication fork in Cyclin E overexpressing cells. We found that the knock down of XRCC2 in Cyclin E overexpressing cells leads to a strong reduction in fork speed and fork recovery. To further understand this mechanism we analyzed the binding partners of XRCC2 in CCNE1 amplified cells by mass spectrometry. Interestingly, we found that XRCC2 interacts with the minichromosome maintenance deficient 7 (MCM7) protein. MCM7 is part of the MCM complex that unwinds the DNA during replication. Surprisingly, the downregulation XRCC2 also led to a strong reduction in MCM7 protein expression indicating that XRCC2 may play an important role in stabilization the MCM complex. This is especially interesting since CCNE1 amplified cells are more dependent on active MCM complexes and are more sensitive to MCM complex reduction compared to normal cells. Further defining the factors that contribute to the XRCC2-MCM7 interaction at the replication fork may define novel vulnerabilities in CCNE1 amplified tumors.

Citation Format: Kai Doberstein, Alison Karst, Paul Jones, Azra Ligon, Michelle Hirsch, Dariush Etemadmoghadam, William Hahn, David Bowtell, Ronny Drapkin. Targeting cell cycle dependencies in CCNE1 amplified tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1425. doi:10.1158/1538-7445.AM2017-1425

Abstract PR05: Identifying potential targets in Cyclin E-amplified tumors

Genomic instability is a hallmark of high grade serous ovarian carcinoma (HGSOC). Based on The Cancer Genome Atlas (TCGA), it is estimated that approximately 50% of HGSOCs harbour a defect in the homologous recombination (HR) pathway of DNA repair. A majority of these cases are due to the germline and/or somatic inactivation of the BRCA1 or BRCA2 genes. In contrast, the 20% of HGSOC that harbor CCNE1 amplifications are mutually exclusive with BRCA mutations and appear to have an intact HR pathway. These tumors are associated with shorter overall survival and resistance to platinum-based chemotherapy. Cyclin E is the activating partner of cyclin-dependent kinase 2 (CDK2) which controls cell cycle progression through phosphorylation of pRB and induction of E2F transcriptional activity.

Our previous data showed that CCNE1 amplification and overexpression occurs early in serous tumorigenesis. Importantly, in immortalized human fallopian tube secretory epithelial cells (FTSEC), constitutive cyclin E overexpression imparts malignant characteristics to these cells, including increased proliferation, loss of contact inhibition and clonogenicity. This leads to an accumulation of DNA damage and altered gene expression of genes involved in DNA replication fork protection and the BRCA-Fanconi Anemia pathway. However, in the setting of hTERT expression and a p53 mutant, Cyclin E overexpression alone was not capable of fully transforming the FTSECs. Therefore, in order to identify cooperating genetic alterations, we performed an in vitro gain-of-function (GOF) screen using an open reading frame (ORF) library of approximately 800 genes that are recurrently amplified in HGSOC. The transduced cells were then tested for anchorage independent colony formation on ultra-low attachment (ULA) plates and soft agar. A total of 92 genes were identified between the two assays, with 28 genes registering as a “hit” in both assays. A subset was then retested for in vivo growth in immunocompromised mice using the empty vector as the negative control. Positive hits included CHD2, GAB2, AKT, PITRM1, PTPRB, XRCC2, PSME4, and SLC38A1.

Interestingly, by using RNA interference we found that knock-down of some of the genes found in the GOF screen is synthetic lethal in cancer cells that overexpress Cyclin E or have a CCNE1 amplification. The identified hits included genes involved in the DNA damage response pathways and the Fanconi Anemia pathway. Underlining the importance of these genes, analysis of the TCGA revealed that both pathways are strongly upregulated in Cyclin E overexpressing tumors. These results suggest that targeting cooperating genetic dependencies in CCNE1 amplified tumors may be a novel therapeutic avenue. We are currently using our panel of patient-derived tumor xenograft and cell lines to address this possibility.

This abstract is also presented as Poster A06.

Citation Format: Kai Doberstein, Alison Karst, Dariush Etemadmoghadam, Paul Jones, Gavin Dunn, William Hahn, David Bowtell, Ronny Drapkin. Identifying potential targets in Cyclin E-amplified tumors. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: Exploiting Vulnerabilities; Oct 17-20, 2015; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(2 Suppl):Abstract nr PR05.

L1CAM is expressed in triple-negative breast cancers and is inversely correlated with androgen receptor

Background

Breast cancer is a heterogeneous disease displaying distinct molecular features and clinical outcome. The molecular profile of triple-negative breast cancers (TNBCs) overlaps with that of basal-like breast cancers that in turn show similarities with high-grade serous ovarian and endometrial carcinoma. L1CAM is an established biomarker for the latter cancers and we showed before that approximately 18% of primary breast cancers are positive for L1CAM and have a bad prognosis. Here we analysed the expression of L1CAM breast cancer subtypes.

Methods

We analyzed mRNA and protein expression data from different breast cancer cohorts for L1CAM, estrogen receptor, progesterone receptor, Her-2 and Androgen receptor (AR) and correlated the data. We performed Western blot analysis on tumor cell lysates and carried out chromatin-immuno-precipitation (CHIP) after AR overexpression.

Results

We find that L1CAM is expressed preferentially though not exclusively in TNBCs. Using the human cancer genome atlas database and two independent breast cancer cohorts we find that L1CAM is inversely correlated with androgen receptor (AR) expression. We found that L1CAM^highAR^low primary breast tumors have the worst clinical outcome. Overexpression of AR in MDA-MB436 breast cancer cells decreased L1CAM expression at the protein and mRNA level and CHIP-analysis revealed binding of AR to the L1CAM promoter region.

Conclusions

These results suggest that L1CAM in breast cancer is under AR control. The data also strongly advocate the use of L1CAM assessment in breast cancer diagnosis. We suggest that L1CAM expression could be causally related to the bad prognosis of TNBCs.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-14-958) contains supplementary material, which is available to authorized users.

Paired box gene 8 (PAX8) expression is associated with sonic hedgehog (SHH)/wingless int (WNT) subtypes, desmoplastic histology and patient survival in human medulloblastomas

AIMS

The paired box gene 8 (PAX8) plays crucial roles in organ patterning and cellular differentiation during development and tumorigenesis. Although its function is partly understood in vertebrate development, there is poor data concerning human central nervous system (CNS) development and brain tumours.

METHODS

We investigated developing human (n = 19) and mouse (n = 3) brains as well as medulloblastomas (MBs) (n = 113) for PAX8 expression by immunohistochemistry. Human MB cell lines were assessed for PAX8 expression using polymerase chain reaction and immunoblotting and analysed for growth and migration following PAX8 knock-down by small interfering ribonucleic acid (siRNA).

RESULTS

PAX8 protein expression was associated with germinal layers in human and murine forebrain and hindbrain development. PAX8 expression significantly decreased over time in the external granule cell layer but increased in the internal granule cell layer. In MB subtypes, we observed an association of PAX8 expression with sonic hedgehog (SHH) and wingless int subtypes but not with group 3 and 4 MBs. Beyond that, we detected high PAX8 levels in desmoplastic MB subtypes. Univariate analyses revealed high PAX8 levels as a prognostic factor associated with a significantly better patient prognosis in human MB (overall survival: Log-Rank P = 0.0404, Wilcoxon P = 0.0280; progression-free survival: Log-Rank P = 0.0225; Wilcoxon P = 0.0136). In vitro assays revealed increased proliferation and migration of MB cell lines after PAX8 siRNA knock-down.

CONCLUSION

In summary, high PAX8 expression is linked to better prognosis in MBs potentially by suppressing both proliferative and migratory properties of MB cells. The distinct spatio-temporal expression pattern of PAX8 during brain development might contribute to the understanding of distinct MB subtype histogenesis.

The transcription factor PAX2 regulates ADAM10 expression in renal cell carcinoma

ADAM10 is a metalloprotease that plays an important role in the progression and metastasis of various cancers. In the present study, we present compelling evidence that PAX2 can bind to the promotor of ADAM10 and regulate ADAM10 protein expression in renal cancer cells. We further show that ADAM10 is the major sheddase for the constitutive cleavage of L1-CAM and c-Met, two important proteins involved in the progression of renal cancer. The downregulation of ADAM10 led to a more scattered cell phenotype, which was accompanied by the induction of Slug and the loss of E-cadherin, which is observed during epithelial-to-mesenchymal transition (EMT). In addition, the downregulation of ADAM10 reduced the proliferation but induced the migration of renal cancer cells. Notably, the downregulation of PAX2 led to an increased L1-CAM expression, which was accompanied by a massive metalloprotease-mediated release of soluble L1-CAM. Importantly, soluble L1-CAM induced the proliferation of endothelial cells and the migration of renal cancer cells. Finally, we can demonstrate that the silencing of PAX2 led to an L1-CAM-dependent activation of the PI3K/Akt pathway, one important pathway mediating cancer cell survival. In summary, we identified PAX2 as a regulator of L1-CAM and ADAM10, which play crucial roles in the progression of various cancers including renal cell carcinoma and the downregulation of ADAM10 maybe an earlier step in renal cancer development as it seems to be involved in processes of EMT.

PAX2 regulates ADAM10 expression and mediates anchorage-independent cell growth of melanoma cells

PAX transcription factors play an important role during development and carcinogenesis. In this study, we investigated PAX2 protein levels in melanocytes and melanoma cells by Western Blot and immunofluorescence analysis and characterized the role of PAX2 in the pathogenesis of melanoma. In vitro we found weak PAX2 protein expression in keratinocytes and melanocytes. Compared to melanocytes increased PAX2 protein levels were detectable in melanoma cell lines. Interestingly, in tissue sections of melanoma patients nuclear PAX2 expression strongly correlated with nuclear atypia and the degree of prominent nucleoli, indicating an association of PAX2 with a more atypical cellular phenotype. In addition, with chromatin immunoprecipitation assay, PAX2 overexpression and PAX2 siRNA we present compelling evidence that PAX2 can regulate ADAM10 expression, a metalloproteinase known to play important roles in melanoma metastasis. In human tissue samples we found co-expression of PAX2 and ADAM10 in melanocytes of benign nevi and in melanoma cells of patients with malignant melanoma. Importantly, the downregulation of PAX2 by specific siRNA inhibited the anchorage independent cell growth and decreased the migratory and invasive capacity of melanoma cells. Furthermore, the downregulation of PAX2 abrogated the chemoresistance of melanoma cells against cisplatin, indicating that PAX2 expression mediates cell survival and plays important roles during melanoma progression.

L1-CAM expression in ccRCC correlates with shorter patients survival times and confers chemoresistance in renal cell carcinoma cells

Conflicting data exist about the expression of L1 cell adhesion molecule (L1-CAM) in clear cell renal cell carcinoma (ccRCC). To determine the clinical usefulness of L1-CAM as a therapeutic or prognostic marker molecule in renal cancer patients, we analyzed its expression on a cohort of 282 renal cell carcinoma (RCC) patients. L1-CAM expression was found in 49.5% of 282 renal cancer tissues. Importantly, L1-CAM expression in patients with ccRCC was associated with significantly shorter patient survival time. We further present evidence that L1-CAM was involved in the resistance against therapeutic reagents like rapamycin, sunitinib and cisplatin. The downregulation of L1-CAM expression decreased renal cancer cell proliferation and reduced the expression of cyclin D1. In addition, we found out that Von Hippel-Lindau (VHL) deficiency was accompanied by a downregulation of the transcription factor PAX8 and L1-CAM. In normal renal tissue, PAX8 and L1-CAM were co-expressed in collecting duct cells. Importantly, the downregulation of PAX8 by small interfering RNA increased the expression of L1-CAM and concomitantly induced the migration of renal cancer cells. Furthermore, we observed in 65.3% of 282 RCC patients a downregulation of PAX8 expression. With chromatin immunoprecipitation analysis, we additionally demonstrate that PAX8 can bind to the promoter of L1-CAM and we further observed that the downregulation of PAX8 was accompanied by increased L1-CAM expression in a high fraction of ccRCC patients. In summary, we show that VHL and PAX8 are involved in the regulation of L1-CAM in renal cancer and L1-CAM represents an important therapeutic and prognostic marker protein for the treatment of ccRCC.

ADAM10 is expressed in human podocytes and found in urinary vesicles of patients with glomerular kidney diseases

Background

The importance of the Notch signaling in the development of glomerular diseases has been recently described. Therefore we analyzed in podocytes the expression and activity of ADAM10, one important component of the Notch signaling complex.

Methods

By Western blot, immunofluorescence and immunohistochemistry analysis we characterized the expression of ADAM10 in human podocytes, human urine and human renal tissue.

Results

We present evidence, that differentiated human podocytes possessed increased amounts of mature ADAM10 and released elevated levels of L1 adhesion molecule, one well known substrate of ADAM10. By using specific siRNA and metalloproteinase inhibitors we demonstrate that ADAM10 is involved in the cleavage of L1 in human podocytes. Injury of podocytes enhanced the ADAM10 mediated cleavage of L1. In addition, we detected ADAM10 in urinary podocytes from patients with kidney diseases and in tissue sections of normal human kidney. Finally, we found elevated levels of ADAM10 in urinary vesicles of patients with glomerular kidney diseases.

Conclusions

The activity of ADAM10 in human podocytes may play an important role in the development of glomerular kidney diseases.

CXCL16 and oxLDL are induced in the onset of diabetic nephropathy

Diabetic nephropathy (DN) is a major cause of end-stage renal failure worldwide. Oxidative stress has been reported to be a major culprit of the disease and increased oxidized low density lipoprotein (oxLDL) immune complexes were found in patients with DN. In this study we present evidence, that CXCL16 is the main receptor in human podocytes mediating the uptake of oxLDL. In contrast, in primary tubular cells CD36 was mainly involved in the uptake of oxLDL. We further demonstrate that oxLDL down-regulated alpha(3)-integrin expression and increased the production of fibronectin in human podocytes. In addition, oxLDL uptake induced the production of reactive oxygen species (ROS) in human podocytes. Inhibition of oxLDL uptake by CXCL16 blocking antibodies abrogated the fibronectin and ROS production and restored alpha(3) integrin expression in human podocytes. Furthermore we present evidence that hyperglycaemic conditions increased CXCL16 and reduced ADAM10 expression in podocytes. Importantly, in streptozotocin-induced diabetic mice an early induction of CXCL16 was accompanied by higher levels of oxLDL. Finally immunofluorescence analysis in biopsies of patients with DN revealed increased glomerular CXCL16 expression, which was paralleled by high levels of oxLDL. In summary, regulation of CXCL16, ADAM10 and oxLDL expression may be an early event in the onset of DN and therefore all three proteins may represent potential new targets for diagnosis and therapeutic intervention in DN.

CXCL16 is expressed in podocytes and acts as a scavenger receptor for oxidized low-density lipoprotein

Podocytes are a crucial cell type in the kidney and play an important role in the pathology of glomerular kidney diseases like membranous nephropathy (MN). The identification of new factors involved in the progression of glomerular kidney diseases is of great importance to the development of new strategies for the treatment of renal injury. Here we demonstrate that CXCL16 and ADAM10 are constitutively expressed in human podocytes in normal renal tissue. Proinflammatory cytokines like interferon-gamma and tumor necrosis factor-alpha induced the expression of cellular CXCL16 and the release of its soluble form from human podocytes. Using different metalloproteinase inhibitors, we provide evidence that ADAM10 is involved in the interferon-gamma- and tumor necrosis factor-alpha-induced shedding of CXCL16 from human podocytes. In addition, ADAM10 knockdown by siRNA significantly increased both CXCL16 levels and, surprisingly, its ADAM17-mediated release. Notably, targeting of CXCL16 in human podocytes both decreased the chemotaxis of CXCR6-expressing T cells and strongly reduced oxidized low-density lipoprotein uptake in human podocytes. Importantly, in kidney biopsies of patients with MN, increased glomerular CXCL16 expression was accompanied by high levels of oxidized low-density lipoprotein and decreased expression of ADAM10. In addition, we found increased glomerular ADAM17 expression in patients diagnosed with MN. In summary, we presume important roles for CXCL16, ADAM10, and ADAM17 in the development of MN, suggesting these proteins as new therapeutic targets in this glomerular kidney disease.

Gene expression of the human Torque Teno Virus isolate P/1C1

Torque Teno Virus (TTV) has been assigned to the floating genus Anellovirus. TTV ssDNA genomes have a size of 3.6 to 3.8 kb and display up to 30% nucleotide diversity. The pathogenic potential of TTV is under investigation. To address a putative link of pathogenicity with the observed sequence variations, the transcription profile of P/1C1 (genogroup 1) isolated from a patient diseased with a non A-G hepatitis was analysed. Four mRNAs were identified, which encoded the seven proteins ORF1, ORF1/1, ORF1/2, ORF2, ORF2/2, ORF3 and ORF4. Expression of the ORF1 protein and its splice variant ORF1/1 in cell culture was detected by an ORF1-specific antiserum. Analysis of N-terminal tagged P/1C1-encoded proteins revealed that ORF1, ORF1/1 and ORF1/2 were localised in the nucleoli, ORF3 and ORF4 resided in the nucleoplasm, ORF2/2 appeared either in the nucleoli or the whole nucleus while ORF2 was the only protein seen in the cytoplasm.

Novel Intra-Tissue Perfusion System for Culturing Thick Liver Tissue

Innovative scaffold fabrication, angiogenesis promotion, and dynamic tissue culture techniques have been utilized to improve delivery of media into the core of large tissue constructs in tissue engineering. We have developed here an intra-tissue perfusion (ITP) system, which incorporates an array of seven micron-sized needles as a delivery conduit, to improve mass transfer into the core of thick liver tissues slices (>>300 microm mass transport limit). The ITP system improves the uniformity and distribution of media throughout the tissue, resulting in improved cell viability over the static-cultured controls. The ITP-cultured thick liver slices also exhibit improved phase I and phase II metabolic functions and albumin and urea synthetic functions after 3-day culture, which is the minimal period required by the U.S. Food and Drug Administration (FDA) for studying drug-drug interaction. This ITP system can also be used for culturing other thick tissue constructs of larger dimensions for various in vitro and in vivo applications, including bridging integration of the in vitro cultured constructs into living host tissues.