Stephen J. Murphy

Imatinib mesylate inhibits the profibrogenic activity of TGF-β and prevents bleomycin-mediated lung fibrosis

Idiopathic pulmonary fibrosis is a progressive and fatal fibrotic disease of the lungs with unclear etiology. Prior efforts to treat idiopathic pulmonary fibrosis that focused on anti-inflammatory therapy have not proven to be effective. Recent insight suggests that the pathogenesis is mediated through foci of dysregulated fibroblasts driven by profibrotic cytokine signaling. TGF-beta and PDGF are 2 of the most potent of these cytokines. In the current study, we investigated the role of TGF-beta-induced fibrosis mediated by activation of the Abelson (Abl) tyrosine kinase. Our data indicate that fibroblasts respond to TGF-beta by stimulating c-Abl kinase activity independently of Smad2/3 phosphorylation or PDGFR activation. Moreover, inhibition of c-Abl by imatinib prevented TGF-beta-induced ECM gene expression, morphologic transformation, and cell proliferation independently of any effect on Smad signaling. Further, using a mouse model of bleomycin-induced pulmonary fibrosis, we found a significant inhibition of lung fibrosis by imatinib. Thus, Abl family members represent common targets for the modulation of profibrotic cytokine signaling.

Cell-Type-Specific Activation of PAK2 by Transforming Growth Factor β Independent of Smad2 and Smad3

ABSTRACT Transforming growth factor β (TGF-β) causes growth arrest in epithelial cells and proliferation and morphological transformation in fibroblasts. Despite the ability of TGF-β to induce various cellular phenotypes, few discernible differences in TGF-β signaling between cell types have been reported, with the only well-characterized pathway (the Smad cascade) seemingly under identical control. We determined that TGF-β receptor signaling activates the STE20 homolog PAK2 in mammalian cells. PAK2 activation occurs in fibroblast but not epithelial cell cultures and is independent of Smad2 and/or Smad3. Furthermore, we show that TGF-β-stimulated PAK2 activity is regulated by Rac1 and Cdc42 and dominant negative PAK2 or morpholino antisense oligonucleotides to PAK2 prevent the morphological alteration observed following TGF-β addition. Thus, PAK2 represents a novel Smad-independent pathway that differentiates TGF-β signaling in fibroblast (growth-stimulated) and epithelial cell (growth-inhibited) cultures.

Fibroblast growth factor receptor 2 translocations in intrahepatic cholangiocarcinoma

Patients with cholangiocarcinoma often present with locally advanced or metastatic disease. There is a need for effective therapeutic strategies for advanced stage cholangiocarcinoma. Recently, FGFR2 translocations have been identified as a potential target for tyrosine kinase inhibitor therapies. This study evaluated 152 cholangiocarcinomas and 4 intraductal papillary biliary neoplasms of the bile duct for presence of FGFR2 translocations by fluorescence in situ hybridization and characterized the clinicopathologic features of cases with FGFR2 translocations. Thirteen (10 women, 3 men; 8%) of 156 biliary tumors harbored FGFR2 translocations, including 12 intrahepatic cholangiocarcinomas (12/96; 13%) and 1 intraductal papillary neoplasm of the bile duct. Histologically, cholangiocarcinomas with FGFR2 translocations displayed prominent intraductal growth (62%) or anastomosing tubular glands with desmoplasia (38%). Immunohistochemically, the tumors with FGFR2 translocations frequently showed weak and patchy expression of CK19 (77%). Markers of the stem cell phenotype in cholangiocarcinoma, HepPar1 and CK20, were negative in all cases. The median cancer-specific survival for patients whose tumors harbored FGFR2 translocations was 123 months compared to 37 months for cases without FGFR2 translocations (P = .039). This study also assessed 100 cholangiocarcinomas for ERBB2 amplification and ROS1 translocations. Of the cases tested, 3% and 1% were positive for ERBB2 amplification and ROS1 translocation, respectively. These results confirm that FGFR2, ERRB2, and ROS1 alterations are potential therapeutic targets for intrahepatic cholangiocarcinoma.

Mate Pair Sequencing of Whole-Genome-Amplified DNA Following Laser Capture Microdissection of Prostate Cancer

High-throughput next-generation sequencing provides a revolutionary platform to unravel the precise DNA aberrations concealed within subgroups of tumour cells. However, in many instances, the limited number of cells makes the application of this technology in tumour heterogeneity studies a challenge. In order to address these limitations, we present a novel methodology to partner laser capture microdissection (LCM) with sequencing platforms, through a whole-genome amplification (WGA) protocol performed in situ directly on LCM engrafted cells. We further adapted current Illumina mate pair (MP) sequencing protocols to the input of WGA DNA and used this technology to investigate large genomic rearrangements in adjacent Gleason Pattern 3 and 4 prostate tumours separately collected by LCM. Sequencing data predicted genome coverage and depths similar to unamplified genomic DNA, with limited repetition and bias predicted in WGA protocols. Mapping algorithms developed in our laboratory predicted high-confidence rearrangements and selected events each demonstrated the predicted fusion junctions upon validation. Rearrangements were additionally confirmed in unamplified tissue and evaluated in adjacent benign-appearing tissues. A detailed understanding of gene fusions that characterize cancer will be critical in the development of biomarkers to predict the clinical outcome. The described methodology provides a mechanism of efficiently defining these events in limited pure populations of tumour tissue, aiding in the derivation of genomic aberrations that initiate cancer and drive cancer progression.

Heterogeneity of Programmed Cell Death Ligand 1 Expression in Multifocal Lung Cancer

Purpose: The expression of programmed cell death ligand 1 (PD-L1) provides limited predictive value in identifying patients most likely to respond to immunotherapy. As the heterogeneity of PD-L1 expression may lead to sampling error and the misclassification of PD-L1 status, we assessed the distribution of PD-L1 expression in paired, resected multifocal lung cancers. Experimental Design: PD-L1 was assessed by IHC. Paired lesions were defined as independent primaries or related lesions using mate pair next-generation sequencing. Agreement statistics were used for analysis. Results: Sixty-seven multifocal lung cancers from 32 patients were sequenced and stained for PD-L1. There was agreement of PD-L1 expression by the tumor cells in paired lesions of 20 patients and disagreement of PD-L1 expression by the tumor cells in paired lesions of 12 patients (κ = 0.01). Sequencing identified that 23 patients had independent primary lung cancers and that 9 patients had related cancers. In paired lesions of patients with independent cancers, there was agreement of PD-L1 expression by the tumor cells in 12 patients and disagreement in 11 patients (κ = 0.31). In paired lesions of patients with related lung cancers, there was agreement of PD-L1 expression by the tumor cells in 8 patients and disagreement in 1 patient (κ = 0.73). Conclusions: The expression of PD-L1 is heterogeneous among paired independent lung cancers, but there are high levels of agreement in intrapulmonary metastasis. Clin Cancer Res; 22(9); 2177–82. ©2015 AACR.

Truncated ERG Oncoproteins from TMPRSS2-ERG Fusions Are Resistant to SPOP-Mediated Proteasome Degradation

SPOP mutations and TMPRSS2-ERG rearrangements occur collectively in up to 65% of human prostate cancers. Although the two events are mutually exclusive, it is unclear whether they are functionally interrelated. Here, we demonstrate that SPOP, functioning as an E3 ubiquitin ligase substrate-binding protein, promotes ubiquitination and proteasome degradation of wild-type ERG by recognizing a degron motif at the N terminus of ERG. Prostate cancer-associated SPOP mutations abrogate the SPOP-mediated degradation function on the ERG oncoprotein. Conversely, the majority of TMPRSS2-ERG fusions encode N-terminal-truncated ERG proteins that are resistant to the SPOP-mediated degradation because of degron impairment. Our findings reveal degradation resistance as a previously uncharacterized mechanism that contributes to elevation of truncated ERG proteins in prostate cancer. They also suggest that overcoming ERG resistance to SPOP-mediated degradation represents a viable strategy for treatment of prostate cancers expressing either mutated SPOP or truncated ERG.

A conditionally replicating adenovirus targeted to tumor cells through activated RAS/P-MAPK-selective mRNA stabilization

The expression of various proteins associated with rapid responses to inflammation and/or proliferation can be controlled at the level of mRNA stability. Because tumor cells continually recapitulate intracellular programs of proliferation, we have used tumor cell–selective stabilization of mRNA as a means to control therapeutic gene expression. We describe an adenoviral vector that is conditionally replication competent in which expression of the essential adenoviral early region 1A (E1A) gene is regulated by ligation to the 3′ untranslated region (UTR) of PTGS2 (also known as COX2), the gene encoding prostaglandin-endoperoxide synthase 2, allowing activated RAS/P-MAPK-specific stabilization of its mRNA. Induction of activated RAS supports replication, whereas matched cells in which activated RAS/P-MAPK is not expressed are very poor substrates for viral replication both in vitro and in vivo. Further tumor-targeting strategies will also be required to prevent viral replication at extratumoral sites where PTGS2 is normally induced. Many different genes contain 3′ UTRs that control selective mRNA stability under different physiological, pathological and tumor-associated conditions. Therefore, generating tumor selectivity at the level of mRNA stability is a strategy with broad potential applicability in vector design.

Lineage Relationship of Gleason Patterns in Gleason Score 7 Prostate Cancer

Gleason score 7 (GS7) prostate cancer [tumors with both Gleason patterns 3 (GP3) and 4 (GP4)] portends a significantly more aggressive tumor than Gleason score 6 (GS6). It is, therefore, critical to understand the molecular relationship of adjacent GP3 and GP4 tumor cell populations and relate molecular abnormalities to disease progression. To decipher molecular relatedness, we used laser capture microdissection (LCM) and whole-genome amplification (WGA) to separately collect and amplify DNA from adjacent GP3 and GP4 cell populations from 14 cases of GS7 prostate cancer. We then carried out massively parallel mate-pair next generation sequencing (NGS) to examine the landscape of large chromosomal alterations. We identified four to 115 DNA breakpoints in GP3 and 17 to 480 in GP4. Our findings indicate that while GP3 and GP4 from the same tumor each possess unique breakpoints, they also share identical ones, indicating a common origin. Approximately 300 chromosomal breakpoints were localized to the regions affected in at least two tumors, whereas more than 3,000 were unique within the set of 14 tumors. TMPRSS2-ERG was the most recurrent rearrangement present in eight cases, in both GP3 and GP4. PTEN rearrangements were found in five of eight TMPRSS2-ERG fusion-positive cases in both GP3 and GP4. Hierarchical clustering analysis revealed that GP3 has greater breakpoint similarity to its partner GP4 compared with GP3 from different patients. We show evidence that LCM, WGA, and NGS of adjacent tumor regions provide an important tool in deciphering lineage relationships and discovering chromosomal alterations associated with tumor progression.

Identification of Independent Primary Tumors and Intrapulmonary Metastases Using DNA Rearrangements in Non–Small-Cell Lung Cancer

PURPOSE Distinguishing independent primary tumors from intrapulmonary metastases in non-small-cell carcinoma remains a clinical dilemma with significant clinical implications. Using next-generation DNA sequencing, we developed a chromosomal rearrangement-based approach to differentiate multiple primary tumors from metastasis. METHODS Tumor specimens from patients with known independent primary tumors and metastatic lesions were used for lineage test development, which was then applied to multifocal tumors. Laser capture microdissection was performed separately for each tumor. Genomic DNA was isolated using direct in situ whole-genome amplification methodology, and next-generation sequencing was performed using an Illumina mate-pair library protocol. Sequence reads were mapped to the human genome, and primers spanning the fusion junctions were used for validation polymerase chain reaction. RESULTS A total of 41 tumor samples were sequenced (33 adenocarcinomas [ADs] and eight squamous cell carcinomas [SQCCs]), with a range of three to 276 breakpoints per tumor identified. Lung tumors predicted to be independent primary tumors based on different histologic subtype did not share any genomic rearrangements. In patients with lung primary tumors and paired distant metastases, shared rearrangements were identified in all tumor pairs, emphasizing the patient specificity of identified breakpoints. Multifocal AD and SQCC samples were reviewed independently by two pulmonary pathologists. Concordance between histology and genomic data occurred in the majority of samples. Discrepant tumor samples were resolved by genome sequencing. CONCLUSION A diagnostic lineage test based on genomic rearrangements from mate-pair sequencing demonstrates promise for distinguishing independent primary from metastatic disease in lung cancer.

Novel integrating adenoviral/retroviral hybrid vector for gene therapy

A hybrid adenoviral vector system was designed to incorporate an excisable retroviral cassette that can be stably integrated into the host cell genome. The vector contains the terminal sequences of two Moloney murine leukemia virus retroviral long terminal repeats (LTRs), fused to form a junction fragment, and is flanked by two loxP recognition sequences. Cre recombinase-directed excision liberates a circular, double-stranded DNA molecule containing the LTR junction fragment. Despite the natural intermediate for retroviral integrase being a linear DNA molecule, we show that, in the presence of Cre and retroviral Gag and Pol, the excised circle can be integrated into the target cell genome through both specific integrase (Int)-directed mechanisms and by a random integration process. The loxP cassette, carrying in addition a selectable marker gene, was incorporated into the E1-deleted region of an adenoviral vector. Infection of cells expressing Cre, Gag, and Pol generated clones that survived long term in drug selection (>3 months). Int-mediated integration was demonstrated in seven of nine clones by sequencing of the integration sites. In addition, the introduction of the loxP cassette into 293 cells coexpressing Cre and Int alone in the absence of other Gag and Pol proteins was sufficient to catalyze the integration mechanism. These experiments demonstrate that it is possible to generate high-titer adenovirus-mediated delivery of a C-type retroviral provirus that can subsequently undergo retroviral Int-mediated integration into dividing and nondividing cells.