A phase 2 study of the sphingosine-1-phosphate antibody sonepcizumab in patients with metastatic renal cell carcinoma.

BACKGROUND: Upregulation of sphingosine-1-phosphate (S1P) may mediate resistance to vascular endothelial growth factor (VEGF)-directed therapies and inhibit antitumor immunity. Antagonism of S1P in preclinical models appears to overcome this resistance. In this phase 2 study, the authors assessed the activity of sonepcizumab, a first-in-class inhibitor of S1P, in patients with metastatic renal cell carcinoma (mRCC) with a history of prior VEGF-directed therapy. METHODS: Patients were required to have clear cell mRCC and to have received treatment with at least 1 prior VEGF-directed agent. Prior treatment with immunotherapeutic agents and ≤1 mammalian target of rapamycin inhibitors was permitted. The primary endpoint of the study was progression-free survival. Additional endpoints included response rate and safety, and overall survival (OS) performed post hoc. RESULTS: A total of 40 patients were enrolled with a median of 3 prior therapies (range, 1-5 prior therapies), 78% of whom had intermediate-risk disease by second-line International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) criteria. Although the current study did not achieve its primary endpoint based on the 2-month progression-free survival, a median OS of 21.7 months was observed. Four patients (10%) demonstrated a partial response, with a median duration of response of 5.9 months. No grade 3/4 treatment-related adverse events were observed in >5% of patients (adverse events were graded and recorded for each patient using Common Terminology Criteria for Adverse Events [version 4.0]); the most frequent grade 1/2 treatment-related adverse events were fatigue (30%), weight gain (18%), constipation (15%), and nausea (15%). Biomarker studies demonstrated an increase in S1P concentrations with therapy. Comprehensive genomic profiling of 3 patients with a clinical benefit of >24 months indicated von Hippel-Lindau (VHL) and polybromo-1 (PBRM1) alterations. CONCLUSIONS: The encouraging OS and favorable safety profile observed with sonepcizumab should prompt further investigation of the agent in combination with VEGF-directed agents or checkpoint inhibitors. Cancer 2017;123:576-582. © 2016 American Cancer Society.

A phase II trial of AS1411 (a novel nucleolin-targeted DNA aptamer) in metastatic renal cell carcinoma.

BACKGROUND: DNA aptamers represent a novel strategy in anti-cancer medicine. AS1411, a DNA aptamer targeting nucleolin (a protein which is overexpressed in many tumor types), was evaluated in patients with metastatic, clear-cell, renal cell carcinoma (RCC) who had failed treatment with ≥1 prior tyrosine kinase inhibitor. METHODS: In this phase II, single-arm study, AS1411 was administered at 40 mg/kg/day by continuous intravenous infusion on days 1-4 of a 28-day cycle, for two cycles. Primary endpoint was overall response rate; progression-free survival (PFS) and safety were secondary endpoints. RESULTS: 35 patients were enrolled and treated. One patient (2.9 %) had a response to treatment. The response was dramatic (84 % reduction in tumor burden by RECIST 1.0 criteria) and durable (patient remains free of progression 2 years after completing therapy). Whole exome sequencing of this patient's tumor revealed missense mutations in the mTOR and FGFR2 genes which is of interest because nucleolin is known to upregulate mTOR pathway activity by enhancing AKT1 mRNA translation. No other responses were seen. Thirty-four percent of patients had an AS1411-related adverse event, all of which were mild or moderate. CONCLUSIONS: AS1411 appears to have minimal activity in unselected patients with metastatic RCC. However, rare, dramatic and durable responses can be observed and toxicity is low. One patient in this study had an excellent response and was found to have FGFR2 and mTOR mutations which will be of interest in future efforts to discover and validate predictive biomarkers of response to nucleolin targeted compounds. DNA aptamers represent a novel way to target cancer cells at a molecular level and continue to be developed with a view to improving treatment and imaging in cancer medicine.

A palindrome-mediated recurrent translocation with 3:1 meiotic nondisjunction: the t(8;22)(q24.13;q11.21).

Palindrome-mediated genomic instability has been associated with chromosomal translocations, including the recurrent t(11;22)(q23;q11). We report a syndrome characterized by extremity anomalies, mild dysmorphia, and intellectual impairment caused by 3:1 meiotic segregation of a previously unrecognized recurrent palindrome-mediated rearrangement, the t(8;22)(q24.13;q11.21). There are at least ten prior reports of this translocation, and nearly identical PATRR8 and PATRR22 breakpoints were validated in several of these published cases. PCR analysis of sperm DNA from healthy males indicates that the t(8;22) arises de novo during gametogenesis in some, but not all, individuals. Furthermore, demonstration that de novo PATRR8-to-PATRR11 translocations occur in sperm suggests that palindrome-mediated translocation is a universal mechanism producing chromosomal rearrangements.

Phase 1 clinical trial of the novel proteasome inhibitor marizomib with the histone deacetylase inhibitor vorinostat in patients with melanoma, pancreatic and lung cancer based on in vitro assessments of the combination.

PURPOSE: Combining proteasome and histone deacetylase (HDAC) inhibition has been seen to provide synergistic anti-tumor activity, with complementary effects on a number of signaling pathways. The novel bi-cyclic structure of marizomib with its unique proteasome inhibition, toxicology and efficacy profiles, suggested utility in combining it with an HDAC inhibitor such as vorinostat. Thus, in this study in vitro studies assessed the potential utility of combining marizomib and vorinostat, followed by a clinical trial with the objectives of assessing the recommended phase 2 dose (RP2D), pharmacokinetics (PK), pharmacodynamics (PD), safety and preliminary anti-tumor activity of the combination in patients. EXPERIMENTAL DESIGN: Combinations of marizomib and vorinostat were assessed in vitro. Subsequently, in a Phase 1 clinical trial patients with melanoma, pancreatic carcinoma or Non-small Cell Lung Cancer (NSCLC) were given escalating doses of weekly marizomib in combination with vorinostat 300 mg daily for 16 days in 28 day cycles. In addition to standard safety studies, proteasome inhibition and pharmacokinetics were assayed. RESULTS: Marked synergy of marizomib and vorinostat was seen in tumor cell lines derived from patients with NSCLC, melanoma and pancreatic carcinoma. In the clinical trial, 22 patients were enrolled. Increased toxicity was not seen with the combination. Co-administration did not appear to affect the PK or PD of either drug in comparison to historical data. Although no responses were demonstrated using RECIST criteria, 61% of evaluable patients demonstrated stable disease with 39% having decreases in tumor measurements. CONCLUSIONS: Treatment of multiple tumor cell lines with marizomib and vorinostat resulted in a highly synergistic antitumor activity. The combination of full dose marizomib with vorinostat is tolerable in patients with safety findings consistent with either drug alone.

Functional analysis of the NUP98-CCDC28A fusion protein.

BACKGROUND: The nucleoporin gene NUP98 is rearranged in more than 27 chromosomal abnormalities observed in childhood and adult, de novo and therapy-related acute leukemias of myeloid and T-lymphoid origins, resulting in the creation of fusion genes and the expression of chimeric proteins. We report here the functional analysis of the NUP98-coiled-coil domain-containing protein 28A (NUP98-CCDC28A) fusion protein, expressed as the consequence of a recurrent t(6;11)(q24.1;p15.5) translocation. DESIGN AND METHODS: To gain insight into the function of the native CCDC28A gene, we collected information on any differential expression of CCDC28A among normal hematologic cell types and within subgroups of acute leukemia. To assess the in vivo effects of the NUP98-CCDC28A fusion, NUP98-CCDC28A or full length CCDC28A were retrovirally transduced into primary murine bone marrow cells and transduced cells were next transplanted into sub-lethally irradiated recipient mice. RESULTS: Our in silico analyses supported a contribution of CCDC28A to discrete stages of murine hematopoietic development. They also suggested selective enrichment of CCDC28A in the French-American-British M6 class of human acute leukemia. Primary murine hematopoietic progenitor cells transduced with NUP98-CCDC28A generated a fully penetrant and transplantable myeloproliferative neoplasm-like myeloid leukemia and induced selective expansion of granulocyte/macrophage progenitors in the bone marrow of transplanted recipients, showing that NUP98-CCDC28A promotes the proliferative capacity and self-renewal potential of myeloid progenitors. In addition, the transformation mediated by NUP98-CCDC28A was not associated with deregulation of the Hoxa-Meis1 pathway, a feature shared by a diverse set of NUP98 fusions. CONCLUSIONS: Our results demonstrate that the recurrent NUP98-CCDC28A is an oncogene that induces a rapid and transplantable myeloid neoplasm in recipient mice. They also provide additional evidence for an alternative leukemogenic mechanism for NUP98 oncogenes.

Up-regulation of homeodomain genes, DLX1 and DLX2, by FLT3 signaling.

BACKGROUND: Activating mutations in fms-like tyrosine kinase-3 (FLT3) are frequent in acute myeloid leukemia and represent both a poor prognostic feature and a therapeutic target. We have identified a previously unrecognized downstream effect of FLT3 activation, namely up-regulation of the homeodomain genes, DLX1 and DLX2. DESIGN AND METHODS: MV4;11 cells with FLT3-internal tandem duplication mutation, RS4;11 cells with wild-type FLT3 and blasts from patients with acute myeloid leukemia were used to pursue the relation between FLT3, DLX1/2 and transforming growth factor-ß (TGFß). Real-time quantitative reverse transcriptase polymerase chain reaction, western blot and reverse-phase protein array were performed to detect changes in gene and protein expression. RNA interference and MTS assays were used to study the interaction of PKC412, FLT3 inhibitor and TGFß1. RESULTS: A direct relationship between FLT3 activity and DLX1/2 expression was revealed by both inhibition and up-regulation of FLT3 signaling in MV4;11 and RS4;11 cell lines, respectively, in isolated blast cells from patients with acute myeloid leukemia, and in reverse-phase protein array assays of samples from patients with acute myeloid leukemia. Mechanistically, the link between FLT3 and DLX1 expression appears to involve MAPK signaling through the ERK and JNK pathways. To determine whether elevated DLX1 had a functional consequence, we explored the reported inhibition by DLX1 on TGFß/Smad signaling. Indeed, TGFß responses were blunted by FLT3 activation in a DLX1-dependent manner and FLT3 inhibition resulted in a time-dependent increase in nuclear phospho-Smad2. CONCLUSIONS: These findings suggest that alterations in DLX1/2 contribute to the biological consequences of FLT3 activation.

Neuropilin-2b facilitates resistance to tyrosine kinase inhibitors in non-small cell lung cancer.

OBJECTIVE: Innate and acquired resistance is the principle factor limiting the efficacy of tyrosine kinase inhibitors in lung cancer. We have observed a dramatic upregulation of the cell surface co-receptor neuropilin-2b in lung cancers clinically treated with tyrosine kinase inhibitors correlating with acquired resistance. We hypothesize that neuropilin-2b plays a functional role in acquired tyrosine kinase inhibitor resistance. METHODS: Non-small cell lung cancer proliferation and survival were determined during chronic tyrosine kinase inhibitor exposure in the presence or absence of neuropilin-2b knock-down. Interactions of neuropilin-2a and neuropilin-2b isoforms with PTEN and GSK3ß were assessed by immunoprecipitation. Neuropilin-2a and neuropilin-2b mutants deleted for their cytoplasmic domains were used to identify regions responsible for neuropilin-2b-GSK3ß interaction. Because GSK3ß is known to phosphorylate and degrade PTEN, phospho-PTEN and total PTEN levels were assessed after transfection of neuropilin-2a and neuropilin-2b wild-type and mutant constructs. RESULTS: Non-small cell lung cancer cells chronically treated with gefitinib or osimertinib developed drug resistance and exhibited logarithmic growth in the presence of endothelial growth factor receptor tyrosine kinase inhibitors. However, neuropilin-2b knockdown cells remained sensitive to gefitinib. Likewise, neuropilin-2b knockdown suppressed and neuropilin-2a knockdown enhanced cellular migration. Acquired drug resistance and cell migration correlated with neuropilin-2b-dependent AKT activation with the intermediate step of GSK3ß-dependent PTEN degradation. A specific binding site for GSK3ß on the cytoplasmic domain of neuropilin-2b was identified with truncated protein constructs and computer modeling. CONCLUSIONS: Neuropilin-2b facilitates non-small cell lung cancer resistance to tyrosine kinase inhibitors, and this biological effect relates to AKT activation. Neuropilin-2b GSK3ß interactions appear to be essential for PTEN degradation and AKT activation in lung cancer cells. Disruption of the neuropilin-2b GSK3ß interaction may represent a novel treatment strategy to preserve sensitivity to tyrosine kinase inhibitors in non-small cell lung cancer.

Safety and efficacy of sorafenib in elderly patients treated in the North American advanced renal cell carcinoma sorafenib expanded access program.

OBJECTIVE: In this retrospective analysis of the Advanced Renal Cell Carcinoma Sorafenib (ARCCS) program in North America, we compared the safety and efficacy of sorafenib in patients aged ≥70 with those aged <70 years. METHODS: Patients were treated with oral sorafenib twice daily until the occurrence of disease progression or treatment intolerance. The primary objective of the ARCCS program was making sorafenib available to patients with advanced renal cell carcinoma (RCC) in the USA and Canada before marketing approval was obtained; the secondary objective was the evaluation of its safety and efficacy. RESULTS: Of the 2,504 patients enrolled in the ARCCS program who received at least 1 dose of sorafenib, 736 (29%) were aged ≥70 years. The most common grade ≥3 adverse events included rash/desquamation (5% in both groups), hand-foot skin reaction (8% in those aged ≥70 years vs. 10% in those <70 years of age), hypertension (5 vs. 4%) and fatigue (7 vs. 4%). Partial response was seen in 4% of the patients in both age groups. The median overall survival for the ≥70-year versus <70-year groups was also similar (46 vs. 50 weeks). CONCLUSIONS: There were no substantial differences in safety and efficacy between patients aged ≥70 and <70 years with advanced RCC treated with sorafenib.

HOX gene expression in phenotypic and genotypic subgroups and low HOXA gene expression as an adverse prognostic factor in pediatric ALL.

BACKGROUND: HOX genes play an important role in both normal lymphopoiesis and leukemogenesis. However, HOX expression patterns in leukemia cells compared to normal lymphoid progenitors have not been systematically studied in acute lymphoblastic leukemia (ALL) subtypes. PROCEDURE: The RNA expression levels of HOXA, HOXB, and CDX1/2 genes were analyzed by qRT-PCR in a cohort of 61 diagnostic pediatric ALL samples and FACS-sorted subpopulations of normal lymphoid progenitors. RESULTS: The RNA expression of HOXA7-10, HOXA13, and HOXB2-4 genes was exclusively detected in leukemic cells and immature progenitors. The RNA expression of HOXB6 and CDX2 genes was exclusively detected in leukemic cells but not in B-lineage cells at any of the studied developmental stages. HOXA3-4, HOXA7, and HOXB3-4 genes were differentially expressed between BCP-ALL and T-ALL subgroups, and among genotypically defined MLL/AF4, TEL/AML1, BCR/ABL, hyperdiploid and normal karyotype subgroups. However, this differential expression did not define specific clusters in hierarchical cluster analysis. HOXA7 gene was low expressed at the RNA level in patients with hyperdiploid leukemia, whereas HOXB7 and CDX2 genes were low expressed in TEL/AML1-positive and BCR/ABL-positive cases, respectively. In contrast to previous findings in acute myeloid leukemia, high HOXA RNA expression was associated with an excellent prognosis in Cox's regression model (P = 0.03). In MLL/AF4-positive ALL, lower HOXA RNA expression correlated with the methylation status of their promoters. CONCLUSIONS: HOX gene RNA expression cannot discriminate leukemia subgroups or relative maturity of leukemic cells. However, HOXA RNA expression correlates with prognosis, and particular HOX genes are expressed in specific genotypically characterized subgroups.

The tumor suppressor gene TRC8/RNF139 is disrupted by a constitutional balanced translocation t(8;22)(q24.13;q11.21) in a young girl with dysgerminoma.

BACKGROUND: RNF139/TRC8 is a potential tumor suppressor gene with similarity to PTCH, a tumor suppressor implicated in basal cell carcinomas and glioblastomas. TRC8 has the potential to act in a novel regulatory relationship linking the cholesterol/lipid biosynthetic pathway with cellular growth control and has been identified in families with hereditary renal (RCC) and thyroid cancers. Haploinsufficiency of TRC8 may facilitate development of clear cell-RCC in association with VHL mutations, and may increase risk for other tumor types. We report a paternally inherited balanced translocation t(8;22) in a proposita with dysgerminoma. METHODS: The translocation was characterized by FISH and the breakpoints cloned, sequenced, and compared. DNA isolated from normal and tumor cells was checked for abnormalities by array-CGH. Expression of genes TRC8 and TSN was tested both on dysgerminoma and in the proposita and her father. RESULTS: The breakpoints of the translocation are located within the LCR-B low copy repeat on chromosome 22q11.21, containing the palindromic AT-rich repeat (PATRR) involved in recurrent and non-recurrent translocations, and in an AT-rich sequence inside intron 1 of the TRC8 tumor-suppressor gene at 8q24.13. TRC8 was strongly underexpressed in the dysgerminoma. Translin is underexpressed in the dysgerminoma compared to normal ovary.TRC8 is a target of Translin (TSN), a posttranscriptional regulator of genes transcribed by the transcription factor CREM-tau in postmeiotic male germ cells. CONCLUSION: A role for TRC8 in dysgerminoma may relate to its interaction with Translin. We propose a model in which one copy of TRC8 is disrupted by a palindrome-mediated translocation followed by complete loss of expression through suppression, possibly mediated by miRNA.

Semaphorin SEMA3F affects multiple signaling pathways in lung cancer cells.

Loss of SEMA3F occurs frequently in lung cancer and correlates with advanced stage of disease. We previously reported that SEMA3F blocked tumor formation by H157 lung cancer cells in a rat orthotopic model. This was associated with loss of activated alpha(V)beta(3) integrin, impaired cell adhesion to extracellular matrix components, and down-regulation of phospho-extracellular signal-regulated kinase 1/2 (ERK1/2). These results suggested that SEMA3F might interfere with integrin outside-in signaling. In the present report, we found that SEMA3F decreased adhesion to vitronectin, whereas integrin-linked kinase (ILK) kinase activity was down-regulated in SEMA3F-expressing H157 cells. Exposure to SEMA3F-conditioned medium led to diminution of phospho-ERK1/2 in four of eight lung cancer cell lines, and ILK silencing by small interfering RNA led to similar loss of phospho-ERK1/2 in H157 cells. Moreover, SEMA3F expression (with constitutive and inducible systems) also reduced AKT and signal transducer and activator of transcription 3 (STAT3) phosphorylation independently of ILK-ERK1/2. These signaling changes extended downstream to hypoxia-inducible factor-1alpha (HIF-1alpha) protein and vascular endothelial growth factor (VEGF) mRNA levels, which were both reduced in three of four SEMA3F-transfected cell lines. Mechanistically, the effects on HIF-1alpha were consistent with inhibition of its AKT-driven protein translation initiation, with no effect on HIF-1alpha mRNA level or protein degradation. Furthermore, when H157 cells were injected s.c. in nude mice, tumors derived from SEMA3F-expressing cells showed lower microvessel density and tumor growth. These results show that SEMA3F negatively affects ILK-ERK1/2 and AKT-STAT3 signaling, along with inhibition of HIF-1alpha and VEGF. These changes would be anticipated to contribute significantly to the observed antitumor activity of SEMA3F.

Cyclooxygenase-2-dependent regulation of E-cadherin: prostaglandin E(2) induces transcriptional repressors ZEB1 and snail in non-small cell lung cancer.

Elevated tumor cyclooxygenase-2 (COX-2) expression is associated with tumor invasion, metastasis, and poor prognosis in non-small cell lung cancer (NSCLC). Here, we report that COX-2-dependent pathways contribute to the modulation of E-cadherin expression in NSCLC. First, whereas genetically modified COX-2-sense (COX-2-S) NSCLC cells expressed low E-cadherin and showed diminished capacity for cellular aggregation, genetic or pharmacologic inhibition of tumor COX-2 led to increased E-cadherin expression and resulted in augmented homotypic cellular aggregation among NSCLC cells in vitro. An inverse relationship between COX-2 and E-cadherin was shown in situ by double immunohistochemical staining of human lung adenocarcinoma tissue sections. Second, treatment of NSCLC cells with exogenous prostaglandin E(2) (PGE(2)) significantly decreased the expression of E-cadherin, whereas treatment of COX-2-S cells with celecoxib (1 mumol/L) led to increased E-cadherin expression. Third, the transcriptional suppressors of E-cadherin, ZEB1 and Snail, were up-regulated in COX-2-S cells or PGE(2)-treated NSCLC cells but decreased in COX-2-antisense cells. PGE(2) exposure led to enhanced ZEB1 and Snail binding at the chromatin level as determined by chromatin immunoprecipitation assays. Small interfering RNA-mediated knockdown of ZEB1 or Snail interrupted the capacity of PGE(2) to down-regulate E-cadherin. Fourth, an inverse relationship between E-cadherin and ZEB1 and a direct relationship between COX-2 and ZEB1 were shown by immunohistochemical staining of human lung adenocarcinoma tissue sections. These findings indicate that PGE(2), in autocrine or paracrine fashion, modulates transcriptional repressors of E-cadherin and thereby regulates COX-2-dependent E-cadherin expression in NSCLC. Thus, blocking PGE(2) production or activity may contribute to both prevention and treatment of NSCLC.

Restoring E-cadherin expression increases sensitivity to epidermal growth factor receptor inhibitors in lung cancer cell lines.

The epidermal growth factor receptor (EGFR) is overexpressed in the majority of non-small cell lung cancers (NSCLC). EGFR tyrosine kinase inhibitors, such as gefitinib and erlotinib, produce 9% to 27% response rates in NSCLC patients. E-Cadherin, a calcium-dependent adhesion molecule, plays an important role in NSCLC prognosis and progression, and interacts with EGFR. The zinc finger transcriptional repressor, ZEB1, inhibits E-cadherin expression by recruiting histone deacetylases (HDAC). We identified a significant correlation between sensitivity to gefitinib and expression of E-cadherin, and ZEB1, suggesting their predictive value for responsiveness to EGFR-tyrosine kinase inhibitors. E-Cadherin transfection into a gefitinib-resistant line increased its sensitivity to gefitinib. Pretreating resistant cell lines with the HDAC inhibitor, MS-275, induced E-cadherin along with EGFR and led to a growth-inhibitory and apoptotic effect of gefitinib similar to that in gefitinib-sensitive NSCLC cell lines including those harboring EGFR mutations. Thus, combined HDAC inhibitor and gefitinib treatment represents a novel pharmacologic strategy for overcoming resistance to EGFR inhibitors in patients with lung cancer.

Epigenetic Regulation of the Epithelial to Mesenchymal Transition in Lung Cancer.

Lung cancer is the leading cause of cancer deaths worldwide. It is an aggressive and devastating cancer because of metastasis triggered by enhanced migration and invasion, and resistance to cytotoxic chemotherapy. The epithelial to mesenchymal transition (EMT) is a fundamental developmental process that is reactivated in wound healing and a variety of diseases including cancer where it promotes migration/invasion and metastasis, resistance to treatment, and generation and maintenance of cancer stem cells. The induction of EMT is associated with reprogramming of the epigenome. This review focuses on major mechanisms of epigenetic regulation mainly in lung cancer with recent data on EZH2 (enhancer of zeste 2 polycomb repressive complex 2 subunit ), the catalytic subunit of the PRC2 (Polycomb Group PcG), that behaves as an oncogene in lung cancer associated with gene repression, non-coding RNAs and the epitranscriptome.

The neuropilin 2 isoform NRP2b uniquely supports TGFß-mediated progression in lung cancer.

Neuropilins (NRP1 and NRP2) are co-receptors for heparin-binding growth factors and class 3 semaphorins. Different isoforms of NRP1 and NRP2 are produced by alternative splicing. We found that in non-small cell lung cancer (NSCLC) cell lines, transforming growth factor-ß (TGFß) signaling preferentially increased the abundance of NRP2b. NRP2b and NRP2a differ only in their carboxyl-terminal regions. Although the presence of NRP2b inhibited cultured cell proliferation and primary tumor growth, NRP2b enhanced cellular migration, invasion into Matrigel, and tumorsphere formation in cultured cells in response to TGFß signaling and promoted metastasis in xenograft mouse models. These effects of overexpressed NRP2b contrast with the effects of overexpressed NRP2a. Hepatocyte growth factor (HGF)-induced phosphorylation of the kinase AKT was specifically promoted by NRP2b, whereas inhibiting the HGF receptor MET attenuated NRP2b-dependent cell migration. Unlike NRP2a, NRP2b did not bind the PDZ domain scaffolding protein GAIP carboxyl terminus-interacting protein (GIPC1) and only weakly recruited phosphatase and tensin homolog (PTEN), potentially explaining the difference between NRP2b-mediated and NRP2a-mediated effects. Analysis of NSCLC patient tumors showed that NRP2b abundance correlated with that of the immune cell checkpoint receptor ligand PD-L1 as well as with epithelial-to-mesenchymal transition (EMT) phenotypes in the tumors, acquired resistance to epidermal growth factor receptor (EGFR) inhibitors, disease progression, and poor survival in patients. NRP2b knockdown attenuated the acquisition of resistance to the EGFR inhibitor gefitinib in cultured NSCLC cells. Thus, in NSCLC, NRP2b contributed to the oncogenic response to TGFß and correlated with tumor progression in patients.

Growth suppression induced by the TRC8 hereditary kidney cancer gene is dependent upon JAB1/CSN5.

TRC8 encodes an E3-ubiquitin ligase disrupted in a family with hereditary renal cell carcinoma (RCC). We previously reported that Drosophila Trc8 (DTrc8) overexpression inhibits growth and that human and fly proteins interact with with the COP9 signalosome (CSN) subunit JAB1/CSN5. However, further mechanistic evidence linking DTrc8 growth suppression to CSN5 was lacking. Here, we show that haploinsufficiency of CSN5, or a T100I point mutation (CSN5(3)), relieved growth suppression by DTrc8, whereas CSN5(1) (E160V) and CSN5(2) (G147D) mutations had no effect. The strength of yeast two-hybrid interactions between DTrc8 and CSN5 were in complete agreement with the observed phenotypes. DTrc8 overexpression resulted in elevated levels of CSN5 and CSN7, but had no effect on NEDD8-modified Cul-1. In contrast to CSN5, heterozygosity for CSN4null had no effect on the DTrc8 phenotype. We also looked for genetic interactions between DTrc8 and other MPN domain proteins in the CSN and 26S proteasome lid. CSN6 haploinsufficiency restored growth, whereas reduction of proteasome subunits RPN8 or RPN11 had no effect. DTrc8 expression increased the level of digitonin-extractable CSN complex, consistent with elevated levels of CSN5 and 7. Our genetic results confirm that DTrc8-induced growth suppression is CSN5 (and CSN6) dependent. While there was no obvious influence on CSN deneddylation activity, the increase in CSN subunits and holocomplex suggests that TRC8 modulates signalosome levels or compartmentalization.

Promoter characterization of Semaphorin SEMA3F, a tumor suppressor gene.

The tumor suppressor gene, Semaphorin SEMA3F, is frequently downregulated in lung cancer. Understanding the specific mechanism of SEMA3F suppression should be informative in terms of epithelial carcinogenesis and potential therapeutic interventions. Although a CpG-island is located 5083-3927 nt upstream of the translation start site, there have been no previous reports dealing with SEMA3F promoter regulation. We have now mapped the transcriptional initiation sites within the CpG-island and defined the region necessary for transcriptional activation. We then looked for evidence of SEMA3F promoter methylation since SEMA3F mutations are rare. By Southern blot and methylation-specific PCR assays, we identified a region in cell lines (i.e., area d at position minus 3850-3644 nt) for which methylation was significantly (P<0.0001) correlated with loss of expression. However, histone deacetylase inhibition with Trichostatin A was much more effective than 5-aza-2'-deoxycytidine in stimulating SEMA3F. Our results suggest that while SEMA3F promoter methylation correlates with repression, chromatin remodeling through histone deacetylase inhibition is sufficient to activate SEMA3F expression.

Urothelial carcinoma of donor origin in a kidney transplant patient.

BACKGROUND: Malignancy after transplantation is an uncommon multifactorial occurrence. Immunosuppression to prevent graft rejection is described as a major risk factor in malignancy development in the post-transplant state. Donor-derived malignancy is a rare reported complication. Herein, we review our patient history and discuss diagnostic strategies and the implications of immunosuppression for donor-derived malignancy. CASE PRESENTATION: This is a 69-year-old man with post-renal-transplant urothelial carcinoma determined to be of donor origin. His course was complicated by BK virus at six years post-transplant; urothelial carcinoma was identified nine years post-transplant. Cystectomy was performed, but because of immunosuppression and underlying chronic kidney disease, the patient was considered ineligible for adjuvant chemotherapy. Two years after resection, screening MRI demonstrated retroperitoneal lymphadenopathy and a right upper pole mass in the transplanted kidney. Urine cytology confirmed the presence of malignant cells; FISH showed 2-8 copies of the X chromosome and no Y chromosome consistent with female origin of the malignant cells. CT-guided renal mass and paraaortic lymph node biopsies demonstrated that about 50 % of cells had an XY complement, while the remainder showed a XX genotype by chromosomal SNP microarray analysis. Immunosuppression was discontinued and the donor kidney removed. X/Y FISH of the urothelial carcinoma identified in the explanted kidney confirmed that the malignant cells were of female donor origin. Follow-up at 3, 6 and 12 months after discontinuation of immunosuppression and surgery demonstrated normalization of the lymphadenopathy and absence of new lesions. CONCLUSIONS: Immunosuppression is a major risk factor for development of malignancy in transplant recipients. Donor-derived malignancy can arise and current molecular studies allow an accurate diagnosis. Withdrawal of immunosuppression and surgical resection of the transplant kidney proved an effective treatment in our case.

ZEB1 Mediates Acquired Resistance to the Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitors in Non-Small Cell Lung Cancer.

Epithelial-mesenchymal transition (EMT) is one mechanism of acquired resistance to inhibitors of the epidermal growth factor receptor-tyrosine kinases (EGFR-TKIs) in non-small cell lung cancer (NSCLC). The precise mechanisms of EMT-related acquired resistance to EGFR-TKIs in NSCLC remain unclear. We generated erlotinib-resistant HCC4006 cells (HCC4006ER) by chronic exposure of EGFR-mutant HCC4006 cells to increasing concentrations of erlotinib. HCC4006ER cells acquired an EMT phenotype and activation of the TGF-ß/SMAD pathway, while lacking both T790M secondary EGFR mutation and MET gene amplification. We employed gene expression microarrays in HCC4006 and HCC4006ER cells to better understand the mechanism of acquired EGFR-TKI resistance with EMT. At the mRNA level, ZEB1 (TCF8), a known regulator of EMT, was >20-fold higher in HCC4006ER cells than in HCC4006 cells, and increased ZEB1 protein level was also detected. Furthermore, numerous ZEB1 responsive genes, such as CDH1 (E-cadherin), ST14, and vimentin, were coordinately regulated along with increased ZEB1 in HCC4006ER cells. We also identified ZEB1 overexpression and an EMT phenotype in several NSCLC cells and human NSCLC samples with acquired EGFR-TKI resistance. Short-interfering RNA against ZEB1 reversed the EMT phenotype and, importantly, restored erlotinib sensitivity in HCC4006ER cells. The level of micro-RNA-200c, which can negatively regulate ZEB1, was significantly reduced in HCC4006ER cells. Our results suggest that increased ZEB1 can drive EMT-related acquired resistance to EGFR-TKIs in NSCLC. Attempts should be made to explore targeting ZEB1 to resensitize TKI-resistant tumors.

The TRC8 hereditary kidney cancer gene suppresses growth and functions with VHL in a common pathway.

VHL is part of an SCF related E3-ubiquitin ligase complex with 'gatekeeper' function in renal carcinoma. However, no mutations have been identified in VHL interacting proteins in wild type VHL tumors. We previously reported that the TRC8 gene was interrupted by a t(3;8) translocation in a family with hereditary renal and non-medullary thyroid cancer. TRC8 encodes a multi-membrane spanning protein containing a RING-H2 finger with in vitro ubiquitin ligase activity. We isolated the Drosophila homologue, DTrc8, and studied its function by genetic manipulations and a yeast 2-hybrid screen. Human and Drosophila TRC8 proteins localize to the endoplasmic reticulum. Loss of either DTrc8 or DVhl resulted in an identical ventral midline defect. Direct interaction between DTrc8 and DVhl was confirmed by GST-pulldown and co-immunoprecipitation experiments. CSN-5/JAB1 is a component of the COP9 signalosome, recently shown to regulate SCF function. We found that DTrc8 physically interacts with CSN-5 and that human JAB1 localization is dependent on VHL mutant status. Lastly, overexpression of DTrc8 inhibited growth consistent with its presumed role as a tumor suppressor gene. Thus, VHL, TRC8, and JAB1 appear to be linked both physically and functionally and all three may participate in the development of kidney cancer.