Designing a HER2/neu promoter to drive α1,3galactosyltransferase expression for targeted anti-αGal antibody-mediated tumor cell killing

INTRODUCTION: Our goal was to specifically render tumor cells susceptible to natural cytolytic anti-αGal antibodies by using a murine α1,3galactosyltransferase (mαGalT) transgene driven by a designed form of HER2/neu promoter (pNeu), the transcription of which is frequently observed to be above basal in breast tumors. Indeed, the αGalT activity that promotes Galα1,3Galβ1,4GlcNAc-R (αGal) epitope expression has been mutationally disrupted during the course of evolution, starting from Old World primates, and this has led to the counter-production of large amounts of cytotoxic anti-αGal antibodies in recent primates, including man. METHOD: Expression of the endogenous c-erbB-2 gene was investigated in various cell lines by northern blotting. A mαGalT cDNA was constructed into pcDNA3 vector downstream of the original CMV promoter (pCMV/mαGalT) and various forms of pNeu were prepared by PCR amplification and inserted in the pCMV/mαGalT construct upstream of the mαGalT cDNA, in the place of the CMV promoter. These constructs were transferred into HEK-293 control and breast tumor cell lines. Stably transfected cells were analyzed by northern blotting for their expression of αGalT and c-erbB-2, and by flow cytometry for their binding with fluorescein isothiocyanate-conjugated Griffonia simplicifolia/isolectin B4. RESULTS: We show that expression of the mαGalT was up- or down-modulated according to the level of endogenous pNeu activity and the particular form of constructed pNeu. Among several constructs, two particular forms of the promoter, pNeu250 containing the CCAAT box and the PEA3 motif adjacent to the TATAA box, and pNeu664, which has three additional PEA3 motifs upstream of the CCAAT box, were found to promote differential αGalT expression. CONCLUSION: Our results strengthen current concepts about the crucial role played by the proximal PEA3 motif of pNeu, and may represent a novel therapeutic approach for the development of targeted transgene expression

EGFR and EGFRvIII Expression in Primary Breast Cancer and Cell Lines

EGFRvIII is a constitutively activated truncated variant of the epidermal growth factor receptor (EGFR) which has been shown to increase tumorgenicity. There are conflicting reports on the extent of EGFRvIII expression in tissues which may in part stem from the use of different assay methodologies. We investigated the expression of both EGFRvIII and wild-type EGFR (EGFRwt) in cell lines and primary breast cancers. First, we used a RT-PCR assay that can simultaneously measure EGFRwt and EGFRvIII mRNA to screen 55 tumor cell lines. We show that except for EGFRvIII transfected cells, only EGFRwt was detected. We then validated a real-time PCR assay and used this to screen 170 formalin fixed paraffin-embedded primary breast cancers for evidence of EGFRwt and EGFRvIII expression. No samples were positive for EGFRvIII expression except for control transfectants and glioblastomas. In contrast, EGFRwt was expressed at varying levels in the majority of samples tested. We conclude that the expression of EGFRvIII is extremely rare in breast cancer and therefore it does not contribute to the malignant phenotype.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44224/1/10549_2004_Article_5274918.pd

Engineering and characterisation of chimeric monoclonal antibody 806 (ch806) for targeted immunotherapy of tumours expressing de2-7 EGFR or amplified EGFR

We report the generation of a chimeric monoclonal antibody (ch806) with specificity for an epitope on the epidermal growth factor receptor (EGFR) that is different from that targeted by all other anti-EGFR therapies. Ch806 antibody is reactive to both de2-7 and overexpressed wild-type (wt) EGFR but not native EGFR expressed in normal tissues at physiological levels. Ch806 was stably expressed in CHO (DHFR −/−) cells and purified for subsequent characterisation and validated for use in preliminary immunotherapy investigations. Ch806 retained the antigen binding specificity and affinity of the murine parental antibody. Furthermore, ch806 displayed enhanced antibody-dependent cellular cytotoxicity against target cells expressing the 806 antigen in the presence of human effector cells. Ch806 was successfully radiolabelled with both iodine-125 and indium-111 without loss of antigen binding affinity or specificity. The radioimmunoconjugates were stable in the presence of human serum at 37°C for up to 9 days and displayed a terminal half-life (T1/2β) of approximately 78 h in nude mice. Biodistribution studies undertaken in BALB/c nude mice bearing de2-7 EGFR-expressing or amplified EGFR-expressing xenografts revealed that 125I-labelled ch806 failed to display any significant tumour retention. However, specific and prolonged tumour localisation of' 111In-labelled ch806 was demonstrated with uptake of 31%ID g−1 and a tumour to blood ratio of 5 : 1 observed at 7 days postinjection. In vivo therapy studies with ch806 demonstrated significant antitumour effects on established de2-7 EGFR xenografts in BALB/c nude mice compared to control, and both murine 806 and the anti-EGFR 528 antibodies. These results support a potential therapeutic role of ch806 in the treatment of suitable EGFR-expressing tumours, and warrants further investigation of the potential of ch806 as a therapeutic agent

Phosphorylation of Nicastrin by SGK1 Leads to Its Degradation through Lysosomal and Proteasomal Pathways

The gamma-secretase complex is involved in the intramembranous proteolysis of a variety of substrates, including the amyloid precursor protein and the Notch receptor. Nicastrin (NCT) is an essential component of the gamma-secretase complex and functions as a receptor for gamma-secretase substrates. In this study, we determined that serum- and glucocorticoid-induced protein kinase 1 (SGK1) markedly reduced the protein stability of NCT. The SGK1 kinase activity was decisive for NCT degradation and endogenous SGK1 inhibited gamma-secretase activity. SGK1 downregulates NCT protein levels via proteasomal and lysosomal pathways. Furthermore, SGK1 directly bound to and phosphorylated NCT on Ser437, thereby promoting protein degradation. Collectively, our findings indicate that SGK1 is a gamma-secretase regulator presumably effective through phosphorylation and degradation of NCT

Immunohistochemical discrimination of wild-type EGFR from EGFRvIII in fixed tumour specimens using anti-EGFR mAbs ICR9 and ICR10

Background:The human epidermal growth factor receptor (EGFR) is an important therapeutic target in oncology, and three different types of EGFR inhibitors have been approved for the treatment of cancer patients. However, there has been no clear association between the expression levels of EGFR protein in the tumours determined by the FDA-approved EGFR PharmDx kit (Dako) or other standard anti-EGFR antibodies and the response to the EGFR inhibitors.Method:In this study, we investigated the potential of our anti-EGFR monoclonal antibodies (mAbs; ICR9, ICR10, ICR16) for immunohistochemical diagnosis of wild-type EGFR and/or the type-III deletion mutant form of EGFR (EGFRvIII) in formalin-fixed, paraffin-embedded human tumour specimens.Results:We found that the anti-EGFR mAb in the EGFR PharmDx kit stained both wild-type and EGFRvIII-expressing cells in formalin-fixed, paraffin-embedded sections. This pattern of EGFR immunostaining was also found with our anti-EGFR mAb ICR16. In contrast, mAbs ICR10 and ICR9 were specific for the wild-type EGFR.Conclusion:We conclude that mAbs ICR9 and ICR10 are ideal tools for investigating the expression patterns of wild-type EGFR protein in tumour specimens using immunohistochemistry, and to determine their prognostic significance, as well as predictive value for response to therapy with EGFR antibodies.British Journal of Cancer advance online publication, 7 February 2012; doi:10.1038/bjc.2012.27 www.bjcancer.com

MUC1 alters oncogenic events and transcription in human breast cancer cells

INTRODUCTION: MUC1 is an oncoprotein whose overexpression correlates with aggressiveness of tumors and poor survival of cancer patients. Many of the oncogenic effects of MUC1 are believed to occur through interaction of its cytoplasmic tail with signaling molecules. As expected for a protein with oncogenic functions, MUC1 is linked to regulation of proliferation, apoptosis, invasion, and transcription. METHODS: To clarify the role of MUC1 in cancer, we transfected two breast cancer cell lines (MDA-MB-468 and BT-20) with small interfering (si)RNA directed against MUC1 and analyzed transcriptional responses and oncogenic events (proliferation, apoptosis and invasion). RESULTS: Transcription of several genes was altered after transfection of MUC1 siRNA, including decreased MAP2K1 (MEK1), JUN, PDGFA, CDC25A, VEGF and ITGAV (integrin α(v)), and increased TNF, RAF1, and MMP2. Additional changes were seen at the protein level, such as increased expression of c-Myc, heightened phosphorylation of AKT, and decreased activation of MEK1/2 and ERK1/2. These were correlated with cellular events, as MUC1 siRNA in the MDA-MB-468 line decreased proliferation and invasion, and increased stress-induced apoptosis. Intriguingly, BT-20 cells displayed similar levels of apoptosis regardless of siRNA, and actually increased proliferation after MUC1 siRNA. CONCLUSION: These results further the growing knowledge of the role of MUC1 in transcription, and suggest that the regulation of MUC1 in breast cancer may be more complex than previously appreciated. The differences between these two cell lines emphasize the importance of understanding the context of cell-specific signaling events when analyzing the oncogenic functions of MUC1, and caution against generalizing the results of individual cell lines without adequate confirmation in intact biological systems

Promoter methylation of RASSF1A and DAPK and mutations of K-ras, p53, and EGFR in lung tumors from smokers and never-smokers

<p>Abstract</p> <p>Background</p> <p>Epidemiological studies indicate that some characteristics of lung cancer among never-smokers significantly differ from those of smokers. Aberrant promoter methylation and mutations in some oncogenes and tumor suppressor genes are frequent in lung tumors from smokers but rare in those from never-smokers. In this study, we analyzed promoter methylation in the <it>ras-association domain isoform A (RASSF1A) </it>and the <it>death-associated protein kinase (DAPK) </it>genes in lung tumors from patients with primarily non-small cell lung cancer (NSCLC) from the Western Pennsylvania region. We compare the results with the smoking status of the patients and the mutation status of the K-<it>ras</it>, <it>p53</it>, and <it>EGFR </it>genes determined previously on these same lung tumors.</p> <p>Methods</p> <p>Promoter methylation of the <it>RASSF1A </it>and <it>DAPK </it>genes was analyzed by using a modified two-stage methylation-specific PCR. Data on mutations of K-<it>ras</it>, <it>p53</it>, and <it>EGFR </it>were obtained from our previous studies.</p> <p>Results</p> <p>The <it>RASSF1A </it>gene promoter methylation was found in tumors from 46.7% (57/122) of the patients and was not significantly different between smokers and never-smokers, but was associated significantly in multiple variable analysis with tumor histology (p = 0.031) and marginally with tumor stage (p = 0.063). The <it>DAPK </it>gene promoter methylation frequency in these tumors was 32.8% (40/122) and did not differ according to the patients' smoking status, tumor histology, or tumor stage. Multivariate analysis adjusted for age, gender, smoking status, tumor histology and stage showed that the frequency of promoter methylation of the <it>RASSF1A </it>or <it>DAPK </it>genes did not correlate with the frequency of mutations of the K<it>-ras, p53</it>, and <it>EGFR </it>gene.</p> <p>Conclusion</p> <p>Our results showed that <it>RASSF1A </it>and <it>DAPK </it>genes' promoter methylation occurred frequently in lung tumors, although the prevalence of this alteration in these genes was not associated with the smoking status of the patients or the occurrence of mutations in the K-<it>ras</it>, <it>p53 </it>and <it>EGFR </it>genes, suggesting each of these events may represent independent event in non-small lung tumorigenesis.</p

Alterations in the insulin-like growth factor system during treatment with diethylstilboestrol in patients with metastatic breast cancer

Alterations in the insulin-like growth factor (IGF)-system were evaluated in 16 patients treated with diethylstilboestrol 5 mg 3 times daily. Fasting blood samples were obtained before treatment and after 2 weeks, 1 month and/or 2–3 months on therapy. Insulin-like growth factor (IGF)-I, IGF-II, free IGF-I, IGF-binding protein (IGFBP)-1, IGFBP-2 and IGFBP-3 were measured by radioimmuno-/immunoradiometric-assays. All samples were subjected to Western ligand blotting as well as immunoblotting for IGFBP-3. We observed a significant decrease (percentage of pretreatment levels with 95 confidence intervals of the mean) in IGF-I [2 weeks 63% (49–79); 1 month 56% (44–73); 2–3 months 66% (53–82)], IGF-II [2 weeks 67% (56–80); 1 month 60% (52–68); 2–3 months 64% (55–75)], free IGF-I [2 weeks 29% (19–42); 1 month 25% (18–36); 2–3 months 31% (21–46)], IGFBP-2 [2 weeks 53% (18–156); 1 month 69% (61–78); 2–3 months 66% (57–78)], IGFBP-3 [2 weeks 74% (63–85); 1 month 69% (62–76); 2–3 months 71% (63–80)], as well as IGFBP-3 protease activity [2 weeks 71% (54–95); 1 month 78% (64–94); 2–3 months 71% (54–93)]. Contrary, the plasma levels (percentage of pretreatment levels with 95 confidence intervals of the mean) of IGFBP-1 [2 weeks 250% (127–495); 1 month 173% (138–542); 2–3 months 273% (146–510)] and IGFBP-4 [2 weeks 146% (112–192); 1 month 140% (116–169); 2–3 months 150% (114–198)] increased significantly. While this study confirms previous observations during treatment with oral oestrogens in substitution doses, the reduction in plasma IGF-II, free IGF-I, IGFBP-2 and -3 are all novel findings. A profound decrease in free IGF-I suggests a reduced bioavailability of IGFs from plasma to the tissues. These observations may be of significance to understand the mechanisms of the antitumour effect of diethylstilboestrol in pharmacological doses. © 2001 Cancer Research Campaign http://www.bjcancer.co

Lack of EGF receptor contributes to drug sensitivity of human germline cells

Germline mutations have been associated with generation of various types of tumour. In this study, we investigated genetic alteration of germline tumours that affect the drug sensitivity of cells. Although all germline tumour cells we tested were hypersensitive to DNA-damaging drugs, no significant alteration was observed in their DNA repair activity or the expression of DNA repair proteins. In contrast, germline tumours expressed very low level of epidermal growth factor receptor (EGFR) compared to drug-resistant ovarian cancer cells. An immunohistochemical analysis indicated that most of the primary germline tumours we tested expressed very low level of EGFR. In accordance with this, overexpression of EGFR in germline tumour cells showed an increase in drug resistance, suggesting that a lack of EGFR, at least in part, contributes to the drug sensitivity of germline tumours