Dysfunction of the epidermal growth factor (EGF) complex is essential to the growth and development of many human tumors. Overexpression of the EGF receptor (EGFR) is a characteristic finding in a considerable number of solid tumors and often signalizes poor prognosis. There is a major disagreement among researchers about both the frequency and possible clinical importance of EGFR overexpression in ovarian cancer. The type III variant of EGFR (EGFRvIII) is a mutant with a deletion. Contrary to the wild-type, it is constitutively active. EGFRvIII has not been found in normal tissue, and consequently, it is an attractive tumor-specific candidate for molecular targeted treatment. The literature dealing with this mutation in ovarian cancer has been very sparse.
Tissue from 225 patients who underwent surgery for a pelvic mass was collected consecutively. The samples included 99 ovarian/peritoneal/tuba cancers, 17 ovarian borderline tumors, 66 benign ovarian tumors, 15 other cancer types, 24 normal ovarian biopsies, and 4 miscellaneous. The presence of EGFRvIII was investigated both by PCR analyses for EGFRvIII gene expression and with protein analysis by Western blots.
None of the tissue samples was positive for the EGFRvIII mutation neither at the mRNA level nor at the protein level.
The EGFRvIII mutation seems to be very rare in ovarian tissue. Our data indicate that EGFRvIII is not a part of the malignant phenotype in ovarian cancer and should not be pursued as a therapeutic target for treatment of this disease.
"EGFRvIII can promote cell invasion or epithelial-mesenchymal transition in several cancer types, , , . Previous studies have shown that EGFRvIII can promote EMT or cell invasion by activating STAT3 ,  or regulating myristoylated alanine-rich protein kinase C substrate overexpression. Furthermore, EGFRvIII is expressed in primary breast tumours and contributes to cancer stem cell phenotypes in breast cancer cell lines through the Wnt pathway. "
[Show abstract][Hide abstract] ABSTRACT: Epidermal growth factor receptor (EGFR) is frequently aberrantly expressed in cancer, and abnormal signalling downstream of this receptor contributes to tumour growth. EGFR variant III (EGFRvIII) is the most commonly altered form of EGFR and contains a truncated ligand-binding domain. Aberrant signalling downstream of this receptor contributes to tumour invasion. We previously reported that EGFRvIII can promote hepatocellular carcinoma (HCC) invasion. However, little is known concerning the mechanisms underlying EGFRvIII-mediated increases in cell motility and invasion in HCC. In this study, we observed that S100A11 was significantly upregulated in Huh-7 cells that overexpressed EGFRvIII. Moreover, S100A11 expression was elevated in HCC tissue samples (68.6%; 35/51), and this elevation was correlated with EGFRvIII expression (p = 0.0020; n = 20). Furthermore, the overexpression of S100A11 can promote HCC cell invasiveness, whereas siRNA against S100A11 can suppress the invasiveness of HCC cells stably transfected with EGFRvIII. Additionally, STAT3 inhibitors can block S100A11 expression and S100A11 promoter activity in HCC cells with stable overexpression of EGFRvIII. Furthermore, mutation in STATx binding sites could abolish the S1000A11 promoter activity stimulation by EGFRvIII. Taken together, the results demonstrate that the EGFRvIII-STAT3 pathway promotes cell migration and invasion by upregulating S100A11.
PLoS ONE 12/2013; 8(12):e83332. DOI:10.1371/journal.pone.0083332 · 3.23 Impact Factor
"In this project it was a mutant of EGFR. This mutant is also present in other cancers [23–31]. In this realm, we have efficiently targeted the therapeutic vectors to brain cancer cells (Malecki et al. in prep). "
[Show abstract][Hide abstract] ABSTRACT: Ovarian cancer is the most deadly among all gynecological cancers. Patients undergoing systemic therapies of advanced ovarian cancers suffer from horrendous side effects. Cancer survivors and their offspring suffer from iatrogenic consequences of systemic therapies: genetic mutations. The ultimate goal of our work is development of therapies, which selectively and completely eliminate cancer cells, but do not harm healthy cells. An important consideration for attaining this goal is the fact that ovarian cancer cells over-express EGFR or its mutants, what becomes the factor discriminating them from healthy cells - a potential facilitator of personalized therapy.
The specific aim of this project was threefold: (1) to bioengineer suicide genes' carrying vectors guided by synthetic antibodies for EGFRvIII and EGFR; (2) to genetically engineer DNA constructs for the human, recombinant DNASE1, DNASE1L3, DNASE2, and DFFB controlled by the EGFR promoter; (3) to selectively eradicate ovarian cancer cells by intranuclear targeting of the transgenically expressed recombinant DNases.
Synthetic antibodies for EGFR and EGFRvIII were selected from the human library and used to bioengineer biotag-guided transgenes' vectors. Coding sequences for the human DNASE1, DNASE1L3, DNASE2, DFFB controlled by the EGFR promoter were amplified from the human cDNA and genetically engineered into the plasmid constructs also coding for the fusions with NLS and GFP. The vectors carrying transgenes for the DNases were delivered in vitro into human ovarian cancer cells from ascites and cultures.
Synthetic antibody guided vectors delivered the transgenes for the recombinant DNases efficiently into the ovarian cancer cells. Transgenic expression and nuclear targeting of the DNases in those cells resulted in destruction of their genomes and led to their death, as validated by labeling with the molecular death tags. In healthy cells, which did not over-express EGFR, no changes were recorded.
Targeted expression of the recombinant DNASE1, DNASE1L3, DNASE2, DFFB in the ovarian cancers in vitro resulted in their complete eradication, but had no effects upon the healthy cells. This novel therapeutic strategy has a potential for streamlining it into in vivo trials, as personalized, targeted therapy of ovarian and other cancers.
"Steffensen et al were also unable to detect such mutations. None of the tissues from 225 patients with normal, benign, borderline, or malignant ovarian cancers were positive for the EGFRvIII mutation, either at the mRNA level or at the protein level.64 The consensus at this time is that EGFRvIII mutations are rare in ovarian cancer and do not contribute significantly to the malignant phenotype in this disease. "
[Show abstract][Hide abstract] ABSTRACT: The epidermal growth-factor receptor (EGFR) is overexpressed in the majority of epithelial ovarian cancers and promotes cell proliferation, migration and invasion, and angiogenesis, as well as resistance to apoptosis. This makes EGFR an attractive therapeutic target in this disease. A number of strategies to block EGFR activity have been developed, including small-molecular-weight tyrosine kinase inhibitors such as erlotinib. Erlotinib has been evaluated as a single agent in recurrent ovarian cancer, as well as in combination with chemotherapeutic agents in the first-line and recurrent settings, and in combination with the antiangiogenic agent bevacizumab in the recurrent setting, as well as in the maintenance setting after completion of first-line chemotherapy. Unfortunately, erlotinib has shown only minimal efficacy as a single agent, and it has not enhanced the effects of chemotherapy or bevacizumab when combined with these agents. Ongoing and future studies of erlotinib and other agents blocking EGFR will need to define mechanisms resulting in resistance to such interventions, and to validate biomarkers of response to identify patients most likely to benefit from such approaches.
OncoTargets and Therapy 04/2013; 6:427-35. DOI:10.2147/OTT.S30373 · 2.31 Impact Factor
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