Selective toxicity of TGF-alpha-PE40 to EGFR-positive cell lines: selective protection of low EGFR-expressing cell lines by EGF

An EGF receptor-targeting amphinase recombinant protein mediates anti-tumor activity in vitro and in vivo

Utilizing cytotoxic proteins linked to tumor targeting molecules as anti-tumor drugs is a promising approach. However, most cytotoxins derived from bacteria or plants have inherent problems such as large molecular weights and they trigger a strong immune system reaction, which leads to drug failure and serious side effects. Amphinase (Amph) is a ribonuclease with a low molecular weight that is found in northern leopard frog oocytes. It has strong cytotoxicity against tumor cell lines in vitro and weak immunogenicity in vivo, and is a promising candidate in the development of targeted drugs. Transforming growth factor-α (TGF-α) that binds to the epidermal growth factor receptor (EGFR) is being used as a targeting molecule for the treatment of EGFR high-expressing tumors. In this study, we expressed and purified a recombinant amphinase and its TGF-α fusion protein (AGT) separately from Escherichia coli. AGT exhibited more significant cytotoxicity in vitro on EGFR high-expressing tumor cell lines, and stronger anti-tumor effects in vivo. This fusion protein also exhibited unusual thermostability, low in vivo immunogenicity, and side effects. Our results provide a new entry point for the development of novel, highly efficient anti-tumor targeting biological agents with low immunogenicity.

Theranostic Gold Nanoantennas for Simultaneous Multiplexed Raman Imaging of Immunomarkers and Photothermal Therapy

In this study, we demonstrate the theranostic capability of actively targeted, site-specific multibranched gold nanoantennas (MGNs) in triple-negative breast cancer (TNBC) cells in vitro. By utilizing multiplexed surface-enhanced Raman scattering (SERS) imaging, enabled by the narrow peak widths of Raman signatures, we simultaneously targeted immune checkpoint receptor programmed death ligand 1 (PDL1) and the epidermal growth factor receptor (EGFR) overexpressed in TNBC cells. A 1:1 mixture of MGNs functionalized with anti-PDL1 antibodies and Raman tag 5,5-dithio-bis-(2-nitrobenzoic acid) (DTNB) and MGNs functionalized with anti-EGFR antibodies and Raman tag para-mercaptobenzoic acid (pMBA) were incubated with the cells. SERS imaging revealed a cellular traffic map of MGN localization by surface binding and receptor-mediated endocytosis, enabling targeted diagnosis of both biomarkers. Furthermore, cells incubated with anti-EGFR-pMBA-MGNs and illuminated with an 808 nm laser for 15 min at 4.7 W/cm² exhibited photothermal cell death only within the laser spot (indicated by live/dead cell fluorescence assay). Therefore, this study not only provides an optical imaging platform that can track immunomarkers with spatiotemporal control but also demonstrates an externally controlled light-triggered therapeutic approach enabling receptor-specific treatment with biocompatible theranostic nanoprobes.

Recombinant Immunotoxin Therapy of Glioblastoma: Smart Design, Key Findings, and Specific Challenges

Recombinant immunotoxins (RITs) refer to a group of recombinant protein-based therapeutics, which consists of two components: an antibody variable fragment or a specific ligand that allows RITs to bind specifically to target cells and an engineered toxin fragment that kills the target cells upon internalization. To date, over 1,000 RITs have been generated and significant success has been achieved in the therapy of hematological malignancies. However, the immunogenicity and off-target toxicities of RITs remain as significant barriers for their application to solid tumor therapy. A group of RITs have also been generated for the treatment of glioblastoma multiforme, and some have demonstrated evidence of tumor response and an acceptable profile of toxicity and safety in early clinical trials. Different from other solid tumors, how to efficiently deliver the RITs to intracranial tumors is more critical and needs to be solved urgently. In this article, we first review the design and expression of RITs, then summarize the key findings in the preclinical and clinical development of RIT therapy of glioblastoma multiforme, and lastly discuss the specific issues that still remain to forward RIT therapy to clinical practice.

EGFR-targeted Chimeras of Pseudomonas ToxA released into the extracellular milieu by attenuated Salmonella selectively kill tumor cells

Tumor-targeted Salmonella VNP20009 preferentially replicate within tumor tissue and partially suppress tumor growth in murine tumor models. These Salmonella have the ability to locally induce apoptosis when they are in direct contact with cancer cells but they lack significant bystander killing, which may correlate with their overall lack of antitumor activity in human clinical studies. In order to compensate for this deficiency without enhancing overall toxicity, we engineered the bacteria to express epidermal growth factor receptor (EGFR)-targeted cytotoxic proteins that are released into the extracellular milieu. In this study, we demonstrate the ability of the Salmonella strain VNP20009 to produce three different forms of the Pseudomonas exotoxin A (ToxA) chimeric with a tumor growth factor alpha (TGFα) which results in its producing culture supernatants that are cytotoxic and induce apoptosis in EGFR positive cancer cells as measured by the tetrazolium dye reduction, and Rhodamine 123 and JC-10 mitochondrial depolarization assays. In addition, exchange of the ToxA REDLK endoplasmic reticulum retention signal for KDEL and co-expression of the ColE3 lysis protein resulted in an overall increased cytotoxicity compared to the wild type toxin. This approach has the potential to significantly enhance the antitumor activity of VNP20009 while maintaining its previously established safety profile. Biotechnol. Bioeng. 2016;113: 2698-2711. © 2016 The Authors. Biotechnology and Bioengineering published by Wiley Periodicals, Inc.

Interaction between the epidermal growth factor receptor (EGFR) and the vascular endothelial growth factor (VEGF) pathways: a rational approach for multi-target anticancer therapy

Over the last decade, the concept of targeted biological therapy for the treatment of cancer has emerged. However, a better understanding of these targets and their role in tumor cells and in the surrounding stromal cells is required. Two interesting biological targets are the epidermal growth factor receptor (EGFR) and the vascular endothelia growth factor (VEGF) and its receptors. A number of agents that target these pathways have been described. Many of these are currently in clinical trials and a few have recently been approved by the regulatory authorities in USA and in the European Union. The molecular pathways involved in the proliferation of cancer cells and in tumor-related angiogenesis are very complex and the interference with only a single step of these pathways may often reveal an insufficient therapeutic approach. Moreover, cancer cells have an inherent ability to harness different growth factor signaling pathways for growth advantage and cell survival, a process that may even be facilitated by the use of selective targeted agents. Because of these escape mechanisms, monotherapy with selective targeted agents is unlikely to be a fully effective cancer treatment. For these reasons, targeting different pathways is an attractive and effective therapeutic strategy with a strong rationale for investigating this approach in the clinic. This review focuses on the preclinical rationale of combining targeted agents such as EGFR and VEGF inhibitors in the treatment of cancer and on the clinical trials that have emerged from these studies.

Expression of ERRP in normal and neoplastic pancreata and its relationship to clinicopathologic parameters in pancreatic adenocarcinoma

INTRODUCTION AND AIMS

Epidermal growth factor (EGF) and its receptor (EGFR) play crucial roles in cellular signaling in many malignancies, including pancreatic neoplasia. Attenuation of EGFR signaling has been considered novel strategy for the management of human malignancies in several ongoing clinical trials. We recently isolated a novel negative regulator of EGFR, termed EGF receptor related protein (ERRP), whose expression appears to attenuate EGFR activation. In the current study, the expression of ERRP in normal and neoplastic pancreas was investigated and correlated with the clinicopathologic parameters in pancreatic ductal adenocarcinoma (DA).

METHODOLOGY

Using rabbit polyclonal antibody that specifically interacts with ERRP, immunohistochemical staining was performed on 45 benign pancreata and 106 cases of DA. The intensity and percentage of cells with cytoplasmic and membranous staining were scored as 0, 1, 2, or 3. A combined score was calculated as intensity x percent/3, and for comparative analysis, the data were arbitrarily divided into three groups: <20, 20-49, and > or =50. The expression of ERRP was correlated with patient age, gender, race, tumor size, stage, grade, and survival.

RESULTS

ERRP was expressed in most benign ductal epithelium and islet cells, but not in normal acinar cells. In pancreatic ductal adenocarcinoma, ERRP expression frequency decreased progressively from well (WD) to moderate (MD) to poorly differentiated (PD) carcinoma (58%, 43%, and 15% respectively, < 0.001). ERRP expression was correlated with survival in DA showing decreased median survival with decreased ERRP score ( = 0.0035). Median survival of the lower intensity (0 or 1) group was less than that of the higher intensity (2 or 3) group (8 14 months, = 0.002). The higher expressing group (> or =50% of cells) had longer median survival (17 months) than the lower expressing (<50% of cells) group (10 months, = 0.003). Stepwise multiple regression analyses revealed that ERRP expression score and tumor grade are the significant predictors of survival in pancreatic ductal carcinomas ( < 0.03).

CONCLUSION

ERRP is usually expressed in benign ductal epithelium, but not in ductal adenocarcinoma. Its expression decreases with decreasing tumor differentiation. Low levels of ERRP are associated with poor clinical outcome, suggesting that progressive loss of ERRP, a negative regulator of EGFR, may partly stimulate aggressive tumor cell growth in pancreatic adenocarcinoma.

Cooperative inhibition of renal cancer growth by anti-epidermal growth factor receptor antibody and protein kinase A antisense oligonucleotide

BACKGROUND

The expression of epidermal growth factor receptor (EGFR) and type I cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKAI) is associated with neoplastic transformation. By use of human renal cancer cell lines (i.e., 769-P, ACHN, A498, and SW839), we investigated the antiproliferative activity and the antitumor activity of an anti-EGFR humanized chimeric mouse monoclonal antibody, MAb C225, and a novel mixed backbone 18-mer antisense oligonucleotide, HYB 190, that targets expression of the RIalpha regulatory subunit of PKAI.

METHODS

The antiproliferative activity of MAb C225 and oligonucleotide HYB 190, alone or in combination, on different renal cancer cell lines was determined by monitoring cell growth in soft agar. In addition, the induction of apoptosis by treatment with the anti-EGFR antibody and/or antisense PKAI oligonucleotides was evaluated by flow cytometric analysis of fragmented DNA. The antitumor activity of MAb C225 and oligonucleotide HYB 190 was determined in athymic mice bearing established ACHN tumor xenografts. Cell proliferation and tumor growth data were evaluated for statistical significance using Student's t test; reported P values are two-sided.

RESULTS

MAb C225 and oligonucleotide HYB 190 inhibited colony formation in soft agar in a dose-dependent manner for all renal cancer cell lines tested. We observed a potentiation of growth inhibition and induction of apoptosis when 769-P cells and ACHN cells were treated with both agents. Combination treatment with MAb C225 and oligonucleotide HYB 190 caused regression of ACHN tumor xenografts, whereas single-agent treatment only delayed tumor growth.

CONCLUSION

The combination of anti-EGFR MAb C225 and ited cooperative antiproliferative effects and cooperative antitumor effects on EGFR and PKAI-expressing human renal cancer cell lines.

The epidermal growth factor receptor in breast cancer

The epidermal growth factor receptor (EGFR)3 is a 170 kD transmembrane tyrosine kinase activated by several ligands. It is required for normal mammary development and lactation and is aberrantly expressed in approximately 40% of breast carcinomas, particularly those with a poor prognostic phenotype. Since EGF receptor levels are elevated in a high proportion of many tumor types its potential as a therapy target is being investigated using the EGF receptor to target toxins, as well as drugs that interfere with signaling and anti-receptor antibodies. These approaches are likely to be most effective when used in the adjuvant situation in combination with chemotherapy.

Prognostic value of epidermal growth factor expression in breast cancer

A series of 198 female breast cancer biopsies were analysed immunohistochemically for the expression of epidermal growth factor (EGF), with special emphasis on its prognostic significance. A total of 67/198 tumours (33.8%) were EGF-positive, 24 (12%) of which showed strong expression of EGF. EGF was usually expressed in the cytoplasm of the cancer cells but, in 22 cases, the normal ducts adjacent to the cancer showed positive staining as well. Strong EGF expression was related to distant metastases at diagnosis (P = 0.04). Oestrogen(ER)- and progesterone-receptor(PR)-negative tumours showed EGF positivity with equal frequency (P = 0.05 in both). Axillary lymph node status, histological type, tumour size, histological grade, S-phase fraction, mitotic index or cancer recurrence did not show any statistical correlation with EGF expression. Tumour size (P = 0.007), axillary lymph node involvement (P = 0.003) and ER content (P = 0.03) were independent prognostic factors in multivariate survival analysis, whereas EGF positivity, as an independent factor, had no effect on survival. In univariate analysis, however, EGF positivity predicted a more favourable outcome in axillary-lymph-node-positive tumours (P = 0.04). The results suggest that immunohistochemical assessment of EGF expression has hardly any clinical significance in addition to the well-established prognostic factors in breast cancer.

The epidermal growth factor receptor and its ligands as therapeutic targets in human tumors

The epidermal growth factor receptor (EGFR) is detected on many non-haematopoietic tissues and is frequently overexpressed in human tumors. With its ligand, TGF-alpha, it forms a well-defined autocrine growth loop. Several clinical approaches, using EGFR as a therapeutic target, are being investigated, particularly monoclonal antibodies combined with chemotherapy, and pharmacological inhibition of downstream components of the EGFR signaling pathway.

Targeting the epidermal growth factor receptor for therapy of carcinomas

As a group, the carcinomas represent a substantial proportion of all human malignancies, but, with relatively few exceptions, current treatments are ineffective. Modification of existing chemotherapeutic agents has not led to significant improvements in the survival of carcinoma patients, and development of new therapeutic strategies is imperative. It is now becoming apparent that activation of the epidermal growth factor receptor (EGF-R) has much wider implications than a straightforward stimulation of cell division. The pleiotropic effects of EGF-R signalling may influence tumour behaviour and the response of carcinomas to treatment; these are important considerations for the development of new therapies that aim to exploit the expression or modulate the function of the EGF-R in these tumours.