Epidermal Growth Factor Receptor Blockade in Combination with Conventional Chemotherapy Inhibits Soft Tissue Sarcoma Cell Growth In vitro and In vivo

Abstract

Purpose: The epidermal growth factor receptor (EGFR) is highly expressed in many human soft tissue sarcomas (STS). However, EGFR blockade has not apparently been used for human STS therapy; therefore, we examined the in vitro and in vivo effects and the underlying mechanisms before considering EGFR blockade as a therapy for STS patients. Experimental Design: Human STS tissues and cell lines were used to study EGFR expression and activation. Western blot analysis was used to evaluate effects of EGFR activation on downstream signaling. Cell culture assays were used to assess the effect of EGF stimulation as well as EGFR blockade (using an EGFR tyrosine kinase inhibitor, Iressa; AstraZeneca) on STS cell growth, apoptosis, and chemosensitivity. An in vivo study (HT1080 human fibrosarcoma cell line in nude/nude mice: Iressa, doxorubicin, Iressa + doxorubicin, vehicle) was used to examine tumor growth; pEGFR, proliferating cell nuclear antigen, and terminal deoxyribonucleotide transferasem ediated nick-end labeling staining helped assess the effect of therapy in vivo on STS EGFR activation, proliferation, and apoptosis. Results: EGFR was expressed and activated in STS cell lines and tumors, probably due to ligand binding rather than EGFR mutation. Stimulation caused activation of AKTand mitogen-activated protein kinase pathways. EGFR blockade inhibited these effects and also caused increased apoptosis, a p53-independent G 0 -G 1 cell cycle arrest, and decreased cyclin D1 expression. In vivo, Iressa + doxorubicin had markedly synergistic anti-STS effects. Conclusion: EGFR blockade combined with conventional chemotherapy results in anti-human STS activity in vitro and in vivo, suggesting the possibility that combining these synergistic treatments will improve anti-STS therapy.

Disodium Cromolyn and Anti-podoplanin Antibodies Strongly Inhibit Growth of BHK 21/C13-derived Fibrosarcoma in a Chick Embryo Chorioallantoic Membrane Model

“…We observed a similar phenomenon of development and persistence of distant metastases in the specimens treated with disodium cromolyn inhibition of primary tumor but not in those treated with bevacizumab. High EGFR expression of BHK-21/C13 fibrosarcoma is in concordance with previous data showing EGFR expression and modulation in soft-tissue sarcomas cell lines in vitro and in vivo by a combination of gefitinib and doxorubicin (40). These findings support the use of BHK-21/C13 fibroblasts in future research of tumor cell behavior after anti-EGFR agents.…”

Clinical, Pathological, and Molecular Variables Predictive of Malignant Peripheral Nerve Sheath Tumor Outcome

“…1:100;) were used for immunohistochemistry conducted as previously described. 10 Briefly, 4 m thick sections were prepared from the formalin fixed paraffin embedded TMA tissue block and were dried in a oven at 60°for 20 minutes. Ki67, VEGF, p53, and EGFR staining were conducted at the UTMDACC clinical core laboratory, using the dilutions and antigen retrieval conditions listed above.…”

Targeting protein kinases to reverse multidrug resistance in sarcoma

“…The downstream signals predominantly activate the Ras/Raf/MEK/ERK, PI3K/AKT, JNK, signal transducer and activator of transcription (STAT), and PLCγ/PKC pathways, leading to DNA synthesis and regulation cell proliferation, adhesion, and differentiation 11 . EGFR is both overexpressed and activated in various sarcomas, including osteosarcoma, fibrosarcoma, rhabdomyosarcoma, and liposarcoma, which promotes tumor cell progression, activation of downstream signal transduction pathways, resistance to chemotherapeutic drugs, and is associated with poor prognosis 12 . Targeting EGFR with small molecule kinase inhibitors and monoclonal antibodies (mAb) has become a rational targeting strategy for the treatment of sarcoma.…”