ABSTRACT
Tumor budding has been found to be of prognostic significance for several cancers, including colorectal cancer (CRC). Additionally, the molecular classification of CRC has led to the identification of different immune microenvironments linked to distinct prognosis and therapeutic response. However, the association between tumor budding and the different molecular subtypes of CRC and distinct immune profiles have not been fully elucidated. This study focused, firstly, on the validation of derived xenograft models (PDXs) for the evaluation of tumor budding and their human counterparts and, secondly, on the association between tumor budding and the immune tumor microenvironment by the analysis of gene expression signatures of immune checkpoints, Toll-like receptors (TLRs), and chemokine families. Clinical CRC samples with different grades of tumor budding and their corresponding PDXs were included in this study. Tumor budding grade was reliably reproduced in early passages of PDXs, and high-grade tumor budding was intimately related with a poor-prognosis CMS4 mesenchymal subtype. In addition, an upregulation of negative regulatory immune checkpoints (PDL1, TIM-3, NOX2, and IDO1), TLRs (TLR1, TLR3, TLR4, and TLR6), and chemokine receptors and ligands (CXCR2, CXCR4, CXCL1, CXCL2, CXCL6, and CXCL9) was detected in high-grade tumor budding in both human samples and their corresponding xenografts. Our data support a close link between high-grade tumor budding in CRC and a distinctive immune-suppressive microenvironment promoting tumor invasion, which may have a determinant role in the poor prognosis of the CMS4 mesenchymal subtype. In addition, our study demonstrates that PDX models may constitute a robust preclinical platform for the development of novel therapies directed against tumor budding in CRC.
ABSTRACT
OBJECTIVE: Aberrant activation of tyrosine kinase receptors is frequently observed in acute myelogenous leukemia (AML). Moreover, activating mutations of the fms-like tyrosine kinase 3 (FLT3) receptor can be found in approximately 30% of patients, thereby representing one of the most frequent single genetic alterations in AML. AEE788, a novel dual receptor tyrosine kinase inhibitor of endothelial growth factor and vascular endothelial growth factor (VEGF), is being studied in several solid tumors with remarkable success. It is not known, however, about the efficacy of this inhibitor in the treatment of AML. Therefore, we investigated the effect of AEE788 in the treatment of three human AML cell lines and seven AML patient samples. MATERIALS AND METHODS: Cell survival in THP-1, MOLM-13, and MV4-11 cell lines (the two last harboring the FLT3/internal tandem duplication mutation) and AML blasts incubated with 0.5 to 15 microM AEE788 were quantified. We also studied the activation of VEGF/VEGF receptors loop, FLT3, and their downstream effectors (Akt, extracellular signal-regulated kinase, signal transducers and activators of transcription 5, and nuclear factor-kappaB). RESULTS: Our data showed that AEE788 was a tyrosine kinase inhibitor of FLT3 activity and had antiproliferative and proapoptotic activity in AML-derived cell lines and AML blasts that presented phosphorylation of the FLT3 receptor. Consistently, in these cells AEE788 abrogated VEGF/VEGF receptors activation and the survival signaling pathways studied. CONCLUSION: Taken together, the activity of AEE788 might represent a promising new option of targeting FLT3 for the treatment of AML.
Subject(s)
Apoptosis/drug effects , Cell Proliferation/drug effects , Leukemia, Myeloid, Acute/drug therapy , Protein Kinase Inhibitors/pharmacology , Purines/pharmacology , fms-Like Tyrosine Kinase 3/antagonists & inhibitors , Cell Line, Tumor , Cell Survival/drug effects , Drug Screening Assays, Antitumor , Humans , Leukemia, Myeloid, Acute/enzymology , Leukemia, Myeloid, Acute/genetics , Mutation , NF-kappa B/genetics , NF-kappa B/metabolism , Proto-Oncogene Proteins c-akt/genetics , Proto-Oncogene Proteins c-akt/metabolism , STAT5 Transcription Factor/genetics , STAT5 Transcription Factor/metabolism , Signal Transduction/drug effects , Vascular Endothelial Growth Factor A/genetics , Vascular Endothelial Growth Factor A/metabolism , fms-Like Tyrosine Kinase 3/genetics , fms-Like Tyrosine Kinase 3/metabolismABSTRACT
Acute myeloid leukemia (AML) is a disease with a poor prognosis. It has been demonstrated that AML cells express vascular endothelial growth factor (VEGF) as well as Flt-1 and KDR, resulting in an autocrine pathway for cell survival. PTK787/ZK 222584 is a new oral antiangiogenic molecule that inhibits tyrosine kinase activity of all known VEGF receptors. The present study aimed to investigate the therapeutic efficacy of combining PTK787/ZK 222584 with a chemotherapeutic agent, such as Idarubicin, for treatment of AML. We have analyzed in four AML cell lines and seven AML patient samples, cell proliferation, apoptosis, angiogenesis. and activation of several related intracellular pathways after treatment with PTK787/ZK 222584 alone or combined with Idarubicin. PTK787/ZK 222584 decreased VEGF levels and VEGF receptor phosphorylation in the AML cells showing Fms-like tyrosine kinase 3/internal tandem duplication mutation (Flt3/ITD). Both drugs, given separately, inhibited cell proliferation and promoted apoptosis. Moreover, combined treatment promoted more apoptosis and inhibition of cell proliferation than each compound administered separately in all AML cells. In conclusion, PTK787/ZK 222584 combined with Idarubicin achieved a better therapeutic efficacy than chemotherapy alone in AML cells, especially in those with Flt3/ITD, in which the combination further prevented activation of the angiogenic process.
