Purpose: Lung cancers with epidermal growth factor receptor (EGFR)–activating mutations show good clinical response to gefitinib and
erlotinib, selective tyrosine kinase inhibitors (TKI) to EGFR, but ...these tumors invariably develop drug resistance. Host stromal
cells have been found to have a considerable effect on the behavior of cancer cells. Little is known, however, about the role
of host cells on the sensitivity of cancer cells to receptor TKIs. We have therefore assessed the effect of crosstalk between
stromal cells and lung cancer cells harboring EGFR mutations on susceptibility to EGFR-TKIs.
Experimental Design: We evaluated the gefitinib sensitivity of lung cancer cells with EGFR-activating mutations, PC-9 and HCC827, when cocultured
with fibroblasts and coinjected into severe combined immunodeficient mice. We also examined the effect of lung cancer cells
to fibroblast recruitment.
Results: Both human fibroblast cell lines and primary cultured fibroblasts produced various levels of hepatocyte growth factor (HGF).
Lung cancer cells markedly recruited fibroblasts. The lung cancer cells became resistant to EGFR-TKIs when cocultured in vitro with HGF-producing fibroblasts and coinjected into severe combined immunodeficient mice. Importantly, combined use of gefitinib
plus anti-HGF antibody or the HGF antagonist, NK4, successfully overcame the fibroblast-induced EGFR-TKI resistance both in vitro and in vivo . Colocalization of fibroblasts and HGF was detected in both xenograft tumors in mouse model and lung cancer patient specimens.
Conclusions: These findings indicate that crosstalk to stromal fibroblasts plays a critical role in lung cancer resistance to EGFR-TKIs
and may be an ideal therapeutic target in lung cancer with EGFR-activating mutations. (Clin Cancer Res 2009;15(21):6630–8)
Small‐cell lung cancer (SCLC) grows rapidly and metastasizes to multiple organs. We examined the antimetastatic effects of the humanized anti‐ganglioside GM2 (GM2) antibodies, BIW‐8962 and KM8927, ...compared with the chimeric antibody KM966, in a SCID mouse model of multiple organ metastases induced by GM2‐expressing SCLC cells. BIW‐8962 and KM8927 induced higher antibody‐dependent cellular cytotoxicity and complement‐dependent cytotoxicity than KM966 against the GM2‐expressing SCLC cell line SBC‐3 in vitro. These humanized antibodies inhibited the production of multiple organ metastases, increased the number of apoptotic cells, and prolonged the survival of the SCID mice. Histological analyses using clinical specimens showed that SCLC cells expressed GM2. These findings suggest that humanized anti‐GM2 antibodies could be therapeutically useful for controlling multiple organ metastases of GM2‐expressing SCLC. (Cancer Sci 2011; 102: 2157–2163)
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Podoplanin (Aggrus), which is a type I transmembrane sialomucin-like glycoprotein, is highly expressed in malignant pleural mesothelioma (MPM). We previously reported the generation of a rat ...anti-human podoplanin Ab, NZ-1, which inhibited podoplanin-induced platelet aggregation and hematogenous metastasis. In this study, we examined the antitumor effector functions of NZ-1 and NZ-8, a novel rat-human chimeric Ab generated from NZ-1 including Ab-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity against MPM in vitro and in vivo. Immunostaining with NZ-1 showed the expression of podoplanin in 73% (11 out of 15) of MPM cell lines and 92% (33 out of 36) of malignant mesothelioma tissues. NZ-1 could induce potent ADCC against podoplanin-positive MPM cells mediated by rat NK (CD161a(+)) cells, but not murine splenocytes or human mononuclear cells. Treatment with NZ-1 significantly reduced the growth of s.c. established tumors of MPM cells (ACC-MESO-4 or podoplanin-transfected MSTO-211H) in SCID mice, only when NZ-1 was administered with rat NK cells. In in vivo imaging, NZ-1 efficiently accumulated to xenograft of MPM, and its accumulation continued for 3 wk after systemic administration. Furthermore, NZ-8 preferentially recognized podoplanin expressing in MPM, but not in normal tissues. NZ-8 could induce higher ADCC mediated by human NK cells and complement-dependent cytotoxicity as compared with NZ-1. Treatment with NZ-8 and human NK cells significantly inhibited the growth of MPM cells in vivo. These results strongly suggest that targeting therapy to podoplanin with therapeutic Abs (i.e., NZ-8) derived from NZ-1 might be useful as a novel immunotherapy against MPM.
Bone metastasis is a critical problem of lung cancer patients. Reproducible animal models of lung cancer bone metastasis, like NK-cell depleted SCID mouse model with SCB-5 cells, are useful to ...explore the molecular mechanism and search of molecular targets. SBC-5 cells overexpressed PTHrP and that treatment with anti-PTHrP neutralizing antibody inhibited the production of bone metastases of SBC-5 cells in the NK-cell depleted SCID mouse model, indicating the critical role of PTHrP in bone metastasis in this model. In addition, we demonstrated that several compounds, including bisphosphonates and reveromycin A, potentially suppress osteoclast-activity were beneficial for the treatments of bone metastasis. Multi-modality therapy may be necessary for further augmenting the therapeutic efficacy against lung cancer bone metastasis.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Small cell lung cancer (SCLC) is aggressive, with rapid growth and frequent bone metastasis; however, its detailed molecular mechanism remains poorly understood. Here, we report the critical role of ...early growth factor 4 (EGR4), a DNA-binding, zinc-finger transcription factor, in cell proliferation of SCLC. EGR4 overexpression in HEK293T cells conferred significant upregulation of specific splice variants of the parathyroid hormone-related protein (PTHrP) gene, resulting in enhancement of the secretion of PTHrP protein, a known mediator of osteolytic bone metastasis. More importantly, depletion of EGR4 expression by siRNA significantly suppressed growth of the SCLC cell lines, SBC-5, SBC-3 and NCI-H1048. On the other hand, introduction of EGR4 into NIH3T3 cells significantly enhanced cell growth. We identified four EGR4 target genes, SAMD5, RAB15, SYNPO and DLX5, which were the most significantly downregulated genes upon depletion of EGR4 expression in all of the SCLC cells examined, and demonstrated the direct recruitment of EGR4 to their promoters by ChIP and luciferase reporter analysis. Notably, knockdown of the expression of these genes by siRNA remarkably suppressed the growth of all the SCLC cells. Taken together, our findings suggest that EGR4 likely regulates the bone metastasis and proliferation of SCLC cells via transcriptional regulation of several target genes, and may therefore be a promising target for the development of anticancer drugs for SCLC patients.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Thymidine phosphorylase (TP), a rate-limiting enzyme in thymidine catabolism, plays a pivotal role in tumor progression; however, the mechanisms underlying this role are not fully understood. Here, ...we found that TP-mediated thymidine catabolism could supply the carbon source in the glycolytic pathway and thus contribute to cell survival under conditions of nutrient deprivation. In TP-expressing cells, thymidine was converted to metabolites, including glucose 6-phosphate, lactate, 5-phospho-α-D-ribose 1-diphosphate, and serine, via the glycolytic pathway both in vitro and in vivo. These thymidine-derived metabolites were required for the survival of cells under low-glucose conditions. Furthermore, activation of thymidine catabolism was observed in human gastric cancer. These findings demonstrate that thymidine can serve as a glycolytic pathway substrate in human cancer cells.
Display omitted
•Thymidine catabolism can supply carbon for glycolysis•TP-expressing cancer cells are resistant to nutrient starvation•Thymidine-derived metabolites enter glycolysis in a physiological context•Thymidine is catabolized to lactate in TP-expressing tumor xenografts
Tabata et al. find that thymidine phosphorylase (TP)-mediated thymidine catabolism can supply carbon to the glycolytic pathway in mammalian cells. In TP-expressing cancer cells, thymidine contributes to cell survival under nutrient starvation.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Purpose: The secondary T790M mutation in epidermal growth factor receptor ( EGFR ) is the most frequent cause of acquired resistance to the reversible EGFR tyrosine kinase inhibitors (EGFR-TKI), ...gefitinib
and erlotinib, in lung cancer. Irreversible EGFR-TKIs are expected to overcome the reversible EGFR-TKI resistance of lung
cancer harboring T790M mutation in EGFR . However, it is clear that resistance may also develop to this class of inhibitors. We showed previously that hepatocyte
growth factor (HGF) induced gefitinib resistance of lung cancer harboring EGFR -activating mutations. Here, we investigated whether HGF induced resistance to the irreversible EGFR-TKI, CL-387,785, in lung
cancer cells (H1975) harboring both L858R activating mutation and T790M secondary mutation in EGFR .
Experimental Design: CL-387,785 sensitivity and signal transduction in H1975 cells were examined in the presence or absence of HGF or HGF-producing
fibroblasts with or without HGF-MET inhibitors.
Results: HGF reduced susceptibility to CL-387,785 in H1975 cells. Western blotting and small interfering RNA analyses indicated that
HGF-induced hyposensitivity was mediated by the MET/phosphoinositide 3-kinase/Akt signaling pathway independent of EGFR, ErbB2,
ErbB3, and ErbB4. Hyposensitivity of H1975 cells to CL-387,785 was also induced by coculture with high-level HGF-producing
lung fibroblasts. The hyposensitivity was abrogated by treatment with anti-HGF neutralizing antibody, HGF antagonist NK4,
or MET-TKI.
Conclusions: We showed HGF-mediated hyposensitivity as a novel mechanism of resistance to irreversible EGFR-TKIs. It will be clinically
valuable to investigate the involvement of HGF-MET–mediated signaling in de novo and acquired resistance to irreversible EGFR-TKIs in lung cancer harboring T790M mutation in EGFR . Clin Cancer Res; 16(1); 174–83
Acquired resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) is a serious problem in the management of EGFR mutant lung cancer. We recently reported that ...hepatocyte growth factor (HGF) induces resistance to EGFR-TKIs by activating the Met/PI3K pathway. HGF is also known to induce angiogenesis in cooperation with vascular endothelial growth factor (VEGF), which is an important therapeutic target in lung cancer. Therefore, we hypothesized that dual inhibition of HGF and VEGF may be therapeutically useful for controlling HGF-induced EGFR-TKI–resistant lung cancer. We found that a dual Met/VEGF receptor 2 kinase inhibitor, E7050, circumvented HGF-induced EGFR-TKI resistance in EGFR mutant lung cancer cell lines by inhibiting the Met/Gab1/PI3K/Akt pathway in vitro . HGF stimulated VEGF production by activation of the Met/Gab1 signaling pathway in EGFR mutant lung cancer cell lines, and E7050 showed an inhibitory effect. In a xenograft model, tumors produced by HGF-transfected Ma-1 (Ma-1/HGF) cells were more angiogenic than vector control tumors and showed resistance to gefitinib. E7050 alone inhibited angiogenesis and retarded growth of Ma-1/HGF tumors. E7050 combined with gefitinib induced marked regression of tumor growth. Moreover, dual inhibition of HGF and VEGF by neutralizing antibodies combined with gefitinib also markedly regressed tumor growth. These results indicate the therapeutic rationale of dual targeting of HGF-Met and VEGF–VEGF receptor 2 for overcoming HGF-induced EGFR-TKI resistance in EGFR mutant lung cancer.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Imatinib mesylate is a potent and specific tyrosine kinase inhibitor against c-ABL, BCR-ABL, and c-KIT, and has been demonstrated to be highly active in chronic myeloid leukemia and gastrointestinal ...stromal tumors. We examined the antifibrotic effects of imatinib using a bleomycin-induced lung fibrosis model in mice because imatinib also inhibits tyrosine kinase of platelet-derived growth factor receptors (PDGFRs). Imatinib inhibited the growth of primary murine lung fibroblasts and the autophosphorylation of PDGFR-beta induced by PDGF. Administration of imatinib significantly prevented bleomycin-induced pulmonary fibrosis in mice, partly by reducing the number of mesenchymal cells incorporating bromodeoxyuridine. Analysis of bronchoalveolar lavage cells demonstrated that imatinib did not suppress early inflammation on Days 7 and 14 caused by bleomycin. These results suggest that imatinib has the potential to prevent pulmonary fibrosis by inhibiting the proliferation of mesenchymal cells, and that imatinib might be useful for the treatment of pulmonary fibrosis in humans.
Focal adhesion kinase (FAK) is a nonreceptor tyrosine kinase involved in various biological functions, including cell survival, proliferation, migration, and adhesion. FAK is an essential factor for ...transforming growth factor β to induce myofibroblast differentiation. In the present study, we investigated whether the targeted inhibition of FAK by using a specific inhibitor, TAE226, has the potential to regulate pulmonary fibrosis. TAE226 showed inhibitory activity of autophosphorylation of FAK at tyrosine 397 in lung fibroblasts. The addition of TAE226 inhibited the proliferation of lung fibroblasts in response to various growth factors, including platelet-derived growth factor and insulin-like growth factor I, in vitro. TAE226 strongly suppressed the production of type I collagen by lung fibroblasts. Furthermore, treatment of fibroblasts with TAE226 reduced the expression of α-smooth muscle actin induced by transforming growth factor β, indicating the inhibition of differentiation of fibroblasts to myofibroblasts. Administration of TAE226 ameliorated the pulmonary fibrosis induced by bleomycin in mice even when used late in the treatment. The number of proliferating mesenchymal cells was reduced in the lungs of TAE226-treated mice. These data suggest that FAK signal plays a significant role in the progression of pulmonary fibrosis and that it can become a promising target for therapeutic approaches to pulmonary fibrosis.
PDF
