ZD6474, a vascular endothelial growth factor receptor tyrosine kinase inhibitor with additional activity against epidermal growth factor receptor tyrosine kinase, inhibits orthotopic growth and angiogenesis of gastric cancer

Role and mechanistic actions of protein kinase inhibitors as an effective drug target for cancer and COVID

Kinases can be grouped into 20 families which play a vital role as a regulator of neoplasia, metastasis, and cytokine suppression. Human genome sequencing has discovered more than 500 kinases. Mutations of the kinase itself or the pathway regulated by kinases leads to the progression of diseases such as Alzheimer's, viral infections, and cancers. Cancer chemotherapy has made significant leaps in recent years. The utilization of chemotherapeutic agents for treating cancers has become difficult due to their unpredictable nature and their toxicity toward the host cells. Therefore, targeted therapy as a therapeutic option against cancer-specific cells and toward the signaling pathways is a valuable avenue of research. SARS-CoV-2 is a member of the Betacoronavirus genus that is responsible for causing the COVID pandemic. Kinase family provides a valuable source of biological targets against cancers and for recent COVID infections. Kinases such as tyrosine kinases, Rho kinase, Bruton tyrosine kinase, ABL kinases, and NAK kinases play an important role in the modulation of signaling pathways involved in both cancers and viral infections such as COVID. These kinase inhibitors consist of multiple protein targets such as the viral replication machinery and specific molecules targeting signaling pathways for cancer. Thus, kinase inhibitors can be used for their anti-inflammatory, anti-fibrotic activity along with cytokine suppression in cases of COVID. The main goal of this review is to focus on the pharmacology of kinase inhibitors for cancer and COVID, as well as ideas for future development.

In silico studies of a novel scaffold of benzoxazole derivatives as anticancer agents by 3D-QSAR, molecular docking and molecular dynamics simulations

The vascular endothelial growth factor receptor-2 kinases (VEGFR-2) expressed on tumor cells and vessels are attractive targets for cancer treatment. Potent inhibitors for the VEGFR-2 receptor are novel strategies to develop anti-cancer drugs. In this work, template ligand-based 3D-QSAR studies were performed on a series of benzoxazole derivatives toward different cell lines (HepG2, HCT-116 and MCF-7). Comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) techniques were used to generate 3D-QSAR models. Good predictability was derived for the optimal CoMFA models (HepG2: R_cv² = 0.509, R_pred² = 0.5128; HCT-116: R_cv² = 0.574, R_pred² = 0.5597; MCF-7: R_cv² = 0.568, R_pred² = 0.5057) and CoMSIA models (HepG2: R_cv² = 0.711, R_pred² = 0.6198; HCT-116: R_cv² = 0.531, R_pred² = 0.5804; MCF-7: R_cv² = 0.669, R_pred² = 0.6577). In addition, the contour maps derived from CoMFA and CoMSIA models were also generated to illustrate the relationship between different fields and the inhibitory activities. Moreover, molecular docking and molecular dynamics (MD) simulations were also conducted to understand the binding modes and the potential interactions between the receptor and the inhibitors. Some key residues (Leu35, Val43, Lys63, Leu84, Gly117, Leu180 and Asp191) were pointed out for stabilizing the inhibitors in the binding pocket. The binding free energies for the inhibitors agreed well with the experimental inhibitory activity and indicated that steric, electrostatic and hydrogen bond interactions are the main driving force for inhibitor-receptor binding. Overall, a good consistency between theoretical 3D-SQAR and molecular docking and MD simulation studies would provide directions for the design of new candidates, avoiding time-consuming and costly synthesis and biological evaluations. On the whole, the results derived from this study could expand the understanding of benzoxazole derivatives as anticancer agents and would be of great help in lead optimization for early drug discovery of highly potent anticancer activity targeting VEGFR-2.

The promising role of monoclonal antibodies for gastric cancer treatment

Gastric cancer (GC) is the second leading cause of cancer-related death world-wide. Despite improvements in prevention, early detection and various therapeutic options, the prognosis is still poor. GC is often diagnosed at an advanced stage with survivals less than 1 year. Chemotherapy as the mainstay of treatment in advanced stage is not of notable advantages, underlining the need for novel more effective therapeutic options. Based on current knowledge of molecular and cellular mechanisms, a number of novel biologic approaches such as monoclonal antibodies have been recently introduced for cancer treatment that mainly affect the immune system or target signaling pathways playing role in cancer and metastasis development. In this review, various monoclonal antibodies for GC therapy were explained.

A Drosophila Based Cancer Drug Discovery Framework

In recent years, there has been growing interest in using Drosophila for drug discovery as it provides a unique opportunity to screen small molecules against complex disease phenotypes in a whole animal setting. Furthermore, gene-compound interaction experiments that combine compound feeding with complex genetic manipulations enable exploration of compound mechanisms of response and resistance to an extent that is difficult to achieve in other experimental models. Here, I discuss how compound screening and testing approaches reported in Drosophila fit into the current cancer drug discovery pipeline. I then propose a framework for a Drosophila-based cancer drug discovery strategy which would allow the Drosophila research community to effectively leverage the power of Drosophila to identify candidate therapeutics and push our discoveries into the clinic.

Vandetanib, an inhibitor of VEGF receptor-2 and EGF receptor, suppresses tumor development and improves prognosis of liver cancer in mice

PURPOSE

VEGF, EGF, and TGF-α are expressed in hepatocellular carcinomas (HCC) and play a role in its growth. Vandetanib, a multikinase inhibitor, suppresses the phosphorylation of VEGF receptor 2 (VEGFR-2) and EGF receptor (EGFR). The aim of this study was to clarify the antitumor effect of vandetanib in mouse HCCs.

EXPERIMENTAL DESIGN

We evaluated the effects of vandetanib on proliferation of human umbilical vein endothelial cells (HUVEC) and three hepatoma cell lines, as well as the phosphorylation of VEGFR-2 and EGFR in these cells. Mice were implanted with hepatoma cells subcutaneously or orthotopically in the liver and treated with 50 or 75 mg/kg vandetanib. We analyzed the effects of treatment on tumor cell proliferation and apoptosis, vessel density, phosphorylation of VEGFR-2 and EGFR, and production of VEGF, TGF-α, and EGF in tumor tissues. Adverse events on vandetanib administration were also investigated.

RESULTS

Vandetanib suppressed phosphorylation of VEGFR-2 in HUVECs and EGFR in hepatoma cells and inhibited cell proliferation. In tumor-bearing mice, vandetanib suppressed phosphorylation of VEGFR-2 and EGFR in tumor tissues, significantly reduced tumor vessel density, enhanced tumor cell apoptosis, suppressed tumor growth, improved survival, reduced number of intrahepatic metastases, and upregulated VEGF, TGF-α, and EGF in tumor tissues. Treatment with vandetanib was not associated with serious adverse events, including alanine aminotransferase abnormality, bone marrow suppression, or body weight loss.

CONCLUSIONS

The antitumor effects of vandetanib in mice suggest that it is a potentially suitable and safe chemotherapeutic agent for HCCs.

Combined vascular endothelial growth factor receptor/epidermal growth factor receptor blockade with chemotherapy for treatment of local, uterine, and metastatic soft tissue sarcoma

PURPOSE

Soft tissue sarcoma (STS) is a rare heterogeneous malignancy. Overall survival has been stagnant for decades, primarily because systemic therapies are ineffective versus metastases, the leading cause of STS lethality. Consequently, we examined whether tyrosine kinase receptors active in STS growth signaling might be blockable and whether multireceptor blockade might synergize with low-dose STS chemotherapy by therapeutically affecting STS cells and their associated microenvironment.

EXPERIMENTAL DESIGN

Vandetanib (AstraZenca), a tyrosine kinase inhibitor of vascular endothelial growth factor receptor 2 and epidermal growth factor receptor, was evaluated alone and with chemotherapy in vitro and in vivo in three human STS nude mouse xenograft models of different STS locations (muscle, uterus, lung), stages (primary, metastatic), and subtypes (leiomyosarcoma, fibrosarcoma, uterine sarcoma: luciferase-expressing MES-SA human uterine sarcoma cells surgically implanted into uterine muscularis with bioluminescence tumor growth assessment; developed by us).

RESULTS

In vitro, human STS cells were sensitive to vandetanib. Vandetanib alone and with chemotherapy statistically significantly inhibited leiomyosarcoma local growth and fibrosarcoma lung metastasis. Direct injection of MES-SA into nude mice uterine muscularis resulted in high tumor take (88%), whereas s.c. injection resulted in no growth, suggesting microenvironmental tumor growth modulation. Vandetanib alone and with chemotherapy statistically significantly inhibited uterine sarcoma growth. In all models, vandetanib induced increased apoptosis, decreased tumor cell proliferation, and decreased angiogenesis.

CONCLUSIONS

Vandetanib has antitumor effects against human STS subtypes in vitro and in vivo, where it also affects the tumor-associated microenvironment. Given the urgent need for better systemic approaches to STS, clinical trials evaluating vandetanib, perhaps with low-dose chemotherapy, seem warranted.

Induction of cell cycle arrest and apoptosis in human nasopharyngeal carcinoma cells by ZD6474, an inhibitor of VEGFR tyrosine kinase with additional activity against EGFR tyrosine kinase

ZD6474 is a vascular endothelial growth factor receptor (VEGFR) and epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor. The present study was undertaken to investigate the direct antiproliferative effect of ZD6474 on human nasopharyngeal carcinoma (NPC) in vitro and the antitumor activity on NPC xenografts in vivo. Results indicated that ZD6474 treatment inhibited EGFR phosphorylation and led to a dose- and time-dependent decrease in NPC cell (CNE-1, CNE-2 and C666-1) proliferation. Further investigation demonstrated G0/G1 cell cycle arrest in all 3 cell lines, which was associated with an upregulation of p21 and/or p27, and downregulation of CDK4, CDK6 and CDK2. ZD6474 treatment also induced apoptosis in CNE-1 and CNE-2 cells. The apoptosis mechanisms involved reduction of Bcl-2 and/or Bcl-XL, induction of Bak and/or Bax, and activation of caspases-3, -9 and/or -8. The in vivo antitumor activity was evaluated in CNE-2 and C666-1 xenografted nude mice. Administration of ZD6474 (25-100 mg/kg/day, once-daily, p.o.) produced a dose-dependent inhibition of tumor growth and prolonged survival in both models. This study suggests that ZD6474 exerts direct antiproliferative effects on NPC cell lines in vitro by inducing G0/G1 arrest and apoptosis, and potent antitumor effects on NPC xenografts in vivo. It indicates that ZD6474 may offer a new and effective treatment for human NPC.

Vascular endothelial growth factor overexpression by soft tissue sarcoma cells: implications for tumor growth, metastasis, and chemoresistance

To better elucidate the role of vascular endothelial growth factor (VEGF)(165) in soft tissue sarcoma (STS) growth, metastasis, and chemoresistance, we generated stably transfected human STS cell lines with VEGF(165) to study the effect of VEGF(165) on STS cells in vitro and the effect of culture medium from these cells on human umbilical vascular endothelial cells. Severe combined immunodeficient mice bearing xenografts of transfected cell lines were used to assess the effect of VEGF overexpression and the effect of VEGF receptor (VEGFR) 2 inhibition on STS growth, metastasis, and response to doxorubicin. VEGF(165)-transfected xenografts formed highly vascular tumors with shorter latency, accelerated growth, enhanced chemoresistance, and increased incidence of pulmonary metastases. Blockade of VEGFR2 signaling using DC101 anti-VEGFR2 monoclonal antibody enhanced doxorubicin chemoresponse; this combined biochemotherapy inhibited tumor growth and decreased pulmonary metastases without overt toxicity. Combined therapy reduced microvessel counts while increasing vessel maturation index. VEGF overexpression did not affect on the sarcoma cells per se; however, conditioned medium from VEGF transfectants caused increased endothelial cell proliferation, migration, and chemoresistance. Addition of DC101 induced endothelial cell sensitivity to doxorubicin and suppressed the activity of matrix metalloproteinases secreted by endothelial cells. We therefore conclude that VEGF is a critical determinant of STS growth and metastasis and that STS chemoresistance, in our model, is a process induced by the interplay between STS cells and tumor-associated endothelial cells. STS growth and metastasis can be interrupted by combined low-dose doxorubicin and anti-VEGFR2, a strategy that attacks STS-associated endothelial cells. In the future, such therapeutic approaches may be useful in treating STS before the development of clinically apparent metastases.

Antitumor and antivascular effects of AVE8062 in ovarian carcinoma

The purpose of this study was to examine the therapeutic efficacy and underlying mechanisms of action of a vascular-disrupting agent, AVE8062, and to determine its effects on tumor metabolic activity. The in vitro and in vivo effects of AVE8062 alone and in combination with docetaxel were tested in chemotherapy-sensitive and chemotherapy-resistant ovarian cancer models. Tumors were analyzed for necrosis, microvessel density, endothelial cell apoptosis, and proliferation following treatment. The effect of AVE8062 on tumor regression and metabolic activity was examined by magnetic resonance (MR) or by [18F]fluorodeoxyglucose ([18F]FDG) uptake by positron emission tomography (PET) with MR imaging, respectively. AVE8062 monotherapy was effective in inhibiting tumor growth in all models (range 43-51% versus control; P < 0.05). Combination therapy was even more effective in inhibiting tumor growth (range 76-90% compared with controls, P < 0.01). AVE8062 in combination with chemotherapy significantly prolonged survival in HeyA8-injected mice (P < 0.001) compared with other groups. AVE8062-based therapy resulted in rapid development of central tumor necrosis, decreased microvessel density, decreased proliferation, and induction of apoptosis of tumor-associated endothelial cells. MR imaging showed regression of established HeyA8 ovarian tumors and [18F]FDG PET with MR showed rapid decrease in metabolic activity after AVE8062 therapy. Combination of AVE8062 plus docetaxel results in potent inhibition of ovarian cancer growth. These results suggest that AVE8062 may be useful as a clinical therapeutic approach for ovarian cancer patients and that functional [18F]FDG PET imaging may predict clinical response before an anatomic reduction in tumor size.

Inhibition of heat shock protein 90 impairs epidermal growth factor-mediated signaling in gastric cancer cells and reduces tumor growth and vascularization in vivo

Oncogenic signaling through activation of epidermal growth factor receptor (EGFR), HER-2, and hypoxia inducible-factor-1alpha (HIF-1alpha) has been implicated in gastric cancer growth and angiogenesis through up-regulation of vascular endothelial growth factor (VEGF). Recently, heat shock protein 90 (Hsp90) has been identified as a critical regulator of oncogenic protein stability, including EGFR, HER-2, and HIF-1alpha. We hypothesized that inhibition of Hsp90 impairs EGF- and hypoxia-mediated angiogenic signaling in gastric cancer cells and consequently inhibits angiogenesis and tumor growth. In vitro, the geldanamycin derivate 17-allylamino-17-demethoxygeldanamycin (17-AAG) led to marked reduction in constitutive and inducible activation of extracellular signal-regulated kinase 1/2, Akt, and signal transducer and activator of transcription 3 and decreased nuclear HIF-1alpha protein. In addition, EGFR and HER-2 were down-regulated after Hsp90 inhibition. With respect to regulation of angiogenic molecules, 17-AAG significantly reduced EGF-mediated VEGF secretion. Phosphorylation of focal adhesion kinase and paxillin were both abrogated by 17-AAG, which resulted in significant impairment of cancer cell motility. Interestingly, cytotoxic effects of 17-AAG in vitro were higher on cancer cells and gastric fibroblasts than on pericytes. In vivo, the water-soluble compound 17-dimethylaminoethylamino-17-demethoxygeldanamycin (17-DMAG; 25 mg/kg, thrice per week) significantly reduced s.c. xenografted tumor growth. By immunohistochemistry, 17-DMAG significantly reduced vessel area and numbers of proliferating tumor cells in sections. Furthermore, similar significant growth-inhibitory effects of 17-DMAG were achieved when administered as low-dose therapy (5 mg/kg, thrice per week). In conclusion, blocking Hsp90 disrupts multiple proangiogenic signaling pathways in gastric cancer cells and inhibits xenografted tumor growth in vivo. Hence, gastric cancer harbors attractive molecular targets for therapy with Hsp90 inhibitors, which could lead to improved efficacy of antineoplastic therapy regimens.

Role of receptor tyrosine kinases in gastric cancer: New targets for a selective therapy

Receptor tyrosine kinases (RTKs) such as the epidermal growth factor receptor family participate in several steps of tumor formation including proliferation and metastatic spread. Several known RTKs are upregulated in gastric cancer being prime targets of a tailored therapy. Only preliminary data exist, however, on the use of the currently clinically available drugs such as trastuzumab, cetuximab, bevacizumab, gefitinib, erlotinib, and imatinib in the setting of gastric cancer. Preclinical data suggest a potential benefit of their use, especially in combination with “conventional” cytostatic therapy. This review summarizes the current knowledge about their use in cancer therapy as well as new approaches and drugs to optimize treatment success.

Simultaneous inhibition of EGFR, VEGFR, and platelet-derived growth factor receptor signaling combined with gemcitabine produces therapy of human pancreatic carcinoma and prolongs survival in an orthotopic nude mouse model

Although gemcitabine has been approved as the first-line chemotherapeutic reagent for pancreatic cancer, its response rate is low and average survival duration is still only marginal. Because epidermal growth factor receptor (EGFR), vascular endothelial growth factor receptor (VEGFR), and platelet-derived growth factor receptor (PDGFR) modulate tumor progression, we hypothesized that inhibition of phosphorylation of all three on tumor cells, tumor-associated endothelial cells, and stroma cells would improve the treatment efficacy of gemcitabine in an orthotopic pancreatic tumor model in nude mice and prolong survival. We implanted L3.6pl, a human pancreatic cancer cell, in the pancreas of nude mice. We found that tumor-associated endothelial cells in this model highly expressed phosphorylated EGFR, VEGFR, and PDGFR. Oral administration of AEE788, a dual tyrosine kinase inhibitor against EGFR and VEGFR, decreased phosphorylation of EGFR and VEGFR. PDGFR phosphorylation was inhibited by STI571. Although i.p. injection of gemcitabine did not inhibit tumor growth, its combination with AEE788 and STI571 produced >80% inhibition of tumor growth and prolonged survival in parallel with increases in number of tumor cells and tumor-associated endothelial cell apoptosis, decreased microvascular density, decreased proliferation rate, and prolonged survival. STI571 treatment also decreased pericyte coverage on tumor-associated endothelial cells. Thus, inhibiting phosphorylation of EGFR, VEGFR, and PDGFR in combination with gemcitabine enhanced the efficacy of gemcitabine, resulting in inhibition of experimental human pancreatic cancer growth and significant prolongation of survival.

Targeting of urokinase plasminogen activator receptor in human pancreatic carcinoma cells inhibits c-Met- and insulin-like growth factor-I receptor-mediated migration and invasion and orthotopic tumor growth in mice

Pancreatic carcinomas express high levels of urokinase-type plasminogen activator (uPA) and its receptor (uPAR), both of which mediate cell migration and invasion. We investigated the hypotheses that (a) insulin-like growth factor-I (IGF-I)- and hepatocyte growth factor (HGF)-mediated migration and invasion of human pancreatic carcinoma cells require uPA and uPAR function and (b) inhibition of uPAR inhibits tumor growth, retroperitoneal invasion, and hepatic metastasis of human pancreatic carcinomas in mice. Using transwell assays, we investigated the effect of IGF-I and HGF on L3.6pl migration and invasion. We measured the induction of uPA and uPAR following treatment of cells with IGF-I and HGF using immunoprecipitation and Western blot analysis. The importance of uPA and uPAR on L3.6pl cell migration and invasion was studied by inhibiting their activities with amiloride and antibodies before cytokine treatment. In an orthotopic mouse model of human pancreatic carcinoma, we evaluated the effect of anti-uPAR monoclonal antibodies with and without gemcitabine on primary tumor growth, retroperitoneal invasion, and hepatic metastasis. IGF-I and HGF mediated cell migration and invasion in L3.6pl cells. In addition, IGF-I and HGF induced uPA and uPAR expression in L3.6pl cells. In vitro, blockade of uPA and uPAR activity inhibited IGF-I- and HGF-mediated cell migration and invasion. Treatment of mice with anti-uPAR monoclonal antibody significantly decreased pancreatic tumor growth and hepatic metastasis and completely inhibited retroperitoneal invasion. Our study shows the importance of the uPA/uPAR system in pancreatic carcinoma cell migration and invasion. These findings suggest that uPAR is a potential target for therapy in patients with pancreatic cancer.

Dual inhibition of epidermal growth factor receptor and vascular endothelial growth factor receptor phosphorylation by AEE788 reduces growth and metastasis of human colon carcinoma in an orthotopic nude mouse model

We studied growth factors and their receptors in tumor cells and tumor-associated endothelial cells as the therapeutic targets in colon cancer. Immunohistochemical analysis of 13 surgical specimens of human colon adenocarcinoma revealed that both tumor cells and tumor-associated endothelial cells in 11 of the 13 specimens expressed the epidermal growth factor (EGF), transforming growth factor alpha (TGF-alpha), EGF receptor (EGFR), phosphorylated EGFR (pEGFR), vascular endothelial growth factor (VEGF), VEGF receptor (VEGFR), and phosphorylated VEGFR (pVEGFR). HT29 human colon cancer cells growing orthotopically in the cecum of nude mice expressed a high level of EGF, EGFR, pEGFR, VEGF, VEGFR, and pVEGFR. Double-immunofluorescence staining found that tumor-associated mouse endothelial cells also expressed pEGFR and pVEGFR. Tumors in mice treated for 5 weeks with oral AEE788 (an inhibitor of EGFR and VEGFR tyrosine kinase) as a single agent or with CPT-11 alone were smaller (>50%) than those in control mice. Mice treated with the combination of AEE788 and CPT-11 had significantly smaller tumors (P < 0.01) and complete inhibition of lymph node metastasis. AEE788 alone or in combination with CPT-11 inhibited pEGFR, pVEGFR, and phosphorylated Akt expression on tumor-associated endothelial cells as well as on tumor cells. The combination therapy also significantly decreased microvessel density and tumor cell proliferation and increased the level of apoptosis in both tumor cells and tumor-associated endothelial cells. Collectively, these data suggest that the dual inhibition of EGFR and VEGFR signaling pathways in tumor cells and tumor-associated endothelial cells in combination with chemotherapy can provide a new approach to the treatment of colon cancer.

ZD6474 suppresses oncogenic RET isoforms in a Drosophila model for type 2 multiple endocrine neoplasia syndromes and papillary thyroid carcinoma

Patients with hereditary medullary thyroid carcinoma (MTC) associated with multiple endocrine neoplasia (MEN) types 2A and 2B and familial MTC (FMTC) have mutations in the RET proto-oncogene. Approximately 40 percent of patients with papillary thyroid carcinoma (PTC) typically have either intrachromosomal or extrachromosomal rearrangements that join the promoter and NH(2)-terminal domains of unrelated genes to the COOH-terminal fragment of RET. The RET point mutations associated with MEN2A, MEN2B, or FMTC, or the chromosomal breakpoints and translocations associated with PTC, typically activate the RET receptor tyrosine kinase (RTK). RET kinase inhibitors are likely to be beneficial for patients with hereditary MTC, where currently there is no effective chemotherapy or radiation therapy. Recently, the low molecular weight tyrosine kinase inhibitor ZD6474 was found to block the enzymatic activity of RET-derived oncoproteins in cultured cell lines. We have developed a Drosophila model for MEN2A and MEN2B diseases by targeting oncogenic forms of RET to the developing Drosophila eye. Here we show that, when fed orally, ZD6474 suppressed RET-mediated phenotypes within the context of this in vivo model. Importantly, ZD6474 showed high efficacy and very low toxicity. This compound failed to significantly suppress an activated form of another RTK, the Drosophila epidermal growth factor receptor, nor did it suppress the activity of downstream components of the RET/Ras pathway. Our results support the view that targeting chemical kinase inhibitors such as ZD6474 to tissues with oncogenic forms of RET is a useful treatment strategy for RET-dependent carcinomas.