Suppressors for Human Epidermal Growth Factor Receptor 2/4 (HER2/4): A New Family of Anti-Toxoplasmic Agents in ARPE-19 Cells.

The effects of tyrosine kinase inhibitors (TKIs) were evaluated on growth inhibition of intracellular Toxoplasma gondii in host ARPE-19 cells. The number of tachyzoites per parasitophorous vacuolar membrane (PVM) was counted after treatment with TKIs. T. gondii protein expression was assessed by western blot. Immunofluorescence assay was performed using Programmed Cell Death 4 (PDCD4) and T. gondii GRA3 antibodies. The TKIs were divided into 3 groups; non-epidermal growth factor receptor (non-EGFR), anti-human EGFR 2 (anti-HER2), and anti-HER2/4 TKIs, respectively. Group I TKIs (nintedanib, AZD9291, and sunitinib) were unable to inhibit proliferation without destroying host cells. Group II TKIs (lapatinib, gefitinib, erlotinib, and AG1478) inhibited proliferation up to 98% equivalent to control pyrimethamine (5 µM) at 20 µM and higher, without affecting host cells. Group III TKIs (neratinib, dacomitinib, afatinib, and pelitinib) inhibited proliferation up to 98% equivalent to pyrimethamine at 1-5 µM, but host cells were destroyed at 10-20 µM. In Group I, TgHSP90 and SAG1 inhibitions were weak, and GRA3 expression was moderately inhibited. In Group II, TgHSP90 and SAG1 expressions seemed to be slightly enhanced, while GRA3 showed none to mild inhibition; however, AG1478 inhibited all proteins moderately. Protein expression was blocked in Group III, comparable to pyrimethamine. PDCD4 and GRA3 were well localized inside the nuclei in Group I, mildly disrupted in Group II, and were completely disrupted in Group III. This study suggests the possibility of a vital T. gondii TK having potential HER2/4 properties, thus anti-HER2/4 TKIs may inhibit intracellular parasite proliferation with minimal adverse effects on host cells.

The EGFR tyrosine kinase inhibitor tyrphostin AG-1478 causes hypomagnesemia and cardiac dysfunction.

We determined whether the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) N-​(3-​chlorophenyl)-​6,​7-​dimethoxy-​4-​quinazolinamine (tyrphostin AG-1478) causes hypomagnesemia and cardiac dysfunction in rats. Tyrphostin was administered (3 times per week, intraperitoneal injection, to achieve 21.4 mg·(kg body mass)(-1)·day(-1)) to normomagnesemic rats for 5 weeks. Levels of magnesium in the plasma of the tyrphostin-treated rats decreased significantly by the following amount: 17% at week 1, 27% at week 2, and 26%-35% between weeks 3 to 5. Levels of the plasma lipid peroxidation marker 8-isoprostane rose significantly: by 58% at week 1, 168% at week 3, and 113% at week 5. At week 5, blood neutrophils from the tyrphostin-treated group displayed a 2.26-fold higher basal level of O(2)(·-) generation; the ratio of oxidized glutathione (glutathione disulfide; GSSG) to reduced glutathione (GSH) in the red blood cells increased 2.5-fold. At week 5, echocardiography revealed that TKI treatment resulted in significant cardiac systolic dysfunction, with impaired diastolic function and dilated cardiomyopathy. Since hypomagnesemia alone can trigger oxidative stress and cardiac injury, we suggest that inhibition of EGFR-TK caused magnesium wasting, which partly contributed to decreased cardiac contractility.

Cisplatin-resistant neuroblastoma cells express enhanced levels of epidermal growth factor receptor (EGFR) and are sensitive to treatment with EGFR-specific toxins.

PURPOSE: Neuroblastomas frequently show expression of the epidermal growth factor receptor (EGFR) and may therefore be susceptible to EGFR-targeted therapies. Here, EGFR expression and functionality was investigated in parental chemosensitive neuroblastoma cell lines (UKF-NB-3, IMR-32, NLF, SH-SY5Y) and their cisplatin-resistant sublines (UKF-NB-3(r)CDDP(1000), IMR-32(r)CDDP(1000), NLF(r)CDDP(1000), and SH-SY5Y(r)CDDP(500)). Moreover, the EGFR antibody cetuximab, the EGFR tyrosine kinase inhibitor Tyrphostin B46, and recombinant EGFR-targeted toxins were investigated for their influence on the viability and growth of neuroblastoma cells. EXPERIMENTAL DESIGN: EGFR expression and function was measured by flow cytometry or Western blot. Cell viability was detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Apoptosis was examined by immunostaining for active caspase-3 or cleaved poly(ADP-ribose) polymerase. Cellular binding of FITC-labeled immunotoxins was studied by flow cytometry, and cellular uptake was studied by confocal laser scanning microscopy. RESULTS: The EGFR-targeted antibody and growth factor toxins scFv(14E1)- Pseudomonas exotoxin A (ETA) and TGF-alpha-ETA exerted anti-cancer effects in neuroblastoma cell lines that were insensitive to cetuximab or EGFR tyrosine kinase inhibitors. Furthermore, adaptation of chemosensitive neuroblastoma cells to cisplatin increased EGFR expression and sensitivity to both recombinant toxins. Treatment of chemosensitive neuroblastoma cells with cisplatin reversibly increased EGFR expression, whereas cisplatin-resistant cells showed enhanced EGFR expression independent of the presence of cisplatin. Combination treatment with scFv(14E1)-ETA or TGF-alpha-ETA and cisplatin exerted significantly improved anticancer effects compared with either single treatment in parental neuroblastoma cells, cisplatin-resistant sublines, and primary cultures. CONCLUSIONS: EGFR-targeted cytotoxic reagents such as scFv(14E1)-ETA and TGF-alpha-ETA represent promising candidates for further development as antineuroblastoma agents, especially in combination with cisplatin.

ADAM17 and EGFR regulate IL-6 receptor and amphiregulin mRNA expression and release in cigarette smoke-exposed primary bronchial epithelial cells from patients with chronic obstructive pulmonary disease (COPD).

Aberrant activity of a disintegrin and metalloprotease 17 (ADAM17), also known as TACE, and epidermal growth factor receptor (EGFR) has been suggested to contribute to chronic obstructive pulmonary disease (COPD) development and progression. The aim of this study was to investigate the role of these proteins in activation of primary bronchial epithelial cells differentiated at the air-liquid interface (ALI-PBEC) by whole cigarette smoke (CS), comparing cells from COPD patients with non-COPD CS exposure of ALI-PBEC enhanced ADAM17-mediated shedding of the IL-6 receptor (IL6R) and the EGFR agonist amphiregulin (AREG) toward the basolateral compartment, which was more pronounced in cells from COPD patients than in non-COPD controls. CS transiently increased IL6R and AREG mRNA in ALI-PBEC to a similar extent in cultures from both groups, suggesting that posttranslational events determine differential shedding between COPD and non-COPD cultures. We show for the first time by in situ proximity ligation (PLA) that CS strongly enhances interactions of phosphorylated ADAM17 with AREG and IL-6R in an intracellular compartment, suggesting that CS-induced intracellular trafficking events precede shedding to the extracellular compartment. Both EGFR and ADAM17 activity contribute to CS-induced IL-6R and AREG protein shedding and to mRNA expression, as demonstrated using selective inhibitors (AG1478 and TMI-2). Our data are consistent with an autocrine-positive feedback mechanism in which CS triggers shedding of EGFR agonists evoking EGFR activation, in ADAM17-dependent manner, and subsequently transduce paracrine signaling toward myeloid cells and connective tissue. Reducing ADAM17 and EGFR activity could therefore be a therapeutic approach for the tissue remodeling and inflammation observed in COPD.

Synthesis, 11C labeling and biological properties of derivatives of the tyrphostin AG957.

Four analogues of AG957, a known inhibitor of the tyrosine kinase p210(bcr-abl), have been synthesized and tested for their growth inhibitory effect against the BCR/ABL-positive FDrv210C cells as well as the epidermal growth factor (EGF) receptor-positive Baf/ERX cells. All compounds that can undergo oxidation to the corresponding quinone demonstrated inhibition of FDrv210C cells and Baf/ERX cells. Compounds that cannot become oxidized showed significantly less inhibition of BCR/ABL- or EGF receptor-mediated cell proliferation. The (11)C-labeled compounds were prepared by labeling 4-aminobenzoic acid using [(11)C]CH(3)I, which afforded the corresponding (11)C-labeled methyl ester in excellent yields. Subsequent condensation of the amino group with an appropriately substituted hydroxy benzaldehyde formed the respective Schiff base. Reduction of this compound with NaBH(3)CN gave the (11)C-labeled inhibitors in an overall radiochemical yield of 17.3+/-2.1% (n=3; not decay corrected) and an average specific radioactivity of 40 GBq/micromol (1.1 Ci/micromol) at the end of synthesis. The total synthesis time from EOB including HPLC purification and formulation was 45 min.

Epidermal growth factor receptor tyrosine kinase inhibition up-regulates interleukin-6 in cancer cells and induces subsequent development of interstitial pneumonia.

Acute interstitial pneumonia is one of serious side effects of epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI) treatment, while it often has significant clinical benefit in cancer patients. Therefore, it is necessary to clarify underlying mechanisms for the development of the adverse effects by EGFR-TKI. In the present study, we attempted to determine how EGFR-TKI treatment in cancer cells induced interstitial pneumonia. The growth of tongue cancer HSC-3 and lung cancer A549 cell lines treated with EGFR-TKI was assessed by MTT assay. Cytokines and growth factors in conditioned medium (CM) obtained from EGFR-TKI-treated cancer cells were analyzed using cytokine membrane array and ELISA. Interleukin-6 (IL-6) promoter activity was measured by luciferase assay. We found that EGFR-TKI treatment significantly decreased the cell viability yet increased expression levels of IL-6 protein and mRNA, IL-6 secretion, and IL-6 transcriptional activity in these lines. In addition, using the co-culture model and IL-6 treatment was found to increase the expression of collagen and α-actin, which were markers for fibrosis, in lung fibroblast cells. These results suggest that up-regulated IL-6 plays an important role in the development of EGFR-TKI-induced interstitial fibroblastic proliferation. Therefore, blocking of IL-6 signaling could be beneficial to cancer patients undergoing EGFR-TKI treatment for reducing the risk of its unfavorable effects.

The putative JAK-STAT inhibitor AG490 exacerbates LPS-fever, reduces sickness behavior, and alters the expression of pro- and anti-inflammatory genes in the rat brain.

The functional significance for activation of inflammatory transcription factors, such as signal transducer and activator of transcription (STAT3), nuclear factor (NF)κB or NF-interleukin (IL)6 and their contribution to the induction of brain controlled sickness responses, such as fever, during infection and inflammation is unknown. Using AG490, previously shown to inhibit the STAT3- and NF-IL6-signaling pathway, we therefore investigated the central involvement of these two signaling pathways in mediating sickness behavior, fever and accompanying brain inflammation induced by peripheral lipopolysaccharide (LPS)-stimulation. Rats pre-treated i.c.v. with AG490 1 h before the i.p. LPS-challenge (100 µg/kg) showed a modestly exaggerated fever, attenuated adipsia and almost unimpaired locomotor activity compared to LPS-controls receiving vehicle (i.c.v.). The LPS-induced anorexia was not altered and AG490 did not have any effect on rats receiving PBS (i.p.). We did observe effects of AG490 on STAT3-signaling at 4 h, while AG490-mediated changes in brain activity of inflammatory transcription factors at 8 h were not significant. Increased NF-IL6 and suppressor of cytokines 3 mRNA-expression in AG490/LPS-treated rats were indicative of a compensative activation at 24 h. Moreover, a significant decrease in hypothalamic anti-inflammatory IL-10-expression and an increase in inflammatory microsomal prostaglandin E synthase (mPGES) mRNA-expression 8 h after LPS-injection was revealed in AG490 pre-treated animals compared to solvent-treated LPS-controls. In summary, we have shown a dissociation between the effects of central AG490 treatment on fever and components of sickness behavior, which appears to be related to reduced IL-10 and increased mPGES-expression in the brain. Thus, AG490 might have therapeutic potential to reduce sickness behavior.

Tyrphostin-8 enhances transferrin receptor-mediated transcytosis in Caco-2- cells and inreases hypoglycemic effect of orally administered insulin-transferrin conjugate in diabetic rats.

PURPOSE: To investigate the effect of tyrphostin 8 (T-8), a GTPase inhibitor, on transferrin receptor (TfR)-mediated transcytosis of insulin-transferrin (In-Tf) conjugate in cultured enterocyte-like Caco-2 cells and on gastrointestinal (GI) absorption of In-Tf in streptozotocin (STZ)-induced diabetic rats. METHODS: Caco-2 cells and diabetic rats were used as in vitro and in vivo models, respectively. TfR-mediated transcytosis was measured using 125I-In-Tf. The absorption of insulin in diabetic rats was demonstrated by the hypoglycemic effect. Rat blood glucose level was determined using a ONE TOUCH blood glucose monitoring system. RESULTS: T-8 increased apical-to-basolateral transport of In-Tf conjugate by enhancing TfR-mediated transcytosis in filter-grown Caco-2 cell monolayer, and this enhancement was higher and faster than the previously reported brefeldin A (BFA)-induced effect. The measurement of transepithelial electrical resistance (TEER) during the transport study showed that T-8 was less destructive on the cell tight junction than BFA. The GI absorption of In-Tf was evaluated by its hypoglycemic effect after oral administration in STZ-induced diabetic rats. The glucose-lowering effect of orally administered In-Tf in STZ-induced diabetic rats was improved by either T-8 or BFA. However, the effect of T-8 was more potent than that of BFA, especially at 7 h after administration. Either non-conjugated insulin or insulin-human serum albumin (In-HSA) conjugate by itself or in combination with T-8 did not show any hypoglycemic effect after oral administration, indicating that T-8-enhanced hypoglycemic activity of In-Tf was due to a selective enhancement of TfR-mediated transcytosis. CONCLUSIONS: Our data indicated that T-8 could be used to increase the GI absorption of insulin as a transferrin conjugate. T-8, as an enhancer of TfR-mediated transcytosis, is better than the previously reported BFA. T-8 produces a higher increase on the transport of In-Tf and a lower toxicity on epithelial cells. Our findings provide an alternative approach to promote the GI absorption of insulin, as well as other peptide or protein drugs.