JTE-607, a cytokine release blocker, attenuates acid aspiration-induced lung injury in rats

The anticancer compound JTE-607 reveals hidden sequence specificity of the mRNA 3' processing machinery

JTE-607 is an anticancer and anti-inflammatory compound and its active form, compound 2, directly binds to and inhibits CPSF73, the endonuclease for the cleavage step in pre-messenger RNA (pre-mRNA) 3' processing. Surprisingly, compound 2-mediated inhibition of pre-mRNA cleavage is sequence specific and the drug sensitivity is predominantly determined by sequences flanking the cleavage site (CS). Using massively parallel in vitro assays, we identified key sequence features that determine drug sensitivity. We trained a machine learning model that can predict poly(A) site (PAS) relative sensitivity to compound 2 and provide the molecular basis for understanding the impact of JTE-607 on PAS selection and transcription termination genome wide. We propose that CPSF73 and associated factors bind to the CS region in a sequence-dependent manner and the interaction affinity determines compound 2 sensitivity. These results have not only elucidated the mechanism of action of JTE-607, but also unveiled an evolutionarily conserved sequence specificity of the mRNA 3' processing machinery.

The anti-cancer compound JTE-607 reveals hidden sequence specificity of the mRNA 3' processing machinery

JTE-607 is a small molecule compound with anti-inflammation and anti-cancer activities. Upon entering the cell, it is hydrolyzed to Compound 2, which directly binds to and inhibits CPSF73, the endonuclease for the cleavage step in pre-mRNA 3' processing. Although CPSF73 is universally required for mRNA 3' end formation, we have unexpectedly found that Compound 2- mediated inhibition of pre-mRNA 3' processing is sequence-specific and that the sequences flanking the cleavage site (CS) are a major determinant for drug sensitivity. By using massively parallel in vitro assays, we have measured the Compound 2 sensitivities of over 260,000 sequence variants and identified key sequence features that determine drug sensitivity. A machine learning model trained on these data can predict the impact of JTE-607 on poly(A) site (PAS) selection and transcription termination genome-wide. We propose a biochemical model in which CPSF73 and other mRNA 3' processing factors bind to RNA of the CS region in a sequence-specific manner and the affinity of such interaction determines the Compound 2 sensitivity of a PAS. As the Compound 2-resistant CS sequences, characterized by U/A-rich motifs, are prevalent in PASs from yeast to human, the CS region sequence may have more fundamental functions beyond determining drug resistance. Together, our study not only characterized the mechanism of action of a compound with clinical implications, but also revealed a previously unknown and evolutionarily conserved sequence-specificity of the mRNA 3' processing machinery.

CPSF3-dependent pre-mRNA processing as a druggable node in AML and Ewing's sarcoma

The post-genomic era has seen many advances in our understanding of cancer pathways, yet resistance and tumor heterogeneity necessitate multiple approaches to target even monogenic tumors. Here, we combine phenotypic screening with chemical genetics to identify pre-messenger RNA endonuclease cleavage and polyadenylation specificity factor 3 (CPSF3) as the target of JTE-607, a small molecule with previously unknown target. We show that CPSF3 represents a synthetic lethal node in a subset of acute myeloid leukemia (AML) and Ewing's sarcoma cancer cell lines. Inhibition of CPSF3 by JTE-607 alters expression of known downstream effectors in AML and Ewing's sarcoma lines, upregulates apoptosis and causes tumor-selective stasis in mouse xenografts. Mechanistically, it prevents the release of newly synthesized pre-mRNAs, resulting in read-through transcription and the formation of DNA-RNA hybrid R-loop structures. This study implicates pre-mRNA processing, and specifically CPSF3, as a druggable target providing an avenue to therapeutic intervention in cancer.

JTE-607, a multiple cytokine production inhibitor, targets CPSF3 and inhibits pre-mRNA processing

JTE-607 is a small molecule that was developed as an inflammatory cytokine inhibitor and also as an anti-leukemia reagent for monocytic leukemia. However, the mode of action of JTE-607 remains unknown. In this study, we identified JTE-607 to be a prodrug compound that is converted to an active form by ester hydrolysis. Furthermore, we determined that the active form of JTE-607 bound cleavage and polyadenylation specificity factor subunit 3 (CPSF3), using compound-immobilized affinity chromatography. CPSF3 is a 73-kDa subunit of the cleavage and polyadenylation specificity factor complex, which functions as an RNA endonuclease. The protein is involved in the 3'-end processing of messenger RNA precursors (pre-mRNAs) at the cleavage site located downstream of the poly(A) addition signal. We found that treatment with JTE-607 caused accumulation of pre-mRNAs. Furthermore, knockdown experiments showed that CPSF3 deficiency also caused accumulation of pre-mRNAs and suppressed the expression of inflammatory cytokines, like JTE-607. These findings indicated that CPSF3 is a direct target of JTE-607 and a new potential target for the treatment of disease-related abnormal cytokine production.

Causative treatment of acid aspiration induced acute lung injury - Recent trends from animal experiments and critical perspective

Aspiration of low-pH gastric fluid leads to an initial pneumonitis, which may become complicated by subsequent pneumonia or acute respiratory distress syndrome. Current treatment is at best supportive, but there is growing experimental evidence on the significant contribution of both neutrophils and platelets in the development of this inflammatory pulmonary reaction, a condition that can be attenuated by several medicinal products. This review aims to summarize novel findings in experimental models on pathomechanisms after an acid-aspiration event. Given the clinical relevance, specific emphasis is put on deduced potential experimental therapeutic approaches, which make use of the characteristic alteration of microcirculation in the injured lung.

Exogenous surfactant instillation attenuates inflammatory response to acid-induced lung injury in rat

The present study was performed to investigate the role of exogenous surfactant on hydrochloric acid (HCL) - induced lung injury in rats. Six-week-old male Sprague-Dawley rats were anesthetized by intraperitoneal injection of pentobarbital sodium (40mg/kg) and HCL (0.1N, 2mL/kg) or normal saline (NS, 2mL/kg) was instilled into the trachea. Thirty minutes after HCL instillation, surfactant at a dose of 60mg (=2mL)/body or NS (2mL) was instilled into the rat lungs. Animals in another experimental group were also treated with the same dose of surfactant supplement 2hours after the first administration. Bronchoalveolar lavage fluid (BALF) was obtained 5hours after HCL instillation. In BALF, increases in total nuclear cell counts, neutrophil counts, optical density at 412nm as an indicator of pulmonary hemorrhage, neutrophil elastase activity, concentrations of albumin and cytokine-induced neutrophil chemoattractant (CINC) induced by HCL instillation were significantly attenuated by surfactant treatment. The wet-to-dry weight (W/D) ratio in the lung and partial oxygen tension (P(O2)) were also estimated; surfactant treatment significantly attenuated the W/D ratio and improved deteriorated P(O2) induced by HCL. Additional surfactant supplementation did not show further beneficial effects on HCL-induced lung injury compared with a single treatment. These results suggest that surfactant shows an anti-inflammatory effect on acid lung injury in rats but the beneficial effects may be dose limited.

Preventive effects of curcumin on different aspiration material-induced lung injury in rats

PURPOSE

We have studied whether curcumin protects different pulmonary aspiration material-induced lung injury in rats.

MATERIALS AND METHODS

The experiments were designed in 60 Sprague-Dawley rats, randomly allotted into one of six groups (n=10): normal saline (NS, control), enteral formula (Biosorb Energy Plus, BIO), hydrochloric acid (HCl), NS+curcumin-treated, BIO+curcumin-treated, and HCl+curcumin-treated. NS, BIO, HCl were injected in to the lungs. The rats received curcumin twice daily only for 7 days. Seven days later, both lungs in all groups were examined histopathologically, immunohistochemically, and biochemically. Histopathologic examination was performed according to the presence of peribronchial inflammatory cell infiltration, alveolar septal infiltration, alveolar edema, alveolar exudate, alveolar histiocytes, interstitial fibrosis, granuloma, and necrosis formation. Immunohistochemical assessments were examined for the activity of inducible nitric oxide synthase (iNOS) and the expression of surfactant protein D (SP-D). Malondialdehyde (MDA), hydroxyproline (HP), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) activity were measured in the lung tissue.

RESULTS

Our findings show that curcumin inhibits the inflammatory response reducing significantly (P<0.05) all histopathological parameters in different pulmonary aspiration models. Pulmonary aspiration significantly increased the tissue HP content, MDA levels and decreased the antioxidant enzyme (SOD, GSH-Px) activities. Curcumin treatment significantly decreased the elevated tissue HP content, and MDA levels and prevented inhibition of SOD, and GSH-Px enzymes in the tissues. Furthermore, our data suggest that there is a significant reduction in the activity of iNOS and a rise in the expression of SP-D in lung tissue of different pulmonary aspiration models with curcumin therapy.

CONCLUSION

Our findings support the use of curcumin as a potential therapeutic agent in acute lung injury.

Protective effects of S-methylisothiourea sulfate on different aspiration materials-induced lung injury in rats

OBJECTIVES

The aim of this study was to evaluate the efficiency of inducible nitric oxide synthase (iNOS) specific inhibitor, S-methylisothiourea sulfate (SMT) in preventing lung injury after different pulmonary aspiration materials in rats.

MATERIAL AND METHODS

The experiments were performed in 80 Sprague-Dawley rats, ranging in weight from 220 to 250 g, randomly allotted into one of the eight groups (n=10): normal saline (NS, control), Biosorb Energy Plus (BIO), sucralfate (SUC), hydrochloric acid (HCl), NS+SMT treated, BIO+SMT treated, SUC+SMT treated, and HCl+SMT treated. NS, BIO, SUC, HCl were injected in to the lungs in a volume of 2 ml/kg. The rats received twice daily intraperitoneal injections of 20 mg(kg day) SMT (Sigma Chemical Co.) for 7 days. Seven days later, rats were killed, and both lungs in all groups were examined immunohistochemically and histopathologically.

RESULTS

Our data show that SMT inhibits the inflammatory response significantly reducing (p<0.05) peribronchial inflammatory cell infiltration, alveolar septal infiltration, alveolar edema, alveolar exudate, alveolar histiocytes, interstitial fibrosis, granuloma, and necrosis formation in different pulmonary aspiration models. Furthermore, our data suggest that there is a significant reduction in the activity of iNOS and arise in the expression of surfactant protein D in lung tissue of different pulmonary aspiration models with SMT therapy.

CONCLUSION

It was concluded that SMT treatment might be beneficial in lung injury, therefore shows potential for clinical use.

Activated protein C attenuates acid-aspiration lung injury in rats

Acid aspiration causes direct lung damage and secondary inflammatory response involving several cytokines and accumulation of neutrophils. Activated protein C (APC) exhibits antithrombotic and anti-inflammatory properties. We examined the effect and mechanism of pre-treatment APC on acid-aspirated lung injury in rats. Anesthetized rats were instilled intratracheally with normal saline (NS, 2 ml kg(-1)) or hydrochloric acid (HCl, 0.1 N, 2 ml kg(-1)). Thirty minutes before HCl instillation, APC (200 U kg(-1) h(-1)) was infused continuously into the right jugular vein. Animals were ventilated during the experiments. Five hours after HCl or NS instillation, bronchoalveolar lavage fluid (BALF) and lung tissue samples were obtained. Total and differential cell count, absorbance, albumin concentration, concentrations of tumor necrosis factor (TNF)-alpha, interleukin (IL)-6 and cytokine-induced neutrophil chemoattractant (CINC) in BALF, wet and dry weight (W/D) ratio were measured. Platelet count and fibrin degradation product (FDP) in peripheral blood were also measured. HCl instillation markedly increased these values in BALF as well as W/D ratio. APC attenuated the parameters increased by HCl-induced lung injury in rats. However, HCl instillation and APC treatment did not cause significant changes in platelet count and FDP compared with the control. We conclude that APC treatment protected the rats against HCl-induced lung injury and that this action seemed to be due to the anti-inflammatory properties of this protein rather than its anti-coagulant effects.

Effects of Granulocyte Colony-Stimulating Factor (G-CSF) and Neutrophil Elastase Inhibitor (ONO-5046) on Acid-Induced Lung Injury in Rats

It has been suggested that neutrophils play an important role in acid-aspirated lung injury. We examined the effects of the high dose of granulocyte-colony stimulating factor (G-CSF), which is capable of increasing peripheral neutrophils, and a specific neutrophil elastase inhibitor (ONO-5046) on acid lung injury in rats. Animals were anesthetized and normal saline (NS, 2 mL kg(-1)) or hydrochloric acid (HCl, 0.1 N 2 mL kg(-1)) was then instilled into trachea. Thirty minutes before HCl instillation, G-CSF (150 microg kg(-1)) was injected subcutaneously or ONO-5046 (10 mg kg(-1) h(-1)) was infused continuously into the right jugular vein. Animals were ventilated during the experiments. Five hours after HCl or NS instillation, bronchoalveolar lavage fluid (BALF) and lung tissue samples were obtained. Total nuclear cell count, absorbance, albumin, tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, cytokine-induced neutrophil chemoattractant (CINC), neutrophil elastase in BALF, wet-to-dry (W/D) ratio were measured. HCl aspiration markedly increased these values in BALF and W/D ratio. Both ONO-5046 and G-CSF attenuated the parameters increased by acid-induced lung injury in rats. The data suggests that neutrophils play an important role in acid-induced lung injury. However, high-dose G-CSF does not exacerbate acid-aspirated lung injury in rats, although this agent causes an increase in peripheral neutrophils.