Hypoxia induces downregulation of the tumor-suppressive sST2 in colorectal cancer cells via the HIF-nuclear IL-33-GATA3 pathway.

As a decoy receptor, soluble ST2 (sST2) interferes with the function of the inflammatory cytokine interleukin (IL)-33. Decreased sST2 expression in colorectal cancer (CRC) cells promotes tumor growth via IL-33-mediated bioprocesses in the tumor microenvironment. In this study, we discovered that hypoxia reduced sST2 expression in CRC cells and explored the associated molecular mechanisms, including the expression of key regulators of ST2 gene transcription in hypoxic CRC cells. In addition, the effect of the recovery of sST2 expression in hypoxic tumor regions on malignant progression was investigated using mouse CRC cells engineered to express sST2 in response to hypoxia. Our results indicated that hypoxia-dependent increases in nuclear IL-33 interfered with the transactivation activity of GATA3 for ST2 gene transcription. Most importantly, hypoxia-responsive sST2 restoration in hypoxic tumor regions corrected the inflammatory microenvironment and suppressed tumor growth and lung metastasis. These results indicate that strategies targeting sST2 in hypoxic tumor regions could be effective for treating malignant CRC.

A novel LncRNA PTH-AS upregulates interferon-related DNA damage resistance signature genes and promotes metastasis in human breast cancer xenografts.

Long noncoding RNAs (lncRNAs) are important tissue-specific regulators of gene expression, and their dysregulation can induce aberrant gene expression leading to various pathological conditions, including cancer. Although many lncRNAs have been discovered by computational analysis, most of these are as yet unannotated. Herein, we describe the nature and function of a novel lncRNA detected downstream of the human parathyroid hormone (PTH) gene in both extremely rare ectopic PTH-producing retroperitoneal malignant fibrous histiocytoma and parathyroid tumors with PTH overproduction. This novel lncRNA, which we have named "PTH-AS," has never been registered in a public database, and here, we investigated for the first time its exact locus, length, transcription direction, polyadenylation, and nuclear localization. Microarray and Gene Ontology analyses demonstrated that forced expression of PTH-AS in PTH-nonexpressing human breast cancer T47D cells did not induce the ectopic expression of the nearby PTH gene but did significantly upregulate Janus kinase-signal transducer and activator of transcription pathway-related genes such as cancer-promoting interferon-related DNA damage resistance signature (IRDS) genes. Importantly, we show that PTH-AS expression not only enhanced T47D cell invasion and resistance to the DNA-damaging drug doxorubicin but also promoted lung metastasis rather than tumor growth in a mouse xenograft model. In addition, PTH-AS-expressing T47D tumors showed increased macrophage infiltration that promoted angiogenesis, similar to IRDS-associated cancer characteristics. Although the detailed molecular mechanism remains imperfectly understood, we conclude that PTH-AS may contribute to tumor development, possibly through IRDS gene upregulation.

Retrotransposition of long interspersed element 1 induced by methamphetamine or cocaine.

Long interspersed element 1 (L1) is a retroelement constituting ∼17% of the human genome. A single human cell has 80-100 copies of L1 capable of retrotransposition (L1-RTP), ∼10% of which are "hot L1" copies, meaning they are primed for "jumping" within the genome. Recent studies demonstrated induction of L1 activity by drugs of abuse or low molecular weight compounds, but little is known about the underlying mechanism. The aim of this study was to identify the mechanism and effects of methamphetamine (METH) and cocaine on L1-RTP. Our results revealed that METH and cocaine induced L1-RTP in neuronal cell lines. This effect was found to be reverse transcriptase-dependent. However, METH and cocaine did not induce double-strand breaks. RNA interference experiments combined with add-back of siRNA-resistant cDNAs revealed that the induction of L1-RTP by METH or cocaine depends on the activation of cAMP response element-binding protein (CREB). METH or cocaine recruited the L1-encoded open reading frame 1 (ORF1) to chromatin in a CREB-dependent manner. These data suggest that the cellular cascades underlying METH- and cocaine-induced L1-RTP are different from those behind L1-RTP triggered by DNA damage; CREB is involved in drug-induced L1-RTP. L1-RTP caused by drugs of abuse is a novel type of genomic instability, and analysis of this phenomenon might be a novel approach to studying substance-use disorders.

A knock-in mouse model of N-terminal R420W mutation of cardiac ryanodine receptor exhibits arrhythmogenesis with abnormal calcium dynamics in cardiomyocytes.

Cardiac ryanodine receptor gene (RyR2) mutations cause fatal arrhythmogenic diseases such as catecholaminergic polymorphic ventricular tachycardia and arrhythmogenic right ventricular cardiomyopathy. The N-terminal region of RyR2 is one of the hot spots for mutations. In this study, we investigated cardiac phenotypes of a knock-in mouse model carrying R420W mutation of RyR2. The N-terminal R420W mutation has already been found in juvenile sudden death cadavers of unrelated families. The depolarization-induced Ca(2+) transient amplitude was significantly lower in cardiomyocytes from RyR2(R420W/R420W) mice compared with wild-type mice. The time to peak of the Ca(2+) transient was significantly increased in RyR2(R420W/R420W) mice. Furthermore, the prolonged decay time from the peak of the Ca(2+) transient was detected in RyR2(R420W/R420W) mice. ECG telemetry revealed that various types of arrhythmias were induced in RyR2(R420W/R420W) mice in response to administration of caffeine and adrenaline. The mutant mice showed high occurrences of arrhythmias in response to heart stimulants compared with wild-type mice. These findings suggest that R420W mutation impairs depolarization-induced Ca(2+) oscillation in cardiomyocytes, which possibly results in sudden death due to stress-induced arrhythmias.

Accumulation of senescent cells in the adrenal gland induces hypersecretion of corticosterone via IL1ß secretion.

Aging progresses through the interaction of metabolic processes, including changes in the immune and endocrine systems. Glucocorticoids (GCs), which are regulated by the hypothalamic-pituitary-adrenal (HPA) axis, play an important role in regulating metabolism and immune responses. However, the age-related changes in the secretion mechanisms of GCs remain elusive. Here, we found that corticosterone (CORT) secretion follows a circadian rhythm in young mice, whereas it oversecreted throughout the day in aged mice >18 months old, resulting in the disappearance of diurnal variation. Furthermore, senescent cells progressively accumulated in the zF of the adrenal gland as mice aged beyond 18 months. This accumulation was accompanied by an increase in the number of Ad4BP/SF1 (SF1), a key transcription factor, strongly expressing cells (SF1-high positive: HP). Removal of senescent cells with senolytics, dasatinib, and quercetin resulted in the reduction of the number of SF1-HP cells and recovery of CORT diurnal oscillation in 24-month-old mice. Similarly, administration of a neutralizing antibody against IL1ß, which was found to be strongly expressed in the adrenocortical cells of the zF, resulted in a marked decrease in SF1-HP cells and restoration of the CORT circadian rhythm. Our findings suggest that the disappearance of CORT diurnal oscillation is a characteristic of aging individuals and is caused by the secretion of IL1ß, one of the SASPs, from senescent cells that accumulate in the zF of the adrenal cortex. These findings provide a novel insight into aging. Age-related hypersecretory GCs could be a potential therapeutic target for aging-related diseases.

Viral protein R of human immunodeficiency virus type-1 induces retrotransposition of long interspersed element-1.

BACKGROUND: Viral protein R (Vpr), a protein of human immunodeficiency virus type-1 (HIV-1) with various biological functions, was shown to be present in the blood of HIV-1-positive patients. However, it remained unclear whether circulating Vpr in patients' blood is biologically active. Here, we examined the activity of blood Vpr using an assay system by which retrotransposition of long interspersed element-1 (L1-RTP) was detected. We also investigated the in vivo effects of recombinant Vpr (rVpr) by administrating it to transgenic mice harboring human L1 as a transgene (hL1-Tg mice). Based on our data, we discuss the involvement of blood Vpr in the clinical symptoms of acquired immunodeficiency syndrome (AIDS). RESULTS: We first discovered that rVpr was active in induction of L1-RTP. Biochemical analyses revealed that rVpr-induced L1-RTP depended on the aryl hydrocarbon receptor, mitogen-activated protein kinases, and CCAAT/enhancer-binding protein ß. By using a sensitive L1-RTP assay system, we showed that 6 of the 15 blood samples from HIV-1 patients examined were positive for induction of L1-RTP. Of note, the L1-RTP-inducing activity was blocked by a monoclonal antibody specific for Vpr. Moreover, L1-RTP was reproducibly induced in various organs, including the kidney, when rVpr was administered to hL1-Tg mice. CONCLUSIONS: Blood Vpr is biologically active, suggesting that its monitoring is worthwhile for clarification of the roles of Vpr in the pathogenesis of AIDS. This is the first report to demonstrate a soluble factor in patients' blood active for L1-RTP activity, and implies the involvement of L1-RTP in the development of human diseases.

Induction of long interspersed nucleotide element-1 (L1) retrotransposition by 6-formylindolo[3,2-b]carbazole (FICZ), a tryptophan photoproduct.

Long interspersed nucleotide element-1 (L1) is a retroelement comprising about 17% of the human genome, of which 80-100 copies are competent as mobile elements (retrotransposition: L1-RTP). Although the genetic structures modified during L1-RTP have been clarified, little is known about the cellular signaling cascades involved. Herein we found that 6-formylindolo[3,2-b]carbazole (FICZ), a tryptophan photoproduct postulated as a candidate physiological ligand of the aryl hydrocarbon receptor (AhR), induces L1-RTP. Notably, RNA-interference experiments combined with back-transfection of siRNA-resistant cDNAs revealed that the induction of L1-RTP by FICZ is dependent on AhR nuclear translocator-1 (ARNT1), a binding partner of AhR, and the activation of cAMP-responsive element-binding protein. However, our extensive analyses suggested that AhR is not required for L1-RTP. FICZ stimulated the interaction of the L1-encoded open reading frame-1 (ORF1) and ARNT1, and recruited ORF1 to chromatin in a manner dependent on the activation of mitogen-activated protein kinase. Along with our additional observations that the cellular cascades for FICZ-induced L1-RTP were different from those of L1-RTP triggered by DNA damage, we propose that the presence of the cellular machinery of ARNT1 mediates L1-RTP. A possible role of ARNT1-mediated L1-RTP in the adaptation of living organisms to environmental changes is discussed.

Resveratrol blocks retrotransposition of LINE-1 through PPAR α and sirtuin-6.

The retroelement long interspersed element-1 (LINE-1 or L1) comprises about 17% of the human genome. L1 retrotransposition is known to cause genomic instability and related disorders, and resveratrol suppresses this retrotransposition; however, the underlying mechanism is still not elucidated. Recent observations showed that low-molecular-weight compounds might induce L1 retrotransposition through unknown mechanisms. This study aimed to determine polyphenol resveratrol (RV)'s effect on L1-RTP (retrotransposition) in somatic cells. Surprisingly, RV completely blocked L1-RTP. Experiments using the PPARα inhibitor GW6471 or siRNA-mediated PPARα depletion showed that RV-mediated L1-RTP's inhibition depended on peroxisome proliferator-activated receptor α (PPARα). We demonstrated that RV inhibits p38 and cAMP response element binding protein phosphorylation, which are involved in MAPK signaling, and the L1-ORF1 protein's chromatin recruitment. Furthermore, RV increased the expression of sirtuin-6 (SIRT6), which inhibited the activation of L1. The sirtuins family, SIRT1, SIRT6, and SIRT7, but not SIRT3, are involved in RV-mediated inhibition of L1-RTP. Overall, our findings suggest that RV directly modulates PPARα-mediated L1-RTP in somatic cells and that MAPK signaling interacts with SIRT6 closely and may play a role in preventing human diseases such as cancer.

Involvement of retrotransposition of long interspersed nucleotide element-1 in skin tumorigenesis induced by 7,12-dimethylbenz[a]anthracene and 12-O-tetradecanoylphorbol-13-acetate.

Tumor development induced by 7,12-dimethylbenz[a]anthracene (DMBA) plus 12-O-tetradecanoylphorbol-13-acetate (TPA) is a well-characterized model of multistep carcinogenesis. DMBA mutates the Ha-ras gene, whereas TPA promotes the growth of transformed cells by activating cellular signaling molecules. It remains to be clarified how repeated TPA treatment endows transformed cells with autonomous cell growth. Long interspersed nucleotide element-1 (L1) is an endogenous retroelement, and 80-100 copies of L1 function as autonomous mobile elements. Although the L1 retrotransposition (RTP) has been found in various human tumors, implying the possible mobility of L1 during carcinogenesis, little is known about how L1-RTP arises in tumor cells, owing to a lack of experimental models. To dissect the mechanism of L1-RTP during carcinogenesis, we established a line of transgenic mice carrying human L1 and enhanced green fluorescent protein (hL1-EGFP mice) and subjected them to DMBA/TPA-induced skin tumorigenesis. Of 15 skin tumors examined, 13 were positive for L1-RTP; L1-RTP was not detected in normal skin tissues adjacent to the tumors. Moreover, nine L1-RTP-positive tumors were positive for activated Ha-ras, and immunohistochemical analysis revealed cells positive for both L1-RTP and phosphorylated Stat3, a marker of tumor cells. Additional in vivo experiments suggested that L1-RTP occurred during tumor promotion by TPA. This is the first report on the involvement of L1-RTP in chemical carcinogenesis. We propose hL1-EGFP mice as a versatile system for investigating the mode of L1-RTP in tumor development and discuss the possible role of L1-RTP in tumorigenesis.

Antitumor Effects and Tumor-specificity of Guaiazulene-3-Carboxylate Derivatives Against Oral Squamous Cell Carcinoma In Vitro.

AIM: The aim of this study was to investigate the antitumor potential of guaiazulene-3-carboxylate derivatives against oral malignant cells. MATERIALS AND METHODS: Twelve guaiazulene-3-carboxylate derivatives were synthesized by introduction of either with alkyl group [1-5], alkoxy group [6, 7], hydroxyl group [8, 9] or primary amine [10-12] at the end of sidechains. Tumor-specificity (TS) was calculated by the ratio of mean 50% cytotoxic concentration (CC50) against 3 human oral mesenchymal cell lines to that against 4 human oral squamous cell carcinoma (OSCC) cell lines. Potency-selectivity expression (PSE) was calculated by dividing TS value by CC50value against OSCC cell lines. Cell cycle analysis was performed by cell sorter. RESULTS: [6, 7] showed the highest TS and PSE values, and induced the accumulation of both subG1 and G2/M cell populations in HSC-2 OSCC cells. Quantitative structure-activity relationship analysis demonstrated that their tumor-specificity was correlated with chemical descriptors that explain the 3D shape, electric state and ionization potential. CONCLUSION: Alkoxyl guaiazulene-3-carboxylates [6, 7] can be potential candidates of lead compound for developing novel anticancer drugs.

Quantitative Structure-Cytotoxicity Relationship of Azulene Amide Derivatives.

BACKGROUND/AIM: Very few studies of anticancer activity of azulene amides led us to investigate the cytotoxicity of 21 N-alkylazulene-1-carboxamides introduced either with 3-methyl [1-7], 7-isopropyl-3-methyl [8-14] or 2-methoxy group [15-21] Materials and Methods: Tumor-specificity (TS) was calculated by the ratio of mean 50% cytotoxic concentration (CC50) against three normal human oral mesenchymal cells to that against four human oral squamous cell carcinoma (OSCC) cell lines. Potency-selectivity expression (PSE) was calculated by dividing TS value by CC50 value against OSCC cell lines. Apoptosis-inducing activity was evaluated by caspase-3 activation and appearance of subG1 cell population. RESULTS: [8-14] showed higher TS and PSE values, than [1-7] and [15-21] The most active compound [8-14] induced apoptosis in C9-22 OSCC cells at 4-times higher CC50 Quantitative structure-activity relationship analysis of [1-14] demonstrated that their tumor-specificity was correlated with chemical descriptors that explain the molecular shape and hydrophobicity. CONCLUSION: 7-Isopropyl-3-methyl-N-propylazulene-1-carboxamide [8] can be a potential candidate of lead compound for manufacturing new anticancer drug.

Comparison of the antioxidant activity of albumin from various animal species.

We measured the antioxidant activity of human, rat, bovine, rabbit, and guinea pig albumins against the superoxide, hydroxyl, and 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radicals. The albumins of different animal species did not differ in antioxidant activity against superoxide. Human and rat albumins exhibited antioxidant activity against hydroxyl radicals, but bovine, rabbit, and guinea pig albumins showed weaker antioxidant activity than human and rat albumins. Human, rat, rabbit, and guinea pig albumins, but not bovine albumin, exhibited strong antioxidant activity against DPPH radicals. Human and rat albumins with strong antioxidant activity against hydroxyl radicals contained methionine-123 in domain 1, but bovine, rabbit, and guinea pig albumins did not. Rat, rabbit, and guinea pig albumins with strong antioxidant activity against DPPH radicals had methionine-264 in domain 2. Human albumin did not have methionine-264, but methionine-298 and methionine-329 in domain 2. Bovine albumin, with the weakest antioxidant activity against DPPH radicals, contained no methionine residues in domain 2. These results suggest that methionine residues in domain 1 or 2 influence the antioxidant activity of albumin.

Quantitative Structure-Cytotoxicity Relationship of 2-Azolylchromones.

BACKGROUND/AIM: Twenty-four 2-azolylchromones were subjected to quantitative structure-activity relationship (QSAR) analysis based on their cytotoxicity and tumor specificity, in order to find their new biological activities. MATERIALS AND METHODS: Cytotoxicity against two human oral squamous cell carcinoma cell lines and two human normal oral mesenchymal cells was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method. Tumor specificity (TS) was evaluated by the ratio of the mean 50% cytotoxic concentration (CC50) against oral cells to that against oral squamous cell carcinoma cell lines. Potency-selectivity expression (PSE) value was calculated by dividing the TS value by CC50 against tumor cells. Apoptosis markers were detected by western blot analysis. Physicochemical, structural and quantum-chemical parameters were calculated based on the conformations optimized by force-field minimization. RESULTS: Three sets of 4H-1-benzopyran-4-ones with indole ring showed much higher TS values than those with pyrrole, pyrazole, imidazole, 1,2,4-triazole, 1,2,3-triazole, indazole and benzimidazole rings. Among those with an indole ring, the compound having a 6-methoxy group, that exhibited the highest cytotoxicity, yielded one to three-order higher PSE values to compared with other groups of compounds. Western blot analysis demonstrated that this compound stimulated the cleavage of caspase-3, suggesting the induction of apoptosis. QSAR analysis demonstrated that TS values were correlated with 3D shape, polarizability, ionization potential and lipophilicity. CONCLUSION: Chemical modification of the lead compound may be a potential choice for designing a new type of anticancer drug.

Quantitative Structure-Cytotoxicity Relationship of Cinnamic Acid Phenetyl Esters.

BACKGROUND/AIM: Many phenolic acid phenethyl esters possess diverse biological effects including antioxidant, cytoprotective, anti-inflammation and anti-tumor activities. However, most previous antitumor studies have not considered the cytotoxicity against normal cells. Ten cinnamic acid phenetyl esters were subjected to quantitative structure-activity relationship (QSAR) analysis, based on their cytotoxicity and tumor-specificity, in order to find their new biological activities. MATERIALS AND METHODS: Cytotoxicity against four human oral squamous cell carcinoma cell lines and three oral normal mesenchymal cells was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. Tumor specificity (TS) was evaluated by the ratio of the mean 50% cytotoxic concentration (CC50) against normal oral cells to that against human oral squamous cell carcinoma cell lines. Potency-selectivity expression (PSE) value was calculated by dividing the TS value by CC50 against tumor cells. Apoptosis markers were detected by western blot analysis. Physicochemical, structural and quantum-chemical parameters were calculated based on the conformations optimized by force-field minimization. RESULTS: Western blot analysis demonstrated that [9] stimulated the cleavage of caspase-3, suggesting the induction of apoptosis. QSAR analysis demonstrated that TS values were correlated with shape, size and ionization potential. CONCLUSION: Chemical modification of the lead compound may be a potential choice for designing a new type of anticancer drugs.

In Vitro Anti-tumor Activity of Azulene Amide Derivatives.

BACKGROUND/AIM: There exist few research articles regarding the anticancer activity of azulene-related compounds. We investigated here the relative cytotoxicity of 10 azulene amide derivatives against cancer and normal cells. MATERIALS AND METHODS: Cytotoxicity against four human oral squamous cell carcinoma (OSCC) cell lines and three human oral normal cells (gingival fibroblasts, periodontal ligament fibroblasts and pulp cells) was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetra-zolium bromide method. Antitumor activity was evaluated by tumor-specificity (TS) (ratio of mean 50% cytotoxic concentration (CC50) against normal cells to that against OSCC cell lines) and potency-selectivity expression (PSE) (ratio of TS to CC50 against tumor cells). Apoptosis-inducing activity was evaluated by cleavage of poly ADP-ribose polymerase and caspase-3 with western blot analysis. RESULTS: N-Propylguaiazulenecarboxamide [1] showed the highest TS and PSE values, compared to that of doxorubicin, and induced apoptosis in two OSCC cell lines. QSAR analysis demonstrated that their tumor-specificity of azulene amide derivatives was correlated with hydrophobicity and molecular shape. CONCLUSION: Compound [1] can be considered as a lead compound for manufacturing new anticancer drug candidates.

In Vitro Antitumor Activity of Alkylaminoguaiazulenes.

BACKGROUND/AIM: Guaiazulene (1,4-dimethyl-7-isopropylazulene) is present in several essential oils of medicinal and aromatic plants. There exist few studies that investigated the anticancer activity of guaiazulenes. We investigated the relative cytotoxicity of 10 alkylaminoguaiazulene derivatives towards both cancer and normal cells. MATERIALS AND METHODS: Cytotoxicity towards four human oral squamous cell carcinoma (OSCC) cell lines and five types of human normal oral cells (gingival fibroblasts, periodontal ligament fibroblasts, pulp cells and keratinocytes, gingival epithelial progenitors) was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. Tumor specificity (TS) was evaluated as the ratio of the mean 50% cytotoxic concentration against normal oral cells to that against OSCC cell lines. Apoptosis-inducing activity was evaluated by cleavage of poly ADP-ribose polymerase and caspsase-3 with western blot analysis. RESULTS: Validity of the present TS measurement method was confirmed using methotrexate. With increasing length of the alkyl group of alkylaminoguaiazulene derivatives, cytotoxicity increased. Introduction of oxygen, nitrogen or sulfur atom into the alkyl group slightly reduced cytotoxicity. Most compounds had very low TS, no synergistic action with methotrexate and doxorubicin, nor did they induce apoptosis of OSCC cells. On the other hand, compound [10], containing a morpholino group, induced apoptosis of OSCC cells. CONCLUSION: The cytotoxicity of alkylaminoguaiazulenes is not always coupled with TS and apoptosis-inducing activity.

Quantitative Structure-Cytotoxicity Relationship of 2-(N-cyclicamino)chromone Derivatives.

BACKGROUND/AIM: 4H-1-Benzopyran-4-ones (chromones) have provided backbone structure for the chemical synthesis of potent anticancer drugs. In this study, the cytotoxicity of fifteen 2-(N-cyclicamino)chromone derivatives was investigated and subjected to quantitative structure-activity relationship (QSAR) analysis. MATERIALS AND METHODS: Cytotoxicity against four human oral squamous cell carcinoma cell lines and three oral normal mesenchymal cells was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. Tumor specificity (TS) was evaluated by ratio of mean 50% cytotoxic concentration (CC50) against normal oral cells to that against human oral squamous cell carcinoma cell lines. Potency-selectivity expression (PSE) value was calculated by dividing the TS value by CC50 against tumor cells. Apoptosis induction was evaluated by morphological observation, western blot analysis and cell-cycle analysis. For QSAR analysis, a total of 3,089 physicochemicals, structural and quantum chemical features were calculated from the most stabilized structure optimized using Corina. RESULTS: 7-Methoxy-2-(4-morpholinyl)-4H-1-benzopyran-4-one (5c) showed highest tumor-specificity, comparable with that of doxorubicin, without inducing apoptosis. Tumor-specificity of fifteen 2-(N-cyclicamino) chromones was correlated with molecular shape, especially 3D-structure. CONCLUSION: Chemical modification of 5c may be a potential choice for designing a new type of anticancer drugs.

Quantitative Structure-Cytotoxicity Relationship of Pyrano[4,3-b]chromones.

BACKGROUND/AIM: 4H-1-Benzopyran-4-one (chromone) provides a backbone structure for the chemical synthesis of potent anticancer drugs. Since studies of the biological activity of pyrano[4,3-b]chromones are limited, we investigated a total of 20 pyrano[4,3-b]chromones (10 sets of diastereomers) for their cytotoxicity against four human oral squamous cell carcinoma (OSCC) cell lines and human normal oral cells, and then carried out a quantitative structure-activity relationship (QSAR) analysis. MATERIALS AND METHODS: Cytotoxicity was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method. Tumor-specificity (TS) was evaluated by the ratio of mean 50% cytotoxic concentration (CC50) against normal oral cells to that against human OSCC cell lines. Potency-selectivity expression (PSE) value was calculated by dividing the TS value by the CC50 against tumor cells. Apoptosis induction was evaluated by morphological observation, western blot analysis and cell-cycle analysis. For QSAR analysis, a total of 3,072 physicochemical, structural and quantum chemical features were calculated from the most stabilized structure optimized using CORINA. RESULTS: 8-Chloro-4,4a-dihydro-3-methoxy-3-methyl-3H,10H-pyrano[4,3-b][1]benzopyran-10-one (16) and 3-ethoxy-4,4a-dihydro-8-methoxy-3H,10H-pyrano[4,3-b][1]benzopyran-10-one (17) had the highest TS, higher than that of 5-flurouracil and melphalan, without induction of apoptosis. Compound 16 induced cytostatic growth inhibition and much lower cytotoxicity against human normal oral keratinocytes compared to doxorubicin. TS of 20 pyrano[4,3-b]chromones was correlated with 3D structure, polarity, ionic potential and electric state. CONCLUSION: Chemical modification of 16 may be a potential choice for designing a new type of anticancer drug.

Quantitative Structure-Cytotoxicity Relationship of 3-(N-Cyclicamino)chromone Derivatives.

BACKGROUND/AIM: 4H-1-Benzopyran-4-ones (chromones) provide a backbone structure for the chemical synthesis of potent anticancer drugs. In contrast to 2-(N-cyclicamino)chromones, the biological activity of 3-(N-cyclicamino)chromones has not been reported. In this study, cytotoxicity of 15 3-(N-cyclicamino)chromone derivatives was investigated and subjected to quantitative structure-activity relationship (QSAR) analysis. MATERIALS AND METHODS: Cytotoxicity against four human oral squamous cell carcinoma cell lines and three oral normal mesenchymal cells was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. Tumor-specificity (TS) was evaluated as the ratio of mean 50% cytotoxic concentration (CC50) against normal oral cells to that against human oral squamous cell carcinoma cell lines. Potency-selectivity expression (PSE) value was calculated by dividing the TS value by the CC50 against tumor cells. Apoptosis induction was evaluated by morphological observation, western blot analysis and cell-cycle analysis. For QSAR analysis, a total of 3,096 physicochemical, structural and quantum chemical features were calculated from the most stabilized structure optimized using CORINA. RESULTS: 3-(4-phenyl-1-piperazinyl)-4H-1-benzopyran-4-one (3a) had the highest tumor specificity, comparable with that of melphalan, without induction of apoptosis. Compound 3a caused cytostatic growth inhibition and had much lower cytotoxicity against human oral keratinocytes compared to doxorubicin. TS of the 15 3-(N-cyclicamino)chromones was correlated with 3D structure and lipophilicity. CONCLUSION: Chemical modification of 3a may be a potential choice for designing a new type of anticancer drug.