Search

Cisplatin (CDDP) is a platinum-based anticancer drug widely prescribed for its effectiveness in treating various forms of cancer. However, its major side effect is nephrotoxicity. Although several methods have been developed to mitigate CDDP-induced nephrotoxicity, an optimal approach has yet to be established. This study aimed to investigate the "chronotoxicity" of CDDP as a potential strategy to reduce its side effects. Male ICR mice were treated with CDDP (20 mg/kg, intraperitoneal injection, one shot) at zeitgeber time (ZT) 2 or ZT14 (light or dark phase). After 72 h, we collected plasma and kidney and evaluated several markers. We found that body weight change between ZT2 and ZT14 by CDDP was comparable. In contrast, many toxicological factors, such as plasma blood urine nitrogen, plasma creatinine, renal oxidative stress (malondialdehyde), DNA damage (γH2AX), acute kidney injury biomarker (KIM-1), and inflammation (Tnfα), were significantly induced at ZT14 compared to than that of ZT2. Our present data suggested that chronotoxicology might provide beneficial information on the importance of administration timings for toxic evaluations and unacceptable side effects., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The present study, to the best of our knowledge, is the first systematic study of the inhibitory effects of palmitoyl piperidinopiperidine (PPI; Japan Patent no. 5597427), on colon carcinogenesis. PPI exhibited marked growth inhibitory activity in several human colon carcinoma cell lines, with IC50 values of approximately 0.5‑2.2 µM. In silico docking analysis indicated that PPI could bind to the SH2 domain of signal transducer and activator of transcription 3 (STAT3). PPI markedly inhibited the transcriptional activity of the SW837 cell line. Flowcytometric analysis demonstrated that PPI induced an increase in the number of cells in the G1 phase of the cell cycle, and induced sub‑G1 fractions of cells at a higher concentration level of PPI. In the HT29 and SW837 cells, western blot analyses exhibited that in whole cell lysates, PPI induced a marked decrease in the expression levels of p‑STAT3, but not in the levels of STAT3 in these cells. PPI also induced a marked decrease in the expression levels of both STAT3 and p‑STAT3 in the chromatin fraction. In addition, PPI affected the protein expression levels of cyclin D1, p53, Bcl‑2, Bcl‑xL and vascular endothelial growth factor (VEGF). In the HT29 cells, PPI induced a marked and dose‑dependent increase in the expression levels of Bax, cleaved caspase‑3, cleaved caspase‑7, cleaved caspase‑8, cleaved caspase‑9 and cleaved poly (ADP‑ribose) polymerase (PARP). In animal model systems, PPI inhibited the growth of implanted carcinoma cells, and also induced a significant decrease in the multiplicity of colonic aberrant crypt foci. In addition, a marked and dose‑dependent inhibition of angiogenesis of the chick chorioallantoic membrane was observed. As regards the possible molecular mechanisms, it is suggested that the inhibition of STAT3 by PPI may affect the function of molecules that are related to apoptosis, angiogenesis and cell cycle progression, eventually contributing to the PPI‑induced growth inhibitory effects.

Pancreatic ductal adenocarcinoma (PDA) is a highly lethal disease, which is usually diagnosed in an advanced stage. We have established transgenic rats carrying a mutated K-ras gene controlled by Cre/loxP activation. The animals develop PDA which is histopathologically similar to that in humans. Previously, we reported that serum levels of N-ERC/mesothelin were significantly higher in rats bearing PDA than in controls. In the present study, to determine whether serum levels of N-ERC/mesothelin correlated with tumor size, we measured N-ERC/mesothelin levels in rats bearing PDA. Increased serum levels of N-ERC/mesothelin correlated with increased tumor size. This result indicates an interrelationship between the serum level of N-ERC/mesothelin and tumor size. We next investigated the effect of chemotherapy on serum N-ERC/mesothelin levels. Rat pancreatic cancer cells were implanted subcutaneously into the flank of NOD-SCID mice. In the mice treated with 200 mg/kg gemcitabine, tumor weight and the serum level of N-ERC/mesothelin were significantly decreased compared to controls. These results suggest that serum N-ERC/mesothelin measurements might be useful for monitoring response to therapy.

Acyclic retinoid (ACR), a novel synthetic retinoid, has been demonstrated by us to inhibit the in vitro growth of human hepatoma cells, and this effect was associated with modification of cell cycle control molecules, suggesting that this agent may be useful in the chemoprevention and therapy of various types of malignancies. However, whether or not ACR exerts anticancer activities on human colon carcinoma cells has not yet been elucidated. The purpose of this study was to examine the inhibitory effects of ACR in human colon carcinoma cells and to characterize the molecular mechanism of action of this agent. ACR inhibited the growth of the HCT116 and SW480 human colon carcinoma cell lines with IC50 values of about 30 and 60 microM, respectively. ACR also induced G1-phase cell cycle arrest and apoptosis in these cell lines. When the HCT116 cells were treated with 5-25 microM ACR, there was a marked decrease in the cellular levels of cyclin D1 mRNA and an approximate 2.5- to 3-fold increase in those of p21CIP1 mRNA, and this induction occurred via a p53-independent mechanism. Furthermore, ACR induced a dose-dependent mRNA elevation of differentiation markers at concentrations of ACR that affect the levels of expression of p21CIP1. These novel results suggest that ACR inhibits cell proliferation by inducing G1 arrest and apoptosis and that cyclin D1 and p21CIP1 play critical roles in the molecular mechanisms of growth inhibition and differentiation induced by ACR. Collectively, these findings provide further evidence that ACR may be a potential agent for the chemoprevention and therapy of human colon cancer.

Acyclic retinoid (ACR), a novel synthetic retinoid, has recently been demonstrated by us to inhibit the in vitro growth of human hepatoma cells, and this effect was associated with decreased expression of cell cycle-related molecules. These results, taken together with previous in vitro and clinical studies with ACR, suggest that this agent may be useful in the chemoprevention and therapy of hepatoma and possibly other human malignancies. In the present study, we further examined the molecular effects of ACR on the HepG2 human hepatoma cell line, focusing on the expression of nuclear retinoid receptors and the cell cycle inhibitor protein p21(CIP1). Reverse transcription-PCR assays and Western blot analyses indicated that these cells express retinoic acid receptors (RARs) alpha, beta, and gamma, retinoid X receptors (RXRs) alpha and beta, and peroxisome proliferator-activated receptors (PPAR) gamma mRNA. Treatment with ACR caused a rapid induction within 3 h of RARbeta mRNA and the related protein, but there was no significant change in the levels of the mRNA or proteins for RARs alpha and gamma, RXRs alpha and beta, and PPARgamma. There was also a rapid increase in p21(CIP1) mRNA and protein in HepG2 cells treated with ACR, and this induction occurred via a p53-independent mechanism. In transient transfection reporter assays, we cotransfected the retinoic acid response element-chloramphenicol acetyltransferase (CAT) reporter gene into HepG2 cells together with a RARbeta expression vector. RARbeta expression markedly stimulated CAT activity (up to about 4-fold) after the addition of ACR. However, CAT activity in the presence of ACR was only about 2-fold higher than that in the absence of ACR, when cells were cotransfected with RARs alpha and gamma or RXRalpha. These findings suggest that the growth inhibitory effects of ACR are mediated at least in part through RARbeta and that both RARbeta and p21(CIP1) play critical roles in the molecular mechanisms of growth inhibition induced by ACR.

We described recently the growth inhibitory effects of the novel compound acyclic retinoid (ACR) in human hepatoma cell lines (M. Suzui et al., Cancer Res., 62: 3997-4006, 2002). In this study we examined the cellular and molecular effects of ACR on human squamous cell carcinoma (SCC) cells. ACR inhibited growth of the esophageal SCC cell line HCE7, and the head and neck SCC cell lines YCU-N861 and YCU-H891, with IC(50) values of approximately 10, 25, and 40 microM, respectively. Detailed studies were then done with HCE7 cells. Treatment of these cells with 10 microM ACR caused an increase of cells in G(0)-G(1) and induced apoptosis. This was associated with two phases of molecular events. During phase 1, which occurred within 6-12 h, there was an increase in the retinoic acid receptor beta (RARbeta) and p21(CIP1) proteins, and their corresponding mRNAs, and a decrease in the hyperphosphorylated form of the retinoblastoma protein. During phase 2, which occurred at approximately 24 h, there was a decrease in the cellular level of transforming growth factor alpha, and the phosphorylated (i.e., activated) forms of the epidermal growth factor receptor, Stat3, and extracellular signal-regulated kinase proteins, and a decrease in both cyclin D1 protein and mRNA. Reporter assays indicated that ACR inhibited the transcriptional activity of the cyclin D1, c-fos, and activator protein promoters. On the other hand, ACR markedly stimulated the activity of a retinoic acid response element-CAT reporter when the cells were cotransfected with a RARbeta expression vector. A hypothetical model explaining these two phases is presented. The diverse effects that we obtained with ACR suggest that this agent might be useful in the chemoprevention and/or therapy of human SCCs.

In a recent study on head and neck squamous cell carcinoma (HNSCC) cells we found that epigallocatechin-3-gallate (EGCG), a major biologically active component of green tea, inhibited activation of the epidermal growth factor receptor (EGFR) and related signaling pathways. Since activation of EGFR signaling pathways is associated with angiogenesis, we examined the effects of EGCG on vascular endothelial growth factor (VEGF) production by YCU-H891 HNSCC and MDA-MB-231 breast carcinoma cell lines, because we found that both of these cell lines display autocrine activation of transforming growth factor-alpha (TGF-alpha)/EGFR signaling and produce high levels of VEGF. Treatment with EGCG inhibited the constitutive activation of the EGFR, Stat3, and Akt in both cell lines. These changes were associated with inhibition of VEGF promoter activity and cellular production of VEGF. Mechanistic studies indicated that inhibition of Stat3, but not mitogen-activated protein kinase kinase (MEK)1 or phosphatidylinositol 3'-kinase (PI3K), significantly decreased VEGF promoter activity. However, the inhibitory effects of a dominant negative Stat3 on VEGF expression was not as strong as that produced by EGCG. An analysis of alternative pathways indicated that EGCG strongly inhibited the constitutive activation of NF-kappa B in both cell lines, and an NF-kappa B inhibitor strongly inhibited VEGF production. These results suggest that EGCG inhibits VEGF production by inhibiting both the constitutive activation of Stat3 and NF-kappa B, but not extracellular-signal-regulated kinase (ERK) or Akt, in these cells. Therefore, EGCG may be useful in treating HNSCC and breast carcinoma because it can exert both antiproliferative and antiangiogenic activities.

Acyclic retinoid (ACR), a novel synthetic retinoid, can prevent the recurrence of human hepatoma after surgical resection of primary tumors, but the molecular mechanisms by which ACR exerts antitumor effects are not known. In this study, we found that ACR inhibited the growth of three human hepatoma cell lines. In HepG2 cells, this inhibition was associated with an arrest of the cell cycle in G(0)-G(1), increased cellular levels of p21(CIP1), decreased levels of the hyperphosphorylated form of the retinoblastoma protein, and decreased levels of cyclin D1, but no significant changes were seen in the levels of the p16(INK4a), p27(KIP1), cyclin-dependent kinase 4, cyclin-dependent kinase 6, glycogen synthase kinase 3beta, or beta-catenin proteins. ACR also caused a decrease in the level of cyclin D1 mRNA. Cotreatment of HepG2 human hepatoma cells with the proteasome inhibitor N-acetyl-Leu-Leu-norleu-al did not prevent the ACR-induced decrease in cyclin D1 protein, in contrast to the protective effect of N-acetyl-Leu-Leu-norleu-al on the cyclin D1 protein in cells treated with all-trans-retinoic acid. In transient transfection reporter assays, ACR, but not all-trans-retinoic acid, inhibited transcription from the cyclin D1 promoter. As reported previously in colon carcinoma cells, we found that in hepatoma cells, cyclin D1 promoter activity is markedly stimulated by the beta-catenin/T-cell factor pathway. Nevertheless, even in the presence of excess beta-catenin, ACR markedly inhibited the transcriptional activity of the cyclin D1 promoter. This is the first systematic study of the inhibitory effects of ACR, or any other retinoid compound, on beta-catenin/T-cell factor-stimulated cyclin D1 promoter activity in human tumor cells. These novel effects of ACR provide further evidence that ACR may be a valuable agent in the chemoprevention and therapy of hepatoma and possibly other human malignancies.

The antitumor effects of the green tea compound epigallocatechin-3-gallate (EGCG) have not been studied in detail previously in head and neck squamous cell carcinoma (HNSCC) cells. Overexpression of the epidermal growth factor receptor (EGFR) occurs frequently in HNSCC, which is an adverse prognostic factor. Therefore, we examined in detail the molecular effects of EGCG on two human HNSCC cell lines, YCU-N861 and YCU-H891, focusing on the EGFR signaling pathway. The 70% lethal dose (IC(70)) of EGCG for both cell lines was 10 microg/ml. Treatment with EGCG increased the proportion of cells in the G(1) phase of the cell cycle and induced apoptosis. In cells treated with EGCG, there was a decrease in the cyclin D1 protein, an increase in the p21(Cip1) and p27(Kip1) proteins, and a reduction in the hyperphosphorylated form of pRB, changes that may account for the arrest in G(1). EGCG also caused a decrease in the Bcl-2 and Bcl-X(L) proteins, an increase in the Bax protein, and activation of caspase 9, suggesting that EGCG induces apoptosis via a mitochondrial pathway. Treatment with EGCG inhibited phosphorylation of the EGFR, signal transducer and activator of transcription3 (Stat3), and extracellular regulated kinase (ERK) proteins and also inhibited basal and transforming growth factor-alpha-stimulated c-fos and cyclin D1 promoter activity. EGCG at 0.1 microg/ml (a concentration found in serum after oral administration) markedly enhanced the growth-inhibitory effects of 5-fluorouracil. Taken together, these findings provide insights into molecular mechanisms of growth inhibition by EGCG and suggest that this naturally occurring compound may be useful, when used alone or in combination with other agents, in the chemoprevention and/or treatment of HNSCC.

The present study was designed to investigate the modifying effects of dietary 5-hydroxy-4-(2-phenyl-(E)-ethenyl)-2(5H)-furanone (KYN-54), a new synthetic retinoidal butenolide, during the post-initiation phase on azoxymethane (AOM)-induced rat intestinal carcinogenesis. The number of aberrant crypt foci (ACF) in rat colon, colonic ornithine decarboxylase (ODC) activity and bromodeoxy-uridine (BrdUrd) labeling index in rat colonic epithelium were also assessed. At 7 weeks of age, male F344 rats (except the KYN-54 alone and control groups) were given weekly s.c. injections of AOM at 15 mg/kg body wt for 3 weeks. Starting 1 week after the last injection of AOM, rats (except the control group) were fed a diet containing KYN-54 at concentrations of 100 or 200 p.p.m. throughout the experiment. All animals were necropsied at 32 weeks after the start of the experiment. Compared with the AOM alone group, KYN-54 at both doses reduced the incidence and multiplicity of tumors in entire intestine (small and large intestines). In the 200 p.p.m. KYN-54 fed group especially, tumor incidence and multiplicity in the entire intestine were lower compared with the AOM alone group (P < 0.005 and P < 0.05 respectively). Also, the number of ACF/cm2 colon in the groups of rats treated with AOM and KYN-54 at both doses were significantly lower than that of rats treated with AOM alone (P < 0.05). Colonic ODC activity and BrdUrd labeling index in the groups of rats treated with AOM and KYN-54 at both doses were slightly lower than those treated with AOM alone. KYN-54 at 200 p.p.m. significantly lowered BrdUrd labeling index induced by AOM (P < 0.005). These results suggest that KYN-54 might be a promising chemopreventive agent for intestinal neoplasia.

Our previous study has shown that dietary administration of protocatechuic acid (PCA) acts as potential chemopreventive agent in inhibiting diethylnitrosamine-induced liver carcinogenesis in male F344 rats. The present study was designed to determine the modifying effect of PCA on azoxymethane (AOM)-induced colon carcinogenesis in male F344 rats and the effect on intermediate biomarkers, i.e., colonic mucosal ornithine decarboxylase activity and colonic epithelial proliferation, which can be used as effective predictors of colon cancer. Staring at 6 weeks of age, groups of animals were fed the basal diet and experimental diet containing PCA at dose levels of 250, 500, and 1000 ppm. At 7 weeks of age, all animals except the PCA alone group (1000 ppm) and untreated controls were given s.c. injections of AOM at a dose level of 15 mg/kg body weight/week for 3 weeks. PCA at 3 doses was fed during the initiation phase (before 1 week, during, and after 1 week of AOM exposure) or postinitiation phase (for 28 weeks starting 1 week after the last injection of AOM). All animals were then killed at 32 weeks after the start and colonic tumor incidence and multiplicity were determined. Animals intended for cell proliferation study were given injections of bromodeoxyuridine/5-fluoro-2'-deoxyuridine (1 ml/100 g body weight) 1 h prior to be killing. The rate of colonic cell proliferation in the distal portion was assessed by immunohistochemistry using antibromodeoxyuridine and by counting silver-stained nucleolar organizer regions protein. The colonic mucosal ornithine decarboxylase activity was also measured at the termination. The results indicate that dietary PCA administration at 500 and 1000 ppm during the initiation or postinitiation phase significantly inhibited intestinal carcinogenesis induced by AOM as revealed by the reduction of tumor incidence and multiplicity. The data also demonstrate that PCA at 500 ppm and 1000 ppm significantly inhibited bromodeoxyuridine labeling index and also silver-stained nucleolar organizer regions protein number at three doses when animals were fed PCA at the initiation or postinitiation stage. Also, feeding of PCA at 1000 ppm during the initiation and postinitiation phase exerted a pronounced inhibitory effect on the colonic ornithine decarboxylase levels. PCA feeding did not cause any toxicity. These results demonstrate that PCA is a possible new chemopreventive agent for colon carcinogenesis through the suppression of manifestation of intermediate biomarkers induced by AOM, although the precise mechanisms of PCA-induced inhibition during the initiation and postinitiation phases remain to be elucidated.