Subchronic toxicity and toxicogenomic evaluation of tamoxifen citrate + bexarotene in female rats

Synergistic action of cilnidipine and bexarotene in mitigating cholestatic liver damage: role of FXR signaling cascade

Cholestasis, a condition characterized by impaired bile flow, can lead to severe liver damage if left untreated. Current therapeutic options are limited, necessitating the development of novel treatment strategies. This study investigated the synergistic action of cilnidipine, a calcium channel blocker, and bexarotene, a retinoid X receptor (RXR) agonist, in mitigating cholestatic liver damage induced by alpha-naphthyl isothiocyanate (ANIT) in rats. The study aimed to elucidate the role of the farnesoid X receptor (FXR) signaling cascade in the protective effects of the combined treatment. Rats were divided into three groups: a negative control group, an ANIT-treated group, and a group pretreated with cilnidipine and bexarotene before ANIT administration. Biochemical markers of liver function, oxidative stress, and inflammation were assessed, along with histological examination of liver tissue. The expression of genes related to the FXR signaling pathway was also evaluated using quantitative polymerase chain reaction (qPCR). The results demonstrated that pretreatment with cilnidipine and bexarotene significantly attenuated ANIT-induced cholestatic liver damage, as evidenced by improved liver function markers, reduced oxidative stress and inflammation, and ameliorated histological changes. Furthermore, the combined treatment upregulated the expression of FXR and its target genes, suggesting that the protective effects may be mediated through the activation of the FXR signaling cascade. These findings highlight the potential of cilnidipine and bexarotene as a novel therapeutic approach for the management of cholestatic liver disorders and provide insights into the underlying molecular mechanisms involving the FXR signaling pathway.

Novel insights into bexarotene's role in preventing cholestasis: mechanisms and implications

Cholestasis is defined as an impairment in the flow of bile, resulting in the accumulation of its components. Despite ursodeoxycholic acid (UDCA) being the only FDA-approved drug for cholestasis, it has little value in treating or preventing cholestasis; hence, new medications are required to treat these illnesses. The farnesoid X receptor (FXR) maintains bile acid (BA) homeostasis. It exists as heterodimers with retinoid X receptor (RXR) and responds to ligands that bind to any one of the partners and are activated synergistically in the presence of both. The hepatoprotective effect of bexarotene (Bex) against cholestasis liver injury induced by α-naphthyl isothiocyanate (ANIT) was evaluated in male Wistar albino rats. Our study demonstrates that compared to the ANIT group, Bex improves liver function tests, liver histology, and considerably reduces inflammatory mediators. Additionally, antioxidant levels increased significantly. Besides that, Bex upregulates the gene expression of FXR, bile salt export pump, hepatocyte nuclear factor 1α, and small heterodimer partner. Moreover, it enhances antioxidative nuclear factor erythroid 2-related factor gene expression and the expression of the NAD(P)H quinone oxidoreductase 1, and heme-oxygenase 1 protein targets in the rats' livers, reinforcing its hepatoprotective potential. Furthermore, Bex increases protein expressions of FXR, The bile salt export pump, and sirtuin 1 levels in the rats' livers. This study demonstrates that Bex protects against ANIT-induced cholestasis. This protective strategy involves controlling BA metabolism, inhibiting inflammatory mediators, and reducing oxidative stress.

Protective role of olive oil extract of propolis on short and long-term administration of tamoxifen in rats

Tamoxifen (TAM) is an antiestrogenic agent used for adjuvant treatment in estrogen receptor-positive breast cancers in the pre/post-menopausal period. This study, it was aimed to determine the effect of olive oil extract of propolis (OEP) on short and long-term administration of TAM in rats. Wistar albino rats were divided into groups with eight animals in each. Groups: control, OEP, TAM, and OEP + TAM. At the end of the experiment, oxidative stress tests were performed with Enzyme-Linked ImmunoSorbent Assay (ELISA) on blood and tissue samples (liver, kidney, and ovary) taken from rats. After single-dose TAM administration, there was a significant increase in red blood cell, hematocrit, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration levels compared to the control group, a decrease in low-density lipoprotein (LDL) value, a significant increase in liver enzymes and fasting glucose values was detected compared with the control and propolis groups. A normalizing effect was observed in the group given OEP and TAM combined. The increase in Malondialdehyde (MDA) and the decrease in enzyme activities in tissues are also noteworthy. Propolis application reduced the tissue damage caused by TAM. In addition, improved cytokine levels, which increased with TAM administration. It has been concluded that OEP can be given in supportive treatment, as it improves hematological and antioxidant parameters in TAM treatment.

Chlorogenic acid abates oxido-inflammatory and apoptotic responses in the liver and kidney of Tamoxifen-treated rats

Plant-derived phenolics are utilized as chemopreventive agents to abate adverse toxic responses associated with drug-induced damages. Tamoxifen (TAM)-a chemotherapeutic agent-is used in managing all stages of hormone-dependent breast cancer. Notwithstanding TAM's clinical side effect-including hepatic toxicity-its use is commonplace. The present study investigates the effect of Chlorogenic acid (CGA: 25 and 50 mg kg-1; per os (p.o)) reported to exhibit various beneficial properties, including antioxidative effect against TAM (50 mg/kg; p.o.)-induced hepatorenal toxicities in rats treated as follows: Control, CGA, or TAM alone, and rats co-treated with CGA and TAM for 2 weeks. Biomarkers of hepatorenal function, oxido-inflammatory stress, and hepatorenal histopathology were performed. We observed that TAM alone decreased relative organ weights (ROW), marginally impacted rat's survivability, and significantly (P < 0.05) increased hepatorenal toxicities and reactive oxygen and nitrogen species (RONS). TAM decreased (P < 0.05) antioxidant, anti-inflammatory cytokine (IL-10), besides increase in (P < 0.05) lipid peroxidation (LPO), pro-inflammatory cytokines (IL-1β, TNF-α), nitric oxide (NO), xanthine oxidase (XO), myeloperoxidase (MPO), and apoptotic caspases (Casp-3 and -9) levels. These biochemical alterations were accompanied by morphological lesions in experimental rats' liver and kidney. Conversely, that CGA dose-dependently relieved TAM-mediated toxic responses, restored antioxidants capacities, reduced oxidative stress, pro-inflammatory cytokines levels, and Casp-3 and -9 activities in experimental rats. Furthermore, CGA protected against lesions observed in the liver and kidney of rats treated with TAM alone. Overall, CGA blocked TAM-mediated hepatorenal injuries associated with pro-oxidative, inflammatory, and apoptotic mechanisms. CGA may serve as a chemoprotective agent boosting patients prognosis undergoing TAM chemotherapy.

Exploring novel mechanistic insights in Alzheimer's disease by assessing reliability of protein interactions

Protein interaction networks are widely used in computational biology as a graphical means of representing higher-level systemic functions in a computable form. Although, many algorithms exist that seamlessly collect and measure protein interaction information in network models, they often do not provide novel mechanistic insights using quantitative criteria. Measuring information content and knowledge representation in network models about disease mechanisms becomes crucial particularly when exploring new target candidates in a well-defined functional context of a potential disease mechanism. To this end, we have developed a knowledge-based scoring approach that uses literature-derived protein interaction features to quantify protein interaction confidence. Thereby, we introduce the novel concept of knowledge cliffs, regions of the interaction network where a significant gap between high scoring and low scoring interactions is observed, representing a divide between established and emerging knowledge on disease mechanism. To show the application of this approach, we constructed and assessed reliability of a protein-protein interaction model specific to Alzheimer’s disease, which led to screening, and prioritization of four novel protein candidates. Evaluation of the identified candidates showed that two of them are already followed in clinical trials for testing potential AD drugs.

Retinoid receptors in gastric cancer: expression and influence on prognosis

BACKGROUND

Gastric cancer is frequently lethal despite aggressive multimodal therapies, and new treatment approaches are therefore needed. Retinoids are potential candidate drugs: they prevent cell differentiation, proliferation and malignant transformation in gastric cancer cell lines. They interact with nuclear retinoid receptors (the retinoic acid receptors [RARs] and retinoid X receptors [RXRs]), which function as transcription factors, each with three subclasses, α, β and γ. At present, little is known about retinoid expression and influence on prognosis in gastric cancers.

PATIENTS AND METHODS

We retrospectively analyzed the expression of the subtypes RARα, RARβ, RARγ, RXRα, RXRβ, RXRγ by immunohistochemistry in 147 gastric cancers and 51 normal gastric epithelium tissues for whom clinical follow-up data were available and correlated the results with clinical characteristics. In addition, we quantified the expression of retinoid receptor mRNA using real- time PCR (RT-PCR) in another 6 gastric adenocarcinoma and 3 normal gastric tissues. From 2008 to 2010, 80 patients with gastric cancers were enrolled onto therapy with all-trans-retinoic acid (ATRA).

RESULTS

RARα, RARβ, RARγ and RXRγ positively correlated with each other (p<0.001) and demonstrated significantly lower levels in the carcinoma tissue sections (p<0.01), with lower RARβ, RARγ and RXRα expression significantly related to advanced stages (p<=0.01). Tumors with poor histopathologic grade had lower levels of RARα and RARβ in different histological types of gastric carcinoma (p<0.01). Patients whose tumors exhibited low levels of RARa expression had significantly lower overall survival compared with patients who had higher expression levels of this receptor (p<0.001, HR=0.42, 95.0% CI 0.24-0.73), and patients undergoing ATRA treatment had significantly longer median survival times (p=0.007, HR=0.41, 95.0% CI 0.21-0.80).

CONCLUSIONS

Retinoic acid receptors are frequently expressed in epithelial gastric cancer with a decreased tendency of expression and RARa may be an indicator of a positive prognosis. This study provides a molecular basis for the therapeutic use of retinoids against gastric cancer.

Murine oncogenicity and pharmacokinetics studies of 9-cis-UAB30, an RXR agonist, for breast cancer chemoprevention

The synthetic retinoic acid analog, 9-cis-UAB30 [(2E,4E,6Z,8E)-8-(3',4'-dihydro-1'(2'H)-naphthalen-1'-ylidene)-3,7-dimethyl-2,4,6-octatrienoic acid], is a specific ligand for the retinoid X receptor. Murine oncogenicity and pharmacokinetics studies were performed as part of the preclinical development of 9-cis-UAB30 for breast cancer chemoprevention. In the oncogenicity study, TSG-p53((+/-)) (p53 knockout) mice (25 per sex per group) received daily gavage exposure to 9-cis-UAB30 doses of 0 (control), 30, 100, or 300 mg/kg/d for 6 months. Positive controls received p-cresidine (400 mg/kg/d) for 6 months. 9-cis-UAB30 had no biologically significant effects on survival, body weight, body weight gain, clinical signs, hematology, or clinical chemistry but induced dose-related hepatomegaly in both sexes and decreased thymus weights in high-dose females. Gross and microscopic pathology provided no evidence of 9-cis-UAB30 toxicity or oncogenicity; by contrast, p-cresidine induced urinary bladder neoplasms in more than 60% of male and female mice. It was concluded that 9-cis-UAB30 is not oncogenic in p53((+/-)) mice. In the pharmacokinetics study, C57BL/6 mice received daily gavage exposure to 9-cis-UAB30 (100 or 300 mg/kg/d) for 1 or 7 days. Pharmacokinetic parameters were similar after 1 and 7 days of dosing. Dose-related peak plasma levels of 9-cis-UAB30 were seen between 0.25 and 3 hours; volume of distribution was comparable at both dose levels. Increases in area under the curve were less than proportional to dose and were associated with an increased rate of apparent clearance and decreased elimination half-life. These results suggest decreased absorption and/or possible induction of clearance mechanisms. Enzyme induction may underlie the hepatomegaly seen in mice treated with 9-cis-UAB30 for 6 months in the oncogenicity study.