Involvement of hypothalamic cyclooxygenase-2, interleukin-1β and melanocortin in the development of docetaxel-induced anorexia in rats

Effects of maternal taxane chemotherapy exposure on daughters' ovarian reserve and fertility potential

OBJECTIVE

To investigate the long-term effects of in utero taxane exposure on exposed daughters' ovarian reserve and reproductive potential.

DESIGN

Pregnant dams were treated with a single, human-relevant animal-equivalent dose of saline, docetaxel, or paclitaxel at embryonic day 16.5. In utero-exposed daughters were aged to multiple postnatal time points for ovarian and endocrine analysis or were bred to assess fertility and fecundity. Granddaughters of treated dams were assessed also for ovarian follicle composition and atresia.

SETTING

Laboratory study.

ANIMALS

C57BL/6 mice.

INTERVENTION(S)

In utero exposure to saline, docetaxel, or paclitaxel.

MAIN OUTCOME MEASURE(S)

Ovarian follicle composition, rates of follicle atresia, and rates of multioocyte follicles were analyzed in all exposure groups. Serum hormone levels and oocyte retrieval outcomes following ovarian hyperstimulation were also assessed. Finally, animals from all exposure groups were bred with the number of litters, pups per litter, live births, interlitter time interval, and age at the last litter analyzed.

RESULT(S)

We found that docetaxel and paclitaxel exposure in utero results in ovarian toxicity later in life, significantly affecting folliculogenesis as well as increasing the rate of follicular abnormalities, including follicle atresia and multioocyte follicles. Furthermore, viability staining indicates that the ovaries of daughters exposed to taxanes in utero demonstrate a significantly higher number of terminal deoxynucleotidyl transferase dUTP nick end labeling-positive follicles. Hormone measurements also revealed that serum follicle-stimulating hormone concentration was significantly altered in taxane-exposed daughters, with the ratio of luteinizing hormone to follicle-stimulating hormone significantly elevated, specifically after paclitaxel exposure, coincident with the inability of these animals to properly respond to ovarian stimulation. Breeding studies over the course of a year also suggest that these taxane-exposed mice are fertile, although the duration of their fertility is shortened and they produce significantly fewer litters. Finally, ovarian effects are apparent in granddaughters of mice treated with docetaxel, suggesting persistent and multigenerational effects of taxane exposure.

CONCLUSION(S)

Our studies demonstrate that in utero exposure to taxane-based therapy during late gestation has a significant effect on the long-term reproductive health of exposed daughters (as well as their daughters) and will be instrumental in helping clinicians better understand which chemotherapies for maternal malignancy are least detrimental to a developing fetus.

The role of nitric oxide in small intestine differs between a single and a consecutive administration of methotrexate to rats

The role of nitric oxide (NO) on intestinal mucosal injury induced by single or consecutive administration of methotrexate was investigated in a rodent model. Rats received methotrexate intraperitoneally either as a single administration (50 mg/kg) or as a consecutive administration (12.5 mg/kg/day) for 4 days. N^G-nitro-l-arginine methyl ester (L-NAME) was given subcutaneously to inhibit NO synthase (NOS). Ninety-six hours after the first administration of methotrexate, ileal tissues were collected for analysis. Consecutive administration of methotrexate led to decreased body weight and reduced intake of food and water, which were further worsened by L-NAME. Although a slight mucosal injury resulted from single administration of methotrexate, L-NAME had almost no effect. Consecutive administration of methotrexate caused a significant mucosal injury, which was further worsened by L-NAME. Consecutive, but not single, administration of methotrexate induced mRNA expression of inflammatory cytokines in ileal tissue. Consecutive administration of methotrexate significantly induced constitutive NOS expression in ileal tissue. These results suggest that consecutive administration, rather than single administration, of methotrexate aggravates mucosal injury. Potentiation of constitutive NOS expression by consecutive administration might be one of the main reason to antagonize the intestinal mucosal injury as well as lead to a reduction in rat quality of life.

Mitochondrial oxidative stress-induced brain and hippocampus apoptosis decrease through modulation of caspase activity, Ca2+ influx and inflammatory cytokine molecular pathways in the docetaxel-treated mice by melatonin and selenium treatments

Docetaxel (DOCE) is widely used to treat several types of glioblastoma. Adverse effects DOCE seriously limit its clinical use in several tissues. Its side effects on brain cortex and hippocampus have not been clarified yet. Limited data indicated a protective effect of melatonin (MLT) and selenium (SELEN) on DOCE-induced apoptosis, Ca²⁺ influx and mitochondrial reactive oxygen species (ROS) in several tissues except brain and hippocampus. The purpose of this study is to discover the protective effect of MLT and SELEN on DOCE-induced brain and hippocampus oxidative toxicity in mice. MLT and SELEN pretreatments significantly ameliorated acute DOCE-induced mitochondrial ROS production in the hippocampus and brain tissues by reducing levels of lipid peroxidation, intracellular ROS production and mitochondrial membrane depolarization, while increasing levels of total antioxidant status, glutathione, glutathione peroxidase, MLT, α-tocopherol, γ-tocopherol, vitamin A, vitamin C and β-carotene in the tissues. Furthermore, MLT and SELEN pretreatments increased cell viability and TRPM2 channel activation in the hippocampus and brain followed by decreased activations of TNF-α, IL-1β, IL-6, and caspase -3 and - 9, suggesting a suppression of calcium ion influx, apoptosis and inflammation responses. However, modulator role of SELEN on the values in the tissues is more significant than in the MLT treatment. MLT and SELEN prevent DOCE-induced hippocampus and brain injury by inhibiting mitochondrial ROS and cellular apoptosis through regulating caspase -3 and - 9 activation signaling pathways. MLT and SELEN may serve as potential therapeutic targets against DOCE-induced toxicity in the hippocampus and brain.

Effects of a histamine H4 receptor antagonist on cisplatin-induced anorexia in mice

Cancer chemotherapy often induces gastrointestinal symptoms such as anorexia, nausea, and vomiting. Antiemetic agents are effective in inhibiting nausea and vomiting, but patients still experience anorexia. We previously reported that chemotherapeutic agent-induced anorexia is associated with an increase of inflammatory cytokines. Other studies also reported that antagonism of the histamine H₄ receptor is anti-inflammatory. In this study, we investigated the involvement of the H₄ receptor in the development of chemotherapy-induced anorexia in mice. Cisplatin-induced anorexia occurred within 24 h of its administration and continued for 3 days. The early phase (day 1), but not the delayed phase (days 2 and 3), of anorexia was inhibited by the daily injection of a 5-HT₃ receptor antagonist (granisetron). However, a corticosteroid (dexamethasone) or selective H₄ receptor antagonist (JNJ7777120) abolished the delayed phases of anorexia. Cisplatin significantly increased TNF-α mRNA expression in the hypothalamus and spleen, and the period of expression increase paralleled the onset period of anorexia. In addition, pretreatment with JNJ7777120 completely inhibited the increased expression. These results suggest that TNF-α mRNA expression via H₄ receptors may contribute to the development of cisplatin-induced anorexia, and that H₄ receptor antagonists are potentially useful treatments.

Smart pH-sensitive nanoassemblies with cleavable PEGylation for tumor targeted drug delivery

A new acidly sensitive PEGylated polyethylenimine linked by Schiff base (PEG-s-PEI) was designed to render pH-sensitive PEGylation nanoassemblies through multiple interactions with indomethacin and docetaxel (DTX). DTX nanoassemblies driven by PEG-s-PEI thus formulated exhibited an excellent pH-sensitivity PEGylation cleavage performance at extracellular pH of tumor microenvironment, compared to normal tissues, thereby long circulated in blood but were highly phagocytosed by tumor cells. Consequently, this smart pH-sensitive PEGylation cleavage provided an efficient strategy to target tumor microenvironment, in turn afforded superior therapeutic outcome in anti-tumor activity.

POMC maintains tumor-initiating properties of tumor tissue-derived long-term-cultured breast cancer stem cells

The identification and understanding of the molecular network of cancer stem cells (CSCs) have had a profound impact on our view of carcinogenesis and treatment strategy. Unfortunately, a major problem is that serial passages of CSCs from clinical solid tumor specimens currently are not available in any lab, and thus, reported data are difficult to confirm and intensively interrogated. Here, we have generated two tumor tissue-derived breast CSC (BCSC) lines that showed prolonged maintenance over 20 serial passages in vitro, while retaining their tumor-initiating biological properties. We then deciphered the intrinsic mechanism using analyses of mRNA expression array profiles. It has been determined that pro-opiomelanocortin (POMC) is closely related with protein phosphorylation mediated by G-protein-coupled estrogen receptor (GPER) in BCSC. Following, knockdown of POMC inhibits properties of mammosphere formation, CD44⁺ CD24^- population, CD44 expression, and clonogenicity ability in BCSC. We found that inhibition of POMC attenuates phosphorylation of AKT2 and GSK3β in BCSC. Further in vivo investigations demonstrated that POMC interference regulates proliferation of BCSC-bearing tumors. Combination of the clinical results that POMC positive expression is frequently upregulated in human breast cancer and POMC positivity correlated with a poor prognosis, POMC is a potential therapeutic target for BCSC. In conclusion, we have successfully established two long-term-cultured BCSC from clinical specimens. We further indicated that POMC acts as a potential therapeutic target and prognostic marker for future treatment of BCSC.

Involvement of substance P in the development of cisplatin-induced acute and delayed pica in rats

BACKGROUND AND PURPOSE

Although substance P (SP) and neurokinin NK1 receptors have been reported to be involved in cisplatin-induced acute and delayed emesis, their precise roles remain unclear. Pica, the consumption of non-nutrient materials such as kaolin in rats, can be used as a model of nausea in humans. We investigated the time-dependent changes in cisplatin-induced pica and the involvement of SP and NK1 receptors in this behaviour.

EXPERIMENTAL APPROACH

Rats were administered cisplatin with or without a daily injection of a 5-HT3 receptor antagonist (granisetron) or an NK1 receptor antagonist (aprepitant), and kaolin intake was then monitored for 5 days. The effects of granisetron on the cisplatin-induced expression of preprotachykinin-A (PPT-A) mRNA, which encodes mainly for SP, and on SP release in the medulla, measured by in vivo brain microdialysis, were also investigated.

KEY RESULTS

Cisplatin induced pica within 8 h of its administration that continued for 5 days. Granisetron inhibited the acute phase (day 1), but not the delayed phase (days 2-5), of pica, whereas aprepitant abolished both phases. Within 24 h of the injection of cisplatin, PPT-A mRNA expression and SP release in the medulla were significantly increased; these findings lasted during the observation period and were inhibited by granisetron for up to 24 h.

CONCLUSIONS AND IMPLICATIONS

The profiles of cisplatin-induced pica in rats are similar to clinical findings for cisplatin-induced emesis in humans, and we showed that SP production in the medulla and activation of NK1 receptors are involved in this cisplatin-induced pica.

Comparison of pharmacological and genetic inhibition of cyclooxygenase-2: effects on adult neurogenesis in the hippocampal dentate gyrus

Inducible cyclooxygenase-2 (COX-2) has received much attention because of its role in neuro-inflammation and synaptic plasticity. Even though COX-2 levels are high in healthy animals, the function of this factor in adult neurogenesis has not been clearly demonstrated. Therefore, we performed the present study to compare the effects of pharmacological and genetic inhibition of COX-2 on adult hippocampal neurogenesis. Physiological saline or the same volume containing celecoxib was administered perorally every day for 5 weeks using a feeding needle. Compared to the control, pharmacological and genetic inhibition of COX-2 reduced the appearance of nestin-immunoreactive neural stem cells, Ki67-positive nuclei, and doublecortin-immunoreactive neuroblasts in the dentate gyrus. In addition, a decrease in phosphorylated cAMP response element binding protein (pCREB) at Ser133 was observed. Compared to pharmacological inhibition, genetic inhibition of COX-2 resulted in significant reduction of neural stem cells, cell proliferation, and neuroblast differentiation as well as pCREB levels. These results suggest that COX-2 is part of the molecular machinery that regulates neural stem cells, cell proliferation, and neuroblast differentiation during adult hippocampal neurogenesis via pCREB. Additionally, genetic inhibition of COX-2 strongly reduced neural stem cell populations, cell proliferation, and neuroblast differentiation in the dentate gyrus compared to pharmacological inhibition.