Stimulatory Effect of Indolic Hormone on As2O3 Cytotoxicity in Breast Cancer Cells: NF-κB-dependent Mechanism of Action of Melatonin.

The advent of combination therapy unprecedentedly shifted the paradigm of cancer treatment by reconstructing the conventional protocols. By identifying the anti-tumoral activity for different natural products, recent interest has focused on inventing the combined- modality strategies to increase the cure rates of cancer, while reducing the toxic side effects of current intensive regimens. To evaluate whether melatonin, indolic hormone produced mainly by the pineal gland, could enhance the pro-apoptotic effect of arsenic trioxide (As2O3) in breast cancer, MCF-7 cells were treated with As2O3-plus- melatonin and then the survival, proliferative rate, caspase-3 activity, and mRNA expression level of anti- apoptosis target genes of NF-κB were investigated. Our results delineated that exposure of MCF-7 cells to As2O3 not only reduced the survival of the cells, but also induced a caspsase-3-dependent apoptotic cell death. Noteworthy, an enhanced induction of apoptosis was found using As2O3 in combination with melatonin. Moreover, RQ-PCR analysis revealed that the enhanced cytotoxic effect of As2O3 in the presence of melatonin is mediated, at least partly, through suppressing the expression of NF-κB anti-apoptotic target genes such as MCL-1, BCL-2, survivin, XIAP, and c-IAP1 in breast cancer cells. The resulting data showed that As2O3, either alone or in combination with melatonin, exerted significant cytotoxic effect against MCF-7 cells. However, further investigations are needed to provide valuable clues for expediting this combination as a therapeutic strategy for breast cancer.

Melatonin, an inhibitory agent in breast cancer.

BACKGROUND: The heterogeneous nature of breast cancer makes it one of the most challenging cancers to treat. Due to the stimulatory effect of estrogen in mammary cancer progression, anti-estrogenic agents like melatonin have found their way into breast cancer treatment. Further studies confirmed a reverse correlation between nocturnal melatonin levels and the development of mammary cancer. In this study we reviewed the molecular inhibitory effects of melatonin in breast cancer therapy. METHODS: To open access the articles, Google scholar and science direct were used as a motor search. We used from valid external and internal databases. To reach the search formula, we determined mean key words like breast cancer, melatonin, cell proliferation and death. To retrieval the related articles, we continuously search the articles from 1984 to 2015. The relevance and the quality of the 480 articles were screened; at least we selected 80 eligible articles about melatonin molecular mechanism in breast cancer. RESULT: The results showed that melatonin not only inhibits breast cancer cell growth, but also is capable of inhibiting angiogenesis, cancer cell invasion, and telomerase activity. Interestingly this hormone is able to induce apoptosis through the suppression or induction of a wide range of signaling pathways. Moreover, it seems that the concomitant administration of melatonin with other conventional chemotherapy agents had beneficial effects for patients with breast cancer, by alleviating unfavorable effects of those agents and enhancing their efficacy. CONCLUSION: The broad inhibitory effects of melatonin in breast cancer make it a promising agent and may add it to the list of potential drugs in treatment of this cancer.

Inhibitor of pan class-I PI3K induces differentially apoptotic pathways in acute leukemia cells: Shedding new light on NVP-BKM120 mechanism of action.

Complex interplay of intracellular signaling networks, spanning from the extracellular environment to the nucleus, orchestrate normal cell growth and survival. Dysregulation of such signals contributes to malignant transformation, thereby giving the cancer cells a survival advantage, but also could be exploited for new anticancer interventions. The aim of this study was to investigate the effects of pan class-I PI3K inhibitor NVP-BKM120 on two distinct acute leukemia cell lines, NB4 (with mutant p53) and Nalm-6 (with wild-type p53). Our data highlighted the efficacy of the inhibitor against APL and pre B ALL cell lines; however, we failed to find an obvious correlation between p53 status and the sensitivity of leukemic cells to NVP-BKM120. Real-time PCR analysis revealed a significant up-regulation of p53 target genes in Nalm-6 cells, indicating a p53-dependent mechanism involved in NVP-BKM120 cytotoxicity. On the other hand, cytotoxic effects in mutant p53-expressing NB4 cells seem to be mediated mostly by the inhibition of the PI3K/Akt/NF-κB axis. In conclusion, we suggest NVP-BKM120 induces apoptosis through p53-dependent and -independent mechanisms, indicating the potential application of the inhibitor in both wild-type and deficient p53-expressing leukemic cells.

Melatonin promotes ATO-induced apoptosis in MCF-7 cells: Proposing novel therapeutic potential for breast cancer.

Arsenic trioxide (ATO), a traditional Chinese medicine, has long been of biomedical interest and is largely used for treatment of a broad spectrum of cancers. Melatonin, a naturally occurring indoleamine synthesized in the pineal gland, has been considered as a biomarker for endocrine-dependent tumors, particularly breast cancer. An increasing number of studies indicate that melatonin could be an attractive candidate for combined therapy due to its anti-oxidant and cytotoxic activities. The aim of this study was to investigate the potentiating effect of melatonin on ATO-induced apoptosis in estrogen receptor (ER)-positive breast cancer cell line, MCF-7. Our data highlighted for the first time that pre-treating MCF-7 cells with physiological concentration of melatonin substantially augmented the cytotoxic effects of ATO as compared with either agent alone. Real-time PCR analysis revealed that apoptosis induction by the drugs combination was associated with increased p53 transcriptional activity followed by the elevated molecular ratio of Bax/Bcl-2. Moreover, induced p21, subsequent G1 cell cycle arrest and transcriptional suppression of survivin-mediated c-Myc and hTERT expression may contribute in the enhanced growth suppressive effect of ATO-plus-melatonin. Due to the safety profile of melatonin, our study suggests that using melatonin in combination with ATO might provide insight into a novel adjuvant therapy and may confer advantages for breast cancer treatment.

Effects of increasing durations of immobilization stress on plasma corticosterone level, learning and memory and hippocampal BDNF gene expression in rats.

Stress effects on learning and memory are widely recognized, but less agreement exists on whether they are positive or negative as well as on their neuronal and neuromolecular correlates. Stress involves expression of certain genes such as neurotrophin BDNF (brain derived neurotrophic factor), which is also involved in learning, but results are not consistent. Here effects of stress on memory and BDNF expression were studied using on adult male rats exposed to "immobilization stress" for various "short" durations, i.e., 1-h, 3-h, 5-h and "long-term" ones (2-h/day for 1 week). Learning and memory was measured using passive avoidance testing (STL=step-through-latency scores) as well as plasma corticosterone (CSt) levels and hippocampal BDNF gene expression. CSt increased in the 3-h and longer stressed groups but differences were significant in the 5-h and 1-week stressed subgroups. Three and 5-h of stress markedly and significantly (60-69%, p<0.01) decreased memory retention in the stressed animals, while 1-h of stress had no effect; prolonged stress (2-h daily for 1-week) increased memory significantly (33%, p<0.05). Hippocampal BDNF gene expression increased in the 1-h and 3-h stressed groups (44%, p<0.05 and 71%, p<0.01); but this parameter steadily declined in the 5-h stressed group (26%, p<0.05) and weeklong stressed group (6%, not significant). Statistical analysis revealed an apparent but significant negative correlation between changes in memory and those of BDNF gene expression, indicating that BDNF may possibly play a compensatory role, reversing deleterious effects of stress on hippocampal memory functions.

NMDA receptors are involved in Ginkgo extract-induced facilitation on memory retention of passive avoidance learning in rats.

Herbal therapies are commonly used to enhance memory and learning. Ginkgo biloba has shown to be one of the most popular herbs that is used to treat amnesia and retard age related memory deficits. Although, there have been several reports on the memory enhancing effects of Ginkgo, involvement of glutamatergic system that plays pivotal role in learning and memory has not been precisely assessed so far. The current study intended to investigate the effect of Ginkgo intake on amnesia while NMDA (N-methyl D-aspartic acid) receptors blocked by the administration of MK-801. The study used passive avoidance (PA) task to investigate the effect of chronic administration of Ginkgo extract (40 and 90 mg/kg; oral) on the memory span in male Wistar rats, suffering from MK-801-induced forgetfulness (0.06 and 0.1 mg/kg; i.p.). The results indicate that Ginkgo was able to remove MK-801-induced forgetfulness, indicating that Ginkgo can affect memory retention but not effect on passive avoidance acquisition, using pathways other than glutamatergic system as well. The results might indicate that Ginkgo extract can be effective in removing forgetfulness caused by inhibiting NMDA receptors from performing their activities.