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e14056 Background: Agomelatine is a melatonin receptor agonist (MT1 and MT2) and a 5-HT2C receptor antagonist. Melatonin is a lipophilic compound that is capable of binding to cell surface receptors, cytosolic sites (calmodulin), and directly to nuclear DNA binding sites (nuclear receptors RZR/RORα). Its direct antioxidant, antimitotic, antiestrogenic, prodifferentiating and antimetastatic effects have been well characterized. Nitric oxide (NO) is an inorganic free radical gas synthesized from L-arginine by a family of isoenzymes called NO synthases. Two of these are constitutively expressed and a third is inducible by immunological stimules. The NO released by the constitutive enzymes acts as an important signaling molecule in the cardiovascular and nervous systems and NO released by the inducible NO synthase (iNOS) is generated for long periods, by cells of the immune system among others, and has been shown to be cytostatic/cytotoxic for tumor cells and a variety of microorganisms. Methods: We have studied oncostatic/citostatic influence by ATP-TCA method of agomelatine and agomelatine + trastuzumab solution on the cellular cultures Her2/neu (+), MT1 and MT2 receptor (+) mammary ductal adenocarcinoma (17 cases). Data of ATP-TCA test in healthy patients breast’s cellular cultures with only trastuzumab were used as control. In parallel, we have studied expression of enzyme universal nitric oxide synthase (u-NOS) in cellular cultures of mammary ductal adenocarcinoma all three cells lines using Western blot method. The findings were compared to the data of u-NOS expression in healthy patients breast’s breast cellular cultures. Results: The study demonstrated that influence of citostatic effect of only agomelatine by ATP-TCA method are increased by 32.5% and citostatic effect of agomelatine + trastuzumab by ATP-TCA method also are increased by 45% in compared to control. Expression of universal nitric oxide synthase (u-NOS) is increased in case of mammary ductal adenocarcinoma by 14.2% in case only agomelatine and by 26.7% in case agomelatin + trastuzumab compared to control. Conclusions: Results of this research describe the positive role of agonists melatonin receptors (agomelatin) in the treatment previously treated and after progressed breast cancer (while this mechanism in details is unknown for us) and increased expression of NOS indicate the possibly augmentation sensitivity the cells lines for the citostatics medicines.

e12581 Background: According to WHO data, Breast Cancer is the most prevalent malignancy in women. The biological role of Melatonin in the etiology and pathogenesis of the tumour disease has already been approved by a number of research studies. The purpose of our investigation was the assessment of features of Melatonin receptor circadian expression in circulating tumour cells of breast cancer (CTCs). Methods: We observed 34 patients (aged 36-68) with breast cancer (various immunophenotypes). CTCs were separated from patients’ venous blood every third day, in 02:00-04:00 pm and in 02:00-04:00 am intervals. The cells were taken from each patient 4 times. On CTCs, MT1 – receptor expression was assessed using immunocytochemical method. Results: Results of the study revealed that Melatonin receptor expression in breast cancer patients is characterised by the noticable circadian rhythmics. MT1–receptor expression peak by CTCs was detected at 02:00-04:00 am i.e. at night. The less aggressive tumor the higher is the extent of the receptor expression (density). Respectively, in hormone dependent and Her2/neu (negative) tumors the highest expression of the MT1–receptor occurs in hormone dependent and Her2/neu(positive) tumors–medium expression and in triple negative breast Cancer (TNBC) cells–the lowest expression, while in some TNBC–circulating tumor cells MT1 receptor expression has not been detected at all. Conclusions: Hence, based on our the results, we can conclude that Melatonin as the expression of main biochemical marker receptors of bio-rhythms in breast cancer cells, has highly expressed chronobiological nature and directly correlates with histological types of tumor, that provides conditions for the development of new chronotherapeutic strategies in breast cancer treatment.

e12564 Background: Triple Negative Breast Cancer (ER-, PR-, Her2/neu-., TNBC) constitutes 15-18 per cent of all malignant breast cancers. It is characterized by aggressive course and high lethality. Methods: We assessed chronobiological features of 19 patients with TNBC (medium age group 34-71). We used data of Melatonin and Cortisol circadian secretions for assessment parameters. During the month, we took blood from patients on every third day, from 02:00-04:00 pm to 02:00-04:00 a.m time intervals. The control group was composed of 14 patients with breast cancer, histological type: ER/PR+ and Her2/neu-. Results: As the result of the research, meaningful differences have been revealed between the investigated and control group. In patients with TNBC, the medium day-time concentration of Melatonin during the day was 1.1 pg/ml (normal range - up to 20 pg/ml), while at night its level increased by 4.2 pg/ml. In the control group, the average day-time level was 5.7 pg/ml, and at night - 12.5 pg/ml. Regarding Cortisol, in the investigated group, in day-time hours its average concentration in blood was 2.1 μg/dl (normal tange - 2.5 - 11.9 μg/dl, at afternoon), while at night - 0.7 μg/dl (normal range < 1.8 μg/dl, at night). In the control group, at day-time, the average cortisol concentration was 4.095 μg/dl (normal range - 2.5 - 11.9 μg/dl, at afternoon), at night - 0.94 μg/dl (normal nange < 1.8 μg/dl, Night). Conclusions: The study results have showed significant biochemical differences between ER/PR+/ Her2/neu- and TNBC- patients. Reduction of circadian secretion of Melatonin, as a major biochemical marker, directly correlates with the degree of cancer aggression, as it is seen fom the study. Furthermore, in patients whose Melatonin concentration was critically low, ductal (CK5/6+ and/or EGFR+) and metaplastic (epidermal: CK5/6+, EGFR+, Ck14+, p63+) forms were histochemically detected, which are extremely aggressive subtypes of TNBC. Regarding Cortisol levels in patients with critically Melatonin level, the Cortisol concentration was at critically low margin as well, that is considered to be the additional chronobiological marker for the aggressive course and rapid progression of cancer.