Key words nasopharyngeal carcinoma; hour therapy; biological rhythms; circadian rhythm; clinical application

 The NPC is the southern part of the country, especially in Guangdong and a high incidence of malignant tumors. Radiation therapy for the treatment of nasopharyngeal carcinoma. But when newly diagnosed patients with advanced accounting about 70% after radiotherapy alone, more than half of the patients will relapse and (or) transfer, comprehensive treatment of advanced nasopharyngeal current research focus. In recent years, the study of tumor time rhythm, tumorigenesis, development, and the diagnosis and treatment of the new ideas and methods, and has become a hot spot within the field of cancer research at home and abroad. Hour chemotherapy has been applied in a variety of cancer treatment, and has achieved some success. Both basic and clinical research for nasopharyngeal hour therapy, have aroused the attention of many scholars.

    1 the nasopharyngeal hour therapy theoretical basis

    The 1.1 tumors hour therapy Overview

    Tumor hour therapy (tumor chronotherapy) is based on human circadian rhythms, and tumor cell growth characteristics in the circadian different time differences to develop the best treatment options to improve the efficacy and reduce side effects. 1960 began tumor hour therapy was due to the lack of direct evidence of the relationship between the tumor hour therapy and circadian rhythms, so research progress has been slow. But the past 10 years into the study of the “biological clock" become a hotspot of life science research. The study showed that: circadian rhythms not only affect the process of tumor development, but also closely related to the clinical prognosis, it is possible to become the new indicators of tumor treatment.

    1.2 biorhythms

    Biological rhythms: circadian rhythm (20 to 28h, ie circadian rhythm circadian rhythm); recent months rhythm 30 ± the 7d (circamensual rhythm); recent years rhythm of 12 ± 2 months (circannual rhythm). The present study was the largest circadian rhythm.

    The circadian clock gene (circadian clock genes) timing controller life activities, their activities so that the organs and tissues and cellular level, highly ordered life activities, collaborative, and presents a significant circadian rhythm. It is particularly important that they affect the cell cycle and apoptosis, neuroendocrine and immune function and the occurrence of malignant tumors, development, treatment and prognosis of various aspects of a close, to promote tumorigenesis circadian rhythm disorders, accelerated tumor progression, follow Chronobiology hour chemotherapy can increase efficacy. The in-depth study of the circadian rhythm gene provides a new perspective for understanding tumor, may become a new target for therapeutic intervention, the birth of a new model to follow when treating tumors.

    At the overall level, the mammalian the hypothalamic suprachiasmatic upper has the specialized nerve nuclei suprachiasmatic (suprachiasmatic nucleus, SCN), timing controller life activities, affecting the surrounding organs and tissues by the neurotransmitter, endocrine and humoral pathways control and regulate sleep and wakefulness, metabolic, endocrine, cell proliferation at all levels of the division and apoptosis, as well as immunization of life activities coordinated timing [2]. Surrounding organ tissue cells at the molecular level, SCN neurons, even in vitro culture passaging the cells are the same circadian clock genes, the basic mechanism of feedback regulation of the transcriptional and post-transcriptional level. The clock gene can be controlled by controlling its downstream bell gene (clock controlled genes, CCG) rendered rhythmic [4], one of the characteristics of the CCG containing E  box for CLOCK and BMAL1 binding. There are a number of studies [5] using DNA microarray technology on different points in time, each organ tissue transcripts found cell activity in almost every aspect of energy metabolism, cell proliferation and apoptosis, to ion channels, signal transduction and so there is a significant circadian rhythm and this rhythm coordinated, adaptable and forward-looking. [6] life activities.

    1.3 cancer cells circadian rhythm

    One of the malignant characteristics loss of controllability, disordered proliferation of cells, and this disorder is also inevitably reflected in the time dimension of the disorder. Especially affect the circadian clock genes and neuroendocrine, immune and cell cycle regulation closely associated with the cell cycle and apoptosis, it is closely related with the tumor.

    The circadian clock controls the cell cycle. Two periodic activities essentially associated with its mechanism of circadian rhythms and the cell cycle with the circadian rhythm gene discovery opened. At the molecular level, the circadian rhythm and the cell proliferation cycle two major regulatory pathway exists between the crossing point and common components [7]. There are a number of research groups the DNA array independently discovered WEE genes are common components of the two pathways [4]. Circadian rhythm genes controlling Wee 1, it presents circadian expression. Can activate in the day, when Bmall gene expression presents peak Wee 1, followed by Wee 1 cyclin Cdk 1 and Cdk 2 phosphorylation and inactivation of cyclin E and cyclin B1 were active, respectively, to promote cell cycle G to S, G, to the conversion of M, which can explain at the midnight of each day and night, the peak of the marked DNA synthesis of cyclin E and cell mitosis is always in phase on fixed companion. On the other hand, Per1 phase in the light of every day and night that the midpoint of the day reached its peak, so that the P53 upregulation, inhibition of cyclin B1 expression directly inhibit mitosis; in turn stimulates the generation of the P21 protein, inhibit Cdk2 and stimulates cyclin E expression, just reached the peak of DNA synthesis and day midpoint phenomena coincide [1,8  9].

    Lundkvist et al [10] found that the circadian rhythm gene mPer2 knockout mouse circadian rhythm disappeared, spontaneous tumor incidence significantly increase compared with wild-type mice, tumor incidence was significantly higher after gamma ray treatment, p53-mediated apoptosis. defective DNA repair, cell proliferation and tumor suppressor related genes of cyclin D1, cyclin A, Mdm  2 and Gadd45 c  myc expression, and thus the accumulation of DNA damage, apoptosis defects, and escape the cell cycle checkpoint, so c  myc expression the excessive increased, a significant increase in lymphoma incidence. In the overall level of anatomical damage in experimental animals the circadian rhythm regulating center SCN will result in tumor-bearing experimental animal tumor growth was significantly accelerated, survival was significantly reduced [11]; functional disrupt the circadian rhythm of the tumor-bearing experimental animals, such as giving continued lighting, or simulate jet lag or night work light mode, also observed similar results [12  13]. A disorder in the circadian rhythms of gene expression to promote cell proliferation related genes were up-regulated, and apoptosis-related genes suppressed. Therefore, the circadian rhythm homeostasis inhibit tumor growth.

    Various antitumor activity and immunomodulatory cytokines secretion majority of its physiological state in line with the laws of circadian rhythm similar to chemotherapy, and the hour, the clinical application of the Optional sometimes line may reach the maximum effect. The timing of administration of tumor necrosis factor, interleukin  2, interferon and erythropoietin, EPO and other biological agents, and efficacy was time-dependent law. Carrillo [14] bearing melanoma B16 of C57BL / 6 mice per 4h interval is divided into a set of different points in time be the same dose rHulFN  alphaA / D or rMulFN  the gamma results rHulFN  alpha A / D group minimum and the point of maximum activity HALO 12 ~ 16h and 0 ~ 4h, rMulFN  gamma group compared with the HALO 0 ~ 8h and 16h. rHulFN  alpha A / I) in the minimum effective point in time requires about 5 times the dose to be able to achieve the effect achieved by the same dose given in the most significant time points. rMulFN  gamma conclusions of similar efficacy of the most significant point in time is equivalent to 8.5 times the lowest point in time, that animal studies of interferon administration point in time to affect the inhibitory effect.

    Circadian rhythm disorders can cause a variety of diseases or the body’s physiological dysfunction, and is closely related with tumor. Therefore, the circadian rhythm steady state neuroendocrine and immune function, and cancer associated intermediary, is also an important measure. Vitamins (chronobiotics) “concept study, hoping to follow the circadian rhythm by correcting and adjusting circadian rhythm, making anti-cancer therapy to increase efficacy and reduce adverse reactions, enhance the quality of life. The current study as a manifestation of the central circadian rhythm hormone melatonin, melatonin, due to its broad regulatory role for the immune system, the neuroendocrine system, mental and physical links, as well as the immune system to become a whole, the impact significant tumor occurrence, development and metastasis. The past experimental animal tumor model studies support the melatonin inhibition of tumor cell proliferation, inhibit the role of EGFR and MAPK pathway differentiation and apoptosis [15]; recent study also found that inhibition of tumor cell uptake of linoleic acid and subsequent inhibition of proliferation; addition, a variety of immune cells with melatonin receptor immunomodulatory effects of melatonin. Although melatonin alone or in combination for the conclusion of clinical trials of cancer treatment varies, that the clinical trials that may previously not specifically focus on the timing of administration of the key variables, therefore, needs to be further verified. Some scholars even hope for its night illumination of breast cancer, colon cancer and other cancers in primary prevention preliminarily confirmed by epidemiological studies [16].

    The past time chemotherapy mechanism that, presented circadian rhythm associated with cytotoxic drug metabolizing enzymes such as thymidine synthase activity is the main reason, recent studies circadian rhythm gene mutation mice (Cry1-/  Cry2  /  double-knockout mice, Clock the mutant mice Bmall gene knockout mice) and wild mouse sensitivity comparison for toxility hour, found that Clock mutant mice, as well Bmall gene knockout mice, whenever you are sensitive to cyclophosphamide while Cry1  / Cry2  /  double knockout mice and vice versa, whenever showed resistance the inference the molecular nature of the chemotherapy drug toxicity hour difference Clock/Bmal1 transcription status, especially with the B cells in the circadian rhythm The different outcome of gene transcription functional status determines the survival and recovery after chemotherapy, the amendment of the past that only the mechanisms of circadian differences in pharmacokinetics [17].

    The study showed that human tumor cell mitotic index there is a big difference between the individual, but on a population level also hour rhythm, the highest point close to 3PM, the lowest point in nearly 3AM. Of DNA synthesis as a parameter, ovarian cancer DNA synthesis peak from 11:00 to 15:00 from 06:00 to 12:00 or 00:00 to 06:00, lung, head and neck cancer is 10:00. If you choose the right time of chemotherapy. To avoid normal tissue DNA synthesis peak selected tumor tissue DNA synthesis peak administration, the maximum extent to kill tumor cells while protecting the normal tissue, reduced toxicity. But there are a variety of cancer cells, the same cancer tissue can be speculated that the circadian rhythm in cancer cells than in normal cells complex. This shows that the understanding of each cancer patient’s circadian rhythm, can give full play to the role of anti-cancer drugs [18].

    2 nasopharyngeal hour therapy

    A number of studies have shown that nasopharyngeal induction chemotherapy compared with radiotherapy significantly improve tumor-free survival [19  20]. Traditional chemotherapy methods unsatisfactory efficacy, and adverse reactions. Drug hour chemotherapy given traditional drugs given specific drug or disease (patients) rhythm characteristics at a particular time, can significantly improve the efficacy.

    2.1 nasopharyngeal carcinoma cell biorhythms

    Sun Jian and other domestic scholars in the international arena for the first time reported a nasopharyngeal carcinoma tumor cell DNA synthesis time rhythm changes, confirmed human nasopharyngeal carcinoma in nude mice DNA synthesis was with the circadian rhythm changes, and this difference was statistically significance. Cosinor (cosine) analysis showed that the G1 and G2 / M phase cells change in line with the cosine curve S phase curve contrast more gentle, less than significant, nasopharyngeal carcinoma cell DNA synthesis in S phase peak at 11.5 HALO. Next, Sun Jian and other reports bearing human nasopharyngeal carcinoma in nude mice bone marrow cells DNA synthesis biological rhythms, confirmed the rhythm changes of human nasopharyngeal carcinoma in nude mice bone marrow cells DNA synthesis with alternating day and night was, and this difference was statistically significance. The Cosinor (cosine) analysis showed that G1, G2 / M phase cells 24h changes consistent with a cosine rhythm, the peak values ​​are located at 10.8 HALO and 1.8 HALO. S phase was not significant, DNA synthesis in bone marrow cells in S phase peak at 21.5 HALO. Nasopharyngeal carcinoma cells and bone marrow cell DNA synthesis, both the peak of the S phase of the 10h time difference, which is to select the appropriate time of administration so as to avoid marrow synthesized peak, concentrated to kill tumor cells provides an opportunity of S phase [ 21]

    2.2 of nasopharyngeal hour chemotherapy Experimental Study

    With the deepening of nasopharyngeal carcinoma cell biological rhythm research, scholars study confirmed the expression of mouse liver dihydropyrimidine dehydrogenase (DPD) showed significant circadian rhythm, the peak time is located about 16 HALO activity in mice [22]; human peripheral blood mononuclear cell DPD activity also changes in the circadian rhythm, with a peak at 22:00 ~ 02:00 [23]. Thymidylate synthase activity of circadian rhythm, the peak time in the light period, rhythm and DPD contrary. DPD is 5  Fu vivo metabolism of a starting enzyme and the rate-limiting enzyme of the toxicity of the active influence of the body 5  Fu. Both in healthy volunteers or cancer patients, from early morning to early as 10h the DPD activity compared with other time increased by 50%, exactly in the DPD activity peak of the health of the human body into the S phase of the bone marrow, small intestine, skin, and The proportion of the oral mucosa cells 24h cycle trough, resulting in 5  Fu best tolerated. Animal and human experiments have proved that given large doses of 5  Fu secretion peak period in DPD can reduce the toxicity improve efficacy. The activity of glutathione (GSH) and cisplatin toxicity foreign Levi research shows that GSH content showed a diurnal variation in each time phase differences are significant, and its peak phase in 13:00 [22]. The study provides a theoretical basis for nasopharyngeal hour chemotherapy.

    2.3 of nasopharyngeal hour chemotherapy clinical application

    Guo Ling et al [23] reported 30 patients with advanced nasopharyngeal regulation chemotherapy, the application of the Melodie multi-channel programming infusion pumps sinusoidal the curves form of time computer control to adjust the administration of induction chemotherapy group of 20 patients, 5  Fu 750 ~~ 850 mg / m2, 10:00 am from 22:00 until the second day of the administration, the concentration of the peak at 4:00 am, five days in a row; DDP 20mg/m2 administered from 10:00 ~ 22:00, the concentration of the peak for 16: 00, for five days in a row, line 2 courses, 5 weeks of radiotherapy after induction chemotherapy; chemotherapy alone group 10 cases, 5  Fu 600mg/m2, LV 200mg/m2, DDP 20mg/m2, for 5 consecutive days every 3 weeks repeat the same method of administration, and the peak time of induction chemotherapy group, LV 5  Fu method of administration, row 2 to 6 cycles of chemotherapy. Results: induction chemotherapy group rate (PR) of 100% after 2 cycles of chemotherapy; the end of the full course of CR of 95% (19/20); facts about the chemotherapy alone group and 80% (8/10) / 10% of the SD (1 / 10) /, PD 10% (1/10), the two sets of adverse reactions mainly Ⅲ ~ Ⅳ degree delayed platelet decrease in the incidence rate of 26.7% (8/30).

    Yang Xinglong et al [24] report 50 cases of patients with locally advanced or recurrent nasopharyngeal carcinoma were randomly divided into hour two of chemotherapy and conventional chemotherapy group. Chrono-chemotherapy group, 27 cases, 23 cases of conventional chemotherapy group. Hour chemotherapy group were treated with cisplatin (DDP) combined with intravenous infusion of 5-fluorouracil (5  Fu), DDP 20mg/m2, 10:00 to 22:00 administration  Fu 600mg/m2, 22:00 to the second day 10 : 00 end of the course of five days, after 16 days of intermittent; conventional chemotherapy medication and dose is the same as the former, but two kinds of drugs days 10:00 at the same time applications, two days after continuous 24h repeat treatments and the same period. Results: chrono-chemotherapy group complete remission rate and efficiency were 18.5% and 66.7%, respectively; complete response rate and efficiency of the conventional chemotherapy group were 8.7% and 39.1%, and the difference was statistically significant (P <0.05). Chrono-chemotherapy group of white blood cells, hemoglobin, platelet and bone marrow toxicity incidence was significantly lower than that of the conventional chemotherapy group (P <0.05).

    Goldwind et al [25] reported 60 patients with previously untreated patients with nasopharyngeal carcinoma, chrono-chemotherapy group of 30 patients were randomly divided into conventional chemotherapy group of 30 patients, all patients were treated with radiotherapy after two cycles of chemotherapy. Chrono-chemotherapy group, the BRAUN pump DDP 80mg/m2 (5ml / h, 3 days) on a daily 10:00 to 22:00;  Fu 750mg/m2 at 22:00 to the second day, 10:00, CF 200mg / m2, every day from 10:00 administered conventional infusion rate, once every three days, a cycle of 14 days, a total of 2 cycles; conventional chemotherapy dosage at the same time, Chen group, daily at 10:00, DDP and CF conventional infusion rate, 24h 5  Fu per day – continuous infusion, once every three days, a cycle of 14 days, for a total of 2 cycles. Results: chrono-chemotherapy group, CR was 28% (7/25) PR rate was 68% (17/25), the effective rate was 96% (24/25); conventional chemotherapy group CR rate was 15.4% (4 / 26), PR rate was 53.8% (14/26), the effective rate was 69.2% (18/26). Group response rate (CR + PR) difference was statistically significant (P <0.05), but the two groups CR rate was no significant difference (P> 0.05). Impact on immune function, chrono-chemotherapy group before and after treatment CD3, CD4, CD8, CD19, CD16 +56 there are significant differences in various indicators showed no significant difference before and after the treatment of the conventional chemotherapy group.

    3 Prospects

    In recent years, the time biomedical progress in basic research and cancer clinical tumor early diagnosis, treatment, and provide a new means and methods. There is no doubt that the application of chrono-chemotherapy compared with conventional chemotherapy, the patient’s efficiency and tolerability have great progress, and adapt along with the range of clinical practice and experience continue to expand. At the same time, the time pharmacology and cancer the time chemotherapy in development led some related technology advances, for example, a portable multi-channel time programmable infusion pump has been used in clinical, wrist actigraph controlled drug delivery technology have gradually been developed and Application. The wrist actigraph records of each patient the rest the  activities rhythm, and to develop the appropriate time chemotherapy. Hour the pump the  multi-channel programming infusion pump chemotherapy specific drugs also hour chemotherapy provides computer-control application of the pump, strictly controlled drug peak time, widely used in recent years, also in patients with nasopharyngeal carcinoma. Hour chemotherapy program implementation will be to promote the development and utilization of the old drug new clinical research and drug varieties, showing a more broad prospects, is also likely to bring about greater social and economic benefits. In short, the hour chemotherapy is a new treatment method, there are many issues that need to be further explored, broad application prospects.