Sleep Disorder Facilitates Lung Cancer Progression Through Activating Medullary Serotoninergic Neurons

Objective: The lung is the most common cause of cancer death worldwide,and the most common histological subtype is non-small cell leukoencephalopathy,accounting for approximately 1.6 million deaths each year.There are many factors that promote the occurrence of lung cancer,which can be divided into two aspects: internal factors and external factors.The internal cause is mainly lung cancer caused by gene mutation,external factors include smoking,pollution,exposure to carcinogens,etc.Studies have shown that sleep disturbance can promote the progression of lung cancer in mice and increase the mortality of lung cancer mice.The regulation of peripheral organs by the central nervous system through the brain-gut axis or brain-lung axis is a research hotspot in recent years.Recent studies have shown that the activity of brainstem nuclei can significantly affect the progression of surrounding tumors;however,the underlying neural mechanisms by which sleep disturbance promotes lung cancer progression remain poorly understood.Therefore,it is particularly important to explore the neural mechanism by which sleep disturbance promotes the progression of lung cancer,which may provide new targets for neuro-immunotherapy of lung cancer.Methods: First,we determined the correlation between sleep and lung cancer progression through a clinical cross-sectional study.We used the Pittsburgh Sleep Quality Index(PSQI)to evaluate the sleep quality of 290 patients with lung cancer,and recorded the benign and malignant tumors.Secondly,we verified the effect of sleep disturbance on the growth of lung cancer in mice by establishing mouse circadian rhythm disorder and orthotopic lung cancer models.We then used retrograde tracing of pseudorabies virus to localize neural nuclei that are directly associated with the lung,and c-Fos immunofluorescent staining to localize activated neural nuclei in lung cancer-bearing mice.After determining the neural nuclei that have direct neural connections with the lung and are activated when lung cancer bears tumors,we use c-Fos and 5-HT immunofluorescence techniques to detect the activation status of 5-HT neurons in lung cancer and sleep disorders.Finally,brain stereotaxic injection and chemical genetic technology were used to regulate the activity of lung cancer-related neural nuclei,and their effects on the growth of lung cancer were observed.Results: By analyzing the PSQI clinical sleep quality questionnaire,we found that the poorer the sleep quality of lung cancer patients,the higher the proportion of malignant tumors;and in the tumor-bearing mouse model with circadian rhythm disorder,the lung tumor volume of the circadian rhythm disorder group was significantly larger than that of the control group.In the retrograde tracing experiment of pseudorabies virus,we located more than 16 neural nuclei that directly or indirectly innervate the lung in the whole brain.Through c-Fos immunofluorescence staining experiments,we found that the neuronal activity of Rostral ventromedial reticular nucleus/Rostral ventrolateral reticular nucleus(RVM/RVL)changed significantly when mice developed orthotopic lung cancer.Combining the results of retrograde tracing,we determined that RVM and RVL nuclei are the activated neural nuclei during the progression of lung cancer.Next,we found that the activation of 5-HT neurons in the RVM area was increased in sleep disorders compared with the control group;while the activation of 5-HT neurons in the RVM area was decreased in lung tumors compared with the control group.After further brain stereotaxic injection and chemical genetic regulation,it was found that specific activation of 5-HT neurons in the RVM region can promote the growth of lung cancer,while specific inhibition of 5-HT neurons in the RVM region can slow down the growth of lung cancer.Conclusion: The proportion of malignant lung tumors in patients with sleep disorders is significantly higher than that in patients with normal sleep;there is a direct neuromodulatory effect between the medullary RVM nuclei and the lungs;sleep disturbance can promote the progression of lung cancer by activating 5-HT neurons in the medullary RVM nuclei.Specific activation of 5-HT neurons in the RVM nuclei region by chemical genetic techniques can promote the growth of lung cancer,while specific inhibition of 5-HT neurons in this region can alleviate the growth of lung cancer.These results demonstrate that sleep disturbance can promote lung cancer progression by activating 5-HT neurons in the medullary RVM nuclei.