A Related Study On Variations Of Intestinal Microbiota In Lung Cancer Patients Before And After Platinum-based Chemotherapy

Background and Objectives : Lung cancer is one of the most common malignant tumors.In recent years,the morbidity and mortality of lung cancer have ranked the top one among cancers,showing an increasing trend year by year.Early diagnosis is difficult,as a result,the majority of patients with lung cancer was diagnosed in an advanced stage,the two-drug regimen based on platinum is the standard first-line chemotherapy regimen.Clinically the most common adverse effects of platinum drugs are severe nausea,vomiting,loss of appetite,abdominal pain and other gastrointestinal adverse reactions,which not only increase the physical and mental suffering for patients and reduce their quality of life,but also limit the dosage and intensity of platinum drugs,thereby affecting the curative efficacy and prognosis.Studies have shown a close contact between gastrointestinal adverse reactions and intestinal microbiota.Currently little studies on the relationship between them have been reported.So have the studies on the relationship between intestinal microbiota and cancers except digestive cancer.Through the qualitative and quantitative study of the intestinal microbiota structure and specific bacterium in lung cancer patients before and after chemotherapy,as well as normol group,respectively,to explore the changes in lung cancer patients and after platinum-based chemotherapy.This would provide an assessment of host health status and the risk of lung cancer,as well as help to improve the platinum drug-induced gastrointestinal adverse reactions,from the perspective of microbial ecology.Methods:1.The collection of clinical samples: We screened 30 cases with lung cancer,who was treated with the two-drug regimen based on platinum at the Second Affiliated Hospital of Dalian Medical University from June to November of 2015,as the case group.,and Collected their fresh faeces before and after chemotherapy.Gender,age-matched 20 healthy people as a control group,their fresh faeces were collected meanwhile.Samples were placed in-80 ℃ refrigerator as soon as possible after collection.2.The intestinal bacterial genome DNA of the collected samples were extracted.3.By variable V3 region of 16 S r RNA gene,we got the bacterial cloned gene,then put it going on DGGE.The different bands selected from PCR-DGGE fingerprints was sequenced to confirm the categories after blasted with NCBI Gen Bank database.4.The amount of Lactobacillus and Bifidobacteria group was detected by RT-PCR in the control group as well as patients before and after chemotherapy.5.Results analysis:Quantity One was used for analysising the diversity and similarity cluster of DGGE profiles bands.SPSS19.0 was used for PCA and statistical data analysis.Measurement data was expressed as mean±standard deviation,the comparison between the two groups was made by the use of t-test,test level ɑ = 0.05(bilateral probabilistic method),P<0.05 means differences were statistically significant.Results:1.The intestinal microbiota changes of the lung cancer patients before chemotherapy compared with the healthy control group :(1)DGGE fingerprints showed that compared with the normal group,the diversity and abundance ofintestinal microbiota in lung cancer group significantly decreased(P <0.05).There are obvious differences between the two groups accroding to Cluster analysis and PCA.The copies of bacteria in per gram of feces in the two groups were lactobacilli(8.17±1.14;7.49±0.96),Bifidobacterium(9.16±0.84;7.73±0.71),lung cancer group was significantly lower than those in healthy controls(P < 0.05).2.Changes of intestinal microbiota in lung cancer patients after platinum-based chemotherapy:(1)The diversity and abundance of microbiota declined(P < 0.05)in cancer group after chemotherapy when compared with before chemotherapy.There existed significant differences in clustering before and after treatment.(2)Four strips which turned dim were cut off.Two of them were Ruminococcus sp.and Faecalibacterium sp.,whose homology respectively were 94% and 90%,the other two could not yet cultured in vitro.One strip with enhanced brightness might be Klebsiella pneumoniae with the homology of 99%.(3)The copies of bacteria in per gram of feces in the two groups were lactobacillus group(7.49±0.96;7.07±1.21),bifidobacteria group(7.73±0.71;6.64±1.03),the amounts of the two microbiota were both lower after chemotherapy(P < 0.05).(4)The difference of bifidobacterium between the two groups with or without gastrointestinal reactions was not statistically significant.So was lactobacillus group.Conclusions:1.There were significant differences in the structure of intestinal flora between lung cancer patients and healthy people,and both bifidobacteria and lactobacillus group significantly decreased.2.The imbalance of intestinal microbiota occured in lung cancer patients receiving platinum-based chemotherapy,with probiotics decreasing and conditional pathogenic bacteria increasing.The increase of intestinal Klebsiella pneumoniae may raise the risk of hematogenous infection.3.No correlation was found between gastrointestinal reactions and bifidobacteriaor lactobacillus group in lung cancer patients receiving platinum-based chemotherapy.