| objectiveTo observe the role of different MG132doses and different time inprevention and treatment of cancer cachexia through the animal model ofcancer cachexia, discuss the molecular mechanism,and provide new ideasfor the prevention of cancer cachexia.MethodsA mouse cancer cachexia model was induced by inoculating mousecolon cancer26cells into male BALB/c mice. Eighty-eight male BALB/cmice were divided into healthy control group (HC=8), cancer cachexiagroup (CC=16), MG132prevention with low concentration group (PL=8),middle concentration group (PM=16) and high concentration group (PH=8),MG132treatment with low concentration group (TL=8), middleconcentration group (TM=16) and high concentration group (TH=8). TheirBMI, diet intake and tumor volume were measured daily. Mice in preventionand treatment groups were intraperitoneally injected with MG132(0.01 mg/kg,0.1mg/kg and0.5mg/kg) on day5and12after inoculation ofcolon26. Eight mice in each group were killed on day19and their tumor, leftgastrocnemius muscle and epididymis adipose tissue were weighed. Theremaining8mice in CC group, PM group and TM groups received theoriginal treatment till their death and their survival time was recorded.Spontaneous physical activity of all groups mice were recorded bySpontaneous activity test video analysis system. Biochemical indicator weremeasured by automatic biochemistry analyzer. TNF-a and IL-6levels in theserum and gastrocnemius muscles were determined using a sandwich ELISA.Expression levels of mRNAs and proteins of IKBa, P65, MAFbx andMuRF1in gastrocnemius muscles and tumor of mice in various groups byRT-PCR and Western blot. Statistical analyses were performed using SPSS17.0.Results1general conditionThe tumor could be touched on the tumor-beating mice on5days afterinoculation Colon26.12days later, the body weight and spontaneousactivity significantly decreased, skin and fur became coarse， dark andgloomy of the CC, TL, TM and TH groups, which suggests these groupstumor-beating mice were in condition of cancer cachexia. But PM groupmice were into cachexia significantly delay. Compared with CC group,cachexia symptoms have improved in the prevention and treatment group, and PM group changes was the most obvious. There was no significantdifference in the diet intake among all the groups throughout the treatment(P>0.05).2Weight and tumor tissuesThere was no significant difference in the body weight among all thegroups before experiment (P>0.05). Compared with the HC group, theweight were reduced except the PM group(P<0.05), the non-tumor weight ofall the tumor-beating mice were reduced(P<0.05). Compared with the CCgroup, the non-tumor weight of the MG132prevention and treatment groupswere increased(P<0.05), the PM and TM group were the most increased inthe different dose groups, and the PM is better than TM group(P<0.05).Compared with the CC group, the tumor volume and tumor weight of theMG132prevention and treatment groups were reduce(P<0.05), the PH andTH group were the most increased in the different dose groups, and the PH isbetter than TH group(P<0.05), at the same time the PM is better than TMgroup(P<0.05).3Epididymal fat and gastrocnemius muscle tissueCompared with the HC group, the crosscutting area of gastrocnemiusand the weight of epididymal fat and gastrocnemius muscle weight weresignificantly reduced(P<0.05). Compared with the CC group, the aboveindicators of the MG132prevention and treatment groups wereincreased(P<0.05), the PM and TM group were the most increased in the different dose groups, and the PM is better than TM group(P<0.05).4Serum biochemical indexesCompared with the HC group, levels of Glu and ALB were reduced inall the non-tumor groups(P<0.05), level of TG were increased(P<0.05), levelof STP were reduced only in CC group(P<0.05). Compared with the CCgroup, levels of Glu and ALB of the MG132prevention and treatmentgroups were increased(P<0.05), level of TG were reduced(P<0.05)， thePM and TM group were the most change in the different dose groups. and thePM is better than TM group(P<0.05). level of TG of the MG132preventionand treatment groups were increased(P<0.05), but there was no significantdifference between PM and TM groups(P>0.05).5Activity and survival timeThere was no significant difference in the one hour spontaneous activitytotal distance among all the groups before experiment(P>0.05). Comparedwith the HC group, the distance of the CC group were reduced(P<0.05).Compared with the CC group, the distance of the MG132prevention andtreatment groups were increased(P<0.05), the PM and TM group were themost increased in the different dose groups. and the PM is better than TMgroup(P<0.05). Compared with the CC group, the survival time of theMG132prevention and treatment groups were prolong (27,36,32respectively)(P>0.05), the survival rate were increased (P>0.05), and thePM is better than TM group(P<0.05). 6The levels of TNF-a and IL-6in the serum and gastrocnemiusmusclesCompared with the HC group, the levels of TNF-a and IL-6of the CCgroup were increased(P<0.05). Compared with the CC group, the levels ofTNF-a and IL-6of the PM and TM group were reduced(P<0.05), and thePM is better than TM group(P<0.05).7Expression levels of mRNAs and proteins of IKBa, P65, MAFbx andMuRF1in gastrocnemius muscles and tumorCompared with HC group, the expression levels of mRNAs andproteins of IKBa in the CC group were significantly reduced(P<0.05), thelevels of P65, MAFbx and MuRF1were significantly increased(P<0.05).Compared with CC group, the levels of IKBa in gastrocnemius muscles ofthe PM and TM group were significantly increased(P<0.05), the levels ofP65, MAFbx and MuRF1were significantly reduced(P<0.05). Comparedwith CC group, the levels of IKBa in tumor of the PM and TM group weresignificantly increased(P<0.05), the levels of P65were significantlyreduced(P<0.05)，but there was no significant difference in the expressionlevels of MAFbx and MuRF1.Conclusion1A mouse cancer cachexia model was induced by inoculating mousecolon cancer26cells into male BALB/c mice, which is the classic animalmodel for cancer cachexia. 2MG132is an effective means to improve cancer cachexia syndrome.At the same time, the effect of early prevention is better.3MG132may attenuate cancer cachexia by reducing ubiquitindegradation of IκBα, blocking activation of NF-κB and hence upregulationof TNF-a and IL-6, inhibiting the downstream ubiquitin–proteasomepathways such as MuRF1and MAFbx. MG132could impede tumor growthby targeting NF-κB pathway, but ubiquitin–proteasome pathway seems notto contribute. |
PDF Full Text Request