Triptolide Combined With Irradiation For The Treatment Of Nasopharyngeal Carcinoma Cells And Related Mechanism

OBJECTIVESNasopharyngeal carcinoma(NPC)is a highly prevalent head and neck squamous cell carcinoma in Southeast of Asia,due to its special anatomic location and tumor biological behavior,radiotherapy is the primary and only curative treatment for NPC.However,locally advanced NPC always invaded the wide scope of lesions and had the poor curative effect,in addition,owing to the frequency of local recurrence,the distant metastasis,radiotherapy had no effect on the distant metastasis,it affected the survival rate of patients seriously.Therefore,how to decrease the local invasion and distant metastasis become the main target of clinical treatment.At present,the combined radiation and chemotherapy is the main treatment of advanced NPC.However,the clinical curative effect on advanced NPC is very limited,so it is necessary to find a new strategy for treating advanced NPC.Triptolide(TPL)is a diterpenoid triepoxide derived from the Chinese herb Tripterygium wilfordii(Celastraceae).It has been reported to have various pharmacological effects,such as anti-inflammation,anti-oxidant,and anti-angiogenesis properties.It has been shown that TPL was a inhibition of NF-κB p65 and many researches revealed that it inhibited cancer by many ways,like suppressing angiogenesis and invasion of human anaplastic thyroid carcinoma cells via down-regulation of the NF-κB pathway,but there is no research about NPC.This study focused on triptolide plus ionizing radiation treating NPC in vitro and in vivo by the synergistic cytotoxicit.Meanwhile,we explore the molecular mechanism and provide new method and theory basis for prevention and control of NPC.METHODSHuman nasopharyngeal carcinoma(CNE-2)cells were cultured in vitro,and after being treated with different concentration of TPL and different doses of IR,or TPL plus IR in vitro,the cell proliferation,morphology,clonogenicity,apoptosis and related proteins were evalucated.Then,tumor gross evaluation,weight,volume and the weight of mice were observed afeter treatment of TPL,IR,or TPL plus IR in CNE cell xenograft mouse model.The effect of combined TPL and IR on NPC was analyzed.Meanwhile,the level of NF-κB related proteins in the tumor tissue was detected,whether TPL and IR can inhibit tumor growth by inhibiting p65 activation in tumor tissues,the possible mechanism for the treatment of NPC was studied.RESULTSThe results in vitro showed that TPL significantly inhibited the CNE-2 cell proliferation,clone formation,and promoted the apoptosis of cells,the combined treatment enhanced the inhibitory effect of CNE-2 cells.The results in vivo showed that the combination of TPL and IR significantly reduced the weight and volume of the tumor,without the obvious toxicity on nude mice.Theresults in vitro and in vivo indicated that the TPL promoted the expression of Bax,inhibited the expression of Bcl–2,VEGF and the phosphorylation of p65,without affecting other NF-κB related proteins.CONCLUSIONSTriptolide plus irradiation significantly inhibited the CNE cell proliferation,tumor growth and angiogenesis,and promoted the apoptosis of CNE cells by down-regulating p65 phosphorylation.In this research we found that triptolide plus ionizing radiation could be used as a potential treatment of NPC,it can promote apoptosis and inhibit angiogenesis by regulating p65 phosphorylation.TPL can be used as a kind of potential substitute of current chemotherapy,and combine with other methods on treating NPC.