The Mechanisms Of Capaicin Suppressing The Metastasis And Dedifferentiation Of Thyroid Cancer Cells

Capsaicin is one of the major ingredients of red pepper,being responsible for the pungent flavor.Recently,capsaicin has attracted more and more attentions owing to its multiple biological activities on neuralgia and arthritis treatment.However,the anticancer effects of capsaicin against malignant neoplasm,especially on thyroid carcinoma,is not fully investigated.Our present study mainly investigated the metastatic inhibitory effect of capsaicin on papillary thyroid carcinoma BCPAP cells and follicular thyroid carcinoma FTC-133 cells.In addition,the differentiation-promotion effect on anaplastic thyroid carcinoma 8505C cells of capsaicin was investigated.Meanwhile,the underlined mechanisms will be discussed.Our results not only provide scientific proofs for the application of capsaicin in thyroid cancer therapy,but also give new prospects for further exploring the new therapeutic targets in thyroid cancer.Primarily,our results indicated that capsaicin?25-100?mol/L?could inhibit multiple steps of metastasis without affecting the cell viability of BCPAP cells.Capsaicin significantly suppressed the migration and invasion of BCPAP cells as well as its attachment.The protein levels of Snail1,Snai2 and Twist2,three critical EMT transcription factors?EMT-TFs?,dramatically declined by capsaicin treatment in a dose-dependent manner.Subsequently,the expression of downstream protein E-cadherin was up-regulated.Capsaicin also inhibited the expression of MMP-2 and MMP-9 significantly.TRPV1 is a specific receptor of capsaicin,being involved in various biological and physiological processes.When cells were pre-treated with capsazepin,a specific TRPV1 antagonist,or when TRPV1 was silenced using specific shRNA,the inhibitory effects of capsaicin on the metastasis of BCPAP cells were abrogated.Our results suggest that capsaicin,a distinctive agonist of TRPV1,exerted metastatic inhibition on papillary thyroid cancer BCPAP cells,indicating that modulation of TRPV1 activation remains a critical strategy for cancer treatment.In addition,capsaicin could also inhibit the migration and invasion of thyroid follicular cancer FTC-133 cells.We found that capsaicin decreased the transcriptional levels of Twist1and Snail by q-PCR assay,these results demonstrated that capsaicin reversed the process of EMT to a certain extent to inhibit the metastasis of FTC-133 cells.It was found that capsaicin could also inhibit the phosphorylation of CaMKII in a dose dependent manner.It is suggested that capsaicin reverses the EMT and suppresses the activation of CaMKII to inhibit the metastasis of FTC-133 cells.Furthermore,we investigated the effects and mechanisms of capsaicin on the re-differentiation of 8505C cells.MTT assay indicated that capsaicin had a significant cytotoxicity on 8505C cells.Capsaicin induced cell apoptosis in 8505C cells,which was evidenced by the results of PI/Hoechst 33342 staining,AnnexinV/PI assay and Western blot.To further investigate the mechanisms of apoptosis in 8505C cell induced by capsaicin,we found that capsaicin triggered cell re-differentiation of 8505C cells.The expressions of Nanog,SOX2 and Oct4A,three well-known stemness-associated genes,were down-regulated by capsaicin treatment accompanied with the upregulation of TTF-1,a thyroid transcription factor.Its downstream genes NIS and TPO,two thyroid specific genes which are responsible for normal thyroid functions were also upregulated by capsaicin.Meanwhile,capsaicin could enhance the ability of ¹³¹I uptake of 8505C cells.Above all,capsaicin induced re-differentiation of 8505C cells through suppressing the MAPK signaling pathway.In a summary,these results revealed that capsaicin reversed the progress of EMT,inhibited the migration and invasion of papillary thyroid cancer BCPAP cells and follicular thyroid carcinoma FTC-133 cells.Besides,capsaicin induced cell re-differentiation of anaplastic thyroid cancer 8505C cells through suppressing the MAPK signaling pathway,which restored the function of normal thyroid cells.Therefore,capsaicin possessed potential to become a novel strategy to treat metastatic papillary thyroid cancer or anaplastic thyroid cancer,which are two types of aggressive thyroid carcinamas.