Study Of Expression And Mechanism Of HIF-1α And MT In Papillary Thyroid Carcinoma

Objection: To investigate HIF-1α and metallothioneins (MTs) andpotential mechanism between them in papillary thyroid carcinoma (PTC)under hypoxic circumstances.Methods:129PTCs tissues were detected by immunohistochemistry.BcPAP and K1cells were cultured under hypoxic and normoxiccircumstances; expression of HIF-1α and MT were tested by Western blotand RT-PCR; invasion and migration ability were determined by Transwellassay. HIF-1α-siRNA, MT2A-siRNA, MT2A-pcDNA3.1andMT2A-pGL3-Basic plasmids were constructed successfully; BcPAP andK1cells were transfected with HIF-1α-siRNA, HIF-1α-pcDNA3andMT2A-pGL3-Basic; MT2A expression was detected by RT-PCR andluciferase report assay; BcPAP and K1cells were transfected withMT2A-siRNA and MT2A-pcDNA3.1; HIF-1α expression was measured byWestern blot.Results: HIF-1α and MT high expression rates were61.2%and45.7%in129PTC patients. The differences in HIF-1α and MT expression between PTCs and normal thyroid tissues were statistically significant(P<0.01). Meanwhile, high expression of HIF-1α and MT was correlatedwith high TNM stage (P<0.01) and lymph node metastasis(P<0.01).Furthermore, HIF-1α expression was positively correlated withMT (P<0.01). Under hypoxia, only protein expression level of HIF-1αincreased, while both RNA and protein expression of MT raised in BcPAPand K1cells. The potential of invasion and migration was promoted inhypoxic condition, compared to normoxic group (P<0.05). MT endogenousexpression and reporter gene activity decreased or increased in PTC celllines after being transfected with HIF-1α-siRNA, HIF-1α-pcDNA3orMT2A-pGL3-Basic plasmids. Likewise, HIF-1α protein expression levelwas down-regulated or up-regulated in PTC cell lines after being treatedwith MT2A-siRNA or MT2A-pcDNA3.1.Conclusion: In PTC patients, high expression of HIF-1α and MT wascorrelated with TNM stage and lymph node metastasis. Meanwhile, therewas a positive relation between them. Hypoxia could up-regulate theexpression of HIF-1α and MT in PTC cell lines, and reinforce their abilityof invasion and migration. In PTC cell lines, HIF-1α inhibition oroverexpression could decrease or increase MT2A endogenous mRNA leveland reporter gene activity. Likewise, MT2A inhibition or overexpressioncould down-regulate or up-regulate HIF-1α protein expression. To conclude,all above demonstrate that a possible interactive relation between HIF-1α and MT in PTC might exist.