目的：研究微小RNA Let-7a（miRNA Let-7a）在人乳头状瘤病毒（HPV）阴性组、HPV阳性组宫颈组织中的差异性表达，初步探讨其在HPV诱导子宫颈鳞状细胞癌的发生、发展过程中的作用。方法：通过HPV分型检测将宫颈脱落细胞及子宫颈活检样本分为HPV阴性组、低危HPV感染组、高危HPV感染组，结合病理学活检将高危HPV感染组分为慢性子宫颈炎组、低级别鳞状上皮内病变（LSIL）组、高级别鳞状上皮内病变（HSIL）组及子宫颈鳞状细胞癌组，用RT-PCR法对各组间miRNA Let-7a表达水平进行定量及差异性分析。结果：宫颈脱落细胞中miRNA Let-7a表达水平在HPV感染组显著低于HPV阴性组（P<0.01），而高危与低危间差异无统计学意义；组织活检样本中miRNA Let-7a表达水平在鳞状上皮内病变及鳞状细胞癌中显著下降（P<0.01），而鳞状上皮内病变与鳞状细胞癌组间差异无统计学意义。结论：HPV感染能显著降低子宫颈上皮细胞中miRNA Let-7a表达水平；且在HPV感染的组织学样本中，鳞状上皮内病变及鳞状细胞癌组中miRNA Let-7a水平显著低于炎性对照组。提示miRNA Let-7a水平下降是HPV介导的子宫颈鳞状细胞癌的发病机制之一。

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