全新长链非编码RNA IRAIN在乳腺癌中的表达及意义

Expression and clinical significance of a novel long non-coding RNA IRAIN in breast cancer

目的探讨一种全新的长链非编码RNA IRAIN在正常乳腺组织及各分子亚型乳腺癌组织的表达水平及特点。方法半定量逆转录聚合酶链反应(RT-PCR)确定IRAIN mRNA是否表达于乳腺癌组织中;应用实时荧光定量逆转录聚合酶链反应(qRT-PCR)方法检测IRAIN mRNA和胰岛素样生长因子1受体(IGF-1R)mRNA在正常乳腺组织及不同分子亚型乳腺癌组织的表达水平及特点;应用链方向特异性RT-PCR(SSRTPCR)绘制IRAIN转录方向;用DNA测序方法分析冰冻人乳腺癌组织中IRAIN SNP位点(rs8034564)杂合状态及等位基因表达特点,明确该基因是否呈单等位印记表达。结果与正常乳腺组织相比,各分子亚型乳腺癌中IRAIN表达均降低,其中以三阴性乳腺癌降低最为明显,人表皮生长因子2(HER2)阳性型乳腺癌IRAIN表达也明显低于正常乳腺组织(P<0.05)。Luminal型同样低于正常乳腺组织,但无统计学意义(P>0.05)。而对后三者做两两比较,无统计学意义(P>0.05)。IGF-1R在预后最好的Luminal型中表达最高,与正常乳腺组织接近,而在预后差的TNB型和HER2阳性型表达明显低于正常乳腺组织及Luminal型(P<0.05)。对TNB型和HER2阳性型两者做比较,无统计学意义(P>0.05);IRAIN转录方向与IGF-1R mRNA的方向相反,是IGF-1R的反义长链非编码RNA;IRAIN在人乳腺癌组织中呈单等位基因表达,且呈单等位基因不均衡表达。结论 IRAIN是IGF-1R基因的反义长链非编码RNA,在人乳腺癌组织中呈单等位基因不均衡表达,可能作为抑癌基因,调控肿瘤细胞生长。

Objective Objectives To explore the expression and characteristics of a novel LncRNA-IRAIN illustrated in normal breast tissues and different breast cancer molecular subtypes. Methods IRAIN mRNA expression was confirmed in breast cancer tissue by semi quantitative reverse transcription polymerase chain reaction（ RT-PCR）. IRAIN mRNA and IGF-1R mRNA were tested for the expression level and features in normal breast tissue and different breast cancer molecular subtypes by quantitative real time polymerase chain reaction（ qRT-PCR）. IRAIN transcription orientations were mapped by strand-specific RT-PCR（ SSRT-PCR）. Heterozygous state and allele expression features of IRAIN SNP site（ rs8034564） were analyzed in frozen human breast cancer tissues with DNA sequencing approaches for confirming if the gene was monoallelic imprinting expressed.Results IRAIN expression was low in all molecular subtypes. Among them,the triple negative breast cancer became the most prominent in the reduction of IRAIN expression,and the HER2 over-expression subtype also dropped considerably compared with the normal group. The differences were significant. The expression of IRAIN in Luminal subtype was also lower than that of the normal,but there was no significant difference. In pairwise comparison of the last three group suggested no significant difference（ P〉0.05）. The expression of IGF-1R was the highest in Luminal subtype which had the best prognosis,and was close to that in the normal breast tissue,while in poor prognostic types such as TNB and HER2＋,the expression was significantly lower than that of the normal group and Luminal group（ P〈0.05）. The difference between TNB and HER2＋ subtype was not significant（ P〉0.05）. The transcription orientation of IRAIN was the opposite to that of IGF-1R mRNA. IRAIN was transcribed antisense to IGF-1R in breast cancers and was monoallelicly expressed in cancer tissues. However,it was interesting to note the expression of the ＂ A＂ allele was favored over the ＂ G＂ allele.Conclusions IRAIN is transcribed antisense to IGF-1R and monoallelicly expressed in breast cancer tissue,unequally. IRAIN could be treated as antioncogene to regulate the growth of tumor cells.