| As one of the most important transcription factors, Stat5 a is widely expressed in lots of cell-types and plays a critical role in the development of reproductive system such as mammary gland through regulation of cell growth, proliferation, differentiation and apoptosis. A lot of studies evidenced that Stat5 a is also involved in reproductive cancer such as breast and prostate cancer. ?5 Stat5 a, is an N-terminal splice variant of hn RNA of FL Stat5 a, primarily found in human breast cancer cells,which is missing thirty amino acids of the N-terminus corresponding to the whole of exon 5. Primarily studies found higher expression of this variant in human breast cancer tissue than in the relatively normal tissue. We hypothese that the alternatively spliced form might play a pathological role in breast cancer due to the change of signal transduction pathways and biological characteristics of mammary gland cells.In present study, stable cell lines were established by infectting breast cancer cells(MCF-7) with lentivirus expression vector p LVX carrying FL(MCF7-FL) or ?5 Stat5 a c DNA(MCF7-Δ5),or vector p LCX only(MCF-Con), respectively, and by screening with puromycin resistance. Total RNA was isolated by Trizol reagent, and then, RNA-sequence was performed using Illumina Hi Seq TM 2500 high-throughput sequencing platform. Totally, 2588 human mi RNAs were examined in each sample, and the expression level for each mi RNA was standardized by using RPM and compared among the groups. Moreover, the possible new mi RNA and the second structure due to overexpression of FL or Δ5 Stat5 a in human breast cancer cells are also predicted.The sequencing data showed that both FL or Δ5 Stat5 a over-expression were able to induce the changes of mi RNA expression profile and abundance, and those changes mainly took place at chromosome 1, 3, 6, 7, 11 and 12.Of 2588 human mi RNAs, 595, 506 and 526 mi RNAs were detectable in MCF7-Con, MCF7-FL and MCF7-Δ5 respectively, with more than 60 % of the mi RNAs’ expression level between 1 and 100.11 and 21 mi RNAs were only detectable in MCF7-FL and MCF7-Δ5 respectively, Moreover, 17 and 17 mi RNAs were non-detectable in MCF7-FL, and in MCF7-Δ5, respectively.Compared with MCF7-Con, in MCF7-FL, the expression of 298 mi RNAs were altered, and, of them, 50 were altered significantly(Of them, 16 were up-regulated and 34 were down-regulated.). In MCF7-Δ5, the expression of 324 mi RNAs were different from MCF-7-Con, and of them, 50 were altered significantly with 13 up-regulated and 37 down-regulated. Furthermore, expression of 106 mi RNAs were different between MCF7-FL and MCF7-Δ5 with 103 signifcantly different(50 up-regulated and 53 down-regulated).Also, in the present study, 110, 91 and 105 possible novel mi RNAs were predicted in MCF7-Con, MCF7-FL and MCF7-Δ5 respectively. Of them, 27, 27, 25 were located at intergenic of gemome and possess similar structure with known mi RNA.The expression of mi RNA can be influened significantly by over-expression of FL Stat5 a and ?5 Stat5 a. Obviously, the 17 mi RNAs non-detecteable in MCF7-Δ5, while detectable in MCF7-FL and in MCF7-Con need to be further investigated. Especially, of them, hsa-mi R-873-3p and hsa-mi R-216b-5p(significantly difference vursus MCF7-Con), hsa-mi R-873-3p 、 mi R-486-5p 、 mi R-338-5p(significantly difference among three groups) raise our interesting and will be put in our further research list. Other mi RNAs including 50(including hsa-mi R-218-5p, hsa-mi R-34a-3p, hsa-mi R-155-5p) induced, as well as 53(such as hsa-mi R-199a-3p, hsa-mi R-335-5p, hsa-mi R-335-3p, and hsa-mi R-429) inhibited by overexpression of Δ5 Stat5 a need to be paid more attention. The above result indicates that ?5 Stat5 a may promote proliferation and migration of breast cancer cells by regulating the expression of these mi RNAs. On the other hand, micro RNA could, also, act as a regulator of Δ5 Stat5 a expression.Conclusively, the above results confirmed the importance of Δ5 Stat5 a in understanding the molecular mechanism underlying the occurrence and development of breast cancer. Lots of studies evidenced that mi RNA including hsa-mi R-199a-3p, hsa-mi R-335-5p, hsa-mi R-218-5p, hsa-mi R-34a-3p are involved in the onset and development of breast cancer. The exact relationship between mi RNA(such as hsa-mi R-3922-5p, hsa-mi R-5585-3p, hsa-mi R-6784-3p, hsa-mi R-659-5p and hsa-mi R-1261) and breast cancer, as well as the relationship between mi RNA and Δ5 Stat5 a are not clear yet. Further studies need to be performed. |
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