document: the morbidity of breast cancer is gradually increasing , and a growing number of young people are now at risk for this disease . in china , 
   breast cancer continues to be the leading cause of death among women . with the improvement in diagnosis and development of drugs and radiotherapy technology 
   . therefore , early detection of the tumor and accurate analysis of molecular biology characteristics are still of great importance . 
   microrna ( mirna ) is a non - coding protein and single - stranded small rna . 
   it mainly inhibits translation or induces the degradation of some related mrnas through target mrna recognition , leading to changes in objective mrna at the protein expression level . 
   recent studies showed that some mirnas have functions similar to that of oncogenes or anti - oncogenes , which may play an important role in the invasion and development of breast cancer . 
   mir-125a , mir-206 , and mir-145 are similar to anti - oncogenes , and they are related to the occurrence of tumors . 
   thus , mir-206 plays a key role in adjustment during breast cancer proliferation . according to the research of scott and gk , mir-125a can affect the protein levels of her-2 and her-3 , thereby inhibiting the metastatic and invasive abilities of breast cancer cells . 
   moreover , lee   showed that mir-145 expression increases after mir-145 precursors transfect breast cancer cell lines , but can dose - dependently inhibit cell growth . mir-21 and mir-10b are similar to oncogenes , and related to the invasion and metastasis of tumors . in vitro and in vivo experiments showed that eliminating mir-21 gene fragments can inhibit the proliferation and invasion of mcf-7 and mda - mb-231 cells . in the 4t1 rat breast tumor metastasis model , mir-10b can effectively inhibit the metastasis of malignant breast cancer cells with high specificity . 
   the possible mechanism for this effect may be the inhibition of the entry of 4ti tumor cells into blood vessels . 
   however , the specific roles of mir-21 and mir-10b in the occurrence and development of breast cancer remain unclear . 
   the expression of mir-21 , mir-10b , mir-125a , mir-206 , and mir-145 in breast cancer tissues and para - carcinoma tissues was examined . 
   the expression of estrogen receptor ( er ) and progesterone receptor ( pr ) in breast cancer was analyzed by immunohistochemistry , whereas that of her-2 and topoisomerase 2a ( top 2a ) was analyzed by fluorescence in situ hybridization ( fish ) . 
   the relationship between the expression levels of mirnas and breast cancer clinical pathology was analyzed . 
   thus , this research aimed to investigate the function of mirnas in the invasion and development of breast cancer . 
   cancer tissues were obtained from these patients , who were pathologically confirmed to have invasive ductal carcinoma from january 1 2013 to december 1 2013 in the tumor hospital of the second affiliated hospital of xjtu . 
   all patients were female , with an age range of 4262 years ( mean age , 51 years ) . 
   these patients underwent modified radical mastectomy or reserved radical mastectomy , and had complete clinical pathology data . 
   the diameter of tumors ranged from 1.6 cm to 4.5 cm ( mean diameter , 2.2 cm ) . 
   one sample was cancer tissues , and the other sample was para - carcinoma normal gland tissues , which were more than 3 cm away from cancer tissues . 
   the samples were immediately flushed with 0.9% rna- and enzyme - free nacl , rapidly immersed in rna enzyme inhibitor , and incubated at 4c overnight . 
   the protective liquid was removed from the samples , which were stored in a refrigerator at 80c . 
   the patients were not treated before the operation , and neither neoadjuvant chemotherapy nor endocrine therapy was conducted . based on histological classification by the who ( 2003 ) standards , 
   m - mlv reverse transcriptase , rna enzyme inhibitor , oligo dt , dntps , kod - plus , and sybr mastermix were obtained from takara ( japan ) , and primers were from shanghai shenggong company ( china ) . 
   breast cancer her-2 , neu ( 17q12 ) , top 2a ( 17q21 ) , and csp 17 multicolor detection kits were purchased from guangzhou biping medical technology company . 
   total rna ( 500 ng ) was used for rt by mirna stem - loop rt primers . 
   the reaction was conducted in a 10-l system at the following reaction conditions : 16c for 30 min , 42c for 15 min , and 85c for 5 s. real - time qpcr was performed with a 20-l reaction system . 
   the mirna reaction detection system included 1 l of rt products , 1 sybr green i mastermix , 0.5 ixmol / l mirna - specific f - primer and 0.5 ixmol / l universal r - primer . 
   the conditions of immediate quantitative pcr were as follows : 95c for 10 min , followed by 40 cycles of 95c for 15 s and 60c for 1 min . 
   the circulation times in which real - time qrt - pcr reached the set - up threshold in every reaction tube ( ct data ) were recorded . according to some related studies , 
   the 2 method was used to express the gene expression of tumor tissues relative to that of the paired normal tissues . 
   moreover , ct=(ct mirna - ct u6 ) tumor  ( ct mirna - ct u6 ) was normal . 
   samples were fixed in formalin , embedded in paraffin , and sliced into 4-m - thick sections . 
   the results show positive expression of ep and er at 10% , and the cancer cell nucleus was brown . 
   samples were fixed in formalin , embedded in paraffin , and sliced into 4-m - thick sections . 
   sections were initially observed under the 40 objective with a suitable filter , and counted under the 100 objective . 
   the signals of gene - specific probe ( gsp ) her-2 ( red ) , gsp top 2a ( green ) , and centromeric probe ( csp ) 17 ( cyan ) were counted in 60 nuclei at the clear tumor areas . 
   the sum of signals of gsp her-2 , gsp top 2a , and csp 17 were recorded , and the data of gsp her-2/csp 17 and gsp top 2a / csp 17 were calculated . 
   the signals of her and top 2a were analyzed according to the following criteria : a ) the signal of gsp her-2 and top 2a ( red , green ) combined to bunches ; b ) gsp her-2 and top 2a / csp 17 ( red , green / cyan ) 2.2 and 2 ; c ) gsp her-2 and top 2a / csp 17 ( red , green / cyan ) < 1.8 and 0.8 ; and d ) gsp her-2 and top 2a / csp 17 ( red , green / cyan ) between 1.82.2 and 0.82.0 . if  a  or 
   if  d ,  new signal data should be counted in 20 other nuclei , or another researcher should recalculate the data . 
   researchers should indicate the consequence if the recalculated data were at the critical value . under situations with weak signal or high background , 
   signal judgment may be disturbed , so the experiment was repeated using another tissue slice . 
   differences in expression were analyzed by spss 13.0 . given the limited number of samples in this study , the data demonstrate an abnormal distribution . 
   all mirna expression data are shown as the median and interquartile range ( iqr ) . 
   the nonparametric wilcoxon test was used to rank matched - pair data , and the mann - whitney u test was used to compare data between the 2 groups . 
   cancer tissues were obtained from these patients , who were pathologically confirmed to have invasive ductal carcinoma from january 1 2013 to december 1 2013 in the tumor hospital of the second affiliated hospital of xjtu . 
   all patients were female , with an age range of 4262 years ( mean age , 51 years ) . 
   these patients underwent modified radical mastectomy or reserved radical mastectomy , and had complete clinical pathology data . 
   the diameter of tumors ranged from 1.6 cm to 4.5 cm ( mean diameter , 2.2 cm ) . 
   one sample was cancer tissues , and the other sample was para - carcinoma normal gland tissues , which were more than 3 cm away from cancer tissues . 
   the samples were immediately flushed with 0.9% rna- and enzyme - free nacl , rapidly immersed in rna enzyme inhibitor , and incubated at 4c overnight . 
   the protective liquid was removed from the samples , which were stored in a refrigerator at 80c . 
   the patients were not treated before the operation , and neither neoadjuvant chemotherapy nor endocrine therapy was conducted . based on histological classification by the who ( 2003 ) standards , 
   m - mlv reverse transcriptase , rna enzyme inhibitor , oligo dt , dntps , kod - plus , and sybr mastermix were obtained from takara ( japan ) , and primers were from shanghai shenggong company ( china ) . 
   breast cancer her-2 , neu ( 17q12 ) , top 2a ( 17q21 ) , and csp 17 multicolor detection kits were purchased from guangzhou biping medical technology company . 
   total rna ( 500 ng ) was used for rt by mirna stem - loop rt primers . 
   the reaction was conducted in a 10-l system at the following reaction conditions : 16c for 30 min , 42c for 15 min , and 85c for 5 s. real - time qpcr was performed with a 20-l reaction system . 
   the mirna reaction detection system included 1 l of rt products , 1 sybr green i mastermix , 0.5 ixmol / l mirna - specific f - primer and 0.5 ixmol / l universal r - primer . 
   the conditions of immediate quantitative pcr were as follows : 95c for 10 min , followed by 40 cycles of 95c for 15 s and 60c for 1 min . 
   the circulation times in which real - time qrt - pcr reached the set - up threshold in every reaction tube ( ct data ) were recorded . according to some related studies , 
   the 2 method was used to express the gene expression of tumor tissues relative to that of the paired normal tissues . 
   moreover , ct=(ct mirna - ct u6 ) tumor  ( ct mirna - ct u6 ) was normal . 
   samples were fixed in formalin , embedded in paraffin , and sliced into 4-m - thick sections . 
   the results show positive expression of ep and er at 10% , and the cancer cell nucleus was brown . 
   samples were fixed in formalin , embedded in paraffin , and sliced into 4-m - thick sections . 
   sections were initially observed under the 40 objective with a suitable filter , and counted under the 100 objective . 
   the signals of gene - specific probe ( gsp ) her-2 ( red ) , gsp top 2a ( green ) , and centromeric probe ( csp ) 17 ( cyan ) were counted in 60 nuclei at the clear tumor areas . 
   the sum of signals of gsp her-2 , gsp top 2a , and csp 17 were recorded , and the data of gsp her-2/csp 17 and gsp top 2a / csp 17 were calculated . 
   the signals of her and top 2a were analyzed according to the following criteria : a ) the signal of gsp her-2 and top 2a ( red , green ) combined to bunches ; b ) gsp her-2 and top 2a / csp 17 ( red , green / cyan ) 2.2 and 2 ; c ) gsp her-2 and top 2a / csp 17 ( red , green / cyan ) < 1.8 and 0.8 ; and d ) gsp her-2 and top 2a / csp 17 ( red , green / cyan ) between 1.82.2 and 0.82.0 . if  a  or 
   d ,  new signal data should be counted in 20 other nuclei , or another researcher should recalculate the data . 
   researchers should indicate the consequence if the recalculated data were at the critical value . under situations with weak signal or high background , 
   signal judgment may be disturbed , so the experiment was repeated using another tissue slice . 
   differences in expression were analyzed by spss 13.0 . given the limited number of samples in this study , the data demonstrate an abnormal distribution . all mirna expression data are shown as the median and interquartile range ( iqr ) . the nonparametric wilcoxon test was used to rank matched - pair data , and the mann - whitney u test was used to compare data between the 2 groups . 
   among the 35 samples , the relative quantity ( 2 ) of mir-125a was below 1 ( 80% ) in 28 cases and above 1 ( 20% ) in 7 cases . 
   the relative quantity ( 2 ) of mir-206 was below 1 ( 86% ) in 30 cases of breast cancer and above 1 ( 14% ) in 5 cases . 
   the relative quantity ( 2 ) of mir-145 was below 1 ( 60% ) in 21 cases of breast cancer and above 1 ( 40% ) in 14 cases . 
   the data ranged from 0.13 to 7.73 and the iqr was 0.511.72 . the median was 0.78 , which is 0.78 times that of normal tissue . 
   the relative quantity ( 2 ) of mir-21 was above 1 ( 94% ) in 33 cases of breast cancer and below 1 ( 6% ) in 2 cases . 
   the relative quantity ( 2 ) of mir-10b was above 1 ( 63% ) in 22 cases of breast cancer and below 1 ( 37% ) in 13 cases . 
   the difference was statistically significant ( p<0.05 ) . among the 35 patients , 16 cases ( 45.7% ) exhibited her-2 gene amplification , which was demonstrated as a red cluster or multiple red points , whereas 18 cases ( 51.4% ) exhibited top 2a gene amplification , which was demonstrated as a green cluster or multiple green points ( table 1 ) . 
   negative expression of her-2 and top 2a was observed in the 17 chromosome ( figure 1 ) . 
   the expression levels of mir-125a , mir-206 , and mir-145 in breast cancer tissues were all lower than those in para - carcinoma tissues 
   . low expression of mir-125a in the metastatic lymph node group and high negative expression of her-2 and top 2a in patients were unrelated to the tumor size , patient age , menstruation , negative er , and pr expression ( p<0.10 ) . 
   mir-206 was highly expressed in patients with small tumors , negative er , negative pr , and negative her-2 ( p<0.10 ) . 
   thus , mir-206 was irrelevant to patient age , menstruation , metastatic lymph node , and top 2a expression ( table 2 ) . 
   mir-145 was negatively correlated with the tumor size and lymph node metastasis ( p<0.05 ) , and had no correlation with patient age , menstruation , and pr expression . 
   however , mir-145 was correlated with negative er , negative her-2 , and negative top 2a ( p<0.05 ) ( table 3 ) . 
   the expression of mir-21 and mir-10b in breast cancer tissues was obviously higher than that in para - carcinoma tissues . 
   mir-21 exhibited high expression in older , postmenopausal patients with various symptoms , such as lymph node metastasis and positive her-2 ( p<0.10 ) , but it was not related to the tumor size and expression levels of top 2a , er , and pr . 
   the expression of mir-10b was related to the tumor size , lymph node metastasis , and positive top-2a ( p<0.05 ) , but it was not associated with age , menstruation , er , pr , and her-2 ( table 3 ) . 
   among the 35 samples , the relative quantity ( 2 ) of mir-125a was below 1 ( 80% ) in 28 cases and above 1 ( 20% ) in 7 cases . 
   the relative quantity ( 2 ) of mir-206 was below 1 ( 86% ) in 30 cases of breast cancer and above 1 ( 14% ) in 5 cases . 
   the relative quantity ( 2 ) of mir-145 was below 1 ( 60% ) in 21 cases of breast cancer and above 1 ( 40% ) in 14 cases . 
   the data ranged from 0.13 to 7.73 and the iqr was 0.511.72 . the median was 0.78 , which is 0.78 times that of normal tissue . 
   the relative quantity ( 2 ) of mir-21 was above 1 ( 94% ) in 33 cases of breast cancer and below 1 ( 6% ) in 2 cases . 
   the relative quantity ( 2 ) of mir-10b was above 1 ( 63% ) in 22 cases of breast cancer and below 1 ( 37% ) in 13 cases . 
   among the 35 patients , 16 cases ( 45.7% ) exhibited her-2 gene amplification , which was demonstrated as a red cluster or multiple red points , whereas 18 cases ( 51.4% ) exhibited top 2a gene amplification , which was demonstrated as a green cluster or multiple green points ( table 1 ) 
   . negative expression of her-2 and top 2a was observed in the 17 chromosome ( figure 1 ) . 
   the expression levels of mir-125a , mir-206 , and mir-145 in breast cancer tissues were all lower than those in para - carcinoma tissues . low expression of mir-125a in the metastatic lymph node group and high negative expression of her-2 and top 2a in patients were unrelated to the tumor size , patient age , menstruation , negative er , and pr expression ( p<0.10 ) . 
   mir-206 was highly expressed in patients with small tumors , negative er , negative pr , and negative her-2 ( p<0.10 ) . 
   thus , mir-206 was irrelevant to patient age , menstruation , metastatic lymph node , and top 2a expression ( table 2 ) . 
   mir-145 was negatively correlated with the tumor size and lymph node metastasis ( p<0.05 ) , and had no correlation with patient age , menstruation , and pr expression . 
   however , mir-145 was correlated with negative er , negative her-2 , and negative top 2a ( p<0.05 ) ( table 3 ) . 
   the expression of mir-21 and mir-10b in breast cancer tissues was obviously higher than that in para - carcinoma tissues . 
   mir-21 exhibited high expression in older , postmenopausal patients with various symptoms , such as lymph node metastasis and positive her-2 ( p<0.10 ) , but it was not related to the tumor size and expression levels of top 2a , er , and pr . 
   the expression of mir-10b was related to the tumor size , lymph node metastasis , and positive top-2a ( p<0.05 ) , but it was not associated with age , menstruation , er , pr , and her-2 ( table 3 ) . 
   recent studies have already proved that the expression of mirnas changes is closely related to various types of human cancer . 
   however , the functions of mirnas are complicated because they can effectively regulate and control hundreds of genes , including oncogenes and anti - oncogenes . 
   studies indicated that mir-125a ( has - mir-125a ) is located at chromosome 19q13.41 , including 2 mirnas that are in the same precursor ( mir-125a.5p and mir-125a.3p ) , and has the same origin as lin-4 in nematodes . 
   mir-125a can be detected as a phylogenetic mutation , which is associated with the occurrence of breast cancer . 
   mir-125a can also inhibit tumors by directly lowering the mrna and protein levels of some genes , such as erbb2 and rna binding protein hur . 
   mir-206 is located at human chromosome 6p12.2 , and is considered to be a type of mirna related to skeletal muscles and the myocardium . 
   it can boost muscle differentiation by lowering the p180 subunit of dna polymerase and muscle transcription factors ( e.g. , is13 and myor ) . 
   mir-206 can also inhibit the proliferation of breast cancer cells , mainly by lowering the mrna and protein expression levels of er and er co - regulatory proteins via the egf / mapk pathway [ lowering steroid acceptor nuclear co - activators ( e.g. , src-1 and src-3 ) and transcription factor gata-3 ] . 
   mir-206 can also act on the protein cx43 to inhibit the invasion and metastasis of cancer cells . 
   mir-206 can result in mutations at the rs6920648 locus , and is associated with the existence of breast cancer . 
   the expression of mir-145 decreases in many types of tumor tissues , including breast cancer , colon cancer , and lung cancer . 
   this phenomenon might be related to several factors , such as the location of mir-145 , ability of mir-145 to easily cause deficiency in tumor cells , and genetic changes in the receptor s surface . 
   similarly , mir-145 can inhibit hyperplasia in tumor cells by affecting target genes , such as c - myc , irs-1 , oct4 , sox2 , and klf4 . 
   mir-21 is an mirna located in the fra17b fragile area of chromosome 17q23.2 , and has an independent transcription unit . 
   moreover , mir-21 controls the expression of many anti - oncogenes , including tpm1 , programmed cell death 4 , maspin , and bcl-2 , to prompt the metastasis and hyperplasia of breast cancer cells . 
   mir-10b is located between the hoxd4 and hoxd8 genes of 2p31.1 , and its structure is 5-uacccuguagaaccgaauuugug-3. mir-10b is related to many types of tumors . 
   adjusting the twist - mir-10b - hoxd 10-rhoc pathway is the main mechanism by which mir-10b inhibits the metastasis of breast cancer cells . 
   mir-10b also facilitates the metastasis of breast cancer cells by regulating the expression of the target genes upar and syndecan-1 . 
   early diagnosis is essential to prevent and cure tumors . in this study , the relative transcript levels of mir-21 and mir-10b in patients tumor tissues were higher than those in para - carcinoma normal tissues . 
   by contrast , the relative transcript levels of mir-145 , mir-125a , and mir-206 in patients tumor tissues were apparently lower than those in para - carcinoma normal tissues . according to the literature [ 1214 ] , the relative transcript levels of mir-145 , mir-125a , and mir-206 in serum are also visibly abnormal compared with those in serum from healthy females . 
   therefore , these mirnas can be used as markers of breast cancer for early diagnosis . 
   our results show that mir-145 and breast cancer tumor size , as well as mir-145 and lymph node metastasis , was negatively correlated in 35 cases of breast cancer . 
   although mir-125a and mir-206 were expressed at low levels in the large mass group and lymph node metastasis group , statistical analysis showed no significant correlation between the expression of mir-125a and mir-206 and breast tumor size , as well as between the expression of mir-125a and mir-206 and lymph node metastasis . 
   we are currently further expanding the number of samples for analysis to determine the intrinsic correlations . 
   preliminary results show that mir-145 , mir-125a , and mir-206 were similar to tumor suppressor genes , and may be involved in the suppression of breast cancer invasion and metastasis ; these findings are consistent with those reported in the literature . 
   as indicated in the literature , mir-10b expression may indicate the invasion and development of breast cancer . 
   combined with the findings of lee , the results show that mir-21 may be correlated with old patients with lymph node metastasis . 
   hormone receptor - positive breast cancer , her-2-positive breast cancer , and triple - negative breast cancer ( tnbc ) ]  based on er , pr , and her-2 expression . 
   her-2-positive breast cancer is highly malignant , and can reappear and transfer easily . herceptin - targeted treatment has made significant progress for this type of cancer . 
   lee   showed that mir-21 is related to the metastasis of breast cancer lymph nodes and positive her-2 expression . 
   moreover , mir-21 is an independent prognostic factor of breast cancer . combined with cong s research 
   , the results showed that mir-21 is over - expressed in breast cancer cells resistant to trastuzumab , which causes the loss of pten expression . 
   a previous study   showed that mir-125a is negatively associated with her-2 , indicating that the her-2 gene may be under the regulation and control of mir-125a ; therefore , mir-125a can distinctly inhibit the expression of oncogenes her-2 and her-3 . 
   mir-125a expression is up - regulated when the hdac inhibitor entinostat is used to treat her-2-positive breast cancer cells , and has been shown to be an important mechanism of the functions of entinostat . 
   thus , mir-21 and mir-125a are significant to developing new anti - her-2 drugs and overcoming herceptin resistance in drugs . 
   tnbc is characterized by high malignancy , high possibility of reappearance and metastasis , and poor treatment methods . in this study , 
   mir-145 and mir-206 were found to be related to negative er and negative her-2 ( p<0.05 ) . 
   mir-145 was highly expressed in negative pr ( p>0.05 ) , whereas mir-206 was negatively correlated with negative pr ( p<0.10 ) . 
   showed that the metastasis of cancer cells could be inhibited by leading mir-145 and mir-206 into metastatic breast cancer cells . 
   mir-145 and mir-206 are expected to be the new target spots in tnbc treatment . besides inhibiting tnbc development , mir-206 can also inhibit positive er lines , and is considered as the switch of breast cancer when it is transferred to the base type from lumen - a . 
   top 2a codes dna topoisomerase ii , and is one of the components of the nuclear matrix . 
   top 2a can adjust the copy , transcription , recombination , and repair of dna , which is not only a hyperplasia index of tumor cells , but also a treatment target of anthracycline chemotherapy drugs . in breast cancer tissues , tumors with high expression of top 2a 
   this situation can be improved after using anthracycline alone or anthracycline combination chemotherapy . in this research , 
   mir-21 was found to be positively related to top 2a , whereas mir-125a and mir-145 were negatively associated with top 2a . 
   these findings show that mir-145 and mir-125a might inhibit the top 2a gene , and were connected with anthracycline drug resistance . therefore , mir-21 , mir-125a , and mir-145 may contribute to the chemotherapy effect of epirubicin , and are important in guiding the development of chemotherapy for breast cancer . 
   therefore , mir-125a , mir-206 , mir-145 , mir-21 , and mir-10b are highly expected to be novel tumor markers for the diagnosis and prognosis of breast cancer . mir-21 and mir-125a could contribute to the treatment of her-2-positive breast cancer cells , whereas mir-145 and mir-206 could accelerate the development of treatment methods for tnbc . 
   however , the detailed mechanism and whether these mirnas can be used as treatment targets in clinical applications should be verified in future investigations .
summary: backgroundthis study aimed to investigate the expression and significance of 5 types of mirnas in breast cancer to provide a theoretical and practical foundation for using these mirnas in the diagnosis and treatment of breast cancer , thereby improving medical services.material/methodsstem-loop real - time rt - pcr was used to detect the expression levels of mir-145 , mir-21 , mir-10b , mir-125a , and mir-206 in 35 cases of breast cancer and adjacent normal breast tissues , and to analyze the relationship of mirnas expression with clinicopathological features of breast cancer . 
   the expression levels of estrogen receptor ( er ) and progesterone receptor ( pr ) were examined by immunohistochemistry . 
   fluorescence in situ hybridization was used for the detection of her-2 and top 2a.resultsthe expression levels of mir-145 , mir-125a , and mir-206 in breast cancer were lower than those in adjacent normal tissues . 
   mir-145 was negatively correlated with tumor size , lymph node metastasis , er , her-2 , and top 2a ( p<0.05 ) , regardless of age , menstruation , and pr . 
   mir-125a was correlated with negative node status , negative her-2 status ( p<0.05 ) , whereas tumor size , age , menstruation , er , and pr were independent factors . 
   mir-206 expression was correlated with negative er status , negative pr status , and negative her-2 status ( p<0.05 ) , regardless of age , menstruation , lymph node metastasis , and top 2a . 
   mir-21 and mir-10b expression in breast cancer tissues was significantly higher than that in adjacent tissues ( p<0.05 ) . 
   mir-21 in post - menstrual patients with lymph node metastasis was highly expressed ( p<0.05 ) , and had no correlations with tumor size , er , pr , and top 2a expression . 
   mir-10b expression was positively correlated with breast cancer tumor size , lymph node metastasis , and top 2a status ( p<0.05 ) , but had no correlations with age , menstruation , er , pr , and her-2.conclusionsmir-145 , mir-21 , mir-10b , mir-125a , and mir-206 may play important roles in breast cancer development and invasion .