colorectal cancer ( crc ) is one of the most commonly diagnosed cancers in the world , with over 600,000 deaths per year .
unfortunately , the morbidity of crc has been rapidly rising in asian countries in recent years .
however , the multiple known carcinogenic factors and complex genetic backgrounds make it difficult to estimate the key factor in crc progression . at the present time , the basic prognostic biomarker in crc is the clinicopathologic tumor staging , based on the tumor - node - metastasis ( tnm ) system . nevertheless , the tnm stage is not an ideal biomarker for crc outcomes .
patients at the same tnm stage may have different progressions and clinical outcomes due to their various genetic and epigenetic backgrounds .
therefore , it is necessary to identify sensitive and specific molecular biomarkers for crc clinical outcomes .
long non - coding rnas ( lncrnas ) transcribed by rna polymerase ii lack open reading frames ( orf ) longer than 200 nucleotides . although the functions of most lncrnas are unknown , more and more lncrnas are characterized and many of them are reported to regulate gene expression in the development and differentiation of diseases [ 811 ] .
for example , lncrna cche1 promotes cervical cancer cell proliferation , hnf1a - as1 regulates proliferation and metastasis in lung adenocarcinoma , and malat1 is associated with poor prognosis of glioma .
spry4-it1 is significantly increased in plasma samples of nsclc patients and can act as a biomarker in nsclc .
trpm2-as can act as a novel biomarker and therapeutic target in prostate cancer . in this study , we focused on lncrna spry4 intronic transcript 1 ( spry4-it1 ) , which is located within an intron of the spry4 gene .
spry4-it1 was previously reported to be up - regulated in melanoma , gastric cancer , breast cancer , and esophageal squamous cell carcinoma [ 1720 ] .
however , the effect of spry4-it1 in crc prognosis is unknown . in the present study ,
we applied different methods in analyzing the association between spry4-it1 expression and clinical features , aiming to determine the clinical influences of spry4-it1 in crc patients and to discover a reliable predictor for crc .
in this study , 106 crc patients confirmed by pathological and clinical diagnoses at the pla general hospital were enrolled from october 2008 to january 2014 .
this study was approved by the ethics committee of pla general hospital , and written consent was obtained from all the patients .
tumor and adjacent normal tissues were obtained from the crc patients before they received any chemotherapy or radiotherapy .
all the tissue samples were stored in liquid nitrogen until they were utilized . in order to observe the results of the surgery
, follow - up was performed every 3 months in the first 2 years and then every 6 months until the end of the study .
total rna was extracted from all the tissues using trizol reagent according to the manufacturers instructions .
the extracted rna was dissolved in diethyl pyrocarbonate ( depc)-water and then treated by dnase to remove dna .
the concentration of the total rna was detected by uv absorbance at 260 nm and 280 nm ( a260/a280 ) .
fluorescence quantitative real - time pcr ( qrt - pcr ) was used to assess the relative expression levels of spry4-it1 in pathologic and adjacent normal tissues of crc patients .
the complementary dna ( cdna ) temples enrolling in the qrt - pcr were from the primescript rt reagent kit ( takara , china ) .
the qrt - pcr was performed with sybr green assay ( takara , china ) .
student s t - test was used to estimate the different expression levels of spry4-it1 and the data are shown as mean  standard deviation ( sd ) .
the association between the clinical features and spry4-it expression was evaluated by chi - square method .
kaplan - meier method with log - rank test was applied to analyze the overall survival of the crc patients , and univariate and multivariate cox regression analysis were used to evaluate the prognostic value of spry4-it1 .
in this study , 106 crc patients confirmed by pathological and clinical diagnoses at the pla general hospital were enrolled from october 2008 to january 2014 .
this study was approved by the ethics committee of pla general hospital , and written consent was obtained from all the patients .
tumor and adjacent normal tissues were obtained from the crc patients before they received any chemotherapy or radiotherapy .
all the tissue samples were stored in liquid nitrogen until they were utilized . in order to observe the results of the surgery
, follow - up was performed every 3 months in the first 2 years and then every 6 months until the end of the study .
total rna was extracted from all the tissues using trizol reagent according to the manufacturers instructions .
the extracted rna was dissolved in diethyl pyrocarbonate ( depc)-water and then treated by dnase to remove dna .
the concentration of the total rna was detected by uv absorbance at 260 nm and 280 nm ( a260/a280 ) .
fluorescence quantitative real - time pcr ( qrt - pcr ) was used to assess the relative expression levels of spry4-it1 in pathologic and adjacent normal tissues of crc patients .
the complementary dna ( cdna ) temples enrolling in the qrt - pcr were from the primescript rt reagent kit ( takara , china ) .
the qrt - pcr was performed with sybr green assay ( takara , china ) .
statistical analysis was completed in spss 18.0 software . student s t - test was used to estimate the different expression levels of spry4-it1 and the data are shown as mean  standard deviation ( sd ) .
the association between the clinical features and spry4-it expression was evaluated by chi - square method .
kaplan - meier method with log - rank test was applied to analyze the overall survival of the crc patients , and univariate and multivariate cox regression analysis were used to evaluate the prognostic value of spry4-it1 .
the 106 crc patients enrolled in this study included 52 men and 54 women with an average age of 55.02 years old .
qrt - pcr was used to evaluate the relative expression of spry4-it1 in crc tissues and normal tissues .
the results indicated that the relative expression of spry4-it1 in pathologic tissues was significantly higher than that in the adjacent normal tissues ( p=0.000 , figure 1 ) . to evaluate the association between spry4-it1 expression and clinical features
, the crc patients were divided into high and low expression groups on the basis of their average expression of spry4-it1 .
the chi - square results are shown in table 2 , which shows that the expression levels of spry4-it1 were associated with the tumor size ( p=0.013 ) , the depth of invasion ( p=0.004 ) , lymph node metastasis ( p=0.017 ) , distant invasion ( p=0.012 ) , and tumor stage ( p=0.015 ) . however , there was not significant relationship between the expression levels and sex , age , tumor location , histological differentiation , venous invasion , or nerve invasion ( p>0.05 ) .
the results suggest that the expression level of spry4-it1 might be associated with the development of the crc .
overall survival analysis was conducted by kaplan - meier method , showing that the crc patients with high expression of spry4-it1 had low overall survival ( the average overall survival was 39.3 months ) , while the low expression patients had an average overall survival of 49.3 months ( figure 2 ) . in other words ,
differences between the 2 groups were significant ( log - rank test , p=0.016 ) . in this study , we used cox regression analysis to estimate the prognostic value of spry4-it1 .
the results of univariate analysis show that the levels of spry4-it1 were significantly associated with the poor prognosis in crc patients ( p=0.021 ) .
multivariate analysis suggests that spry4-it1 is an independent factor for crc prognosis ( hr=2.341 , 95% ci=1.1364.826 , p=0.021 ) .
the 106 crc patients enrolled in this study included 52 men and 54 women with an average age of 55.02 years old .
qrt - pcr was used to evaluate the relative expression of spry4-it1 in crc tissues and normal tissues .
the results indicated that the relative expression of spry4-it1 in pathologic tissues was significantly higher than that in the adjacent normal tissues ( p=0.000 , figure 1 ) .
to evaluate the association between spry4-it1 expression and clinical features , the crc patients were divided into high and low expression groups on the basis of their average expression of spry4-it1 .
the chi - square results are shown in table 2 , which shows that the expression levels of spry4-it1 were associated with the tumor size ( p=0.013 ) , the depth of invasion ( p=0.004 ) , lymph node metastasis ( p=0.017 ) , distant invasion ( p=0.012 ) , and tumor stage ( p=0.015 ) . however , there was not significant relationship between the expression levels and sex , age , tumor location , histological differentiation , venous invasion , or nerve invasion ( p>0.05 ) .
the results suggest that the expression level of spry4-it1 might be associated with the development of the crc .
overall survival analysis was conducted by kaplan - meier method , showing that the crc patients with high expression of spry4-it1 had low overall survival ( the average overall survival was 39.3 months ) , while the low expression patients had an average overall survival of 49.3 months ( figure 2 ) . in other words ,
differences between the 2 groups were significant ( log - rank test , p=0.016 ) .
in this study , we used cox regression analysis to estimate the prognostic value of spry4-it1 .
the results of univariate analysis show that the levels of spry4-it1 were significantly associated with the poor prognosis in crc patients ( p=0.021 ) .
multivariate analysis suggests that spry4-it1 is an independent factor for crc prognosis ( hr=2.341 , 95% ci=1.1364.826 , p=0.021 ) .
despite great progress in early diagnosis , surgical techniques , and chemotherapy , the prognosis of patients with crc is still unsatisfactory .
prognostic factors are helpful in determining the therapeutic regimen in cancers . due to the complex genetic background and epigenetic factors ,
there is still no highly sensitive and specific biomarker for crc clinical outcomes , so the prognosis of crc patients is poor .
recently , many lncrnas have been reported to play significant regulatory roles in human diseases .
cancer - specific lncrnas have been proven to contribute in tumor progression and serve as prognostic factors in many types of cancer .
wu et al . reported that lncrna uca1 could be a promising biomarker for early detection and prognosis in gastric cancer .
lncrna bancr was proved to regulate the growth and metastasis of the retinoblastoma cells and act as a prognostic target .
chen et al . demonstrated that lncrna hottip promoted pancreatic cancer cell proliferation , survival , and migration . as a result
, the association between crc and lncrnas may also provide significant information about the development of cancer and clinical outcomes .
lncrna spry4-it1 is a novel lncrna , which was first reported to be associated with molecular etiology in human melanoma .
it is a 687nt unspliced , polyadenylated transcript , localized at chromosome 5q31.3 . in this study
, we detected the relative expression levels of spry4-it1 in crc patients using qrt - pcr ( gapdh as normalized control ) , aiming to estimate the clinical significance of spry4-it1 in crc .
the results showed that the relative expression of spry4-it1 was much higher in diseased tissues than in the corresponding adjacent normal tissues and there were significant differences between them .
we also analyzed the relationship between the spry4-it1 expression and the clinical characteristics by chi - square method .
the results indicated that the relative expression levels of spry4-it1 were related to the tumor size , the depth of invasion , lymph node invasion , distant invasion , and tumor stage .
spry4-it1 expression was not relevant for sex , age , tumor location , histological differentiation , venous invasion , or nervous invasion .
these data suggest that spry4-it1 may play a role in the tumorigenesis and progression in crc .
the prognostic value of spry4-it1 in crc was also analyzed in this study . over - expression of spry4-it1
was correlated with low overall survival and the cox regression analysis showed that spry4-it1 could be an independent prognostic biomarker for crc .
similar results were also found in other types of cancer , and higher expression of spry4-it1 predicted poor prognosis in many cancers , such as gastric cancer , esophageal squamous cell carcinoma , clear cell renal cell carcinoma , and non - small cell lung cancer .
these studies indicated that spry4-it1 might be useful for providing insights into mechanisms of cancers development .
this study proves that spry4-it1 expresses aberrantly in diseased tissues of crc patients compared with the adjacent normal tissues .
moreover , the expression level is associated with tumor size , the depth of invasion , lymph node invasion , distant invasion , and tumor stage .
additional , spry4-it1 can act as an independent biomarker for crc prognosis and over - expression of spry4-it1 predicts poor prognosis in crc .
 backgroundlong non - coding rna spry4 intronic transcript 1 ( lncrna spry4-it1 ) has been reported to be associated with the progression of several cancers , but its expression level in colorectal cancer ( crc ) has rarely been reported . 
 the purpose of this study was to estimate the clinical significance of spry4-it1 in crc.material/methodsthe relative expression levels of spry4-it1 were detected by quantitative real - time polymerase chain reaction ( qrt - pcr ) in diseased tissues and the adjacent normal tissues of 106 crc patients . 
 chi - square method was used to evaluate the association between spry4-it1 expression and the clinical features . additionally , we assessed the overall survival at different expression levels of spry4-it1 using kaplan - meier method . 
 the prognostic significance of spry4-it1 was estimated by cox regression analysis.resultsup-regulated level of spry4-it1 was detected in pathologic tissues of crc patients compared with adjacent normal tissues ( p=0.000 ) . 
 the relative expression of spry4-it1 was associated with the tumor size , the depth of invasion , lymph node invasion , distant invasion , and tumor stage ( p<0.05 ) . 
 patients with high expression of spry4-it1 had poor overall survival compared with those with high level ( 39.3 vs. 49.3 months , log - rank test , p=0.016 ) . 
 cox regression analysis showed that spry4-it1 could act as an independent prognostic factor in crc ( hr=2.341 , 95% ci=1.1364.826 , p=0.021).conclusionsspry4-it1 might be associated with tumorigenesis and progression of crc , and it may be a promising biomarker for prognosis in patients with crc . 