in women , cervical cancer is the second most common malignant tumor worldwide and is one of the leading causes of cancer - related death in developing countries .
although the incidence of cervical cancer is generally decreasing , it is still a serious public health problem worldwide , especially in developing countries , and the average age of cervical cancer patients is decreasing .
human papillomavirus ( hpv ) is considered the major cause of cervical cancer , but viral infection alone is not sufficient for its development .
the pathogenesis of cervical cancer is still unclear and probably involves aberrant expression of numerous oncogenes and anti - oncogenes .
many distinct advances have been made in the prevention , surgical resection , radiotherapy , and chemotherapy of cervical cancer , but the prognosis of cervical cancer patients remains poor .
therefore , it is important to better understand molecular events in the invasion and metastasis of cervical cancer and to develop novel prognostic markers and therapeutic strategies .
stromal cell - derived factor-1 ( sdf-1 ) , which is a chemoattractant cytokine , is involved in a variety of physiological and pathological activities . with regard to cancer
, substantial evidence indicated that sdf-1 plays crucial roles in the cell growth , apoptosis , invasion , and metastasis of many kinds of cancers [ 79 ] .
it is well acknowledged that chronic inflammation is widely connected with the initiation and progression of cervical cancer .
inflammatory cytokines such as chemokines , inflammatory proteins , and adhesion molecules are known as the main causes of chronic inflammation .
numerous studies have revealed that nf-b , as a transcription factor , is cheifly responsible for the activity of these cytokines   and is also implicated in the development of a wide range of cancers .
however , to the best of our knowledge , the final role of sdf-1and nf-b in cervical cancer remains unclear . in the present study
, we used tissue microarray and the immunohistochemistry method to detect the expression of sdf-1and nf-b in 105 cases of human cervical cancer tissues and their paired adjacent tissues .
the purpose of this study was to investigate the association of sdf-1and nf-b expression with clinicopathological parameters of cervical cancer and to evaluate the prognostic value of sdf-1and nf-b expression in cervical cancer patients .
we analyzed a total of 105 formalin - fixed , paraffin - embedded cervical cancer tissues and the adjacent tissues at the time of operation from january 2002 to november 2013 at east hospital , tongji university .
all these cancer tissues were confirmed as cervical cancer by medical examination and hematoxylin and eosin staining after surgical resection .
none of the patients received adjuvant chemotherapy , radiation therapy , or other anti - tumor therapies .
important related clinicopathological parameters of the patients , such as age , tumor size , figo stage , lymphatic metastasis , stromal invasion , differentiation , and survival time , were obtained from each patient s medical records and are shown in tables 1 and 2 .
the survival time was calculated from the date of surgery to the date of death , or the last known follow - up .
all cervical cancer tissue samples included in this investigation were obtained with patients written informed consent .
a standard immunohistochemistry method was used to study sdf-1and nf-b expression in cervical cancer tissues and the adjacent tissues .
briefly , the tumor tissues and adjacent tissues were fixed in 10% formaldehyde and embedded in paraffin and then we cut the paraffin sections into 4-m sections .
all the 4-m tissue sections were dewaxed and rehydrated with xylene and graded alcohol , respectively . we washed the sections with buffer solution for 5 min and then added the primary antibody into them at 4c overnight .
after that , we washed the sections again and added the second antibody ( r&d systems inc . , minneapolis , mn ; dilution 1:50 ) into the sections .
afterwards , we washed the sections with phosphate - buffered saline ( pbs ) and developed them with 3 , 3-diaminobenzidine ( dab ) for 5 min and counterstained them with hematoxylin .
results are presented as the percentage of the staining cells ( 0 to 100% ) in tissues .
staining under 20% of the tissue cells or no staining was included in the negative group (  ) , while the others belonged to the positive group ( + ) .
all the sections were assessed under an optical microscope by 2 independent investigators , and any discrepancy in immunohistochemistry was resolved by consensus .
the expression of sdf-1 and nf-b in cervical cancer and adjacent cancer tissues was compared with the paired wilcoxon test .
chi - square test and fisher s exact test were used to assess the association between clinical characteristics of cervical cancer patients and sdf-1and nf-b expression .
the prognosis of cervical cancer and sdf-1and nf-b expression were determined using kaplan - meier survival analysis and log - rank test for univariate analysis .
all statistical analyses were performed using spss version 18.0 software ( spss inc . , chicago , il ) .
we analyzed a total of 105 formalin - fixed , paraffin - embedded cervical cancer tissues and the adjacent tissues at the time of operation from january 2002 to november 2013 at east hospital , tongji university .
all these cancer tissues were confirmed as cervical cancer by medical examination and hematoxylin and eosin staining after surgical resection .
none of the patients received adjuvant chemotherapy , radiation therapy , or other anti - tumor therapies .
important related clinicopathological parameters of the patients , such as age , tumor size , figo stage , lymphatic metastasis , stromal invasion , differentiation , and survival time , were obtained from each patient s medical records and are shown in tables 1 and 2 .
the survival time was calculated from the date of surgery to the date of death , or the last known follow - up .
all cervical cancer tissue samples included in this investigation were obtained with patients written informed consent .
a standard immunohistochemistry method was used to study sdf-1and nf-b expression in cervical cancer tissues and the adjacent tissues . briefly , the tumor tissues and adjacent tissues were fixed in 10% formaldehyde and embedded in paraffin and then we cut the paraffin sections into 4-m sections .
all the 4-m tissue sections were dewaxed and rehydrated with xylene and graded alcohol , respectively .
we washed the sections with buffer solution for 5 min and then added the primary antibody into them at 4c overnight .
after that , we washed the sections again and added the second antibody ( r&d systems inc . , minneapolis , mn ; dilution 1:50 ) into the sections .
afterwards , we washed the sections with phosphate - buffered saline ( pbs ) and developed them with 3 , 3-diaminobenzidine ( dab ) for 5 min and counterstained them with hematoxylin .
results are presented as the percentage of the staining cells ( 0 to 100% ) in tissues .
staining under 20% of the tissue cells or no staining was included in the negative group (  ) , while the others belonged to the positive group ( + ) .
all the sections were assessed under an optical microscope by 2 independent investigators , and any discrepancy in immunohistochemistry was resolved by consensus .
the expression of sdf-1 and nf-b in cervical cancer and adjacent cancer tissues was compared with the paired wilcoxon test . chi - square test and fisher s exact test were used to assess the association between clinical characteristics of cervical cancer patients and sdf-1and nf-b expression .
the prognosis of cervical cancer and sdf-1and nf-b expression were determined using kaplan - meier survival analysis and log - rank test for univariate analysis .
all statistical analyses were performed using spss version 18.0 software ( spss inc . , chicago , il ) .
typical immunohistochemistry images of sdf-1 and nf-b in cervical cancer tissues and paired adjacent non - tumor tissues are shown in figures 1 and 2 .
the positive percentage of sdf-1 expression in cervical cancer and adjacent non - tumor tissues were 68.6% ( 72/105 ) and 8.6% ( 9/105 ) , respectively . the positive percentage of nf-b expression in cervical cancer and adjacent non - tumor tissues were 60.0% ( 63/105 ) and 5.7% ( 6/105 ) , respectively .
the chi - square test was used to confirmed that the difference in the expression level of sdf-1and nf-b between cervical cancer tissues and paired adjacent non - tumor tissues was statistically significant ( p<0.05 ) .
the relationship between patients clinical parameters and the expression of sdf-1and nf-b is shown in tables 1 and 2 , respectively , showing that the expression of sdf-1 in the cervical cancer tissues is significantly correlated with tumor size ( =10.794 , p=0.001 ) and figo histology grade ( =7.000 , p=0.008 ) . however , there was no statistical correlation between sdf-1 expression and patient age , lymph node metastasis ( lnm ) status , stromal invasion , or tumor differentiation ( p>0.05 ) .
similarly , the expression of nf-b in the cervical cancer tissues was significantly correlated with tumor size ( =7.421 , p=0.006 ) , figo histology grade ( =10.182 , p=0.001 ) , and lymph node metastasis ( lnm ) status ( =4.762 , p=0.029 ) .
however , there was no statistical correlation was found between nf-b expression with patient age and stromal invasion and tumor differentiation ( p>0.05 ) .
therefore , the results demonstrate that higher sdf-1 and nf-b expression in cervical cancer tissues is positively correlated with tumor metastasis and cancer progression , suggesting that sdf-1and nf-b play important roles in the progression . to further evaluate the relationship between sdf-1and nf-b expression and prognosis of cervical cancer , we performed log - rank survival analysis according to the sdf-1 and nf-b expression level and patient survival data .
the survival analysis demonstrates that the cervical survival rate of the patients with negative sdf-1 and nf-b expression is significantly better than that of the patients with positive ones ( p<0.05 , figures 3 , 4 ) .
furthermore , a multivariate cox regression analysis demonstrated that sdf-1 expression and lymph node metastasis are independent predictors of the os in cervical cancer patients .
the expression of sdf-1 was positively correlated with the expression of nf-b ( r=0.201 , p=0.040 ; table 3 ) .
typical immunohistochemistry images of sdf-1 and nf-b in cervical cancer tissues and paired adjacent non - tumor tissues are shown in figures 1 and 2 .
the positive percentage of sdf-1 expression in cervical cancer and adjacent non - tumor tissues were 68.6% ( 72/105 ) and 8.6% ( 9/105 ) , respectively . the positive percentage of nf-b expression in cervical cancer and adjacent non - tumor tissues were 60.0% ( 63/105 ) and 5.7% ( 6/105 ) , respectively .
the chi - square test was used to confirmed that the difference in the expression level of sdf-1and nf-b between cervical cancer tissues and paired adjacent non - tumor tissues was statistically significant ( p<0.05 ) .
the relationship between patients clinical parameters and the expression of sdf-1and nf-b is shown in tables 1 and 2 , respectively , showing that the expression of sdf-1 in the cervical cancer tissues is significantly correlated with tumor size ( =10.794 , p=0.001 ) and figo histology grade ( =7.000 , p=0.008 ) .
however , there was no statistical correlation between sdf-1 expression and patient age , lymph node metastasis ( lnm ) status , stromal invasion , or tumor differentiation ( p>0.05 ) .
similarly , the expression of nf-b in the cervical cancer tissues was significantly correlated with tumor size ( =7.421 , p=0.006 ) , figo histology grade ( =10.182 , p=0.001 ) , and lymph node metastasis ( lnm ) status ( =4.762 , p=0.029 ) .
however , there was no statistical correlation was found between nf-b expression with patient age and stromal invasion and tumor differentiation ( p>0.05 ) .
therefore , the results demonstrate that higher sdf-1 and nf-b expression in cervical cancer tissues is positively correlated with tumor metastasis and cancer progression , suggesting that sdf-1and nf-b play important roles in the progression .
to further evaluate the relationship between sdf-1and nf-b expression and prognosis of cervical cancer , we performed log - rank survival analysis according to the sdf-1 and nf-b expression level and patient survival data .
the survival analysis demonstrates that the cervical survival rate of the patients with negative sdf-1 and nf-b expression is significantly better than that of the patients with positive ones ( p<0.05 , figures 3 , 4 ) .
furthermore , a multivariate cox regression analysis demonstrated that sdf-1 expression and lymph node metastasis are independent predictors of the os in cervical cancer patients .
the expression of sdf-1 was positively correlated with the expression of nf-b ( r=0.201 , p=0.040 ; table 3 ) .
it has 2 major isoforms :  and . both are derived from a single gene due to alternative splicing .
it is well acknowledged that sdf-1 mediates a large number of crucial biological processes such as neuronal and cardiac development , angiogenesis , apoptosis , and stem cell motility .
substantial evidence indicates that sdf-1 can mediate the activation of sdf-1/crcr4-pi3-mark - nf-b pathway , pi3k / akt , wnt , and erk pathways , and further promotes the invasion and progression of cancers [ 1719 ] .
sdf-1 can also improve the expression of mmps and vegf , which are crucial for the aggressive behavior of cancers .
many studies have revealed that the over - expression of sdf-1 is found in various malignancies , including lung cancer , prostate cancer , breast cancer , and pancreatic cancer .
the nf - kb transcription factor family includes 5 genes : nf-b1 ( p50/p105 ) , nf-b2 ( p52/p100 ) , rela ( p65 ) , c - rel , and relb
. normally , nf - kb dimmers are transcriptionally inactive due to their interaction with nf - kb inhibitors ( i kbs ) .
activation of nf-b may result from the enhanced expression of epidermal growth factor receptor , insulin growth factor receptor , and tumor necrosis factor receptor families .
activation of some other pathways , like pi3k / akt and ras / mapk , also participate in the activation of nf-b .
some different kinds of molecular alterations in cancer cells may lead to impaired regulation of nf-b activation .
in this situation , nf - kb becomes constantly activated , which leads to aberrant expression of downstream genes of nf-b , including those involved in regulation of cell cycle , proliferation , adhesion , and apoptosis .
these pathophysiological changes may finally lead to the initiation , development , and metastasis of cancer .
the results of this study indicate that the expression of sdf-1 is increased in cervical cancer tissues and is correrated with tumor size and figo histology grade .
we found that the expression of nf-b is increased in cervical cancer tissues and is correrated with tumor size , figo histology grade , and lymph node metastasis .
the potential mechanism may be that sdf-1 activates the nf-b pathway by the interaction with cxcr4 .
the sdf-1/crcr4-nf-b pathway participates in the regulation of cell prliferation , apoptosis , and angiogenesis in cervical cancer .
the increased expression of vegf and mmps caused by sdf-1-cxcr4 interaction and many nf-b - related biological macular - involved cell cycle , apoptosis , and chronic inflammation responses may mediate the initiation and progression of cervical cancer [ 3032 ] .
it is well known that cancer pathogenesis is a multi - factor , multi - step , complicated process involved in gene - gene and gene - environment interactions .
large and well - designed studies are still needed to elucidate the pathogenesis of cervical cancer .
results of our study indicate that the expression of sdf-1 is significantly associated with tumor size and figo histology grade .
the expression of nf-b is significantly associated with tumor size , figo histology grade , and lymph node metastasis .
we also found that positive sdf-1 or nf-b expression is significantly correlated with poor prognosis .
 backgroundsdf-1 and nf-b are associated with the prognosis of a wide range of cancers , but their value in cervical cancer remains controversial . 
 the aim of this study was to investigate the expression of sdf-1and nf-b in cervical cancer and their significance in clinical prognosis.material/methodsthe expression of sdf-1and nf-b in 105 formalin - fixed , paraffin - embedded cervical cancer tissues and the adjacent tissues was examined by immunohistochemistry ( ihc ) . 
 the results were semi - quantitatively scored and analyzed by chi - square test . the overall survival times ( os ) 
 were collected by follow - up and analyzed by kaplan - meier analysis.resultsthe expression level of both sdf-1and nf-b in cervical cancer are higher than that in the adjacent tissues ( p<0.05 ) . 
 sdf-1 expression are correlated with tumor size and figo histology grade ( p<0.05 ) . 
 nf-b expression are correlated with tumor size and figo histology grade , and lymph node metastasis ( lnm ) status ( p<0.05 ) . 
 the patients with a positive expression of sdf-1or nf-b tended to have much shorter survival time than patients with negative expression . 
 in addition , multivariate cox regression analysis demonstrated that sdf-1 expression and lymph node metastasis are independent predictors of the os in cervical cancer patients.conclusionsthe expression of sdf-1 is significantly associated with tumor size and figo histology grade . 
 the expression of nf-b is significantly associated with tumor size , figo histology grade , and lymph node metastasis . 
 the positive sdf-1or nf-b expression is significantly correlated with poor prognosis . 
 these may be valuable biomarkers for the prognosis and the potential therapeutic targets of cervical cancer . 
Background
Material and Methods
Patients and tissues specimens
Immunohistochemical staining
Statistical analysis
Results
Expression of SDF-1and NF-B significantly increased in cervical cancer tissues
Increased expression of SDF-1and NF-B correlates with clinicopathological parameters of patients with cervical cancer
Correlation between SDF-1and NF-B and prognosis of cervical cancer patients
Correlation between the expression of SDF-1and NF-B in cervical cancer
Discussion
Conclusions