Correlation Of Transcription Factor FOXC1 With Clinicopathologic Features In Gynecological Tumors

Objective Transcription factors are a group of modular proteins which are involved in a wide variety of biological processes of development, differentiation and metabolism through regulating their target genes. The conserved members of forkhead box(FOX)/winged-helix transcription factor family, whose nomenclature were revised in 2000, have the same basic design in their interaction with DNA through specific DNA-binding forkhead domain. In recent years the function of FOX genes has become better understood in controlling processes, including regulation of maintenance of differentiated cell states, embryogenesis, cell cycle, glycometabolism and cell apoptosis. In addition to their vital roles in normal development processes, a number of mutant FOX genes also participate in development malformation and tumorigenesis.Transcription factor FOXC1 is a member of FOX family. Studies on animal models have demonstrated the importance of FOXC1 as a developmentally key transcription factor. Mutations of FOXC1 gene in human result in various glaucoma-related phenotypes, e.g. Axenfeld-Rieger syndrome (ARS) is an autosomal dominantly inherited developmental disorder in which patients present with ocular and non-ocular clinical findings. Ocular characteristics include hypoplasia of the anterior iris stroma, microcornea, anterior chamber synechiae, corneal opacity, and juvenile onset glaucoma. Nonocular features typically include maxillary hypoplasia, hypodontia, and failure of involution of the periumbilical skin. Previous study also revealed FOXC1 might be involved in several types of genital tumorigenesis, such as human prostate, endometrial and ovarian cancers.However, it was unclear whether FOXC1 protein exists in gynecological tumor tissues. In addition, its clinical significance of FOXC1 protein in gynecological tumor remains poorly understood. This study was designed to clarify the problem and explore the association of FOXC1 protein expression with clinicopathologic factors and outcome of the diseases.Methods Two human serous ovarian cystadenocarcinoma cell lines, SKOV-3 and HO-8910 cells were cultured in vitro. Eighty cases of serous ovarian tumor (including 25 ovarian cystoadenoma, 15 ovarian borderline serous cystoadenoma and 40 serous ovarian cystadenocarcinoma), 54 cervical cancer and 23 endometrial cancer, all paraffin embeded, were retrieved from case files in Department of Pathology of 2nd Affiliated Hospital of Chongqing Medical University between February, 2004 and February, 2009. Seven cases of serous ovarian tumor(including 2 ovarian cystoadenoma, 2 borderline ovarian cystoadenoma, and 3 serous ovarian cystadenocarcinoma), normal ovarian tissues and normal endometrial tissue as positive control, were recruited from gynecological operations of 2nd Affiliated Hospital of Chongqing Medical University between December, 2008 and February, 2009. Western-blot and immunohistochemistry were employed to dectect FOXC1 protein level in 2 ovarian cancer cell lines. In situ hybridization and RT-PCR were used to measure FOXC1 mRNA level in normal endometrium,normal ovarian tissue and ovarian tumors. Immunohistochemistry were employed to determine FOXC1 protein level in paraffin-bedded tumor tissues, including ovarian tumor, cervical cancer and endometrial cancer tissues. The relationships between FOXC1 protein expression of paraffin-bedded tumor tissues and clinicopathologic parameters were examined by Chi-square test or Fisher's Exact Test and correlation test.Results⑴FOXC1 mRNA expression was confirmed in normal endometrium and ovarian tumor tissues. FOXC1 protein was revealed in 2 ovarian cancer cell lines, 46(57.5%)cases of ovarian tumor, 29(53.7 %)cervical cancer and 20(87.0 %)endometrial cancer.⑵Positive reactivity was found in 21 (84%) cases of serous ovarian cystoadenoma, in 10 (66.7%) serous ovarian borderline cystoadenoma, and in 15 (37.5%) serous ovarian cystadenocarcinoma. Chi-square test showed a significant correlation between positive FOXC1 immunoreactivity and pathological subtypes of serous ovarian tumor (P<0.01) and FOXC1 protein levels significantly decreased with advancing FIGO stages (Ⅰ~ⅡvsⅢ~Ⅳ) and serum CA125 levels(P<0.05). No significant association was shown between FOXC1 protein expression and clinicopathological factors including age, histological grade and volumes of ascites (P>0.05).⑶Significant correlation in retrospective study was observed between FOXC1 protein expression and histological grades (P<0.05) in cervical cancer. No significant association was shown between FOXC1 protein expression in cervical cancer and clinicopathological factors including pathological types, FIGO stages, lymph node metastasis and etc.⑷No significant association was shown between FOXC1 protein expression in endometrial cancer and clinicopathological factors including pathological types, histological grades, FIGO stages, myometrial invasion and involvement of cervix and adnexa, and lymph node metastasis (P>0.05).Conclusion⑴Expression levels of FOXC1 protein in paraffin-bedded tissues of serous ovarian cystoadenoma and serous ovarian borderline cystoadenoma were revealed to be significantly higher than in serous ovarian cystadenocarcinoma. There was also a decreasing trend of FOXC1 protein expression with increased histological grades. Positive FOXC1 expression in serous ovarian cystadenocarcinoma was found correlated with FIGO stages, while there was a significantly correlation between FOXC1 expression and serum CA125 levels. Loss of FOXC1 expression may be an early event in serous ovarian tumorigenesis.⑵FOXC1 expression in cervical cancer was revealed correlated with histological grades. Loss of FOXC1 expression may play an important role in genesis and development of cervical cancer.⑶FOXC1 expression may not play a role in genesis and development of endometrial cancer.