Tissue factor pathway inhibitor 2 as a serum biomarker for endometrial cancer: a single-center retrospective study.

BACKGROUND: Endometrial cancer is the most common gynecological malignancy; however, there is no useful blood diagnostic biomarker. This study aimed to determine the utility of tissue factor pathway inhibitor 2 (TFPI2), a biomarker of ovarian cancer, as a diagnostic marker for endometrial cancer. METHODS: We examined serum TFPI2 levels in patients with endometrial cancer (n = 328) compared to those in healthy controls (n = 65) and evaluated the performance of serum TFPI2 levels as a diagnostic marker. We investigated the clinicopathological characteristics of patients with TFPI2-negative and TFPI2-positive endometrial cancer. Using immunohistochemistry (IHC), we examined TFPI2 expression in tumor tissues of 105 patients with type II endometrial carcinoma and evaluated the correlation between serum and tissue TFPI2 positivity. RESULTS: Patients with endometrial cancer had significantly higher serum TFPI2 levels than controls (196.7 pg/mL vs. 83.3 pg/mL; p < 0.001). The sensitivity and specificity were 54.3% and 95.4%, respectively (cutoff value, 191 pg/mL). Serum TFPI2 levels were significantly elevated along with the stage progression (stage I, 189.6 pg/mL; stage III, 230.9 pg/mL; stage IV, 312.5 pg/mL; p < 0.001). Patients with high-risk histology showed significantly elevated serum TFPI2 levels than those with low-risk histology (220.8 pg/mL vs. 187.7 pg/mL; p < 0.001). The positivity rate for TFPI2 was the highest among tumor markers, including CA125, CA19-9, and CEA. Serum TFPI2 and CA125 levels were almost independent (r = 0.203, p < 0.001), and the combined sensitivity increased to 58.8%. The 5-year survival rate was significantly worse in TFPI2-positive patients (≥ 191 pg/mL, n = 178) than in TFPI2-negative patients (< 191 pg/mL, n = 150) (hazard ratio, 8.22; 95% confidence interval, 2.49-27.1; p < 0.001). TFPI2 immunostaining revealed that 37.1% (39/105) of the samples were positive for TFPI2, with an IHC score of > 0. There was no significant difference in the immunostaining score according to histological type. Serum TFPI2 levels and immunostaining score showed poor agreement (kappa coefficient, -0.039). CONCLUSIONS: The serum TFPI2 level is a promising marker for diagnosing and predicting the prognosis of endometrial cancer. No correlation exists between serum and tissue TFPI2 levels. Further multicenter clinical trials are needed to test the utility of TFPI2 as a diagnostic marker.

Tissue Factor Pathway Inhibitor 2: A Novel Biomarker for Predicting Asymptomatic Venous Thromboembolism in Patients with Epithelial Ovarian Cancer.

OBJECTIVES: Patients with asymptomatic venous thromboembolism (VTE) are associated with an increased risk of pulmonary thromboembolism events. However, due to low specificity and high false-positive rates, D-dimer testing cannot be used alone to diagnose VTE. Tissue factor pathway inhibitor 2 (TFPI2), a new serodiagnostic marker for ovarian cancer, plays a role in blood coagulation system regulation. We hypothesized that combining D-dimer and TFPI2 would improve its utility in diagnosing VTE. This study aimed to look into the clinical utility of serum D-dimer and TFPI2 levels in detecting asymptomatic VTE in patients with epithelial ovarian cancer (EOC). DESIGN: From January 2008 to December 2015, researchers at Nara Medical University Hospital's Department of Gynecology conducted a single-center retrospective study. The receiver operating characteristic (ROC) curve analysis was used to determine the diagnostic value of preoperative D-dimer, TFPI2, and D-dimer combined with TFPI2 in distinguishing VTE patients from those who did not have VTE. PARTICIPANTS: This study included 122 patients with EOC who met the inclusion and exclusion criteria out of 223 admitted to the hospital with EOC. The patients were divided into two groups: VTE (n = 25) and non-VTE (n = 97). RESULTS: There were significant differences in D-dimer, TFPI2, and CA125 levels and residual tumor between the VTE and non-VTE groups. The D-dimer level was found to be significantly related to age, body mass index, VTE, massive ascites, residual tumor, histology, and Federation of Gynecology and Obstetrics stage, whereas the TFPI2 level was only related to VTE. Multivariate analysis revealed that D-dimer (the optimal cutoff value, 3.5 µg/mL) and TFPI2 (the optimal cutoff value, 400 pg/mL) are independent risk factors for preoperative VTE. ROC analysis revealed that the area under the curve was 0.8266 for D-dimer, 0.7963 for TFPI2, and 0.8495 for the combination of D-dimer and TFPI2. When compared to the D-dimer test alone, the combination of D-dimer and TFPI2 had higher specificity (77.3-96.9%) and positive predictive value (48.8-81.2%) for the diagnosis of VTE. LIMITATIONS: This is a single-center retrospective study. CONCLUSION: The combination of D-dimer and TFPI2 may be useful to safely exclude VTE and select patients at high risk of VTE.

Tissue factor pathway inhibitor 2: A potential diagnostic marker for discriminating benign from malignant ovarian tumors.

OBJECTIVES: Carbohydrate antigen 125 (CA125), CA19-9, carcinoembryonic antigen (CEA), human epididymis protein 4 (HE4), and the Risk of Ovarian Malignancy Algorithm (ROMA) are widely used as tumor markers and algorithms for the diagnosis of ovarian cancer (OC). Tissue factor pathway inhibitor 2 (TFPI2) has been developed as a potential serodiagnostic marker for OC in Japan. The aim of this study is to evaluate the diagnostic accuracy of the six markers alone and in combination to find the best marker for discriminating between benign and malignant ovarian tumors. METHODS: Frozen serum samples collected from 484 patients were divided into three groups based on histopathological results: OC (n = 119), borderline ovarian tumors (BR) (n = 48), and benign ovarian tumors (BN) (n = 317). Diagnostic accuracy was calculated with an area under a receiver operating characteristic (AUC) curve. RESULTS: TFPI2 achieved the highest discrimination between the OC + BR group versus the BN group (AUC 0.8076). ROMA values best discriminated patients with OC from those with BN (AUC, 0.8966), which was equivalent to TFPI2 (AUC, 0.8937). For discriminating the OC group from the BR + BN group, the highest AUC value was achieved by ROMA values (AUC, 0.8884), and TFPI2 also showed comparable diagnostic accuracy (AUC, 0.8845). Combining TFPI2 with ROMA had the highest AUC (0.8420-0.9357). CONCLUSION: TFPI2 may be a clinically useful single marker comparable to conventional ROMA values for discriminating between benign and malignant ovarian tumors.

Tissue factor pathway inhibitor 2 as a serum marker for diagnosing asymptomatic venous thromboembolism in patients with epithelial ovarian cancer and positive D-dimer results.

Tissue factor pathway inhibitor 2 (TFPI2) is a serodiagnostic marker for epithelial ovarian cancer (EOC) and is the primary inhibitor of the extrinsic coagulation pathway. The present study assessed the diagnostic performance of TFPI2 for detecting venous thromboembolism (VTE) in patients with EOC and positive D-dimer results (>1.0 µg/ml). First, the clinical data of 81 patients with EOC admitted to Nara Medical University Hospital between January 2008 and December 2015 were collected. Also, 25 patients with VTE and 56 patients without VTE were included. Receiver-operating characteristic (ROC) curve analyses were performed to determine the diagnostic efficacy of TFPI2 in discriminating patients with VTE from those without VTE. Serum TFPI2 levels in patients with VTE were significantly higher than in non-VTE patients (median, 472.2 vs. 279.1 pg/ml, P<0.001). Using the Youden index, the optimal cutoff value for the TFPI2 level was set at 398.9 pg/ml. Furthermore, the sensitivity, specificity, positive predictive value and negative predictive value of TFPI2 for diagnosing VTE were 64.0, 80.4, 59.3 and 83.3%, respectively. Additionally, 80.4% of patients with TFPI2 levels <398.9 pg/ml were VTE-negative. ROC analysis demonstrated that the area under the curve for TFPI2 was 0.729 (95% confidence interval, 0.614-0.844). Conclusively, TFPI2 may distinguish patients with VTE from those without VTE among patients with EOC and positive D-dimer results.

Tissue factor pathway inhibitor­2 is specifically expressed in ovarian clear cell carcinoma tissues in the nucleus, cytoplasm and extracellular matrix.

Tissue factor pathway inhibitor­2 (TFPI­2) is a promising candidate as a serum biomarker of ovarian clear cell carcinoma (OCCC), a lethal histological subtype of epithelial ovarian cancer (EOC). TFPI­2 is a secreted serine protease inhibitor that suppresses cancer progression through the inhibition of matrix protease activities. Previous studies have also identified TFPI­2 in the nucleus, and a possible function of nuclear TFPI­2 as a transcriptional repressor of matrix metalloproteinase­2 (MMP­2) was recently demonstrated. We are currently establishing TFPI­2 as a serum biomarker for OCCC patients; however, TFPI­2 expression in OCCC tissues has not been previously investigated. In the present study, we examined TFPI­2 expression and its localization in 11 OCCC cell lines by western blotting and enzyme­linked immune assay. Four cell lines expressed TFPI­2 in the nucleus, cytoplasm and culture plate-attached extracellular fraction, while four other cell lines expressed TFPI­2 only in the extracellular fraction. In the remaining three cell lines, TFPI­2 was not identified in any fraction. The amount of secreted soluble TFPI­2 showed similar trends to that of the plate­attached fraction. We next investigated the expression levels and distribution of TFPI­2 in surgically resected EOC tissues by immunohistochemistry. In 52 of the 77 (67.5%) OCCC tumors, TFPI­2 expression was detected in at least one of the nuclear, cytoplasmic and extracellular matrix fractions. In contrast, we did not identify TFPI­2 in the other EOC subtypes (n=65). TFPI­2­positive expression distinguished CCC from the other EOC tissues with a sensitivity of 67.5% and specificity of 100%. Although the inherent tumor suppressor function, statistical analyses failed to demonstrate correlations between TFPI­2 expression and clinical parameters, including 5­year overall survival, except for the patient age. In conclusion, we identified TFPI­2 expression in the nucleus, cytoplasm and extracellular matrix in OCCC tissues. The high specificity of TFPI­2 may support its use for diagnosis of OCCC in combination with existing markers.

STPR, a 23-amino acid tandem repeat domain, found in the human function-unknown protein ZNF821.

The STPR motif is composed of 23-amino acid repeats aligned contiguously. STPR was originally reported as the DNA-binding domain of the silkworm protein FMBP-1. ZNF821, the human protein that contains the STPR domain, is a zinc finger protein of unknown function. In this study, we prepared peptides of silkworm FMBP-1 STPR (sSTPR) and human ZNF821 STPR (hSTPR) and compared their DNA binding behaviors. This revealed that hSTPR, like sSTPR, is a double-stranded DNA-binding domain. Sequence-independent DNA binding affinities and α-helix-rich DNA-bound structures were comparable between the two STPRs, although the specific DNA sequence of hSTPR is still unclear. In addition, a subcellular expression experiment showed that the hSTPR domain is responsible for the nuclear localization of ZNF821. ZNF821 showed a much slower diffusion rate in the nucleus, suggesting the possibility of interaction with chromosomal DNA. STPR sequences are found in many proteins from vertebrates, insects, and nematodes. Some of the consensus amino acid residues would be responsible for DNA binding and concomitant increases in α-helix structure content.

In vivo fluorescence correlation spectroscopy analyses of FMBP-1, a silkworm transcription factor.

Fibroin modulator-binding protein 1 (FMBP-1) is a silkworm transcription factor that has a unique DNA-binding domain called the one score and three amino acid peptide repeat (STPR). Here we used fluorescence correlation spectroscopy (FCS) to analyze the diffusion properties of an enhanced green fluorescent protein-tagged FMBP-1 protein (EGFP-FMBP-1) expressed in posterior silk gland (PSG) cells of Bombyx mori at the same developmental stage as natural FMBP-1 expression. EGFP-FMBP-1 clearly localized to cell nuclei. From the FCS analyses, we identified an immobile DNA-bound component and three discernible diffusion components. We also used FCS to observe the movements of wild-type and mutant EGFP-FMBP-1 proteins in HeLa cells, a simpler experimental system. Based on previous in vitro observation, we also introduced a single amino acid substitution in order to suppress stable FMBP-1-DNA binding; specifically, we replaced the ninth Arg in the third repeat within the STPR domain with Ala. This mutation completely disrupted the slowest diffusion component as well as the immobile component. The diffusion properties of other FMBP-1 mutants (e.g. mutants with N-terminal or C-terminal truncations) were also analyzed. Based on our observations, we suggest that the four identifiable movements might correspond to four distinct FMBP-1 states: (a) diffusion of free protein, (b) and