Expression of the chromatin remodeling factor Rsf-1 is upregulated in ovarian carcinoma effusions and predicts poor survival

Rsf‑1 regulates malignant melanoma cell viability and chemoresistance via NF‑κB/Bcl‑2 signaling

Remodeling and spacing factor 1 (Rsf-1) has been reported as overexpressed in numerous cancers; however, its expression, biological functions and mechanisms in malignant melanoma remain unknown. In the present study, the expression of Rsf-1 was investigated in 50 cases of malignant melanoma samples using immunohistochemistry. The results revealed that Rsf-1 expression was elevated in 38% of specimens. MTT, colony formation, Transwell and flow cytometry assays were performed to investigate the functions of Rsf-1. Knockdown of Rsf-1 in the MV3 and A375 melanoma cell lines decreased the viability, invasion and cell cycle transition of cells. Conversely, overexpression of Rsf-1 in M14 cells with low endogenous Rsf-1 expression induced opposing effects. Further analysis revealed that Rsf-1 knockdown decreased matrix metalloproteinase-2, cyclin E and phosphorylated-IκB expression. Additionally, Rsf-1 depletion reduced cisplatin resistance and significantly increased the cisplatin-associated apoptotic rate, whereas Rsf-1 overexpression exhibited opposing effects. Rsf-1 also maintained the mitochondrial membrane potential following cisplatin treatment. Analysis of apoptosis-associated proteins revealed that Rsf-1 positively regulated B-cell lymphoma 2 (Bcl-2), cellular inhibitor of apoptosis 1 (cIAP1) and cIAP2, and downregulated Bcl-2-associated X protein expression. Nuclear factor κ-light-chain-enhancer of activated B-cells (NF-κB) inhibition reversed the effects of Rsf-1 on Bcl-2. In conclusion, Rsf-1 was overexpressed in malignant melanoma and may contribute to the malignant behaviors of melanoma cells, possibly via the regulation of NF-κB signaling. Therefore, Rsf-1 may be a potential therapeutic target in the treatment of malignant melanoma.

RSF-1 overexpression determines cancer progression and drug resistance in cervical cancer

BACKGROUND

Remodeling spacing factor 1 (RSF-1/HBXAP) has been linked to a variety of cancer types, however, its roles and the therapeutic potential are not clear in cervical cancer.

METHODS

RSF-1 expression in cancer tissues was analyzed by immunohistochemical staining followed by statistical analysis with SPSS. Anti-RSF-1 studies were performed by treating cells with specific siRNA or a dominant mutant form (RSF-D4).

RESULTS

RSF-1 expression correlates with cancer progression that strongly-positive staining can be found in 67.7% carcinomas and 66.7% CIN lesions, but none in normal tissues. Such overexpression also associated with increased tumor size, poor differentiation, higher nodal metastasis and advanced clinical stages. Kaplan- Meier analysis confirmed that cancer patients with high RSF-1 levels exhibited a significantly shorter survival time than those with low RSF-1 levels. Downregulation of RSF-1 by siRNA silencing or RSF-D4 reduced cell growth and increased drug sensitivity toward paclitaxel treatment in HeLa cells.

CONCLUSIONS

RSF-1 participates in the tumor progression of cervical cancer and could be considered as an early prognostic marker for cancer development and clinical outcome. Therapies based on anti-RSF-1 activity may be beneficial for patients with RSF-1 overexpression in their tumors.

Remodeling and spacing factor 1 overexpression is associated with poor prognosis in renal cell carcinoma

The present study aimed to assess the expression and prognostic significance of remodeling and spacing factor 1 (RSF1; HBXAP) in renal cell carcinoma (RCC). RSF1 expression was analyzed using immunohistochemistry on tissue samples from a consecutive series of 137 patients with RCC who underwent tumor resection between November 2000 and March 2004. The associations between RSF1 expression, clinicopathological factors and patient survival were investigated. Immunohistochemistry revealed that RSF1 was highly expressed in 43.1% (59/137) of the RCC samples. RSF1 expression levels were associated with the T stage of the Tumor-Node-Metastasis grading system. Kaplan-Meier survival analysis indicated that high RSF1 expression in RCC was significantly associated with a poor prognosis. Multivariate analysis revealed that RSF1 expression is an independent prognostic parameter for the duration of overall survival of patients with RCC. The results demonstrated that a high expression level of RSF1 in RCC is associated with advanced tumor stages and a poor prognosis. To the best of our knowledge, the present study provides novel evidence of the biological significance of RSF1 expression in RCC.

Overexpression of Rsf-1 correlates with poor survival and promotes invasion in non-small cell lung cancer

Rsf-1 (HBXAP) was recently reported to play roles in tumorigenesis and tumor progression. There have been many reports referred to Rsf-1 overexpression in various cancers and associated with the malignant behavior of cancer cells. However, the molecular mechanism of Rsf-1 in non-small cell lung cancer aggressiveness remains ambiguous. In the present study, we found that there was a significant association between Rsf-1 overexpression and poor overall survival (p = 0.028) in lung cancer. Furthermore, knockdown of Rsf-1 expression in H1299 and H460 cells with high endogenous Rsf-1 expression inhibited cell migration and invasion and downregulated MMP2 expression and nuclear levels of NF-κB. NF-κB inhibitor could also block the effect of Rsf-1 in regulation of MMP2 expression. Further experiments demonstrated that Rsf-1 depletion restrained NF-κB reporter luciferase activity and downregulated bcl-2 and p-IκB protein level. In conclusion, we demonstrated that Rsf-1 was overexpressed in lung cancer and associated with poor survival. Rsf-1 regulated cell invasion through MMP2 and NF-κB pathway.

Rsf-1 overexpression serves as a prognostic marker in human hepatocellular carcinoma

Rsf-1 (HBXAP) was recently reported to be overexpressed in various cancers and associated with the malignant behavior of cancer cells. However, the expression of Rsf-1 and its clinical significance in human hepatocellular carcinoma (HCC) have not been reported. In the present study, we analyzed the expression pattern of Rsf-1 in human HCC tissues and found that Rsf-1 was overexpressed in 41.1 % of HCC specimens. There was a significant association between Rsf-1 overexpression and tumor stage (p = 0.0322), AFP (p = 0.0184), and tumor relapse (p = 0.0112). Furthermore, Rsf-1 overexpression correlated with poor overall survival in HCC patients (p < 0.001). Rsf-1 overexpression could serve as an independent predictor for poor recurrence-free survival (p = 0.0079). Small interfering RNA (siRNA) knockdown in SK-Hep-1 cells with high endogenous Rsf-1 expression inhibited cell proliferation and colony formation, with downregulation of cyclin E protein. In conclusion, Rsf-1 is overexpressed in HCCs and serves as a novel tumor marker. Rsf-1 contributes to hepatocellular carcinoma cell growth through regulation of cell cycle proteins.

Rsf-1 overexpression in human prostate cancer, implication as a prognostic marker

Rsf-1 (HBXAP) was recently reported to be overexpressed in various cancers and associated with the malignant behavior of cancer cells. However, the expression of Rsf-1 and its clinical significance in human prostate cancer have not been reported. In the present study, we analyzed the expression pattern of Rsf-1 in human prostate cancer tissues and found that Rsf-1 was overexpressed in 45 % of prostate cancer specimens. There was a significant association between Rsf-1 overexpression and tumor stage (p=0.0039) and preoperative PSA level (p=0.015). Furthermore, Rsf-1 overexpression correlated with poor biomedical recurrence-free survival in prostate cancer patients (p<0.001). Rsf-1 overexpression could serve as an independent predictor for poor recurrence-free survival (p=0.012). In addition, small interfering RNA (siRNA) knockdown in DU145 cells with high endogenous Rsf-1 expression decrease cell proliferation, colony formation, and invasion. In conclusion, Rsf-1 is overexpressed in human prostate cancers and serves as a novel prognostic marker. Rsf-1 contributes to prostate cancer cell growth and invasion, which makes it a candidate therapeutic target.

RSF1 is a positive regulator of NF-κB-induced gene expression required for ovarian cancer chemoresistance

Overexpression or amplification of the RSF1 gene has been associated with poor prognosis in various human cancers, including ovarian cancer. In previous work, RSF1 was identified as an amplified gene that facilitated the development of paclitaxel-resistant ovarian cancer. In the present study, we further demonstrated that RSF1 expression inversely correlated with paclitaxel response in patients with ovarian cancer and the mouse xenograft model. In addition, RSF1-overexpressing paclitaxel-resistant ovarian cancer cell lines were found to express elevated levels of genes regulated by NF-κB, including some involved with the evasion of apoptosis (CFLAR, XIAP, BCL2, and BCL2L1) and inflammation (PTGS2). In addition, ectopic expression of RSF1 using Tet-off inducible SKOV3 cells significantly enhanced NF-κB-dependent gene expression and transcriptional activation of NF-κB. An RSF1 knockdown using short hairpin RNAs suppressed these same pathways. Moreover, pretreatment with NF-κB inhibitors or downregulation of NF-κB-regulated gene expression considerably enhanced paclitaxel sensitivity in RSF1-overexpressing OVCAR3 and/or RSF1-induced SKOV3 cells. A coimmunoprecipitation assay revealed that RSF1 interacts with NF-κB and CREB-binding protein, a ubiquitous coactivator for NF-κB. Recruitment of RSF1 to the NF-κB binding element in the PTGS2 and XIAP promoters was demonstrated by the chromatin immunoprecipitation assay. Furthermore, hSNF2H, a well-known binding partner of RSF1, was partially involved in the interaction between RSF1 and NF-κB. Taken together, these data suggest that RSF1 may function as a coactivator for NF-κB, consequently augmenting expression of genes necessary for the development of chemoresistance in ovarian cancer cells.

Defining a prognostic marker panel for patients with ovarian serous carcinoma effusion

Advanced-stage ovarian carcinoma is a highly lethal malignancy, yet no widely accepted prognostic panels exist to date in this disease. The objective of this study was to define such panel for patients with ovarian serous carcinoma effusions. The expression by immunohistochemistry and clinical role of 41 previously studied cancer-associated proteins was analyzed in 143 effusions from patients diagnosed as having advanced-stage (International Federation of Gynecology and Obstetrics stages III-IV) ovarian serous carcinoma treated with platinum-based chemotherapy at diagnosis. Survival analyses were performed separately for patients with prechemotherapy and postchemotherapy effusions. In univariate analysis of patients with primary diagnosis prechemotherapy effusions, survivin was associated with longer progression-free survival (P = .03), whereas survivin (P = .009), signal transducer and activator of transcription 5B (P = .011), and p21-activated kinase-1 (P = .04) were markers of longer overall survival. In univariate analysis of patients with disease recurrence postchemotherapy effusions, peroxisome proliferator-activated receptor-γ (P = .004), human leukocyte antigen-G (P = .013), mammalian target of rapamycin (P = .04), and nucleus accumbens 1 (NAC-1) (P = .046) were associated with poor progression-free survival, whereas peroxisome proliferator-activated receptor-γ (P = .013), claudin-3 (P = .019), activator protein-2γ (P = .04), insulin-like growth factor-2 (P = .04), claudin-7 (P = .042), and fatty acid synthase (P = .048) were markers of poor overall survival. In Cox multivariate analysis for prechemotherapy cases, survivin and fatty acid synthase were independent predictors of better progression-free survival (P = .006 and P = .048, respectively), and signal transducer and activator of transcription 5B and heat shock protein 90 were independently associated with better overall survival (P = .033 and P = .006, respectively). None of the biological markers was an independent prognostic factor in recurrent disease. The present study represents the first attempt at prognostic stratification of multiple tumor markers in one cohort of patients with ovarian serous carcinoma effusions.

Rsf-1, a chromatin remodelling protein, interacts with cyclin E1 and promotes tumour development

Chromosome 11q13.5 containing RSF1 (HBXAP), a gene involved in chromatin remodelling, is amplified in several human cancers including ovarian carcinoma. Our previous studies demonstrated requirement of Rsf-1 for cell survival in cancer cells, which contributed to tumour progression; however, its role in tumourigenesis has not yet been elucidated. In this study, we co-immunoprecipitated proteins with Rsf-1 followed by nanoelectrospray mass spectrometry and identified cyclin E1, besides SNF2H, as one of the major Rsf-1 interacting proteins. Like RSF1, CCNE1 is frequently amplified in ovarian cancer, and both Rsf-1 and cyclin E1 were found co-up-regulated in ovarian cancer tissues. Ectopic expression of Rsf-1 and cyclin E1 in non-tumourigenic TP53(mut) RK3E cells led to an increase in cellular proliferation and tumour formation by activating cyclin E1-associated kinase (CDK2). Tumourigenesis was not detected if either cyclin E1 or Rsf-1 was expressed, or they were expressed in a TP53(wt) background. Domain mapping showed that cyclin E1 interacted with the first 441 amino acids of Rsf-1. Ectopic expression of this truncated domain significantly suppressed G1/S-phase transition, cellular proliferation, and tumour formation of RK3E-p53(R175H) /Rsf-1/cyclin E1 cells. The above findings suggest that Rsf-1 interacts and collaborates with cyclin E1 in neoplastic transformation and TP53 mutations are a prerequisite for tumour-promoting functions of the RSF/cyclin E1 complex.

Rsf-1 overexpression correlates with poor prognosis and cell proliferation in colon cancer

Rsf-1 (HBXAP) was recently reported to be overexpressed in various cancers and associated with the malignant behavior of cancer cells. However, the expression of Rsf-1 and its biological roles in colon cancer have not been reported. The molecular mechanism of Rsf-1 in cancer aggressiveness remains ambiguous. In the present study, we analyzed the expression pattern of Rsf-1 in colon cancer tissues and found that Rsf-1 was overexpressed in 50.4 % of colon cancer specimens. There was a significant association between Rsf-1 overexpression and TNM stage (p = 0.0205), lymph node metastasis (p = 0.0025), and poor differentiation (p = 0.0235). Furthermore, Rsf-1 overexpression correlated with a poor prognosis in colon cancer patients (p = 0.0011). In addition, knockdown of Rsf-1 expression in HT29 and HCT116 cells with high endogenous Rsf-1 expression decrease cell proliferation and colony formation ability. Further analysis showed that Rsf-1 knockdown decreased cyclin E expression and phospho-Rb level. In conclusion, Rsf-1 is overexpressed in colon cancers and contributes to malignant cell growth by cyclin E and phospho-Rb modulation, which makes Rsf-1 a candidate therapeutic target in colon cancer.

The role of polymeric immunoglobulin receptor in inflammation-induced tumor metastasis of human hepatocellular carcinoma

Background

Expression of the polymeric immunoglobulin receptor (pIgR), a transporter of polymeric IgA and IgM, is commonly increased in response to viral or bacterial infections, linking innate and adaptive immunity. Abnormal expression of pIgR in cancer was also observed, but its clinical relevance remains uncertain.

Methods

A human hepatocellular carcinoma (HCC) tissue microarray (n = 254) was used to investigate the association between pIgR expression and early recurrence. An experimental lung metastasis model using severe combined immune-deficient mice was applied to determine the metastatic potential of Madin–Darby canine kidney (n = 5 mice per group) and SMMC-7721 (n = 12 mice per group) cells overexpressing pIgR vs control cells. RNA interference, immunoprecipitation, and immunoblotting were performed to investigate the potential role for pIgR in the induction of epithelial–mesenchymal transition (EMT). In vitro studies (co-immunoprecipitation, immunoblotting, and migration, invasion, and adhesion assays) were used to determine the mechanisms behind pIgR-mediated metastasis. All statistical tests were two-sided.

Results

High expression of pIgR was statistically significantly associated with early recurrence in early-stage HCC and in hepatitis B surface antigen–positive HCC patients (log-rank P = .02). Mice injected with pIgR-overexpressing cells had a statistically significantly higher number of lung metastases compared with respective control cells (Madin–Darby canine kidney cells: pIgR mean = 29.4 metastatic nodules per lung vs control mean = 0.0 metastatic nodules per lung, difference = 29.4 metastatic nodules per lung, 95% confidence interval = 13.0 to 45.8, P = .001; SMMC-7721 cells: pIgR mean = 10.4 metastatic nodules per lung vs control mean = 2.2 metastatic nodules per lung, difference = 8.2 metastatic nodules per lung, 95% confidence interval = 1.0 to 15.5, P = .03). Furthermore, high expression of pIgR was sufficient to induce EMT through activation of Smad signaling.

Conclusions

pIgR plays a role in the induction of EMT. Our results identify pIgR as a potential link between hepatitis B virus–derived hepatitis and HCC metastasis and provide evidence in support of pIgR as a prognostic biomarker for HCC and a potential therapeutic target.

Overexpression of a chromatin remodeling factor, RSF-1/HBXAP, correlates with aggressive oral squamous cell carcinoma

RSF-1, also known as hepatitis B X-antigen associated protein (HBXAP), is a subunit of an ISWI chromatin remodeling complex, remodeling and spacing factor (RSF). Recent studies have provided new evidence that chromatin remodeling participates in the pathogenesis of neoplastic diseases by altering cell cycle regulation and gene expression. In this report, we studied the biological roles of RSF-1 in oral squamous cell carcinoma (OSCC), a highly invasive neoplastic disease. Based on IHC and quantitative real-time PCR, we demonstrated that RSF-1 expression could be detected in the majority of OSCC cases, and the levels were significantly higher in OSCC cells than in their normal counterparts. Moreover, expression levels of RSF-1 significantly correlated with the presence of angiolymphatic invasion, abnormal mitoses, metastasis, tumor recurrence, and advanced stage disease at presentation. Univariate and multivariate analyses showed a significant association of RSF-1 overexpression and worse overall survival in OSCC patients. RSF-1 knockdown remarkably decreased cellular proliferation and induced apoptosis in OSCC cells with high RSF-1 expression levels, but not in those without. Taken together, our results suggest that RSF-1 up-regulation is associated with several clinicopathological features of disease aggressiveness in OSCC patients, and RSF-1 plays an important role in maintaining cellular growth and survival in OSCC.

Rsf-1, a chromatin remodeling protein, induces DNA damage and promotes genomic instability

Rsf-1 (HBXAP) has been reported as an amplified gene in human cancer, including the highly aggressive ovarian serous carcinoma. Rsf-1 protein interacts with SNF2H to form an ISWI chromatin remodeling complex, RSF. In this study, we investigated the functional role of Rsf-1 by observing phenotypes after expressing it in nontransformed cells. Acute expression of Rsf-1 resulted in DNA damage as evidenced by DNA strand breaks, nuclear γH2AX foci, and activation of the ATM-CHK2-p53-p21 pathway, leading to growth arrest and apoptosis. Deletion mutation and gene knockdown assays revealed that formation of a functional RSF complex with SNF2H was required for Rsf-1 to trigger DNA damage response (DDR). Gene knock-out of TP53 alleles, TP53 mutation, or treatment with an ATM inhibitor abolished up-regulation of p53 and p21 and prevented Rsf-1-induced growth arrest. Chronic induction of Rsf-1 expression resulted in chromosomal aberration and clonal selection for cells with c-myc amplification and CDKN2A/B deletion. Co-culture assays indicated Rsf-1-induced DDR as a selecting barrier that favored outgrowth of cell clones with a TP53 mutation. The above findings suggest that increased Rsf-1 expression and thus excessive RSF activity, which occurs in tumors harboring Rsf-1 amplification, can induce chromosomal instability likely through DDR.

Notch3 overexpression is related to the recurrence of ovarian cancer and confers resistance to carboplatin

Amplification of the Notch3 locus has been detected in ovarian high-grade serous carcinoma (HGSC), the most common and malignant type of ovarian cancer. We have previously demonstrated that ovarian cancer cells, which amplified and overexpressed Notch3, were dependent on Notch3 signaling for cellular survival and growth. In this study, we provide new evidence that Notch3 expression is associated with recurrent postchemotherapy HGSCs. Moreover, patients with recurrent HGSCs in effusion with high Notch3 expression had a significantly worse clinical outcome, including reduced overall survival and shortened progression-free survival than did patients with low Notch3 expressing HGSC. Ectopic expression of the Notch3 intracellular domain led to an increase in IC(50) for carboplatin in an ovarian surface epithelial cell line and in a low-grade serous carcinoma cell line that expressed undetectable levels of Notch3. Interestingly, expression of the Notch3 intracellular domain increased expression of several genes associated with embryonic stem cells including Nanog, Oct4, Klf4, Rex1, Rif1, Sall4, and NAC1 as well as an ATP-dependent transporter gene, ABCB1. Knockdown of Notch3 resulted in sensitization to carboplatin in OVCAR3 that expresses abundant Notch3. Taken together, the above findings suggest that Notch3 pathway activation reprograms tumor cells to assume an array of embryonic stem cell markers and participates in development of chemoresistance in HGSC.

Dendritic cells transduced with Rsf-1/HBXAP gene generate specific cytotoxic T lymphocytes against ovarian cancer in vitro

Recently, some studies have indicated that Rsf-1/HBXAP plays a role in chromatin remodeling and transcriptional regulation that may contribute to tumorigenesis in ovarian cancer. The present study demonstrates that using dendritic cells (DCs) from human cord blood CD34(+) cells transduced with Rsf-1/HBXAP DNA plasmids by nucleofection generate specific cytotoxic T lymphocytes (CTL) against ovarian cancer in vitro. After transfection, DCs were analyzed for Rsf-1/HBXAP mRNA expression by RT-PCR and protein expression by Western blot. Then the DC phenotypes, T-cell stimulatory capacity, endocytic activity and migration capacity were explored by flow cytometry analysis, allogeneic mixed lymphocyte reaction, endocytosis and transwell chemotaxis assay, respectively. After transfection, Rsf-1/HBXAP expression was detected at mRNA and protein levels. Allogeneic T-cell proliferation induced by transfected DCs was obviously higher than non-transfected DCs, but the endocytosis capacity and migratory ability were not different. Rsf-1/HBXAP gene-transduced DCs could induce antigen-specific CTL and generate a very potent cytotoxicity to OVCAR3 cells. These data suggest that Rsf-1/HBXAP gene-transduced DCs may be a potential adjuvant immunotherapy for ovarian cancer in clinical applications.

National Academy of Clinical Biochemistry Laboratory Medicine Practice Guidelines for Use of Tumor Markers in Testicular, Prostate, Colorectal, Breast, and Ovarian Cancers

Background: Updated National Academy of Clinical Biochemistry (NACB) Laboratory Medicine Practice Guidelines for the use of tumor markers in the clinic have been developed.

Methods: Published reports relevant to use of tumor markers for 5 cancer sites—testicular, prostate, colorectal, breast, and ovarian—were critically reviewed.

Results: For testicular cancer, α-fetoprotein, human chorionic gonadotropin, and lactate dehydrogenase are recommended for diagnosis/case finding, staging, prognosis determination, recurrence detection, and therapy monitoring. α-Fetoprotein is also recommended for differential diagnosis of nonseminomatous and seminomatous germ cell tumors. Prostate-specific antigen (PSA) is not recommended for prostate cancer screening, but may be used for detecting disease recurrence and monitoring therapy. Free PSA measurement data are useful for distinguishing malignant from benign prostatic disease when total PSA is &lt;10 μg/L. In colorectal cancer, carcinoembryonic antigen is recommended (with some caveats) for prognosis determination, postoperative surveillance, and therapy monitoring in advanced disease. Fecal occult blood testing may be used for screening asymptomatic adults 50 years or older. For breast cancer, estrogen and progesterone receptors are mandatory for predicting response to hormone therapy, human epidermal growth factor receptor-2 measurement is mandatory for predicting response to trastuzumab, and urokinase plasminogen activator/plasminogen activator inhibitor 1 may be used for determining prognosis in lymph node–negative patients. CA15-3/BR27–29 or carcinoembryonic antigen may be used for therapy monitoring in advanced disease. CA125 is recommended (with transvaginal ultrasound) for early detection of ovarian cancer in women at high risk for this disease. CA125 is also recommended for differential diagnosis of suspicious pelvic masses in postmenopausal women, as well as for detection of recurrence, monitoring of therapy, and determination of prognosis in women with ovarian cancer.

Conclusions: Implementation of these recommendations should encourage optimal use of tumor markers.

The roles of human sucrose nonfermenting protein 2 homologue in the tumor-promoting functions of Rsf-1

Rsf-1 interacts with human sucrose nonfermenting protein 2 homologue (hSNF2H) to form a chromatin remodeling complex that participates in several biological processes. We have previously shown that Rsf-1 gene amplification was associated with the most aggressive type of ovarian cancer and cancer cells with Rsf-1 overexpression depended on Rsf-1 to survive. In this report, we determine if formation of the Rsf-1/hSNF2H complex could be one of the mechanisms contributing to tumor cell survival and growth in ovarian carcinomas. Based on immunohistochemistry, we found that Rsf-1 and hSNF2H were co-upregulated in ovarian cancer tissues. Ectopic expression of Rsf-1 in SKOV3 ovarian cancer cells with undetectable endogenous Rsf-1 expression enhanced hSNF2H protein levels and promoted SKOV3 tumor growth in a mouse xenograft model. Our studies also indicated that induction of Rsf-1 expression affected the molecular partnership of hSNF2H and translocated hSNF2H into nuclei where it colocalized with Rsf-1. Furthermore, analysis of Rsf-1 deletion mutants showed that the Rsf-D4 fragment contained the hSNF2H binding site based on coimmunoprecipitation and in vitro competition assays. As compared with other truncated mutants, expression of Rsf-D4 resulted in remarkable growth inhibition in ovarian cancer cells with Rsf-1 gene amplification and overexpression, but not in those without detectable Rsf-1 expression. The above findings suggest that interaction between Rsf-1 and hSNF2H may define a survival signal in those tumors overexpressing Rsf-1.

Different clinical roles for p21-activated kinase-1 in primary and recurrent ovarian carcinoma

We recently found amplification of chromosome 11q13.5 in high-grade ovarian serous carcinoma. In the present study, we analyzed the protein expression and clinical significance of p21-activated kinase-1, one of the genes amplified at this site. Formalin-fixed paraffin-embedded sections from 186 effusions (152 peritoneal, 34 pleural) were immunostained. p21-Activated kinase-1 expression in tumor cells was analyzed for possible association with clinicopathologic parameters and survival. The association between protein expression of p21-activated kinase-1 and Rsf-1, a chromatin remodeling protein whose gene colocalizes with p21-activated kinase-1, was additionally studied. p21-Activated kinase-1 protein expression was found in carcinoma cells in 158 (85%) of 186 effusions. Of these, 62 (39%) stained weakly and 96 (61%) strongly. p21-Activated kinase-1 was coexpressed with Rsf-1 (P = .006). Specimens from patients diagnosed with International Federation of Gynecology and Obstetrics stage IV disease had higher staining intensity compared with stage III tumors (P = .014). Univariate survival analysis for patients with primary diagnosis prechemotherapy effusions demonstrated a significant association between higher p21-activated kinase-1 staining extent and longer overall survival (P = .024). In addition, higher staining extent (P = .015) and intensity (P = .013) correlated with better progression-free survival. In contrast, higher p21-activated kinase-1 staining extent correlated with poor overall survival in disease recurrence postchemotherapy effusions (P = .044). In Cox analysis, higher p21-activated kinase-1 staining extent independently correlated with longer progression-free survival (P = .016) and shorter overall survival (.049) in primary diagnosis and disease recurrence effusions, respectively. p21-Activated kinase-1 is frequently expressed in ovarian carcinoma cells in effusions and is associated with opposite prognostic role in primary and recurrent disease. This suggests altered cellular function for this kinase along disease progression, possibly chemotherapy mediated.

Expression of the chromatin remodeling factor Rsf-1 is down-regulated in breast carcinoma effusions

We recently identified Rsf-1, a chromatin-remodeling gene, as a potential oncogene that is frequently amplified and overexpressed in ovarian serous carcinoma, and demonstrated that its expression in carcinoma cells in effusions is associated with poor prognosis. In the present study, we assessed the clinical significance of Rsf-1 overexpression in breast carcinoma effusions. Formalin-fixed paraffin-embedded sections from 47 effusions were analyzed for Rsf-1 expression by immunohistochemistry. Matched primary tumors (n = 30) and solid metastases (n = 26) from 30 patients were additionally studied. Rsf-1 expression in tumor cells in effusions was analyzed for association with clinicopathologic parameters and survival. Rsf-1 protein expression was found in carcinoma cells in 34 (72%) of 47 effusions, 24 (80%) of 30 primary carcinomas, and 24 (92%) of 26 metastases. Rsf-1 immunoreactivity in effusions showed no association with HER-2 or hormone receptor status. Rsf-1 expression level was significantly lower in effusions compared with primary tumors (P = .026 and P = .011 for extent and intensity, respectively) and lymph node metastases (P = .023 and P = .013 for extent and intensity, respectively). Staining extent and intensity were both significantly lower in breast compared with ovarian carcinoma effusions (P = .001 for extent, P < .001 for intensity). Rsf-1 expression showed no association with survival. In conclusion, in contrast to ovarian carcinoma, Rsf-1 expression is down-regulated in breast carcinoma cells in effusions compared with the solid counterparts and has no prognostic role at this anatomic site.

Immunohistochemistry of choriocarcinoma: an aid in differential diagnosis and in elucidating pathogenesis

Choriocarcinoma is traditionally described as being composed of cytotrophoblast and syncytiotrophoblast. Microscopically, these 2 types of cells are intimately associated with each other, forming a characteristic biphasic plexiform pattern, however, the nature of these 2 types of trophoblastic cells is not well understood. In this study, we used immunohistochemistry for several trophoblastic markers to analyze the trophoblastic subpopulations in 36 gestational choriocarcinomas. Eighty-one specimens including placenta, complete mole, placental site nodule, epithelioid trophoblastic tumor, and placental site trophoblastic tumor were analyzed. The antibodies included Mel-CAM, HLA-G, MUC-4, and beta-catenin. A semiquantitative assessment of positive cells and the cellular localization of these markers were recorded. We found diffuse strong membranous and cytoplasmic staining for MUC-4 in mononucleate cells in all 36 cases (100%) and a similar pattern of localization in 28 cases (78%) for HLA-G. This distribution was similar to that in normal placentas, where MUC-4 and HLA-G are expressed in the trophoblastic cells of the trophoblastic columns and implantation site. In choriocarcinoma, mononucleate trophoblastic cells showed moderate immunoreactivity for Mel-CAM, a specific marker for implantation site intermediate trophoblast, in 78% of the cases. The MUC-4, HLA-G, and Mel-CAM-positive trophoblastic cells were larger than cytotrophoblastic cells, with more abundant cytoplasm, consistent with the morphology of intermediate trophoblast. In contrast, 31% of the choriocarcinomas contained a very small proportion (<5%) of mononucleate trophoblastic cells compatible with cytotrophoblast that was positive for nuclear beta-catenin, a cytotrophoblast-associated marker. These results suggest that choriocarcinoma is composed predominantly of a mixture of syncytiotrophoblast and intermediate trophoblast with only a small proportion of cytotrophoblast. The presence of nuclear beta-catenin staining in the cytotrophoblast of choriocarcinoma is consistent with the view that choriocarcinoma develops from transformed cytotrophoblastic cells which are presumably the cancer stem cells that differentiate into either intermediate trophoblast or syncytiotrophoblast.

Low-molecular weight forms of cyclin E differentiate ovarian carcinoma from cells of mesothelial origin and are associated with poor survival in ovarian carcinoma

BACKGROUND

The authors recently reported on the role of cyclin E in differentiating ovarian/primary peritoneal carcinoma from malignant peritoneal mesothelioma using gene expression arrays. In the current study, they analyzed the expression of low-molecular weight (LMW) forms of cyclin E in ovarian carcinoma, malignant mesothelioma, and benign reactive effusions.

METHODS

Cyclin E protein expression was analyzed in 98 effusions (72 ovarian carcinomas, 14 malignant mesotheliomas, and 12 reactive specimens) using immunoblotting. Sixty-two ovarian carcinoma effusions were studied further for cyclin E expression using immunohistochemistry. The correlations between cyclin E expression in ovarian carcinoma and clinical parameters, including chemotherapy response, were analyzed.

RESULTS

LMW forms of cyclin E were identified in 54 of 72 ovarian carcinoma effusions (75%) compared with 1 of 14 malignant mesothelioma effusions (7%) and 1 of 12 reactive effusions (8%) (P < .001). Their presence in ovarian carcinoma was associated with a higher percentage of cyclin E-positive cells (P = .001) and increased staining intensity (P < .001) using immunohistochemistry. The presence of LMW forms of cyclin E was correlated with shorter overall survival (P = .021) and progression-free survival (P = .020). The presence of a higher percentage of cyclin E-positive cells using immunohistochemistry was correlated with shorter progression-free survival (P = .026). No association with chemotherapy response was observed.

CONCLUSIONS

LMW forms of cyclin E differentiated ovarian carcinoma from benign and malignant mesothelial cells and were associated with increased protein expression using immunohistochemistry. The expression of LMW cyclin E forms was not associated with chemotherapy response, although it may be a marker of aggressive disease in patients with metastatic ovarian carcinoma.

Expression and clinical role of the bric-a-brac tramtrack broad complex/poxvirus and zinc protein NAC-1 in ovarian carcinoma effusions

We recently identified NAC-1, member of the bric-a-brac tramtrack broad complex/poxvirus and zinc domain family, as an overexpressed gene in ovarian serous carcinoma and found more frequent NAC-1 protein expression in recurrent compared to primary tumors. In the present study, we assessed the clinical significance of NAC-1 expression in ovarian carcinoma effusions. Formalin-fixed, paraffin-embedded sections from 176 effusions (137 peritoneal, 39 pleural) and 197 corresponding solid tumors (69 primary tumors, 128 solid metastases) were analyzed for NAC-1 expression using immunohistochemistry. Staining intensity and extent results were analyzed for possible association with clinicopathologic parameters and survival. Nuclear NAC-1 immunoreactivity was found in carcinoma cells in 98% of (173/176) effusions, 94% (65/69) of primary tumors, and 95% (121/128) of metastases. Staining intensity and extent were significantly higher in effusions compared with matched solid tumors (P = .002 for intensity, P = .003 for extent compared with primary tumors; P < .001 for both intensity and extent compared with metastases). Furthermore, NAC-1 expression intensity was significantly higher in specimens obtained after the administration of chemotherapy (P = .002) and correlated with shorter progression-free survival (PFS) in analysis of 62 patients with post-chemotherapy effusions (P = .039). International Federation of Gynecology and Obstetrics stage (IV versus III) was the only clinical parameter associated with PFS in this group (P = .004). In Cox analysis, only the International Federation of Gynecology and Obstetrics stage was an independent predictor of shorter PFS (P = .009). In conclusion, NAC-1 expression is higher in ovarian carcinoma cells in effusions compared with their solid tumor counterparts. NAC-1 is up-regulated in tumor cells after chemotherapy, suggesting a role for this protein in tumor progression and in the development of chemotherapy resistance in ovarian cancer.