BAP1, Wilms' tumor 1, and calretinin in predicting survival and response to first-line chemotherapy in patients with pleural mesothelioma

PURPOSE

There are currently no methods to predict response to chemotherapy in pleural mesothelioma (PM). The aim of this study is to investigate the predictive and prognostic role of BAP1, WT1 and calretinin expression and their combinations in pre-treatment tumor samples by immunohistochemical (IHC) staining.

METHODS

The study included consecutive PM patients treated with chemotherapy alone at a University hospital between 2009 and 2020. BAP1 analyses were performed on formalin-fixed, paraffin-embedded tumor tissue samples of the patients, while WT1 and calretinin information were obtained from the histopathological diagnosis records.

RESULTS

Of the total 107 patients included, 64% had loss of BAP1 expression, whereas 77% had WT1 and 86% had calretinin expression. Patients with the presence of BAP1 expression, one or both of the other two markers, or loss of expression of all three markers (unfavorable status) were more likely to not respond to chemotherapy than those with the presence of all three markers or loss of BAP1 expression and expression of one or two other markers (favorable status) (p = 0.001). Median survival time of patients with favorable and unfavorable status was 15 ± 1.7 and 8.0 ± 2.4 months, respectively (p = 0.027). After adjustment for histopathology and stage, loss of BAP1 (HR = 0.54, 95%CI 0.35-0.83), WT1 (1.75, 1.06-2.90), calretinin (2.09, 1.14-3.84) expression and favourable panel (0.50, 0.27-0.92) was associated with prognosis.

CONCLUSIONS

The IHC biomarkers BAP1, WT1, and calretinin, used in the routine diagnosis of PM and their combinations, are the first biomarkers associated with response to chemotherapy and may be a useful tool to select patients for first-line platinum pemetrexed treatment in PM patients. Validation in a large cohort is ongoing.

Wilms' tumor gene 1 is an independent prognostic factor for pediatric acute myeloid leukemia following allogeneic hematopoietic stem cell transplantation

BACKGROUND

Sequential monitoring of Wilms' tumor gene 1 (WT1) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) could predict relapse in adult acute myeloid leukemia (AML). However, the prognostic role of WT1 in pediatric AML after allo-HSCT is unclear. Thus, we determined to see whether sequential monitoring of WT1 after allo-HSCT could predict relapse in AML children.

METHODS

Pediatric AML patients receiving allo-HSCT from January 21, 2012 to December 20, 2018 at the Peking University Institute of Hematology were included in this study. WT1 expression level was determined by TaqMan-based reverse transcription-polymerase chain reaction. WT1 sequential monitoring was performed 1, 2, 3, 4.5, 6, 9, and 12 months post-transplantation and at 6-month intervals thereafter. The primary end point was relapse. The secondary end points included disease-free survival (DFS), overall survival (OS), and non-relapse mortality (NRM). Kaplan-Meier analysis was used for DFS and OS estimates, while competing risk analysis was used for estimating relapse and NRM.

RESULTS

Of the 151 consecutive patients included, the median age was 10 years (range, 1-17). The optimal cutoff value of WT1 within 1 year after allo-HSCT to predict relapse was 0.8% (80 WT1 copies/104 ABL copies), with a sensitivity of 60% and specificity of 79%. Compared with WT1 expression < 0.8%, WT1 expression ≥0.8% indicated significantly higher 5-year cumulative incidence of relapse (CIR, 35.1% vs. 11.3%; P = 0.001), lower 5-year disease-free survival (DFS, 60.4% vs. 80.8%; P = 0.009), and lower 5-year overall survival (OS, 64.9% vs. 81.6%; P = 0.038) rates. Multivariate analyses showed that WT1 was an independent risk factor for relapse (HR 2.89; 95% confidence interval (CI), 1.25-6.71; P = 0.014). Both the CIR (5-year CIR: 8.3% vs. 11.3%; P = 0.513) and DFS (5-year DFS: 91.7% vs. 80.8%; P = 0.208) were comparable between patients achieving minimal residual disease (MRD) negativity after preemptive interferon-α (IFN-α) treatment and those without MRD after allo-HSCT, which were better than those of MRD-positive patients without preemptive therapies.

CONCLUSIONS

Sequential monitoring of WT1 could predict relapse in pediatric AML after allo-HSCT. WT1-directed immunotherapy may have the potential to prevent relapse and improve survival.

Podocyte Involvement in Renal Thrombotic Microangiopathy: A Clinicopathological Study

BACKGROUND

The current study aimed to evaluate the associations between podocyte injury and clinicopathological features in renal thrombotic microangiopathy (TMA) based on a Chinese cohort, which might be underscored in this disease.

METHODS

The clinical, laboratory, and renal histopathological data of patients with renal biopsy-proven TMA from 2000 to 2015 in our institute were collected. Foot process effacement (FPE) was quantified by foot process width (FPW) by electron microscopy. Podocytes in the renal specimens were also detected by stainings for podocyte-specific markers, including Wilms tumor 1 (WT-1), synaptopodin, and podocalyxin. The associations between FPW and clinico-histopathological data were further analyzed. A composite end-point was defined by all-cause death or end-stage renal disease to address the predictive value of FPW.

RESULTS

Sixty-three patients with renal biopsy-proven TMA were enrolled. The FPW of renal TMA patients was 1,090 ± 637 nm (range, 572-4,748 nm), which was significantly higher than the normal range in our center (p = 0.005). By immunohistochemistry and immunofluorescence assays, we found decreased expressions of synaptopodin, podocalyxin, and WT-1 and continued stainings of WT-1 in some podocytes without detectable synaptopodin stainings in the areas of sclerotic tufts and cellular crescents. The FPW value was correlated with the serum albumin concentration (rs = -0.281, p = 0.026), proteinuria amount (rs = 0.255, p = 0.047), serum creatinine levels (rs = 0.339, p = 0.007), and eGFR (rs = -0.335, p = 0.007). According to ROC curve analysis, the optimal cutoff level of FPW for predicting the composite end-point was 869 nm. In patients with FPW ≥ 869 nm, FPW levels were further correlated with the severity of mesangiolysis (rs = 0.351, p = 0.033) and glomerulosclerosis (rs = 0.369, p = 0.025) in pathological evaluations. Patients without clinical remission also had higher FPW than those with remission (1,240 ± 793 vs. 925 ± 344 nm, p = 0.013). The multivariate Cox hazard model showed that FPW ≥ 869 nm was an independent risk factor for the composite end-point (hazard ratio: 3.64, 95% CI: 1.37-9.66, p = 0.009).

CONCLUSION

The podocyte injury was prevalent and the FPW levels were closely associated with clinicopathological features, especially prognosis, in renal TMA patients.

Sarcomatoid Type of Paratesticular Malignant Mesothelioma in a Dry-Cleaning Worker Exposed to Asbestos and Diagnostic Value of WT-1

Of the 3 major histologic types of malignant paratesticular mesothelioma (MPM) (epithelial, sarcomatoid, and biphasic), many cases of epithelial and biphasic mesothelioma have been reported in the literature. Pure sarcomatoid MPM is the least common but the most aggressive of the 3 major histologic types of mesothelioma cells. It is limited to only 2 cases in the literature The sarcomatoid type of MPM can be confused clinically and histologically with true sarcomas because it is rarely seen. We present a case who had been exposed to asbestos for years due to his involvement in the dry-cleaning industry and who was diagnosed with the sarcomatoid type of MPM but had a relatively prolonged survival not usually seen with this tumor. This report also emphasizes the significance of an immunohistochemical examination, focusing especially on the diagnostic role of WT-1.

MORPHOPHENOTYPIC CHARACTERISTICS OF OVARIAN SEROUS BORDERLINE TUMORS

Borderline ovarian tumors (BOTs) represent particular challenge for diagnosis and clinical management as they are characterized with the features of both benign cystadenomas and malignant carcinomas. The aim of our study was to investigate histomorphological and immunohistochemical characteristics of ovarian serous-papillary borderline tumors, compared to serous cystadenomas and low- and high-grade serous carcinomas. Altogether, 80 formalin fixed and paraffin embedded tissue specimens, distributed in four groups, including serous cystadenoma (group I), serous BOTs (group II), Low (group III) and high (group IV) grade serous carcinomas, were investigated by standard immunohistochemistry, using antibodies against CK7 CK20, WT1, Vimentin, CDX2, CEA, ER, cyclin D1, BCL2, E-cadherin, calretinin, СA125, Ki67, P53. Study results showed, that ovarian serous BOTs are characterized with slightly increase proliferative potential compared to benign cystadenomas, whilst apoptotic potential is retained with the difference from malignant serous carcinomas. p53 mutation is not present, as well as the expression of Vimentin. Overall, ovarian serous BOTs are characterized with highly variable immunohistochemical phenotype and the use of multiple immunohistochemical markers are recommended for the differential diagnosis from low grade serous carcinomas and benign cystadenomas.

Protective effect of calcitriol on podocytes in spontaneously hypertensive rat

BACKGROUND

Hypertension is a major global public health issue. Uncontrolled hypertension leads to organ damage, especially renal damage. Calcitriol is used to treat osteoporosis, promote bone formation, and increase bone mass. Previous studies have demonstrated that 1,25(OH)2D3, in addition to its classic role, also has multiple immune regulation and renoprotective functions and inhibits the activity of the renin-angiotensin-aldosterone system (RASS). The aim of the current study was to investigate the renoprotective effects of calcitriol in a spontaneously hypertensive rat (SHR) model.

METHODS

A total of 18 SHRs and 8 age-matched normal Wistar rats were enrolled. SHRs were randomly divided into a hypertensive nephropathy group (H), a hypertensive nephropathy treated with calcitriol group (D) and a control group (NS). The rats were sacrificed after 16 weeks of treatment. The blood pressure (BP) of rats were measured one time every 4 weeks. The levels of serum albumin, serum creatinine, blood calcium, serum Vitamin D and 24-h urinary protein were measured after 16 weeks treatment. The protein level of WT1, nephrin and vitamin D receptor (VDR) was examined by Western blotting and immunohistochemical staining.

RESULTS

There were no notable changes in blood pressure or serum creatinine in group H and D compared with group NS. The albumin, calcium and vitamin D serum levels in group H were significantly decreased compared with group NS and significantly increased in group D compared with group H. The level of 24-h urine protein significantly increased in group H compared with group NS and significantly decreased in group D compared with group H. The expression of VDR, WT1 and nephrin in the kidney were all significantly decreased in group H compared with group NS and significantly increased in group D compared with group H.

CONCLUSION

The present results indicated that there was injury of podocytes in hypertensive nephropathy, which can be ameliorated by calcitriol in SHR, but there was no significant anti-hypertensive effect. Vitamin D/VDR decreased proteinuria perhaps by increasing expression of nephrin and WT1 protein in podocyte of SHRs.

A comparison of p53 and WT1 immunohistochemical expression patterns in tubo-ovarian high-grade serous carcinoma before and after neoadjuvant chemotherapy

AIMS

The treatment of patients with tubo-ovarian high-grade serous carcinoma (HGSC) is increasingly based on diagnosis on small biopsy samples, and the first surgical sample is often taken post-chemotherapy. p53 and WT1 are important diagnostic markers for HGSC. The effect of neoadjuvant chemotherapy on p53 and WT1 expression has not been widely studied. We aimed to compare p53 and WT1 expression in paired pre-chemotherapy and post-chemotherapy samples of HGSC.

METHODS AND RESULTS

Immunohistochemistry (IHC) was carried out for p53 and WT1 on paired omental HGSC samples pre-chemotherapy and post-chemotherapy. p53 IHC was recorded as normal (wild-type) or abnormal (mutation-type), and was further classified as overexpression, complete absence, or cytoplasmic. WT1 IHC was classified as positive or negative. A subset of cases were further assessed for the extent of nuclear immunoreactivity of WT1 by use of the H-score. Fifty-seven paired samples were stained with p53. Fifty-six of 57 (98%) cases showed mutation-type p53 staining. Pre-chemotherapy and post-chemotherapy IHC results were concordant in 55 of 57 (96%) cases. For WT1, pre-chemotherapy and post-chemotherapy IHC results were concordant in 56 of 58 (97%) cases. In 23 paired WT1 cases, the mean post-treatment H-score decreased from 227 [range 20-298, standard deviation (SD) 64] to 151 (range 0-288, SD 78) (P = 0.0008).

CONCLUSIONS

Immunohistochemical expression of p53 (abnormal/mutation-type pattern) and WT1 in HGSC is almost universal and is largely concordant before and after chemotherapy. This finding underscores the reliability of these diagnostic markers in small samples and in surgical samples following neoadjuvant chemotherapy, with very few exceptions. A novel finding was the significant diminution in intensity of WT1 staining following chemotherapy.

Expression of Cell Membrane Antigens in Cells Excreted in the Urinary Sediment Predicts Progression of Renal Disease in Patients with Focal Segmental Glomerulosclerosis

BACKGROUND/AIMS

A link between the number of podocytes excreted in the urine and activity of glomerular disease has been established. The aim of this study was to investigate possible correlations between urinary cells' phenotype and the progression of focal segmental glomerulosclerosis (FSGS).

METHODS

Forty patients with newly diagnosed FSGS were included. Cells were isolated from urine by adherence to collagen-coated cover slips and assessed for the expression of podocalyxin (PDX), CD68 and Ki67 antigens by indirect immunofluorescence. In addition, double-staining procedures were performed in combinations of the above antigens plus cytokeratin, WT1 and CD-105. Twenty-two patients in whom urinary protein to creatinine ratio exceeded 2.0 at diagnosis were followed for 36 months, with assessments of renal function and proteinuria every 3 months. During observation, patients were subjected to standard therapy.

RESULTS

Significantly higher numbers of Ki67 positive cells at the onset of the study were observed in patients who have doubled serum creatinine (SCr) in follow-up, than in those who have not (p = 0.0149). By logistic regression analysis, both CD68 and Ki67, but not anti-PDX positive cell numbers at diagnosis were found to be predictors of doubling SCr concentration in 36 months' follow-up. Results of double staining indicate that PDX positive cells could be identified as podocytes or their precursors and parietal epithelial cells.

CONCLUSION

Urinary sediment PDX positive cell numbers do not predict the progression of FSGS, whereas CD68 and Ki67 phenotype of urinary podocytic lineage clearly has a prognostic significance in 36 months' observation of primary FSGS.

The expression and significance of WT1 in xenotransplanted ovarian carcinoma treated by paclitaxel

In this study, the authors investigated the expression and significance of WTl in xenotransplanted ovarian carcinoma cell SKOV3 of nude mice treated with paclitaxel. Xenotransplanted ovarian carcinoma was established in nude mice using the SKOV3 cell line. The mice were randomized into the treatment group with paclitaxel and control group with normal sodium. The sizes of the xenotransplanted tumors were measured and the tumor specimens were confirmed by routine hemotoxylin-eosin (H&E) staining. The apoptosis index was then assayed using flow cytometry. WTl and bcl-2 expression were detected with immunohistochemistry, and WT1 mRNA expression was determined by reverse transcriptase polymerase chain reaction (RT-PCR). The authors found that the growth of the xenotransplanted tumor was inhibited by paclitaxel therapy. Compared to the control group, the apoptosis rate was significantly increased in the treatment group (p < 0.05). At the same time, the expression of WTl, bcl-2 and WTI, mRNA were significantly decreased in the paclitaxel therapy group (p < 0.05). The authors conclude that the WTl gene may play an important role during apoptosis of ovarian carcinoma and the mechanism may be closely related to bcl-2.

Distinctive immunohistochemical staining in littoral cell angioma using ERG and WT-1

Littoral cell angioma (LCA) is a rare vascular tumor of the spleen. It has an immunohistochemical staining pattern that is somewhat distinctive but can still be occasionally confused with other vascular and stromal proliferations in the spleen. In this study, LCA was evaluated using Ets-related gene (ERG) and Wilms tumor-1 (WT-1), relatively recently described vascular markers. In addition, other vascular lesions including normal spleen, hemangiomas, hamartoma, peliosis, and sclerosing angiomatoid nodular transformation were evaluated using these stains. In LCA, ERG stains the endothelial cells of the tumor as expected. ERG also was uniformly positive in vascular elements of other lesions except peliosis. However, in contrast to most other vascular elements, LCA was negative for WT-1 staining. This staining pattern may prove useful in diagnosing LCA and may provide insight into the derivation of the distinctive tumor.

Diagnostic utility of WT-1 cytoplasmic stain in variety of vascular lesions

Vascular lesions are commonly encountered in routine pathologic practice and often pose diagnostic challenges owing to their morphologic diversity. Although WT-1 expression was reported in some vascular tumors, little is known about its staining patterns in a spectrum of vascular lesions from various locations. We examined WT-1 immunostain in 95 cases of vascular lesions including angiosarcomas (AS, 19 cases), hemangioendotheliomas (HE, 5), Kaposi's sarcomas (KS, 4), cavernous hemangiomas (CVH, 12), capillary hemangiomas (CPH, 7), pyogenic granulomas (PG, 4), lymphangiomas (LA, 4), hemangiopericytomas (HP, 5), glomus tumors (GT, 8), vascular malformation (VM, 13) and granulation tissue (GRT, 14). Strong WT-1 cytoplasmic stain was invariably observed in all cases of malignant and borderline vascular tumors including AS (19/19), KS (4/4) and HE (5/5). WT-1 was also consistently expressed in CPH (7/7), PG (4/4), and GRT (14/14), while it became weaker in VM (10/13) and often negative in CVH (2/12) and LA (0/4). WT1 stain was not demonstrated in HP (0/5) and rarely in GT (2/8). We conclude that consistent and diffuse WT-1 cytoplasmic stain in AS, HE and KS can be useful in distinguishing these tumors from poorly differentiated tumors with mimicking features. On the other hand, reliable WT-1 stain in CPH, PG and GRT may help in differential diagnosis with non-endothelial vascular tumors such as GT and HP. Recognizing the WT-1 cytoplasmic stain in a broad spectrum of benign and neoplastic tissues is critical in formulating appropriate immunohistochemical panels and avoiding misinterpretation of results.

The significance of Wilms Tumor Gene (WT1) and p53 expression in curettage specimens of patients with endometrial carcinomas

In this retrospective experimental study, we assessed the immunohistochemical expression of Wilms Tumor Gene (WT1) and p53 in endometrial biopsies of patients with endometrial cancer, and correlated their expression with the final pathological findings. Sixty-two patients with primary endometrial cancer who underwent surgical treatment were investigated. Immunohistochemical expression of Wilms Tumor Gene (WT1) and p53 was assessed in curettage specimens, and the final pathology reports from hysterectomy specimens were reviewed. The expression of these markers seems to play a role in curettage specimens as they correlate with the final tumor characteristics of hysterectomy specimens. Five out of sixty-two endometrial cancer specimens (8.1%) were WT1-positive, and 21 specimens (33.9%) were P53-positive. Positive expression of WT1 and P53 was significantly associated with the non-endometrioid type (p value of 0.019 and 0.005, respectively). Positive WT1 expression was significantly associated with high grade lesions, deep myometrial invasion, and advanced stage disease. Moreover, a statistically significant inverse relationship was observed between the positivity of WT1 and P53, and the positivity of ER and PR. We think that examination for WT1 and p53 in curettage specimens might help to predict the final pathological diagnosis in patients with endometrial cancer. This might be useful for the identification of high risk groups and, therefore, of candidates for more radical surgery.

HIF-1α, VEGF and WT-1 are protagonists in bilateral primary angiosarcoma of breast: a case report and review of literature

Bilateral primary angiosarcoma of breast is an extremely rare disease. Only 4 cases had been described in the literature. Hypoxia inducible factor- 1 α (HIF-1α) is a transcription factor that binds to hypoxia response elements in the promoters of target genes. Vascular endothelial growth factor (VEGF) is an important signaling protein involved in angiogenesis. Wilms tumor -1 protein (WT-1) is a transcription factor that plays an important role in angiogenesis. We present a 29-year old female with bilateral primary angiosarcoma of breast. Five-μm sections were stained with CD31, FLI-1, HIF-1α, WT-1, VEGF, VEGF-R, D2-40, estrogen receptor, and progesterone receptor. The neoplastic cells show diffuse immunoreactivity to CD31, FLI-1, HIF- 1α, VEGF, VEGFR, and WT-1 protein. The neoplastic cells show no immunoreactivity to estrogen receptor, progesterone receptor and D2-40. In conclusion, HIF- 1α, WT-1 and VEGF are possible protagonists in the development of bilateral primary angiosarcoma of breast. The neoplastic process involves endothelial cell of blood vessels lineage rather than lymphatic lineage. Painless breast tumors in young women that are highly vascular at the time of biopsy should be considered as malignant until proven otherwise. Tissue biopsy is the gold standard in the diagnosis of primary angiosarcoma of breast.

Accuracy of immunohistochemistry in evaluation of malignant pleural and peritoneal effusions

BACKGROUND

The aim was to evaluate the accuracy of immunohistochemistry in diagnosis of the source of malignancies in pleural and peritoneal fluids in comparison to histopathology as the gold standard.

MATERIAL AND METHODS

Retrospectively, the cell block specimen and past medical data files of patients who had undergone serosal fluid aspiration and had a histopathology report corresponding to underlying disease were retrieved. Three mesothelial antibodies (D2-40, calretinin and WT-1) and two non-mesothelial antibodies (MOC-31 and EMA) were set to be applied for evaluating malignant cells and benign cells within serous fluids.

RESULTS

Seventy-one patients, 12 men and 59 women, were found to have a thorough information package needed, including cell blocks with appropriate cellularity on which ICC was applicable and the corresponding histopathology report. As mesothelial markers, calretinin and WT-1 were found to have sensitivity and specificity of 90%, 96.7% and 100%, 42.6%, respectively. Sensitivity and specificity of D2-40 both reached 100%. In addition, as non-mesothelial markers, MOC-31 and EMA were demonstrated to have sensitivity and specificity of 95.08%, 90% and 93.4%, 70%, respectively.

CONCLUSION

D2-40 was reconfirmed to act as an accurate marker in distinguishing between cells of mesothelial and non-mesothelial origin. However, WT-1 is not specific enough to be considered as accurate as D2-40. Considering the sensitivity and specificity of calretinin and MOC-31, they can be considered as safe but not as much as D2-40. EMA is not recommended as an ancillary marker due to its low specificity and challenging results.

[Biological markers for diagnosis of myeloid leukemia]

There are several important biological markers in myeloid leukemia. In particular, WT1, FLT3, P-glycoprotein (P-gp) and surface antigens are important biologic markers. When we monitor the treatment of leukemia, WT1 is considered to be an important marker, and has been applied to immune therapy. The abnormality of the genes of FLT3 and expression of P-gp are poor prognostic factors, and their inhibitors are developed in progress. The surface antigen analysis of blast cells is also used in the classification and the treatment strategy decision. Recently, as for the treatment of leukemia, stratification by various kinds of factors has been adopted in many prospective studies. The results of these biological markers are utilized for the stratification.

Fine needle aspiration biopsy of metanephric adenoma: a case report

BACKGROUND

Metanephric adenoma (MA) is a rare, benign renal neoplasm. Only 3 previous case reports describe the fine needle aspiration biopsy (FNAB) cytologic features of MA. Regarding treatment, radioflrequency ablation (RFA) is an emerging alternative to surgical resection of renal neoplasms in appropriately selected patients.

CASE

A 49-year-old woman had a 3.3-cm cortical mass in the left kidney. Computed tomography-guided FNAB was performed, followed by RFA of the lesion. The aspirate smears displayed multiple aggregates of benign-appearing, tightly packed and overlapping nuclei surrounded by basement membrane- type material. The cohesive aggregates were arranged in tubular or tubulopapillary structures without fibrovascular cores. No atypia, mitotic figures or necrosis were present. Immunohistochemical (IHC) stains performed displayed positive staining for WT-1, CD57 and cytokeratin AE1/AE3 and equivocal staining for CD56. The AMACR, CK7 and EMA immunostains were negative. Although the differential diagnosis included adult Wilms' tumor and papillary renal cell carcinoma, the bland morphology and IHC staining pattern strongly favored a neoplasm consistent with MA.

CONCLUSION

FNAB can be used to diagnose most renal neoplasms. A diagnosis of MA can be suggested on FNAB in the context of appropriate cytomorphology, IHC staining and cytogenetic analysis.

[Metanephric adenoma: report of two cases]

We report 2 cases of metanephric adenoma a rare form of adenoma. One case occurred in a 54-year-old male preoperatively diagnosed with renal cell carcinoma who underwent left partial nephrectomy for a tumor 2 cm in size. Histology revealed a tumor with papillotubular structures consisting of small, uniform tumor cells. In immunohistochemical staining, tumor cells were positive for CD57 and WT-1. Thus, the patient was diagnosed with metanephric adenoma. The other case occurred in a 40-year-old male who underwent left nephroureterectomy for carcinoma of the renal pelvis. Carcinoma of the left renal pelvis was diagnosed as pT3N0M0. Incidental micronodules 2 mm in size and consisting of immature tubular structures were noted in the renal cortex. In immunohistochemical staining, tumor cells were positive for CD57 and WT-1, and the patient was diagnosed with metanephric adenoma. The aforementioned tumors frequently occur in middle-aged women and are often well-defined tumors that project from the renal surface outwards. On angiography, they have a hypovascular pattern and resemble papillary renal carcinoma. Preoperative differentiation of renal cell carcinoma and nephroblastoma is difficult. Mistaking such tumors for malignant tumors and subjecting patients to unnecessary adjuvant therapy must be avoided.

WT1 protein expression in childhood acute leukemia

In patients with acute leukemia, Wilms' tumor gene 1 (WT1) has been used as a target for the detection of minimal residual disease (MRD) by PCR techniques. The expression of WT1 protein, however, has not been extensively studied. To determine the relation between expression of WT1 transcripts and of the encoded protein, we examined leukemic cell lines and primary childhood leukemia samples using both real-time quantitative PCR (RQ-PCR) and flow cytometry. WT1 protein was highly expressed in the leukemic cell lines K562, HL-60, PLB 985, KG-1a and CEM. By contrast, 40 primary samples of acute lymphoblastic leukemia (ALL; B-ALL, n = 15 and T-ALL, n = 10) and acute myeloid leukemia (n = 15) expressed low levels of WT1 protein. RQ-PCR detected WT1 transcript levels in the same range as reported in earlier studies in childhood acute leukemia. The results of this study indicate the following: (i) there are considerable discrepancies between WT1 transcripts and protein expression; (ii) WT1 is not a suitable marker for flow cytometric MRD detection in childhood acute leukemia.

[One-step real-time fluorescence quantitative PCR for detecting WT1 mRNA expression in leukemia]

OBJECTIVE

To establish a one-step real-time quantitative RT-PCR assay for detecting the expression of WT1 mRNA, which allows detection of the minimal residue disease and prognostic prediction in leukemic patients.

METHODS

WT1 gene fragment was amplified from the RNAs extracted from K562 cells using one-step RT-PCR. The quantitative standard were constructed by pMD 18-T vector cloning, and a Taqman-MGB fluorescent probe and a pair of primers were used to establish the one-step real-time fluorescence quantitative RT-PCR assay for WT1 gene detection. The sensitivity, repeatability and stability of this assay were evaluated and verified.

RESULTS

The sensitivity of this assay reached the 10(-4) level. The standard template of 1.0 x 10(6)-1.0 x 10(2) copies/ml were amplified by the one-step real-time fluorescence quantitative RT-PCR assay , and the Ct value was strongly correlated (r=0.998) to the logarithm of the initial template concentration. The repetition Ct value and both the inter-tube and inter-batch coefficients of variation (CV%) were less than 8%.

CONCLUSION

The one-step real-time fluorescence quantitative RT-PCR assay has good sensitivity, repeatability and specificity, and the one-step completion of the reverse transcription and PCR processes may reduce the operational complexities and the possibility of contamination.

Fallopian tube malignant mixed müllerian tumor (carcinosarcoma): a case report with immunohistochemical profiling

We report a case of malignant mixed müllerian tumor (MMMT) (carcinosarcoma) of the right fallopian tube in a 69-year-old woman presenting with abdominal pain and an adnexal mass. The patient underwent total abdominal hysterectomy, bilateral salpingo-oophorectomy, omentectomy, received adjuvant chemotherapy and is without evidence of disease 12 months postoperatively. The tumor involved the fallopian tube and was composed of in situ and invasive high-grade serous and undifferentiated carcinoma, leiomyosarcoma, rhabdomyosarcoma and undifferentiated sarcoma. Immunohistochemically, the epithelial and mesenchymal cells expressed CD56, Leu-7 and p53. The epithelial elements expressed nuclear WT1 and calretinin while the mesenchymal cells showed negative nuclear and strong cytoplasmic staining. HBME was observed focally in carcinoma. The expression of mesothelial-associated antigens WT1, calretinin and HBME in MMMT likely reflects the common embryologic derivation of the mesothelium and urogenital ridge. Loss of nuclear WT1 expression in the mesenchymal component may be involved in MMMT tumorigenesis.

Biomarker-assisted diagnosis of ovarian, cervical and pulmonary small cell carcinomas: the role of TTF-1, WT-1 and HPV analysis

AIMS

Small cell carcinoma of the ovary, hypercalcaemic-type (SCCOH) is morphologically similar to small cell carcinomas from other sites. The aims of this study were to (i) determine if a biomarker panel would distinguish small cell carcinomas of the ovary, cervix (SCCCx) and lung (SCCLu) and (ii) potentially determine the histogenesis of SCCOH.

METHODS AND RESULTS

Nine ovarian small cell carcinomas (seven hypercalcaemic type; two pulmonary type), eight SCCCx and 22 SCCLu were immunostained for thyroid transcription factor (TTF)-1, WT-1, p16, cKIT and OCT3/4; a subset of cases were tested for human papillomavirus (HPV). WT-1 was diffusely positive in 6/7 SSCOH versus two of 33 other small cell carcinomas (P <or= 0.001). TTF-1 was diffusely positive in 20/22 SCCLu and 1/8 SCCCx, and negative in all SCCOH. p16 and cKIT demonstrated variable patterns of immunoreactivity in all cases. HPV was identified in 5/6 SCCCx; SCCOH and SCCLu were negative for HPV.

CONCLUSIONS

Combined staining with WT-1 and TTF-1 will distinguish SCCOH from SCCLu and SCCCx with a sensitivity of 86% and specificity of 97%. HPV is specific for tumours of cervical origin, but p16 immunohistochemistry is not useful for this purpose. The presence of diffuse WT-1 supports a Müllerian origin for SCCOH, whereas the absence of cKIT and OCT3/4 argues against a germ cell origin.

Diagnostic Utility of WT1 Immunostaining in Ovarian Sertoli Cell Tumor

WT1, the Wilms tumor gene product, can be expressed in various tumors from different anatomic sites, including some types of ovarian tumors. Regarding the latter, most studies have focused on surface epithelial-stromal tumors in which serous carcinomas are usually positive and endometrioid carcinomas are negative. Very few studies have specifically investigated this marker in ovarian sex cord-stromal tumors; however, limited data in the literature suggest that WT1 may be frequently expressed in sex cord-stromal tumors. As pure Sertoli cell tumor can be in the histologic differential diagnosis of endometrioid tumors (particularly borderline tumor and carcinoma) and carcinoid, immunostaining for WT1 might be of diagnostic value. Immunohistochemical staining for WT1 was performed in 108 ovarian tumors: pure Sertoli cell tumor (n=26), endometrioid borderline tumor (n=25), classic well-differentiated endometrioid carcinoma (n=23), sertoliform endometrioid carcinoma (n=12), and carcinoid (n=22). Additionally, inhibin and calretinin immunostaining were performed in all cases of Sertoli cell tumor for purposes of comparing expression with WT1. Extent of immunostaining was scored on a 0 to 4+ semiquantitative scale, and immunohistochemical composite scores based on a combination of extent and intensity of immunostaining were calculated in positive cases (possible range, 1 to 12). Nuclear expression of WT1 was present in 96% of Sertoli cell tumors, 16% of endometrioid borderline tumors, 13% of classic well-differentiated endometrioid carcinomas, 25% of sertoliform endometrioid carcinomas, and 0% of carcinoids. In Sertoli cell tumors, expression was diffuse (>50% of positive cells) in all positive cases. When positive in the non-Sertoli cell tumors, the extent of expression tended to be focal to patchy (50% or less positive cells). In Sertoli cell tumors, inhibin and calretinin were expressed in 96% and 54% of cases, respectively. The extent of expression of inhibin tended to be diffuse, similar to WT1; however, the extent of immunostaining for calretinin tended to be focal to patchy. The immunohistochemical composite scores for WT1, inhibin, and calretinin were 11.2, 7.6, and 4.8, respectively. Coordinate patterns for the extent of expression of WT1, inhibin, and calretinin in pure Sertoli cell tumor showed that all 3 markers were positive in 54% of cases; however, 42% were positive for WT1 and inhibin but negative for calretinin. In cases positive for both WT1 and inhibin, expression of both markers was diffuse in 84% of cases, but WT1 was diffuse while inhibin was focal to patchy in 16% of cases. We conclude that ovarian Sertoli cell tumor should be added to the growing list of WT1-positive tumors. This marker is useful for the distinction of Sertoli cell tumor from endometrioid tumors and carcinoid. The diagnostic utility of WT1 in Sertoli cell tumor is similar to inhibin but better than that of calretinin.

Clinicopathological significance of WT1 expression in ovarian cancer: a possible accelerator of tumor progression in serous adenocarcinoma

Recently, oncogenic potential of the WT1 gene has been proposed in some human solid tumors and leukemias. Although previous studies have shown the frequent expression of the WT1 protein in ovarian serous adenocarcinomas (OSAs), its clinicopathologic significance is still unclear. We immunohistochemically examined the expression status of WT1 in 119 OSAs and analyzed the correlation of the intensity of WT1 immunoreactivity with the level of WT1 mRNA expression by quantitative real-time polymerase chain reaction, clinicopathologic variables, expression of p53, Bcl-2, and Ki-67 labeling index (LI). Of 119 OSAs, nuclear WT1 immunoreactivity was positive in 99 (83%), of which 44 (44%) and 55 (56%) exhibited high and low WT1 immunoreactivities, respectively. The quantitative WT1 mRNA levels were significantly correlated with the intensity of WT1 immunoreactivity (P < 0.05). In comparison with WT1-negative OSAs, the WT1-positive OSAs showed a higher grade (P = 0.007), advanced stage (P = 0.018), and higher Ki-67 LI (P < 0.001). Additionally, high WT1 immunoreactivity was correlated with a higher grade (P = 0.003), Ki-67 LI (P = 0.012), Bcl-2 expression (P = 0.003), and poorer patient outcome (5-year survival, 36.5 vs 63.8%, P = 0.008 by log-rank test). The WT1 protein may be an accelerator of the progression of OSA.

WT1 transcript amount discriminates secondary or reactive eosinophilia from idiopathic hypereosinophilic syndrome or chronic eosinophilic leukemia

Idiopathic hypereosinophilic syndromes (HES) comprise a spectrum of indolent to aggressive diseases characterized by persistent hypereosinophilia. Hypereosinophilia can result from the presence of a defect in the hematopoietic stem cell giving rise to eosinophilia, it can be present in many myeloproliferative disorders or alternatively it may be a reactive form, secondary to many clinical conditions. The hybrid gene FIP1L1-PDGRFalpha was identified in a subset of patients presenting with HES or chronic eosinophilic leukemia (CEL). In spite of this, the majority of HES patients do not present detectable molecular lesions and for many of them the diagnosis is based on exclusion criteria and sometimes it remains doubt. In this study we explored the possibility to distinguish between HES/CEL and reactive hypereosinophilia based on WT1 transcript amount. For this purpose, 312 patients with hypereosinophilia were characterized at the molecular and cytogenetic level and analyzed for WT1 expression at diagnosis and during follow-up. This study clearly demonstrates that WT1 quantitative assessment allows to discriminate between HES/CEL and reactive eosinophilia and represents a useful tool for disease monitoring especially in the patients lacking a marker of clonality.

Immunohistochemical marker panels for distinguishing between epithelioid mesothelioma and lung adenocarcinoma

The distinction between epithelioid mesothelioma and lung adenocarcinoma remains an important diagnostic challenge for surgical pathologists. The aim of the present study was to select a limited and appropriate panel of antibodies that can differentiate between epithelioid mesothelioma and lung adenocarcinoma. Specimens of 90 epithelioid mesotheliomas and 51 lung adenocarcinomas obtained from Japanese cases were examined using calretinin, WT1, AE1/AE3, CAM5.2, cytokeratin (CK) 5/6, vimentin, epithelial membrane antigen (EMA), thrombomodulin, CEA, CA19-9, and CA125. Ninety-six percent of epithelioid mesotheliomas were positive for calretinin; 99% for WT1; 100% for AE1/AE; 97% for CAM5.2; 70% for CK 5/6; 91% for vimentin; 96% for EMA; 71% for thrombomodulin; 77% for mesothelin; 7% for CEA; 17% for CA19-9; and 85% for CA125. In contrast, 33% of lung adenocarcinomas were positive for calretinin; 16% for WT1; 100% for AE1/AE3, CAM5.2, and EMA; 41% for CK 5/6; 47% for vimentin; 20% for thrombomodulin; 69% for mesothelin; 98% for CEA; 73% for CA19-9; and 80% for CA125. For distinguishing between epithelioid mesothelioma and lung adenocarcinoma, the combination of CEA, calretinin and each WT1 or thrombomodulin was suggested to be the best panel of immunohistochemical markers.

A tumor suppressor and oncogene: the WT1 story

The Wilms' tumor 1 (WT1) gene encodes a transcription factor important for normal cellular development and cell survival. The initial discovery of WT1 as the causative gene in an autosomal-recessive condition identified it as a tumor suppressor gene whose mutations are associated with urogenital disease and the development of kidney tumors. However, this view is not in keeping with the frequent finding of wild-type, full-length WT1 in human leukemia, breast cancer and several other cancers including the majority of Wilms' tumors. Rather, these observations suggest that in those conditions, WT1 has an oncogenic role in tumor formation. In this review, we explore the literature supporting both views of WT1 in human cancer and in particular human leukemias. To understand the mechanism by which WT1 can do this, we will also examine its functional activity as a transcription factor and the influence of protein partners on its dual behavior.

Immunohistochemistry of primary malignant neuroepithelial tumors of the kidney: a potential source of confusion?

Ewing sarcoma/peripheral primitive neuroectodermal tumor (pPNET) is a rare primary tumor of the kidney with morphologic features similar to those of other primitive tumors. Previous studies have shown that these tumors frequently stain positively with immunostains against CD99 and FLI-1 and negatively with stains against WT-1, suggesting that these markers may be used for the distinction between Wilms tumor and pPNET. We present 30 cases of primary malignant neuroepithelial tumor with immunohistochemical profiles and reverse transcriptase polymerase chain reaction (RT-PCR) analysis and show that immunophenotypic overlap exists between Wilms tumor and pPNET. A subset of 30 neuroepithelial tumors from the National Wilms Tumor Study originally categorized as putative pPNETs of the kidney was stained with FLI-1, WT-1, and thyroid transcription factor-1. Bicolor fluorescence in situ hybridization studies were performed on 19 of the cases. Other data on these tumors were available from a previous study (Am J Surg Pathol 2001;25:133). Of 7 primary tumors that had the EWS/FLI-1 fusion transcript by RT-PCR, 6 exhibited strong immunopositivity for FLI-1. Nine that were negative by RT-PCR stained positively with the FLI-1 stain. Five fusion-negative cases stained with both FLI-1 and WT-1. Three fusion-negative cases were negative for FLI-1 but positive for WT-1. Five fusion-negative cases were negative for both FLI-1 and WT-1. Of the 30 cases, 29 were positive for CD99. Seven cases that were negative for the EWS-FLI-1 fusion by RT-PCR were positive by fluorescence in situ hybridization. All cases were negative for thyroid transcription factor-1. Reliance upon immunohistochemistry as the sole means of ancillary diagnosis in renal pPNET can lead to confusing results. We recommend molecular fusion studies for clarification of primitive renal tumors with unexpected immunophenotypic results.

Immunohistochemical detection of WT1 protein in a variety of cancer cells

WT1 was first identified as a tumor suppressor involved in the development of Wilms' tumor. Recently, oncogenic properties of WT1 have been demonstrated in various hematological malignancies and solid tumors. Because WT1 has been identified as a molecular target for cancer immunotherapy, immunohistochemical detection of WT1 in tumor cells has become an essential part of routine practice. In the present study, the expression of WT1 was examined in 494 cases of human cancers, including tumors of the gastrointestinal and pancreatobiliary system, urinary tract, male and female genital organs, breast, lung, brain, skin, soft tissues and bone by immunohistochemistry using polyclonal (C-19) and monoclonal (6F-H2) antibodies against WT1 protein. Staining for C-19 and 6F-H2 was found in 35-100 and 5-88% of the cases of each kind of tumor, respectively. WT1-positive tumors included tumor of the stomach, prostate, and biliary and urinary systems, and malignant melanomas. A majority of the positive cases showed diffuse or granular staining in the cytoplasm, whereas ovarian tumors and desmoplastic small round cell tumors frequently showed nuclear staining. Glioblastomas, some of soft tissue sarcomas, osteosarcomas, and malignant melanomas of the skin showed extremely strong cytoplasmic staining as compared with other tumors. Western blot analysis showed that WT1 protein was predominantly expressed in the cytoplasm of the tumor cells in two cases of lung adenocarcinoma, supporting the intracytoplasmic staining for WT1 using immunohistochemistry. Immunohistochemical detection with routinely processed histologic sections could provide meaningful information on the expression of WT1 in cancer cells.

Atypical development of Sertoli cells and impairment of spermatogenesis in the hypogonadal (hpg) mouse

Testes of hypogonadal (hpg) mice show arrested postnatal development due to congenital deficiencies of gonadotrophin-releasing hormone (GnRH) and gonadotrophin synthesis and secretion. Follicle-stimulating hormone (FSH), androgen or oestrogen treatment restore qualitatively normal spermatogenesis in hpg testes. Understanding the cellular and molecular changes accompanying hormone-induced spermatogenesis in hpg mice requires detailed morphological analyses of the germ cells and Sertoli cells in the untreated hpg testis. We compared seminiferous epithelial cytology in adult hpg, immature and adult wild-type mice using unbiased optical disector-based stereology, immunolocalization of Sertoli cell microtubules (MT), espin (a component of the blood-testis barrier), markers of Sertoli cell maturity (p27(kip1) and WT-1), and electron microscopy. Hpg testes had marked reductions in weight, seminiferous cord volume and length, and severe spermatogenic impairment with germ cells per testis < 1% of adult wild-type testes. Sertoli cell nuclei expressed WT-1 in hpg testes, but often were centrally located, similar to 9-14-day-old wild-type testes, and they expressed p27(kip1), indicating that hpg Sertoli cells were post-mitotic. Hpg testes had significantly (P < 0.05) reduced Sertoli cells per testis (0.56 million) compared with 10-day wild-type (1.15 million) and adult wild-type testes (2.06 million). Immunofluorescence labelling of normal adult Sertoli cells showed supranuclear MT columns and basally located espin, but these features were absent in 10-day-old and hpg Sertoli cells. Hpg Sertoli cells showed pleomorphic nuclear ultrastructure with mature-type nucleoli, similar to normal adult-type Sertoli cells, but hpg Sertoli cells exhibited incomplete tight junctions that lacked ectoplasmic specializations. We conclude that in hpg mice, chronic gonadotrophin insufficiency restrains Sertoli cell proliferation and maturation, forming pseudo-adult-type Sertoli cells that are incapable of supporting germ cell proliferation and maturation.

Evaluation of 12 antibodies for distinguishing epithelioid mesothelioma from adenocarcinoma: identification of a three-antibody immunohistochemical panel with maximal sensitivity and specificity

We evaluated the sensitivity and specificity of 10 monoclonal and two polyclonal antibodies for distinguishing epithelioid mesothelioma from adenocarcinoma (AdCA) using immunohistochemistry (IHC). The antibodies were directed against the mesothelial-associated antigens mesothelin, calretinin, cytokeratin 5, thrombomodulin, Wilms' tumor-1 (WT-1) gene product and HBME-1, and the nonmesothelial antigens Lewis-Y blood group (antibody BG8), MOC-31, BerEp4, CD15, and carcinoembryonic antigen (CEA) family. The 133 tumors evaluated included 65 malignant epithelioid mesotheliomas, 22 lung AdCAs, 27 ovarian serous carcinomas, 24 breast carcinomas, and five gastric carcinomas. Diagnoses were based on clinical, histologic, ultrastructural, and/or IHC findings. Calretinin had the best sensitivity for mesothelioma (95%), followed by HBME-1 (84%), WT-1 (78%), cytokeratin 5 (76%), mesothelin (75%), and vimentin and thrombomodulin (68%). Thrombomodulin had the best specificity for mesothelioma (92%), followed by cytokeratin 5 (89%), calretinin (87%) vimentin (84%), and HBME-1 (45%). When ovarian carcinomas were excluded from the analysis, the specificity of mesothelin and WT-1 for the diagnosis of mesothelioma increased to 90 and 81%, respectively. The sensitivity of the nonmesothelial antigens for AdCA was organ dependent, with BG8 performing best in the breast cancer group (96%), and BerEp4, BG8, MOC-31 performing best in the lung cancer group (100%). The specificity of the nonmesothelial antigens for AdCA was 98% for BG8 and CEA, 97% for CD15, 95% for BerEp4, and 87% for MOC-31. A novel statistical analysis technique employing logic regression analysis identified a three-antibody immunohistochemical panel including calretinin, BG8, and MOC-31, which provided over 96% sensitivity and specificity for distinguishing epithelioid mesothelioma from AdCA.

The diagnostic utility of immunohistochemistry in distinguishing between epithelioid mesotheliomas and squamous carcinomas of the lung: a comparative study

As both mesotheliomas and squamous carcinomas can present a wide variety of morphological patterns, they can on occasion be confused. Recently, some groups of investigators have called attention to the difficulties that sometimes exist in distinguishing between these malignancies and the need to define a panel of markers that can assist in reaching the correct diagnosis. The aim of the present study is to compare the value of the various immunohistochemical markers currently available for the diagnosis of mesothelioma and squamous carcinoma of the lung. A total of 30 epithelioid pleural mesotheliomas exhibiting a solid or predominantly solid pattern, and 30 nonkeratinizing squamous carcinomas of the lung were investigated for the expression of the following markers: podoplanin, calretinin, mesothelin, WT1, keratin 5/6, keratin 7, p63, carcinoembryonic antigen (CEA), MOC-31, Ber-EP4, B72.3, BG-8 (Lewis(y)), leu-M1 (CD15), and thyroid transcription factor-1 (TTF-1). All 30 (100%) of the mesotheliomas reacted for calretinin, mesothelin and keratin 7, 93% each for podoplanin, WT1 and keratin 5/6, 13% for Ber-EP4, 7% each for p63, MOC-31 and BG-8, and 0% for B72.3, CEA, leu-M1 and TTF-1. All 30 (100%) of the squamous carcinomas were positive for p63 and keratin 5/6, 97% for MOC-31, 87% for Ber-EP4, 80% for BG-8, 77% for CEA, 57% for keratin 7, 40% for calretinin and B72.3, 30% for leu-M1, 27% for mesothelin, 15% for podoplanin, and 0% for WT 1 and TTF-1. After analyzing the results, it is concluded that from a practical point-of-view, a combination of two positive mesothelioma markers (WT1 and calretinin or mesothelin) with two negative mesothelioma markers (p63 and MOC-31) would allow the differential diagnosis to be established between epithelioid mesotheliomas and squamous carcinomas of the lung in nearly all instances.

Presence of WT1 in nuclear messenger RNP particles in the human acute myeloid leukemia cell lines HL60 and K562

The WT1 gene is a key player in acute myeloid leukaemia, in which it is frequently over-expressed. WT1 encodes a multifunctional zinc finger protein transcription factor, which also binds mRNA. Thus increasing evidence suggests that WT1 works both at the DNA and mRNA level, not only in the urogenital system but also in other contexts. Nuclear poly(A)(+) mRNP particles were isolated by oligo(dT) chromatography from the human acute myeloid leukemia cell lines HL60 and K562, and analysed by Western blotting and 2D minigels. MALDI-TOF demonstrated the presence of hnRNP proteins, splice factors, and unexpectedly vimentin in the mRNP fraction. WT1 was also shown to be present in nuclear mRNP particles suggesting that in leukaemia, and by extension in all cancers in which it is involved, WT1 works both at the DNA and mRNA target level.

Alpha-methylacyl-CoA racemase as a marker in the differential diagnosis of metanephric adenoma

Metanephric adenoma (MA), a well-described renal neoplasm, usually behaves in a benign fashion. It may have areas that are morphologically similar to papillary renal cell carcinoma (RCC) type, or epithelial (tubular predominant) type Wilms' tumor. Prior immunohistochemical studies of MA have reported variable staining patterns. Alpha-methylacyl-CoA racemase (AMACR), a molecular marker for prostate carcinoma, has subsequently been found to be overexpressed in breast, colorectal and ovarian cancers, among others. Recent microarray analysis of renal tumors has shown an increase of AMACR mRNA levels in papillary RCC but not in other subtypes. We investigated the utility of immunohistochemical staining for AMACR, cytokeratin 7(CK7), CD57 and WT1 to differentiate between the above-mentioned three neoplasms. Immunohistochemical stains were performed on paraffin-embedded tissue sections from 25 papillary RCC, 10 MAs and eight Wilms' tumors. AMACR was positive in one (10%) of 10 MAs and 24 (96%) of 25 papillary RCC, while it was negative in all Wilms' tumors. CK7 was positive in 20 of 25 papillary RCCs, focally positive in one Wilms' tumor and was negative in all MAs. CD57 was positive in all six MAs that were stained, focally positive in one of 25 papillary RCC and one of eight Wilms' tumors. WT1 was positive in seven of 10 MAs, three of 25 papillary RCCs and all eight Wilms' tumors. In conclusion, diffuse and strong immunoreactivity for AMACR may be useful in differentiating papillary RCC from MA but a panel which includes AMACR, CK7 and CD57 is better in this differential diagnosis. AMACR is not helpful in differentiating MA from Wilms' tumor, but CD57 is helpful in this differential diagnosis. WT1 may be useful in separating Wilms' tumor from MA and papillary RCC but is not helpful in differentiating MA from papillary RCC.

The serosal mesothelium is a major source of smooth muscle cells of the gut vasculature

Most internal organs are situated in a coelomic cavity and are covered by a mesothelium. During heart development, epicardial cells (a mesothelium) move to and over the heart, undergo epithelial-mesenchymal transition (EMT), and subsequently differentiate into endothelial and vascular smooth muscle cells. This is thought to be a unique process in blood vessel formation. Still,structural and developmental similarities between the heart and gut led us to test the hypothesis that a conserved or related mechanism may regulate blood vessel development to the gut, which, similar to the heart, is housed in a coelomic cavity. By using a combination of molecular genetics, vital dye fate mapping, organ culture and immunohistochemistry, we demonstrate that the serosal mesothelium is the major source of vasculogenic cells in developing mouse gut. Our studies show that the gut is initially devoid of a mesothelium but that serosal mesothelial cells expressing the Wilm's tumor protein (Wt1)move to and over the gut. Subsequently, a subset of these cells undergoes EMT and migrates throughout the gut. Using Wt1-Cre genetic lineage marking of serosal cells and their progeny, we demonstrate that these cells differentiate to smooth muscle of all major blood vessels in the mesenteries and gut. Our data reveal a conserved mechanism in blood vessel formation to coelomic organs, and have major implications for our understanding of vertebrate organogenesis and vascular deficiencies of the gut.

HIV-1 Nef induces dedifferentiation of podocytes in vivo: a characteristic feature of HIVAN

OBJECTIVE

To determine the specific role of Nef in the pathogenesis of HIV-associated nephropathy.

DESIGN

Podocytes are highly differentiated non-dividing cells in the normal glomerulus, however, they undergo dedifferentiation and acquire a proliferative phenotype in HIVAN patients, in HIV-transgenic mice and if infected by HIV-1 in vitro. These changes are accompanied by loss of the maturation markers synaptopodin and WT1, and expression of the proliferation marker Ki-67. Previously, we mapped the gene responsible for these changes in vitro to HIV-1 Nef. To determine the role of Nef in vivo, we developed a transgenic mouse model in which Nef was exclusively expressed in podocytes.

METHODS

Transgenic mice were generated using a construct in which Nef expression was blocked by a floxed lacZ intervening gene. When crossed with another transgenic mice expressing Cre under the Podocin promoter (a podocyte specific gene), the intervening lacZ gene was removed activating the expression of Nef in podocytes. The in vivo expression profiles of the Nef, the proliferation marker Ki-67, the differentiation markers synaptopodin and WT1, and phospho-Stat3, were determined by immunohistochemistry.

RESULTS

Podocyte-specific expression of Nef induced loss of synaptopodin and WT1, and expression of Ki-67 in podocytes. Furthermore, Nef activated expression of phospho-Stat3, one of the downstream signaling pathways for cell proliferation.

CONCLUSIONS

We conclude that Nef induces the early molecular changes in podocytes that are essential for the dedifferentiation and proliferation of podocytes in HIVAN pathogenesis. These data provide the first clear molecular evidence that Nef alters the podocyte phenotype in vivo.

Differential expression of WT-1 in serous carcinomas in the peritoneum with or without associated serous carcinoma in endometrial polyps

Although differential WT-1 expression between ovarian and uterine serous carcinoma has been discussed in the literature, there have been no studies of WT-1 expression in serous carcinomas in the peritoneum with or without concurrent serous carcinoma in an endometrial polyp. This study addresses this issue and includes a small series of uterine and ovarian serous carcinomas for comparison. Nine peritoneal serous carcinomas with coexistent serous carcinoma in an endometrial polyp, 10 peritoneal serous carcinomas without serous carcinoma in an endometrial polyp, 9 uterine serous carcinomas, and 12 ovarian serous carcinomas were stained with antibody to WT-1. Ninety-two percent of ovarian serous carcinomas and 80% of peritoneal serous carcinomas without serous carcinoma involving an endometrial polyp expressed WT-1. In contrast, 12% of peritoneal serous carcinomas with serous carcinoma in an endometrial polyp expressed WT-1 with the serous carcinoma in the endometrial polyp staining concordantly. For uterine serous carcinoma without an endometrial polyp, only 11% expressed WT-1. Peritoneal serous carcinomas without coexistent serous carcinoma in an endometrial polyp have a WT-1 expression pattern similar to ovarian serous carcinoma while peritoneal serous carcinomas with coexistent serous carcinoma in an endometrial polyp have a staining pattern similar to uterine serous carcinoma. The difference in WT-1 expression among serous carcinomas suggests a difference in biology based on the site of origin. Additionally, the difference in WT-1 expression between peritoneal serous carcinomas with and without coexistent serous carcinoma in endometrial polyps suggests that peritoneal serous carcinoma may have different pathogenetic pathways.

An immunohistochemical comparison between low-grade and high-grade ovarian serous carcinomas: significantly higher expression of p53, MIB1, BCL2, HER-2/neu, and C-KIT in high-grade neoplasms

Ovarian serous carcinoma (OSC) is the most common ovarian epithelial malignancy. Recently, a dualistic pathway of ovarian serous carcinogenesis has been proposed based on morphologic observations and molecular genetic analysis. In this scheme, low-grade OSC arises in a stepwise fashion from a benign serous cystadenoma through a usual serous borderline tumor through a micropapillary variant of serous borderline tumor. In contrast, the more common high-grade OSC arises de novo from the ovarian surface epithelium or the epithelium of cortical inclusion cysts with an as yet unrecognized precursor lesion. Although the division of OSC into low- and high-grade variants is gaining greater acceptance, and although there is accumulating molecular genetic evidence for this, there is little published information regarding a comparison of protein expression between these two types of OSC. In this study, we have investigated the immunohistochemical expression of a wide range of proteins in cases of low-grade (n = 22) and high-grade (n = 47) OSC. Antibodies used were p53, MIB1, BCL2, WT1, HER-2/neu, C-KIT, osteopontin, and survivin. For all antibodies, except MIB1, cases were scored as 0 (negative or occasional positive cells), 1+ (<10% cells positive), 2+ (10%-25% cells positive), 3+ (26%-50% cells positive), 4+ (51%-75% cells positive) or 5+ (>75% cells positive). For MIB1, the percentage of positive nuclei was calculated. There was a statistically significant higher expression of p53, MIB1, BCL2, HER-2/neu, and C-KIT in high-grade compared with low-grade OSC (P < 0.05). Thirty of 47 (64%) cases of high-grade OSC exhibited 5+ staining with p53 compared with 4 of 22 (18%) low-grade neoplasms. Twelve of 47 (26%) high-grade OSCs exhibited 5+ staining with BCL2 compared with 1 of 22 (5%) low-grade OSCs. The mean MIB1 proliferative index in high-grade OSCs was 55.4% compared with 23.0% in low-grade OSCs. Virtually all cases of both low-grade and high-grade OSCs exhibited diffuse nuclear positivity with WT1 and diffuse cytoplasmic positivity with survivin. Osteopontin expression was variable with no significant difference in expression between low-grade and high-grade OSC. Although expression of both HER-2/neu and C-KIT was significantly higher in high-grade compared with low-grade OSC, only rare cases exhibited strong positivity with these antibodies, which could be of therapeutic value in individual cases, although this would require additional molecular investigations. The significant differences in protein expression between low-grade and high-grade OSC provides further support for a different underlying pathogenesis. In particular, the differences in p53 immunoreactivity are in keeping with the observation that p53 gene mutation is more common in high-grade than low-grade OSC.

Changes in expression of WT1 isoforms during induced differentiation of the NB4 cell line

The levels of expression of WT1 gene and WT1+17AA isoforms rapidly decreased during the differentiation of NB4 cells induced by all-trans retinoic acid; this decrease was conversely related to the dynamic changes of CD11b positive cells, indicating that the abnormally high expression of WT1 gene and WT1+17AA isoforms was associated with a block of NB4 cell differentiation.

Monitoring minimal residual disease in BCR-ABL-positive chronic myeloid leukemia in the imatinib era

PURPOSE OF REVIEW

The total number of leukemia cells in the body is reduced very substantially in patients with BCR-ABL-positive chronic myeloid leukemia (CML) responding to imatinib. This reduction is seen first as restoration of Ph negativity in blood and marrow and thereafter as decreasing BCR-ABL transcript levels assayed by quantitative polymerase chain reaction (PCR). Most patients with newly diagnosed chronic-phase CML who receive imatinib achieve complete cytogenetic remission (CCYR) and low levels of BCR-ABL transcripts, a status that seems to predict for relatively long survival compared with previous treatments.

RECENT FINDINGS

Patients treated with 400 mg daily who achieved a reduction in BCR-ABL transcript numbers equal or greater than 3 logs compared with a baseline value have a significantly better progression-free survival than those who achieved lesser degrees of response. The presence of Ph-positive subclones with point mutations in the ABL kinase domain correlates with "acquired" resistance to imatinib and some mutations are associated with greater resistance than others. Preliminary evidence suggests that P-loop mutations are especially likely to be associated with progression to advanced-phase disease.

SUMMARY

Patients with CML should be monitored routinely by serial cytogenetic analysis of bone marrow until Ph negativity is achieved. Thereafter serial quantitative-PCR studies should be undertaken at approximately 3-month intervals and probably also bone marrow cytogenetic studies at longer intervals. Routine studies for ABL kinase domain mutations may also be advisable. The observation of increasing quantities of residual leukemia or expansion of a mutated clone suggests the need to modify therapy.

Wilms tumor gene product: sensitive and contextually specific marker of serous carcinomas of ovarian surface epithelial origin

Carcinomas of ovarian surface epithelial origin can arise from, and often present at, extraovarian sites. There are few available markers for the positive identification of carcinomas of ovarian surface epithelial origin, which might aid in distinguishing them from metastatic carcinomas, such as of breast, colon, or lung origin. Recently, the Wilms tumor gene product (WT-1) has been shown to be expressed in ovarian surface and mesothelial epithelium. We tested the hypothesis that WT-1 would be a sensitive and specific marker of ovarian surface epithelium carcinomas. An archived series of 116 ovarian carcinomas (57 serous [43 ovarian, 14 extraovarian], 31 mucinous, 15 clear cell, 13 endometrioid), 118 breast carcinomas, 46 colonic carcinomas, and 45 nonsmall cell lung cancers were selected. A polyclonal antibody to the WT-1 gene product was applied to deparaffinized, formalin-fixed tissue sections after epitope retrieval. Fifty-two of 57 (93%) serous carcinomas of ovarian surface epithelial origin were WT-1-positive, in a nuclear pattern, with virtually all the tumor cell population positive in the majority of cases. None of the mucinous, clear cell, or endometrioid ovarian cancers were positive, and only 8 of 118 breast, 0 of 46 colonic, and 0 of 45 lung nonsmall cell carcinomas were WT-1-positive. These findings demonstrate that WT-1 is a highly sensitive and specific marker of serous carcinomas of ovarian surface epithelial origin (both ovarian and extraovarian). These results also contradict recent reports demonstrating WT-1 expression in both breast and lung carcinomas.

WT1 as a universal marker for minimal residual disease detection and quantification in myeloid leukemias and in myelodysplastic syndrome

Monitoring of acute leukemia patients during and after treatment for the presence of remaining leukemic cells (minimal residual disease, MRD) has been shown to give major insight into the effectiveness of treatment. However, so far the applicability of this strategy has been limited to those leukemia subsets characterized by genetic markers amenable to sensitive detection by PCR. Although PCR for immunoglobulin and T cell receptor gene rearrangement represents the gold standard for MRD detection in most cases of ALL without any fusion gene transcripts as molecular markers available, the situation in AML is more complicated because, at present, more than 50% of them lack any sort of clonality markers suitable for MRD monitoring. Thus, a number of studies have been performed in an attempt to identify cytogenetic and molecular abnormalities associated with leukemic transformation. In this paper we describe the effectiveness of the quantitative assessment of the Wilms tumor gene (WT1) transcript as a molecular marker for the detection of the leukemic clone useful for monitoring the presence of MRD in all the patients affected by acute and chronic leukemias as well as myelodysplastic syndromes.

Desmoplastic Small Cell Tumor in the Pancreas

Desmoplastic small cell tumor (DSCT) is a distinct type of small blue cell tumors and is characterized by the unique karyotypic aberration involving the fusion of the Ewing's sarcoma (EWS) gene and Wilms' tumor (WT1) gene. Typically, it grows along serosal surfaces; however, in some cases, the tumor presents as a dominant mass in an internal organ. Examples of DSCT forming a primary mass in ovary, testes, and brain have been described, but its presentation as a primary pancreatic mass has not been reported previously. The case reported here is a 31-year-old woman who presented with a 14-cm mass in the pancreas. There were smaller nodules on the peritoneal surfaces that were regarded clinically as metastasis from a primary pancreatic tumor. During the frozen section, the diagnosis of a poorly differentiated endocrine carcinoma of pancreatic origin was rendered and patient underwent subtotal pancreatectomy. On microscopic examination, the tumor was composed of large nests and broad bands of small blue cells, separated by fibrous stroma. Immunohistochemical stains showed positivity of the tumor cells for cytokeratins (AE1:AE3 and CAM5.2), neuron specific enolase, desmin and WT1, whereas chromogranin, S-100, and CD99 were negative. Since this immunoprofile is characteristic of DSCT, molecular analysis was performed which revealed the presence of EWS-WT1 gene fusion characteristic of DSCT. This case shows that in addition to primary pancreatic tumors characterized by prominent cellularity such as solid pseudopapillary tumors, acinar cell carcinoma, pancreatoblastoma, endocrine tumors, and other small blue cell tumors, the differential diagnosis of cellular, stroma-poor neoplasia in the pancreas also includes DSCT. This case is also another demonstrative example of how DSCT may form a dominant mass in intraabdominal organs.

[Development of a new inspection diagnostic method: genetic screening of cancer]

Wilms' tumor gene WT1 mRNA is a new marker of leukemic blast cells for AML, ALL, and CML. The minimal residual disease(MRD) of leukemia can be detected at frequencies as low as 1 in 10(3) to 10(4) normal bone marrow cells and 1 in 10(5) normal peripheral blood mononuclear cells by means of the quantitation of WT1 mRNA (WT1 assay) using reverse transcriptase-polymerase chain reaction. Thus, the WT1 assay makes it possible to rapidly assess the effectiveness of treatment and to evaluate the degree of eradication of leukemic cells in individual leukemia patients. Furthermore, the WT1 assay can continuously assess the disease progression of myelodysplastic syndrome(MDS) and predict the evolution of MDS to overt AML within 6 months. Moreover, WT1 protein is highly immunogenic, thus, WT1 peptide-based cancer immunotherapy is effective.

[A novel mutation of NPHS2 identified in a Chinese family with steroid-resistant nephrotic syndrome]

OBJECTIVE

Autosomal recessive steroid-resistant nephrotic syndrome (SRNS) is a subgroup of familial nephrotic syndrome. A causative gene has been identified, that is NPHS2, in chromosome 1q25-31, which encodes podocin. This study aimed to detect NPHS2 mutation in a Chinese family with SRNS.

METHODS

Renal biopsy was performed on the proband and her sibling for routine histologic and immunohistochemical investigation and electron microscopic examination. The expressions of podocin, nephrin, alpha-actinin and WT1 in glomeruli of the proband were detected by indirect immunofluorescence. Peripheral blood samples were collected for genetic analysis from the proband and her parents, and 53 adults with normal urinalysis. Genomic DNA was isolated from peripheral blood leucocytes. Eight exons of NPHS2 were amplified by polymerase chain reaction. Mutational analysis was performed using denaturing high-performance liquid chromatography (DHPLC) and DNA fragments with aberrant elution profiles of both strands revealed by DHPLC were re-amplified and sequenced directly.

RESULTS

The histologic findings on kidney biopsies were focal segmental glomerulosclerosis. In controls, the distribution of staining with P35, rabbit against a human podocin recombinant protein (amino acids 135 - 383 = all the C-terminal part of the protein downstream the transmembrane domain), and P21, rabbit against a human podocin recombinant protein (amino acids 15 - 89 = all the N-terminal part of the protein upstream the transmembrane domain) showed a linear pattern along glomerular capillary walls on glomeruli, and the fluorescent intensity of the staining with P35 was intensely positive. The fluorescent intensity of the staining with P21 was positive. In the proband, the distribution of the staining with P35 showed uneven and nonlinear, and the fluorescent intensity of the staining with P35 was weakly positive. The staining with P21 was negative. The area, location, distribution and fluorescent intensity of the staining with nephrin, alpha-actinin and WT1 on glomeruli of the proband were the same as those in the controls. The DHPLC elution profiles of exon 4 of NPHS2 from the proband and her parent were aberrant. The chromatograms by sequencing detected in the exon 4 of NPHS2 showed a composite heterozygous mutation of both 467_468insT and 503G > A in the proband, a heterozygous mutation of 503G > A in her father, and a heterozygous mutation of 467_468insT in her mother, respectively.

CONCLUSION

The study demonstrated for the first time a novel mutation, 503G > A, of NPHS2 in Chinese kindred with autosomal recessive SRNS. A significantly decreased or negative expression was also revealed in glomeruli of the proband stained with two kinds of anti-podocin antibodies.