Expression of PAX2 in papillary serous carcinoma of the ovary: immunohistochemical evidence of fallopian tube or secondary Müllerian system origin?

PAX-2 is a helpful marker for diagnosing metastatic renal cell carcinoma: comparison with the renal cell carcinoma marker antigen and kidney-specific cadherin

CONTEXT

The diagnosis of metastatic renal cell carcinoma (RCC) remains problematic.

OBJECTIVE

To evaluate the role of PAX-2, a renal tubular cell transcription factor, in the diagnosis of metastatic RCC. PAX-2 expression in metastatic RCC was compared with that of the renal cell carcinoma marker antigen (RCCM) and kidney-specific cadherin (KSC), which are 2 known markers for RCC.

DESIGN

Immunostaining for PAX-2, RCCM, and KSC was performed on consecutive tissue sections of 95 metastatic RCCs (77 clear cell, 8 papillary, 5 sarcomatoid, and 5 collecting duct) and 183 metastatic tumors other than RCC.

RESULTS

For PAX-2, positive immunoreactivity was detected in 77% clear cell, 75% papillary, 100% collecting duct, and 0% sarcomatoid metastatic RCCs. For RCCM, positive immunoreactivity was detected in 49% clear cell, 75% papillary, 0% collecting duct, and 0% sarcomatoid metastatic RCCs. For KSC, only 2 metastatic clear cell RCCs (3%) were positive. In combination, all markers were positive in 0% of cases; all markers were negative in 23% of cases (17 clear cell, 1 papillary, and for all 5 sarcomatoid); and at least 1 marker was positive in 76% of cases (PAX-2 only in 28% of cases [21 clear cell, 1 papillary, and 5 collecting duct] and RCCM only in 3% of cases [2 clear, 1 papillary]). Of 183 metastatic tumors other than RCC, 14 were positive for PAX-2 (nodal metastasis of carcinoma of colon [1], breast [1], endometrium [1], and ovary [1]; and omental metastasis of carcinoma of uterus or ovary [10]).

CONCLUSIONS

PAX-2 is a sensitive and specific marker for metastatic RCC. The diagnostic yield would be marginally increased by adding RCCM, but not KSC, as an immunomarker.

Joint loss of PAX2 and PTEN expression in endometrial precancers and cancer

Latent endometrial carcinoma precancers are normal-appearing endometrial glands with sporadic loss of tumor suppressor gene function such as PTEN. Progression to carcinoma is inefficient and requires additional genetic damage that creates a histologic precursor lesion called endometrial intraepithelial neoplasia (EIN). In this study, we examined loss of PAX2 expression, a gene required for embryonic uterine development, during endometrial carcinogenesis. Normal proliferative, EIN, and malignant (endometrial adenocarcinoma) endometrial tissues were immunostained for PTEN and PAX2. Proliferative samples with loss of protein in at least one gland were scored as latent precancers. EIN and cancer lesions were scored by the majority pattern. Overall prevalence and topography of joint PAX2-PTEN expression loss was examined. The prevalence of PAX2 protein loss in the sequence of normal to precancer to cancer was 36%, 71%, and 77%, respectively, and for PTEN, it was 49%, 44%, and 68%, respectively. The normal endometrial prevalence of PAX2- or PTEN-deficient latent precancers was unaffected by biopsy indication, but increased significantly with age. Coincident loss of PAX2 and PTEN expression in an individual normal endometrium was seen in 21% of patients, but usually involved different glands. Coincident loss was more common in precancers (31%) and carcinoma (55%), in which case, both markers were protein null in an overlapping clonal distribution. PAX2 and PTEN protein loss occurs independently and accumulates with increasing age in latent precancers of normal premenopausal endometrium. Loss of function of both genes in an overlapping distribution characterizes the clinical emergence of a premalignant lesion which is carried forward to carcinoma.

PAX2 distinguishes benign mesonephric and mullerian glandular lesions of the cervix from endocervical adenocarcinoma, including minimal deviation adenocarcinoma

Mesonephric remnants of the cervix are vestiges of the embryonic mesonephric system which typically regresses during female development. Uncommonly, hyperplasia of the mesonephric remnants may occur. The differential diagnosis of exuberant mesonephric hyperplasia includes minimal deviation adenocarcinoma of the cervix, a tumor with deceptively bland morphology for which no reliable diagnostic biomarkers currently exist. PAX2 encodes a transcription factor necessary in the development of the Wolffian duct system, and the protein is expressed in several tumors of mesonephric origin, including renal cell carcinoma, Wilm tumor, and nephrogenic adenoma. We hypothesized that PAX2 may also be expressed in mesonephric lesions of the cervix and may distinguish mesonephric hyperplasia from minimal deviation adenocarcinoma of the cervix. We demonstrated that PAX2 was strongly and diffusely expressed in mesonephric remnants (6 of 6) and in mesonephric hyperplasia (18 of 18); however, no expression was noted in mesonephric adenocarcinoma (0 of 1). PAX2 was expressed in normal endocervical glands (including tunnel clusters and Nabothian cysts) (86 of 86), lobular endocervical glandular hyperplasia (5 of 5), tubal/tuboendometrioid metaplasia (8 of 8), and cervical endometriosis (13 of 14). In contrast, only 2 cases of endocervical adenocarcinoma were positive for PAX2 [invasive adenocarcinoma of the minimal deviation type (0 of 5), usual type (1 of 22), and endometrioid type (1 of 1)]. Adjacent adenocarcinoma in situ, as well as cases of pure adenocarcinoma in situ (0 of 6), were also PAX2 negative. PAX2 expression in the 2 positive endocervical adenocarcinomas was patchy and weak. Most (11 of 15) stage II endometrial endometrioid adenocarcinomas lacked PAX2 expression but 1 of 10 grade 1 tumors and 3 of 5 grade 2 tumors did express PAX2. These results suggest that PAX2 immunoreactivity may be useful to (1) distinguish mesonephric hyperplasia from minimal deviation adenocarcinoma, (2) to distinguish lobular endocervical glandular hyperplasia from minimal deviation adenocarcinoma, and (3) to distinguish endocervical tubal metaplasia or cervical endometriosis from endocervical adenocarcinoma in situ. Overall, a strong, diffuse nuclear PAX2 expression pattern in a cervical glandular proliferation predicts a benign diagnosis (positive predictive value 90%, negative predictive value 98%; P<0.001); however, PAX2 should not be interpreted in isolation from the architectural and cytologic features of the lesion as it may be expressed in some stage II endometrial adenocarcinomas involving the cervix.

MicroRNA profiling of BRCA1/2 mutation-carrying and non-mutation-carrying high-grade serous carcinomas of ovary

BACKGROUND

MicroRNAs (miRNA) are 20 approximately 25 nucleotide non-coding RNAs that inhibit the translation of targeted mRNA, and they have been implicated in the development of human malignancies. High grade serous ovarian carcinomas, the most common and lethal subtype of ovarian cancer, can occur sporadically or in the setting of BRCA1/2 syndromes. Little is known regarding the miRNA expression profiles of high grade serous carcinoma in relation to BRCA1/2 status, and compared to normal tubal epithelium, the putative tissue of origin for high grade serous carcinomas.

METHODOLOGY/PRINCIPAL FINDINGS

Global miRNA expression profiling was performed on a series of 33 high grade serous carcinomas, characterized with respect to BRCA1/2 status (mutation, epigenetic silencing with loss of expression or normal), and with clinical follow-up, together with 2 low grade serous carcinomas, 2 serous borderline tumors, and 3 normal fallopian tube samples, using miRNA microarrays (328 human miRNA). Unsupervised hierarchical clustering based on miRNA expression profiles showed no clear separation between the groups of carcinomas with different BRCA1/2 status. There were relatively few miRNAs that were differentially expressed between the genotypic subgroups. Comparison of 33 high grade serous carcinomas to 3 normal fallopian tube samples identified several dysregulated miRNAs (false discovery rate <5%), including miR-422b and miR-34c. Quantitative RT-PCR analysis performed on selected miRNAs confirmed the pattern of differential expression shown by microarray analysis. Prognostically, lower level miR-422b and miR-34c in high grade serous carcinomas were both associated with decreased disease-specific survival by Kaplan-Meier analysis (p<0.05).

CONCLUSIONS/SIGNIFICANCE

High grade serous ovarian carcinomas with and without BRCA1/2 abnormalities demonstrate very similar miRNA expression profiles. High grade serous carcinomas as a group exhibit significant miRNA dysregulation in comparison to tubal epithelium and the levels of miR-34c and miR-422b appear to be prognostically important.

PAX2 expression in low malignant potential ovarian tumors and low-grade ovarian serous carcinomas

Ovarian tumors of low malignant potential and low-grade ovarian serous carcinomas are thought to represent different stages on a tumorigenic continuum and to develop along pathways distinct from high-grade ovarian serous carcinoma. We performed gene expression profiling on three normal human ovarian surface epithelia samples, and 10 low-grade and 10 high-grade ovarian serous carcinomas. Analysis of gene expression profiles of these samples has identified 80 genes upregulated and 232 genes downregulated in low-grade ovarian serous carcinomas. PAX2 was found to be one of the most upregulated genes in low-grade ovarian serous carcinoma. The upregulation of PAX2 was validated by real-time quantitative RT-PCR, western blot and immunohistochemical analyses. Real-time RT-PCR showed a statistically significant difference in PAX2 mRNA expression (expressed as fold change in comparison to normal human ovarian surface epithelia) among ovarian tumors of low malignant potential (1837.38, N=8), low-grade (183.12, N=17), and high-grade (3.72, N=23) carcinoma samples (P=0.015). Western blot analysis revealed strong PAX2 expression in ovarian tumors of low malignant potential (67%, N=3) and low-grade carcinoma samples (50%, N=10) but no PAX2 protein expression in high-grade carcinomas (0%, N=10). Using immunohistochemistry, tumors of low malignant potential (59%, N=17) and low-grade carcinoma (63%, N=16) samples expressed significantly stronger nuclear staining than high-grade ovarian carcinoma samples (9.1%, N=263). Furthermore, consistent with earlier immunohistochemical findings, PAX2 expression was expressed in the epithelial cells of fallopian tubes but not in normal ovarian surface epithelial cells. Our findings further support the two-tiered hypothesis that tumors of low malignant potential and low-grade ovarian serous carcinoma are on a continuum and are distinct from high-grade ovarian carcinomas. In addition, the absence of PAX2 expression in normal ovarian epithelia but expression in fallopian tube fimbria and ciliated epithelial inclusions would suggest the potential development of tumors of low malignant potential and of low-grade ovarian serous carcinomas from secondary Müllerian structures.

Identification of an immunogenic HLA-A*0201-binding T-cell epitope of the transcription factor PAX2

PAX2 is a transcription factor and member of the highly conserved family of paired box genes. PAX2 is aberrantly expressed in a variety of solid and hematologic malignancies. PAX2 regulates the transcription factor Wilms tumor gene 1, which is a promising target of cancer immunotherapy. The aim of this study was to apply a modified reverse immunology strategy to identify immunogenic epitopes of PAX2 which could be useful for cancer immunotherapy. Thirteen potential HLA-A*0201 epitopes were predicted by a major histocompatibility complex binding algorithm (SYFPEITHI) and a proteasome cleavage algorithm (PAProC) and screened for recognition by T cells from HLA-A*02-positive cancer patients using intracellular cytokine cytometry. Epitope-specific T cells were generated from CD4CD25 regulatory T-cell-depleted peripheral blood mononuclear cell. Nine of 20 colorectal cancer patients, 1 of 13 renal cell carcinoma patients, and 2 of 17 lymphoma patients had a spontaneous CD8 T-cell response toward at least 1 of 6 PAX2 peptide pools. None of the 20 healthy subjects showed reactivity toward PAX2. PAX2.337-345 (TLPGYPPHV)-specific T cells could repeatedly be generated, which specifically lysed the PAX2 expressing colorectal tumor cell line SW480. In this study, a modified reverse immunology strategy was employed to identify a first immunogenic HLA-A*0201 restricted T-cell epitope and natural ligand of the tumor antigen PAX2. Thus, PAX2 is another embryonic transcription factor, which is of potential interest as immunotherapy target antigen.

Pattern of retroperitoneal dissemination of primary peritoneum cancer: basis for rational use of lymphadenectomy

INTRODUCTION

The rationale for lymphadenectomy in primary peritoneal cancer (PPC) is unclear. We sought to define the pattern of lymphatic metastasis in PPC and propose evidence-based rationale for lymphadenectomy in relevant cases.

METHODS

Patients with PPC undergoing primary surgery at Mayo Clinic were identified. Demographics, tumor characteristics, procedures performed and follow up were analyzed.

RESULTS

Forty eight patients with PPC were identified; 39 had stage IIIC (81.2%) and 9 (18.8%) had stage IV. Residual disease (RD) after primary surgery was microscopic in 6 cases (12.5%), less than 1 cm in 33 (68.8%), more than 1 cm in 9 patient (18.7%) with median survivals of 5.8, 3.2 and 1.3 years, respectively. Overall, 24 patients had lymphadenectomy performed (pelvic (PND) or paraortic (PAND) or both). Pelvic nodes were involved in 12/23 (52.7%) cases, while para-aortic nodes were involved in 5/21 (23.8%) of cases. The rate of simultaneously positive pelvic and para-aortic nodes was 20% (4/20). Nodal involvement was a poor prognostic factor with 5 year overall survival 63% vs. 25% (p=0.014) in node positive vs. negative cases. Compared to patients with primary ovarian cancer (OC), OC cases had a higher rate of positive para-aortic nodes (57.6%: 77/132; p=0.004).

CONCLUSIONS

Retroperitoneal lymph nodes are a common site of metastases in PPC, therefore it is logically consistent to perform PND and PAND if a patient can be cytoreduced to microscopic RD in other sites or remove grossly positive nodes in patients with RD<1 cm.

PAX-2 in the diagnosis of primary renal tumors: immunohistochemical comparison with renal cell carcinoma marker antigen and kidney-specific cadherin

The diagnosis of renal cell carcinoma (RCC) remains problematic, especially in the context of metastasis or small needle biopsy specimens. The renal cell carcinoma marker (RCCM) and kidney-specific cadherin (KSC) are considered specific markers for RCC but are expressed preferentially in specific subtypes of RCC of lower grades. This study was aimed at evaluating the usefulness of PAX-2 in the diagnosis of renal tumors and comparing it with that of RCCM and KSC. Immunostaining for PAX-2, RCCM, and KSC was performed on consecutive tissue sections of 130 renal tumors. PAX-2 was successfully detected in routine tissue specimens. Although PAX-2 seems to be more sensitive than RCCM and KSC, there is significant staining overlap in relation to histologic subtypes, justifying the use of all 3 markers, which helps detect the vast majority of renal neoplasms. PAX-2 seems to have a significant role in renal neogenesis and may represent a novel therapeutic target.

Serous tubal intraepithelial carcinoma: its potential role in primary peritoneal serous carcinoma and serous cancer prevention

PURPOSE

A diagnosis of primary peritoneal serous carcinoma (PPSC) requires exclusion of a source in other reproductive organs. Serous tubal intraepithelial carcinoma (STIC; stage 0) has been described in asymptomatic women with BRCA mutations and linked to a serous cancer precursor in the fimbria. This study examined the frequency of STIC in PPSC and its clinical outcome in BRCA-positive women.

PATIENTS AND METHODS

Presence or absence of STIC was recorded in consecutive cases meeting the 2001 WHO criteria for PPSC, including 26 patients with nonuniform sampling of the fallopian tubes (group 1) and 19 patients with complete tubal examination (group 2; sectioning and extensively examining the fimbriated end, or SEE-FIM protocol). In selected cases, STIC or its putative precursor and the peritoneal tumor were analyzed for p53 mutations (exons 1 to 11). Outcome of STIC was ascertained by literature review.

RESULT

Thirteen (50%) of 26 PPSCs in group 1 involved the endosalpinx, with nine STICs (35%). Fifteen (79%) of 19 cases in group 2 contained endosalpingeal involvement, with nine STICs (47%). STIC was typically fimbrial and unifocal, with variable invasion of the tubal wall. In five of five cases, the peritoneal and tubal lesion shared an identical p53 mutation. Of 10 reported STICs in BRCA-positive women, all patients were without disease on follow-up.

CONCLUSION

The fimbria is the source of nearly one half of PPSCs, suggesting serous malignancy originates in the tubal mucosa but grows preferentially at a remote peritoneal site. The generally low risk of recurrence in stage 0 (STIC) disease further underscores STIC as a possible target for early serous cancer detection and prevention.

Expression of PAX8 in nephrogenic adenoma and clear cell adenocarcinoma of the lower urinary tract: evidence of related histogenesis?

Recent evidence has showed that nephrogenic adenoma is a true "nephrogenic" lesion derived from the proliferation of exfoliated and implanted renal tubular cells in the urinary tract, a process that closely resembles the formation of endometriosis. This new concept has led to the identification of renal transcription factor PAX2 as a diagnostic marker for nephrogenic adenoma. PAX8 is another transcription factor structurally and functionally related to PAX2. Both are cell lineage restricted transcription factors expressed in normal and neoplastic tissues of related origin, including renal tubular cells in both fetal and adult kidneys. In this study, we investigated the expression of PAX8 in nephrogenic adenoma and its mimics. We report here that PAX8 was detected in all nephrogenic adenomas (N=35) and clear cell adenocarcinoma of the lower urinary tract (N=7), but not in prostate adenocarcinoma (N=100), adenocarcinoma (N=9), squamous cell carcinoma (N=5), or urothelial carcinoma (N=48) of the urinary bladder and its variants. PAX8 was neither detected in normal urothelium of the urinary bladder nor in prostate glands and stroma. PAX2 was also detected in 2 of the 7 clear cell adenocarcinomas of the lower urinary tract. We suggest that PAX8 is an additional marker for identifying nephrogenic adenoma. Expression of PAX8 or PAX2 in both nephrogenic adenoma and clear cell adenocarcinoma of the lower urinary tract may indicate a possible related tissue origin for these 2 lesions; both may be derived from proliferating renal tubular cells in the urinary tract. In addition, detection of PAX8 or PAX2 in clear cell adenocarcinoma of the lower urinary tract is helpful in differentiating it from urothelial carcinoma and its variants and adenocarcinomas of the urinary bladder or of the prostate.

The utility of Pax-2 as an immunohistochemical marker for renal cell carcinoma in cytopathology

Pax-2 is a homeogene expressed during kidney development. Its expression in renal cell carcinoma (RCC) has been previously evaluated in histologic samples with a high sensitivity and specificity. Here, we investigated the utility of Pax-2 immunohistochemistry (IHC) for RCC in cytologic material, in comparison with a variety of other neoplasms. Pax-2 IHC was performed on cell block sections of 33 RCCs (14 primary, 19 metastatic) and 35 non-RCC malignancies, including 26 carcinomas, five mesenchymal tumors, one neuroblastoma, two melanomas, and one lymphoma, from fine-needle aspirations and body fluids. The presence or absence of nuclear staining and its intensity and distribution in positive cases were evaluated. Of 33 RCCs, Pax-2 was positive in 20 (61%) and negative in 13 (39%). All staining was nuclear, with an admixture of weakly or strongly staining nuclei. Only an endometrial adenocarcinoma was positive in the non-RCC group. The sensitivity and specificity of Pax-2 IHC for RCC were 61 and 97%, respectively. Pax-2 is a moderately sensitive and highly specific marker for RCC in cytologic material, with a lower sensitivity compared with tissue sections, likely due to a patchy expression pattern, and should be included in the immunohistochemical work-up of malignancies.

Nephrogenic adenoma identified on urine cytology using PAX-2 immunostaining

Urine cytology is a sensitive and specific method in detecting urothelial carcinoma of the urinary bladder, particularly the high-grade ones. However, the cytologic features of nonneoplastic lesions of the lower urinary tract, including nephrogenic adenoma, are nonspecific and may cause false positive diagnosis. Recent evidence has demonstrated that nephrogenic adenoma is a true "nephrogenic" lesion derived from the exfoliated and implanted renal tubular cells in the urinary tract. This has promoted the use of immunostaining of renal transcription factor PAX2 in tissue biopsies to differentiate nephrogenic adenoma from the common malignant tumors of the lower urinary tract. We report here that PAX2 immunostaining can also be used in urine cytology specimen to identify nephrogenic adenoma. Combination of PAX2 immunostaining and cytologic analysis may increase the accuracy in identifying this benign lesion in urine cytology specimen and therefore reduce unnecessary repeat cystoscopy and biopsy procedures. This may be a cost effective follow- up method for patients with an established diagnosis of nephrogenic adenoma.