Loss Of PAX2 Expression Research Articles

Retained PAX2 expression associated with DNA mismatch repair deficiency in endometrial endometrioid adenocarcinoma.

Loss of expression of tumour suppressor PAX2 and MMR deficiency (dMMR) has been frequently seen in endometrial endometrioid adenocarcinoma (EEC). However, the relationship between PAX2 expression and MMR status is unknown. We studied the PAX2 expression and examined its association with MMR status at the protein and genetic levels in 180 cases of EEC. Overall, total loss of PAX2 expression was found in about 70%, while retained PAX2 expression was seen in 30% of EEC. Among 125 cases with loss of PAX2, 68.8% were found in EECs with pMMR, while 31.2% were seen in those with dMMR. Among 55 cases of EECs with retained PAX2 expression, 92.7% were EECs with dMMR and 7.3% were those with pMMR (P < 0.001). While dMMR cases with MLH1 hypermethylation show almost equal retained or loss of PAX2 expression (52% versus 48%), dMMR with genetic alterations had significantly more retained PAX2 expression than loss of PAX2 (92.3% versus 7.7%), regardless of somatic or germline mutations. Loss of PAX2 was observed in 97.3% of dMMR with MLH1 hypermethylation compared to 2.7% of dMMR with genetic alterations (P < 0.001). Aggressive features such as higher tumour grades (FIGO 2-3) and advanced clinical stage (T2-T4) were significantly more frequently seen in dMMR with retained PAX2 expression, compared those to pMMR with loss of PAX2 expression. Our study demonstrates a close correlation between retained PAX2 expression and dMMR in EEC. The molecular mechanism and clinical significance linking these two pathways in EEC remains to be unravelled.

Malignant transformation of endometrial hyperplastic processes: immunohistochemical features

Background. Endometrial hyperplasia is one of the most common pathologies of the female reproductive system. There is a high risk of transformation of an atypical form of endometrial hyperplasia into endometrial cancer, which takes a leading position in oncogynecological morbidity. Immunohistochemical markers can become predictors of endometrial malignancy, their role is currently being actively studied.Aim. Search for molecular predictors of malignant transformation of endometrial hyperplasia.Materials and methods. Histological and immunohistochemical studies were performed in 107 patients with diagnoses of endometrial hyperplasia without atypia (EH), endometrial atypical hyperplasia (EIN), endometrioid adenocarcinoma (EC). The tumor receptor status, MSI, expression of ARID1A, PTEN, β-catenin, PAX2, proliferation index (Ki-67) were determined by the immunohistochemical method according to the standard protocol.Results. Loss of PAX2 expression was most common in precancerous and malignant endometrial cells. Loss of PAX2 expression was found in 89 % of cases in the EIN samples, in 86 % of cases in the EC samples and only in 2 cases of EH. Loss of PTEN expression was less common: with an equal proportion in 67 % of the samples of EIN and EC, while practically not occurring in women with benign GE. MSI was detected in 36 % of endometrial cancer samples. There was a deficiency in the DNA repair system in 1 case of EIN. Loss of ARID1A expression was detected in endometrial cancer with a frequency of 33 %. This gene functioned normally in all cases of EIN and EH. The expression of β-catenin was more pronounced in EC than in cases of EH. The Ki-67 proliferation index was statistically higher in the EC group than in EH and EIN.Conclusion. Evaluation of morphological data and expression of the panel of markers PAX2, PTEN, ARID1A, β-catenin, Ki-67 index, PMS2 and MLH1 will improve diagnostic search in case of suspected malignancy of endometrial hyperplasia.

Expression of PAX2 and PTEN in Oestrogen-Driven Endometrial Hyperplasia and Neoplasia

Endometrial hyperplasia is of paramount clinical implication as it is usually seen to precede endometrioid adenocarcinoma. However, clinicians and pathologists have always been uncertain about the distinction between innocuous hyperplasia from their sinister counterparts. This has serious implications, for the latter lesion has a greater propensity for progressing into adenocarcinoma and needs deft clinical intervention in the form of adequate progestational exposure or surgery. Thirty cases diagnosed as endometrial hyperplasia on endometrial biopsies were retrieved from the archives and reclassified as per the EIN criteria. Thirty cases each of proliferative endometrium and endometrioid carcinoma were also included. Immunohistochemistry with antibodies against PAX2 and PTEN was performed, and the extent of loss of expression was scored. A total of ten cases of EIN were identified, all of whom were initially diagnosed as complex hyperplasia with atypia. All cases of proliferative endometrium showed retained expression of PAX2 and PTEN. In contrast, all cases of endometrioid carcinoma showed complete loss of PAX2 and PTEN. The EIN cases showed partial loss of both PAX2 and PTEN expression. Loss of PAX2 expression in EIN showed a specificity and positive predictive value of 90% and 83.33%, respectively. The advent of the EIN criteria has made identification of clinically significant endometrial precancerous lesion more acceptable and reproducible. However, in cases of ambiguity, the use of antibodies against certain protein molecules which reflect the genes involved in the stepwise carcinogenesis would be of great utility in the hands of the pathologist. In comparison with PTEN, the use of PAX2, which gives a crisp nuclear positivity and has a lower percentage of loss of expression in normal endometrium, can be used as part of the algorithm in accurately identifying the precancerous endometrium.

PAX2 maintains the differentiation of mouse oviductal epithelium and inhibits the transition to a stem cell-like state.

Recent studies have provided evidence that the secretory cells of the fallopian tube (oviduct) are a probable origin for high-grade serous ovarian carcinoma. In addition to secretory cells, the fallopian tube epithelium consists of ciliated cells and CD44+ undifferentiated stem-like cells. Loss of PAX2 expression is recognized as an early event in epithelial transformation, but the specific role of PAX2 in this transition is unknown. The aim of this study was to define the role of PAX2 in oviductal epithelial (OVE) cells and its response to transforming growth factor β1 (TGFβ), characterizing specifically its potential involvement in regulating stem cell-like behaviors that may contribute to formation of cancer-initiating cells. Treatment of primary cultures of mouse OVE cells with TGFβ induced an epithelial-mesenchymal transition (EMT) associated with decreased expression of PAX2 and an increase in the fraction of cells expressing CD44. PAX2 knockdown in OVE cells and overexpression in ovarian epithelial cells confirmed that PAX2 inhibits stem cell characteristics and regulates the degree of epithelial differentiation of OVE cells. These results suggest that loss of PAX2, as occurs in serous tubal intraepithelial carcinomas, may shift secretory cells to a more mesenchymal phenotype associated with stem-like features.

Expansion of secretory cells in the fallopian tubal epithelium in the early stages of the pathogenesis of ovarian serous carcinomas

to investigate the frequency of the types of fallopian tubal secretory cell expansion (SCE) in diseases of the reproductive organs and to determine the immunophenotype and biological role of the cells in the early stages of the pathogenesis of high-grade ovarian serous carcinomas (HGOSC). The investigation enrolled 287 patients with extraovarian diseases and ovarian serous tumors varying in grade, whose fallopian tubes were morphologically and immunohistochemically examined using p53, Ki-67, PAX2, Bcl-2, beta-catenin, and ALDH1 markers. The material was statistically processed applying the Mann-Whitney test and χ2 test. The rate of secretory cell proliferation (SCP) (more than 10 consecutive secretory cells) and that of secretory cell overgrowth (SCO) (more than 30 consecutive secretory cells) increase with age in all investigated reproductive system diseases. The rate of SCP in the corpus fimbriatum of the patients with HGOSC was 5.9 times higher than that in those with extraovarian disease (p<0.01); when comparing the same patient groups, that of SCO was 3.4 times higher (p<0.05). The immunohistochemical characteristics of the investigated lesions (in scores) were as follows: PAX2 was expressed in the intact epithelium (2.8), in SCP (1.3), in SCO (1.2), in serous tubal intraepithelial carcinoma (STIC) (1.0), and in HGOSC (0.9); Bcl-2 was in the intact epithelium (2.2), in SCP (2.1), STIC (0.9), and in HGOSC (0.6), β-catenin was in the intact epithelium (0.5), in SCP (2.85), in SCO (2.95), in STIC (0.6), and in HGOSC (0.5); ALDH1 was in the intact epithelium (0.5), in SCP (2.91), in SCO (2.92), in STIC (1.2), and in HGOSC (0.6). There were statistically significant differences with a 95% confidence interval (p<0.05) for: 1) PAX2 between the intact epithelium and pathology (fallopian tube lesions and HGOSC); 2) Bcl-2 between the intact epithelium and SCE (SCP and SCO) and between SCE and HGOSC; 3) beta-catenin between the intact epithelium and SCE (SCP and SCO) and between SCE and HGOSC; 4) ALDH1 between the intact epithelium and SCE, between and SCE and STIC, and between STIC and HGOSC. SCE was shown to be an independent intraepithelial lesion. The incidence of this abnormality increased with age and significantly differed in the patients with fallopian tubal lesions in extraovarian diseases from that in those with malignant ovarian serous tumors (by 5.3 times), while these groups showed a three-fold difference in SCO. Thus, SCP may serve as a more sensitive marker for the early stages of the pathogenesis of ovarian serous carcinoma. The studied types of SCE demonstrated multiple molecular events (loss of PAX2 expression and increased Bcl-2, beta-catenin, and ALDH1 expressions), some of which underwent considerable changes, by increasing the severity of a pathological process (loss of ALDH1, and beta-catenin, and bcl-2 expressions). Thus, therapeutic exposure in the early stages of pathogenesis may have a few points of application and just several molecules can serve as independent markers for early pathological changes in the fallopian tubal epithelium.

Abstract 104: PAX2 dysregulation in the fallopian tube and pelvic serous cancer

Abstract High grade ovarian serous cancer in women has been linked to the distal fallopian tube via a carcinogenic sequence of p53 mutations in both a clonally-derived precursor (p53 signature) and an early malignancy (tubal intraepithelial carcinoma)(Lee 2007). Dysregulation of additional genes, including PTEN and PAX2, has been associated with this early carcinogenic sequence and advanced ovarian serous cancers. Dysregulation of PAX2 has not been linked to genetic mutations, and has been recently documented throughout the tube within discrete secretory cell outgrowths (SCOUTs), particularly in fallopian tubes of women with serous cancer (Chen 2010). This study explored the frequency of PAX2-null SCOUTs in the fallopian tube and other potential molecular and cell kinetic correlates of this phenomenon. Fallopian tubes from a wide range of subjects, including (1) pre-adolescents (n=20), women undergoing (2) post-partum tubal ligation (n=25), (3) salpingectomy during surgery for benign disease (n=20), surgery for (4) endometriosis (n=47), (5) low grade endometrioid adenocarcinomas of the ovary (n=42), and (6) high-grade ovarian serous carcinomas (n=12) were immunostained and scored blindly for PAX2-null SCOUTs. Extracted tubal DNA from cancers and controls was analyzed for hypermethylation of the PAX2 promotor by real-time PCR and fallopian tube epithelial cultures were established from cancers and controls to assess clonogenic capacity. Review of over 350 tissue blocks revealed a frequency (%) of PAX2-null SCOUTs of 0, 0.5, 11, 5, 4.5 and 56.2 for groups 1-6 above, respectively, yielding a 5-50-fold increase in the tubes of patients with serous cancer (p &amp;lt; .001). A preliminary analysis of DNA from one cancer-associated fallopian tube revealed a relative increase in PAX2 promotor methylation. A striking increase in cell growth (clonogenic) capacity was observed in tubes from cancer patients versus controls. This study reveals, for the first time, that functional loss of PAX2 expression is linked to a morphologically defined entity (SCOUT) in the fallopian tube that is absent in pre-adolescent fallopian tubes and post-partum tubal ligations, increases with age, and is exquisitely linked to co-existing high grade ovarian serous carcinoma. This unique dysregulation of PAX2 appears to segregate with a markedly higher in vitro clonogenic potential of tubal epithelium in women with serous cancer. The potential that this highly prevalent entity (PAX2-null SCOUT) and its milieu in fallopian tube epithelium of women with serous cancer can be exploited as a predictor of concurrent or future ovarian serous carcinoma is under investigation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 104. doi:10.1158/1538-7445.AM2011-104

Ectopic Pax2 expression in chick ventral optic cup phenocopies loss of Pax2 expression

Pax2 is essential for the development of the urogenital system, neural tube, otic vesicle, optic cup and optic tract [Dressler, G.R., Deutsch, U., et al., 1990. PAX2, a new murine paired-box-containing gene and its expression in the developing excretory system. Development 109 (4), 787–795; Nornes, H.O., Dressler, G.R., et al., 1990. Spatially and temporally restricted expression of Pax2 during murine neurogenesis. Development 109 (4), 797–809; Eccles, M.R., Wallis, L.J., et al., 1992. Expression of the PAX2 gene in human fetal kidney and Wilms’ tumor. Cell Growth Differ 3 (5), 279–289]. Within the visual system, a loss-of-function leads to lack of choroid fissure closure (known as a coloboma), a loss of optic nerve astrocytes, and anomalous axonal pathfinding at the optic chiasm [Favor, J., Sandulache, R., et al., 1996. The mouse Pax2(1Neu) mutation is identical to a human PAX2 mutation in a family with renal-coloboma syndrome and results in developmental defects of the brain, ear, eye, and kidney. Proc. Natl. Acad. Sci. U. S. A. 93 (24), 13870–13875; Torres, M., Gomez-Pardo, E., et al., 1996. Pax2 contributes to inner ear patterning and optic nerve trajectory. Development 122 (11), 3381–3391]. This study is directed at determining the effects of ectopic Pax2 expression in the chick ventral optic cup past the normal developmental period when Pax2 is found. In ovo electroporation of Pax2 into the chick ventral optic cup results in the formation of colobomas, a condition typically associated with a loss of Pax2 expression. While the overexpression of Pax2 appears to phenocopy a loss of Pax2, the mechanism of the failure of choroid fissure closure is associated with a cell fate switch from ventral retina and retinal pigmented epithelium (RPE) to an astrocyte fate. Further, ectopic expression of Pax2 in RPE appears to have non-cell autonomous effects on adjacent RPE, creating an ectopic neural retina in place of the RPE.

Immunohistochemical Analysis for Cytokeratin 7, KIT, and PAX2

Immunohistochemical staining for cytokeratin 7 (CK7), KIT, and PAX2 expression was performed on 91 renal neoplasms, 37 conventional (clear cell) renal cell carcinomas (CRCCs), 20 papillary RCCs (PRCCs), 11 chromophobe RCCs (ChCs), and 23 oncocytomas, with available karyotypes. All ChCs, 19 PRCCs, 2 CRCCs, and 1 oncocytoma were CK7+; all ChCs, 22 oncocytomas, 2 CRCCs, and no PRCCs expressed KIT; PAX2 was positive in 31 CRCCs, 17 PRCCs, 20 oncocytomas, and 1 ChC. The predominant expression profiles were as follows: CRCC, CK7-/KIT-/PAX2+ (26/37); PRCC, CK7+/KIT-/PAX2+ (17/20); ChC, CK7+/KIT+/PAX2- (10/11); and oncocytoma, CK7-/KIT+/PAX2+ (19/23). Cytogenetic analysis showed that the sole PAX2+ ChC had a retained chromosome 10, and all ChCs with chromosome 10 loss were PAX2-. These results identify specific staining patterns of the 4 major histologic subtypes of renal neoplasms and raise the question of a relationship between chromosome 10 loss and loss of PAX2 expression in ChC.