Katayoon Rezaei

Utility of uroplakin II expression as a marker of urothelial carcinoma

Uroplakins are markers of terminally differentiated urothelium. Uroplakin II (UPII) is a newly described sensitive marker for urothelial carcinoma (UC). The expression profile of UPII in different types of UC and its utility in the diagnostic setting are needed. We evaluated UPII expression in bladder tissue microarrays, including urothelial neoplasm of low malignant potential (n = 8), low-grade papillary UC (n = 72), noninvasive high-grade papillary UC (n = 77), UC in situ (n = 27), and invasive high-grade UC (INVUC) (n = 122). UPII expression in 52 breast carcinomas and 38 high-grade prostate adenocarcinomas was also assessed. UPII expression was compared with GATA binding protein 3 (GATA3) and estrogen receptor for its role in facilitating the differential diagnosis of the above 3 types of malignancy. UPII labeling was seen in 83.0% of UC overall, including 95.7% of noninvasive UC and 65.6% of INVUC. UPII labeling was not found in any breast and prostate carcinomas. In comparison, GATA3 labeling was seen in 91.6% of all UCs, including 96.4% of noninvasive UCs and 85.1% of INVUC, with stronger intensity and extent compared with UPII (P < .005). GATA3 labeled 2 (5%) of 38 high-grade prostate adenocarcinoma. Estrogen receptor nuclear labeling was seen in 13.0% of UCs and 12.5% of prostate carcinomas. UPII was highly specific (100%) but only moderately sensitive for UC and can therefore be a potentially useful marker to identify urothelial lineage and help distinguish UC from prostate cancer or, in conjunction with GATA3, from metastatic breast cancer.

A Role for De Novo Purine Metabolic Enzyme PAICS in Bladder Cancer Progression

Genomic and transcriptome sequencing of bladder cancer (BLCA) has identified multiple molecular alterations during cancer progression. Many of these identified genetic and epigenetic changes play a role in the progression of this disease. Studies have identified molecular subtypes in muscle-invasive bladder cancer (MIBC) with different sensitivities to frontline therapy suggesting the heterogeneity in these tumors and the importance of molecular characterization of MIBC to provide effective treatment. Specifically, it has become increasingly evident, as demonstrated by The Cancer Genome Atlas project, that metabolic enzymes are commonly dysregulated in BLCA. Elevated expression of multiple metabolic enzymes is due to the increased demand from rapidly proliferating BLCA cells requiring extensive nucleotide synthesis. Cancer cells utilize the de novo purine and pyrimidine biosynthetic pathway as a source of their nucleotide needs. In this study, we show that phosphoribosyl aminoimidazole succinocarboxamide synthetase (PAICS), an enzyme involved in de novo purine biosynthetic pathway, is significantly overexpressed in BLCA. Immunohistochemical staining of paraffin-embedded tissue sections showed that PAICS is overexpressed in MIBC. Furthermore, we found that tumor suppressor miR-128 negatively regulated PAICS expression by binding to its 3′-untranslated region. We also found that PAICS induces EMT by positively regulating SNAI1 and by a reduction in E-cadherin expression. Additionally, our in vitro functional studies and in vivo chicken chorioallantoic membrane assay show that PAICS plays a critical role in BLCA cell proliferation, invasion, and tumor growth. Collectively, our data suggest that targeting PAICS may provide a therapeutic option in BLCA.

Abstract 1072: miR-671-5p and miR-638 serve as novel biomarkers for early breast cancer detection

Breast cancer progression involves stepwise transition from atypical ductal hyperplasia (ADH), ductal carcinoma in situ (DCIS) to invasive ductal carcinoma (IDC). Percutaneous core needle biopsy (CNB) is the standard procedure after an abnormal mammography finding. However, a CNB diagnosis with either ADH or DCIS is often non-conclusive. A definitive diagnosis relies on surgical excision for further pathological analysis to differentiate simple ADH (sADH) from ADH coexisted with advanced lesions such as DCIS and/or IDC (cADH). Therefore, development of reliable molecular biomarkers is essential to avoid unnecessary surgical excision. microRNAs (miRNAs) are single-stranded non-coding RNAs that play an important role in breast cancer progression. A series of miRNAs that are differentially expressed during stepwise transition of breast carcinogenesis were identified earlier, of which miR-638 and miR-671-5p were functionally characterized. The expression of these miRNAs was decreased gradually from ADH, DCIS, to IDC. We hypothesize that these miRNAs may serve as valuable biomarkers following abnormal mammogram and CNB procedure. Using an improved microdissection protocol, we isolated normal, hyperplasia, DCIS, and/or IDC lesions from FFPE tissue of CNB. We also collected patients’ blood samples before CNB procedure. In addition, we employed the Human 21T breast epithelial cell lines, which were originally derived from the same patient diagnosed with metastatic breast cancer, including H16N2 (normal mammary epithelial), 21PT (ADH), 21NT (DCIS) and 21MT-1 (IDC) for in vitro model study. Real-time qRT-PCR assay was performed for examination of miRNA expression. Cell proliferation and invasion capability were examined by MTT and Transwell assays, respectively after transfection of candidate miRNAs. EMT markers were evaluated by Western blot and Immunofluorescence assays. In clinical samples, we found a synergistic expression pattern between miR-671-5p and miR-638 in cADH but not in sADH lesions. Interestingly, decreased miR-671-5p expression was detected in cADHs, but not in sADHs in both FFPE and serum samples. To explore the potential function of the two miRNAs in the transition from sADH to cADH, we performed further analysis in the Human 21T breast epithelial cell lines. Forced expression of miR-671-5p significantly inhibited cell proliferation in H16N2, 21PT, 21NT and 21MT-1 series cell lines. Overexpression of miR-671-5p attenuated invasion in 21PT, 21NT, and 21MT-1 cell lines but not in H16N2 cell line. Further, miR-671-5p overexpression resulted in significant suppression of mesenchymal marker, vimentin, and promoted the expression of epithelial marker, E-cadherin, in 21PT, 21NT, and 21MT-1cell lines. Our data suggest that miR-671-5p and miR-638 expression in serum and/or CNB tissue may server as a novel companion screening tool following an abnormal mammogram and a subsequent ADH diagnosis by CNB. Citation Format: Xiaohui Tan, Woojin Lee, Xiaoling Wu, Weaam Alshenawy, Danielle Soberman, Katayoon Rezaei, Sana Tabbara, Christine Teal, Robert S. Siegel, Rachel F. Brem, Sidney W. Fu. miR-671-5p and miR-638 serve as novel biomarkers for early breast cancer detection. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1072.

Abstract 3062: miR-671-5p promotes epithelial-to-mesenchymal transition by downregulating FOXM1 expression in breast cancer

microRNA (miRNA) dysfunction is associated with a variety of human diseases including cancer. Our previous study showed that miR-671-5p was deregulated during breast cancer progression. We aim to decipher the functional mechanism of miR-671-5p in breast cancer. We found that expression of miR-671-5p was decreased significantly in ductal carcinoma in situ (DCIS) and invasive ductal carcinoma (IDC) compared to normal and atypical ductal hyperplasia (ADH) in the microdissected formalin-fixed, paraffin-embedded (FFPE) tissues. Forkhead Box M1 (FOXM1), as an oncogenic transcription factor, was predicted as one of the direct targets of miR-671-5p, which was subsequently confirmed by luciferase assays. Forced expression of miR-671-5p in breast cancer cell lines downregulated FOXM1 expression, and attenuated the proliferation and invasion in breast cancer cell lines. Notably, overexpression of miR-671-5p resulted in a shift from epithelial-to-mesenchymal transition (EMT) to mesenchymal-to-epithelial transition (MET) phenotypes in MDA-MB-231 breast cancer cells and induced S-phase arrest. Moreover, miR-671-5p sensitized breast cancer cells to cisplatin, 5-fluorouracil (5-FU) and epirubicin exposure. Host cell reactivation (HCR) assays showed that miR-671-5p reduces DNA repair capability in post-drug exposed breast cancer cells. These data indicates that miR-671-5p functions as a tumor suppressor miRNA by directly targeting FOXM1 in breast cancer. Hence, miR-671-5p may serve as a novel therapeutic target for breast cancer management. Citation Format: Xiaohui Tan, Yebo Fu, Liang Chen, Shejuan An, Woojin Lee, Yinglei Lai, Katayoon Rezaei, Sana Tabbara, Christine B. Teal, Yan-gao Man, Robert Siegel, Rachel F. Brem, Sidney W. Fu. miR-671-5p promotes epithelial-to-mesenchymal transition by downregulating FOXM1 expression in breast cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3062. doi:10.1158/1538-7445.AM2015-3062