Chunyan Luan

A Molecular Classification of Papillary Renal Cell Carcinoma

Despite the moderate incidence of papillary renal cell carcinoma (PRCC), there is a disproportionately limited understanding of its underlying genetic programs. There is no effective therapy for metastatic PRCC, and patients are often excluded from kidney cancer trials. A morphologic classification of PRCC into type 1 and 2 tumors has been recently proposed, but its biological relevance remains uncertain. We studied the gene expression profiles of 34 cases of PRCC using Affymetrix HGU133 Plus 2.0 arrays (54,675 probe sets) using both unsupervised and supervised analyses. Comparative genomic microarray analysis was used to infer cytogenetic aberrations, and pathways were ranked with a curated database. Expression of selected genes was validated by immunohistochemistry in 34 samples with 15 independent tumors. We identified two highly distinct molecular PRCC subclasses with morphologic correlation. The first class, with excellent survival, corresponded to three histologic subtypes: type 1, low-grade type 2, and mixed type 1/low-grade type 2 tumors. The second class, with poor survival, corresponded to high-grade type 2 tumors (n = 11). Dysregulation of G1-S and G2-M checkpoint genes were found in class 1 and 2 tumors, respectively, alongside characteristic chromosomal aberrations. We identified a seven-transcript predictor that classified samples on cross-validation with 97% accuracy. Immunohistochemistry confirmed high expression of cytokeratin 7 in class 1 tumors and of topoisomerase IIalpha in class 2 tumors. We report two molecular subclasses of PRCC, which are biologically and clinically distinct and may be readily distinguished in a clinical setting.

Glypican 3: A novel marker in testicular germ cell tumors

Glypican 3 (GPC3), a membrane-bound heparin sulfate proteoglycan, may play a role in promoting embryonic cell growth and differentiation. GPC3 is mutated in Simpson-Golabi-Behmel syndrome, characterized by tissue overgrowth and an increased risk of embryonal malignancies. Recently, GPC3 was reported to be one of the over-expressed genes in testicular yolk sac tumors by gene expression microarray analysis. However, the presence of the GPC3 protein in germ cell tumors has never been investigated. The purpose of the study was to investigate the GPC3 expression in various histologic components of testicular germ cell tumors using immunohistochemistry and to assess its possible utility as a diagnostic marker. Tumors from 71 patients were examined, including components of 42 seminomas, 37 embryonal carcinomas, 24 yolk sac tumors, 20 teratomas with mature elements, 16 teratomas with immature elements, and 7 choriocarcinomas. Cytoplasmic and membranous immunoreactivity was semiquantitatively evaluated. All yolk sac tumor (24/24) and choriocarcinoma (7/7) components were immunoreactive for GPC3, whereas only 38% of teratomas with immature elements and 8% of embryonal carcinomas expressed GPC3. There was no immunoreactivity in benign testicular tissue, intratubular germ cell neoplasia, seminomas (0/42), or teratomas with mature elements (0/20). We conclude that the oncofetal protein GPC3 is a novel immunohistochemical marker in testicular germ cell tumors with differential expression in defined histologic subtypes. Our findings suggest a possible role of GPC3 in tumor cell differentiation. Furthermore, GPC immunostaining may be useful in the pathologic diagnosis of nonseminomatous germ cell tumors, particularly yolk sac tumor, and choriocarcinoma.

Benign metastasizing leiomyoma: clonality, telomere length and clinicopathologic analysis.

Benign metastasizing leiomyoma is a rare condition affecting women with a history of uterine leiomyomata and is characterized by multiple histologically benign pulmonary smooth muscle tumors. Speculations on its pathogenesis include a benign uterine leiomyoma colonizing the lung, a metastatic low-grade uterine leiomyosarcoma, and primary pulmonary leiomyomatosis. To elucidate its pathogenesis, we analyzed the clinical, pathological and immunohistochemical features, clonality, and telomere length of multiple lung and uterine tumors in three patients with benign metastasizing leiomyoma. In all cases, pulmonary tumors had benign histology and immunohistochemical profiles (estrogen receptor positive, progesterone receptor positive, and very low proliferative index) identical to uterine leiomyoma. In eight tumors from three patients, clonality was assessed by analyzing the variable length of the polymorphic CAG repeat sequence within the human androgen receptor gene. In the two informative patients pulmonary and uterine tumors showed identical patterns of androgen receptor allelic inactivation, indicating that they were clonal. The telomere length measured by fluorescence in situ hybridization in pulmonary leiomyomas of all three patients were either long or very long and were identical to the uterine counterparts, indicating significant telomere shortening is not a crucial step for developing metastases. Our evidence supports the notion that benign metastasizing leiomyoma is clonally derived from benign-appearing uterine leiomyomas.

αB-crystallin: A novel marker of invasive basal-like and metaplastic breast carcinomas

Basal-like tumors are a newly recognized estrogen receptor (ER) negative and HER2 negative breast cancer subtype that express basal epithelial genes and are associated with poor survival. Metaplastic carcinomas are thought to belong within the basal-like group. We have recently demonstrated that the small heat shock protein alphaB-crystallin is commonly expressed in basal-like tumors and contributes to their aggressive phenotype. The current study examined the rates and patterns of alphaB-crystallin expression in whole tissue sections of human breast, including normal tissue, proliferative lesions, in situ and invasive carcinomas (ER positive, HER2 positive, basal-like, and metaplastic cancers). In normal breast tissue, proliferative lesions and in situ carcinomas, alphaB-crystallin expression was restricted to the myoepithelial cell compartment of ductal and lobular units. Most basal-like and metaplastic carcinomas demonstrated cytoplasmic expression of alphaB-crystallin (81% and 86%, respectively). Conversely, no staining for alphaB-crystallin was observed in nonbasal-like (ie, ER positive or HER2 positive) breast carcinomas. Taken together, our results indicate that alphaB-crystallin is a sensitive (81%) and specific (100%) marker for basal-like breast carcinomas. Moreover, the high rates of expression of alphaB-crystallin in metaplastic breast carcinomas (86%) suggest that these tumors may represent a histologically distinctive subset of basal-like breast tumors with a similar underlying molecular etiology.

Glypican 3 has a higher sensitivity than alpha-fetoprotein for testicular and ovarian yolk sac tumour: immunohistochemical investigation with analysis of histological growth patterns.

Zynger D L, McCallum J C, Luan C, Chou P M & Yang X J
(2010) Histopathology 56, 750–757
Glypican 3 has a higher sensitivity than alpha‐fetoprotein for testicular and ovarian yolk sac tumour: immunohistochemical investigation with analysis of histological growth patterns

HMGA2: A Potential Biomarker Complement to P53 for Detection of Early-stage High-grade Papillary Serous Carcinoma in Fallopian Tubes

Before high-grade papillary serous carcinoma (HG-PSC) becomes invasive, it is believed to be a poorly defined short-lived precursor lesion. A recent characterization of serous tubal intraepithelial carcinoma (STIC) and of the p53 signature suggested that HG-PSC may follow a stepwise progression on cellular and molecular levels. High-mobility group AT-hook 2 (HMGA2), an oncofetal protein, is overexpressed in ovarian cancer. To test whether HMGA2 can be another valuable marker for STIC, we examined HMGA2 expression in 3 groups of patients: (1) 24 patients with STIC and its invasive counterpart, HG-PSC of the fallopian tubes, (2) 24 patients with HG-PSC of the ovaries but without STIC (positive control), and (3) 30 patients with cancer and normal fallopian tubes (negative control). We found that HMGA2 was overexpressed in 75% of patients with STIC, was coexpressed with p53 in more than 50% of patients, and was completely negative in the secretory cells of the 30 patients with normal fallopian tubes. Among 7 patients with cells negative for p53 staining, HMGA2 was positive in 5; among 6 patients whose tumor cells were negative for HMGA2 in STIC, 3 were positive for HMGA2 in the invasive component; about 70% of invasive HG-PSC tumor cells were immunoreactive for both HMGA2 and TP53. In invasive carcinoma, HMGA2 overexpression was correlated with p53 (r=0.45), indicating the role of HMGA2 in p53 mediated tumor progression. Our findings of immunoreactivity for HMGA2 may lead to a novel, useful biomarker to complement p53 in the detection of early-stage serous carcinoma.

Expression of kidney-specific cadherin in chromophobe renal cell carcinoma and renal oncocytoma

Kidney-specific cadherin (Ksp-cad) recently was proposed to differentiate chromophobe renal cell carcinoma (RCC) from oncocytoma based on a finding of Ksp-cad expression in 97% of chromophobe RCCs but only 3% of oncocytomas. However, another study showed no difference in Ksp-cad immunoreactivity between these 2 tumors. We attempted to evaluate Ksp-cad expression in renal tumors using expression microarrays and immunohistochemical analysis. Ksp-cad messenger RNA (mRNA) levels were examined in 158 renal tumors, including 15 chromophobe RCCs and 15 oncocytomas. Immunohistochemical analysis was performed on tissue microarrays containing 125 renal tumors, including 36 chromophobe RCCs and 41 oncocytomas. Ksp-cad mRNA compared with normal kidney tissue was 89% in chromophobe RCC and 64% in oncocytoma. Furthermore, 31 of 36 chromophobe RCCs and 31 of 41 oncocytomas showed Ksp-cad immunoreactivity. Ksp-cad was present in chromophobe RCCs and oncocytomas at mRNA and protein levels, providing strong evidence that Ksp-cad immunohistochemical analysis cannot be used in differentiating these tumors.

Expression Analysis of Putative Stem Cell Markers in Human Benign and Malignant Prostate

Stem cells were suggested to be present in human prostate cancer as a small population of distinct cells, which may contribute to carcinogenesis, tumor recurrence, and chemoresistance. To identify potential prostatic stem cells, we analyzed the expression of several potential stem cell markers in benign prostate and prostatic adenocarcinoma.

FXYD3: A Promising Biomarker for Urothelial Carcinoma

Objective Urothelial carcinoma (UC) of the kidney is a relatively rare but aggressive form of kidney cancer. Differential diagnosis of renal UC from renal cell carcinoma (RCC) can be difficult, but is critical for correct patient management. We aimed to use global gene expression profiling to identify genes specifically expressed in urothelial carcinoma (UC) of the kidney, with purpose of finding new biomarkers for differential diagnosis of UC of both upper and lower tract from normal tissues. Materials and Methods Microarray gene expression profiling was performed on a variety of human kidney tumor samples, including clear cell, papillary, chromophobe, oncocytoma, renal UC and normal kidney controls. Differentially expressed mRNAs in various kidney tumor subtypes were thus identified. Protein expression in human UC tumor samples from both upper and lower urinary tract was evaluated by immunohistochemistry. Results FXYD3 (MAT-8) mRNA was specifically expressed in UC of the kidney and not in normal kidney tissue or in any RCC tumor subtypes. FXYD3 mRNA levels displayed equal or better prediction rate for the detection of renal UC than the mRNA levels of selected known UC markers as p63, vimentin, S100P, KRT20 and KRT7. Finally, immunohistochemical staining of clinical UC samples showed that FXYD3 protein is overexpressed in majority of UC of the upper genitourinary tract (encompassing the kidney, ~90%) and in majority of high grade bladder UC (~84%, its < 40% in low grade tumors, P < 0.001) compared to normal kidney and bladder tissues. Conclusion FXYD3 may be a promising novel biomarker for the differential diagnosis of renal UC and a promising prognosis marker of UC from bladder. Because it was identified genome-widely, FXYD3 may have important biological ramifications for the genetic study of UC.