Ximing J. Yang

Small cell carcinoma of the urinary bladder: A clinicopathologic analysis of 64 patients

Small cell carcinoma of the urinary bladder is an uncommon tumor that has been described in case reports or small series. Herein, the authors report a series of 64 patients with small cell carcinoma of the urinary bladder.

Tumor Evasion of the Immune System by Converting CD4+CD25− T Cells into CD4+CD25+ T Regulatory Cells: Role of Tumor-Derived TGF-β

CD4+CD25+ T regulatory (Treg) cells were initially described for their ability to suppress autoimmune diseases in animal models. An emerging interest is the potential role of Treg cells in cancer development and progression because they have been shown to suppress antitumor immunity. In this study, CD4+CD25− T cells cultured in conditioned medium (CM) derived from tumor cells, RENCA or TRAMP-C2, possess similar characteristics as those of naturally occurring Treg cells, including expression of Foxp3, a crucial transcription factor of Treg cells, production of low levels of IL-2, high levels of IL-10 and TGF-β, and the ability to suppress CD4+CD25− T cell proliferation. Further investigation revealed a critical role of tumor-derived TGF-β in converting CD4+CD25− T cells into Treg cells because a neutralizing Ab against TGF-β, 1D11, completely abrogated the induction of Treg cells. CM from a nontumorigenic cell line, NRP-152, or irradiated tumor cells did not convert CD4+CD25− T cells to Treg cells because they produce low levels of TGF-β in CM. Finally, we observed a reduced tumor burden in animals receiving 1D11. The reduction in tumor burden correlated with a decrease in tumor-derived TGF-β. Treatment of 1D11 also reduced the conversion of CD4+ T cells into Treg cells and subsequent Treg cell-mediated suppression of antitumor immunity. In summary, we have demonstrated that tumor cells directly convert CD4+CD25− T cells to Treg cells through production of high levels of TGF-β, suggesting a possible mechanism through which tumor cells evade the immune system.

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.

Loss of Parafibromin Immunoreactivity Is a Distinguishing Feature of Parathyroid Carcinoma

Purpose: A reliable method for diagnosing parathyroid carcinoma has remained elusive over the years, resulting in its under-recognition and suboptimal therapy. Obtaining an accurate diagnosis has become an even more pressing matter with recent evidence that germline HRPT2 gene mutations are found in patients with apparently sporadic parathyroid carcinoma. There is a high prevalence of HRPT2 gene mutations and biallelic inactivation in parathyroid carcinoma. We hypothesize that loss of parafibromin, the protein product of the HRPT2 gene, would distinguish carcinoma from benign tissue. Experimental Design: We generated a novel antiparafibromin monoclonal antibody and performed immunostaining on 52 definite carcinoma specimens, 6 equivocal carcinoma specimens, 88 benign specimens, and 9 hyperparathyroidism-jaw tumor (HPT-JT) syndrome-related adenomas from patients with primary hyperparathyroidism from nine worldwide centers and one national database. Results: We report that the loss of parafibromin nuclear immunoreactivity has 96% sensitivity [95% confidence interval (CI), 85–99%] and 99% specificity (95% CI, 92–100%) in diagnosing definite carcinoma. Inter-observer agreement for evaluation of parafibromin loss was excellent, with unweighted kappa of 0.89 (95% CI, 0.79–0.98). Two equivocal carcinomas misclassified as adenomas were highlighted by parafibromin immunostaining. One of these tumors has since recurred, satisfying criteria for a definite carcinoma. Similarly, eight of nine HPT-JT syndrome-related adenomas showed absent nuclear immunoreactivity. Conclusions: Parafibromin is a promising molecular marker for diagnosing parathyroid carcinoma. The similar loss of parafibromin immunoreactivity in HPT-JT syndrome-related adenomas suggests that this is a pivotal step in parathyroid tumorigenesis.

Expression of Alpha-Methylacyl-CoA Racemase in Papillary Renal Cell Carcinoma

Alpha-methylacyl-CoA racemase (AMACR) was first discovered by using cDNA microarray technology as a molecular marker for prostate cancer. Our recent microarray analysis of renal cell carcinomas showed a significant increase of AMACR mRNA levels in papillary renal cell carcinomas, but not in other subtypes. To investigate the value of this marker in pathologic diagnosis, we analyzed AMACR mRNA levels in cDNA microarrays from 70 kidney tumors. Furthermore, we evaluated the AMACR expression in 165 kidney tumors on tissue microarrays and 51 papillary carcinomas of other organs by immunohistochemistry. AMACR mRNA was significantly overexpressed in 7 of 8 papillary renal cell carcinomas with an average of 5.2-fold increase, and only in 2 of 62 nonpapillary kidney tumors. Immunohistochemistry demonstrated strong AMACR positivity in all cases of papillary renal cell carcinomas (41 of 41, 100%), including 6 metastatic papillary renal cell carcinomas, but only focal or weak reactivity in the minority (18 of 124, 15%) of other renal tumors including 13 of 52 clear cell renal cell carcinomas, 3 of 20 oncocytomas, and 2 of 17 urothelial carcinomas. All chromophobe (0 of 18) and sarcomatoid components of renal cell carcinomas (0 of 15) were negative for AMACR. Weak or focal AMACR immunoreactivity was detected in only 4 of 51 (8%) papillary carcinomas arising in other organs (2 of 14 thyroid, 2 of 13 lung, 0 of 6 breast, 0 of 6 endometrium, 0 of 6 ovary, and 0 of 6 pancreas). Using a combination of cDNA microarrays, tissue microarrays, and immunohistochemistry, we identified AMACR as a marker for papillary renal cell carcinoma, which could be valuable in subclassification of renal cell carcinomas and in the differential diagnosis of a metastatic papillary carcinoma.

Molecular Genetic Evidence for a Common Clonal Origin of Urinary Bladder Small Cell Carcinoma and Coexisting Urothelial Carcinoma

In most cases, small-cell carcinoma of the urinary bladder is admixed with other histological types of bladder carcinoma. To understand the pathogenetic relationship between the two tumor types, we analyzed histologically distinct tumor cell populations from the same patient for loss of heterozygosity (LOH) and X chromosome inactivation (in female patients). We examined five polymorphic microsatellite markers located on chromosome 3p25-26 (D3S3050), chromosome 9p21 (IFNA and D9S171), chromosome 9q32-33 (D9S177), and chromosome 17p13 (TP53) in 20 patients with small-cell carcinoma of the urinary bladder and concurrent urothelial carcinoma. DNA samples were prepared from formalin-fixed, paraffin-embedded tissue sections using laser-assisted microdissection. A nearly identical pattern of allelic loss was observed in the two tumor types in all cases, with an overall frequency of allelic loss of 90% (18 of 20 cases). Three patients showed different allelic loss patterns in the two tumor types at a single locus; however, the LOH patterns at the remaining loci were identical. Similarly, the same pattern of nonrandom X chromosome inactivation was present in both carcinoma components in the four cases analyzed. Concordant genetic alterations and X chromosome inactivation between small-cell carcinoma and coexisting urothelial carcinoma suggest that both tumor components originate from the same cells in the urothelium.

Small cell carcinoma of the prostate: An immunohistochemical study

Small cell carcinoma of the prostate (SCPC) is morphologically similar to small cell carcinoma of the lung (SCLC) and maybe misinterpreted as Gleason pattern 5b prostate adenocarcinoma (HGPC). Recognition of SCPC is important because of its different clinical behavior. This study aims to characterize the immunophenotype of histologically classic SCPC using a comprehensive panel of markers, to better understand its histogenesis, aid in its classification, and evaluate potential therapeutic targets. Using the World Health Organization morphologic criteria for SCLC, 18 SCPC cases were identified; and studied for the following tumor marker groups: prostate specific/related, neuroendocrine, sex steroid hormone receptors, and prognostic/treatment target-related. Ten cases of UPC were used as controls. PSA was positive in 17% of SCPC and neuroendocrine markers were expressed in HGPC. PSA, TTF-1 and CD56 were the most helpful markers in differentiating between SCPC and HGPC (P<0.01), whereas bombesin/GRP, c-kit, bcl-2, and EGFR expression was more frequent in SCPC. SCPC is best diagnosed by following the World Health Organization diagnostic criteria for SCLC. Immunohistochemical markers can help separate SCPC from HGPC and may be useful in histologically borderline cases. Potential therapeutic targets are identified immunohistochemically in SCPC (Bombesin/GRP, c-kit, bcl-2, and EGFR).

Adoptive Transfer of Tumor-Reactive Transforming Growth Factor-β–Insensitive CD8+ T Cells: Eradication of Autologous Mouse Prostate Cancer

Transforming growth factor (TGF)-beta is a potent immunosuppressant. Overproduction of TGF-beta by tumor cells may lead to tumor evasion from the host immune surveillance and tumor progression. The present study was conducted to develop a treatment strategy through adoptive transfer of tumor-reactive TGF-beta-insensitive CD8+ T cells. The mouse TRAMP-C2 prostate cancer cells produced large amounts of TGF-beta1 and were used as an experimental model. C57BL/6 mice were primed with irradiated TRAMP-C2 cells. CD8+ T cells were isolated from the spleen of primed animals, were expanded ex vivo, and were rendered TGF-beta insensitive by infecting with a retrovirus containing dominant-negative TGF-beta type II receptor. Results of in vitro cytotoxic assay revealed that these CD8+ T cells showed a specific and robust tumor-killing activity against TRAMP-C2 cells but were ineffective against an irrelevant tumor line, B16-F10. To determine the in vivo antitumor activity, recipient mice were challenged with a single injection of TRAMP-C2 cells for a period up to 21 days before adoptive transfer of CD8+ T cells was done. Pulmonary metastasis was either eliminated or significantly reduced in the group receiving adoptive transfer of tumor-reactive TGF-beta-insensitive CD8+ T cells. Results of immunofluorescent studies showed that only tumor-reactive TGF-beta-insensitive CD8+ T cells were able to infiltrate into the tumor and mediate apoptosis in tumor cells. Furthermore, transferred tumor-reactive TGF-beta-insensitive CD8+ T cells were able to persist in tumor-bearing hosts but declined in tumor-free animals. These results suggest that adoptive transfer of tumor-reactive TGF-beta-insensitive CD8+ T cells may warrant consideration for cancer therapy.

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.

Tubulocystic Carcinoma of the Kidney Clinicopathologic and Molecular Characterization

The nature of tubulocystic carcinoma, a rare renal tumor composed of tubular and cystic structures, is poorly understood. It has been suggested that it may represent a low-grade collecting duct carcinoma of the kidney despite the lack of sufficient molecular and pathologic evidence. The aim of this study was to examine the clinical and pathologic features of 13 cases of tubulocystic carcinoma of the kidney. Furthermore, using gene expression microarray analysis, we defined the molecular signature of this tumor by comparing it with other renal tumors in our previously established molecular profile database. Histologically, all 13 tumors were composed of closely packed tubules and cysts of varying sizes separated by fibrovascular septa. The epithelial lining cells of the tubules and cysts in this tumor were characterized by abundant eosinophilic cytoplasm with prominent nucleoli often showing a hobnail appearance. Clinically, one of the 13 cases showed metastasis to the pelvic lymph nodes. Five of the 13 cases coexisted with papillary renal cell carcinoma (RCC) (n=3) or papillary adenoma (n=2). In addition, the molecular profile of tubulocystic carcinoma was similar but not identical to those of papillary RCC by clustering analysis. Through comparative genomic microarray analysis, tubulocystic carcinoma showed gains of chromosome 17, but not chromosome 7, whereas most papillary RCCs showed chromosomal gains in both 7 and 17 (trisomies). Therefore, based on its unique pathologic features and molecular signature as well as its biologic behavior to develop metastasis either by itself or in association with papillary RCC, tubulocystic carcinoma of the kidney should be recognized as a distinct subtype of RCC and be distinguished from other malignant and benign cystic lesions of the kidney.