B. P. Mello

Gene expression of peripheral blood lymphocytes may discriminate patients with schizophrenia from controls

To identify a classifier in schizophrenia, blood gene expression profiling was applied to patients with schizophrenia under different treatments and to controls. Expression of six genes discriminated patients with sensitivity of 89.3% and specificity of 90%, supporting the use of peripheral blood as biological material for diagnosis in schizophrenia.

No-match ORESTES explored as tumor markers

Sequencing technologies and new bioinformatics tools have led to the complete sequencing of various genomes. However, information regarding the human transcriptome and its annotation is yet to be completed. The Human Cancer Genome Project, using ORESTES (open reading frame EST sequences) methodology, contributed to this objective by generating data from about 1.2 million expressed sequence tags. Approximately 30% of these sequences did not align to ESTs in the public databases and were considered no-match ORESTES. On the basis that a set of these ESTs could represent new transcripts, we constructed a cDNA microarray. This platform was used to hybridize against 12 different normal or tumor tissues. We identified 3421 transcribed regions not associated with annotated transcripts, representing 83.3% of the platform. The total number of differentially expressed sequences was 1007. Also, 28% of analyzed sequences could represent noncoding RNAs. Our data reinforces the knowledge of the human genome being pervasively transcribed, and point out molecular marker candidates for different cancers. To reinforce our data, we confirmed, by real-time PCR, the differential expression of three out of eight potentially tumor markers in prostate tissues. Lists of 1007 differentially expressed sequences, and the 291 potentially noncoding tumor markers were provided.

PRAME/EZH2-Mediated Regulation of TRAIL: A New Target for Cancer Therapy

The tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) exerts a cancer cell-specific pro-apoptotic activity. This property made the TRAIL associated pathway one of the most promising strategies aimed at inducing tumor-selective death. In fact, several approaches have been considered to explore this pathway for cancer therapy, such as recombinant TRAIL, agonist antibodies for TRAIL receptors, and adenoviral TRAIL. However, all of these approaches have certain disadvantages that limit their clinical use. Our recent discovery that the complex PRAME/EZH2 is able to repress TRAIL expression, in a cancer-specific manner, suggests an alternative approach for combined cancer therapy. A genetic or pharmacological inhibition of TRAIL repressors in cancer cells could restore endogenous TRAIL expression, thereby overcoming some of the limitations of and/or cooperating with previous approaches.

Regulation of TRAIL expression by PRAME and EZH2 as potential therapeutic target against solid tumors

Background TRAIL, a member of the TNF ligand family, was shown to selectively kill cancer cells and, therefore, to participate in the cell-mediated immunity against tumors. However, TRAIL is down-regulated in a variety of cancers. Furthermore, PRAME (preferentially expressed antigen of melanoma) is frequently over expressed in a wide variety of malignant diseases. It was shown that PRAME, in a complex with a member of the polycomb group, EZH2, can function as a transcriptional repressor of retinoic acid receptor. Interestingly, TRAIL expression can be positively regulated by retinoic acid. Previous studies performed by us revealed that TRAIL is down-regulated and PRAME is up-regulated during development of chronic myeloid leukemia (CML) and that their normal levels are restored after complete cytogenetic remission (CCR). There was a significant, negative correlation between the expression of PRAME and TRAIL in CML patients. Over expression of BCR-ABL in the acute promyelocytic leukemia cell line HL-60 increased the levels of PRAME and decreased the levels of TRAIL. Knocking-down of either PRAME or EZH2 in K562 CML cell line resulted in TRAIL up-regulation.

Abstract B86: Epigenetic regulation of TRAIL mediated by PRAME/EZH2 in cancer.

TRAIL, a member of the TNF ligand family, was shown to selectively kill oncogenically transformed cells and, therefore, to participate in the cell-mediated immunity against tumors. However, TRAIL is down-regulated in a variety of tumor-bearing patients. On the other hand, PRAME (preferentially expressed antigen of melanoma) is frequently overexpressed in a wide variety of malignant diseases. It was shown that PRAME can function as a repressor of retinoic acid receptor and this transcriptional repression depends on the formation of a complex with a member of the polycomb group, EZH2 (enhancer of zeste homolog 2). Interestingly, TRAIL expression can be positively regulated by retinoic acid. Data from our lab revealed that TRAIL is down-regulated and PRAME is up-regulated during the development of chronic myeloid leukemia (CML) and that their normal levels are restored after complete cytogenetic remission (CCR). Furthermore, there was a significant, negative correlation between the expression of PRAME and TRAIL in CML patients. Overexpression of BCR-ABL in the acute promyelocytic leukemia cell line HL-60 increased the levels of PRAME and decreased the levels of TRAIL. Knocking-down of either PRAME or EZH2 in K562 CML cell line resulted in a dramatic up-regulation of TRAIL. We concluded that PRAME up-regulation by BCR-ABL plays an important role in CML pathogenesis by repressing retinoic acid signaling pathway and, consequently, down-regulating TRAIL expression, a potent anti-cancer agent as an inducer of the extrinsic pathway of apoptosis. On the basis of these results, we performed bioinformatics analysis, using the Oncomine Research platform, for PRAME and TRAIL expression on solid tumors. We found several works in which PRAME and TRAIL expressions were negatively correlated. In particular, PRAME was up-regulated while TRAIL was down-regulated in kidney, lung, prostate and sarcoma compared to normal tissues. These expression patterns of PRAME and TRAIL were confirmed by real-time PCR in tumor cell lines of prostate, breast, colon and pharynx. At this moment, we are expanding the validation of bioinformatics data in a larger number of tumor cell lines as well as in tumor and normal tissues from patients with different forms of cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr B86.