Science et thérapie du cancer

PTB-associated Splicing Factor (PSF) is a multifunctional protein involved in transcription repression, premRNA processing, and DNA repair. Transcriptional repression by PSF is mediated by its interaction with nuclear hormone receptors. However, the physiological context of PSF in regard to nuclear receptor signaling is still unclear. In this review, our recent study identified PSF as a novel PPARγ-interacting protein and demonstrated that PSF is involved in several important regulatory steps of colon cancer cell proliferation. Recently, the aberrant expression of PSF in tumor cells has been implicated in resistance to drugs that are commonly used in cancer therapy. Therefore, it might be possible to develop and to optimize drugs that inhibit PSF and correct abnormal splicing, resulting in enhanced tumor cell migration, invasion, and proliferation. In this review, we summarize current understanding of the mechanisms underlying the PSF-PPARγ axis and its role in the control of colorectal carcinogenesis.

RP215 is a monoclonal antibody generated against a carbohydrate-associated epitope of glycoproteins designated as CA215, which consists mainly of immunoglobulin superfamily proteins expressed by cancer cells including antigen receptors such as immunoglobulins and T-cell receptors. Since RP215 was shown to induce apoptosis and inhibit tumor growth in nude mouse models, the effects of RP215 and antibodies against antigen receptors on the gene regulations of cultured OC-3-VGH ovarian and C-33A cervical cancer cells were investigated through semi-quantitative RT-PCR. For both cell lines, RP215 and anti-antigen receptors were found to regulate similarly and consistently a number of genes including NFκB-1, IgG, P21, Cyclin D1, ribosomal P1 and c-fos with only exceptions for EGFR and ribosomal P0. Among toll-like receptor genes (TLR-2, -3, -4, -6, -7 and -9), differential levels of gene expressions in different cancer cell lines were observed. RP215 and anti-antigen receptors were found to up-regulate TLR-2 and/or TLR-3, whereas those of TLR-4 and TLR-9 were down regulated for both cancer cells. Based on these preliminary observations, it can be proposed that apoptosis of the two cancer cell lines was induced similarly by RP215 and anti-antigen receptors through consistent regulations of the same groups of genes. The innate immunity of cancer cells can also be affected by any of these antibodies through unidirectional regulations of certain toll-like receptors. Excellent correlations were obtained (R2=0.90-0.94) in terms of gene regulation patterns affected by any of these binding ligands. Therefore, the anti-cancer therapy of RP215 Mab may be, in part related to the surface bound antigen receptors and/or toll-like receptors in the innate immunity system, all of which may be involved in the growth and survival of cancer cells.

Introduction: Endemic (Balkan) Nephropathy is a chronic renal disease mainly affecting rural populations in the valleys of the Danube. In the absence of renal replacement therapy, it leads to fatal kidney failure and is significantly associated with upper urothelial carcinoma. Bread poisoning with aristolochic acids is now widely accepted. The source of this toxic substance is considered to be Aristolochia clematitis, a perennial plant that invades farming fields. The poisoning with aristolochic acids was suggested when clinical and histopathological changes similar to those observed in the Balkan patients were reported in several cases of nephropathy in Belgian patients unintentionally exposed to aristolochic acids during a Chinese herbs diet. Those clinical and histopathological features were then reproduced in laboratory experimental models.

Methods: Using metabonomics, an emerging dynamic technique that allows an effective mapping of alterations in endogenous metabolites levels in biofluids and tissues, we evaluated early signs of renal toxicity from extra urine samples collected in a rat model of intoxication with aristolochic acids.

Results: Changes in urine composition were consistent with a proximal tubular damage, most likely initiated by a mitochondrial default and an inappropriate response to oxidative stress. The same metabonomic approach was applied to surplus of urine samples collected from Belgian and Croatian patients in clinical and epidemiological studies, respectively. It allowed a clear discrimination of the Belgian patients from a database of healthy volunteers. On the other hand, a trend to discrimination was noticed when comparing urine samples collected from individuals living in Croatian endemic regions as compared to Croatian non endemic villages. Finally, when included in the same analysis, both Belgian and Croatian patients displayed similar urine metabolic signatures, suggesting a common etiology of both diseases.

The combination of cytotoxic drugs with immunotherapy should be more effective than monotherapy alone since both therapeutic modalities may target different mechanisms. In addition, combination therapy may reduce adverse events associated with cytotoxic drugs. Eriobotrya japonica hydrophilic butanol-treated extract (EJWR) was found to modulate cytokines by enhancing IL-12, IFN-γ and TNF-α in vitro and in vivo and within tumor microenvironment. This was associated with enhancing survival time of mice bearing intra-peritoneal MCA fibrosarcoma (MCA FS). In the present work, we evaluated the combination of EJWR with doxorubicin (Dox) on MCA FS cytotoxicity using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction assay in the absence and presence of spleen cells or Natural Killer (NK) lymphocytes from tumor bearing mice. The results showed that Dox exhibited mild cytotoxicity to healthy spleen cells and EJWR reversed such cytotoxicity. In addition, increasing concentrations of Dox induced 40% (p<0.01) MCA FS cytotoxicity. This percent increased significantly to 60% at Dox 5 μM when co-cultured with NK cells from tumor bearing mice and increased further to 80% (p<0.01) when Dox was combined with EJWR. The latter increase in cytotoxicity was significantly (p<0.01) higher than each agent alone. This enhancement was associated with significant production of TNF-α and retaining IFN-γ levels from NK cells lysates. This concluded that the immunomodulator, EJWR, mediates NK activation and enhances Dox- induced MCA FS cytotoxicity.

Oral squamous cell carcinoma (OSCC) is an aggressive malignancy which shows a variable degree of malignant behavior. To identify molecular signatures and establish a new diagnostic model for oral malignancies, we have identified marker genes representing pre-malignant and malignant phenotypes of oral mucosal lesions. The expression of marker genes was examined by quantitative reverse transcription-PCR. Then, we created discriminatory predictor models using Fisher’s linear discriminant analysis and leave-one-out cross validation. These models were applicable for the diagnoses of pre-malignant leukoplakias (LPs), and of invasion status for advanced OSCCs.

The clinical course of various cancers is also influenced by host immune response. Our preliminary data using flow cytometric analysis demonstrate that the percentage of CD4+CD57+ T cells in peripheral blood lymphocyte was higher in the high grade OSCCs than that in the low grade ones. Furthermore, lipopolysaccharides (LPS)-induced ex-vivo production of Interferon (IFN)-γ from peripheral blood cells was highest in stage I patients and gradually decreased during the course of OSCC progression up to stage III. These decreased levels in the early stages were inversely correlated with tumor size.

In this review, we propose that the usage of the immunological status of OSCC patients combined with the molecular signatures of tumor tissues could provide valuable indices for diagnosis of oral malignancies.