Laurent Daniel

In vivo pH in metabolic-defective Ras-transformed fibroblast tumors: key role of the monocarboxylate transporter, MCT4, for inducing an alkaline intracellular pH.

We present an investigation of tumor pH regulation, designed to support a new anticancer therapy concept that we had previously proposed. Our study uses a tumor model of ras‐transformed hamster fibroblasts, CCL39, xenografted in the thighs of nude mice. We demonstrate, for the first time, that genetic modifications of specific mechanisms of proton production and/or proton transport result in distinct, reproducible changes in intracellular and extracellular tumor pH that can be detected and quantified noninvasively in vivo, simultaneously with determinations of tumor energetic status and necrosis in the same experiment. The CCL39 variants used were deficient in the sodium/proton exchanger, NHE‐1, and/or in the monocarboxylate transporter, MCT4; further, variants were deficient in glycolysis or respiration. MCT4 expression markedly increased the gradient between intracellular and extracellular pH from 0.14 to 0.43 when compared to CCL39 wild‐type tumors not expressing MCT4. The other genetic modifications studied produced smaller but significant increases in intracellular and decreases in extracellular pH. In general, increased pH gradients were paralleled by increased tumor growth performance and diminished necrotic regions, and 50% of the CCL39 variant expressing neither MCT4 nor NHE‐1, but possessing full genetic capacity for glycolysis and oxidative phosphorylation, underwent regression before reaching a 1‐cm diameter. Except for CCL39 wild‐type tumors, no significant HIF‐1α expression was detected. Our in vivo results support a multipronged approach to tumor treatment based on minimizing intracellular pH by targeting several proton production and proton transport processes, among which the very efficient MCT4 proton/lactate co‐transport deserves particular attention.

Expression of cell adhesion molecules in normal nerves, chronic axonal neuropathies and Schwann cell tumors

Cell adhesion molecules (CAMs) play a role in the normal development and regeneration of tissues as well as in the biological behaviour of tumors. We studied the immunohistochemical expression of various CAMs, such as neural cell adhesion molecule (NCAM), its polysialylated isoform (PSA-NCAM), epithelial (E-) cadherin, and beta1 integrins (alpha2beta1, alpha5beta1, alpha6beta1) in a series of frozen specimens of 10 normal nerves, 5 axonal neuropathies, 26 benign Schwannomas and 2 malignant peripheral nerve sheath tumors (MNST). NCAM was expressed by non-myelinating Schwann cells from normal nerves and overexpressed by Schwann cells from patients with chronic axonal neuropathies and Schwannomas. The expression was lower in MNST. Expression of PSA-NCAM was heterogeneously displayed by Schwann cells from the various tissues studied. Anti E-cadherin immunoreactivity was present in myelin sheath in normal nerves and axonopathies. It was expressed in some Schwannomas especially in vestibular Schwannomas. Integrins VLA alpha2 and VLA alpha6 were widely expressed by Schwann cells from normal nerves, axonal neuropathies and Schwannomas but their expression was low in MNST. VLA alpha5 was not expressed by Schwann cells from normal nerve and Schwannomas but present in chronic axonal neuropathies and MNST. In addition VLA alpha6 was strongly expressed by perineurial cells. These data show that CAMs have a characteristic pattern of expression in normal nerve. Also, some CAMs are always expressed by Schwann cells but the expression of others differs in normal nerves versus axonopathies or tumors, suggesting a role of the microcellular environment in the regulation of CAM expression. Schwannomas have different pattern of expression than MNST.

The PEN5 Epitope Identifies an Oligodendrocyte Precursor Cell Population and Pilocytic Astrocytomas

PEN5 is a sulfated polylactosamine carbohydrate epitope first described in a subpopulation of mature natural killer cells. Here we report that it is also expressed in a developmentally regulated fashion in human and rat central nervous systems and that its protein carrier is P-selectin glycoprotein ligand-1 (PSGL-1), a ligand for selectins. In rat neural primary cultures, PEN5 is transiently and selectively expressed by oligodendrocyte precursor cells and marks the transition from proliferative to postmitotic stages. In concordance, in human central nervous system tumors, PEN5 is observed in a subset of oligodendrogliomas and in all pilocytic astrocytomas, a class of tumor of uncertain histogenesis. These data suggest that PEN5-PSGL-1 plays a role in the differentiation of oligodendrocytes and that pilocytic astrocytomas are likely to result from a dysregulation occurring in oligodendrocyte precursor cells at the crucial stage of exit from the cell cycle.

Expression and role of adrenomedullin in renal tumors and value of its mRNA levels as prognostic factor in clear-cell renal carcinoma

Antiangiogenic therapies are used for advanced clear‐cell renal carcinomas (cRCC), but without curative possibilities, underlining the need for new therapeutic targets. Adrenomedullin (AM), a multifunctional peptide, is highly expressed in several tumors and plays an important role in angiogenesis and tumor growth through its receptors: calcitonin receptor‐like receptor/receptor activity‐modifying protein 2 and 3 (CLR/RAMP2 and CLR/RAMP3). In this study, real‐time quantitative reverse‐transcription‐PCR showed AM mRNA levels were higher in cRCC and in chromophobe renal carcinomas (chRCC) than in normal renal tissue. Interestingly, AM mRNA expression in cRCC correlated strongly with VEGF‐A mRNA expression. Immunohistochemically, AM, CLR and RAMP2 were localized in the carcinomatous epithelial compartment of cRCC. Interestingly, RAMP3 immunostaining was found only in the inflammatory cells that infiltrated tumors, suggesting a cross talk between tumor cells and the microenvironment. We also observed that cRCC cells BIZ and 786‐O expressed and secreted AM into the culture medium. In vitro, exogenous AM treatment stimulated cell proliferation, migration and invasion, indicating the cell can respond to AM. The action of AM was specific and was mediated by the CLR/RAMP2 and CLR/RAMP3 receptors. Clinical data showed the prognostic value of AM. High AM mRNA levels were associated with an increased risk of relapse after curative nephrectomy for cRCC. These findings highlight the implication of the AM pathway in the metastatic process and the prognostic relevance of AM in cRCC and point to a potential new therapeutic target.

Adrenomedullin as a therapeutic target in angiogenesis

Importance of the field: Hypoxia, a frequent characteristic in the microenvironment of solid tumors, leads to adrenomedullin (AM) upregulation through the hypoxia inducible factor-1 pathway, explaining its high expression in a variety of malignant tissues. AM is believed to play an important role in tumor progression and angiogenesis in many cancers. Therefore, it could become a new therapeutic target. Areas covered in this review: We performed a review of the literature based on published data to highlight AMs critical roles in tumor cell growth and cancer invasiveness, and its involvement in tumor angiogenesis through promotion of recruitment of hematopoietic progenitors, vascular morphogenesis, and blood vessel stabilization and maturation. Inhibition of AM has antitumoral effects linked to antiangiogenic effects but in some cases also to direct antiproliferative activity on cancer cells. Several studies demonstrated that systemic inhibition of AM receptors was well tolerated in murine models. What the reader will gain: The goal of this review is to inform readers about the role of AM in tumor angiogenesis and cancer progression and, therefore, about its possible place as a new therapeutic target. Take home message: Taken together, these data support targeting the AM pathway as a new potential therapy in cancer, complementary to other existing treatments.

Kinetics of postbiopsy levels of serum free prostate-specific antigen and percent free prostate-specific antigen

OBJECTIVES We evaluated the effects of transrectal ultrasound-guided biopsy of the prostate on serum total and free prostate-specific antigen (PSA) and the free/total PSA ratio and factors affecting variations in PSA levels. METHODS Serum total and free PSA levels and the free/total PSA ratio were determined in 48 men (mean age 66+/-7 years) before and 1 hour, 8 days, and 30 days after prostate biopsy. At least six cores were taken using a biopsy gun with an 18-gauge needle. The coefficient of variation of PSA was calculated as the postbiopsy/prebiopsy PSA ratio. Changes in PSA levels and the coefficient of variation were studied. RESULTS Fifteen (31%) of 48 men had adenocarcinoma on biopsy. Total and free PSA values were significantly increased 1 hour and 8 days after biopsy, and both returned to baseline 30 days after biopsy. The free/total PSA ratio was significantly increased (55%) 1 hour after biopsy and significantly decreased (12%) 8 days after biopsy. Thirty days after biopsy, the median of the free/total PSA ratio (18%) was not significantly different from the prebiopsy ratio (16%). The median of the coefficient of variation of the free/total PSA ratio was 3, 0.7, and 1 at 1 hour, 8 days, and 30 days after biopsy, respectively. Age, prostate volume, number of cores, and digital rectal examination and histologic findings were not significantly associated with variation in percent free PSA. Variation in percent free PSA at day 8 was associated with prebiopsy total PSA value and the free/total PSA ratio. CONCLUSIONS Prostate biopsy dramatically alters the percent free PSA. The free/total PSA ratio was decreased 8 days after biopsy and returned to prebiopsy levels in 75% of patients at 1 month after biopsy. Measurement of free PSA levels and the free/total PSA ratio should not be done within 4 weeks of prostate biopsy.