The multiple roles of LDH in cancer.

High serum lactate dehydrogenase (LDH) levels are typically associated with a poor prognosis in many cancer types. Even the most effective drugs, which have radically improved outcomes in patients with melanoma over the past decade, provide only marginal benefit to those with high serum LDH levels. When viewed separately from the oncological, biochemical, biological and immunological perspectives, serum LDH is often interpreted in very different ways. Oncologists usually see high serum LDH only as a robust biomarker of a poor prognosis, and biochemists are aware of the complexity of the various LDH isoforms and of their key roles in cancer metabolism, whereas LDH is typically considered to be oncogenic and/or immunosuppressive by cancer biologists and immunologists. Integrating these various viewpoints shows that the regulation of the five LDH isoforms, and their enzymatic and non-enzymatic functions is closely related to key oncological processes. In this Review, we highlight that serum LDH is far more than a simple indicator of tumour burden; it is a complex biomarker associated with the activation of several oncogenic signalling pathways as well as with the metabolic activity, invasiveness and immunogenicity of many tumours, and constitutes an extremely attractive target for cancer therapy.

15-Hydroxyprostaglandin-dehydrogenase is involved in anti-proliferative effect of non-steroidal anti-inflammatory drugs COX-1 inhibitors on a human medullary thyroid carcinoma cell line.

Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit prostaglandin (PG) synthesis enzymes, the cyclooxygenases (COX-1 and 2). It is suggested that these enzymes are not their only targets. We reported that in tumoral TT cell, indomethacin, in vivo and in vitro, decreases proliferation and increases activity of 15-hydroxyprostaglandin-dehydrogenase (15-PGDH), the PG catabolism key enzyme. Here, we show that the COX-1 inhibitors, selective or not, and sulindac sulfone, a non-COX inhibitor, increased 15-PGDH activity and reduced PGE2 levels. This increase was negatively correlated to the decrease in cell proliferation and suggested that 15-PGDH could be implicated in NSAIDs anti-proliferative effect. Indeed, the silencing of 15-PGDH expression by RNA interference using 15-PGDH specific siRNA enhanced TT cell proliferation and abolished the anti-proliferative effect of a representative non-selective inhibitor, ibuprofen. Moreover, a specific inhibitor of 15-PGDH activity, CAY 10397, completely reversed the effect of ibuprofen on proliferation. Consequently our results demonstrate that, at least in TT cells, 15-PGDH is implicated in proliferation and could be a target for COX-1 inhibitors specific or not. NSAIDs defined by their COX inhibition should also be defined by their effect on 15-PGDH.

Tumor growth inhibition by indomethacin in a mouse model of human medullary thyroid cancer: implication of cyclooxygenases and 15-hydroxyprostaglandin dehydrogenase.

Medullary thyroid cancer (MTC) is a C cell neoplasm-secreting calcitonin. Surgery remains the only treatment as the primary tumor and metastases resist radio- and chemotherapies. MTC produces high amounts of prostaglandins (PGs). Nonsteroidal antiinflammatory drugs have an antitumoral effect, generally related to the decrease of PG levels. We assessed the therapeutic potential of indomethacin in a model of human (TT cells) tumors in nude mice. Indomethacin (1.5 or 2.0 mg/kg body weight.d for 7 wk) inhibited tumor volume by 49 or 77%, respectively, and decreased the plasma level of CT. Although the terminal deoxynucleotidyltransferase-mediated deoxyuridine triphosphate nick end labeling method revealed few apoptotic nuclei, the number of proliferating cells was significantly decreased (Ki-67 antigen study). Immunological effector recruitment and vascular network was not modified by treatment. The inducible synthesis enzyme, cyclooxygenase-2 (COX-2), was revealed only in infiltrating cells, both in treated and control tumors. The expression of the constitutive synthesis enzyme COX-1 was diminished, and the expression of 15-prostaglandin dehydrogenase, the key enzyme catabolizing PGs, was increased in treated tumors. Thus, our results demonstrated the potential of indomethacin, inhibitor of COX-1 and COX-2, to prevent MTC growth. The synthesis enzyme, COX-1, and the catabolism enzyme 15-prostaglandin dehydrogenase, could be involved in MTC development.

Chk1 as a new therapeutic target in triple-negative breast cancer.

OBJECTIVES: Bioinformatics analyses of pathways and genes differentially expressed between malignant and benign lesions could allow discovering new therapeutic targets. Here, we identified Checkpoint kinase 1 (Chk1) as a potent therapeutic target in triple-negative breast cancer (TNBC). MATERIALS AND METHODS: Differential gene expression between TNBC, other malignant and benign lesions was performed on two breast cancer datasets. Chk1 was targeted using RNA interference or chemical inhibitor in several TNBC cell lines. RESULTS: DNA repair pathway was identified as one mostly deregulated pathway in TNBC as compared to benign lesions. Chk1 was identified as candidate target among the 35 genes included in this pathway. Gene expression analysis revealed that Chk1 gene was significantly overexpressed in TNBC as compared to non-TNBC and benign lesions. Depletion of Chk1 protein expression induced a marked reduction of cell viability and led to mitotic catastrophe in TNBC cells. Chemical Chk1 inhibitor decreased survival in TNBC cells, and transcriptome analyze revealed a modulation of gene expression profile in response to Chk1 treatment. CONCLUSION: These findings suggest that Chk1 may represent a therapeutic target in TNBC, and provide a rationale to evaluate Chk1 inhibitors in breast cancer patients.

Development of synchronous VHL syndrome tumors reveals contingencies and constraints to tumor evolution.

BACKGROUND: Genomic analysis of multi-focal renal cell carcinomas from an individual with a germline VHL mutation offers a unique opportunity to study tumor evolution. RESULTS: We perform whole exome sequencing on four clear cell renal cell carcinomas removed from both kidneys of a patient with a germline VHL mutation. We report that tumors arising in this context are clonally independent and harbour distinct secondary events exemplified by loss of chromosome 3p, despite an identical genetic background and tissue microenvironment. We propose that divergent mutational and copy number anomalies are contingent upon the nature of 3p loss of heterozygosity occurring early in tumorigenesis. However, despite distinct 3p events, genomic, proteomic and immunohistochemical analyses reveal evidence for convergence upon the PI3K-AKT-mTOR signaling pathway. Four germline tumors in this young patient, and in a second, older patient with VHL syndrome demonstrate minimal intra-tumor heterogeneity and mutational burden, and evaluable tumors appear to follow a linear evolutionary route, compared to tumors from patients with sporadic clear cell renal cell carcinoma. CONCLUSIONS: In tumors developing from a germline VHL mutation, the evolutionary principles of contingency and convergence in tumor development are complementary. In this small set of patients with early stage VHL-associated tumors, there is reduced mutation burden and limited evidence of intra-tumor heterogeneity.

Cancer cell-autonomous contribution of type I interferon signaling to the efficacy of chemotherapy.

Some of the anti-neoplastic effects of anthracyclines in mice originate from the induction of innate and T cell-mediated anticancer immune responses. Here we demonstrate that anthracyclines stimulate the rapid production of type I interferons (IFNs) by malignant cells after activation of the endosomal pattern recognition receptor Toll-like receptor 3 (TLR3). By binding to IFN-α and IFN-ß receptors (IFNARs) on neoplastic cells, type I IFNs trigger autocrine and paracrine circuitries that result in the release of chemokine (C-X-C motif) ligand 10 (CXCL10). Tumors lacking Tlr3 or Ifnar failed to respond to chemotherapy unless type I IFN or Cxcl10, respectively, was artificially supplied. Moreover, a type I IFN-related signature predicted clinical responses to anthracycline-based chemotherapy in several independent cohorts of patients with breast carcinoma characterized by poor prognosis. Our data suggest that anthracycline-mediated immune responses mimic those induced by viral pathogens. We surmise that such 'viral mimicry' constitutes a hallmark of successful chemotherapy.

Retinoic acid receptor alpha amplifications and retinoic acid sensitivity in breast cancers.

BACKGROUND: Molecular segmentation of breast cancer allows identification of small groups of patients who present high sensitivity to targeted agents. A patient, with chemo- and trastuzumab-resistant HER2-overexpressing breast cancer, who presented concomitant acute promyelocytic leukemia, showed a response in her breast lesions to retinoic acid, arsenic, and aracytin. We therefore investigated whether RARA gene amplification could be associated with sensitivity to retinoic acid derivatives in breast cancers. MATERIALS AND METHODS: Array comparative genomic hybridization and gene expression arrays were used to characterize RARA amplifications and expression in 103 breast cancer samples. In vitro activity of ATRA was characterized in T47D, SKBR3, and BT474 cell lines. RESULTS: Retinoic acid receptor alpha was gained or amplified in 27% of HER2-positive and 13% of HER2-negative breast cancer samples. Retinoic acid receptor alpha can be coamplified with HER2. Retinoic acid receptor alpha copy number changes could be correlated with messenger RNA expression. All-trans-retinoic acid reduced cell viability of RARA-amplified, but not RARA-normal, cell lines through apoptosis. Gene expression arrays showed that ATRA-induced apoptosis in RARA-amplified cell lines was related to an increase in CASP1 and IRF1. CONCLUSION: The results of this study suggest that breast cancers exhibiting RARA amplifications could be sensitive to retinoic acid. A phase II trial will evaluate this hypothesis in the clinical setting.

Targeting the deregulated spliceosome core machinery in cancer cells triggers mTOR blockade and autophagy.

The spliceosome is a large ribonucleoprotein complex that guides pre-mRNA splicing in eukaryotic cells. Here, we determine whether the spliceosome could constitute an attractive therapeutic target in cancer. Analysis of gene expression arrays from lung, breast, and ovarian cancers datasets revealed that several genes encoding components of the core spliceosome composed of a heteroheptameric Sm complex were overexpressed in malignant disease as compared with benign lesions and could also define a subset of highly aggressive breast cancers. siRNA-mediated depletion of SmE (SNRPE) or SmD1 (SNRPD1) led to a marked reduction of cell viability in breast, lung, and melanoma cancer cell lines, whereas it had little effect on the survival of the nonmalignant MCF-10A breast epithelial cells. SNRPE or SNRPD1 depletion did not lead to apoptotic cell death but autophagy, another form of cell death. Indeed, induction of autophagy was revealed by cytoplasmic accumulation of autophagic vacuoles and by an increase in both LC3 (MAP1LC3A) protein conversion and the amount of acidic autophagic vacuoles. Knockdown of SNRPE dramatically decreased mTOR mRNA and protein levels and was accompanied by a deregulation of the mTOR pathway, which, in part, explains the SNRPE-dependent induction of autophagy. These findings provide a rational to develop new therapeutic agents targeting spliceosome core components in oncology.

Anti-tumoral effect of a celecoxib low dose on a model of human medullary thyroid cancer in nude mice.

BACKGROUND: Medullary thyroid carcinoma (MTC) is a C cell neoplasm secreting calcitonin (CT). Surgery remains the only treatment as MTC is resistant to radio- and chemotherapies. Anti-tumoral effects of nonsteroidal anti-inflammatory drugs have been observed in various cancers. Thus, we tested the anti-tumoral action of an nonsteroidal anti-inflammatory drug, celecoxib, on MTC development. METHODS: We studied the expression of prostaglandin (PG) metabolism enzymes in our in vitro (TT cells) and in vivo (TT tumors) models and in human MTCs by Western blot. We checked the effect of celecoxib on xenografted subcutaneous tumors in nude mice. Celecoxib was administrated in powder food during 9 weeks from day 1 after TT cell injection. At the end of the experiment plasma CT was measured by radioimmunoassay, the number of proliferating cells in tumor tissues was detected by Ki67 immunocytochemistry and apoptotic nuclei by caspase 3 ad Bcl-2 expression and terminal-deoxynucleotidyl-transferase-mediated deoxyuridine triphosphate nick end labeling (TUNEL) method. PGE(2) concentrations in TT cell medium were evaluated by an enzyme immunoassay kit. RESULTS: Our in vitro and in vivo models were validated: the status of PG metabolism enzymes was comparable in these models and in human MTCs. A very low dose of celecoxib, 120 ppm in food, inhibited tumor volume by 71% and reduced plasma CT level. Although no proapoptotic effect was detectable in tumors, a decrease of proliferating cells was revealed. The inducible PG synthesis enzyme, cyclooxygenase 2, was only detectable in rare stromal cells. The expression of the constitutive PG synthesis enzyme, cyclooxygenase 1, was diminished, while the level of the catabolism enzyme, 15-PG dehydrogenase, was decreased. In vitro, TT cells treated for 12 days with 25 muM celecoxib reproduced these changes, and PGE(2) secretion was not significantly modified by the treatment, in these conditions. CONCLUSION: Celecoxib has a good therapeutic potential for MTC to prevent metastasis growth, and its anti-tumoral effect is, at least in part, independent of PGE(2).

Medullary thyroid carcinoma and hormones.

Medullary thyroid carcinoma (MTC) is a neuroendocrine tumor. The identification of calcitonin as a specific and sensitive marker in 1968 determined a special interest of endocrinologists. Many hormones have been isolated in MTC tumors. Calcitonin, prostaglandins and somatostatin are of particular interest. Calcitonin is not only a marker, but is indicative of tumor size and prognosis. Moreover the presence of calcitonin receptors in MTC could have a role in the proliferation of this tumor. Somatostatin and the large use of somatostatin analogs in the treatment of neuroendocrine tumors raise the hope that these drugs could be effective in MTC patients. Unfortunately, the benefits of these treatments is not validated. More interestingly, nonsteroidal anti-inflammatory drugs could be of interest in this tumor by comparison of their use in colorectal polyps. By inhibiting Cox or inducing 15 PGDH enzymes, we have demonstrated in vitro its effectiveness. Thus, hormones in MTC are not only markers but probably mediate biological effects involved in tumor growth.