nutlin-3a and Endometrial-Neoplasms

L1CAM promotes cell motility, invasion and metastasis formation in various human cancers and can be considered as a driver of tumor progression. Knowledge about genetic processes leading to the presence of L1CAM in cancers is of considerable importance. Experimentally, L1CAM expression can be achieved by various means. Over-expression of the transcription factor SLUG or treatment of cells with TGF-β1 can induce or augment L1CAM levels in cancer cells. Likewise, hypomethylation of the L1CAM promoter on the X chromosome correlates with L1CAM expression. However, presently no mechanisms that might control transcriptional activity are known. Here we have identified miR-34a as a suppressor of L1CAM. We observed that L1CAM positive endometrial carcinoma (EC) cell lines HEC1B and SPAC1L lost L1CAM protein and mRNA by treatment with demethylating agents or knock-down of the DNA-methyltransferase-1 (DNMT1). Concomitantly, several miRNAs were up-regulated. Using miRNA profiling, luciferase reporter assays and mutagenesis, we identified miR-34a as a putative binder to the L1CAM-3'UTR. Over-expression of miR-34a in HEC1B cells blocked L1CAM expression and inhibited cell migration. In ECC1 cells (wildtype p53) the activation of p53 caused miR-34a up-regulation and loss of L1CAM expression that was miR-34a dependent. We observed an inverse correlation between L1CAM and miR-34a levels in EC cell lines. In primary tumor sections areas expressing high amounts of L1CAM had less miR-34a expression than those with low L1CAM levels. Our data suggest that miR-34a can regulate L1CAM expression by targeting L1CAM mRNA for degradation. These findings shed new light on the complex regulation of L1CAM in human tumors.

Topics: 3' Untranslated Regions; Azacitidine; Base Sequence; Cell Growth Processes; Cell Line, Tumor; Cell Movement; Endometrial Neoplasms; Female; Humans; Imidazoles; MicroRNAs; Molecular Sequence Data; Neural Cell Adhesion Molecule L1; Piperazines; Transcription Factors; Transcriptional Activation; Transfection

Ovarian cancer (OVCa) is the leading cause of death from gynecological malignancies. Although treatment for advanced OVCa has improved with the introduction of taxane-platinum chemotherapy, the majority of patients will develop resistance to the treatment, leading to poor prognosis. One of the causes of chemoresistance is the reduced ability to undergo apoptosis. Cisplatin is a genotoxic drug that leads cells to apoptosis through the activation of the p53 pathway. Defective signaling in this pathway compromises p53 function, and thus cisplatin does not induce apoptosis. A new group of nongenotoxic small molecules called Nutlins have been developed to inhibit p53-Mdm2 binding, inducing apoptosis in chemoresistant tumors through the activation of the p53 pathway. The wild-type p53 cisplatin-resistant ovarian cancer cell-line A2780cis was used to test the effect of Nutlin-3a (Nut3a) on apoptosis response. The results showed that Nut3a synergized with cisplatin, inducing cell-cycle arrest in G2/M and potentiating apoptotic cell death. Increased apoptosis was also induced in wild-type TP53 primary OVCa cultures by double cisplatin-Nut3a treatment. In conclusion, Nut3a appears to sensitize chemoresistant OVCa cells to cisplatin, inducing apoptosis. As increased response was generalized in primary tumors, this cisplatin-Nut3a combination could be useful for the treatment of patients harboring wild-type TP53 who do not respond to standard chemotherapy.

Topics: Adenocarcinoma, Mucinous; Antineoplastic Agents; Apoptosis; Blotting, Western; Cell Cycle; Cell Proliferation; Cisplatin; Cystadenocarcinoma, Serous; Drug Resistance, Neoplasm; Drug Synergism; Endometrial Neoplasms; Female; Flow Cytometry; Humans; Imidazoles; Inhibitor of Apoptosis Proteins; Neoplasm Grading; Ovarian Neoplasms; Piperazines; Proto-Oncogene Proteins c-mdm2; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; RNA, Small Interfering; Survivin; Tumor Cells, Cultured; Tumor Suppressor Protein p53