Quercetin abrogates chemoresistance in melanoma cells by modulating ΔNp73

<p>Abstract</p> <p>Background</p> <p>The alkylating agent Dacarbazine (DTIC) has been used in the treatment of melanoma for decades, but when used as a monotherapy for cancer only moderate response rates are achieved. Recently, the clinical use of Temozolomide (TMZ) has become the more commonly used analog of DTIC-related oral agents because of its greater bioavailability and ability to cross the blood brain barrier. The response rates achieved by TMZ are also unsatisfactory, so there is great interest in identifying compounds that could be used in combination therapy. We have previously demonstrated that the bioflavonoid quercetin (Qct) promoted a p53-mediated response and sensitized melanoma to DTIC. Here we demonstrate that Qct also sensitizes cells to TMZ and propose a mechanism that involves the modulation of a truncated p53 family member, ΔNp73.</p> <p>Methods</p> <p>DB-1 melanoma (p53 wildtype), and SK Mel 28 (p53 mutant) cell lines were treated with TMZ (400 μM) for 48 hrs followed by Qct (75 μM) for 24 hrs. Cell death was determined by Annexin V-FITC staining and immunocytochemical analysis was carried out to determine protein translocation.</p> <p>Results</p> <p>After treatment with TMZ, DB-1 cells demonstrated increased phosphorylation of Ataxia telangiectasia mutated (ATM) and p53. However, the cells were resistant to TMZ-induced apoptosis and the resistance was associated with an increase in nuclear localization of ΔNp73. Qct treatment in combination with TMZ abolished drug insensitivity and caused a more than additive induction of apoptosis compared to either treatment alone. Treatment with Qct, caused redistribution of ΔNp73 into the cytoplasm and nucleus, which has been associated with increased p53 transcriptional activity. Knockdown of ΔNp73 restored PARP cleavage in the TMZ treated cells, confirming its anti-apoptotic role. The response to treatment was predominantly p53 mediated as the p53 mutant SK Mel 28 cells showed no significant enhancement of apoptosis.</p> <p>Conclusion</p> <p>This study demonstrates that Qct can sensitize cells to TMZ and that the mechanisms of sensitization involve modulation of p53 family members.</p

Protein-induced unwinding of DNA: measurement by gel electrophoresis of complexes with DNA minicircles. Application to restriction endonuclease EcoRI, catabolite gene activator protein and lac repressor.

An electrophoretic procedure for the measurement of the helix unwinding induced by a sequence-specific protein is described. The method, which was applied here to EcoR I, CAP and lac repressor, involved the migration of the complexes with positively and negatively supercoiled DNA minicircles carrying a single protein binding site. Mobility shifts of complexes relative to naked DNAs appeared to be a result of i) the unwinding; of ii) an increase in the molecular frictional coefficient, which led to a retardation; of iii) bending, in the particular case of CAP, which induced an acceleration; and of iv) looping, in the case of lac repressor, which also resulted in an acceleration. Under conditions where the migration of the naked topoisomers was V-like (topoisomer mobility showed the same linear increase with both negative and positive supercoilings; Zivanovic et al. (1986) J. Mol. Biol., 192, 645-660), the protein unwinding contribution to mobility was assumed to be identical to that experimentally observed in the case of a thermal unwinding: all negatively supercoiled topoisomers were retarded and all positively supercoiled topoisomers were accelerated to the same extent. In contrast, the mobility contribution of the frictional term, as well as those of bending and looping, appeared to vary strongly with the magnitude of the supercoiling, but only weakly with its polarity. As a consequence, these latter contributions may approximately cancel when one is measuring the difference between the shifts observed for two comigrating, negatively and positively supercoiled, topoisomers, allowing the unwinding to be calculated. While estimates obtained for EcoR I, 23 +/- 3 degrees, and CAP, about 29 degrees, were in good agreement with previous measurements using topoisomerase I, the value found for lac repressor, 13 to 16 degrees, was significantly smaller

C-erbB2 gene amplification, an independent prognostic indicator in node-positive and node-negative breast cancers

International audienc

Association of c-erbB2-gene amplification with poor prognosis in non-inflammatory breast carcinomas but not in carcinomas of the inflammatory type.

International audienceIt is now accepted that c-erbB2-gene amplification is correlated with poor clinical outcome for patients, mainly when axillary nodes are invaded. We have confirmed this result by multivariate analysis in 178 patients with non-inflammatory breast cancer followed up for a mean period of 6.8 years (SD, 1.6 years). In addition, we have shown that c-erbB2 amplification, found in 30 (17%) specimens, was associated with a high risk of multiple metastases developing simultaneously. In contrast, for the 67 patients with inflammatory breast carcinoma, the most aggressive type of breast carcinoma, the c-erbB2 amplification detected in 24 (36%) specimens was not found to be associated with a higher risk of death, suggesting that the c-erbB2 gene plays a different role in the progression of these 2 types of breast cancer. Furthermore, our data stress the importance of the methodological approach used to determine gene amplification. Although Southern blot hybridization is a tumour- and time-consuming method not easy to adopt in routine clinical practice, this method remains a reference quantitative method

LncRNA H19 interacted with miR‐130a‐3p and miR‐17‐5p to modify radio‐resistance and chemo‐sensitivity of cardiac carcinoma cells

Abstract The current investigation explored the synthetic contribution of lncRNA H19, miR‐130a‐3p, and miR‐17‐5p to radio‐resistance and chemo‐sensitivity of cardiac cancer cells. Totally 284 human cardiac cancer tissues were gathered, and they have been pathologically diagnosed. The cardiac cancer cells were isolated with utilization of the mechanic method. Moreover, cisplatin, adriamycin, mitomycin, and 5‐fluorouracil were designated as the chemotherapies, and single‐dose X‐rays were managed as the radiotherapy for cardiac cancer cells. We also performed luciferase reporter gene assay to verify the targeted relationship between H19 and miR‐130a‐3p, as well as between H19 and miR‐17‐5p. Finally, mice models were established to examine the functions of H19, miR‐130a‐3p, and miR‐17‐5p on the development of cardiac cancer. The study results indicated that H19, miR‐130a‐3p, and miR‐17‐5p expressions within cardiac cancer tissues were significantly beyond those within adjacent nontumor tissues (P < 0.05), and H19 expression was positively correlated with both miR‐130a‐3p (rs = 0.43) and miR‐17‐5p (rs = 0.49) expressions. The half maximal inhibitory concentrations (IC50) of cisplatin, adriamycin, mitomycin, and 5‐fluorouracil for cardiac cancer cells were, respectively, determined as 2.01 μg/mL, 8.35 μg/mL, 24.44 μg/mL, and 166.42 μg/mL. The overexpressed H19, miR‐130a‐3p, and miR‐17‐5p appeared to improve the survival rate and viability of cardiac cancer cells that were exposed to chemotherapies and X‐rays (all P < 0.05). It was also drawn from luciferase reporter gene assay that H19 could directly target miR‐130a‐3p and miR‐17‐5p, thereby modifying the sensitivity of cardiac cancer cells to drugs and X‐rays (P < 0.05). Finally, the mice models also produced larger tumor size and higher tumor weight, when H19, miR‐130a‐3p, or miR‐17‐5p expressions were up‐regulated within them (P < 0.05). In conclusion, H19 could act on miR‐130a‐3p or miR‐17‐5p to alter the radio‐ and chemo‐sensitivities of cardiac cancer cells, helping to improve the radio‐/chemotherapies for cardiac cancer

GALNT9 Gene Expression Is a Prognostic Marker in Neuroblastoma Patients

International audienceBACKGROUND: The enzymes encoded by the GALNT [UDP-N-acetyl-α-d-galactosamine:polypeptide N-acetylgalactosaminyltransferase (GALNAC-T)] gene family catalyze the first step of O-glycosylation. Little is known about the link between expression of the genes encoding GALNAC-T enzymes and tumor progression in neuroblastoma, a pediatric cancer that can be classified as either low or high risk. We assessed the expression of genes in the GALNT family in a large cohort of neuroblastoma patients and characterized members of this family that might be used as new prognostic markers. METHODS: Reverse-transcription PCR analysis of 14 GALNT genes with a panel of neuroblastoma cell lines identified the GALNT9 gene as playing a potential role in disease progression. We used the log-rank test and the multivariable Cox proportional hazards model with a cohort of 122 neuroblastoma patients to analyze the relationship between GALNT9 expression and overall survival or disease-free survival. RESULTS: In the high-risk neuroblastoma experimental model IGR-N-91, GALNT9 expression was present in neuroblasts derived from primary tumors but not in neuroblasts from metastatic bone marrow. Moreover, GALNT9 in neuroblastoma cell lines was expressed in substrate adherent (S)-type cell lines but not in neuronal (N)-type lines. In the tumor cohort, GALNT9 expression was associated with high overall survival, independent of the standard risk-stratification covariates. GALNT9 expression was significantly associated with disease-free survival for patients currently classified as at low risk (P < 0.0007). CONCLUSIONS: GALNT9 expression correlates with both improved overall survival in low- and high-risk groups and an improved clinical outcome (overall and disease-free survival) in low-risk patients. Thus, the GALNT9 expression may be a prognostic marker for personalized therapy