Dominant-negative activity of a Brca1 truncation mutant: Effects on proliferation, tumorigenicity in vivo, and chemosensitivity in a mouse ovarian cancer cell line

Sylvain, Valerie; Lafarge, Stéphane; Bignon, Yves‐Jean

doi:10.3892/ijo.20.4.845

Cited by 39 publications

(38 citation statements)

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“…In this cell system, the molecular mechanism of resistance to microtubuleinterfering agents was correlated to transcriptional changes in genes involved in the c-Jun NH(2)-terminal kinase (JNK) pathway. More recently, it has been reported that the expression of a truncated BRCA1 mutant with a dominant-negative activity modifies chemosensitivity in a mouse ovarian cancer cell line (Sylvain et al, 2002). Taken together, these findings suggest that changes in the sensitivity to antitumor agents could indeed be a part of the phenotype of breast carcinomas arising in the hereditary setting and could be of relevance in the treatment of these tumours.…”

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confidence: 55%

BRCA1 expression modulates chemosensitivity of BRCA1-defective HCC1937 human breast cancer cells

et al. 2003

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Germline mutations of the tumour suppressor gene BRCA1 are involved in the predisposition and development of breast cancer and account for 20 -45% of all hereditary cases. There is an increasing evidence that these tumours are characterised by a specific phenotype and pattern of gene expression. We have hypothesised that differences in chemosensitivity might parallel molecular heterogeneity of hereditary and sporadic breast tumours. To this end, we have investigated the chemosensitivity of the BRCA1-defective HCC1937 breast cancer cell line, and the BRCA1-competent MCF-7 (hormone-sensitive) and MDA-MB231 (hormoneinsensitive) breast cancer cell lines using the MTT assay. The 50% inhibitory concentration (IC 50 ) for the individual compounds were derived by interpolate plot analysis of the logarithmic scalar concentration curve after a 48 h exposure. HCC1937 cells were significantly (Po0.005) more sensitive to cisplatin (CDDP) (IC 50 : 30-40 mM) compared with MCF-7 (IC 50 : 60-70 mM) and MDA-MB231 (IC 50 : 90 -100 mM) cells. On the other hand, BRCA1-defective breast cancer cells were significantly less sensitive to doxorubicin (Dox) (IC 50 : 45-50 mM) compared with MCF-7 (IC 50 : 1-5 mM) and MDA-MB231 (IC 50 : 5-10 mM) (Po0.02), as well as to paclitaxel (Tax) (IC 50 : 42 mM for HCC1937, 0.1 -0.2 mM for MCF-7 and 0.01 -0.02 mM for MDA-MB231) (Po0.001). Full-length BRCA1 cDNA transfection of BRCA1-defective HCC1937 cells led to the reconstituted expression of BRCA1 protein in HCC1937/ WT BRCA1-derived cell clone, but did not reduce tumour cell growth in soft agar. BRCA1 reconstitution reverted the hypersensitivity to CDDP (Po0.02), and restored the sensitivity to Dox (Po0.05) and Tax (Po0.001), compared with parental HCC1937 cells. Taken together, our findings suggest a specific chemosensitivity profile of BRCA1-defective cells in vitro, which is dependent on BRCA1 protein expression, and suggest prospective preclinical and clinical investigation for the development of tailored therapeutical approaches in this setting.

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confidence: 55%

BRCA1 expression modulates chemosensitivity of BRCA1-defective HCC1937 human breast cancer cells

et al. 2003

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“…Several in vitro murine ovarian cancer models are also in agreement. First, overexpression of a BRCA1 dominant negative mutant in ID8 murine ovarian cancer cells correlates with increased sensitivity to cisplatin (24). Second, BRCA1-deficient murine ovarian surface epithelial cells were more sensitive to cisplatin-induced cell death when compared with corresponding BRCA1 wild-type cells (33).…”

Section: Discussionmentioning

confidence: 99%

“…However, in agreement with in vitro breast cancer cell line models, it has been shown that antisense inhibition of BRCA1 in cisplatin-resistant SKOV3 ovarian cancer cells dramatically sensitized these cells by disruption of BRCA1-dependent DNA repair (23). Similarly, overexpression of BRCA1 in ID8 murine ovarian cancer cells reduced sensitivity to cisplatin and other DNA-damaging agents (24). Furthermore, transfection of BRCA1 into the BRCA1-mutated SNU251 ovarian cancer cell line increased resistance to ionizing radiation (25).…”

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confidence: 99%

BRCA1 mRNA Expression Levels Predict for Overall Survival in Ovarian Cancer after Chemotherapy

Quinn

James

Stewart

et al. 2007

Clinical Cancer Research

200

153

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Purpose:We investigated whether BRCA1mRNA expression levels may represent a biomarker of survival in sporadic epithelial ovarian cancer following chemotherapy treatment. Experimental Design: The effect of loss of BRCA1 expression on chemotherapy response in ovarian cancer was measured in vitro using dose inhibition assays and AnnexinV flow cytometry. Univariate and multivariate analyses were done to evaluate the relationship between BRCA1 mRNA expression levels and survival after chemotherapy treatment in 70 fresh frozen ovarian tumors. Results: We show that inhibition of endogenous BRCA1 expression in ovarian cancer cell lines results in increased sensitivity to platinum therapy and decreased sensitivity to antimicrotubule agents. In addition, we show that patients with low/intermediate levels of BRCA1 mRNA have a significantly improved overall survival following treatment with platinum-based chemotherapy in comparison with patients with high levels of BRCA1mRNA (57.2 versus18.2 months; P = 0.0017; hazard ratio, 2.9). Furthermore, overall median survival for higher-BRCA1-expressing patients was found to increase following taxane-containing chemotherapy (23.0 versus 18.2 months; P = 0.12; hazard ratio, 0.53). Conclusions: We provide evidence to support a role for BRCA1 mRNA expression as a predictive marker of survival in sporadic epithelial ovarian cancer.The BRCA1 tumor suppressor gene is associated with susceptibility to both hereditary breast and ovarian cancer (1,2). Approximately 5% to 15% of ovarian cancers are inherited and BRCA1 germ-line mutations account for 90% of these cases conferring a cumulative lifetime risk of 54% compared with 1.8% within the general population (3, 4). Although somatic mutations of BRCA1 are uncommon in sporadic ovarian tumors (5), down-regulation of BRCA1 has been reported in >72% of high-grade sporadic ovarian cancers, suggesting that BRCA1 may also play a major role in the development of sporadic epithelial ovarian cancer (6, 7). Epigenetic inactivation of BRCA1 is at least partially due to hypermethylation of the BRCA1 promoter, which has been observed in up to 15% of cases (8,9).Several preclinical breast cancer studies have indicated that BRCA1 is an important determinant of response to both DNAdamaging and taxane-based chemotherapy. Evidence that BRCA1 deficiency, whether through inherited mutation or epigenetic down-regulation, confers marked sensitivity to DNAdamaging agents is derived from numerous in vitro studies (10 -15). Furthermore, several retrospective breast cancer clinical studies are in agreement with these preclinical findings. It has been shown that BRCA1 mutation carriers gain a significant survival advantage from DNA damage -based chemotherapy compared with non -mutation carriers (16,17). In addition, reduced BRCA1 protein expression in sporadic epithelial ovarian cancer was found to correlate with improved survival (18). Finally, a retrospective analysis of BRCA1 mRNA levels in a cohort of sporadic lung tumors showed that low-BRCA1-expressing ...

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“…Thus far, most of the studies have shown the existence of mutant proteins at the DNA or mRNA level (34,37). Some studies suggested the existence of mutant proteins by in vitro overexpression experiments, but the constructs used in the previous studies had PTCs in specific positions of the C-terminal region, which represents nonsense mutations (38)(39)(40). In most cancers, insertion/deletion mutations usually lead to frameshift mutations that are much more frequent and deleterious than nonsense mutations.…”

Section: Discussionmentioning

confidence: 99%

“…Because we confirmed that mRNAs derived from mutated genes were intact in the cytoplasm, the NMD-irrelevant mRNA model is essential to determine if truncated mutant proteins with neopeptides are expressed in tumors. Previously, several studies have attempted to detect truncated mutant proteins derived from PTC-carrying mRNAs and clarify the roles of these mutant proteins in diseases such as cancers and genetic diseases (13,(34)(35)(36)(37)(38)(39). Thus far, most of the studies have shown the existence of mutant proteins at the DNA or mRNA level (34,37).…”

Section: Discussionmentioning

confidence: 99%

Identification and Selective Degradation of Neopeptide-Containing Truncated Mutant Proteins in the Tumors with High Microsatellite Instability

Kim

Park

et al. 2013

Clinical Cancer Research

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Purpose: Frameshift mutations in coding mononucleotide repeats (cMNR) are common in tumors with high microsatellite instability (MSI-H). These mutations generate mRNAs containing abnormal coding sequences and premature termination codons (PTC). Normally, mRNAs containing PTCs are degraded by nonsense-mediated mRNA decay (NMD). However, mRNAs containing PTCs located in the last exon are not subject to degradation by NMD (NMD-irrelevant). This study aimed to discover whether genes with frameshift mutations in the last exon generate truncated mutant proteins.Experimental Design: We identified 66 genes containing cMNRs in the last exon by bioinformatic analysis. We found frequent insertion/deletion mutations in the cMNRs of 29 genes in 10 MSI-H cancer cell lines and in the cMNRs of 3 genes in 19 MSI-H cancer tissues. We selected 7 genes (TTK, TCF7L2, MARCKS, ASTE1, INO80E, CYHR1, and EBPL) for mutant mRNA expression analysis and 3 genes (TTK, TCF7L2, and MARCKS) for mutant protein expression analysis.Results: The PTC-containing NMD-irrelevant mRNAs from mutated genes were not degraded. However, only faint amounts of endogenous mutant TTK and TCF7L2 were detected, and we failed to detect endogenous mutant MARCKS. By polysome analysis, we showed that mRNAs from genomic mutant MARCKS constructs are normally translated. After inhibiting 3 protein degradation pathways, we found that only inhibition of the proteasomal pathway facilitated the rescue of endogenous mutant TTK, TCF7L2, and MARCKS.Conclusions: Our findings indicate that cancer cells scavenge potentially harmful neopeptide-containing mutant proteins derived from NMD-irrelevant abnormal mRNAs via the ubiquitin-proteasome system, and these mutant proteins may be important substrates for tumor-specific antigens.

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Dominant-negative activity of a Brca1 truncation mutant: Effects on proliferation, tumorigenicity in vivo, and chemosensitivity in a mouse ovarian cancer cell line

Cited by 39 publications

References 0 publications

BRCA1 expression modulates chemosensitivity of BRCA1-defective HCC1937 human breast cancer cells

BRCA1 expression modulates chemosensitivity of BRCA1-defective HCC1937 human breast cancer cells

BRCA1 mRNA Expression Levels Predict for Overall Survival in Ovarian Cancer after Chemotherapy

Identification and Selective Degradation of Neopeptide-Containing Truncated Mutant Proteins in the Tumors with High Microsatellite Instability

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