André Fedier

Resistance to topoisomerase poisons due to loss of DNA mismatch repair

Sporadic breast carcinomas demonstrate microsatellite instability, reflecting the presence of DNA mismatch repair‐deficient cells, in about one fourth of cases at the time of diagnosis. Loss of DNA mismatch repair has been reported to result in resistance not only to cisplatin and alkylating agents but also to the topoisomerase II poison doxorubicin, suggesting an association between DNA mismatch repair and topoisomerase II poison‐induced cytotoxicity. Our study investigates the relationship between loss of MSH2 or MLH1 function and sensitivity to the topoisomerase I and II poisons, and to the taxanes, 2 classes of cytotoxic drugs commonly used in breast cancer. Two pairs of cell lines proficient and deficient in mismatch repair due to loss of either MSH2 or MLH1 function were used. Loss of either MSH2 or MLH1 function resulted in resistance to the topoisomerase II poisons doxorubicin, epirubicin and mitoxantrone, whereas only loss of MLH1 function was associated with low‐level resistance to the topoisomerase I poisons camptothecin and topotecan. In contrast, there was no resistance to docetaxel and paclitaxel. Our data support the hypothesis that both MSH2 and MLH1 are involved in topoisomerase II poison‐mediated cytotoxicity, whereas only MLH1 is involved in topoisomerase I poison‐mediated cytotoxicity. Since our study shows that loss of DNA mismatch repair does not result in resistance to the taxanes, these drugs can be recommended for use in breast cancer deficient in mismatch repair.

Romidepsin reduces histone deacetylase activity, induces acetylation of histones, inhibits proliferation, and activates apoptosis in immortalized epithelial endometriotic cells

Romidepsin inhibited HDAC activity, produced acetylation of the histone proteins, up-regulated p21, and down-regulated cyclins B1 and D1, resulting in proliferation inhibition and apoptosis activation in 11z immortalized epithelial endometriotic cells. Our findings provide evidence that endometriotic cells are sensitive to the epigenetic effects of romidepsin and suggest that endometriosis may be therapeutically targeted by romidepsin.

Expression of the G protein-coupled estrogen receptor (GPER) in endometriosis: a tissue microarray study

BackgroundThe G protein-coupled estrogen receptor (GPER) is thought to be involved in non-genomic estrogen responses as well as processes such as cell proliferation and migration. In this study, we analyzed GPER expression patterns from endometriosis samples and normal endometrial tissue samples and compared these expression profiles to those of the classical sex hormone receptors.MethodsA tissue microarray, which included 74 samples from different types of endometriosis (27 ovarian, 19 peritoneal and 28 deep-infiltrating) and 30 samples from normal endometrial tissue, was used to compare the expression levels of the GPER, estrogen receptor (ER)-alpha, ER-beta and progesterone receptor (PR). The immunoreactive score (IRS) was calculated separately for epithelium and stroma as the product of the staining intensity and the percentage of positive cells. The expression levels of the hormonal receptors were dichotomized into low (IRS < 6) and high (IRS > =6) expression groups.ResultsThe mean epithelial IRS (+/−standard deviation, range) of cytoplasmic GPER expression was 1.2 (+/−1.7, 0–4) in normal endometrium and 5.1 (+/−3.5, 0–12) in endometriosis (p < 0.001), of nuclear GPER 6.4 (+/−2.6, 0–12) and 6.8 (+/−2.9, 2–12; p = 0.71), of ER-alpha 10.6 (+/−2.4, 3–12) and 9.8 (+/−3.0, 2–12; p = 0.26), of ER-beta 2.4 (+/−2.2; 0–8) and 5.6 (+/−2.6; 0–10; p < 0.001), and of PR 11.5 (+/−1.7; 3–12) and 8.1 (+/−4.5; 0–12; p < 0.001), respectively. The mean stromal IRS of nuclear GPER expression was 7.7 (+/−3.0; 2–12) in endometrium and 10.8 (+/−1.7; 6–12) in endometriosis (p < 0.001), of ER-alpha 8.7 (+/−3.1; 2–12) and 10.6 (+/−2.4; 2–12; p = 0.001), of ER-beta 1.8 (+/−2.0; 0–8) and 5.4 (+/−2.5; 0–10; p < 0.001), and of PR 11.7 (+/−0.9; 8–12) and 10.9 (+/−2.0; 3–12; p = 0.044), respectively. Cytoplasmic GPER expression was not detectable in the stroma of endometrium and endometriosis. The observed frequency of high epithelial cytoplasmic GPER expression levels was 50% (n = 30/60) in the endometriosis and none (0/30) in the normal endometrium samples (p < 0.001). High epithelial cytoplasmic GPER expression levels were more frequent in endometriomas (14/20, 70%; p = 0.01), as compared to peritoneal (9/18, 50%) or deep-infiltrating endometriotic lesions (7/22, 31.8%). The frequency of high stromal nuclear GPER expression levels was 100% (n = 74/74) in endometriosis and 76.7% (n = 23/30) in normal endometrium (p < 0.001). The frequency of high epithelial nuclear GPER expression levels did not differ between endometriosis and normal endometrium.ConclusionsThe present data indicate a unique GPER expression pattern in endometriosis, especially in endometriomas as compared to the normal endometrium. The overexpression of GPER in endometriotic lesions suggests a potential role for GPER in the hormonal regulation of endometriosis, which should be taken into consideration for future hormonal treatment strategies.

p53-deficient cells display increased sensitivity to anthracyclines after loss of the catalytic subunit of the DNA-dependent protein kinase.

DNA-dependent protein kinase (DNA-PK) is involved in non-homologous end joining which repairs DNA double-strand breaks introduced by irradiation and radiomimetic agents. DNA-PK interacts with p53 but may also have p53-independent functions. The present study investigated whether disruption of the gene for the catalytic subunit DNA-PKcs affects chemosensitivity in p53-deficient cells. Drug sensitivity of DNA-PKcs(+/+)/p53(+/+), DNA-PKcs(+/+)/p53(-/-), DNA-PKcs(-/-)/p53(+/+), and DNA-PKcs(-/-)/p53(-/-) mouse lung-fibroblasts was determined by the MTT assay, the clonogenic assay, and trypan blue exclusion. Susceptibility to apoptosis was determined by DNA fragmentation (TUNEL) and by caspase-3 cleavage. We show that p53-deficient cells were 2 to 3-fold resistant to treatment with doxorubicin, epirubicin, cisplatin, and docetaxel as compared to wild-type cells. We further demonstrate that the additional loss of DNA-PKcs function in p53-deficient cells resulted in a 2-fold increase in sensitivity to doxorubicin and epirubicin as documented by the MTT assay, clonogenic assay, and trypan blue exclusion. Doxorubicin-induced hypersensitivity in these cells correlated with a transient G2/M checkpoint activation but did not seem to correlate with apoptosis. The data indicate that additional loss of DNA-PKcs in p53-deficient cells reverses anthracycline-resistance imposed by p53-deficiency, and that DNA-PKcs modulates p53-independent pathways responding to DNA damage induced by anthracyclines. They also indicate that processes other than apoptosis may contribute to the increased cytotoxicity to anthracyclines. DNA-PKcs may thus be a potential target for functional inhibition, which might increase the efficacy of some anti-tumour agents in the treatment of cancers mutated in the p53 gene.

Cordycepin (3′-Deoxyadenosine), an Inhibitor of mRNA Polyadenylation, Suppresses Proliferation and Activates Apoptosis in Human Epithelial Endometriotic Cells in vitro

Background/Aims: Endometriosis is a benign but chronic disorder associated with pelvic pain and infertility. Enhanced proliferation and reduced apoptosis susceptibility are characteristics of endometriosis. Cordycepin is a poly(A) polymerase inhibitor. It induces shortening of poly(A) tails, leading to destabilization of mRNAs and finally to proliferation inhibition and cell death in normal and tumor cells. The potential of cordycepin to block proliferation and survival of 11z human immortalized epithelial endometriotic cells was determined. Methods: 11z cell cultures were treated with cordycepin. Cordycepin-induced inhibition of proliferation and alterations in protein expression and protein phosphorylation were determined by the methyl thiazolyl tetrazolium assay and immunoblot analysis, respectively. Results: Cordycepin induced the rapid and significant upregulation of the cell cycle progression inhibitor p21 and the downregulation of the cell cycle progression promoter cyclin D1, finally leading to the inhibition of the proliferation of 11z human epithelial endometriotic cells. Cordycepin reduced the phosphorylation of the p38 mitogen-activated protein kinase and the retinoblastoma protein. It also activated caspase-dependent, intrinsic apoptosis, as documented by the proteolytic cleavage of the caspase-9, caspase-3 and the poly(ADP ribose) polymerase 1 precursor. Conclusion: The mRNA polyadenylation inhibitor cordycepin inhibits proliferation and survival of endometriotic cells.

Expression pattern of class I histone deacetylases in vulvar intraepithelial neoplasia and vulvar cancer: a tissue microarray study

BackgroundEpigenetic regulation is an important mechanism leading to cancer initiation and promotion. Histone acetylation by histone deacetylases (HDACs) represents an important part of it. The development of HDAC inhibitors has identified the utility of HDACs as a therapeutic target. Little is known about the epigenetic regulation of vulvar intraepithelial neoplasia (VIN) and vulvar squamous cell cancer (VSCC). In this study, the expression of class I HDACs (HDAC 1, 2 and 3) was compared in a series of VIN and VSCC tissues.MethodsA tissue micro array (TMA) with specimens from 106 patients with high-grade VIN and 59 patients with vulvar cancer was constructed. The expression of HDACs 1, 2 and 3 were analyzed with immunohistochemistry (IHC). The nuclear expression pattern was evaluated in terms of intensity and percentage of stained nuclei and was compared between vulvar preinvasive lesions and vulvar cancer.ResultsHDAC 2 expression was significantly higher in VIN than in VSCC (p < 0.001, Fishers test). Also, 88.7% (n = 94/106) of VIN samples and only 54.5% (n = 31/57) of VSCC samples were scored at the maximum level. Conversely, HDAC 3 expression was significantly higher in VSCC (93%, 53/57) compared to VIN (73.6%, 78/106, p = 0.003), whereas only a small difference in the expression of HDAC 1 was found between these two entities of vulvar neoplasia.ConclusionsThese results suggest that epigenetic regulation plays a considerable role in the transformation of VIN to invasive vulvar neoplasia.

Conjugates of cytochrome c and antennapedia peptide activate apoptosis and inhibit proliferation of HeLa cancer cells

Polycationic cell-penetrating peptides (CPPs) deliver macromolecules into cells without losing the functional properties of the cargoed macromolecule. The aim of this study was to determine whether exogenous cytochrome c is delivered to HeLa cervical carcinoma cells by the CPP antennapedia (Antp) and activates apoptosis. HeLa cervical carcinoma cells were treated with conjugated Antp-SMCC-cytochrome c (cytochrome c chemically conjugated to Antp) or with non-conjugated Antp and cytochrome c. Sensitivity to the treatments was determined by the clonogenic assay (proliferation) and by immunoblot analysis (apoptosis activation). We report that conjugated Antp-SMCC-cytochrome c activated apoptosis in HeLa cells as demonstrated by poly (ADP-ribose) polymerase 1 (PARP-1) cleavage and inhibited their proliferation. The Antp-SMCC-cytochrome c-induced apoptosis was inhibited by z-VAD-fmk, a pan-caspase inhibitor peptide. Unconjugated Antp or cytochrome c demonstrated no inhibitory effect on survival and proliferation. Our results suggest that chemical coupling of cytochrome c to CPPs may present a possible strategy for delivering cytochrome c into cells and for activating apoptosis.

Abstract 517: Anti-glycan IgM and IgG antibodies as new biomarkers for serous ovarian cancers

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL Introduction: Patients with advanced-stage serous cancers (ovarian, peritoneal and tubal) often develop ascites, a protein-rich fluid within the peritoneal cavity which causes significant morbidity and is associated with a poor prognosis. Aberrant glycosylation is a common feature of these cancers and this may impact on the humoral immune response. We hypothesized that serous cancer patients and healthy women have different profiles of anti-glycan antibodies in plasma and ascites. Method: Matched pairs of plasma and ascites were collected from 11 patients with advanced stage disease. A custom-made printed glycan array (PGA) allowed the simultaneous detection of anti-glycan antibodies (AGAs) to 203 chemically synthesised glycans, including some tumour-associated carbohydrate antigens. Identified candidate AGAs were additionally detected using a suspension array in an independent patient cohort of 230 patients. Candidates were selected by their discriminatory power between cancer and healthy controls. One top candidate was further analyzed for its biological behavior using ovarian cancer cell lines. Results: Using PGA, we detected a multitude of AGAs in both plasma and ascites. Levels of AGAs in serum and ascites correlated independent of ascites volume. Serous cancer patients had significantly different levels of plasma IgM to 31 glycans when compared to plasma of 14 healthy control patients, with IgM levels being lower in the cancer group. Significant differences in IgG plasma levels were found for 4 glycans. The trisaccharide P1, part of the P blood group system, was selected for further analyses. Plasma expression of P1 was found independent of cohort and method used. The human serous ovarian cancer cell line, IGROV1, was shown to express P1 and was subsequently sorted into P1-high, P1-low, and P1-negative subpopulations. We found that IGROV1/P1-expressing cells correlated with faster tumor cell migration and invasion. Treatment with a human anti-P1 IgM (clone P3NIL100) inhibited the proliferation of these tumour cells in vitro. Conclusion: P1 expression can be detected in ovarian cancer patients in independent of cohorts. P1 seems to be involved in cancer migration and invasion, and is therefore a potential target for ovarian cancer diagnosis and therapy. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 517. doi:1538-7445.AM2012-517