In vitro comparison of methods for sampling copper-based antimicrobial surfaces

IMPORTANCE

Self-sanitizing surfaces such as copper (Cu) are increasingly used on high-touch surfaces to prevent the spread of harmful viruses and bacteria. Being able to monitor the antimicrobial properties of Cu is fundamental in measuring its antimicrobial efficacy. Thorough investigations into reliable methods to enumerate bacteria from self-sanitizing surfaces are lacking in the literature. This study demonstrates that direct use of Petrifilm on Cu surfaces most likely revives stressed and dying bacteria, which induces increased bacterial counts. This phenomenon was not observed with indirect collection methods. Studies assessing time-kill kinetics or long-term efficacy of Cu should consider the impact of the collection method chosen.

Redundant roles of AKT1 and AKT2 in fertility, estrous cyclicity and endometrial gland development

Apoptosis and cell survival regulation are crucial processes during the estrous cycle to prepare a receptive uterus during implantation for successful recognition of pregnancy. PI3K/AKT signaling has a crucial role during gestation and AKT isoforms (1, 2 or 3) are regulated differently in the endometrium during the estrous cycle and embryo implantation. However, the specific roles of these isoforms are still unclear. We have previously shown that AKT isoforms expression during the rat estrous cycle and gestation are differently regulated. The present study aimed to establish the specific role of AKT isoforms in the mouse uterus. The hypothesis is that a dysregulation of AKT isoforms expression could cause fertility-related issues in an isoform-specific manner. With four different mouse models and in-house crossbreeding, all isoforms KO combinations (single, double and triple) were obtained in PGR expressing tissues. The results demonstrated that in absence of one or more AKT isoforms, female fertility was decreased. Mainly, we have observed smaller litter size, specifically in Akt1-2 KO mice. Additionally, we have found Akt1-2-3 KO mice to be fully infertile. Estrous cyclicity was also disrupted in Akt1-2 KO mice with longer diestrus stage. Moreover, the number of endometrial glands was decreased throughout the estrous cycle suggesting an important role in gland development for AKT1 and AKT2. Our results suggest specific roles between each isoform, but also a partially redundant function of AKT1 and AKT2 in litter size, estrous cyclicity and endometrial gland development. This highlights the importance of AKT in the physiological regulation of mouse fertility.

Pharmacologic inhibition of Akt in combination with chemotherapeutic agents effectively induces apoptosis in ovarian and endometrial cancer cell lines

The PI3K/Akt signaling pathway, the most frequently altered signaling system in human cancer, is a crucial inducer of dysregulated proliferation and neoplastic processes; however, few therapeutic strategies using PI3K/Akt inhibitors singly have been shown to be effective. The purpose of this paper was to underline the potential benefit of pharmacological modulation of the PI3K/Akt pathway when combined with specific chemotherapeutic regimens. We have studied the ability of NVP‐BEZ235 (PI3K/mTOR inhibitor) and AZD5363 (Akt inhibitor) in the sensitization of cancer cells to cisplatin and doxorubicin. Our results show that NVP‐BEZ235 sensitizes cells preferentially to cisplatin while AZD5363 sensitizes cells to doxorubicin. At equal concentrations (5 μm), both inhibitors reduce ribosomal protein S6 phosphorylation, but AZD5363 is more effective in reducing GSK3β phosphorylation as well as S6 phosphorylation. Additionally, AZD5363 is capable of inducing FOXO1 and p53 nuclear localization and reduces BAD phosphorylation, which is generally increased by cisplatin and doxorubicin. Finally, the combination of AZD5363 and doxorubicin induces apoptosis in cells and robustly reduces cell ability to clonally replicate, which underlines a potential cooperative effect of the studied compounds.

Inhibition of CRM1 activity sensitizes endometrial and ovarian cell lines to TRAIL-induced cell death

BACKGROUND

CRM1 enrichment has been shown to be indicative of invasive as well as chemoresistant tumors. On the other hand, TRAIL, a powerful and specific anti-tumoral agent, has yet to be used effectively to treat gynecological tumors in patients. In the present study, we examined if CRM1, a nuclear exporter capable of mediating protein transport, could be a relevant target to restore chemosensitivity in chemoresistant cells. We thus explored the hypothesis that CRM1-driven nuclear exclusion of tumor suppressors could lead to chemoresistance and that CRM1 inhibitors could present a novel therapeutic approach, allowing sensitization to chemotherapeutic agents.

METHODS

Ovarian cancer cell lines, as well as endometrial cancer cell lines, were treated with leptomycin B (LMB), cisplatin and TRAIL, either singly or in combination, in order to induce apoptosis. Western blot and flow cytometry analysis were used to quantify caspases activation and apoptosis induction. Immunofluorescence was used to determine nuclear localization of p53. Colony formation assays were performed to determine therapeutic effectiveness; p53 siRNA were used to establish p53 role in sensitization. Additional information from GEO database and Prognoscan allowed us to contextualise the obtained results. Finally, qRT-PCR was performed to measure apoptotic regulators expression.

RESULTS

TRAIL and LMB combination therapy lead to cleavage of caspase-3 as well as the appearance of cleaved-PARP, and thus, apoptosis. Further experiments suggested that sensitization was achieved through the synergistic downregulation of multiple inhibitor of apoptosis, as well as the activation of apoptotic pathways. p53 was enriched in the nucleus following LMB treatments, but did not seem to be required for sensitization; additional experiments suggested that p53 opposed the apoptotic effects of LMB and TRAIL. Results obtained from public data repositories suggested that CRM1 was a driver of chemoresistance and poor prognostic; DR5, on the other hand, acted as as a marker of positive prognostic.

CONCLUSIONS

Taken together, our results suggest that the use of CRM1 inhibitors, in combination to chemotherapeutic compounds, could be highly effective in the treatment of gynecological malignancies.

Regulation of the PI3K/Akt pathway during decidualization of endometrial stromal cells

Infertility is constantly increasing in Canada, where 16% of Canadian couples are experiencing difficulty conceiving. It is thought that infertility can emanate from the dysregulated communication between the embryo and the maternal endometrium. In order to allow for this window of implantation to be open at the right moment, endometrial stromal cells proliferate and differentiate by a mechanism called decidualization. Intracellular and molecular mechanisms involved in the regulation of apoptosis and cell proliferation during decidualization of the endometrium are yet to be fully understood. It has been well demonstrated previously that Akt is importantly involved in cell survival and glycogen synthesis. Akt1, Akt2 and Akt3 isoforms have distinct physiological roles; this could also be the case during decidualization and pregnancy. The aim of this study is to investigate the regulation of PI3K/Akt pathway during the decidualization process of endometrial stromal cells. Expression of Akt isoforms, Akt activity (phospho-Akt), pIκB and substrates of Akt during decidualization were measured. To our knowledge, these results are the first to suggest a decrease in levels of Akt isoforms as well as a downregulation of Akt activity in the process of decidualization of human endometrial stromal cells. We also uncovered that decidualization induced nuclear localization of p65 through the phosphorylation of IκB, its inhibitory subunit; however, Par-4, a recently uncovered regulator of cell differentiation, was displaced from the nucleus upon decidualization. Our results also suggest that HIESC cells exhibit decreased motility during decidualization and that PI3K pathway inhibition could be involved in this process. Finally, we demonstrate that specific Akt isoforms present unique effects on the successful induction of decidualization. Further analyses will involve investigations to understand the precise signaling mechanisms by which this pathway is regulated.

Genetic Deletion of Akt3 Induces an Endophenotype Reminiscent of Psychiatric Manifestations in Mice

The protein kinase B (PKB/Akt), found in three distinctive isoforms (PKBα/Akt1, PKBβ/Akt2, PKBγ/Akt3), is implicated in a variety of cellular processes such as cell development, growth and survival. Although Akt3 is the most expressed isoform in the brain, its role in cerebral functions is still unclear. In the present study, we investigated the behavioral, electrophysiological and biochemical consequences of Akt3 deletion in mice. Motor abilities, spatial navigation, recognition memory and LTP are intact in the Akt3 knockout (KO) mice. However, the prepulse inhibition, three-chamber social, forced swim, tail suspension, open field, elevated plus maze and light-dark transition tests revealed an endophenotype reminiscent of psychiatric manifestations such as schizophrenia, anxiety and depression. Biochemical investigations revealed that Akt3 deletion was associated with reduced levels of phosphorylated GSK3α/β at serine 21/9 in several brain regions, although Akt1 and Akt2 levels were unaffected. Notably, chronic administration of lithium, a mood stabilizer, restored the decreased phosphorylated GSK3α/β levels and rescued the depressive and anxiety-like behaviors in the Akt3 KO mice. Collectively, our data suggest that Akt3 might be a critical molecule underlying psychiatric-related behaviors in mice.

Chemoresistance and targeted therapies in ovarian and endometrial cancers

Gynecological cancers are known for being very aggressive at their advanced stages. Indeed, the survival rate of both ovarian and endometrial cancers is very low when diagnosed lately and the success rate of current chemotherapy regimens is not very efficient. One of the main reasons for this low success rate is the acquired chemoresistance of these cancers during their progression. The mechanisms responsible for this acquired chemoresistance are numerous, including efflux pumps, repair mechanisms, survival pathways (PI3K/AKT, MAPK, EGFR, mTOR, estrogen signaling) and tumor suppressors (P53 and Par-4). To overcome these resistances, a new type of therapy has emerged named targeted therapy. The principle of targeted therapy is simple, taking advantage of changes acquired in malignant cancer cells (receptors, proteins, mechanisms) by using compounds specifically targeting these, thus limiting their action on healthy cells. Targeted therapies are emerging and many clinical trials targeting these pathways, frequently involved in chemoresistance, have been tested on gynecological cancers. Despite some targets being less efficient than expected as mono-therapies, the combination of compounds seems to be the promising avenue. For instance, we demonstrate using ChIP-seq analysis that estrogen downregulate tumor suppressor Par-4 in hormone-dependent cells by directly binding to its DNA regulatory elements and inhibiting estrogen signaling could reinstate Par-4 apoptosis-inducing abilities. This review will focus on the chemoresistance mechanisms and the clinical trials of targeted therapies associated with these, specifically for endometrial and ovarian cancers.

Post-translational regulation of the cleaved fragment of Par-4 in ovarian and endometrial cancer cells

We recently reported the caspase3-dependent cleavage of Par-4 resulting in the accumulation of a 25kDa cleaved-Par-4 (cl-Par-4) fragment and we investigated in the present study the mechanisms regulating this fragment using cl-Par-4-expressing stable clones derived from ovarian and endometrial cancer cell lines.Cl-Par-4 protein was weakly express in all stable clones despite constitutive expression. However, upon cisplatin treatment, cl-Par-4 levels increased up to 50-fold relative to baseline conditions. Treatment of stable clones with proteasome and translation inhibitors revealed that cisplatin exposure might in fact protect cl-Par-4 from proteasome-dependent degradation. PI3K and MAPK pathways were also implicated as evidenced by an increase of cl-Par-4 in the presence of PI3K inhibitors and a decrease using MAPK inhibitors. Finally using bioinformatics resources, we found diverse datasets showing similar results to those we observed with the proteasome and cl-Par-4 further supporting our data.These new findings add to the complex mechanisms regulating Par-4 expression and activity, and justify further studies addressing the biological significance of this phenomenon in gynaecological cancer cells.

New testosterone derivatives as semi-synthetic anticancer agents against prostate cancer: synthesis and preliminary biological evaluation

Prostate cancer (PC) is a major health issue in the world. Treatments of localized PC are quite efficient and usually involve surgery, radiotherapy and/or hormonal therapy. Metastatic PC is however rarely curable to this day. Treatments of metastatic PC involve radiotherapy, chemotherapy and hormonal treatment such as orchiectomy, antiandrogens and luteinizing hormone-releasing hormone agonists. The suppression of tumor growth by hormonal treatment is efficient but overtime resistance still occurs and the disease progresses. Thus, more urgently than ever there is a need for discovery of new treatment options for castration-resistant PC (CRPC). Hence, we designed and tested a series of amide derivatives located at position 7α of testosterone as prospective "natural" or "semisynthetic" anticancer agents against CRPC with the goal of discovering therapeutic alternatives for the disease. This manuscript describes an efficient path towards the target molecules that are made in only 6 or 7 chemical steps from testosterone in good overall yields. This strategy can be used to make several compounds of interest that present higher biological activity than the classic antiandrogen; cyproterone acetate (3). The best testosterone-7α-amide was the N-2-pyridylethylamide (25) which was as active as the antiandrogen cyproterone acetate (3) on androgen-dependent LNCaP cells and 2.7 times more active on androgen-independent PC3 prostate cancer cells. The results obtained show the synthetic feasibility and the potential for future development of this unique class of semi-synthetic anticancer agents that offer the premise of new treatment modalities for patients afflicted with CRPC.

Parasporin-2 from a New Bacillus thuringiensis 4R2 Strain Induces Caspases Activation and Apoptosis in Human Cancer Cells

In previous studies, parasporin-2Aa1, originally isolated from Bacillus thuringiensis strain A1547, was shown to be cytotoxic against specific human cancer cells but the mechanisms of action were not studied. In the present study, we found that proteinase K activated parasporin-2Aa1 protein isolated from a novel B. thuringiensis strain, 4R2, was specifically cytotoxic to endometrial, colon, liver, cervix, breast and prostate cancer. It showed no toxicity against normal cells. Upon treatment with proteinase K-activated parasporin-2Aa1, morphological changes were observed and western blot analysis revealed the cleavage of poly (ADP-Ribose) polymerase, caspase-3 and caspase-9 in cancer cell lines exclusively, indicative of programmed cell death, apoptosis. Flow cytometry analyses,using propidium iodide and annexin V, as well as a caspases 3/7 assay confirmed apoptosis induction. Further analyses were performed to study survival pathways, including AKT, XIAP, ERK1/2 and PAR-4, a known inducer of apoptosis. These results indicate that parasporin-2Aa1 is a selective cytotoxic protein that induces apoptosis in various human cancer cell lines from diverse tissues.

Abstract 1958: Interaction between keratin intermediate filament proteins K8/18 and cancer related signal transduction proteins in epithelial cells

Intermediate filaments (IFs) are cytoskeletal polymers formed by a large family of proteins that are expressed in a cell differentiation and tissue specific manner. Keratins (K) are the IF proteins present in epithelial cells. They are known to provide structural supports to cells and play roles in maintaining cellular integrity against mechanical and toxic stresses. More recently, keratins have been recognized to play non-mechanical functions which include the regulation of signaling pathways that control cell growth and survival. In tumor pathology, K8 and K18 which are the only keratin present in hepatocytes were, for a long time, just considered as cell type markers. However, in recent years various studies have provided evidence that keratins should be considered as regulators of cancer cell signaling. For instance, K8/18 loss is a hallmark of epithelial mesenchymal transition (EMT) but their role in tumor progression is unclear. In an attempt to bring more insight into the function of keratins in this process, we first investigated whether K8/18 expression played an active role in EMT. Using shRNA, we produced new K8/18 stable knockdown cell lines (human endometrial carcinoma KLE, human hepatocellular carcinoma HepG2 and human cervical carcinoma HeLa cell). Our K8/18 stable knockdown model presented a hyperactivation of the PI3K/Akt/NF-κB axis. Moreover, these changes were associated with an increase in collective cell migration and invasiveness. Because of these results, we considered whether NF-κB and its activators (PI3K, Akt (1, 2, 3), pAkt, IKK (α, β, γ), IκB-α and pIκB-α) are associated with keratins in epithelial cells. Using immunoprecipitation and immunofluorescence, our current results show that pAkt, NF-κB and IKKβ are indeed associated with keratins. Taken together, these results support the hypothesis that keratin intermediate filament proteins provide a platform for these proteins involved in signal transduction. Further studies will be done to determine if posttranslational modifications that affect keratins (K8/18 phosphorylation on specific serines and/or K18 O-glycosylation) interfere with their association to signaling protein and transcription factors previously found. Changes in K8/18 posttranlational modifications and their association with different proteins could be important determinants in cancer progression of epithelial cells. This work was supported by CRSNG grants to MC and EA.

Citation Format: Stephanie Lamontagne, Anne-Marie Fortier, Sophie Parent, Eric Asselin, Monique Cadrin. Interaction between keratin intermediate filament proteins K8/18 and cancer related signal transduction proteins in epithelial cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1958. doi:10.1158/1538-7445.AM2015-1958

Abstract 3810: Leptomycin B sensitizes ovarian and endometrial cancer cells to TRAIL-induced apoptosis

One of our most important line of defense against cancer is the use of chemotherapy. Resistance to these drugs represents, however, a fundamental limitation in our ability to treat tumors, especially in ovarian cancer (OC) as well as in endometrial cancer (EC). Both of these cancers display high mortality rate due to the establishment of chemoresistance. It is thus of utmost importance that we develop new approaches to overcome this problem and restore chemosensitivity in cancer cells. Nuclear transport has been shown to be exceedingly important in cell fate dynamics. CRM1, also known as XPO1, is a nuclear export receptor that recognize leucine-rich domain known as “Nuclear Export Signal”. Indeed, substantial CRM1 enrichment is indicative of highly invasive and resistant tumors and is generally suggestive of lower chance of survival. On the other hand, Par-4, an exceptionally rarely mutated protein capable of inducing cell death only in transformed cells while sparing normal cells, is suggested to be activated upon nuclear localization; it is thus considered a powerful, cancer-specific, inducer of cell death. Recent findings suggest that reinstating the ability of Par-4 to accumulate in the nucleus could re-establish its capacity to induce apoptosis. Our hypothesis was that CRM1 nuclear exclusion of Par-4 could be an acquired resistance mechanism in cancer cells.

To explore this hypothesis, we first treated various OC and EC cell types with Leptomycin B to observe whether Par-4 would accumulate to the nucleus; to this end, we performed immunofluorescence as well as subcellular protein fractionations. The obtained results suggested that Par-4 was enriched in the nucleus of cells following Leptomycin B treatments. We then treated multiple OC and EC cell lines with a combination of Leptomycin B, cisplatin and TRAIL recombinant protein to determine if Par-4 enrichment through CRM-1 inhibition could sensitizes tumor cells through either extrinsic or intrinsic death pathways. We then assessed cell death and Par-4 cleavage, an important event in Par-4 induced cell death, using western blot and confirmed the results pertaining to cell death by flow cytometry (Annexin V/PI). The obtained results suggested that the combination of Leptomycin B and TRAIL largely increased cell death and apoptosis when compared to their treatment alone.

Taken together, these results suggest that CRM1 control export of various tumor suppressors including Par-4, and this could be a putative mechanism responsible for the establishment of chemoresistance in OC as well as EC. The use of CRM1 inhibitors in combination to chemotherapeutic drug treatments could be an attractive strategy to reverse chemoresistance in the context of gynecological cancer therapy.

Citation Format: François Fabi, France-Hélène Joncas, Sophie Parent, Valérie Leblanc, Eric Asselin. Leptomycin B sensitizes ovarian and endometrial cancer cells to TRAIL-induced apoptosis. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3810. doi:10.1158/1538-7445.AM2015-3810

Functional specificity of Akt isoforms in cancer progression

Akt/PKB kinases are central mediators of cell homeostasis. There are three highly homologous Akt isoforms, Akt1/PKBα, Akt2/PKBβ and Akt3/PKBγ. Hyperactivation of Akt signaling is a key node in the progression of a variety of human cancer, by modulating tumor growth, chemoresistance and cancer cell migration, invasion and metastasis. It is now clear that, to understand the mechanisms on how Akt affects specific cancer cells, it is necessary to consider the relative importance of each of the three Akt isoforms in the altered cells. Akt1 is involved in tumor growth, cancer cell invasion and chemoresistance and is the predominant altered isoform found in various carcinomas. Akt2 is related to cancer cell invasion, metastasis and survival more than tumor induction. Most of the Akt2 alterations are observed in breast, ovarian, pancreatic and colorectal carcinomas. As Akt3 expression is limited to some tissues, its implication in tumor growth and resistance to drugs mostly occurs in melanomas, gliomas and some breast carcinomas. To explain how Akt isoforms can play different or even opposed roles, three mechanisms have been proposed: tissue-specificity expression/activation of Akt isoforms, distinct effect on same substrate as well as specific localization through the cyto-skeleton network. It is becoming clear that to develop an effective anticancer Akt inhibitor drug, it is necessary to target the specific Akt isoform which promotes the progression of the specific tumor.

Exploring the synthesis and anticancer potential of L-tyrosine-platinum(II) hybrid molecules

The search for new specific chemotherapeutic drugs designed to minimize the toxic side effects resulting from chemotherapy is still a subject of intense research. The objective of the current study was to design a non-steroidal-platinum(II) derivative that would target the estrogen receptor alpha (ERα) without triggering estrogenic cell proliferation. For this purpose, the amino acid L-tyrosine was modified and attached to a cisplatin analog. Hence, the L-tyrosine portion of the molecule could possibly act as a transporter to target the ERα protein and, by doing so concentrate the cytotoxic moiety to hormone-dependent breast cancer cells. Herein, we describe three different alternative methodologies that were used to make these new anticancer molecules. The L-tyrosine-Pt(II) hybrid 5b was made in four steps with 36% overall yield by the first method, in six steps with 11% overall yield by the second method and, in four steps with 23% overall yield by the third method. Preliminary biological activity on breast cancer cell lines indicated that the final hybrids (5a and 5b) were unfortunately inactive but their platinum(II) precursors (14a and 14b) showed activity similar to that of cisplatin.

Expression, activation, and role of AKT isoforms in the uterus

The three isoforms of AKT: AKT1, AKT2, and AKT3, are crucial regulators of both normal and pathological cellular processes. Each of these isoforms exhibits a high level of homology and functional redundancy with each other. However, while being highly similar and structurally homologous, a rising amount of evidence is showing that each isoform possesses specific targets as well as preferential subcellular localization. The role of AKT has been studied extensively in reproductive processes, but isoform-specific roles are yet to be fully understood. This review will focus on the role of AKT in the uterus and its function in processes related to cell death and proliferation such as embryo implantation, decidualization, endometriosis, and endometrial cancer in an isoform-centric manner. In this review, we will cover the activation of AKT in various settings, localization of isoforms in subcellular compartments, and the effect of isoform expression on cellular processes. To fully understand the dynamic molecular processes taking place in the uterus, it is crucial that we better understand the physiological role of AKT isoforms as well as their function in the emergence of diseases.

Abstract 3347: Post-translational modifications of Akt isoform in chemoresistance of endometrial cancer

Endometrial cancer is ranked fourth in importance among all types of cancer in women. This cancer is the most prevalent gynecological cancer. Akt is an inactive cytosolic serine/threonine kinase that plays a crucial role in cell fate by promoting cellular survival and proliferation. There are three Akt isoforms (1,2 and 3). This protein acts as a key regulator of numerous cellular phenotypes associated with cancer, such as cell proliferation, growth, metabolism, angiogenesis, malignant transformation and chemoresistance. It has been shown that Akt polyubiquitination is increased in cells treated with IGF-1. This ubiquitination is associated with an augmentation in the phosphorylation status of Akt. More and more evidence show that ubiquitination plays a pivotal role in kinase activation. In this study we observed ubiquitinated Akt (Ub-Akt) in the nucleus following IGF-1 treatment in the nucleus of endometrial cell lines (Ishikawa and KLE). We have established the ubiquitination pattern for the three Akt isoforms and their location in the cells. We also showed a cleaved fragment of Akt following cisplatin treatment in the same cell lines.

Using western blot analyses, we observed a band at 60kDa corresponding to Akt and also other upper bands corresponding to Ub-Akt, in the nucleus of different endometrial cell lines. We have analyzed the pattern of two endometrial carcinoma (KLE and Ishikawa) and a cervical cancer cell line (HeLa). We found that both Akt1 and Akt3 were ubiquitinated in most of the cell lines. On the other hand, Akt2 was not ubiquitinated in any cell lines. We have used siRNA technology to knockdown each Akt isoform and characterized the loss of each isoform on the ubiquitination pattern for each cell line. We also treated cell lines with cisplatin to see which one of the three isoforms could be involved in chemoresistance and if Akt ubiquitination status could be involved in this process. We have separated fractions of the cytosol from the nucleus for each sample to investigate distribution of Ub-Akt isoforms in each cell line and confirmed the presence of Ub-Akt1 and -3 in the nucleus. We have also co-immunoprecipitated each Akt isoform and Ubiquitin to determine the exact ubiquitination pattern in cancer cells. KLE and Ishikawa had similarities in their pattern. Using immunoprecipitation, we observed that Akt1 was cleaved following cisplatin treatment. We observed that chemosentisitive cells had more cleaved Akt then chemoresistant lines. In conclusion, we are the first to establish a difference in the ubiquitination pattern for the different Akt isoform in the nucleus of endometrial cancer. We are also the first to show a cleavage of Akt isoforms linked to chemosensitive status of endometrial cancer. This study will form the basis for future investigations to determine the role of specific post-translationnal modifications of Akt isoforms in the endometrial cancer.

Citation Format: Jérôme Grenier-Naud, Sophie Parent, Eric Asselin. Post-translational modifications of Akt isoform in chemoresistance of endometrial cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3347. doi:10.1158/1538-7445.AM2014-3347

Abstract 1140: Par-4 mediates EMT in response to TGF-β stimulation

Endometrial cancer is the most common cancer affecting the female genital tract; this disease also stands as the fourth most frequent cancer affecting occidental women. Endometrial cancer is generally well manageable; however, the high metastatic potential of endometrial tumors represents one of the major hurdles in the treatment of this disease. The epithelial to mesenchymal transition (EMT) has been considered for a long time as a central mechanism by which cancer cells acquire invasive abilities necessary for metastasis formation. Multiple regulatory networks dictate this complex process; however TGF-β has been shown to be one of the most important inductor of EMT in cancer cells. Still, the process by which TGF-β induces this transition has yet to be fully understood. Our study demonstrates that TGF-β upregulates the expression of Par-4, a tumor suppressor protein concomitantly with the onset of EMT. Four uterine cell lines (Hec-1-a, KLE, HeLa, HIESC), one ovarian cell line (SKOV-3) and one breast cell line (MCF7) were used in this study. We first investigated the effect of exogenous TGF-β treatment on these cell lines to determine its effect on Par-4 expression. We've observed that TGF-β increased Par-4 levels in every cell lines. Preliminary analysis determined that this regulation was made through both Smad4 and p65, which was confirmed by the use of siRNA. We've also demonstrated that this regulation was made at the transcriptional level by RT-qPCR. We then sought to confirm the effect of TGF-β on our cell lines and its effect on EMT induction. Our experiments demonstrated that TGF-β promotes EMT as suggested by the upregulation of multiple EMT markers. Transfections using Par-4 expression plasmids induced similar changes, indicating the involvement of Par-4 in TGF-β mediated EMT induction. We then proceeded to assess the effect of Par-4 knockdown concurrent with exogenous TGF-β stimulation. This experiment revealed that Par-4 knockdown reduced the ability of TGF-β to induce Snail expression, further demonstrating the importance of Par-4 in the process of TGF-β mediated EMT. To conclude the study, we sought to understand the effect of XIAP in this process. Our experiments uncovered that XIAP regulates full length Par-4 levels through the inhibition of its caspase-mediated cleavage. Furthermore, the inhibition of XIAP by siRNAs, and thus of Par-4 cleavage, resulted in the reduction of Par-4 EMT inducing capabilities. In conclusion, our study proposes a novel function of Par-4 as an inductor of EMT in multiple cell lines.

Citation Format: François Fabi, Parvesh Chaudhry, Mohan Singh, Eric Asselin. Par-4 mediates EMT in response to TGF-β stimulation. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1140. doi:10.1158/1538-7445.AM2014-1140

Prostate apoptosis response-4 mediates TGF-β-induced epithelial-to-mesenchymal transition

A growing body of evidence supports that the epithelial-to-mesenchymal transition (EMT), which occurs during cancer development and progression, has a crucial role in metastasis by enhancing the motility of tumor cells. Transforming growth factor-β (TGF-β) is known to induce EMT in a number of cancer cell types; however, the mechanism underlying this transition process is not fully understood. In this study we have demonstrated that TGF-β upregulates the expression of tumor suppressor protein Par-4 (prostate apoptosis response-4) concomitant with the induction of EMT. Mechanistic investigations revealed that exogenous treatment with each TGF-β isoform upregulates Par-4 mRNA and protein levels in parallel levels of phosphorylated Smad2 and IκB-α increase. Disruption of TGF-β signaling by using ALK5 inhibitor, neutralizing TGF-β antibody or phosphoinositide 3-kinase inhibitor reduces endogenous Par-4 levels, suggesting that both Smad and NF-κB pathways are involved in TGF-β-mediated Par-4 upregulation. NF-κB-binding sites in Par-4 promoter have previously been reported; however, using chromatin immunoprecipitation assay we showed that Par-4 promoter region also contains Smad4-binding site. Furthermore, TGF-β promotes nuclear localization of Par-4. Prolonged TGF-β3 treatment disrupts epithelial cell morphology, promotes cell motility and induces upregulation of Snail, vimentin, zinc-finger E-box binding homeobox 1 and N-Cadherin and downregulation of Claudin-1 and E-Cadherin. Forced expression of Par-4, results in the upregulation of vimentin and Snail expression together with increase in cell migration. In contrast, small interfering RNA-mediated silencing of Par-4 expression results in decrease of vimentin and Snail expression and prevents TGF-β-induced EMT. We have also uncovered a role of X-linked inhibitor of apoptosis protein in the regulation of endogenous Par-4 levels through inhibition of caspase-mediated cleavage. In conclusion, our findings suggest that Par-4 is a novel and essential downstream target of TGF-β signaling and acts as an important factor during TGF-β-induced EMT.

Liver glucagon receptors (GluR): effect of exercise and fasting on binding characteristics, GluR-mRNA, and GluR protein content in rats

The purpose of the study was to investigate the effects of acute exercise and fasting on glucagon receptor (GluR) binding characteristics, GluR-mRNA, and protein content in rat liver. Liver homogenates were prepared and plasma membranes were purified by aqueous 2-phase affinity partitioning in rats fed at rest (control) and after 180 min of swimming exercise and 24 h of fasting (7 rats/group). Saturation curve of plasma membranes incubated with [125I]-glucagon showed significant higher GluR density following exercise and fasting than in the control group (8.19±0.29 and 8.01±0.65 vs. 3.09±0.12 pmol/mg of proteins, respectively). When compared to control rats, GluR Kd was also higher following exercise and fasting (0.46±0.05 and 0.56±0.13 vs. 0.33±0.05 nM, respectively; significantly different for fasting only). Expression of GluR-mRNA and protein content were both significantly higher (~100% and ~90%, respectively) following the 24-h fast than in the control rats, but not following exercise. These results, in line with the literature showing an increased sensitivity of the liver to glucagon following exercise and fasting, indicate that an increased density of GluR on plasma membranes can be obtained by 2 complementary mechanisms: externalization of pre-existing GluR from intracellular pools operative in response to the prolonged exercise, and de novo synthesis of GluR operative only in response to fasting. The reduction in plasma insulin concentration and/or depletion of liver glycogen stores, which results from both prolonged exercise and fasting, could be involved in the control of these mechanisms.

ERα-targeted therapy in ovarian cancer cells by a novel estradiol-platinum(II) hybrid

As we previously showed, we have synthesized a new family of 17β-estradiol-platinum(II) hybrids. Earlier studies revealed the VP-128 hybrid to show high efficiency compared with cisplatin toward hormone-dependent breast cancer cells. In the present research, we have studied the antitumor activity of VP-128 in vitro and in vivo against ovarian cancer. In nude mice with ovarian xenografts, VP-128 displayed selective activity toward hormone-dependent tumors and showed higher efficiency than cisplatin to inhibit tumor growth. Similarly, in vitro, transient transfection of estrogen receptor (ER)-α in ERα-negative A2780 cells increased their sensitivity to VP-128-induced apoptosis, confirming the selectivity of VP-128 toward hormone-dependent tumor cells. In agreement, Western blot analysis revealed that VP-128 induced higher caspase-9, caspase-3, and poly (ADP-ribose) polymerase cleavage compared with cisplatin. The activation of caspase-independent apoptosis was also observed in ERα-negative A2780 cells, in which VP-128 rapidly induced the translocation of apoptosis-inducing factor to the nucleus. Conversely, subcellular localization of apoptosis-inducing factor was not modified in ERα-positive Ovcar-3 cells. We also discovered that VP-128 induces autophagy in ovarian cancer cells because of the formation of acidic vesicular organelles (AVOs) and increase of Light Chain 3B-II protein responsible for the formation of autophagosomes; pathways related to autophagy (AKT and mammalian target of rapamycin) were also down-regulated, supporting this mechanism. Finally, the inhibition of autophagy using chloroquine increased VP-128 efficiency, indicating a possible combination therapy. Altogether these results highlight the beneficial value of VP-128 for the treatment of hormone-dependent ovarian cancers and provide preliminary proof of concept for the efficient targeting of ERα- by 17β-estradiol-Pt(II)-linked chemotherapeutic hybrids in these tumors.

Cisplatin-induced caspase activation mediates PTEN cleavage in ovarian cancer cells: a potential mechanism of chemoresistance

BACKGROUND

The phosphatase and tensin homolog deleted on chromosome 10 (PTEN) tumor suppressor protein is a central negative regulator of the PI3K/AKT signaling cascade and suppresses cell survival as well as cell proliferation. PTEN is found to be either inactivated or mutated in various human malignancies. In the present study, we have investigated the regulation of PTEN during cisplatin induced apoptosis in A2780, A270-CP (cisplatin resistant), OVCAR-3 and SKOV3 ovarian cancer cell lines.

METHODS

Cells were treated with 10μM of cisplatin for 24h. Transcript and protein levels were analysed by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) and western blotting, respectively. Immunofluorescence microscopy was used to assess the intracellular localization of PTEN. Proteasome inhibitor and various caspases inhibitors were used to find the mechanism of PTEN degradation.

RESULTS

PTEN protein levels were found to be decreased significantly in A2780 cells; however, there was no change in PTEN protein levels in A2780-CP, OVCAR-3 and SKOV3 cells with cisplatin treatment. The decrease in PTEN protein was accompanied with an increase in the levels of AKT phosphorylation (pAKT) in A2780 cells and a decrease of BCL-2. Cisplatin treatment induced the activation/cleavage of caspase-3, -6, -7, -8, -9 in all cell lines tested in this study except the resistant variant A2780-CP cells. In A2780 cells, restoration of PTEN levels was achieved upon pre-treatment with Z-DEVD-FMK (broad range caspases inhibitor) and not with MG132 (proteasome inhibitor) and by overexpression of BCL-2, suggesting that caspases and BCL-2 are involved in the decrease of PTEN protein levels in A2780 cells.

CONCLUSION

The decrease in pro-apoptotic PTEN protein levels and increase in survival factor pAKT in A2780 ovarian cancer cells suggest that cisplatin treatment could further exacerbate drug resistance in A2780 ovarian cancer cells.

Abstract 293: TGF-b regulates Par-4 expression through XIAP in ovarian and endometrial cancers

The lethality of gynecological malignancies can be explained by their propensity to develop chemioresistance and metastases. The loss of apoptotic pathways is one of the major underlying mechanisms by which tumors become resistant to treatments. This loss can be explained by the silencing of pro-apoptotic proteins that would normally contrive the cell into suicide. Par-4 is a tumor suppresor protein that is widely expressed but only functionally silenced in most endometrial cancer. This protein presents the unique ability to induce apoptosis selectively in cancer cells. We have recently demonstrated that Par-4 is a substrate of caspase-3 and the resulting cleaved fragment retains its apoptotic-inducing capabilities. We have also evidenced that TGF-β, a known instigator of EMT, regulates the invasiveness of endometrial cancer cells and Par-4 expression. TGF-β has also been shown to increase the expression of XIAP, an important promoter of cell survival and invasiveness in endometrial cancer. In this study, we have investigated the effect of TGF-ß and XIAP on Par-4 expression in ovarian and endometrial cancer.

We have performed rescue experiment in which MEFs cells from XIAP KO mice were cultured and transfected with either an empty plasmid, a wild-type XIAP plasmid or a XIAP mutated RING domain plasmid. We have then submitted these cells to cisplatin treatment. In the empty vector transfectants, we have found that the absence of XIAP results in Par-4 cleavage, increased cleaved caspase-3 and cleaved PARP. The rescue of XIAP inhibited the apoptotic machinery and Par-4 cleavage thus resulting in increased chemoresistance. This effect was reversed using the mutated XIAP plasmid. We have also treated endometrial cancer cells (HeLa, KLE) with TGF-ß3 and observed an higher expression of EMT markers such as Snail, Vimentin and N-Cadherin; Par-4 was also upregulated by TGF-ß3. Finally, we have overexpressed ovarian A2780 cancer cells with Par-4 plasmid, which resulted in the upregulation of Snail and Vimentin. We confirmed these results using Par-4 siRNA and found that Snail and Vimentin expression were reduced.

Altogether, results of the present study shed new light in the underlying mechanisms of Par-4 regulation and apoptosis induction. The assembled data also suggests that TGF-β plays a cardinal role in the regulation of Par-4 expression, which regulates EMT in gynecological cancers.

Citation Format: Francois Fabi, Sophie Parent, Valérie Leblanc, Eric Asselin. TGF-b regulates Par-4 expression through XIAP in ovarian and endometrial cancers. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 293. doi:10.1158/1538-7445.AM2013-293

Abstract 5160: Claudin1 induces cell motility and invasion through PI3K/Akt/NFkB signaling in keratin-depleted carcinoma cell lines

In the early steps of metastasis, carcinoma cells undergo through a dedifferentiation process called ‘epithelial-mesenchymal transition’ (EMT). Among all phenotypic changes associated with this transition, the reduction or loss of keratin expression is often considered as a histological and biochemical feature for tumor cells that are going through an EMT. Keratins are epithelial-specific intermediate filament proteins which are expressed in a tissue-specific manner. Keratins 8 and 18 (K8/18) are typically co-expressed as the primary keratin pair in simple epithelial cells and their expression is maintained during malignant transformation until the tumor become invasive. As part of the cytoskeleton, keratins are important for the integrity of epithelial cells and tissues. Moreover, a number of keratins are involved in intracellular signaling pathways which regulates cell growth and death. In recent years, studies provided evidence that keratins should not be considered only as markers but also as regulators of cancer cell signaling.In the present study, we investigated whether K8/18 expression play an active role in EMT. We used RNA interference approach targeted against K8/18 to mimic keratin loss during EMT in two different epithelial cancer cell lines. Using in vitro wound healing and matrigel invasion assays, we observed that K8/18 stable knockdown increases collective migration and invasiveness of epithelial cancer cells without modulating EMT markers. Interestingly, we identified the tight junction protein claudin1 as a regulator of these processes. Indeed, claudin1 is highly increased and mislocalized in K8/18-depleted cells and it promotes membrane targeting and activation of Akt1 and Akt3. Claudin1 also induces NFkB nuclear translocation in a PI3K dependent manner. Therefore, NFkB transcriptional activity is increased in K8/18-knockdown cells as shown by luciferase reporter assay, leading to MMP2 and MMP9 expression. This led to our proposal of a model in which K8/18 loss promotes collective migration of epithelial cancer cell in a different way than an EMT, by increasing directional migration and intercellular cohesion. At the leading edge of the migrating cell sheet, K8/18 loss improves PI3K/Akt activation involved in the direction of movement and local matrix degradation through NFkB activity. In the following rows, K8/18 knockdown increases claudin1 at the cell membrane which strengthens cell cohesion.To our knowledge, these results represent the first indication that K8/18 can influence the phenotype of epithelial cancer cells at a transcriptional level and strongly indicate that in cancer, keratins should not be considered only as markers of differentiation but also as key regulators in cancer progression.

Citation Format: Anne-Marie Fortier, Monique Cadrin, Eric Asselin. Claudin1 induces cell motility and invasion through PI3K/Akt/NFkB signaling in keratin-depleted carcinoma cell lines. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5160. doi:10.1158/1538-7445.AM2013-5160

Keratin 8 and 18 loss in epithelial cancer cells increases collective cell migration and cisplatin sensitivity through claudin1 up-regulation

Keratins 8 and 18 (K8/18) are simple epithelial cell-specific intermediate filament proteins. Keratins are essential for tissue integrity and are involved in intracellular signaling pathways that regulate cell response to injuries, cell growth, and death. K8/18 expression is maintained during tumorigenesis; hence, they are used as a diagnostic marker in tumor pathology. In recent years, studies have provided evidence that keratins should be considered not only as markers but also as regulators of cancer cell signaling. The loss of K8/18 expression during epithelial-mesenchymal transition (EMT) is associated with metastasis and chemoresistance. In the present study, we investigated whether K8/18 expression plays an active role in EMT. We show that K8/18 stable knockdown using shRNA increased collective migration and invasiveness of epithelial cancer cells without modulating EMT markers. K8/18-depleted cells showed PI3K/Akt/NF-κB hyperactivation and increased MMP2 and MMP9 expression. K8/18 deletion also increased cisplatin-induced apoptosis. Increased Fas receptor membrane targeting suggests that apoptosis is enhanced via the extrinsic pathway. Interestingly, we identified the tight junction protein claudin1 as a regulator of these processes. This is the first indication that modulation of K8/18 expression can influence the phenotype of epithelial cancer cells at a transcriptional level and supports the hypothesis that keratins play an active role in cancer progression.

Involvement of Akt isoforms in chemoresistance of endometrial carcinoma cells

OBJECTIVE

In tumors, upstream regulation of Akt is affected by oncogenic events which lead to its constitutive activation and promote cell survival. Since studies have demonstrated that the three Akt isoforms exhibit different physiological functions, Akt isoforms may contribute differently in chemoresistance. The objective of the study was to determine the role of each Akt isoforms in chemoresistance.

METHODS

We stably transfected the chemoresistant KLE endometrial carcinoma cells with specific shRNAs for Akt1, Akt2 or Akt3. Alternatively, we stably transfected the chemosensitive Hec-1-A endometrial carcinoma cells, in which no Akt activity is detected, with constitutively active Akt expression vectors for each isoform.

RESULTS

We demonstrated that Akt1 and Akt2 downregulation by RNAi highly sensitizes KLE cells to cisplatin by inducing the activation of pro-apoptotic factors such as the cleavage of caspases-3, -6, -9 and PARP; downregulation of all Akt isoforms leads to increased sensitivity to doxorubicin while only Akt1-2 downregulation increases taxol sensitivity. Proliferation of Akt1, and mostly Akt2 deficient cells was affected by cisplatin treatment. Constitutive Akt1 or Akt2 expression led to an increased resistance to apoptosis. Akt isoforms have been shown to influence migration in other cancer cells. We showed that Akt2 blocks cell motility, while Akt1-3 had less effect on our endometrial cancer cell models.

CONCLUSION

Our findings highlight the contribution of Akt1 and Akt2 in the molecular mechanisms that govern chemoresistance of endometrial carcinomas. Furthermore, Akt isoform-specific transfectants will provide a strong model to determine the involvement of each Akt isoform in tumor progression and metastasis.

Abstract 83: Differential regulation of PTEN in ERα positive and negative ovarian cancer cells during cisplatin induced apoptosis

The phosphatase and tensin homolog deleted on chromosome 10 (PTEN) tumor suppressor is a central negative regulator of the PI3K/AKT signaling cascade and suppresses cell survival as well as cell proliferation. PTEN is found to be either inactivated or mutated in various human malignancies. In the present study we have investigated the regulation of PTEN levels during cisplatin induced apoptosis in estrogen receptor alpha (ERα) positive (OVCAR-3 and SKOV-3) and negative (A2780 and A270-CP) ovarian cancer cell lines. Cells were treated with 10μM cisplatin for 24hrs. Transcript and protein levels were analysed by reverse transcriptase-polymerase chain reaction (RT-PCR) and western blotting, respectively. The results showed that PTEN levels were significantly decreased in ERα-negative A2780 cells at both the transcript and protein levels; however, there was no change in PTEN levels in ERα-positive cells and cisplatin resistant cells (A2780-CP) in the presence of cisplatin. The decrease in PTEN was accompanied with an increase in the levels of Akt phosphorylation in A2780 cells. Cisplatin treatment induced the activation of caspase-3, -7, -8, -9 and cleavage of Parp in all the cell lines tested in the study except A2780-CP cells. In A2780 cells, restoration of PTEN levels was achieved upon pre-treatment with Z-VAD-fmk (caspase inhibitor) and not with MG132 (proteasome inhibitor), suggesting that, in addition to the regulation of PTEN at transcript level, caspases are also involved in the decrease of PTEN protein levels in A2780. The decrease in pro-apoptotic PTEN levels both at the transcriptional and post-translational levels and increase in survival factor pAkt in ERα-negative ovarian cancer cells suggest that cisplatin treatment could further exacerbates drug resistance in ERα-negative ovarian cancer cells.

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 83. doi:1538-7445.AM2012-83

Abstract 3995: C-terminal fragment of prostate apoptosis response-4 (Par-4) generated by caspase-3 cleavage induces apoptosis in cancer cells

Prostate apoptosis response-4 (Par-4) is a ubiquitously expressed pro-apoptotic tumor suppressor protein. Previously, we have shown that Par-4 undergoes caspase-3 mediated cleavage in normal and cancer cells. In the present study, we demonstrated that caspase-3 generated cleaved fragment of Par-4 displays apoptotic activity. Hela cells were transiently transfected with empty or Myc tagged C-terminal fragment of Par-4. The results from immunofluorescence studies revealed that the cleaved fragment of Par-4 is predominantly localized in the nuclear compartment of the cells. Further, cells expressing C-terminal Par-4 fragment underwent significant apoptosis as compared to empty vector transfected cells as measured by flow cytometry using annexin V/PI staining. Next, we tested whether C-terminal fragment of Par-4 follows similar mechanism of apoptosis induction as the full length Par-4 by the inhibition of protein kinase C (PKC)/NF-κB pathway. Western blot analysis revealed that the overexpression of C-terminal Par-4 fragment reduced the protein levels of Bcl-2 and FLIP as compared to empty vector transfected cells. Overexpression of the C-terminal Par-4 fragment also reduced the levels of phosphorylated IαBβ, however, there was no change in the levels of total IαBβ. Interestingly, C-terminal fragment of Par-4 prevented the nuclear mobilization of NF-κB (p65) compared to empty vector transfected cells. On the other hand, NF-κB (p50) protein levels were found to be decreased in cells expressing the C-terminal Par-4 fragment suggesting that C-terminal fragment of Par-4 possesses pro-apoptotic activity and regulates apoptotic induction by inhibiting the nuclear localization and activity of NF-κB in a manner similar to wild type full length Par-4. To conclude, our data suggest that caspase-3 mediated cleavage of Par-4 results in nuclear localization of C-terminal Par-4 fragment which possesses pro-apoptotic activity.

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 3995. doi:1538-7445.AM2012-3995

Design of novel tyrosine-nitrogen mustard hybrid molecules active against uterine, ovarian and breast cancer cell lines

L-para-Tyrosine was linked to ortho-hydroxyaniline, meta-hydroxyaniline and para-hydroxyaniline giving three distinct tyrosinamide molecules. The new extended amino acid derivatives were constructed to imitate, in part, the estradiol (E(2), the natural female sex hormone) nucleus. The resulting tyrosinamides were then linked to chlorambucil either directly, or via a 5 and 10 carbon atoms spacer chain. This was done in an attempt to target cancerous cells expressing the estrogen receptor alpha (ERα) and to obtain a more specific chemotherapeutic agent. The tyrosinamide-chlorambucil molecules were designed and synthesized in good yields, according to two different approaches. The novel compounds were evaluated for their anticancer efficacy in hormone-dependent and hormone-independent (ER+; MCF-7 and ER-; MDA-MB-231) breast cancer cell lines. Interestingly, the meta-hydroxyphenyl-tyrosinamide-chlorambucil derivatives were more active than the ortho- and para- analogs. The molecules bearing a 5 carbon atoms spacer were selected for additional biological study using a panel of female cancerous cells; breast (ZR-75-1, MDA-MB-436, MDA-MB-468), ovarian (OVCAR-3, A2780) and uterine (Ishikawa, HEC-1A). It was discovered that for breast cancer cells, the new compounds were up to 4.2 times more active than chlorambucil itself.

Ubiquitin-proteasomal degradation of COX-2 in TGF-β stimulated human endometrial cells is mediated through endoplasmic reticulum mannosidase I

Cyclooxygenase (COX)-2 is a key regulatory enzyme in the production of prostaglandins (PG) during various physiological processes. Mechanisms of COX-2 regulation in human endometrial stromal cells (human endometrial stromal cells) are not fully understood. In this study, we investigate the role of TGF-β in the regulation of COX-2 in human uterine stromal cells. Each TGF-β isoform decreases COX-2 protein level in human uterine stromal cells in Smad2/3-dependent manner. The decrease in COX-2 is accompanied by a decrease in PG synthesis. Knockdown of Smad4 using specific small interfering RNA prevents the decrease in COX-2 protein, confirming that Smad pathway is implicated in the regulation of COX-2 expression in human endometrial stromal cells. Pretreatment with 26S proteasome inhibitor, MG132, significantly restores COX-2 protein and PG synthesis, indicating that COX-2 undergoes proteasomal degradation in the presence of TGF-β. In addition, each TGF-β isoform up-regulates endoplasmic reticulum (ER)-mannosidase I (ERManI) implying that COX-2 degradation is mediated through ER-associated degradation pathway in these cells. Furthermore, inhibition of ERManI activity using the mannosidase inhibitor (kifunensine), or small interfering RNA-mediated knockdown of ERManI, prevents TGF-β-induced COX-2 degradation. Taken together, these studies suggest that TGF-β promotes COX-2 degradation in a Smad-dependent manner by up-regulating the expression of ERManI and thereby enhancing ER-associated degradation and proteasomal degradation pathways.

Synthesis, antiproliferative activity and estrogen receptor α affinity of novel estradiol-linked platinum(II) complex analogs to carboplatin and oxaliplatin. Potential vector complexes to target estrogen-dependent tissues

In the course of efforts to develop 17β-estradiol-linked to anticancer agents targeting estrogen-dependent tissue, we identified three estradiol-linked platinum(II) complex analogs to cisplatin (E-CDDP) derivatives namely: VP-128 (1), CD-38 (2) and JMP-39 (3) that exhibit potent in vitro and in vivo (for derivative VP-128) activity along with interaction with the estrogen receptor α (ERα). In this study, we prepared and biologically evaluated two novel classes of estradiol-linked platinum(II) complex analogs to carboplatin (E-CarboP, 1a-3a) and oxaliplatin (E-OxaP, 1b-3b). E-CarboP and E-OxaP were designed and based on the estradiol-linker scaffold of E-CDDP derivatives previously identified. Consequently, we assessed the importance of the nature of platinum(II) salt on the antiproliferative activity on MCF-7 and MDA-MB-231 human mammary carcinoma cell lines together with affinity for the ERα by replacing the dichloroplatinum(II) moiety by a cyclobutane-1,1-dicarboxylateplatinum(II) or an oxalateplatinum(II) moiety. Except for compound 3b which is inactive at the concentration tested, the antiproliferative activity of all compounds on both human mammary carcinomas cell lines are in micromolar range and are more active than carboplatin and oxaliplatin alone but less active that their E-CDDP counterparts (1-3). In addition, E-CarboP derivatives 1a-3a show very low affinity for ERα whereas E-OxaPs 1b and 2b show higher affinity for ERα than their parents E-CDDPs (1-2), suggesting that the nature of the platinum(II) salt involved in the vector complexes is extremely important to both retain significant antiproliferative activity and selectivity for the ERα and possibility to target estrogen-dependent tissues. Finally, E-OxaPs 1b and 2b are potentially promising alternatives vector complexes to target estrogen-dependent tissues.

Cisplatin increases B-cell-lymphoma-2 expression via activation of protein kinase C and Akt2 in endometrial cancer cells

Human carcinomas often show resistance to cisplatin and Bcl-2 is associated with resistance to cisplatin. However, Bcl-2 regulation on cisplatin treatment in human cancers is unknown. Here, we show a novel mechanism by which cisplatin treatment promotes resistance by increasing the expression of Bcl-2 mRNA. Bcl-2 mRNA and protein expression was increased in cisplatin-resistant endometrial cancer cell lines (KLE and HEC-1-A), but not in cisplatin-sensitive cell line (Ishikawa). Cisplatin-mediated increase in Bcl-2 expression was blocked by combination with either actinomycin D or cycloheximide. In addition, Bcl-2 inhibition by HA14-1 led to increased cisplatin-induced apoptosis in KLE and HEC-1-A, whereas Bcl-2 overexpression in Ishikawa led to decreased cisplatin-induced apoptosis. Inhibition of protein kinase C (PKC) activity prevented cisplatin-dependant increase in Bcl-2 mRNA, and induced apoptosis in KLE cells. Furthermore, PKC inhibition was associated with decreased Akt and NF-κB activity. Cells stably expressing shRNA for Akt isoforms revealed that Akt2 was involved in cisplatin-dependant increase in Bcl-2 and apoptosis. Overexpression of Akt2 in Akt2-deficient cells led to increased Bcl-2 expression on cisplatin treatment. Our data suggest a novel regulation pathway of Bcl-2 by cisplatin, via the activation of PKC and Akt2, which has a profound impact on resistance to cisplatin-induced apoptosis in endometrial cancer cells.

Oxytocin increases invasive properties of endometrial cancer cells through phosphatidylinositol 3-kinase/AKT-dependent up-regulation of cyclooxygenase-1, -2, and X-linked inhibitor of apoptosis protein

Traditionally, oxytocin (OT) is well known to play a crucial role in the regulation of cyclic changes in the uterus, implantation of the embryo, and parturition. Recently, an additional role for OT has been identified in several types of cancer cells in which OT acts as a growth regulator. In endometrial cancer cells, OT is known to efficiently inhibit cellular proliferation. In the present study, we show that OT increases invasiveness of human endometrial carcinoma (HEC) cells, which are otherwise resistant to the growth-inhibiting effects of OT. Using pharmacological inhibitors, invasion assay, RNA interference, and immunofluorescence, we found that OT enhances the invasive properties of HEC cells through up-regulation of X-linked inhibitor of apoptosis protein (XIAP), matrix-metalloproteinase 2 (MMP2), and matrix-metalloproteinase 14 (MMP14). In addition, we show that OT-mediated invasion is both cyclooxygenase 1 (PTGS1) and cyclooxygenase-2 (PTGS2) dependent via the phosphatidylinositol 3-kinase/AKT (PIK3/AKT) pathway. PTGS2 knockdown by shRNA resulted in XIAP down-regulation. We also show that OT receptor is overexpressed in grade I to III endometrial cancer. Taken together, our results describe for the first time a novel role for OT in endometrial cancer cell invasion.

Bridging endometrial receptivity and implantation: network of hormones, cytokines, and growth factors

The prerequisite of successful implantation depends on achieving the appropriate embryo development to the blastocyst stage and at the same time the development of an endometrium that is receptive to the embryo. Implantation is a very intricate process, which is controlled by a number of complex molecules like hormones, cytokines, and growth factors and their cross talk. A network of these molecules plays a crucial role in preparing receptive endometrium and blastocyst. Furthermore, timely regulation of the expression of embryonic and maternal endometrial growth factors and cytokines plays a major role in determining the fate of embryo. Most of the existing data comes from animal studies due to ethical issues. In this study, we comprehend the data from both animal models and humans for better understanding of implantation and positive outcomes of pregnancy. The purpose of this review is to describe the potential roles of embryonic and uterine factors in implantation process such as prostaglandins, cyclooxygenases, leukemia inhibitory factor, interleukin (IL) 6, IL11, transforming growth factor-β, IGF, activins, NODAL, epidermal growth factor (EGF), and heparin binding-EGF. Understanding the function of these players will help us to address the reasons of implantation failure and infertility.

Abstract 1107: Transforming growth factor-beta (TGF-β) increases Par-4 expression via activation of Smad and NF-κB in endometrial cancer cells

Prostate apoptosis response-4 (Par-4) gene was originally identified in prostate cancer cells undergoing apoptosis. Further studies have shown that Par-4 selectively induces apoptosis in cancer cells without effecting normal cells. Recently it has been evidenced that Par-4 has a tumor suppressor role in endometrial cancer. We have previously demonstrated that TGF-β isoforms are expressed in endometrial tumors and determined cellular fate by regulating apoptosis through the activation of NF-κB. In the present study, we have investigated the mechanisms through which TGF-β isoforms regulate Par-4 expression in endometrial cancer cells. KLE and Hec-1-A endometrial cancer cell lines were used as model in this study. Transcript and protein levels were assessed by reverse transcriptase polymerase chain reaction (RT-PCR) and western blotting, respectively. The results revealed that both cell lines express TGF-β receptor I and receptor II. Blocking TGF-β signalling by neutralizing TGF-β antibody reduced endogenous Par-4 mRNA and protein levels. Exogenous treatment with all the TGF-β isoforms (10ng/ml) upregulated Par-4 mRNA and protein levels. Furthermore, there was increase in the levels of phosphorylated Smad2 and Smad3 in response to TGF-β treatment, thus indicating that Smad pathway was activated by TGF-β isoforms in these cells. However, there was no change in the protein levels of total Smad2/3. TGF-β treatment resulted in rapid phosphorylation of IκB-α with no effect on total IκB-α levels thus suggesting an activation, nuclear translocation and increase in transcriptional activity of NF-κB. Collectively, these results suggest that each TGF-β isoform induces Par-4 levels via the activation of Smad and NF-κB pathway in endometrial cancer cells. Since downregulation of Par-4 is a common event in different types of cancers, we suggest in these cases that TGF-β could be an interesting therapy and strategy to induce Par-4 and apoptosis in endometrial cancer cells.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1107. doi:10.1158/1538-7445.AM2011-1107

Abstract 2883: Vimentin downregulation modulates p53 levels and apoptosis in cancer cells

Vimentin, a mesenchymal-specific intermediate filament (IF) protein, is often express in epithelial cancers exhibiting a de-differentiated phenotype. Vimentin is associated with increased chemoresistance and metastatic potential. Chemoresistance is a multifactorial phenomenon which is a major cause of treatment failure in human cancer. Some IF proteins are known to promote resistance to stress-induced apoptosis, but the role of vimentin in this process is still unknown. In the present study, we investigate the role of vimentin in response to apoptosis-induced chemotherapeutic drugs in different epithelial carcinoma cell lines. Surprisingly, using siRNA, our results show that vimentin downregulation decreases caspase-3 and PARP cleavage induced by cisplatin, doxorubicin and TNFalpha. This unexpected result could be explained by the decrease of p53 protein levels in vimentin-downregulated cells. Indeed, we observed that vimentin knockdown decreases p53 levels in a proteasome-dependent manner and also modulates p53 ubiquitination. PI3K/Akt pathway is well known to promote chemoresistant phenotype in different cancers and Akt can also regulate p53 function. Our results show that vimentin-induced p53 decrease is associated with an increase of Akt phosphorylation. We propose that vimentin knockdown results in an increase of Akt activity which in turn regulates ubiquitination and proteasomal degradation of p53. We have recently showed that Akt isoforms regulates vimentin and keratins IF expression in epithelial cancer cells, suggesting that IF proteins are directly involved in PI3K/Akt signaling pathway. To our knowledge, these results represent the first indication that vimentin could regulate Akt activity and p53 levels in response to apoptosis-induced chemotherapeutic drugs. These results support the hypothesis that modulation of IF expression plays an active role in cancer progression and that vimentin could be a possible target for cancer therapy.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2883. doi:10.1158/1538-7445.AM2011-2883