Publications by authors named "Martin Shea"

13 Publications

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Therapeutic targeting of nemo-like kinase in primary and acquired endocrine-resistant breast cancer.

Clin Cancer Res 2021 Feb 4. Epub 2021 Feb 4.

Pathology, Baylor College of Medicine

Purpose: Endocrine resistance remains a major clinical challenge in estrogen-receptor (ER) positive breast cancer. Despite the encouraging results from clinical trials for the drugs targeting known survival signaling, relapse is still inevitable. There is an unmet need to discover new drug targets in the unknown escape pathways. Here we report Nemo-Like Kinase (NLK) as a new actionable kinase target that endows previously uncharacterized survival signaling in endocrine resistant breast cancer.

Experimental Design: The effects of NLK inhibition on the viability of endocrine resistant breast cancer cell lines were examined by MTS assay. The effect of VX-702 on NLK activity was verified by kinase assay. The modulation of ER and its coactivator SRC-3 by NLK were examined by immunoprecipitation, kinase assay, luciferase assay, and RNAseq. The therapeutic effects of VX-702 and Everolimus were tested on cell line- and patient-derived xenograft tumor models.

Results: NLK overexpression endow reduced endocrine responsiveness and is associated with worse outcome of tamoxifen-treated patients. Mechanistically, NLK may function at last in part via enhancing the phosphorylation of ERα and its key coactivator SRC-3 to modulate ERα transcriptional activity. Through interrogation of a kinase-profiling database, we uncovered and verified a highly selective dual p38/NLK inhibitor, VX-702. Co-administration of VX-702 with the mTOR inhibitor Everolimus demonstrated a significant therapeutic effect in cell line- and patient-derived xenograft tumor models of acquired or de novo endocrine resistance.

Conclusions: Together, this study reveals the potential of therapeutic modulation of NLK for the management of the endocrine-resistant breast cancers with active NLK signaling.
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http://dx.doi.org/10.1158/1078-0432.CCR-20-2961DOI Listing
February 2021

In vivo longitudinal imaging of RNA interference-induced endocrine therapy resistance in breast cancer.

J Biophotonics 2020 01 9;13(1):e201900180. Epub 2019 Oct 9.

Division of Molecular Imaging, Department of Radiology, Baylor College of Medicine, Houston, Texas.

Endocrine therapy resistance in breast cancer is a major obstacle in the treatment of patients with estrogen receptor-positive (ER+) tumors. Herein, we demonstrate the feasibility of longitudinal, noninvasive and semiquantitative in vivo molecular imaging of resistance to three endocrine therapies by using an inducible fluorescence-labeled short hairpin RNA (shRNA) system in orthotopic mice xenograft tumors. We employed a dual fluorescent doxycycline (Dox)-regulated lentiviral inducer system to transfect ER+ MCF7L breast cancer cells, with green fluorescent protein (GFP) expression as a marker of transfection and red fluorescent protein (RFP) expression as a surrogate marker of Dox-induced tumor suppressor phosphatase and tensin homolog deleted on chromosome 10 (PTEN) knockdown. Xenografted MCF7L tumor-bearing nude mice were randomized to therapies comprising estrogen deprivation, tamoxifen or an ER degrader (fulvestrant) and an estrogen-treated control group. Longitudinal imaging was performed by a home-built multispectral imaging system based on a cooled image intensified charge coupled device camera. The GFP signal, which corresponds to number of viable tumor cells, exhibited excellent correlation to caliper-measured tumor size (P < .05). RFP expression was substantially higher in mice exhibiting therapy resistance and strongly and significantly (P < 1e-7) correlated with the tumor size progression for the mice with shRNA-induced PTEN knockdown. PTEN loss was strongly correlated with resistance to estrogen deprivation, tamoxifen and fulvestrant therapies.
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http://dx.doi.org/10.1002/jbio.201900180DOI Listing
January 2020

Modulating absorption and charge transfer in bodipy-carbazole donor-acceptor dyads through molecular design.

Dalton Trans 2019 Jun;48(23):8488-8501

Department of Chemistry, Amherst College, Amherst, Massachusetts 01002, USA.

Three bodipy-based (BDP = 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) donor-acceptor dyads were designed and synthesized, and their ground-state and photophysical properties were systematically characterized. The electronic coupling between the BDP chromophore and an electron-donating carbazole (Carb) moiety was tuned by attachment via the meso and the beta positions on the BDP core, and through the use of various chemical linkers (phenyl and alkynyl) to afford mesoBDP-Carb, mesoBDP-phen-Carb, and betaBDP-alk-Carb. meso-Substituted dyads were found to retain ground-state absorption features of the unsubstituted BDP. However, variation of the linkage between the donor and acceptor moieties modulated the photophysical behavior of excited-state deactivation by controlling the rate of photoinduced internal charge transfer (ICT). The beta-substituted dyad dramatically tuned (red shifted) the absorption spectrum, while retaining desired features of the BDP, specifically stability and high extinction coefficients, however the ICT kinetics were accelerated compared to the meso-substituted dyads. Density functional theory (DFT) and time-dependent DFT (TDDFT) were carried out on the six potential dyads formed between BDP and Carb (attachment using the beta and meso positions for all three connections: direct, phenyl and alkynyl) to support the experimental observations. DFT and TDDFT showed molecular orbital density spread across the HOMO level only when attachment occurred through the beta position of BDP. In the meso-substituted BDP-Carb dyads, the molecular orbitals resembled those of the unsubstituted BDP. This work reveals several possible synthetic paradigms to tune photophysical properties with directed synthetic modifications and provides a mechanistic understanding of the ground- and excited- state behavior in these small-molecule donor-acceptor dyads.
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http://dx.doi.org/10.1039/c9dt00094aDOI Listing
June 2019

Anthracene-based azo dyes for photo-induced proton-coupled electron transfer.

Chem Commun (Camb) 2019 May 2;55(42):5874-5877. Epub 2019 May 2.

Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, USA.

Herein, we report a new donor-acceptor system for photo-induced proton-coupled electron transfer (PCET) that leverages an azo linkage as the proton-sensitive component and anthracene as a photo-trigger. Electrochemistry shows a change in the reduction potential with addition of acid. However, photochemistry is invariant to the absence or presence of acid. The anthracene and phenol/4-methoxyphenyl moieties of the azo dyes are highly conjugated, likely mitigating photo-induced charge transfer, despite sufficient driving force.
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http://dx.doi.org/10.1039/c9cc01206kDOI Listing
May 2019

The oral selective oestrogen receptor degrader (SERD) AZD9496 is comparable to fulvestrant in antagonising ER and circumventing endocrine resistance.

Br J Cancer 2019 02 17;120(3):331-339. Epub 2018 Dec 17.

Lester & Sue Smith Breast Center, Baylor College of Medicine, Houston, TX, 77030, USA.

Background: The oestrogen receptor (ER) is an important therapeutic target in ER-positive (ER+) breast cancer. The selective ER degrader (SERD), fulvestrant, is effective in patients with metastatic breast cancer, but its intramuscular route of administration and low bioavailability are major clinical limitations.

Methods: Here, we studied the pharmacology of a new oral SERD, AZD9496, in a panel of in vitro and in vivo endocrine-sensitive and -resistant breast cancer models.

Results: In endocrine-sensitive models, AZD9496 inhibited cell growth and blocked ER activity in the presence or absence of oestrogen. In vivo, in the presence of oestrogen, short-term AZD9496 treatment, like fulvestrant, resulted in tumour growth inhibition and reduced expression of ER-dependent genes. AZD9496 inhibited cell growth in oestrogen deprivation-resistant and tamoxifen-resistant cell lines and xenograft models that retain ER expression. AZD9496 effectively reduced ER levels and ER-induced transcription. Expression analysis of short-term treated tumours showed that AZD9496 potently inhibited classic oestrogen-induced gene transcription, while simultaneously increasing expression of genes negatively regulated by ER, including genes potentially involved in escape pathways of endocrine resistance.

Conclusions: These data suggest that AZD9496 is a potent anti-oestrogen that antagonises and degrades ER with anti-tumour activity in both endocrine-sensitive and endocrine-resistant models.
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http://dx.doi.org/10.1038/s41416-018-0354-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6353941PMC
February 2019

HER2 Reactivation through Acquisition of the HER2 L755S Mutation as a Mechanism of Acquired Resistance to HER2-targeted Therapy in HER2 Breast Cancer.

Clin Cancer Res 2017 Sep 9;23(17):5123-5134. Epub 2017 May 9.

Lester & Sue Smith Breast Center, Baylor College of Medicine, Houston, Texas.

Resistance to anti-HER2 therapies in HER2 breast cancer can occur through activation of alternative survival pathways or reactivation of the HER signaling network. Here we employed BT474 parental and treatment-resistant cell line models to investigate a mechanism by which HER2 breast cancer can reactivate the HER network under potent HER2-targeted therapies. Resistant derivatives to lapatinib (L), trastuzumab (T), or the combination (LR/TR/LTR) were developed independently from two independent estrogen receptor ER/HER2 BT474 cell lines (AZ/ATCC). Two derivatives resistant to the lapatinib-containing regimens (BT474/AZ-LR and BT474/ATCC-LTR lines) that showed HER2 reactivation at the time of resistance were subjected to massive parallel sequencing and compared with parental lines. Ectopic expression and mutant-specific siRNA interference were applied to analyze the mutation functionally. and experiments were performed to test alternative therapies for mutant HER2 inhibition. Genomic analyses revealed that the L755S mutation was the only common somatic mutation gained in the BT474/AZ-LR and BT474/ATCC-LTR lines. Ectopic expression of L755S induced acquired lapatinib resistance in the BT474/AZ, SK-BR-3, and AU565 parental cell lines. L755S-specific siRNA knockdown reversed the resistance in BT474/AZ-LR and BT474/ATCC-LTR lines. The HER1/2-irreversible inhibitors afatinib and neratinib substantially inhibited both resistant cell growth and the HER2 and downstream AKT/MAPK signaling driven by L755S and HER2 reactivation through acquisition of the L755S mutation was identified as a mechanism of acquired resistance to lapatinib-containing HER2-targeted therapy in preclinical HER2-amplified breast cancer models, which can be overcome by irreversible HER1/2 inhibitors. .
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http://dx.doi.org/10.1158/1078-0432.CCR-16-2191DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5762201PMC
September 2017

FOXA1 overexpression mediates endocrine resistance by altering the ER transcriptome and IL-8 expression in ER-positive breast cancer.

Proc Natl Acad Sci U S A 2016 10 6;113(43):E6600-E6609. Epub 2016 Oct 6.

Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030; Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX 77030; Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030; Department of Medicine, Baylor College of Medicine, Houston, TX 77030;

Forkhead box protein A1 (FOXA1) is a pioneer factor of estrogen receptor α (ER)-chromatin binding and function, yet its aberration in endocrine-resistant (Endo-R) breast cancer is unknown. Here, we report preclinical evidence for a role of FOXA1 in Endo-R breast cancer as well as evidence for its clinical significance. FOXA1 is gene-amplified and/or overexpressed in Endo-R derivatives of several breast cancer cell line models. Induced FOXA1 triggers oncogenic gene signatures and proteomic profiles highly associated with endocrine resistance. Integrated omics data reveal IL8 as one of the most perturbed genes regulated by FOXA1 and ER transcriptional reprogramming in Endo-R cells. IL-8 knockdown inhibits tamoxifen-resistant cell growth and invasion and partially attenuates the effect of overexpressed FOXA1. Our study highlights a role of FOXA1 via IL-8 signaling as a potential therapeutic target in FOXA1-overexpressing ER-positive tumors.
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http://dx.doi.org/10.1073/pnas.1612835113DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5087040PMC
October 2016

Overcoming endocrine resistance due to reduced PTEN levels in estrogen receptor-positive breast cancer by co-targeting mammalian target of rapamycin, protein kinase B, or mitogen-activated protein kinase kinase.

Breast Cancer Res 2014 Sep 11;16(5):430. Epub 2014 Sep 11.

Introduction: Activation of the phosphatidylinositol 3-kinase (PI3K) pathway in estrogen receptor α (ER)-positive breast cancer is associated with reduced ER expression and activity, luminal B subtype, and poor outcome. Phosphatase and tensin homolog (PTEN), a negative regulator of this pathway, is typically lost in ER-negative breast cancer. We set out to clarify the role of reduced PTEN levels in endocrine resistance, and to explore the combination of newly developed PI3K downstream kinase inhibitors to overcome this resistance.

Methods: Altered cellular signaling, gene expression, and endocrine sensitivity were determined in inducible PTEN-knockdown ER-positive/human epidermal growth factor receptor 2 (HER2)-negative breast cancer cell and/or xenograft models. Single or two-agent combinations of kinase inhibitors were examined to improve endocrine therapy.

Results: Moderate PTEN reduction was sufficient to enhance PI3K signaling, generate a gene signature associated with the luminal B subtype of breast cancer, and cause endocrine resistance in vitro and in vivo. The mammalian target of rapamycin (mTOR), protein kinase B (AKT), or mitogen-activated protein kinase kinase (MEK) inhibitors, alone or in combination, improved endocrine therapy, but the efficacy varied by PTEN levels, type of endocrine therapy, and the specific inhibitor(s). A single-agent AKT inhibitor combined with fulvestrant conferred superior efficacy in overcoming resistance, inducing apoptosis and tumor regression.

Conclusions: Moderate reduction in PTEN, without complete loss, can activate the PI3K pathway to cause endocrine resistance in ER-positive breast cancer, which can be overcome by combining endocrine therapy with inhibitors of the PI3K pathway. Our data suggests that the ER degrader fulvestrant, to block both ligand-dependent and -independent ER signaling, combined with an AKT inhibitor is an effective strategy to test in patients.
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http://dx.doi.org/10.1186/s13058-014-0430-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4303114PMC
September 2014

Sub-100nm gold nanomatryoshkas improve photo-thermal therapy efficacy in large and highly aggressive triple negative breast tumors.

J Control Release 2014 Oct 19;191:90-97. Epub 2014 Jul 19.

Division of Molecular Imaging, Department of Radiology, Baylor College of Medicine, Mail: BCM 360, One Baylor Plaza, Houston, TX 77030, United States.

There is an unmet need for efficient near-infrared photothermal transducers for the treatment of highly aggressive cancers and large tumors where the penetration of light can be substantially reduced, and the intra-tumoral nanoparticle transport is restricted due to the presence of hypoxic or necrotic regions. We report the performance advantages obtained by sub 100nm gold nanomatryushkas, comprising concentric gold-silica-gold layers compared to conventional ~150nm silica core gold nanoshells for photothermal therapy of triple negative breast cancer. We demonstrate that a 33% reduction in silica-core-gold-shell nanoparticle size, while retaining near-infrared plasmon resonance, and keeping the nanoparticle surface charge constant, results in a four to five fold tumor accumulation of nanoparticles following equal dose of injected gold for both sizes. The survival time of mice bearing large (>1000mm(3)) and highly aggressive triple negative breast tumors is doubled for the nanomatryushka treatment group under identical photo-thermal therapy conditions. The higher absorption cross-section of a nanomatryoshka results in a higher efficiency of photonic to thermal energy conversion and coupled with 4-5× accumulation within large tumors results in superior therapy efficacy.
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http://dx.doi.org/10.1016/j.jconrel.2014.07.038DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4156921PMC
October 2014

Au nanomatryoshkas as efficient near-infrared photothermal transducers for cancer treatment: benchmarking against nanoshells.

ACS Nano 2014 Jun 3;8(6):6372-81. Epub 2014 Jun 3.

Department of Chemistry, Rice University , 6100 Main Street, Houston, Texas 77005, United States.

Au nanoparticles with plasmon resonances in the near-infrared (NIR) region of the spectrum efficiently convert light into heat, a property useful for the photothermal ablation of cancerous tumors subsequent to nanoparticle uptake at the tumor site. A critical aspect of this process is nanoparticle size, which influences both tumor uptake and photothermal efficiency. Here, we report a direct comparative study of ∼90 nm diameter Au nanomatryoshkas (Au/SiO2/Au) and ∼150 nm diameter Au nanoshells for photothermal therapeutic efficacy in highly aggressive triple negative breast cancer (TNBC) tumors in mice. Au nanomatryoshkas are strong light absorbers with 77% absorption efficiency, while the nanoshells are weaker absorbers with only 15% absorption efficiency. After an intravenous injection of Au nanomatryoshkas followed by a single NIR laser dose of 2 W/cm(2) for 5 min, 83% of the TNBC tumor-bearing mice appeared healthy and tumor free >60 days later, while only 33% of mice treated with nanoshells survived the same period. The smaller size and larger absorption cross section of Au nanomatryoshkas combine to make this nanoparticle more effective than Au nanoshells for photothermal cancer therapy.
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http://dx.doi.org/10.1021/nn501871dDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4076033PMC
June 2014

An epigenomic approach to therapy for tamoxifen-resistant breast cancer.

Cell Res 2014 Jul 30;24(7):809-19. Epub 2014 May 30.

1] Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA [2] Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX 77030, USA.

Tamoxifen has been a frontline treatment for estrogen receptor alpha (ERα)-positive breast tumors in premenopausal women. However, resistance to tamoxifen occurs in many patients. ER still plays a critical role in the growth of breast cancer cells with acquired tamoxifen resistance, suggesting that ERα remains a valid target for treatment of tamoxifen-resistant (Tam-R) breast cancer. In an effort to identify novel regulators of ERα signaling, through a small-scale siRNA screen against histone methyl modifiers, we found WHSC1, a histone H3K36 methyltransferase, as a positive regulator of ERα signaling in breast cancer cells. We demonstrated that WHSC1 is recruited to the ERα gene by the BET protein BRD3/4, and facilitates ERα gene expression. The small-molecule BET protein inhibitor JQ1 potently suppressed the classic ERα signaling pathway and the growth of Tam-R breast cancer cells in culture. Using a Tam-R breast cancer xenograft mouse model, we demonstrated in vivo anti-breast cancer activity by JQ1 and a strong long-lasting effect of combination therapy with JQ1 and the ER degrader fulvestrant. Taken together, we provide evidence that the epigenomic proteins BRD3/4 and WHSC1 are essential regulators of estrogen receptor signaling and are novel therapeutic targets for treatment of Tam-R breast cancer.
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http://dx.doi.org/10.1038/cr.2014.71DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4085766PMC
July 2014

Epigenetic reprogramming of HOXC10 in endocrine-resistant breast cancer.

Sci Transl Med 2014 Mar;6(229):229ra41

Graduate Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, TX 77030, USA.

Resistance to aromatase inhibitors (AIs) is a major clinical problem in the treatment of estrogen receptor (ER)-positive breast cancer. In two breast cancer cell line models of AI resistance, we identified widespread DNA hyper- and hypomethylation, with enrichment for promoter hypermethylation of developmental genes. For the homeobox gene HOXC10, methylation occurred in a CpG shore, which overlapped with a functional ER binding site, causing repression of HOXC10 expression. Although short-term blockade of ER signaling caused relief of HOXC10 repression in both cell lines and breast tumors, it also resulted in concurrent recruitment of EZH2 and increased H3K27me3, ultimately transitioning to increased DNA methylation and silencing of HOXC10. Reduced HOXC10 in vitro and in xenografts resulted in decreased apoptosis and caused antiestrogen resistance. Supporting this, we used paired primary and metastatic breast cancer specimens to show that HOXC10 was reduced in tumors that recurred during AI treatment. We propose a model in which estrogen represses apoptotic and growth-inhibitory genes such as HOXC10, contributing to tumor survival, whereas AIs induce these genes to cause apoptosis and therapeutic benefit, but long-term AI treatment results in permanent repression of these genes via methylation and confers resistance. Therapies aimed at inhibiting AI-induced histone and DNA methylation may be beneficial in blocking or delaying AI resistance.
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http://dx.doi.org/10.1126/scitranslmed.3008326DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4277862PMC
March 2014

Therapeutic potential of the dual EGFR/HER2 inhibitor AZD8931 in circumventing endocrine resistance.

Breast Cancer Res Treat 2014 Apr 20;144(2):263-72. Epub 2014 Feb 20.

Lester and Sue Smith Breast Center and Dan L Duncan Cancer Center, Baylor College of Medicine, One Baylor Plaza, BCM:600, Houston, TX, 77030, USA.

Modest up-regulation of either HER-ligands or receptors has been implicated in acquired endocrine resistance. AZD8931, a dual tyrosine kinase inhibitor (TKI) of epithelial growth factor receptor (EGFR)/HER2, has been shown to more effectively block ligand-dependent HER signaling than the HER TKIs lapatinib or gefitinib. We therefore examined the effect of AZD8931 in ER-positive/HER2-negative breast cancer cells with acquired resistance to tamoxifen, where there is ligand up-regulation associated with HER pathway activation. RNA-seq ligand profiling and levels of HER receptors and signaling by western blotting were conducted in ER+ MCF7 and T47D parental cells and their Tam-resistant derivatives (TamRes). In vitro cell growth and apoptosis and HER ligand-stimulated signaling were measured in response to endocrine and HER TKIs. For studies in vivo, transplantable MCF7/TamRes xenografts were treated with tamoxifen or fulvestrant, either alone or in combination with AZD8931. AZD8931 only minimally enhanced endocrine sensitivity in MCF7 parental cells, but showed a greater effect in the T47D parental model. AZD8931 combined with either tamoxifen or fulvestrant inhibited cell growth more than lapatinib in T47D TamRes cells, and was also significantly, though modestly, more potent in MCF7 TamRes cells. In both TamRes models, AZD8931 significantly inhibited cell proliferation and induced apoptosis. Under ligand-stimulated conditions, AZD8931 more potently inhibited HER signaling than lapatinib or gefitinib. AZD8931 also significantly delayed the growth of MCF7 TamRes xenografts in the presence of tamoxifen or fulvestrant. The strongest inhibition was achieved with a fulvestrant and AZD8931 combination, though no tumor regression was observed. This study provides evidence that AZD8931 has greater inhibitory efficacy in tamoxifen-resistant settings than in an endocrine therapy naïve setting. The absence of tumor regression, however, suggests that additional escape pathways contribute to resistant growth and will need to be targeted to fully circumvent tamoxifen resistance.
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http://dx.doi.org/10.1007/s10549-014-2878-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4030601PMC
April 2014