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M.P. Barr
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MINI 08 - Prognostic/Predictive Biomarkers (ID 106)
- Event: WCLC 2015
- Type: Mini Oral
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 1
- Moderators:T.E. Stinchcombe, N. Pavlakis
- Coordinates: 9/07/2015, 16:45 - 18:15, Mile High Ballroom 4a-4f
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MINI08.08 - VEGF-Mediated Cell Survival in NSCLC: Implications for Epigenetic Targeting of VEGF Receptors as a Therapeutic Approach (ID 2721)
17:35 - 17:40 | Author(s): M.P. Barr
- Abstract
- Presentation
Background:
We have recently shown that VEGF, at least in part, is an autocrine growth factor for NSCLC cells, mediating its survival effects via VEGFR2 (KDR) in addition to the more novel receptor, Neuropilin-1 (Barr et al., Mol Cancer, 2015). In this study, we evaluated the potential therapeutic utility of histone deacetylase (HDAC) inhibitors in targeting the VEGF-VEGFR signalling axis in non-small cell lung cancer (NSCLC) cells.
Methods:
The effect of the HDAC inhibitor, Trichostatin-A (TSA) on modulating the expression of the VEGF receptors, VEGFR1, VEGFR2, NP1 and NP2, in A549 and SKMES-1 cells was examined and validated at the mRNA level and protein levels using RT-PCR and Western blot analysis. Gene expression was further validated by quantitative real-time PCR. To investigate the effect of TSA on the viability of NSCLC cells, these were treated with increasing concentrations of TSA (2.5 ng/ml-250 ng/ml) for 24h. Cell proliferation and apoptosis was measured by BrdU and Annexin V/PI (FACS), respectively. VEGF protein secretion in response to TSA was assessed in conditioned media from lung tumour cells by ELISA. To determine if the effects of TSA on VEGFR receptors were mediated through immediate to early responses, cells were pre-treated with cycloheximide (10 µg/ml) for 2 h followed by treatment with TSA (250 ng/ml) for 24 h. To confirm whether the observed effects of HDAC inhibition by TSA were due to increased histone hyperacetylation at the VEGFR1 and VEGFR2 gene promoters, chromatin immunoprecipitation (ChIP) analysis was carried out following treatment with TSA.
Results:
NP1 and NP2 mRNA levels were decreased in both A549 and SKMES-1 lung cancer cells in response to TSA and induced the expression of VEGFR1 and VEGFR2 at higher concentrations. TSA however, had no effect on VEGF mRNA expression. Critically, the effect of TSA was more marked at the protein level, with complete loss of Neuropilin-1 protein. HDAC inhibition resulted in a significant decrease in the viability of A549 and SKMES-1 cells in a dose-dependent fashion. While TSA induced significant apoptosis of both lung tumour cell lines, VEGF was unable to rescue cells from TSA-induced cell death. VEGF secretion was significantly decreased in both cell lines. Treatment with cycloheximide was unable to abrogate the TSA-mediated increase in the VEGF receptors examined, indicating that de novo protein synthesis is not required for these observed effects, but may be due to direct effects at the promoter level. Direct histone acetylation of histones H3 and H4 was observed, indicating an increase in histone hyperacetylation of VEGFR1 and VEGR2 promoters. A significant trend in the modulation of the VEGF receptors similar to that seen in response to TSA was shown when treated with Vorinostat (SAHA).
Conclusion:
Epigenetic targeting of the Neuropilin receptors may offer an effective treatment for NSCLC patients in the clinical setting. The possibility of novel targeted agents decreasing the levels, or function, of tumour VEGF receptors, in particular NP1, may lead to more successful treatments and prolonged overall survival in these patients.
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MINI 34 - RNA and miRNA (ID 162)
- Event: WCLC 2015
- Type: Mini Oral
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 1
- Moderators:C. Mascaux, L.(. Wang
- Coordinates: 9/09/2015, 18:30 - 20:00, 205+207
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MINI34.07 - A Novel microRNA Signature Associated with Cisplatin Resistance in NSCLC (ID 2709)
19:05 - 19:10 | Author(s): M.P. Barr
- Abstract
- Presentation
Background:
MicroRNAs (miRNAs) are an abundant class of small non-coding RNAs that range in size from 19 to 25 nucleotides. Alteration in miRNA expression can cause them to act as either tumour suppressor or oncogenes. They have also been shown to regulate a number of processes involved in tumour biology such as metastasis, invasion and angiogenesis. More recently, miRNAs have been linked to chemo- and radio-resistance in many solid tumours, including lung cancer.
Methods:
An isogenic model of cisplatin resistance was established by chronically exposing a panel of NSCLC cell lines (MOR, H460, A549, SKMES-1, H1299) to cisplatin for 12 months, generating cisplatin resistant (CisR) sublines from their corresponding age-matched parental (PT) cells. MicroRNA expression profiling was carried out using 7th generation miRCURY LNA™ microRNA arrays consisting of 1,919 miRNAs (Exiqon). MicroRNAs that were significantly increased in CisR sublines were inhibited using antagomirs (Exiqon), while those that were significantly decreased were over-expressed using pre-miRs (Ambion). Functional studies examining clonogenic survival ability, proliferation (BrdU) and apoptosis (Annexin V/PI) were subsequently carried out in the presence or absence of cisplatin. To examine the translational relevance of these microRNAs, their expression was further examined in a cohort of pre-treatment matched normal and tumour lung tissues from NSCLC patients of different histological subtypes. Validation of this miRNA signature is currently being investigated in serum samples from this same cohort of patients and normal controls.
Results:
MicroRNA profiling analysis identified ten miRNAs which were significantly altered between parental and corresponding cisplatin resistant lung cancer cell lines. Validation of these miRNAs by real-time PCR (qPCR) identified a specific 5-miR signature that was significantly altered in CisR cells relative to their parental counterparts. Modification of these microRNAs altered the response of resistant cells to the cytotoxic effects of cisplatin and decreased the clonogenic survival of CisR cells when treated with increasing doses of cisplatin (0.1µM-10μM). Significant differential expression was found between normal and tumour tissues across each histological subtype, highlighting the potential use of these microRNAs as markers of response to cisplatin therapy in NSCLC patients. Three miRNAs (miR-A, B, C) belonging to the same family were significantly altered in tumour lung tissue of adenocarcinoma and squamous cell histology compared to matched normal lung tissue. MicroRNA-D expression was significantly altered in squamous cell carcinomas while miR-E was differentially expressed in adenocarcinomas only. Data relating to the expression of this novel signature in the circulation of our NSCLC patient cohort and normal controls will be presented at WCLC 2015.
Conclusion:
We have identified and validated a novel miRNA signature associated with cisplatin resistance in a panel of cisplatin resistant cell lines and in patient lung tumours. Genetic manipulation of these specific miRNAs in vitro altered the cisplatin resistant cell response to the cytotoxic effects of cisplatin chemotherapy. The data obtained from this study may provide a basis for the potential development of a companion diagnostic for lung cancer patients who are most likely to benefit, or not, from cisplatin chemotherapy.
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ORAL 42 - Drug Resistance (ID 160)
- Event: WCLC 2015
- Type: Oral Session
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 1
- Moderators:R.C. Doebele, J.V. DeGregori
- Coordinates: 9/09/2015, 18:30 - 20:00, Mile High Ballroom 4a-4f
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ORAL42.06 - Cancer Stem Cells: Targeting Aldehyde Dehydrogenase 1 (ALDH1) as a Novel Strategy in Cisplatin Resistant Non-Small Cell Lung Cancer? (ID 2724)
19:24 - 19:35 | Author(s): M.P. Barr
- Abstract
- Presentation
Background:
Cisplatin is the backbone of chemotherapeutic treatment of lung cancer. Unfortunately the development of resistance has become a major challenge in the use of this cytotoxic drug. Understanding the mechanisms underlying this resistance phenotype may potentially result in the development of novel agents that may enhance the sensitivity of cisplatin chemotherapy in the clinical setting. The root of this resistance is hypothesized to be due to the presence of a rare cancer stem cell (CSC) population within the tumour that can reform a heterogenic tumour, resulting in recurrence and resistance following cisplatin chemotherapy.
Methods:
An isogenic model of cisplatin resistance was established by chronically exposing a panel of NSCLC cell lines (H460, SKMES, H1299) to cisplatin for 12months, thereby creating cisplatin resistant (CisR) sublines and their corresponding age-matched parental (PT) cells. To identify a CSC population within the resistant sublines, PT and CisR cell lines representing the three classifications of NSCLC were stained for ALDH1 using the Aldefluor kit (Stemcell Technologies). ALDH1 positive (+ve) and negative (-ve) subpopulations were isolated and their functional characteristics assessed. Proliferation and survival of ALDH1+ve fractions in response to cisplatin was assessed using BrdU and clonogenic survival assays relative to ALDH1-ve cells. ALDH1 subpopulations were examined for asymmetric division and expression of the human embryonic stem cell markers Nanog, Oct-4, Sox-2, Klf-4 and c-Myc and CD133. To confirm that this ALDH1+ve population is associated with cisplatin treatment, PT and CisR cells were chronically exposed to high dose cisplatin for 2 weeks and stained for ALDH1 and re-assessed for stemness qualities. Apoptosis and clonogenic survival of PT and CisR cells was assessed in response to selective inhibition of ALDH1 using diethylaminobenzaldehyde (DEAB) in combination with cisplatin. Xenograft studies in NOD/SCID mice are currently under investigation to examine the tumourigenic potential of isolated subpopulations of ALDH1.
Results:
A significant ALDH1+ve population was detected in CisR sublines, but not in their PT counterparts. Characterisation of the ALDH1+ve subpopulation confirmed enhanced expression of stemness markers, increased resistance and clonogenic survival in response to cisplatin compared to their ALDH1-ve counterparts, and the ability to asymmetrically divide. Chronic cisplatin treatment of the PT cell lines for 2 weeks increased resistance to cisplatin, increased stemness marker expression and induced the emergence of an ALDH1+ve population. Chronic high dose cisplatin treatment significantly expanded the ALDH1+ve population in the CisR cell lines. Importantly, inhibition of ALDH1 activity, with DEAB, decreased the mean cell viability, clonogenic survival capacity and increased cisplatin-induced apoptosis of the CisR cells when used in combination with cisplatin, an effect not seen in the PT cells.
Conclusion:
In this study, we have demonstrated the existence of a putative CSC population within our model of isogenic cisplatin resistant cell lines and suggest a role for ALDH1 inhibition as a potential therapeutic strategy in re-sensitizing chemoresistant lung cancer cells to the cytotoxic effects of cisplatin. Further studies will focus on re-purposing of FDA-approved ALDH1 inhibitor, Disulfiram (Antabuse), used in the treatment of chronic alcoholism as a potential combination therapy to prime chemoresistant cells to cisplatin.
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P1.04 - Poster Session/ Biology, Pathology, and Molecular Testing (ID 233)
- Event: WCLC 2015
- Type: Poster
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 1
- Moderators:
- Coordinates: 9/07/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)
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P1.04-088 - Lung Cancer Cells Can Alter the Behaviour of Normal Bronchial Epithelial Cells Through Multiple Mechanisms (ID 1312)
09:30 - 09:30 | Author(s): M.P. Barr
- Abstract
Background:
Lung cancer is one of the most heterogeneous of all solid cancers. This may in part be due to hi-jacking and additional bystander affects that are exerted on the normal lung cell population by the cancer cells. A number of pathways may be stimulated through soluble factors or effector filled vesicles such as exosomes secreted by cancer cells. The aim of this project was to evaluate the effects of non-small cell lung cancer (NSCLC) cells on an immortalised normal bronchial epithelial cell line.
Methods:
A normal bronchial epithelial cell line (HBEC4) was exposed to adenocarcinoma, large cell and squamous NSCLC cell lines and a number of phenotypic and genotypic characterisations were undertaken. These included cellular proliferation (BrdU ELISA), gene (RT-PCR) and miRNA expression screening (Nanostring). The effect of cancer exosome fractions was also determined.
Results:
Exposure to various subtypes of NSCLC significantly increased the cellular proliferation rate of the immortalised cell line in a number of models. Expression of a number of miRNAs were altered in the normal cells pre- and post exposure to the cancer cells. Various stem cell factor markers (KLF4, Oct, c-myc) were also significantly changed at the mRNA level. In addition, exosome fractions altered the behaviour of the normal cell line, likewise stimulating cell proliferation.
Conclusion:
Lung cancer cells may influence normal cell behaviour in both a direct and indirect manner using multiple mechanisms. Normal bronchial epithelial cells with stem like features may be induced to proliferate and behave in a malignant manner. This, akin to Hodgkin’s lymphoma, may contribute significantly to the composition of the tumour. Furthermore this observation may contribute to the heterogeneity of lung cancer tumours and affect treatment response. Ongoing studies are evaluating these effects in novel 2D and 3D culture systems.
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P2.04 - Poster Session/ Biology, Pathology, and Molecular Testing (ID 234)
- Event: WCLC 2015
- Type: Poster
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 4
- Moderators:
- Coordinates: 9/08/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)
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P2.04-057 - Targeting PIM Kinase in NSCLC (ID 933)
09:30 - 09:30 | Author(s): M.P. Barr
- Abstract
Background:
PIM proteins belong to a family of serine/threonine kinases composed of 3 isoforms, PIM1, PIM2 and PIM3, that play a key role in cell cycle regulation, have potent anti-apoptotic activity and play a role in the homing and migration of metastatic cells. Furthermore, PIM kinases have also been shown to be activated in response to Akt pathway inhibition, indicating a role in adaptive responses to inhibition of this pathway potentially leading to treatment resistance. Thus, there is a strong rationale for combining PIM kinase inhibition with inhibition of the Akt pathway (i.e., inhibitors of EGFR, PI3K, Akt and mTOR). PIM kinase has been recognised as a therapeutic target particularly in haematological malignancies however the role of PIM kinases in solid tumours and NSCLC in particular are less well characterised. This study is the first to elucidate the expression of all 3 PIM isoforms in NSCLC cell lines and patient tumours as well as to examine the effect of Inflection Bioscience Ltd novel dual PI3K/PIM kinase (IBL-202) and triple PI3K/mTOR/PIM kinase (IBL-301) targeted therapies in-vitro and in-vivo.
Methods:
PIM 1/2/3 protein expression was quantified by western blot analysis in a panel of NSCLC cell lines and 40 matched normal/tumour tissues from NSCLC patients (20 adenocarcinoma and 20 squamous cell carcinoma). PIM kinase expression was correlated to patient clinicopathological characteristics and survival data. The effectiveness of IBL-202 and IBL-301 on proliferation and apoptosis in NSCLC cell lines were examined by BrdU and Annexin V/PI FACS analysis, respectively. A head-to-head in-vivo study of IBL-202 vs. IBL-301 in xenograft nude mice formed using H1975 cells is ongoing.
Results:
All 3 isoforms of PIM kinase are highly expressed across a panel of NSCLC cell lines. PIM kinase is expressed in ~ 90% of NSCLC tumour tissues across all stages of the disease. IBL-202 and IBL-301 induced apoptosis and decreased cell proliferation in NSCLC cell lines at micromolar concentrations in-vitro. The in-vivo study is ongoing and results will be presented.
Conclusion:
PIM kinase is a promising new therapeutic target for the treatment of NSCLC patients. Dual PI3K/PIM kinase (IBL-202) and triple PI3K/mTOR/PIM kinase (IBL-301) targeted therapies have demonstrated pro-apoptotic and anti-proliferative activity in-vitro and in-vivo and should be considered in the treatment of NSCLC patients.
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P2.04-099 - Differential Regulation of DNA Repair Genes in Cisplatin Resistant Non-Small Cell Lung Cancer Cells (ID 2746)
09:30 - 09:30 | Author(s): M.P. Barr
- Abstract
Background:
In the absence of specific treatable mutations, cisplatin-based doublet chemotherapy remains the gold standard treatment for NSCLC patients. However, its clinical efficacy is hindered in many patients due to both intrinsic and acquired resistance to this drug. Alterations in the DNA repair capacity of damaged cells is now recognised as an important factor in mediating this phenomenon. DNA repair is therefore a vital target to improving cancer therapy and overcoming resistance of tumour cells to DNA damaging agents currently used in the treatment of NSCLC patients.
Methods:
DNA Repair Pathway RT[2 ]Profiler Arrays were used to elucidate the key DNA repair genes implicated in cisplatin resistant NSCLC cells using cisplatin resistant (CisR) and corresponding parental (PT) H460 NSCLC cells previously established in our laboratory. The regulation of the trans-activation of p53 in response to DNA damage was studied by examining protein accumulation, post-translational modifications (p53[Ser15]) and whether depletion of the novel DNA repair protein, hSSB1, affects the regulation of p53 in response to cisplatin. The repair of cisplatin-induced double strand breaks (DSBs) was examined by immunofluorescence imaging of γH2AX foci. Expression of p53[Ser15] (phosphorylated & total) in addition to hSSB1 was also assessed by HCA and Western blot analysis.
Results:
We identified a number of critical DNA repair genes that were differentially regulated between parental and cisplatin resistant NSCLC cells, some of which are known to be implicated in the nucleotide and mismatch repair pathways. H2AX was shown to be a reliable and specific marker of DNA double strand DNA breaks induced by platinum agents such as cisplatin. Cisplatin induced the translocation of p53 from the cytoplasmic compartment of H460 PT cells to the nuclear compartment, while significant levels of p53 were retained within the cytoplasmic compartment of CisR cells. Using both HCS and Western blot analysis, hSSB1 protein was undetectable.
Conclusion:
To date, despite reports that differential expression of components of the various DNA repair pathways correlate with response to cisplatin, translation of such findings in the clinical setting are warranted. The identification of alterations in specific proteins and pathways that contribute to these unique DNA repair pathways in cisplatin resistant cancer cells may potentially lead to a renewed interest in the development of rational novel therapies for cisplatin resistant cancers, in particular, lung cancer.
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P2.04-102 - Targeting Inflammatory Mediators to Overcome Intrinsic and Acquired Cisplatin Resistance in Non-Small Cell Lung Cancer (ID 1314)
09:30 - 09:30 | Author(s): M.P. Barr
- Abstract
Background:
Cisplatin based doublet-chemotherapy is commonly used in non-small cell lung cancer (NSCLC) treatment with an initial objective response rate of 40-50%. However, intrinsic and acquired chemo-resistance constitutes a major clinical obstacle. The mechanisms of resistance have yet to be fully understood. We have previously demonstrated that NF-κB levels are elevated in cisplatin resistant cells (CisR) and that the use of an NF-κB inhibitor, DHMEQ, resulted in greater CisR cell death. The goal of this project is to elucidate the mechanistic links between NF-κB regulated pathways and the development of cisplatin resistant NSCLC.
Methods:
The expression of NF-κB mediators and immune regulators were assessed in an isogenic NSCLC cell line model of cisplatin resistance using qPCR arrays (252 genes). A number of targets were identified and validated using PCR. The effect of drug combinations (Cisplatin and DHMEQ) was also determined. Comet assays (DNA damage) were also performed to determine the effect of DHMEQ alone or in combination with irradiation (6 Gy).
Results:
Various chemokines and their receptors were elevated in cisplatin resistant (CisR) cells compared with cisplatin sensitive (PT). In addition, a number of key TLRs and regulators of the innate immune pathway were altered. DHMEQ enhanced cellular sensitivity to cisplatin in both PT and CisR cell lines (p<0.05). This drug also overcame the chemo-protective effect of a number of chemokines and enhanced irradiation induced DNA damage. An animal study will commence shortly using DHMEQ alone and in combination with cisplatin.
Conclusion:
Immune-modulators such as DHMEQ may be a novel viable option in addressing inflammatory mediated acquired and intrinsic NSCLC chemo-resistance. In addition, immune regulators identified in this project may provide innovative targets for immuno-oncology therapy.
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P2.04-109 - Epithelial-To-Mesenchymal Transition (EMT) and Acquired Resistance to PI3K-mTOR Inhibition in NSCLC (ID 934)
09:30 - 09:30 | Author(s): M.P. Barr
- Abstract
Background:
The PI3K-Akt-mTOR pathway regulates cell growth and proliferation and is often dysregulated in NSCLC, making it an attractive therapeutic target in this setting. GDC-0980 is a selective dual inhibitor of PI3K and mTOR, which is currently in Phase II clinical trials for solid tumours. As with all targeted therapies, acquired resistance to GDC-0980 is anticipated to be a major hurdle in the success of this drug. The aims of this project are to (i) elucidate the frequency of PIK3CA mutations in an Irish cohort of NSCLC patients and (ii) develop and characterise three cell line models of resistance to GDC-0980, each representing a different molecular subtype of NSCLC, in order to identify biomarkers of response/resistance to the drug that may dictate beneficial treatment strategies.
Methods:
DNA was extracted from 250 NSCLC patient tissue samples, and screened for 547 clinically relevant mutations in 46 genes using the Sequenom platform. H460, A549, and H1975 cells were cultured in GDC-0980 at IC50 concentrations over a period of several months, along with matched ‘parent’ cell lines. Development of resistance was assessed by monthly BrdU proliferation assays. Cell growth patterns were compared across the sensitive and resistant cell lines in real time using the xCELLigence platform. Cell lines were then interrogated for alterations in DNA (Sequenom), mRNA (SABiosciences arrays profiling expression of >150 genes), miRNA (Exiqon expression profiling of 2100 miRNAs) and protein (R&D Phospho Kinase array expression profiling of 43 kinases and 2 associated total proteins, PTMScan[®] Ubiquitin Remnant Motif (K-ε-GG) Kit from CST and Western blot analysis).
Results:
PIK3CA mutations occur in ~5% adenocarcinomas & 12% squamous cell carcinomas. H1975 cells (PIK3CA mutant and activated pAkt (Ser473/Thr308), pmTOR, pS6R) were most sensitive to GDC-0980, however they were the first to develop resistance to the drug. Results obtained from xCELLigence studies identified H1975 resistant (H1975R) cells as having the highest cell index out of all parent and resistant cell lines after 100 hours of cell growth, suggesting that these are the most aggressive cells. Initially a 33 miRNA signature was identified contrasting H1975P and H1975R. qPCR validation of miR-205 (a regulator of EMT) identified expression in H1975P cells but miR-205 was undetectable in H1975R cells. mRNA expression of Zeb1 & Zeb2 (direct targets of miR-205) were increased in H1975R cells compared to H1975P cells. 1,200 proteins were found to be differentially expressed between H1975P and H1975R cells. Increased expression of EMT proteins vimentin, desmin and filamin was detected in H1975R cells (p < 0.05, fold change >2). Vimentin overexpression in H1975R cells was confirmed by western blot analyis. Activation of EMT was identified as one potential mechanism of resistance to GDC-0980 in H1975R cells.
Conclusion:
The PI3K-mTOR pathway is frequently mutated in NSCLC, in particular squamous cell carcinoma, making it an ideal therapeutic target. Acquired resistance to GDC-0980 developed rapidly in NSCLC cell lines, (4-6 months) and correlates to the induction of EMT. Further elucidation of EMT regulation is under investigation and is crucial to the design of improved treatment protocols.
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P3.08 - Poster Session/ Thymoma, Mesothelioma and Other Thoracic Malignancies (ID 226)
- Event: WCLC 2015
- Type: Poster
- Track: Thymoma, Mesothelioma and Other Thoracic Malignancies
- Presentations: 1
- Moderators:
- Coordinates: 9/09/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)
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P3.08-008 - Tip60 (KAT5) May Be a Candidate for Therapeutic Targeting in Malignant Pleural Mesothelioma (ID 1760)
09:30 - 09:30 | Author(s): M.P. Barr
- Abstract
Background:
Malignant pleural mesothelioma (MPM) is a rare aggressive cancer of the pleura. The most well established risk factor for this disease is exposure to asbestos. The current standard of care for patients suffering from MPM is a combination of cisplatin and pemetrexed (or alternatively cisplatin and raltitrexed). Most patients however, die within 24 months of diagnosis. New therapies are therefore urgently required for this disease. KAT5 (also known as Tip60) is the catalytic subunit of the NuA4 histone acetyltransferase complex which is involved in transcriptional activation of select genes. This complex may be required for the activation of transcriptional programs associated with oncogene and proto-oncogene mediated growth induction, tumor suppressor mediated growth arrest and replicative senescence, apoptosis, and DNA repair. KAT5 has also been linked with the development of cisplatin resistance. KAT5 may therefore be a significant element in MPM with respect to responses to cisplatin based therapy and could represent a novel candidate target for intervention.
Methods:
KAT5 has 4 variant mRNAs. Primers were designed to distinguish between all variants, and a panel of MPM cell lines was screened for KAT5 expression by RT-PCR. Levels of KAT5 were subsequently examined in a cohort of snap-frozen patient samples isolated at surgery comprising benign, epithelial, biphasic, and sarcomatoid histologies by RT-PCR. The effects of a small molecule inhibitor of KAT5 (MG-149) on cellular proliferation were examined.
Results:
Semi-quantitative densitometric analysis showed that the expression of KAT5 is dramatically increased in MPM for all mRNA variants. When separated according to histological subtype, significant differences were also observed between the various histologies. A small molecule inhibitor of KAT5 exists and treatment of cells with this small molecule inhibitor (MG-149) resulted in a significant inhibition of cellular proliferation (p < 0.001) in the NCI-H226 cell line. We continue to assess this compound by other methodologies to confirm its potential utility in the treatment of MPM.
Conclusion:
KAT5, a lysine acetyltransferase associated with cisplatin resistance in cancer is significantly altered in MPM. A small molecule inhibitor of this protein shows significant anti-proliferative effects in MPM cell lines. Targeting this protein may have important future implications for the management of MPM.
