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A novel naproxen derivative capable of displaying anti-cancer and anti-migratory properties against human breast cancer cells
© Deb et al.; licensee BioMed Central Ltd. 2014
Received: 18 February 2014
Accepted: 30 July 2014
Published: 7 August 2014
Increasingly, the role of chronic inflammation and its mediators in tumor generation and progression is gaining importance in the field of cancer research. In this context, candidature of non steroidal anti-inflammatory drugs (NSAIDs) as potential anti-tumor therapeutic agent is being evaluated globally. In the present study we have evaluated the anti-cancer effect of a series of newly synthesized naproxen derivatives on human breast cancer cell lines.
MCF-7 (poorly invasive) and MDA-MB-231 (highly invasive) cells were treated with different concentrations of naproxen sodium and its derivatives in vitro, and the underlying mechanism of action was monitored by employing studies related to induction of apoptosis, activation of caspases, cell-cycle progression, synthesis of PGE2 and cellular migration.
After a preliminary screening using MCF-7 and MDA-MB-231 cells, it was evident that naproxen derivative 4 has a better killing property compared to its parent compound naproxen sodium (NS). On further investigation, it was apparent that the observed growth inhibitory activity on MDA-MB-231 cells after treatment with 4, was not due to cell cycle arrest but due to an early induction of apoptosis and subsequent induction of caspases 3 and 9. Derivative 4 could also inhibit COX activity in MDA-MB-231 cells as evidenced by reduction in prostaglandin E2 secretion. Moreover, 4 was capable of delaying the overall migration rate of MDA-MB-231 cells in vitro.
In this study we report that a naproxen-derivative (4) has powerful anti-inflammatory and anti-tumor properties as it induces appreciable amount of apoptosis in breast cancer cell line, and can also delay migration of cancer cells (MDA-MB-231) which would in turn delay cancer cell invasion and formation of secondary tumours in primary breast cancer patients. Thus, we propose that 4 is worthy of further investigation due to its potential as a therapeutic agent in anti-tumor treatment regimen.
KeywordsMCF-7 MDA-MB-231 MTT assay Apoptosis Inflammation Metastasis
The functional relationship between inflammation and cancer was first brought into picture in 1863, when Rudolf Virchow hypothesized that cancer originates at the site of chronic inflammation . Since then a vast number of studies have emphasized on the role of chronic inflammation in tumorogenesis  and potential use of non-steroidal anti-inflammatory drugs (NSAID) as anti-cancer agents [3–5]. Although gastrointestinal bleeding and increased cardiovascular (CV) problems are associated with most of the known NSAIDs, naproxen is known for its fewer CV effects with a possible cardioprotective role in human . In a phase II clinical trial, naproxen was found to be safe and effective in treating progressive prostate cancer with early recurrent disease  and a recent study using a murine model of induced colon cancer, has also indicated the anti-cancer properties of this drug .
The molecular mechanisms, by which NSAIDs impart their chemopreventive effects, are a matter of intense debate till date. The most accepted hypothesis has focused on their property to reduce the levels of prostaglandins by cyclooxygenase (COX-1 and -2) inhibition . Over expression of COX-2  along with increased levels of prostaglandin E2 (PGE2) in breast cancer patients have been reported . It is of note that PGE2, a known COX-2-derived prostaglandin, plays a significant role in progression and metastasis of cancer cells by modulating local tumor microenvironment . Hence, molecules with an enhanced capacity to reduce PGE2 in cancer cells are of great interest.
Synthesis of naproxen derivatives (1–4)
All the naproxen derivatives were synthesized according to the methods described in our previously published literature .
The human breast cancer cell line MCF-7 and the mouse macrophage RAW 264.7 cells were cultured in high glucose Dulbecco's minimal essential medium (DMEM) supplemented with 10% FBS (Life Technologies) and 1% L-glutamine-penicillin-streptomycin (Life Technologies) and Insulin (in case of MCF-7), and maintained in a humidified incubator at 37°C and 5% CO2. MDA-MB-231, a rather aggressive form of human breast cancer cell line, was grown in Leibovitz's L-15 medium in presence of 10% fetal bovine serum and antibiotics, penicillin and streptomycin and required a 37°C incubator with 100% air environment for optimum growth. They grew as a monolayer in the culture plate and were regularly passaged at ~80% confluency.
Cell lines were purchased from ATCC (American Type Culture Collection, Manassas, VA, USA) and maintained in our cell culture facility.
Briefly, 104 cells/well were seeded in a 96-well plate and left to adhere overnight. Compounds were prepared as a stock (50 mM) in DMSO-media, prior to addition to the cells. The culture medium was replaced with medium containing the compounds at various concentrations (1 mM, 3 mM, 5 mM, 10 mM) and incubated for another 24 h following addition of 100 μl of 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT; 1 mg/ml) stain per well, incubated for 3 h at 37°C and subjected to DMSO (150 μl/well). Incubation was carried out further for another 10 min at 37°C, and the absorbance was recorded at 570 nm using a plate reader (VARIOSKAN, ThermoFisher).
Following treatment of cells (1.5 × 106 MDA-MB-231 cells/well in a 12-well plate) with naproxen sodium or 4 for two different time points, apoptosis was determined by “Apo-TRACE Apoptotic Cell Staining Kit” (# CS1110; Sigma), as per manufacturer’s instruction. Control cells were treated with DMSO-media. In principle, viable cells are Apo-TRACE-/PI-, dead or necrotic cells are Apo-TRACE-/PI+, early apoptotic cells are Apo-TRACE+/PI-, and late apoptotic cells are Apo-TRACE+/PI+.
To detect the levels of caspases-3, -8 and -9 in cell lysates from treated and untreated cells (1.5 × 106 MDA-MB-231 cells/well in a 6-well plate), Caspase Colorimetric Protease Assay Sampler Kit (# KHZ1001; Life Technologies) was used as per manufacturer’s protocol. In principle, active caspase 3, 8 or 9 cleaves the individual fluorogenic substrate to release the fluorochrome, which can be detected using a microtiter plate reader at 405 nm.
Cell cycle study
The amount of secreted PGE2, from treated and untreated cell (1.5 × 106 MDA-MB-231 cells/well in a 12-well plate) culture supernatants, was determined using Prostaglandin E2 EIA kit (Cayman Chemicals, Ann Arbor, MI). The conditioned medium was centrifuged to remove any cells and stored immediately at -70°C until assay. The assay was done according to the manufacturer’s protocol.
Cell migration assay
MDA-MB-231 cells were grown to confluency in a 9 cm2 culture plate. A 200 μl sterile pipette tip was used to introduce a scratch followed by treatment with different concentrations (1 mM and 3 mM) of naproxen sodium, 4 or DMSO. Still and/or video images were captured during or after 22 h to monitor wound closure rate to measure migration speed and polarity .
IC50 was calculated by nonlinear regression analysis using OriginPro. The mean and SD values were computed using Microsoft Excel, and GraphPad software was used to calculate p values.
Results and discussion
Enhanced cytotoxic killing is evident by naproxen-derivatives against MCF-7 and MDA-MB-231 cells
In vitro cytotoxicity of naproxen sodium and its derivatives
24-h IC50, mM
ER-, PR-, HER2/Neu-
Naproxen sodium (NS)
Treatment with 4 induces early apoptosis in MDA-MB-231 cells
Naproxen derivative 4 induces caspase-3/9 mediated apoptosis in MDA-MB-231 cells
Many researchers have commented on the crucial role of caspase-cascade system in apoptosis, and the role of caspase-8, -9 as executioner and -3 as death protease  is well accepted. Treatment with 4 (6 mM) for 6 h resulted in a significant increase in the activation of caspase -9 and -3 compared to its parent compound NS (Figure 2). These results suggest that the 4 mediated observed apoptosis in MDA-MB-231 cells is due to activation of caspases-3 and -9. Hence, our study clearly indicates involvement of the intrinsic pathway  of caspase activity in inducing apoptosis in MDA-MB-231 cells.
Neither NS nor 4 induces cell-cycle arrest in MDA-MB-231 cells
Naproxen derivative 4 inhibits PGE2synthesis in MDA-MB-231 cells
Treatment with 4 can slow-down cell-migration rate in MDA-MB-231cells
In vitro migration speed of control or treated MDA-MB-231 as determined by scratch wound assay
Drug Treatment (1 mM)
Migration speed (μm/h)
Here, we have presented a new peptide based derivative 4 obtained from the NSAID naproxen capable of showing cytotoxic property against two human breast cancer cell lines and, have also provided brief experimental evidence, supported by literature, to address the underlying mechanism of action. In summary our studies suggest that derivative 4 mediated cell-killing is due to an early induction of apoptotic event followed by activation of intrinsic caspase-cascade at a molecular level, while no sign of significant cell-cycle arrest was evident. Furthermore, we have showed that 4 can inhibit PGE2 synthesis and delay tumor cell migration (in vitro). Since the derivative 4 is capable of forming hydrogel at room temperature  it can also be employed as the hydrogel drug-delivery system  for sustained release of the anti-cancer agent. However, it is also important to note the difference in the IC50 vales of 4 against p53 wild type MCF-7 (~3 mM) and p53 null MDA-MB-231 (~6 mM) cells. The highly skewed killing of MCF-7 cells by this compound might indicate the involvement of p53 mediated apoptotic pathway. One of the major off target effects of 4 may include p53 targets such as bax. Further experimentation is needed to elucidate these potential off target effects of this novel anti-cancer compound. Potential limitation of this drug could be the fact that it may include p53 as one of its targets, thus the dose needed to induce significant killing may be relatively elevated for p53 muted cancer cells compared to p53 wild type cancer cells. Overall these studies imply that peptide based naproxen-derivative 4 can serve as an anti-cancer agent.
SSJ thanks DBT for financial support (CEIB project BT/01/CEIB/V/13). JD thanks DBT, New Delhi for RA Fellowship. JM thanks CSIR, New Delhi for SRF (CSIR Grant No. 09/080(0776)/2011-EMR-1). We are also grateful to Prof. Parthasarathi Dastidar and his group members, Department of Organic Chemistry, IACS, Kolkata; Mahua Rani Das, Sumit Kr. Dey and other group members of Dr. S.S. Jana, IACS, Kolkata, for technical support.
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