Original Article
Liposome-mediated delivery of the p21 activated kinase-1 (PAK-1) inhibitor IPA-3 limits prostate tumor growth in vivo

https://doi.org/10.1016/j.nano.2016.01.003Get rights and content

Abstract

P21 activated kinases-1 (PAK-1) is implicated in various diseases. It is inhibited by the small molecule ‘inhibitor targeting PAK1 activation-3’ (IPA-3), which is highly specific but metabolically unstable. To address this limitation we encapsulated IPA-3 in sterically stabilized liposomes (SSL). SSL-IPA-3 averaged 139 nm in diameter, polydispersity index (PDI) of 0.05, and a zeta potential of − 28.1, neither of which changed over 14 days; however, the PDI increased to 0.139. Analysis of liposomal IPA-3 levels demonstrated good stability, with 70% of IPA-3 remaining after 7 days. SSL-IPA-3 inhibited prostate cancer cell growth in vitro with comparable efficacy to free IPA-3. Excitingly, only a 2 day/week dose of SSL-IPA-3 was needed to inhibit the growth of prostate xenografts in vivo, while a similar dose of free IPA-3 was ineffective. These data demonstrate the development and clinical utility of a novel liposomal formulation for the treatment of prostate cancer.

Graphical abstract

The small molecule ‘inhibitor targeting P21-activated kinase-1 (PAK1) activation-3’ (IPA-3) has potential anti-cancer effects, but is metabolically unstable. We encapsulated IPA-3 in sterically stabilized liposomes (SSL) that averaged 139 nm in diameter, polydispersity index (PDI) of 0.05, and a zeta potential of − 28.1, which was stable for over 14 days with 70 % of IPA-3 remaining even after 7 days. A 2 day/week administration of 5 mg/kg dose of SSL-IPA-3 significantly inhibited the growth of prostate xenografts in vivo as compared to similar dose of free IPA-3, demonstrating the potential benefits of SSL-IPA-3 for the management of prostate cancer.

  1. Download : Download high-res image (208KB)
  2. Download : Download full-size image

Section snippets

Cell lines and cell culture

The human prostate cancer cell lines PC-3, LNCaP and DU-145 and the breast cancer cell lines MCF-7 and MDA-231 were purchased from ATCC (Manassas, VA). PC-3, LNCaP, and DU-145 cells were cultured in F12K, RPMI, and EMEM, respectively. MCF-7 and MDA-231 cells were cultured in RPMI. All culture media were supplemented with 10% FBS and 1% penicillin/streptomycin antibiotics (ATCC). All cells were maintained at 37 °C in incubators with 5% CO2 and humidified atmosphere.

Chemicals and reagents

IPA-3 was purchased from Tocris

Characterization of SSL-IPA-3

SSL-IPA-3 (Table 1) had a hydrodynamic particle diameter of approximately 139 nm, and this value did not change significantly over a period of two weeks (Table 2). The polydispersity index (PDI), a measure of the distribution of diameters was maintained at values less than 0.14 for up to 14 days. These PDI values are within the recommended size for medical applications, which is a PDI of less than 0.3.26 The zeta potential (the overall surface charge of the particles) also did not significantly

Discussion

Serine–threonine kinases PAKs, PAK-1 in particular, have been associated with a variety of pathological conditions, including cancer.1 PAK-1 is regulated by auto-inhibition, and is suggested as a good therapeutic target for cancer therapy by using small molecules that may cause conformational changes in the protein disturbing its autoregulation.1, 27 Previous studies from our laboratory showed that Rac1, an upstream regulator of PAK-1 promotes prostate cancer cell survival, proliferation and

Acknowledgments

The authors would like to thank Mr. Nhat D. Quach for his technical support during liposome preparation.

References (32)

  • G. Zhu et al.

    Secretory phospholipase A(2) responsive liposomes

    J Pharm Sci

    (2011)
  • G.M. Cheetham

    Novel protein kinases and molecular mechanisms of autoinhibition

    Curr Opin Struct Biol

    (2004)
  • C. Chen et al.

    An overview of liposome lyophilization and its future potential

    J Control Release

    (2010)
  • J.V. Kichina et al.

    PAK1 as a therapeutic target

    Expert Opin Ther Targets

    (2010)
  • M. Radu et al.

    PAK signalling during the development and progression of cancer

    Nat Rev Cancer

    (2014)
  • A. Goc et al.

    Rac1 activation driven by 14-3-3 zeta dimerization promotes prostate cancer cell–matrix interactions, motility and transendothelial migration

    PLoS One

    (2012)
  • Cited by (28)

    • PAK1 inhibitor IPA-3 mitigates metastatic prostate cancer-induced bone remodeling

      2020, Biochemical Pharmacology
      Citation Excerpt :

      Primary antibodies against PAK1 (1:1000) (Cat # 2602S) and GAPDH (1:5000) (Cat # 5174S) were purchased from Cell Signaling (Danvers, MA). Cell proliferation and viability were determined as previously published from our laboratory using the MTT assay (Thermo Fisher, Waltham, MA) [17,18]. Cells were seeded in 48-well cell culture plates at 5 × 104 cells/ml and incubated at 37 °C in a 5% CO2 incubator for 24 h. Cells were treated with 10, 20 and 30 µM IPA-3 inhibitor (Tocris BioScience; Minneapolis, MN, Cat# 3622) and DMSO (vehicle) and were incubated for 24 h. MTT was added at this time point, at a final concentration of 0.25 mg/ml and plates were incubated at 37 °C.

    • Liposomes and drug-in-cyclodextrin-in-liposomes formulations encapsulating 17β-estradiol: An innovative drug delivery system that prevents the activation of the membrane-initiated steroid signaling (MISS) of estrogen receptor α

      2020, International Journal of Pharmaceutics
      Citation Excerpt :

      Moreover, these nanovectors can reduce the drug toxicity as well as decrease the administered dose (Al-Jamal and Kostarelos, 2011), influence the drug cellular delivery (Murata, 2012) and the in vivo distribution (Wang and Huang, 2011). Liposomes formulations are widely studied for the treatment of many pathologies, such as cancer (Al-Azayzih, 2016; Soni et al., 2008), multiple sclerosis (Schmidt, 2003), Parkinson’s (Zhang et al., 2003) and Alzheimer’s (Nardo et al., 2016) diseases or infections (Cipolla et al., 2016). Furthermore, liposomes are often used in many applications, like protein delivery (Kowapradit et al., 2012), vaccine formulation (Michalek et al., 1989), diagnostic (Magin et al., 1986) or gene therapy (Lechanteur et al., 2015).

    • Development of injectable liposomes and drug-in-cyclodextrin-in-liposome formulations encapsulating estetrol to prevent cerebral ischemia of premature babies

      2019, European Journal of Pharmaceutical Sciences
      Citation Excerpt :

      Moreover, these nanovectors can reduce the drug toxicity as well as decrease the administered dose (Al-Jamal & Kostarelos, 2011), influence the drug cellular delivery (Murata et al., 2012) and the in vivo distribution (Wang & Huang, 2011). Liposome formulations are widely studied for the treatment of many pathologies, such as cancer (Al-Azayzih et al., 2016; Soni et al., 2008), multiple sclerosis (Schmidt et al., 2003), Parkinson's (Zhang et al., 2003) and Alzheimer's (Nardo et al., 2016) diseases or infections (Cipolla et al., 2016). Furthermore, liposomes are often used in many applications, like protein delivery (Kowapradit et al., 2012), vaccine formulation (Michalek et al., 1989), diagnostic (Magin et al., 1986) or gene therapy (Lechanteur et al., 2015).

    View all citing articles on Scopus

    Conflicts of interest: The authors have declared that no conflicts of interest exist.

    Financial support: Funds were provided by the National Institutes of Health (Grant R01HL103952), the UGA-College of Pharmacy, UGA Research Foundation and the American Legion to PRS, National Institutes of Health (Grant R01EB0116100) to B.S.C., and an Achievement Reward for College Scientists Foundation Award to W.N.M. Research was supported with resources and the use of facilities at the Charlie Norwood VAMC, Augusta, GA. The funders had no role in the study design, data collection, analysis and decision to publish. Preparation of the manuscript and the contents do not represent the views of the Department of Veterans Affairs or the United States Government.

    1

    These authors contributed equally to this work.

    View full text