Oncotarget. 2015 Aug 28;6(25):21255-67.

Spontaneously-forming spheroids as an in vitro cancer cell model for anticancer drug screening.

 

Theodoraki MA1, Rezende CO Jr2, Chantarasriwong O2,3, Corben AD4, Theodorakis EA2, Alpaugh ML2,5.
  • 1Department of Biology, Arcadia University, Philadelphia, PA, USA.
  • 2Department of Chemistry and Biochemistry, University of California – San Diego, La Jolla, CA, USA.
  • 3Department of Chemistry, Faculty of Science, King Mongkut’s University of Technology Thonburi, Bangkok, Thailand.
  • 4Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
  • 5Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, NY, USA.

 

Abstract

The limited translational value in clinic of analyses performed on 2-D cell cultures has prompted a shift toward the generation of 3-dimensional (3-D) multicellular systems. Here we present a spontaneously-forming in vitro cancer spheroid model, referred to as spheroidsMARY-X, that precisely reflects the pathophysiological features commonly found in tumor tissues and the lymphovascular embolus. In addition, we have developed a rapid, inexpensive means to evaluate response following drug treatment where spheroid dissolution indices from brightfield image analyses are used to construct dose-response curves resulting in relevant IC50 values. Using the spheroidsMARY-X model, we demonstrate the unique ability of a new class of molecules, containing the caged Garcinia xanthone (CGX) motif, to induce spheroidal dissolution and apoptosis at IC50 values of 0.42 +/-0.02 μM for gambogic acid and 0.66 +/-0.02 μM for MAD28. On the other hand, treatment of spheroidsMARY-X with various currently approved chemotherapeutics of solid and blood-borne cancer types failed to induce any response as indicated by high dissolution indices and subsequent poor IC50 values, such as 7.8 +/-3.1 μM for paclitaxel. Our studies highlight the significance of the spheroidsMARY-X model in drug screening and underscore the potential of the CGX motif as a promising anticancer pharmacophore.

KEYWORDS: breast cancer; drug screening; garcinia xanthone motif (CGX); lymphovascular embolus (LVE); natural products

PMID: 26101913

 

Synopsis

The biggest challenge of any preclinical model is the accurate replication of the pathophysiological and clinical characteristics of the targeted disease. Derived from a tumor explant of a woman diagnosed with inflammatory breast cancer (IBC), the MARY-X xenograft model grows exclusively within the murine lymphatic and blood vessels and leads to erythema of the overlying skin [1]. As such, it retains the tumor phenotype and mimics the aggressive metastatic characteristics of the disease. Interestingly, when cultured in vitro, the MARY-X model produces spheroids, referred to as spheroidsMARY-X, that assemble spontaneously into 3D structures and resemble the overall tumor profile, where the cells in the core of the spheroid are hypoxic and the cells at the periphery are highly proliferative [2]. The spheroidsMARY-X undergo cell death upon dissolution, so the loss of compaction (i.e. dissolution indices) of the spheroidsMARY-X can be used to monitor viability [2]. All the above characteristics make the spheroidsMARY-X an ideal system for use in drug development. In this manuscript, the authors have developed a fast, inexpensive and high-throughput method to evaluate drug potency using the spheroidsMARY-X. This assay consists of exposing the spheroidsMARY-X to different concentrations of one or more compounds for 24 hours in a multi-well plate, followed by acquisition of pictures from each well using a simple bright field microscope [2]. The developed strategy can be used to identify new small molecules that have high degree of clinical translation especially for metastatic and chemo-refractory cancers for which there are at-present not efficient therapies (Figure).

 

MA fig1

Figure: In vitro model with high degree of clinical translation.

References: 

  1. Alpaugh ML, Tomlinson JS, Shao ZM and Barsky SH. A novel human xenograft model of inflammatory breast cancer. Cancer Res. 1999; 59(20):5079-5084.
  2. Theodoraki MA, Rezende CO, Jr., Chantarasriwong O, Corben AD, Theodorakis EA and Alpaugh ML. Spontaneously-forming spheroids as an in vitro cancer cell model for anticancer drug screening. Oncotarget. 2015; 6(25):21255-21267.

 

 

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