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Researchers develop breast cancer spheroid models to study drug response and resistance

04 December 2024 | Story André Damons | Photo André Damons

Breast Cancer Research 2024 — The research team consist of Dr Beynon Abrahams (left), Viwe Fokazi, MMed.Sci student, and PhD student Songezo Vazi.

In an effort to better understand chemotherapeutic treatment response in triple negative breast cancer (TNBC) – known as an aggressive cancer with high recurrence and high mortality rate in breast cancer patients – researchers from the University of the Free State (UFS) developed a drug-resistant TNBC spheroid model that is physiologically more accurate in displaying the complexities involved in drug-resistance development.

Dr Beynon Abrahams, Lecturer in the Department of Basic Medical Sciences within the UFS Faculty of Health Sciences, says breast cancer remains the most frequently diagnosed cancer in women. It is also the most debilitating type of cancer responsible for the highest cancer mortality rates in women. Though various subtypes of breast cancer exist, TNBC is one that is of particular interest to his research team.

“TNBC is one of the most difficult cancer types to treat, due to lack of treatment targets. This often leads to treatment failure in TNBC patients, with drug resistance being a common occurrence, contributing to high death rates. TNBC is classified based on its lack of expression of common receptors such as the estrogen receptor, progesterone receptor and human epidermal growth factor receptor 2, which are commonly expressed in other cancer subtypes.

“Characteristically, TNBC is known as an aggressive cancer with high metastatic potential (spreading of cancer), resulting in a poor prognosis for these patients. The current prescribed therapies for TNBC, entails multidrug combination systemic therapy including chemotherapeutic agents such as doxorubicin and cisplatin as adjuvant therapy. However, despite these therapeutic interventions, drug resistance is a common occurrence,” says Dr Abrahams.

The best available preclinical cell-based models should be used

For effective drug treatments to be developed for TNBC therapeutics, he continues, the best available disease models should be used to not only improve our understanding of the disease physiology and its numerous mechanisms involved in chemotherapeutic resistance development but also to provide accurate results when determining how safe and effective newly developed drugs are, before they may be considered for further development and testing on humans.

According to him, in preclinical cancer research the conventional methods employed to study disease mechanisms, drug action and drug resistance is ineffective. Firstly, the traditionally used preclinical 2-dimensional (2-D) cell culture models do not accurately recapitulate the architectural biology observed in vivo, second, the drug responses assessed in these models may provide inaccurate results and limit its translational potential, explains Dr Abrahams. Thus, more advanced cell-based models such as 3-dimensional (3-D) spheroids and organoids to name a few, should be considered as alternatives.

The UFS research team, in collaboration with the Centre of Excellence for Pharmaceutical Sciences (Pharmacen™) at the North-West University (NWU), recently took the undertaking to establish two triple negative breast cancer 3-D spheroid models, using the clinostat rotating bioreactor ClinoStar™ system, designed by CelVivo in Denmark. The project is funded by the National Research Foundation.

The ClinoStar™ system promotes the self-aggregation of single cells, and natural formation of 3-D spheroids, through slow rotation within a cell growth chamber known as an incubator. There are various techniques and methods available to develop spheroids and organoids, however the ClinoStar™ systems allow for the development of metabolically stable spheroids, over a longer period of time, as opposed to other methods. It also eliminates the sheer-stress conditions that are normally encountered when using 2-D cell culture models.

“We successfully established one chemotherapeutic-sensitive triple negative breast cancer spheroid model and one novel cisplatin-resistant triple negative breast cancer spheroid model. The chemo-sensitive TNBC spheroid model was evaluated for responsiveness against two clinically used chemotherapeutic agents, doxorubicin and cisplatin. We suggest that this model may be useful to screen novel compounds including traditionally used phytomedicinal material for anticancer activity.

“In our second model, the cisplatin-resistant TNBC spheroid model was also exposed to cisplatin and doxorubicin and demonstrated a resistant response in terms of growth and viability. We believe that this model may be useful to further explore drug resistance mechanisms and may also be used as a tool to assess the drug reversal potential of novel compounds. The value and impact of these models lies in that they may offer predictive drug responses that are closer to that observed in in vivo (animals), as opposed to 2-D cell cultures. This however needs to be assessed. We are currently in the process to fully characterise these spheroids models.”

Aim of the research

Dr Abrahams explains their research aims to merge the gap between conventionally used 2-D cell models and in vivo models, by providing a model that is physiologically more accurate in mimicking the in vivo conditions and complex pathways associated with drug resistance, which is otherwise not observed or accurately expressed in 2D models. “Although our research is preclinical and considered fundamental basic research, the translational potential of our spheroid models may provide options for exploring and testing alternative drugs that may be considered for translational research,” Dr Abrahams says.

Characterising other advanced cell-based cancer models

The team is currently in the process of further characterising the TNBC spheroid model based on protein and genetic expression profiles to elucidate potential therapeutic biomarkers for drug treatment as well as screening various phytomedicinal plants, to assess their antiproliferative and drug-resistance reversal potential. In addition, the researchers recently commenced a new research project that aims to develop a drug-resistant prostate cancer spheroid model using the Clinostar™ system with their collaborators at the NWU.

Advanced cell-based model research is still relatively ‘new’ in South Africa and Africa, compared to the global North. As a result, says Dr Abrahams, their NWU collaborators together with other stakeholders, initiated the establishment of the Society for Advanced Cell Culture Modelling for Africa (SACCMA) in 2021, which aims to develop the fields of advanced cell modelling, three-dimensional (3D) cell cultures, 3D bioprinting and stem cell research, in Africa. Our current inter-departmental collaboration include researchers from the Pharmacology department, but we hope to build and expand our collaboration network in the near future.

News Archive

Research by experts published in Nature

2011-06-02

The members of the research group are, from the left, front: Christelle van Rooyen, Mariana Erasmus, Prof. Esta van Heerden; back: Armand Bester and Prof. Derek Litthauer.
Photo: Gerhard Louw

A research article on the work by a team of experts at our university, under the leadership of Prof. Esta van Heerden, and counterparts in Belgium and the USA has been published in the distinguished academic journal Nature today (Thursday, 2 June 2011).

The article – Nematoda from the terrestrial deep subsurface of South Africa – sheds more light on life in the form of a small worm living under extreme conditions in deep hot mines. It was discovered 1,3 km under the surface of the earth in the Beatrix Goldmine close to Welkom and is the first multi-cellular organism that was found so far beneath the surface of the earth. The worm (nematode) was found in between a rock face that is between 3 000 and 12 000 years old.

The research can shed some new light on the possibility of life on other planets, previously considered impossible under extreme conditions. It also expands the possibilities into new areas where new organisms may be found.

These small invertebrates live in terrestrial soil subjected to stress almost for 24 hours They live through sunshine, rain, scorching temperatures and freezing conditions. Through time they developed a means to cope with harsh conditions. Terrestrial nematodes (roundworms, not to be confused or related to earthworms) are among those very tough small invertebrates that deal with those conditions everywhere. After insects they are the most dominant multi-cellular (metazoan) species on the planet having a general size of 0,5 to 1 mm and are among the oldest metazoans on the planet, Nature says in a statement on the article.

They inhabit nearly every imaginable habitat form the deep seas to the acid in pitcher . Some nematodes simply eat bacteria and these are the ones we study here. Terrestrial nematodes have developed a survival stage that can take them through hard times (absence of food, extreme temperatures, too little oxygen, crowding, and more).

At the head of the research was Prof. Gaetan Borgonie of the Ghent University in Belgium and a world leader in the discipline of nematode research. He was brought into contact with the South African research leader, Prof. Esta van Heerden, who set up a cooperation agreement with the University of Ghent and Prof. Borgonie. Prof. Van Heerden manages the Extreme Biochemistry group at the UFS and the research was funded by several research grants.

The search for worms began in earnest in 2007, but it was soon clear that the sampling strategy was insufficient. A massive sampling campaign in 2008-2009 in several mines led to the discovery of several nematodes and the new nematode species Halicephalobus mephisto. It is named after the legend of Faust where the devil, also known as the lord of the underworld is called Mephistopheles.

Nature says special filters had to be designed and installed on various boreholes. Unfortunately, there is no easy way of finding a magic formula and designs had to be adapted by trial and error; improving existing designs all the time. The work of the UFS Mechanical Workshop, which manufactured, adapted and helped design it, was crucial in this respect. Filters were left on the holes for varying periods, sometimes for a few hours and sometimes for months. Prof. Derek Litthauer from the UFS played a big role in sampling, filter designs and coming up with ideas for names for the new nematode with Prof. Borgonie.

Research showed that the nematodes can live in the deep for up to 12 000 years. Three students – Armand Bester, Mariana Erasmus and Christelle van Rooyen from the UFS – did the work on this.

The importance of multi-cellular animals living in the ultra-deep subsurface is twofold: The nematodes graze on the existing bacterial population and influence their turnover. Secondly, if more complex multi-cellular organisms can survive in the deep subsurface on earth, this may be good news when looking for life on other planets where the surface is considered too inhospitable (e.g. Mars). Complex life forms can be found in ecosystems previously thought to be uninhabitable. Nature says this expands the possibilities into new areas where new organisms may be discovered.

Future research will focus on selective boreholes to look for more metazoans, so that a better idea of the complexity of the ecosystems there can be obtained. It will also look for metazoans in the deep subsurface on other continents to determine similarities and differences.

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