Understanding Drug Resistant Cervical Cancer Cells

Dr. Pontsho Moela, a researcher and lecturer at the University of Pretoria (South Africa), caught our attention with her Tweet showing her excitement at the installation of a new ZEISS Primovert microscope by her local ZEISS representative which will be used for cancer cell visualization.

We contacted her to find out more about her research and how she uses microscopy.

Tell us a little about yourself.

I am a lecturer of human genetics and I lead a research group that’s focusing on identification of therapeutic and diagnostic markers in breast and cervical cancer.

I realized my passion for research at honors level in school. I had wanted to become a medical doctor so that I can help my country in the fight against HIV/AIDS, which remains a burden to our society even today. However, fate landed me in a cancer research lab during my postgraduate studies, which I quickly developed a passion for as well, and this was mostly influenced by how prevalent both breast and cervical cancers are in South Africa.

What are your research goals?

I am currently interested in understanding the behavior of persister cells from cervical cancer cells in response to cisplatin and RBBP6 gene silencing.

Unstained cervical cancer cells. Image courtesy of Dr. Pontsho Moela, University of Pretoria (South Africa)

Unstained cervical cancer cells.

Cervical cancer cells showing RBBP6 expression (green) and nuclear marker DAPI. Image courtesy of Dr. Pontsho Moela, University of Pretoria (South Africa)

Cervical cancer cells showing RBBP6 expression (green) and nuclear marker DAPI.

Cisplatin is an FDA-approved chemotherapeutic drug that is generally used either as a single agent or in adjuvant therapy for cervical cancer. However, most cancer patients elicit resistance to this drug which is why there is still ongoing research on it to improve its efficacy.

The RBBP6 gene codes for the multifunctional regulatory protein called retinoblastoma-binding protein, which binds to the tumor suppressor proteins p53 and pRB. Research, including ours, has shown that RBBP6-knockdown cancer cells undergo a significant level of apoptosis and cell cycle arrest, compared to cells that overexpress RBBP6, which have been shown to accumulate in the S-phase. This, therefore, suggests the role of RBBP6 in cancer cell proliferation. Ongoing studies in our lab focus on elucidating the role of RBBP6 in cancer cell proliferation in cancer mice models.

Cervical cancer cells have a level of resistance towards cisplatin treatment and our research seeks to improve this by silencing the RBBP6 gene since it has been shown to promote cancer cell proliferation. We use RNAi technology to knockdown the RBBP6 gene in cancer cells and our previous studies show a strong apoptosis induction and cell cycle arrest in breast and cervical cancer cells post RBBP6 knockdown.

Tell us about some of your recent publications

Dr. Pontsho Moela, University of Pretoria (South Africa) with the ZEISS Primovert inverted tissue culture microscope

Dr. Pontsho Moela with the ZEISS Primovert inverted tissue culture microscope

In my last few publications (Moela et al. (2014) and Moela and Motadi (2016)), we had an interesting finding in that RBBP6 gene silencing resulted in a reduction in cancer cell growth in both breast and cervical cancer cells. This is an observation that validates our hypothesis. Since RBBP6 is found to be overexpressed in certain cancer cells, including these cancers, we hypothesized that the gene/protein is associated with cell proliferation and the promotion of cancer progression. This was further highlighted when silencing the gene resulted in a significant induction of apoptosis as well as the upregulation of the key apoptotic gene, bax, and the p53 transcription factor in MCF-7 cells. 

How do you use microscopy in your research?

We use microscopy to visualize our cell cultures and to image cells for morphology analysis using fluorescent dyes such as PI and DAPI staining. Viable, highly proliferative cells maintain their original shape, be it the spikey protrusions you see in epithelial HeLa cells or the dome structures you would normally see in MCF-7 monolayer cells. HEK293 is another cell line that shows a high level of RBBP6 expression as can be seen by immunostaining. However, when undergoing apoptotic cell death in response to RBBP6 silencing, these cells undergo morphological changes such as membrane blebbing, nuclei collapse, and an irregular overall shape, mainly as a result of permeabilization of the outer mitochondrial membrane for the release of cytochrome c and subsequent leakage of phosphatidylserine peptide through the porous lipid bilayer membrane as a result of apoptotic signals.

Unstained human embryonic kidney cells (HEK293) . Image courtesy of Dr. Pontsho Moela, University of Pretoria (South Africa)

Unstained human embryonic kidney cells (HEK293) imaged using brightfield microscopy.

Human embryonic kidney cells (HEK293) showing the abundance of RBBP6 in this transformed non-cancerous cell line. Image courtesy of Dr. Pontsho Moela, University of Pretoria (South Africa)

Human embryonic kidney cells (HEK293) showing the abundance of RBBP6 in this transformed non-cancerous cell line.

Learn More

Follow Dr. Moela’s Twitter feed to keep up to date on her research. Or learn more about the ZEISS Primovert inverted microscope for tissue culture and cancer research.

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