First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping researchers promote themselves alongside their papers. Neha Saxena is first author on ‘ Stiffness-dependent MSC homing and differentiation into CAFs – implications for breast cancer invasion’, published in JCS. Neha conducted the research described in this article while a PhD student in Professor Shamik Sen's lab at the Indian Institute of Technology Bombay, Mumbai, India. She is now a postdoctoral fellow in the lab of Professor Siddharth Dey, based in the Bioengineering Building, University of California, Santa Barbara, USA, investigating the role of the microenvironment in disease and the progression of embryonic development.

Neha Saxena

How would you explain the main findings of your paper in lay terms?

The tumor microenvironment is a complex community of different cell types, each playing a role in cancer progression. As time passes, cancer evolves, and one noticeable feature is increased stiffness of the extracellular matrix between cells. Imagine this stiffness as a barrier or roadblock within the body. This, coupled with the communication network between cells (crosstalk), has a significant impact on how cancer progresses. Additionally, cell–cell crosstalk further fuels cancer progression by allowing cancer cells to coordinate their actions. In simpler terms, the changes in stiffness and communication between cells collectively drive cancer to spread and become more aggressive. Understanding these aspects is crucial for developing strategies to disrupt this harmful partnership and better fight cancer.

In this work, we studied how extracellular matrix stiffness influences the crosstalk between cancer cells and mesenchymal stem cells (MSCs) using hydrogels of various stiffnesses corresponding to different stages of cancer progression. We show that on substrates mimicking the stiffness of pre-metastatic stroma, treatment of MSCs with medium conditioned with factors secreted by MDA-MB-231 breast cancer cells drives efficient MSC chemotaxis and induces stable differentiation of these MSCs into cancer-associated fibroblasts (CAFs) in a TGFβ- and contractility-dependent manner. Interestingly, in addition to enhancing cancer cell proliferation, CAFs grown on substrates mimicking pre-metastatic stroma maximally boost invasion and show increased resistance to flow-induced shear stresses.

Were there any specific challenges associated with this project? If so, how did you overcome them?

One of the most significant hurdles we faced involved working with microfluidic devices. Initially, conducting migration studies within a three-dimensional (3D) collagen matrix in the microfluidic device posed considerable challenges. Achieving a setup with cells embedded in 3D collagen on one side and only cell-free 3D collagen on the other side proved to be exceptionally challenging. Creating a stable chemokine gradient was the second major challenge. Another obstacle was designing a device capable of investigating the impact of shear stress on spheroids to mimic in vivo cancer clusters in blood vessels. It was challenging to get the spheroids to adhere inside the device prior to initiation of shear flow. However, persistent optimization of the methods ultimately led to the successful execution of migration experiments in the 3D microfluidic devices, addressing the challenges of both gradient stability and spheroid attachment.

When doing the research, did you have a particular result or ‘eureka’ moment that has stuck with you?

Absolutely! There was a striking ‘eureka’ moment during my research that has left a lasting impression. It happened when I observed the invasion experiment with spheroids composed of cancer cells and MSC-derived CAFs, each grown under different stiffness conditions. As I analyzed the results, a clear and visually impactful pattern emerged. In one specific condition, the CAFs were at the forefront of invasion, leading the way for the cancer cells that followed. This observation wasn't just a confirmation of our hypothesis; it also provided a vivid snapshot of the profound influence of substrate stiffness on the invasive behavior of the cells.

Why did you choose Journal of Cell Science for your paper?

Journal of Cell Science publishes high-quality peer-reviewed articles. With a diverse readership from the cell biology community, we see the potential for our work to reach a broad audience by publishing here. Additionally, we value the opportunity Journal of Cell Science offers to showcase the contributions of early-career researchers, providing a platform for both our work and professional development.

Spatial positioning of CAFs (red) and MDA-MB-231 cells (green) at the invasive front. Intensity profiles along lines drawn in the boxed regions show the relative positions of CAFs and MDA-MB-231 cells from front (F) to rear (R).

Spatial positioning of CAFs (red) and MDA-MB-231 cells (green) at the invasive front. Intensity profiles along lines drawn in the boxed regions show the relative positions of CAFs and MDA-MB-231 cells from front (F) to rear (R).

Have you had any significant mentors who have helped you beyond supervision in the lab? How was their guidance special?

I consider myself fortunate to have pursued my PhD under the guidance of Professor Shamik Sen. He is a distinguished mechanobiologist with a robust foundation in engineering and sound knowledge of biology. He has impressed me with his remarkable and interdisciplinary research approach. The intellectual freedom and constructive criticism provided by him not only facilitated my intellectual growth but also contributed to my growth as a researcher. His continuous inputs on every single experiment consistently guided my research in the right direction. I am immensely grateful for his comprehensive mentorship, and I couldn't have asked for a better advisor during my PhD.

What motivated you to pursue a career in science, and what have been the most interesting moments on the path that led you to where you are now?

From my earliest memories, my fascination with science has been a constant companion. From a young age, I found joy in understanding the intricacies of how things work, relishing the challenge of solving puzzles and constantly seeking to explore the unknown. However, the decision to embark on a research journey came much later for me during my master's thesis. It was during this pivotal period that the realization struck – research held the key to a truly fulfilling future for me. Fueled by this newfound determination, I actively pursued my passion for research, culminating in the gratifying achievement of securing a national-level fellowship for my PhD. Once I began my PhD, each successful experiment brought me immense joy, while the process of navigating challenges in less successful ones offered even greater satisfaction. Now, it has been more than nine years since I started my research journey, and I have enjoyed every single moment of it. Becoming a scientist has proven to be more than just a career choice for me; it feels like I have discovered the perfect vocation for my lifelong passion.

Who are your role models in science? Why?

Ever since I embarked on my journey of exploring the basics of science, all the major scientific discoveries and the brilliant minds behind them have inspired me. Among these, Gregor J. Mendel, the renowned geneticist, stands out as a significant role model for his groundbreaking work in genetics. His meticulous experiments with pea plants laid the foundation for our understanding of heredity and the principles of inheritance, sparking my lasting fascination with biology. Moreover, my admiration extends to other influential figures such as Charles Darwin, Watson and Crick, Marie Curie, and Albert Einstein, to name a few.

What's next for you?

Currently, I am working as a postdoctoral fellow in Professor Siddharth Dey's lab at the University of California, Santa Barbara. In the future, I would be interested in working in academia and encouraging more people to explore science.

Tell us something interesting about yourself that wouldn't be on your CV

I am deeply passionate about contributing to social causes. In collaboration with my parents and sister, I helped to establish a non-profit organization committed to offering educational opportunities for girls facing challenges in accessing schooling as a result of factors such as financial hardship or societal barriers.

Neha Saxena's contact details: Bioengineering Building, University of California, Santa Barbara, Santa Barbara, CA 93106-5080, USA.

E-mail: nehasaxena7@gmail.com

Saxena
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N.
,
Chakraborty
,
S.
,
Dutta
,
S.
,
Bhardwaj
,
G.
,
Karnik
,
N.
,
Shetty
,
O.
,
Jadhav
,
S.
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Zafar
,
H.
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Sen
,
S.
(
2024
).
Stiffness-dependent MSC homing and differentiation into CAFs – implications for breast cancer invasion
.
J. Cell Sci.
137
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jcs261145
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