This article was originally published by UCLA Chemistry & Biochemistry
Statistical Parametrization of Cell Cytoskeleton (SPOCC) is an image processing method developed by
Professor Shimon Weiss’ group at UCLA.
Weiss (
pictured left) holds UCLA’s Dean M. Willard Chair in Chemistry and is a physical chemistry professor and a professor of physiology in the David Geffen School of Medicine. He is also a professor in the physics department at Bar Ilan University, Israel. Dr. Arkaprabha Basu (pictured right) received his Ph.D. in chemistry from UCLA in 2021 and is currently a postdoctoral fellow at Harvard University working on the involvement of liquid-liquid phase separation in cell cytoskeleton in Professor David Weitz’s group.
A healthy human cell may transform into a cancer cell upon mutation. The process of which the cancer cells become invasive is known as Epithelial Mesenchymal Transition (EMT). In the case of lung cancer, mutated cells will go through multiple intermediate states before reaching its final form that is highly invasive, motile and capable of metastasizing.
SPOCC is able to capture the intermediate EMT states in real time using actin cytoskeleton as the biomarker and successfully track EMT in live and fixed cells. Their work was recently published in
Communications Biology.
“Every cell has an actin cytoskeleton which reorganizes throughout EMT and that makes it a more ubiquitous feature to study,” Basu said. “Though the overall actin rearrangement is reported, studying and quantifying its gradual evolution in single cells as well as populations is the major novelty of our work.”
The team used the angular distribution of the actin cytoskeleton to calculate the Orientational Order Parameter, which serves as an effective figure of merit for stress fiber alignment that can monitor the EMT progression.
Current approaches to track EMT include simple biochemical experiments and mass cytometry studies to analyze EMT marker proteins. However, these techniques can be expensive and more importantly, destructive to the sample cell, which prevents progressive assessment on the cell. On the other hand, SPOCC is non-destructive in quantifying the changes in the properties of actin cytoskeleton, including its length, numbers, location and rearrangement with significant confidence. This provides further insight into the mobility, stiffness and other biophysical factors of the cells. Hence, SPOCC is advantageous for understanding mechanism and drug development, which can potentially intervene cancer cells at the intermediate states to stop its further invasiveness.
“This work was done on two dimensional cultured cells,” Basu said. “We intend to extend the application of SPOCC in tissue sections and organoids in the near future.”
The project is a collaborative effort with Professor Steven M. Dubinett and Dr. Manash Paul (UCLA Department of Pulmonary Disease), Professor Anna Grosberg (University of California, Irvine), and Professor Hichem Sahli and Dr. Mitchel Alioscha-Perez (Vrije Universiteit Brussel, Belgium).
While certain parts of the code for SPOCC was developed in Belgium and Irvine, Basu put it all together into a single technique ready for application.
“The main challenge in carrying out this research was funding,” Basu said. “We hope UCLA will introduce smaller short-term grants for promising projects that need immediate funding but are not ready for NIH or NSF level proposals.”
The next step is to integrate SPOCC into ImageJ, a free image visualization and analysis software that is widely used by scientists throughout the world. A plugin in ImageJ would broaden SPOCC users and make it more accessible to the public.
By Zhuoying Lin, UCLA Department of Chemistry & Biochemistry, zylin@g.ucla.edu. Lin is a first year chemistry graduate student and science writer.
