
<(From Left) Ph.D candidate Saemyeong Hong, Dr. Changgon Kim, Professor Joon Kim, Professor Ji Hun Kim>
In tissue biopsies, cancer cells are frequently observed to have nuclei (the cell's genetic information storage) larger than normal. Until now, this was considered a sign that the cancer was worsening, but the exact cause and effect had not been elucidated. In this study, the KAIST research team found that cancer cell nuclear hypertrophy is not a cause of malignancy but a temporary response to replication stress, and that it can, in fact, suppress metastasis. This discovery is expected to lead to the development of new diagnostic and therapeutic strategies for cancer and metastasis inhibition.
KAIST (President Kwang Hyung Lee) announced on the September 26th that a research team led by Professor Joon Kim of the Graduate School of Medical Science and Engineering, in collaboration with the research teams of Professor Ji Hun Kim and Professor You-Me Kim, discovered the molecular reason why the nucleus enlarges in cancer cells. This achievement provides an important clue for understanding nuclear hypertrophy, a phenomenon frequently observed in pathological examinations but whose direct cause and relationship with cancer development were unclear.
The research team confirmed that DNA replication stress (the burden and error signal that occurs when a cell copies its DNA), which is common in cancer cells, causes the 'actin' protein inside the nucleus to aggregate (polymerize), which is the direct cause of the nuclear enlargement.

<Mechanisms Inducing Nuclear Enlargement in Cancer Cells and Its Impact on Cellular Physiology>
This result suggests that the change in cancer cell nuclear size may not simply be a "trait evolved by the cancer cell for its benefit." Rather, it suggests that it is a temporary, makeshift response to stress, and that it may impose constraints on the cancer cell's potential for metastasis.
Therefore, future research needs to explore whether changes in nuclear size can become a target for cancer treatment or a clue related to the suppression of metastasis. That is, nuclear hypertrophy may be a temporary response to replication stress and should not necessarily be seen as indicating the malignancy of the cancer.
This conclusion was substantiated through: (1) Gene Function Screening (inhibiting thousands of genes sequentially to find the key genes involved in nuclear size regulation); (2) Transcriptome Analysis (confirming which gene programs are activated when the nucleus enlarges); (3) 3D Genome Structure Analysis (Hi-C), which revealed that nuclear hypertrophy is not just a size change but is connected to changes in DNA folding and gene arrangement; and (4) Mouse Xenograft Models (confirming that cancer cells with enlarged nuclei actually have reduced motility and metastatic ability).
Professor Joon Kim of the Graduate School of Medical Science and Engineering said, "We confirmed that DNA replication stress disrupts the nuclear size balance, explaining the underlying mechanism of long-standing pathological observations," adding, "The possibility of utilizing nuclear structural changes as a new indicator for cancer diagnosis and metastasis prediction has now opened up."
Dr. Changgon Kim (currently a Hematology and Oncology specialist at Korea University Anam Hospital) and Saemyeong Hong, a PhD candidate from the KAIST Graduate School of Medical Science and Engineering, participated as co-first authors in this study. The results were published online in the international journal PNAS (Proceedings of the National Academy of Sciences of the United States of America) on September 9th.
※ Paper Title: Replication stress-induced nuclear hypertrophy alters chromatin topology and impacts cancer cell fitness ※ DOI: https://doi.org/10.1073/pnas.2424709122
Meanwhile, this research was supported by the Mid-career Researcher Program and the Engineering Research Center (ERC) program of the National Research Foundation of Korea.
Immune cells can become exhausted after prolonged exposure to cancer, gradually losing their ability to attack tumor cells. This phenomenon is particularly pronounced in aggressive brain tumors and can severely limit the effectiveness of immunotherapy. A KAIST research team has now discovered that all-trans retinoic acid (ATRA), a vitamin A derivative, may help prevent such exhaustion and enhance the efficacy of immune checkpoint inhibitors. KAIST (President Choongsik Bae) announced on Septem
2026-09-08Once a cell has locked into an abnormal state — the way cancer cells do — can it ever be restored back to normal? A KAIST research team has identified the ‘molecular lock’ that keeps cells trapped in an altered state, opening a new path toward releasing that lock and reversing a cell’s fate. KAIST (President Choongsik Bae) announced on the 21st of August that a research team led by Professor Kwang-Hyun Cho of the Department of Bio and Brain Engineering has, for t
2026-08-21Even for the same brain tumor treated with the same anticancer drug, the effect can differ from patient to patient. A Korean research team has developed a chip that recreates a patient's own tumor cells together with the surrounding peritumoral vascular environment, making it possible to predict patient-specific treatment responses in advance. KAIST (President Choongsik Bae) announced on August 18 that a research team led by Professor Song Ih Ahn from the Department of Mechanical Engineering,
2026-08-18A new path has opened toward stopping cancer-associated cachexia, a devastating complication that gradually wastes patients away. A KAIST research team has developed an RNA-based therapeutic strategy that blocks a brain signal to prevent muscle loss and extend survival. KAIST (President Choongsik Bae) announced on the 2nd of August that a joint research team led by Professor Minho Shong and Professor Jinkuk Kim from the Graduate School of Medical Science and Engineering, together with the KAI
2026-08-03Cancer cells survive by hiding from the immune system's surveillance. A KAIST research team has developed a new anticancer platform that makes cancer cells send out their own danger signal—prompting immune cells to attack—while simultaneously delivering gene therapy. The approach is expected to offer a new treatment strategy that combines cancer immunotherapy and gene therapy in a single nanoparticle. Immunogenic cell death (ICD) is a process in which dying cancer cells send dange
2026-07-28