Nav: Home

Dying cancer cells make remaining glioblastoma cells more aggressive and therapy-resistant

June 21, 2018

BIRMINGHAM, Ala. - A surprising form of cell-to-cell communication in glioblastoma promotes global changes in recipient cells, including aggressiveness, motility, and resistance to radiation or chemotherapy.

Paradoxically, the sending cells in this signaling are glioblastoma cells that are undergoing programmed cell death, or apoptosis, according to research by a team at institutes in the United States, Russia and South Korea.

The dying cancer cells send their signals by means of extracellular vesicles induced and released during apoptosis. These vesicles -- small, membrane-bound blobs known as exosomes -- carry components that alter RNA splicing in the recipient glioblastoma cells, and this altered splicing promotes therapy resistance and aggressive migration.

This mechanism thus becomes a possible target for new therapies to treat glioblastoma, a primary brain cancer, and the mechanism may apply to other cancer types as well.

"Clinically, our data may provide the rationale to the molecular targeting of RNA splicing events or specific splicing factors for novel cancer therapies," said Ichiro Nakano, M.D., Ph.D., leader of the international study being published in Cancer Cell. "This may lead to decreased acquisition of therapy resistance, as well as reduction in the migration of cancer cells."

Nakano is an academic neurosurgeon at the University of Alabama at Birmingham who conducts both brain tumor translational research and clinical brain tumor surgery. He is professor of neurosurgery in the UAB School of Medicine and a senior scientist for the UAB Comprehensive Cancer Center.

Glioblastoma exhibits invasive behavior, abrupt growth and poor patient survival. As the number of the cancer cells rapidly increases, abundant apoptotic tumor cells are intermingled with neighboring proliferating tumor cells. The apoptotic cells can account for up to 70 percent of the tumor cell population.

The discovery of this unusual cell-to-cell communication began with a simple experiment -- injecting a combination of lethally irradiated human glioblastoma cells, which makes them apoptotic, and "healthy" glioblastoma cells into a mouse xenograft model. This combination led to much more aggressive tumor growth, as seen in brain scans, compared to "healthy" glioblastoma cells or irradiated glioblastoma cells alone. The combination was also more therapy-resistant.

The UAB researchers and colleagues found that, after induction of apoptosis, glioblastoma cells shed significantly higher numbers of exosomes with larger average sizes.

Those apoptotic exosomes, when combined with "healthy" glioblastoma cells, significantly increased tumor growth in the xenograft model and cell motility in bench experiments. Also, while the "healthy" glioblastoma cells alone had a clear border between the tumor and adjacent normal tissue in the xenograft, the glioblastoma cells co-injected with apoptotic exosomes invaded into adjacent brain tissue. Exosomes shed by non-apoptotic cells did not have these effects.

To discover the mechanism underlying these changes, the researchers looked at what was inside the apoptotic exosomes. The vesicles were enriched with spliceosomal proteins and several U snRNAs -- parts of the cellular machinery that remove introns from pre-messenger RNA.

These are normally confined to the nuclei of cells; but the Nakano team found that, as the glioblastoma cells underwent apoptosis, the spliceosomal proteins were transported out of the nucleus to the cell cytoplasm, where they could be packaged into vesicles for release.

Glioblastoma cell subtypes include the proneural subtypes and the mesenchymal subtype. Recent data have shown that, after therapy, glioblastoma cells shift from the less aggressive proneural subtype to the more aggressive and therapy-resistant mesenchymal subtype. The researchers found that apoptotic exosomes induced substantial alternate RNA splicing in recipient cells that resembled the splicing patterns found in the mesenchymal glioblastoma subtype.

Part of this was caused by the splicing factor RBM11, which is encapsulated in the vesicles. The researchers found that exogenous RBM11 caused upregulation of endogenous RBM11 in the recipient cells and activated glycolysis. Overexpression of RBM11 increased the migration of glioblastoma cells.

They also found that RBM11 altered RNA splicing to produce an isoform of the protein cyclinD1 that promotes DNA repair and an isoform of the protein MDM4 that has significantly higher anti-apoptotic activity. These changes can make the cells more therapy-resistant.

Examination of the Cancer Genome Atlas database showed that elevated expression of those two isoforms is associated with poor prognoses for glioblastoma patients.

Finally, the Nakano-led team looked at paired glioblastoma specimens of primary and recurrent tumors from matched patients. In most of the 43 pairs of matched samples, the RBM11 protein levels were substantially higher in the recurrent glioblastoma compared to the original, untreated tumors. In two other patient cohorts, they found that the higher RBM11 levels correlated with poor post-surgical survival for glioma patients.
-end-
Beside Nakano, co-authors of the paper, "Apoptotic cell-derived extracellular vesicles promote malignancy of glioblastoma via intercellular transfer of splicing factors," are Marat S. Pavlyukov, Hai Yu, Soniya Bastola, Mutsuko Minata, Suojun Zhang, Jia Wang, Svetlana Komarova, Jun Wang, Shinobu Yamaguchi and Heba Allah Alsheikh, UAB Department of Neurosurgery; Victoria O. Shender, Ksenia Anufrieva, Nadezhda V. Antipova, Georgij P. Arapidi, Vadim Govorun, Nikolay B. Pestov and Mikhail I. Shakhparonov, the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow, Russia; Yeri Lee, Yong Jae Shin and Do-Hyun Nam, Sungkyunkwan University School of Medicine, Seoul, Korea; Ahmed Mohyeldin, Junfeng Shi and L. James Lee, Ohio State University, Columbus, Ohio; Dongquan Chen, UAB Division of Preventive Medicine; Sung-Hak Kim, Chonnam National University, Gwangju, Korea; and Evgeniy G. Evtushenko, Lomonosov Moscow State University, Moscow, Russia.

This work was supported by NIH grants NS083767, NS087913, CA183991 and CA201402; Russian Foundation for Basic Research grants 16-04-01414, 16-04-01209 and 17-29-06056; and Russian Science Foundation grants 17-75-20205 and 16-14-10335; and by the Scholarships of the President of the Russian Federation SP-4811.2018.4.

At UAB, Nakano surgically cares for brain tumor patients. For any questions about his clinical program, call 205-996-2098 during working hours or 205-572-9703 at night or on weekends.

University of Alabama at Birmingham

Related Cancer Cells Articles:

Scientists have identified the presence of cancer-suppressing cells in pancreatic cancer
Researchers have identified cells containing a protein called Meflin that has a role in restraining the progression of pancreatic cancer.
Changes in the metabolism of normal cells promotes the metastasis of ovarian cancer cells
A systematic examination of the tumor and the tissue surrounding it -- particularly normal cells in that tissue, called fibroblasts -- has revealed a new treatment target that could potentially prevent the rapid dissemination and poor prognosis associated with high-grade serous carcinoma (HGSC), a tumor type that primarily originates in the fallopian tubes or ovaries and spreads throughout the abdominal cavity.
The development of brain stem cells into new nerve cells and why this can lead to cancer
Stem cells are true Jacks-of-all-trades of our bodies, as they can turn into the many different cell types of all organs.
White blood cells related to allergies may also be harnessed to destroy cancer cells
A new Tel Aviv University study finds that white blood cells which are responsible for chronic asthma and modern allergies may be used to eliminate malignant colon cancer cells.
Conversion of breast cancer cells into fat cells impedes the formation of metastases
An innovative combination therapy can force malignant breast cancer cells to turn into fat cells.
Breast cancer cells in mice tricked into turning into fat cells
As cancer cells respond to cues in their microenvironment, they can enter a highly plastic state in which they are susceptible to transdifferentiation into a different type of cell.
Brain cancer: Typical mutation in cancer cells stifles immune response
The exchange of a single amino acid building block in a metabolic enzyme can lead to cancer.
Researchers find prostate cancer drug byproduct can fuel cancer cells
A genetic anomaly in certain men with prostate cancer may impact their response to common drugs used to treat the disease, according to new research at Cleveland Clinic.
Dying cancer cells make remaining glioblastoma cells more aggressive and therapy-resistant
A surprising form of cell-to-cell communication in glioblastoma promotes global changes in recipient cells, including aggressiveness, motility, and resistance to radiation or chemotherapy.
An index measures similarity between cancer cells and pluripotent stem cells
The new methodology measures tumor aggressiveness and the risk of relapse, helping doctors plan treatment, according to Brazilian scientists authors of a paper published in a special issue of the journal Cell.
More Cancer Cells News and Cancer Cells Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#538 Nobels and Astrophysics
This week we start with this year's physics Nobel Prize awarded to Jim Peebles, Michel Mayor, and Didier Queloz and finish with a discussion of the Nobel Prizes as a way to award and highlight important science. Are they still relevant? When science breakthroughs are built on the backs of hundreds -- and sometimes thousands -- of people's hard work, how do you pick just three to highlight? Join host Rachelle Saunders and astrophysicist, author, and science communicator Ethan Siegel for their chat about astrophysics and Nobel Prizes.