Cookie Settings

We use cookies to optimize our website. These include cookies that are necessary for the operation of the site, as well as those that are only used for anonymous statistic. You can decide for yourself which categories you want to allow. Further information can be found in our data privacy protection .


These cookies are necessary to run the core functionalities of this website and cannot be disabled.

Name Webedition CMS
Purpose This cookie is required by the CMS (Content Management System) Webedition for the system to function correctly. Typically, this cookie is deleted when the browser is closed.
Name econda
Purpose Session cookie emos_jcsid for the web analysis software econda. This runs in the “anonymized measurement” mode. There is no personal reference. As soon as the user leaves the site, tracking is ended and all data in the browser are automatically deleted.

These cookies help us understand how visitors interact with our website by collecting and analyzing information anonymously. Depending on the tool, one or more cookies are set by the provider.

Name econda
Purpose Statistics
External media

Content from external media platforms is blocked by default. If cookies from external media are accepted, access to this content no longer requires manual consent.

Name YouTube
Purpose Show YouTube content
Name Twitter
Purpose activate Twitter Feeds

Breast cancer: Microproteins essential for cancer growth

No. 33c | 30/05/2018 | by Eck

Breast cancer is one of the leading causes of death in women worldwide. In order to develop new therapies, it is necessary to understand exactly how breast cancer cells function. Scientists at the German Cancer Research Center have taken an important step in this direction: In tumor tissue from breast cancer patients, they discovered a tiny protein that is essential for the growth of the tumor cells. If the gene for the microprotein is switched off, the growth of the breast cancer cells is inhibited.

The breast cancer cell line MCF7 produces the microprotein CASIMO1 (green). Shown in red is the cytoskeleton protein actin, the cell nuclei appear blue.
© M. Polycarpou-Schwarz; S. Diederichs, DKFZ

In women, breast cancer is the most common cancer. One in eight women suffers from a malignant tumor in her breast during her life. The type of breast cancer is crucial for prognosis and therapy. Depending on certain receptors on the surface of the cancer cells, the tumors are divided into two groups: hormone receptor positive and hormone receptor negative breast cancer. Most tumors of the breast are hormone receptor-positive, the cancer cells carry on their surface receptors for the sex hormones estrogen and progesterone.

"Although the group of hormone receptor-positive tumors has a better prognosis than other breast cancers, they are responsible for many deaths simply because of their frequency," explains Sven Diederichs of the German Cancer Research Center. "To find new ways to treat breast cancer, we first need to understand exactly how the tumor cells work. So far, our knowledge about the development and progression of the disease is not enough to treat it optimally, "he emphasizes.

Diederichs and his team compared breast cancer cells with breast tissue cells of healthy women. They found that a particular microprotein was much more common in breast cancer cells than in normal cells.

Microproteins have not been known for a long time. To produce a microprotein, the cell reads genetic material that has long been thought to contain no protein instructions. "Molecular biology databases are teeming with these supposedly noncoding RNA molecules, which are sometimes used by the cells to produce small proteins," Diederichs says.

In recent years, microproteins have been found to play a role in muscle development and cardiovascular disease. The microprotein CASIMO1, which was discovered by the DKFZ researchers and consists of just 83 amino acids, is the first to show any function in cancer.

CASIMO1 is present in breast cancer cells, especially of hormone receptor-positive tumors, in high concentration. The underlying gene is used extensively for protein production. In experiments on cell cultures, the scientists around Diederichs switched off the CASIMO1 gene. This demonstrated the importance of CASIMO1 for the survival of breast cancer cells: The lack of the microprotein interrupted the cell cycle of the breast cancer cells and thus inhibited their growth.

Next, the DKFZ scientists want to examine other microproteins that they have already found in patients with breast cancer or lung cancer. "The long-term hope is to be able to use these small proteins as therapeutic targets and to inhibit them with drugs," says Diederichs.

Maria Polycarpou-Schwarz, Matthias Groß, Pieter Mestdagh, Johanna Schott, Stefanie E. Grund, Catherina Hildenbrand, Joachim Rom, Sebastian Aulmann, Hans-Peter Sinn, Jo Vandesompele, Sven Diederichs. The cancer-associated microprotein CASIMO1 controls cell proliferation and interacts with squalene epoxidase modulating lipid droplet formation. Oncogene (2018), DOI: 10.1038/s41388-018-0281-5

A picture is available for download:

Picture Caption: The breast cancer cell line MCF7 produces the microprotein CASIMO1 (green). Shown in red is the cytoskeleton protein actin, the cell nuclei appear blue.

Note on use of images related to press releases
Use is free of charge. The German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ) permits one-time use in the context of reporting about the topic covered in the press release. Images have to be cited as follows: “Source: M. Polycarpou-Schwarz; S. Diederichs, DKFZ”.

Distribution of images to third parties is not permitted unless prior consent has been obtained from DKFZ’s Press Office (phone: ++49-(0)6221 42 2854, E-mail: Any commercial use is prohibited.

With more than 3,000 employees, the German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ) is Germany’s largest biomedical research institute. DKFZ scientists identify cancer risk factors, investigate how cancer progresses and develop new cancer prevention strategies. They are also developing new methods to diagnose tumors more precisely and treat cancer patients more successfully. The DKFZ's Cancer Information Service (KID) provides patients, interested citizens and experts with individual answers to questions relating to cancer.

To transfer promising approaches from cancer research to the clinic and thus improve the prognosis of cancer patients, the DKFZ cooperates with excellent research institutions and university hospitals throughout Germany:

  • National Center for Tumor Diseases (NCT, 6 sites)
  • German Cancer Consortium (DKTK, 8 sites)
  • Hopp Children's Cancer Center (KiTZ) Heidelberg
  • Helmholtz Institute for Translational Oncology (HI-TRON Mainz) - A Helmholtz Institute of the DKFZ
  • DKFZ-Hector Cancer Institute at the University Medical Center Mannheim
  • National Cancer Prevention Center (jointly with German Cancer Aid)
The DKFZ is 90 percent financed by the Federal Ministry of Education and Research and 10 percent by the state of Baden-Württemberg. The DKFZ is a member of the Helmholtz Association of German Research Centers.


Subscribe to our RSS-Feed.

to top
powered by webEdition CMS