In laboratory studies, the researchers isolated a protein, caveolin-1, showing that in breast cancer cells this protein can enhance cell death in response to the use of Taxol, one of two taxane chemotherapy drugs used to treat advanced breast and ovarian cancer. But in order to work, they found the protein needs to be "switched on," or phosphorylated. The results were reported in the current (February 23) issue of the Journal of Biological Chemistry.
Their finding suggests it may eventually be possible to test individual breast cancer patients for the status of such molecular markers as caveolin-1 in their tumors to determine the efficacy-to-toxicity ratio for Taxol, said the study’s first author, postdoctoral fellow Ayesha Shajahan, Ph.D., of Lombardi Comprehensive Cancer Center at Georgetown.
"Because breast tumors are not all the same, it is important to know the cancer’s molecular makeup in order to increase the efficiency, and lower the toxicity, of chemotherapy drugs, and this work takes us some steps forward in this goal," she said. "It also offers insights into why some breast cancer cells can become resistant to therapeutic drugs."
Additionally, the study identifies caveolin-1 as a new molecular target for increasing the efficacy of taxanes, according to the study’s lead investigator, Robert Clarke, Ph.D., D.Sc., a Professor of Oncology and Physiology & Biophysics. "This is important because the taxanes are active drugs in breast cancer, so now that we know caveolin-1 is a new mechanism to explain how these drugs kill breast cancer cells, we can potentially take advantage of that fact to improve these agents."
The taxanes are Taxol (also known as paclitaxel) and Taxotere (docetaxel). Taxol was originally derived from the Pacific yew tree, and Taxotere is a semi-synthetic version of Taxol with slight chemical changes. These drugs stabilize a cell’s "microtubules," the road-like protein structures that send chemical signals to all parts of the cell, and which must be flexible if a cell is to divide. Taxanes lock these structures into place, not allowing them to change when the cell begins to divide - which is necessary for tumor growth. Research has also indicated that the drugs induce programmed cell death (apoptosis) in cancer cells by inactivating an "apoptosis stopping protein" called BCL2, thus stopping it from inhibiting cell death.
Caveolin-1 is a protein that is found in most cells under normal conditions and it is involved in an array of cellular events that ranges from vesicle trafficking to cell migration. It is, therefore, as a key regulator of multiple events within the cell.
In cancer, the expression level of caveolin-1 can vary depending on cell type. However, the precise role of caveolin-1 in cancer has been controversial: whether it acts as a suppressor or facilitator of tumor formation depends on the cell type. In human breast cancer, caveolin-1 has been known to act as a tumor suppressor since caveolin-1 expression is down-regulated during the primary stages of breast cancer. More recent studies indicate that that caveolin-1 expression is increased in more aggressive types of breast cancer.
Under the mentorship of Clarke, Shajahan sought to determine factors that regulate expression and function of caveolin-1 in the breast. In this study, the researchers show that in their breast cancer cell model that phosphorylated caveolin-1 increased cell death by activating other key regulators vital to both breast cancer progression and cell death, including BCL2, the same protein that Taxol works on; p21, which controls cell cycle progression; and the tumor suppressor p53.
If caveolin-1 isn’t phosphorylated, breast cancer cells appear to be resistant to Taxol treatment, the researchers conclude. "Thus, this study opens an area of investigation in our lab that will concentrate on understanding how this multi-tasking protein can serve as a marker for chemotherapeutic drug efficacy," Shajahan said.
Laura Cavender | EurekAlert!
A novel socio-ecological approach helps identifying suitable wolf habitats
17.02.2017 | Universität Zürich
New, ultra-flexible probes form reliable, scar-free integration with the brain
16.02.2017 | University of Texas at Austin
Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...
The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.
The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...
Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...
Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".
Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...
13.02.2017 | Event News
10.02.2017 | Event News
09.02.2017 | Event News
17.02.2017 | Medical Engineering
17.02.2017 | Medical Engineering
17.02.2017 | Health and Medicine