Cancer cells can now be specifically targeted by light.
Image credit: Malgorzata Borowiak, LMU Munich
The research co-authored by Oliver Thorn-Seshold, PhD, and Prof. Dirk Trauner, both from the Ludwig-Maximilians-Universitat, Munich, Germany. They sought to solve the problem of the severe side effects experienced by some users of widely prescribed chemotherapeutic drugs.
There are currently over 100 types of cancer currently identified, each classified by the cell that is affected. Different types of cancer very rarely behave similarly, hence the huge challenge facing patients and health care professionals to identify the best treatment.
Traditionally, chemotherapy drugs do not specifically target cancer cells, and so intersect with the function of normal cells, causing severe side effects such as heart and nerve damage. Due to this risk, the treatment can only be administered in relatively low doses and does not provide the best therapeutic benefit.
To overcome this challenge, scientists developed a method for optically controlling microtubule inhibitor drugs that are currently in clinical trials. Inhibitors interfere with the function of microtubules, components of the cell's skeleton that play a key role in cell proliferation, migration and survival.Researchers identified a fixed structural element required for a drug's biological activity and replaced this element with a flexible hinge that can swing open or shut in response to blue light.
Prof. Trauner describes the advantage of the technique:
"The upshot is that our compounds retain the powerful anticancer effects of existing microtubule inhibitors but add the bonus of tissue-specific localization."
The modified compounds, called "photostatins," are effective at inhibiting the proliferation and survival of cells targeted by light, but neighboring cells are unaffected. This technique can be used numerous times, making it suitable for long-term applications in both the clinic and lab.
The new development also opens the door for further research because the technique targets a critical microtubule subunit located in the cells of all plants and animals. This method may be adapted to study or treat a broad range of organisms or processes, or even potentially a broad range of diseases in humans.
Dr. Thorn-Seshold hopes the elimination of the unwanted side effects ensures "the new compounds will be able to be used in medicine at dosages that are truly therapeutic in tumors, thus achieving a much more effective therapy than currently possible."
In future clinical settings, scientists hope the technique can treat a range of conditions. Eye cancer patients can be treated wearing blue-tinted glasses and skin cancer with a bandage that delivers light. An implantable network of tiny LEDs that blink every few minutes to maintain the chemotherapeutic effect can be used for internal tumors.
Dr. Thorn-Seshold hopes the results will be an important step in the development of cancer treatment, he said:
"The field of photopharmacology is very young, so it may take some time for the pharmaceutical industry to recognize the value of compounds. Yet if our ongoing studies are successful, we will have a convincing proposition for further preclinical development, and we are committed to getting as far into real therapy as we can."