Opiates to Mitigate could Promote Cancer Development
Opioids used in the treatment of cancer may promote its development, according to two studies of University Medical Center in Chicago.
The research results are made public at a forum held in Boston (United States) with the participation of the American Association for Cancer Research, National Cancer Institute of the United States and the European Organization for Research and
Although morphine has been the standard treatment for postoperative and chronic pain in cancer for two centuries, an increasing number of studies show that opiate-based painkillers can stimulate the growth and spread of cancer cells.
Two new studies show how the protection of lung cancer cells compared to opiates reduces proliferation, invasion and migration both in cell cultures in vitro and in mice.
Explains Patrick A. Singleton, “If confirmed clinically, this could change how we practice our surgical anesthesia in cancer patients. This also suggests possible new applications of this new class of drugs that could be explored.”
The researchers began a series of studies to examine many of the peripheral effects of opioids and the potential benefits of blocking these effects.
In laboratory studies, morphine may directly promote tumor cell proliferation and inhibit the immune response. The researchers found that opioids also promote angiogenesis, the growth of new blood vessels, and decreases the functioning of the brain barrier, effects that may worsen diseases involving vascular loss, including acute lung injury in experimental models .
According to researchers, surgical facilities, the lowest functioning barrier could facilitate the tumors invade the tissue and spread to distant sites. In addition, the increased angiogenesis helps cancers to proliferate in a new location.
In their studies, researchers focused on opioid receptors as regulators of tumor growth and metastasis and examined the ability of the drug metilnatrexona (MNTX) to mitigate these effects. The MNTX, approved by U.S. authorities in 2008, blocking side effects of morphine but does not interfere with its effects on pain, focusing on the brain.
The researchers used two different models of small cell lung cancer and showed that MNTX inhibited the effects of opioids that promote tumors. In a study using bronchoalveolar carcinoma cells and oncogenic signals MNTX blocked and prevented the proliferation and migration of tumor cells.
In another study, which used cells from Lewis lung carcinoma, mice without the mu opioid receptor did not develop tumors that did develop the mice that were injected with cancer cells.
The researchers then showed that MNTX reduced the proliferation of cancer cells by about 90 percent in normal mice. This also prevented the invasion of cultured cells and tumor growth and metastasis in mice. The authors conclude that opioid receptors promote growth, angiogenesis and tumor metastasis in Lewis lung cancer and that MNTX attenuates these oncogenic effects
