Researchers identify previously unknown anti-cancer protein
The treatment options for cancer are extremely different depending on the type of tumor and the stage of the disease. In the case of liver cell cancer, the chances of recovery for those affected have so far often been rather poor, which is partly due to the often late diagnosis and secondly due to the limited therapeutic options. However, scientists have now discovered a protein that could be helpful in both early diagnosis and treatment of liver cell cancer.
The international research team led by Professor Michael N. Hall from the Biozentrum of the University of Basel has identified "a new anti-cancer protein". The protein LHPP prevents the unchecked proliferation of cancer cells in the liver. The protein is also suitable as a biomarker for the diagnosis and prognosis of liver cell cancer, according to the University of Basel. The scientists have published their research results in the journal "Nature".
Incidence of liver cancer is increasing
The frequency of liver cancer has risen steadily in recent years, according to the researchers. In Switzerland, for example, the number of illnesses has almost doubled in the past twenty years. Often, the chances of recovery for those affected are rather poor because the cancer - due to the lack of symptoms in the early stages - is discovered late and the liver is already severely damaged, the scientists report.
Crucial importance of tumor suppressors
"Liver tumors develop from pre-damaged cells that grow uncontrollably and multiply indefinitely," the experts explain. However, excessive cell growth is prevented by so-called tumor suppressors (special proteins). However, these anti-cancer proteins are often defective in the cancer cells. The now identified LHPP forms one of these tumor suppressors. In the current study, the researchers were able to demonstrate "that the loss of LHPP drives tumor growth and reduces the chance of survival of cancer patients."
More than 4,000 proteins examined
According to the University of Basel, the research team developed a mouse model for liver cell carcinoma in which they activated the growth protein mTOR in the liver. They then analyzed a total of more than 4,000 proteins and compared them in healthy and cancerous tissue. An enzyme has emerged as particularly promising in the course of the investigations - the histidine phosphatase LHPP, according to the University of Basel.
LHPP was absent from tumor samples
"It was very noticeable that LHPP is only found in healthy tissue and is completely absent in the tumor samples," emphasizes lead author Sravanth Hindupur in the press release from the university on the study results. In the animals to which the genetic information for LHPP was reinstalled, no tumors had arisen and their liver function was also preserved. "Similar to the mouse model, we were able to see markedly reduced LHPP levels in tumors of patients with liver cancer," Hindupur continues.
Better diagnosis and prognosis of the course of the disease possible?
The researchers also found that both the severity of the disease and life expectancy are directly related to the amount of LHPP. "If the anti-cancer protein is completely lost, cancer patients die on average two years earlier," reports the University of Basel. The protein would thus also be suitable as a biomarker for the diagnosis and prognosis of the course of the disease. LHPP forms a phosphatase, which removes all those phosphate groups attached to a histidine from proteins, the scientists explain the function of LHPP. Like all amino acids, histidine is one of the basic building blocks of proteins.
New level of tumor development made visible
So far, the so-called histidine phosphorylation of proteins "has hardly been researched because there were no suitable tools," the experts report. For the current investigations, however, "Tony Hunter from the Salk Institute in the USA provided new tools" with which "we could now make a whole new level of tumor development visible," emphasizes Hindupur. It had become clear that the lack of the anti-cancer protein LHPP leads to the proteins being phosphorylated beyond the normal level on the histidine. This promotes uncontrolled cell growth and thus the development of tumors. LHPP presumably also plays a role in other cancers, according to the scientists. (fp)