Photo/IllutrationShingo Dan, vice chief of molecular pharmacology at the Cancer Chemotherapy Center of the Japanese Foundation for Cancer Research in Tokyo’s Koto Ward (Tsuyoshi Kawamura)

Through experiments with mice, researchers confirmed that a newly-discovered chemical compound inhibits the proliferation of lung cancer cells previously resistant to existing anticancer drugs.

The researchers, most of them with the Japanese Foundation for Cancer Research in Tokyo’s Koto Ward and Tokyo University of Science, found that the substance suppresses the proliferation of cancer cells through a different mechanism from conventional agents.

The team intends to use the compound to develop a new anticancer drug.

“(The chemical compound) could be used to develop an anticancer agent that works through a new mechanism,” said Shingo Dan, vice chief of molecular pharmacology at the foundation's Cancer Chemotherapy Center.

“We will make improvements and confirm whether it is also useful for other types of cancer,” he said.

More than 70,000 people die of lung cancer in Japan annually, 30 percent of whom have genetic abnormalities in their EGFR gene. The mutated gene produces a protein associated with the proliferation of cancer cells.

Although Iressa and other molecular target drugs inhibit the activity of the protein, individuals who receive such agents for a year or so develop a tolerance for the drugs, rendering them ineffective.

A new drug called Tagrisso has proved useful in treating tumors resistant to existing agents. It gained official approval in Japan in 2016. Patients taking Tagrisso for a certain period can develop a tolerance and how to deal with Tagrisso-resistant tumors has not been established.

Dan and his colleagues studied an artificially made chemical compound that inhibits the function of the Golgi body, which transports intracellular proteins, to prevent cancer cells from proliferating.

Many conventional molecular target drugs react with proteins on the cell surface associated with the proliferation of cancer cells.

Adding the compound to human lung cancer cells associated with EGFR gene mutations is helpful in inhibiting the proliferation of tumor cells, the researchers found.

They also transplanted cancer cells tolerant to Tagrisso into mouse lungs to compare the size of tumors after three weeks.

While tumors swelled to three times their initial size in untreated and Tagrisso-treated mice, others did not change significantly in mice that were given the compound, according to the researchers.