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Gene discovery

Scientists find the mutated gene linked to the progression of colon cancer that could lead to diagnostic tests to target it.
PTI | By ANI, Washington
UPDATED ON MAR 13, 2004 11:59 AM IST


A new study has found mutation in a gene linked to the progression of colon and other cancers, that could lead to new therapies and diagnostic tests that target this gene.


Johns Hopkins Kimmel Cancer Center and Howard Hughes Medical Institute conducted the study, published online in the latest issue of Science.


The gene in which the mutations have been found, called PIK3CA, is part of a family of genes encoding lipid kinases, enzymes that modify fatty molecules and direct cells to grow, change shape and move. Although scientists have been studying the biochemical properties of this family of genes for more than a decade, until now, no study revealed that they were mutated in cancer.


Kinases have been the focus of recent drug development strategies, with some kinase-inhibiting compounds, such as Gleevec and Herceptin, already being used clinically to inhibit tumour growth.


"These findings open the door to developing specific therapies that may prove useful for the treatment of cancers with mutations in PIK3CA," said Victor Velculescu, assistant professor of oncology and senior author of the research.


In their current experiments, the scientists sequenced the molecular code of the genes in this lipid kinase family and found mistakes in the nucleotides, or DNA building blocks, in one particular gene, called PIK3CA.


The investigators demonstrated that the mutations increase PIK3CA kinase activity, which can start a cascade of cellular events that spark a normal cell to grow uncontrollably and become cancerous.


"We envision future cancer therapy as personalized, based on gene mutations in each patient's tumor. This kind of information, gleaned from sequencing a patient's tumor, means drugs could be targeted to just the right molecular pathway at just the right time and potentially be more effective with fewer side effects", noted Velculescu.


Most of the PIK3CA mutations described in the current paper are located in two DNA cancer "hot spots," thus making molecular diagnostic tests possibly easier to develop. "These mutations, added to a panel of existing markers for colon cancer developed in our laboratory, could help find cancers that would otherwise go undetected," added Yardena Samuels, postdoctoral fellow and first author of the study.


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