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Two Micro RNA’s That Trigger Tumors’ Identified
January 30, 2008 at 8:41 PM
Genetics & Stem Cells News
When the researchers established metastasis-inducing properties of the miRNAs, they started searching for their target genes in MCF-7 cells.
After many experiments, the researchers narrowed their search down to a gene called CD44, containing genetic instructions for a common cell surface receptor molecule.
CD44 is found in most cell types and affects inter-cell as well as intra-cell interactions involving their microenvironments. It may also inhibit tumor metastasis.
It was discovered that on downregulating CD44, non-metastatic MCF-7 cells became metastatic.
The researchers found that when they injected MCF-7 cells without CD44 into immunodeficient mice, the mice developed bone and lung tumors, while mice receiving MCF-7 cells with CD44 did not.
“We found that miR-373 and miR-520c interfered with the expression of CD44 in MCF-7 cells. We think there are additional targets involved, but our results suggest that these miRNAs promote cell metastasis at least in part by limiting the expression of CD44,” said Huang.
At the final level of the study, the scientists examined 11 pairs of primary and metastatic breast cancer tissue samples from cancer patients. It was discovered that metastatic tumors taken out from lymph nodes contained more miR-373 than the primary breast tumor from the same patient.
In another study of 72 human primary breast tumors, the scientists found higher mean expression of miR-373, and lower mean expression of CD44, in primary tumors from patients whose cancer had spread to their lymph nodes, as compared to patients whose tumors had not spread.
Huang said that such findings indicate that miR-373 can potentially become an important early biomarker for metastatic breast cancer.
“As far as we know, miR-373 is not expressed in normal tissue. So if we detect miR-373 in lymph nodes when a patient’s breast tumor is removed, it would indicate that cancer cells have spread and the patient will need more aggressive therapy,” said Huang.
Source-ANI
SPH/M
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