miR-21; a tiny messenger that can help predict colorectal cancer relapse

This study investigated if miR-21 levels can predict cancer relapse in colorectal cancer patients.

MicroRNA’s are small messengers that help regulate the levels of genes. Recent studies have shown that one particular microRNA, miR-21, is associated with the progression of some cancers. Certain proteins produced in the body are also involved in cancer progression and the spread of cancer to distant organs, for example, E-cadherin and metastasis-associated protein1. Decreases in E-cadherin are linked to increased invasion and spread of various cancers. Increases in metastasis-associated protein1 are linked with increased progression and spread of cancer.

It is not known whether miR-21 is linked to levels of E-cadherin and metastasis-associated protein1. It is also unclear whether miR-21 levels can predict cancer progression in colorectal cancer patients.

This study included 277 patients with T3-4a colorectal cancer. T3-4a indicates that the cancer has grown into or through the outer layer of the intestine but has not invaded nearby tissues or organs. All patients were treated with curative surgery and none received chemotherapy or radiotherapy before surgery. E-cadherin, metastasis-associated protein 1 and miR-21 were measured in bowel samples.

27.4% of patients had high levels of miR-21 in their colon or rectal samples. High miR-21 was directly linked to low levels of E-cadherin and high levels of metastasis-associated protein1. Colon cancer patients with high levels of miR-21 had a 2.5 fold higher risk of cancer relapse than patients with low levels. However, there was no link between miR-21, E-cadherin or metastasis-associated protein 1 and patient survival.

Overall, there was also no increased risk of cancer relapse or worse survival in rectal cancer patients with high levels of miR-21. However, when only patients with stage II cancer (no cancer in the lymph nodes) were analyzed, both colon and rectal cancer patients with high miR-21 had a significantly increased risk of relapsing.

The study concluded that stage II colorectal cancer patients and colon cancer patient with high levels of miR-21 have a higher rate of the cancer relapse. The authors suggested that these patients should be considered for more intensive treatment.