miR-21 and let-7 are two of the most studied microRNAs (miRNAs), as the former is the most frequently
upregulated and the latter is the most frequently down-regulated in cancer. In this short essay, we examine the convergence
of miR-21 and let-7 in two major cancer pathways: Ras and NF-κB. miR-21 suppresses multiple targets to enhance
the oncogenic action of Ras, while let-7 is a direct negative regulator of the Ras gene family. let-7 is proposed to repress
the activation of NF-κB through down-regulation of Ras and IL-6, while miR-21 is demonstrated to enhance NF-κB activation
by down-regulating Pten and thereby increasing the activity of Akt, a kinase known to promote the NF-κB pathway.
Therefore, miR-21 and let-7 contravene each other in cancer and simultaneous targeting of both is an attractive
therapeutic strategy against cancers exhibiting both Ras mutations and constitutive NF-κB activation.
Keywords: MicroRNA, Cancer, miR-21, let-7, Ras, NF-kB, oncogenic action, apoptosis, pathobiological, phylogenetic.
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Published on: 19 September, 2012
Page: [65 - 69]