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MicroRNA manipulation in colorectal cancer cells: from laboratory to clinical application.

Aslam MI, Patel M, Singh B, Jameson JS, Pringle JH - J Transl Med (2012)

Bottom Line: Strategy based on restoration of silenced miRNAs or inhibition of over expressed miRNAs has opened a new area of research in cancer therapy.Restoration of normal equilibrium for cancer related miRNAs can result in inhibition of tumour growth, apoptosis, blocking of invasion, angiogenesis and metastasis.However, further work is needed on tissue specific delivery systems and strategies to avoid side effects.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Cancer Studies and Molecular Medicine, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester Royal Infirmary, P O Box 65, Leicester LE2 7LX, United Kingdom. mia7@leicester.ac.uk

ABSTRACT
The development of Colorectal Cancer (CRC) follows a sequential progression from adenoma to the carcinoma. Therefore, opportunities exist to interfere with the natural course of disease development and progression. Dysregulation of microRNAs (miRNAs) in cancer cells indirectly results in higher levels of messenger RNA (mRNA) specific to tumour promoter genes or tumour suppressor genes. This narrative review aims to provide a comprehensive review of the literature about the manipulation of oncogenic or tumour suppressor miRNAs in colorectal cancer cells for the purpose of development of anticancer therapies. A literature search identified studies describing manipulation of miRNAs in colorectal cancer cells in vivo and in vitro. Studies were also included to provide an update on the role of miRNAs in CRC development, progression and diagnosis. Strategy based on restoration of silenced miRNAs or inhibition of over expressed miRNAs has opened a new area of research in cancer therapy. In this review article different techniques for miRNA manipulation are reviewed and their utility for colorectal cancer therapy has been discussed in detail. Restoration of normal equilibrium for cancer related miRNAs can result in inhibition of tumour growth, apoptosis, blocking of invasion, angiogenesis and metastasis. Furthermore, drug resistant cancer cells can be turned into drug sensitive cells on alteration of specific miRNAs in cancer cells. MiRNA modulation in cancer cells holds great potential to replace current anticancer therapies. However, further work is needed on tissue specific delivery systems and strategies to avoid side effects.

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Related in: MedlinePlus

Figure illustrates the biogenesis of miRNAs in the cellular nucleous, its transport to the cytoplasm, and processing by Drosha and Dicer Enzymes. The figure also illustrates the RISC incorporation of miRNAs for functional activity in different pathways of translational inhibition or activation. In brief, miRNAs are mostly transcribed from intragenic or intergenic regions by RNA polymerase II into primary transcripts (pri-miRNAs) of variable length (1 kb- 3 kb). In the nucleus Pri-miRNA transcript is further processed by the nuclear ribo-nuclease enzyme ‘Drosha’ thereby resulting in a hairpin intermediate of about 70–100 nucleotides, called pre-miRNA. The pre-miRNA is then transported out of the nucleus by a transporting protein exportin-5. In the cytoplasm, the pre-miRNA is once again processed by another ribonuclease enzyme ‘Dicer’ into a mature double-stranded miRNA. Two strands of double stranded miRNA (miRNA/miRNA* complex) are separated by Dicer processing. After strand separation, mature miRNA strand (miRNA- also called the guide strand) is incorporated into the RNA-induced silencing complex (RISC), whereas the passenger strand, denoted with a star (miRNA*) is commonly degraded. This miRNA/RISC complex is responsible for miRNA function. If on miRNA cloning, or miRNA array, the passenger strand is found at low frequency (less than 15% of the guide strand) it is named miR*. However, if both passenger and guide strand are equal in distribution, then these two strands are named the 3p and 5p version of miRNA depending on their location to either 5' or 3' of the miRNA molecule. In this case both strands can potentially incorporate in position into the RISC complex and have a biological role [9-14]. The specificity of miRNA targeting is defined by Watson–Crick complementarities between positions 2 to 8 from the 5 primed end of the miRNA sequence with the 3′ untranslated region (UTR) of their target mRNAs. When miRNA and its target mRNA sequence show perfect complementarities, the RISC induces mRNA degradation. Should an imperfect miRNA–mRNA target pairing occur, translation into a protein is blocked [9,10]. Regardless of which of these two events occur, the net result is a decrease in the amount of protein encoded by the mRNA targets. Each miRNA has the potential to target a large number of genes (on average about 500 for each miRNA family). Conversely, an estimated 60% of the mRNAs have one or more evolutionarily conserved sequence that is predicted to interact with miRNAs [9,10,15]. miRNAs have been shown to bind to the open reading frame or to the 5′ UTR of the target genes and, in some cases, they have been shown to activate rather than to inhibit gene expression [16]. Researchers have also reported that miRNAs can bind to ribonucleoproteins in a seed sequence and a RISC-independent manner and then interfere with their RNA binding functions (decoy activity) [17]. MiRNAs can also regulate gene expression at the transcriptional level by binding directly to the DNA [18].
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Figure 1: Figure illustrates the biogenesis of miRNAs in the cellular nucleous, its transport to the cytoplasm, and processing by Drosha and Dicer Enzymes. The figure also illustrates the RISC incorporation of miRNAs for functional activity in different pathways of translational inhibition or activation. In brief, miRNAs are mostly transcribed from intragenic or intergenic regions by RNA polymerase II into primary transcripts (pri-miRNAs) of variable length (1 kb- 3 kb). In the nucleus Pri-miRNA transcript is further processed by the nuclear ribo-nuclease enzyme ‘Drosha’ thereby resulting in a hairpin intermediate of about 70–100 nucleotides, called pre-miRNA. The pre-miRNA is then transported out of the nucleus by a transporting protein exportin-5. In the cytoplasm, the pre-miRNA is once again processed by another ribonuclease enzyme ‘Dicer’ into a mature double-stranded miRNA. Two strands of double stranded miRNA (miRNA/miRNA* complex) are separated by Dicer processing. After strand separation, mature miRNA strand (miRNA- also called the guide strand) is incorporated into the RNA-induced silencing complex (RISC), whereas the passenger strand, denoted with a star (miRNA*) is commonly degraded. This miRNA/RISC complex is responsible for miRNA function. If on miRNA cloning, or miRNA array, the passenger strand is found at low frequency (less than 15% of the guide strand) it is named miR*. However, if both passenger and guide strand are equal in distribution, then these two strands are named the 3p and 5p version of miRNA depending on their location to either 5' or 3' of the miRNA molecule. In this case both strands can potentially incorporate in position into the RISC complex and have a biological role [9-14]. The specificity of miRNA targeting is defined by Watson–Crick complementarities between positions 2 to 8 from the 5 primed end of the miRNA sequence with the 3′ untranslated region (UTR) of their target mRNAs. When miRNA and its target mRNA sequence show perfect complementarities, the RISC induces mRNA degradation. Should an imperfect miRNA–mRNA target pairing occur, translation into a protein is blocked [9,10]. Regardless of which of these two events occur, the net result is a decrease in the amount of protein encoded by the mRNA targets. Each miRNA has the potential to target a large number of genes (on average about 500 for each miRNA family). Conversely, an estimated 60% of the mRNAs have one or more evolutionarily conserved sequence that is predicted to interact with miRNAs [9,10,15]. miRNAs have been shown to bind to the open reading frame or to the 5′ UTR of the target genes and, in some cases, they have been shown to activate rather than to inhibit gene expression [16]. Researchers have also reported that miRNAs can bind to ribonucleoproteins in a seed sequence and a RISC-independent manner and then interfere with their RNA binding functions (decoy activity) [17]. MiRNAs can also regulate gene expression at the transcriptional level by binding directly to the DNA [18].

Mentions: miRNAs are single-stranded, evolutionarily conserved, small (17–25 ribonucleotides) noncoding [8] RNA molecules. MiRNAs function as negative regulators of target genes by directing specific messenger RNA cleavage or translational inhibition through RNA induced silencing complex termed as RISC [9,10]. So far around fourteen hundred mature human miRNAs have been described in the Sanger miRBase version 17 (An international registry and database for miRNAs nomenclature, targets, functions and their implications in different diseases). Figure 1 illustrates the biogenesis and mechanism of action of miRNAs [11-18].


MicroRNA manipulation in colorectal cancer cells: from laboratory to clinical application.

Aslam MI, Patel M, Singh B, Jameson JS, Pringle JH - J Transl Med (2012)

Figure illustrates the biogenesis of miRNAs in the cellular nucleous, its transport to the cytoplasm, and processing by Drosha and Dicer Enzymes. The figure also illustrates the RISC incorporation of miRNAs for functional activity in different pathways of translational inhibition or activation. In brief, miRNAs are mostly transcribed from intragenic or intergenic regions by RNA polymerase II into primary transcripts (pri-miRNAs) of variable length (1 kb- 3 kb). In the nucleus Pri-miRNA transcript is further processed by the nuclear ribo-nuclease enzyme ‘Drosha’ thereby resulting in a hairpin intermediate of about 70–100 nucleotides, called pre-miRNA. The pre-miRNA is then transported out of the nucleus by a transporting protein exportin-5. In the cytoplasm, the pre-miRNA is once again processed by another ribonuclease enzyme ‘Dicer’ into a mature double-stranded miRNA. Two strands of double stranded miRNA (miRNA/miRNA* complex) are separated by Dicer processing. After strand separation, mature miRNA strand (miRNA- also called the guide strand) is incorporated into the RNA-induced silencing complex (RISC), whereas the passenger strand, denoted with a star (miRNA*) is commonly degraded. This miRNA/RISC complex is responsible for miRNA function. If on miRNA cloning, or miRNA array, the passenger strand is found at low frequency (less than 15% of the guide strand) it is named miR*. However, if both passenger and guide strand are equal in distribution, then these two strands are named the 3p and 5p version of miRNA depending on their location to either 5' or 3' of the miRNA molecule. In this case both strands can potentially incorporate in position into the RISC complex and have a biological role [9-14]. The specificity of miRNA targeting is defined by Watson–Crick complementarities between positions 2 to 8 from the 5 primed end of the miRNA sequence with the 3′ untranslated region (UTR) of their target mRNAs. When miRNA and its target mRNA sequence show perfect complementarities, the RISC induces mRNA degradation. Should an imperfect miRNA–mRNA target pairing occur, translation into a protein is blocked [9,10]. Regardless of which of these two events occur, the net result is a decrease in the amount of protein encoded by the mRNA targets. Each miRNA has the potential to target a large number of genes (on average about 500 for each miRNA family). Conversely, an estimated 60% of the mRNAs have one or more evolutionarily conserved sequence that is predicted to interact with miRNAs [9,10,15]. miRNAs have been shown to bind to the open reading frame or to the 5′ UTR of the target genes and, in some cases, they have been shown to activate rather than to inhibit gene expression [16]. Researchers have also reported that miRNAs can bind to ribonucleoproteins in a seed sequence and a RISC-independent manner and then interfere with their RNA binding functions (decoy activity) [17]. MiRNAs can also regulate gene expression at the transcriptional level by binding directly to the DNA [18].
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3539910&req=5

Figure 1: Figure illustrates the biogenesis of miRNAs in the cellular nucleous, its transport to the cytoplasm, and processing by Drosha and Dicer Enzymes. The figure also illustrates the RISC incorporation of miRNAs for functional activity in different pathways of translational inhibition or activation. In brief, miRNAs are mostly transcribed from intragenic or intergenic regions by RNA polymerase II into primary transcripts (pri-miRNAs) of variable length (1 kb- 3 kb). In the nucleus Pri-miRNA transcript is further processed by the nuclear ribo-nuclease enzyme ‘Drosha’ thereby resulting in a hairpin intermediate of about 70–100 nucleotides, called pre-miRNA. The pre-miRNA is then transported out of the nucleus by a transporting protein exportin-5. In the cytoplasm, the pre-miRNA is once again processed by another ribonuclease enzyme ‘Dicer’ into a mature double-stranded miRNA. Two strands of double stranded miRNA (miRNA/miRNA* complex) are separated by Dicer processing. After strand separation, mature miRNA strand (miRNA- also called the guide strand) is incorporated into the RNA-induced silencing complex (RISC), whereas the passenger strand, denoted with a star (miRNA*) is commonly degraded. This miRNA/RISC complex is responsible for miRNA function. If on miRNA cloning, or miRNA array, the passenger strand is found at low frequency (less than 15% of the guide strand) it is named miR*. However, if both passenger and guide strand are equal in distribution, then these two strands are named the 3p and 5p version of miRNA depending on their location to either 5' or 3' of the miRNA molecule. In this case both strands can potentially incorporate in position into the RISC complex and have a biological role [9-14]. The specificity of miRNA targeting is defined by Watson–Crick complementarities between positions 2 to 8 from the 5 primed end of the miRNA sequence with the 3′ untranslated region (UTR) of their target mRNAs. When miRNA and its target mRNA sequence show perfect complementarities, the RISC induces mRNA degradation. Should an imperfect miRNA–mRNA target pairing occur, translation into a protein is blocked [9,10]. Regardless of which of these two events occur, the net result is a decrease in the amount of protein encoded by the mRNA targets. Each miRNA has the potential to target a large number of genes (on average about 500 for each miRNA family). Conversely, an estimated 60% of the mRNAs have one or more evolutionarily conserved sequence that is predicted to interact with miRNAs [9,10,15]. miRNAs have been shown to bind to the open reading frame or to the 5′ UTR of the target genes and, in some cases, they have been shown to activate rather than to inhibit gene expression [16]. Researchers have also reported that miRNAs can bind to ribonucleoproteins in a seed sequence and a RISC-independent manner and then interfere with their RNA binding functions (decoy activity) [17]. MiRNAs can also regulate gene expression at the transcriptional level by binding directly to the DNA [18].
Mentions: miRNAs are single-stranded, evolutionarily conserved, small (17–25 ribonucleotides) noncoding [8] RNA molecules. MiRNAs function as negative regulators of target genes by directing specific messenger RNA cleavage or translational inhibition through RNA induced silencing complex termed as RISC [9,10]. So far around fourteen hundred mature human miRNAs have been described in the Sanger miRBase version 17 (An international registry and database for miRNAs nomenclature, targets, functions and their implications in different diseases). Figure 1 illustrates the biogenesis and mechanism of action of miRNAs [11-18].

Bottom Line: Strategy based on restoration of silenced miRNAs or inhibition of over expressed miRNAs has opened a new area of research in cancer therapy.Restoration of normal equilibrium for cancer related miRNAs can result in inhibition of tumour growth, apoptosis, blocking of invasion, angiogenesis and metastasis.However, further work is needed on tissue specific delivery systems and strategies to avoid side effects.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Cancer Studies and Molecular Medicine, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester Royal Infirmary, P O Box 65, Leicester LE2 7LX, United Kingdom. mia7@leicester.ac.uk

ABSTRACT
The development of Colorectal Cancer (CRC) follows a sequential progression from adenoma to the carcinoma. Therefore, opportunities exist to interfere with the natural course of disease development and progression. Dysregulation of microRNAs (miRNAs) in cancer cells indirectly results in higher levels of messenger RNA (mRNA) specific to tumour promoter genes or tumour suppressor genes. This narrative review aims to provide a comprehensive review of the literature about the manipulation of oncogenic or tumour suppressor miRNAs in colorectal cancer cells for the purpose of development of anticancer therapies. A literature search identified studies describing manipulation of miRNAs in colorectal cancer cells in vivo and in vitro. Studies were also included to provide an update on the role of miRNAs in CRC development, progression and diagnosis. Strategy based on restoration of silenced miRNAs or inhibition of over expressed miRNAs has opened a new area of research in cancer therapy. In this review article different techniques for miRNA manipulation are reviewed and their utility for colorectal cancer therapy has been discussed in detail. Restoration of normal equilibrium for cancer related miRNAs can result in inhibition of tumour growth, apoptosis, blocking of invasion, angiogenesis and metastasis. Furthermore, drug resistant cancer cells can be turned into drug sensitive cells on alteration of specific miRNAs in cancer cells. MiRNA modulation in cancer cells holds great potential to replace current anticancer therapies. However, further work is needed on tissue specific delivery systems and strategies to avoid side effects.

Show MeSH
Related in: MedlinePlus