Families of microRNAs Expressed in Clusters Regulate Cell Signaling in Cervical Cancer

Abstract

Tumor cells have developed advantages to acquire hallmarks of cancer like apoptosis resistance, increased proliferation, migration, and invasion through cell signaling pathway misregulation. The sequential activation of genes in a pathway is regulated by miRNAs. Loss or gain of miRNA expression could activate or repress a particular cell axis. It is well known that aberrant miRNA expression is well recognized as an important step in the development of cancer. Individual miRNA expression is reported without considering that miRNAs are grouped in clusters and may have similar functions, such as the case of clusters with anti-oncomiRs (23b~27b~24-1, miR-29a~29b-1, miR-29b-2~29c, miR-99a~125b-2, miR-99b~125a, miR-100~125b-1, miR-199a-2~214, and miR-302s) or oncomiRs activity (miR-1-1~133a-2, miR-1-2~133a-1, miR-133b~206, miR-17~92, miR-106a~363, miR183~96~182, miR-181a-1~181b-1, and miR-181a-2~181b-2), which regulated mitogen-activated protein kinases (MAPK), phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K), NOTCH, proteasome-culling rings, and apoptosis cell signaling. In this work we point out the pathways regulated by families of miRNAs grouped in 20 clusters involved in cervical cancer. Reviewing how miRNA families expressed in cluster-regulated cell path signaling will increase the knowledge of cervical cancer progression, providing important information for therapeutic, diagnostic, and prognostic methodology design.

Keywords: cell signaling pathways; cervical cancer; clusters; families of miRNAs.

Figure 1

Regulation of MAPK, PI3K-AKT, and G2-M checkpoint by members of the family miR-125 and members of miR-let-7c~99a, miR-125a~let-7e~99b, miR-100~let-7a-2, and miR-206~133b clusters in cervical cancer. MAPK cell signaling is triggered by MEK-1 activation via TRIB2 and HOXA1 conducing to ERK1/2 phosphorylation, thereby provoking apoptosis reduction and inducing proliferation, migration, and invasion. This pathway is regulated by downregulation of TRIB2 and HOXA1 by the family miR-99 clustered in miR-let-7c~99a, miR-125a~let-7e~99b, and miR-100~let-7a-2. The members of these clusters are diminished in cervical cancer. MST2 inhibits Raf-1 and activates LAST2/YAP, reducing Ras-MEK-ERK activation, thus diminishing proliferation and inducing apoptosis, respectively. The oncomiR-133b from the cluster miR-133b~206 inhibits the tumor suppressor MST2. As well as CDC42 and RhoA that in turn inactivates Plexin B1 and PTEN increasing PI3K-PDK1-AKT-mTOR signaling, thus augmenting translation. MiR-125a from the cluster miR-125a~let-7e~99b counteracts the effect of miR-133b through the downregulation of PIK3CD, inhibiting PI3K-PDK1-AKT-mTOR signaling. The family miR-99 reduces mTOR protein expression, having an opposite effect to the miR-206~133b cluster. The cell cycle is arrested by DNA damage via ATM and ATR activation consecutively by the activation of Chk1/2 blocking CDC25 hampering CDK1 stopping transition from G2 to M. ATM and ATR prevent Bora activation conducing to Aurora A, PlK1 and MDM2 inactivation, thereby stabilizing p53 and activating miR-34 family transcription. Also, p53 is activated directly by Chk1/2, ATR, and ATM. In cervical cancer PlK1 is upregulated because miR-100 from the cluster miR-100~let-7a-2 is downregulated, promoting MDM2 increase and contributing to p53 decrease, with a concomitant miR-34 family shrink increasing protein translation, proliferation, and apoptosis reduction. In bold are the miRNAs with effect on genes with validated experimental data.

Figure 2

Regulation of CUL5, JAG-NOTCH, TNKS2, and PTEN-PI3K-AKT cell signaling by members of miR-17~92 and miR-106a~363 clusters in cervical cancer. E3 ubiquitin ligase complexes formed by CUL5-E2-SOCS-JAK2/3 and CUL1-skp1-skip2-E47-E2 are activated by Abs2 and SOCS interchange potentiated through JAG1-NOTCH axis. The cell signaling of GS3K-catenin-APC-AXIN-1-TCF/LEF is activated by AXIN-1 inhibition, which triggers the JAG1-NOTCH pathway, which in turn accelerates the interchange of SOCS by Abs2. Additionally, CUL1-skp1-skip2-E47-E2 is activated by phosphorylation of E47 via Ras-Raf-MEK-1-ERK1/2. The miR-19a and miR-19b grouped in the clusters miR17~92 and miR106a~363 downregulated CUL5, increasing proliferation, migration, and invasion and diminishing apoptosis. MiR-20a, a member of the cluster miR17~92, increases TNK2 expression that in turn inhibits AXIN-1, activating TCF/LEF, inducing JAG1-NOTCH1 signaling. Another member of the clusters miR17~92 and miR106a~363, miR-92, hinders PTEN expression, supporting PI3K-PDK1-AKT1 signaling thereby spreading proliferation, migration, invasion, and constraining apoptosis. In bold are the miRNAs with effect on genes with validated experimental data.

Figure 3

Regulation of JAG1-NOTCH1-uPA, Cyclin D-CDK4/6-p21-p27, and PI3K-PDK1-AKT1 cell signaling by members of the miR-23b~27b~24-1, miR-29a~29b-1, miR-29b-2~29c, miR17~92, miR183~96~182, and miR-302s clusters. MiR-34a, a member of the miR-34 family, downregulates JAG1 and NOCTH1 expression. JAG1 is activated by uPA inducing ECM reorganization via plasminogen-plasmin-MMP, inducing the hallmarks of cancer. Protein expression of uPA is decreased by miR-23b, a member of the cluster 23b~27b~24-1. The complex cyclin D-CDK4/6 phosphorylates RB inducing the liberation of E2F, favoring c-Myc, c-Fos and COX-2 transcription provoking cellular division. Cellular division progression is regulated by the inhibition of cyclin D via the miR-302s cluster and CDK4/6 through p18Ink4c, p21, and p27. The PI3K-PDK1-AKT1 axis decreases p21 and p27 protein expression, delivering CDK4/6 to be complexed with cyclin D. This signaling pathway is regulated by the downregulation of AKT due to the miR-302s cluster increasing p21 and p27 proteins, thereby inhibiting the complex cyclin D-CDK4/6. CDK4/6 is inhibited by p18Ink4c, which in turn is downregulated by miR-34a, inducing apoptosis and causing proliferation to diminish. Another point of control is given by the miR-29a~29b-1 cluster hindering CDK4/6, which provokes inhibition of the complex cyclin D-CDK4/6. YY-1, a target of the cluster miR-29a~29b-1, induces transcription of c-Myc in the absence of this cluster common in cervical cancer. Cell cycle continuity is dependent on the levels and the complex formed of cyclin D-CDK4/6 and cyclin E-CDK4/6. FOXO1 could directly hinder CDK4/6, thus impeding the formation and activation of the complex cyclin D-CDK4/6 and cyclin E-CDK4/6 and indirectly via p27. Cyclin D is indirectly upregulated by miR-182, one member of the cluster miR183~96~182, through FOXO1 downregulation conducing to proliferation, migration, invasion, and apoptosis induction. These cellular processes are enhanced via FOXO1 phosphorylation by PI3K-PDK1-AKT, which is recognized by skp2, a subunit of the skip1/cul1/F-box ubiquitin protein complex, targeting it to degradation via proteasomes. MiR-92 diminishes the expression of PTEN, triggering PI3K-PDK1-AKT signaling, which is conducive to FOXO1 reduction. In bold are the miRNAs with effect on genes with validated experimental data.

Figure 4

Regulation of AC-PKA-smac-caspase3 and PKC cell signaling by members of miR-181a-1~181b-1 and miR-181a-2~181b-2 clusters. Adenylyl cyclase (AC) induces PKA activation, generating CREB phosphorylation, which turns on smac/Diablo, causing caspase 3 activation. In addition, PKC activates caspase 3 and caspase 7. miR-181b, localized in clusters miR-181a-1~181b-1 and miR-181a-2~181b-2, downregulates AC; miR-181a also inhibits PKC protein expression. In bold are the miRNAs with effect on genes with validated experimental data.

Figure 5

Regulation of Bcl-12l2-Bax-CASPS, MST1-MEK-4/7-JNK-1-MSK2, MST1-MEK-3-p38-MSK1, PI3K-PDK1-AKT, and Ras-Raf-MEK1-ERK1/2 cell signaling by the miR-214~199a-2 cluster. The anti-oncomiR-214 from the cluster miR-214~199a-2 promotes apoptosis by downregulation of Bcl-12-l2, permitting Bax activation with a consequent activation of caspases 9, 8, and 3. Furthermore, miR-214 inhibits JNK1 and MEK3, participants of cell signaling MST1-MEK-4/7-JNK-1-MSK2 and MST1-MEK-3-p38-MSK1, respectively. In addition, miR-214 controls MAPK activation by the downregulation of Plexin-B1, which in contact with Sema 4D activates RhoA, which then activates Raf-1 triggering MEK-1 and ERK1/2 phosphorylation together with PI3K-PIP3-PDK1-AKT, promoting the hallmarks of cancer. In bold are the miRNAs with effect on genes with validated experimental data.