Knockdown of RPL9 expression inhibits colorectal carcinoma growth via the inactivation of Id-1/NF-κB signaling axis

Abstract

Ribosomal protein L9 (RPL9), a component of the 60S subunit for protein synthesis, is upregulated in human colorectal cancer. In the present study, we investigated whether RPL9 gained extraribosomal function during tumorigenesis and whether targeting of RPL9 with small interfering (si) RNA could alter the course of colorectal cancer progression. Our results showed that siRNA knockdown of RPL9 suppresses colorectal cancer (CRC) cell growth and long-term colony formation through an increase in sub-G1 cell population and a strong induction of apoptotic cell death. To obtain insights into the molecular changes in response to RPL9 knockdown, global changes in gene expression were examined using RNA sequencing. It revealed that RPL9-specific knockdown led to dysregulation of 918 genes in HCT116 and 3178 genes in HT29 cells. Among these, 296 genes showed same directional regulation (128 upregulated and 168 downregulated genes) and were considered as a common RPL9 knockdown signature. Particularly, we found through a network analysis that Id-1, which is functionally associated with activation of NF-κB and cell survival, was commonly downregulated. Subsequent western blot analysis affirmed that RPL9 silencing induced the decrease in the levels of Id-1 and phosphorylated IκBα in both HCT116 and HT29 cells. Also, the same condition decreased the levels of PARP-1 and pro-caspase-3, accelerating apoptosis. Furthermore, inhibition of RPL9 expression significantly suppressed the growth of human CRC xenografts in nude mice. These findings indicate that the function of RPL9 is correlated with Id-1/NF-κB signaling axis and suggest that targeting RPL9 could be an attractive option for molecular therapy of colorectal cancer.

A study of the impact of inhibitors of DNA binding‐1 on proliferation and migration in human colon carcinoma cells

“…12 Furthermore, it has been found in gastric cancer and pancreatic cancer cells that the Id-reverse target-nuclear factor κB (NF-κB) pathway is activated to promote the expression of Bcl-2, inhibit the TNF-ɑ pathway, decrease the expression level of caspase-3, and inhibit tumor cell death. [13][14][15] In this present study, an interference sequence of Id-1 was introduced into SW480 and HT-29 colon cancer cells, and it was found through MTT detection that proliferation began to decrease in the inhibition groups from the third day, and the growth inhibition in the inhibition groups was obvious from the fourth day. This reveals that the proliferation ability of cells significantly decreased in the inhibition groups, proving that Id-1 can promote colon cancer cell proliferation.…”

“…In addition, it has been found in bone cell cancer that Id‐1 activates cell growth and promotes cell proliferation by activating the MAPK of Raf‐1 . Furthermore, it has been found in gastric cancer and pancreatic cancer cells that the Id‐reverse target‐nuclear factor κB (NF‐κB) pathway is activated to promote the expression of Bcl‐2, inhibit the TNF‐ɑ pathway, decrease the expression level of caspase‐3, and inhibit tumor cell death . In this present study, an interference sequence of Id‐1 was introduced into SW480 and HT‐29 colon cancer cells, and it was found through MTT detection that proliferation began to decrease in the inhibition groups from the third day, and the growth inhibition in the inhibition groups was obvious from the fourth day.…”

“… The process of direct invasion includes the decrease of adhesion of tumor cells and the degradation of the basement membrane and extracellular matrix. Previous studies on this aspect have proven that through promoting the expression of genes such MMP‐2 and MMP‐9, Id‐1 can promote damage to structures of the basement membrane and accelerate the infiltration of tumors in colorectal cancer tissues . Furthermore, Id‐1 can induce the proliferation of endothelial cells in blood vessels and promote the formation of blood capillaries and lymphatic microvessels through increasing expression of vascular endothelial growth factor (VEGF), providing the necessary material foundation for the infiltration and metastasis of tumors .…”

“…Previous studies on this aspect have proven that through promoting the expression of genes such MMP-2 and MMP-9, Id-1 can promote damage to structures of the basement membrane and accelerate the infiltration of tumors in colorectal cancer tissues. 18,19 Furthermore, Id-1 can induce the proliferation of endothelial cells in blood vessels and promote the formation of blood capillaries and lymphatic microvessels through increasing expression of vascular endothelial growth factor (VEGF), providing the necessary material foundation for the infiltration and metastasis of tumors. 20,21 The results of the Transwell chamber and Matrigel experiments revealed that the migration and invasion abilities of SW480 and HT-29 human colonic cancer cells with the interfering sequence of Id-1 were significantly lower than that in the blank groups and blank load groups, proving that the overexpression of Id-1 could promote the invasion and metastasis of tumors.…”

Tropomyosin isoforms have specific effects on the transcriptome of undifferentiated and differentiated B35 neuroblastoma cells

“…Of these GO terms, ribosomal, RNA, and ubiquitin related are among the pathways holding the highest statistical significance. Ribosomal proteins are most commonly known to be involved in protein synthesis but have also been shown to exert extraribosomal functions including immune signaling and development of various cell types as well as being implicated in various cancers including glioblastoma, gastrointestinal, prostate, and lung . In this study, expression levels of many genes, encoding ribosomal proteins (Rp), were found to be differentially regulated in both Tpm1.12‐ and Tpm2.1‐overexpressing cells including Rpl9, Rpl13, Rpl19, and Rpl22 .…”