REVIEW article

Front. Cell Dev. Biol., 04 October 2021

Sec. Molecular and Cellular Oncology

Volume 9 - 2021 | https://doi.org/10.3389/fcell.2021.741684

A Review on the Role of Small Nucleolar RNA Host Gene 6 Long Non-coding RNAs in the Carcinogenic Processes

  • 1. Department of Medical Genetics, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran

  • 2. Men’s Health and Reproductive Health Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran

  • 3. Skull Base Research Center, Loghman Hakim Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran

  • 4. Department of Critical Care Medicine, Imam Hossein Medical and Educational Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran

Abstract

Being located on 17q25.1, small nucleolar RNA host gene 6 (SNHG16) is a member of SNHG family of long non-coding RNAs (lncRNA) with 4 exons and 13 splice variants. This lncRNA serves as a sponge for a variety of miRNAs, namely miR-520a-3p, miR-4500, miR-146a miR-16–5p, miR-98, let-7a-5p, hsa-miR-93, miR-17-5p, miR-186, miR-302a-3p, miR-605-3p, miR-140-5p, miR-195, let-7b-5p, miR-16, miR-340, miR-1301, miR-205, miR-488, miR-1285-3p, miR-146a-5p, and miR-124-3p. This lncRNA can affect activity of TGF-β1/SMAD5, mTOR, NF-κB, Wnt, RAS/RAF/MEK/ERK and PI3K/AKT pathways. Almost all studies have reported oncogenic effect of SNHG16 in diverse cell types. Here, we explain the results of studies about the oncogenic role of SNHG16 according to three distinct sets of evidence, i.e., in vitro, animal, and clinical evidence.

Introduction

Small nucleolar RNA host gene 6 (SNHG16) is a member of SNHG family of non-coding RNAs. Long non-coding RNAs (lncRNAs) are a class of transcripts that have sizes longer than 200 nt. These transcripts serve as scaffolds for establishment of different complexes of biomolecules. Moreover, the can serve as enhancers, modulators of chromatin structure and decoys for several molecules, particularly miRNAs {Zhang, 2019 #481}. Bioinformatics tools have facilitated identification of several classes of lncRNAs among them is SNHG group of lncRNAs {Li, 2020 #482}.

Being annotated as NC_000017.11, SNHG16 gene is located on 17q25.1 and has 4 exons. Based on the Ensembl database1, 13 splice variants have been identified for this SNHG16 with one of them having a retained intron (ENST00000587743.1) and the rest being categorized as long non-coding RNAs (lncRNAs). These transcripts have sizes ranging from 556 nt (SNHG16-208) to 3607 nt (SNHG16-201). No protein has been recognized for any of these variants. It has been shown to be ubiquitously expressed in ovary, skin and several other tissues. This lncRNA has fundamental roles in the carcinogenesis in numerous types of tissues. Here, we summarize the results of these studies based on three distinct categories of evidence, i.e., in vitro, animal and clinical evidence.

Cell Line Studies

Small nucleolar RNA host gene 6 has been demonstrated to be up-regulated in lung cancer cell lines, where it acts as a sponge for miR-520a-3p. Through decreasing the availability of this miRNA, SNHG16 increases expression of EphA2. SNHG16 silencing has suppressed proliferation, migratory potential and invasiveness of these cells, while stimulating cell apoptosis. Further experiments have shown the prominence of SNHG16/miR-520a-3p/EphA2 axis in the regulation of oncogenicity in lung cancer (). Being transcriptionally regulated by YY1, SNHG16 also sequesters miR-4500 to modulate expression of the deubiquitinase USP21. USP21 can further increase expression of SNHG16 (). Another experiment in lung cancer cells has identified miR-146a as the target of SNHG16, through its sequestering SNHG16 enhances proliferation, migration and invasiveness of lung cancer cells. The sponging effect of SNHG16 on this miRNA leads to over-expression of MUC5AC, a protein which accelerates metastasis and recurrence of lung cancer cells (). Figure 1 depicts the roles of SNHG16 in lung cancer which are exerted via sponging miR-520a-3p, miR-4500 and miR-146a.

FIGURE 1

Small nucleolar RNA host gene 6 has also important impacts on the modulation of tumor microenvironment through influencing function of γδ immunosuppressive T cells. Mechanistically, SNHG16 works as a sponge for miR-16-5p, thus augmenting expression of SMAD5 and potentiating the TGF-β1/SMAD5 pathway to increase expression of CD73 in Vδ1 T cells (). In addition, SNHG16 can enhance migratory potential of breast cancer cells via sequestering miR-98 and releasing E2F5 from its inhibitory effects (). In prostate cancer cells, siRNA-mediated silencing of SNHG16 results in down-regulation of GLUT-1, reduction of glucose uptake and inhibition of proliferation of cancerous cells without affecting normal prostate cells (). Figure 2 shows the oncogenic roles of SNHG6 in breast and prostate cancers.

FIGURE 2

In hepatocellular carcinoma (HCC), SNHG16 has diverse oncogenic as well as tumor suppressor roles (Figures 3, 4). SNHG16 has been shown to accelerate proliferation, migratory aptitude and invasiveness of HCC cells through sequestering miR-186 and enhancing expression of ROCK1 (). Moreover, miR-4500 is another sponged miRNA by SNHG16 through which this lncRNA promotes development of HCC (). In this type of cancer, SNHG16 also interacts with miR-302a-3p to increase expression of FGF19 and enhance cell proliferation (). Metastatic ability of HCC cells can be regulated by SNHG16 through sequestering miR-605-3p. This miRNA can suppress epithelial-mesenchymal transition (EMT) and metastatic ability of HCC via directly suppressing TRAF6 expression and further modulating NF-κB signaling. Being up-regulated by SNHG16, TRAF6 can in turn increase activity of SNHG16 promoter through activation of NF-κB, thus constructing an positive feedback loop in favor of HCC progression ().

FIGURE 3

FIGURE 4

Contrary to the mentioned studies which reported the oncogenic effects of SNHG16 in the development of HCC, a single study has revealed down-regulation of SNHG16 in HCC cell lines. Ectopic virus-mediated over-expression of SNHG16 has repressed proliferation of HCC cells and attenuated their resistance to 5-FU through sponging hsa-miR-93 ().

In osteosarcoma, sponging impact of SNHG16 on miR-98-5p has an essential impact on proliferation, migration and invasive aptitude of cancer cell. Simultaneously, it can enhance cell cycle progression and decease cell apoptosis (). Meanwhile, through sponging miR-16 and up-regulating ATG4B levels, SNHG16 can induce resistance to cisplatin in these cells (). SNHG16 can also promote proliferation of osteosarcoma cells through sponging miR-205 and enhancing expression of ZEB1 (). Finally, SNHG16 can facilitate EMT of osteosarcoma cells through miR-488/ITGA6 axis (). Figure 5 depicts the oncogenic roles of SNHG16 in osteosarcoma.

FIGURE 5

Small nucleolar RNA host gene 6/miR-124-3p/MCP-1 has an important role in induction of cell proliferation and EMT in colorectal cancer (). The sponging effect of SNHG16 on miR-200a-3p (), miR-132-3p (), and miR-302a-3p (), also promotes tumorigenicity of colorectal cancer.

In cervical cancer cells, SNHG16 has been found to recruit transcriptional factor SPI1 to increase expression of PARP9, thus promoting malignant behaviors of cells (). Moreover, through sponging miR-216-5p, SNHG16 can increase expression of ZEB1, therefore increasing both cell proliferation and EMT process (). Finally, through sponging miR-128, it affects activity Wnt/β-catenin pathway (). Figure 6 summarizes the role of SNHG16 in colorectal and cervical cancers.

FIGURE 6

In neuroblastoma cells, SNHG16 has been revealed to sequester miR-542-3p (), miR-128-3p () and miR-338-3p (), thus increasing expressions of HNF4α, HOXA7, and PLK4, respectively (Figure 7).

FIGURE 7

In other types of cancers, including retinoblastoma, oral squamous cell carcinoma, nasopharyngeal carcinoma, SNHG16 sequesters a number of miRNAs, namely miR-140-5p, miR-182-5p, miR-128-3p, miR-183-5p, miR-17-5p, and miR-520a-3p (Figure 8).

FIGURE 8

In pancreatic cancer, SNHG16 acts in favor of tumor progression through sponging miR-302b-3p and subsequently increasing expression of SLC2A4 (). Moreover, it can contribute in this process through sponging miR-218-5p (). Finally, SNHG16-mediated enhancement of lipogenesis through affecting expression of SREBP2 facilitates progression of pancreatic cancer ().

Small nucleolar RNA host gene 6 participates in the progression of gastric cancer via sequestering miR-628-3p and consequently decreasing expression of NRP1 (). In this type of cancer, SNHG16 also sponges miR-135a and activates JAK2/STAT3 signaling (; Figure 9).

FIGURE 9

Table 1 summarizes the results of in vitro studies regarding the role of SNHG16 in carcinogenesis.

TABLE 1

Tumor typeInteractionsCell lineFunctionReferences
Non−small cell lung cancer (NSCLC)miR-520a-3p, EphA216HBE, A549, NCI-H292, NCI-H460, NCI-H1703Δ SNHG16: ↓ proliferation, ↓ migration, ↓ invasion, ↑ apoptosis
miR-4500, USP21, YY1A549, H1299, NCI-H460, and NCI-H520Δ USP21: ↓ proliferation, ↓ migration, ↓ invasion
miR-146a, MUC5ACA549, NCI-H292, NCI-H460, NCI-H1703, 16HBEΔ SNHG16: ↓ proliferation, ↓ migration, ↓ invasion ↑ SNHG16: ↑ proliferation, ↑ migration, ↑ invasion
Breast cancermiR-16–5p, SMAD5, TGF-β1/SMAD5 pathway, CD73MCF-10A, MCF-7, T-47D, MDA-MB-231, HEK293T_
miR-98, E2F5MDA-MB-231, MCF-7, MDA-MB468 and HEK293TΔ SNHG16: ↓ migration, did not affect proliferation ↑ SNHG16: ↑ migration, did not affect proliferation
let-7a-5p, RRM2MCF-7Δ SNHG16: ↓ proliferation
Prostate carcinomaGLUT122Rv1, HPrECΔ SNHG16: ↓ proliferation, ↓ glucose uptake
Hepatocellular carcinoma (HCC)hsa-miR-93Hep3B, HuH7, SNU398, SNU423, SNU429, Hep3G2, SK-HEP-1, and PLC/PRF/5↑ SNHG16: ↓ proliferation, ↓ 5-FU chemoresistance
miR-17-5p, p62, mTOR pathway, NF-κB pathwayHuh-7 and HepG2Δ SNHG16: ↓ proliferation, ↓ migration, ↓ invasion ↑ SNHG16: ↑ proliferation, ↑ migration, ↑ invasion, ↑ cell cycle progression, ↓ apoptosis
Hepatocellular carcinoma (HCC)miR-186Hep-3B, Huh7, Sk-hep-1, SMMC-7721, PLC, HL-77O2Δ SNHG16: ↓ proliferation, ↓ migration, ↓ invasion
miR-4500, STAT3SMMC-7721, L02, MHCC-97H, HepG2Δ SNHG16: ↓ proliferation, ↓ migration, ↓ invasion, ↑ apoptosis
miR-302a-3p, FGF19Huh7, HepG2, SMMC7721, SK-Hep1 and Hep 3B, LO2Δ SNHG16: ↓ proliferation
miR-605-3p, NF-κB pathwayHCCLM3, MHCC97L, MHCC-97H, L02, Hep3B and HepG2Δ SNHG16: ↓ metastasis, ↓ EMT process
miR-140-5pHepG2, SK-hep1, Huh7, and HCCLM3, LO2, HepG2/SORΔ SNHG16: ↓ sorafenib resistance
miR-195HepG2, SMMC7721, Hep3B, Bel7402, Huh7, LO2Δ SNHG16: ↓ proliferation, ↓ invasion
_HL-7702, SK-Hep-1, Huh7, Hep3B, HepG2Δ SNHG16: ↓ proliferation, ↓ migration, ↓ invasion, ↓ sorafenib resistance
let-7b-5p, CDC25B, HMGA2MHCC97H, HuH7, SMMC7721, Hep3B, HepG2, LO2, HEK293Δ SNHG16: ↑ G2/M cell cycle arrest, ↓ cisplatin resistance, ↓ metastasis, ↓ EMT process
OsteosarcomamiR-98-5pU2OS, Saos-2, HOS, MG-63, hFOB 1.19Δ SNHG16: ↓ proliferation, ↓ migration, ↓ invasion, ↑ cell cycle arrest, ↑ apoptosis
miR-16, ATG4BSAOS2, U2OS, OB3, 293TΔ SNHG16: ↓ proliferation, ↓ migration, ↓ invasion, ↓ autophagy, ↓ chemoresistance
miR-340hFOB1.19, U2OS, SaOS2Δ SNHG16: ↓ viability, ↓ invasion, ↑ apoptosis, ↑ caspase 3/7 activity
miR-1301, BCL9U2OS, MG-63Δ SNHG16: ↓ proliferation, ↓ migration, ↓ invasion
miR-205, ZEB1MG-63, U2OS, SAOS2, HOS, OB3Δ SNHG16: ↓ proliferation
miR-488, ITGA6U2OS, HOSΔ SNHG16: ↓ migration, ↓ invasion, ↓ EMT process
miR-1285-3p, cleaved-caspase-3, Bax, pro-caspase-3, Bcl-2U2OS, MNNG/HOS, 143b, SJSA, MG63, 293, hFOB 1.19Δ SNHG16: ↓ proliferation, ↓ migration, ↓ invasion, ↑ cell cycle arrest, ↑ apoptosis
miR-146a-5p, NOVA1hFOB1.19, MG63, U2OS, 143B, MNNG/HOS↑ SNHG16: ↑ proliferation, ↑ migration
Colorectal cancer (CRC)miR-124-3p, MCP-1HEK293T, FHC, SW480, HCT116, DLD-1, LOVOΔ SNHG16: ↓ proliferation, ↓ migration, ↓ invasion, ↓ EMT process
miR-200a-3pCaCO-2, SW480, HCT116, LoVo, CCC-HIE-2Δ SNHG16: ↓ proliferation, ↓ migration, ↓ invasion
Wnt pathway, c-Myc, AGO, HuR, genes involved in lipid metabolismHCT116, SW480, DLD1, 293T, K562, GM12878Δ SNHG16: ↓ migration, ↑ apoptosis
miR-132-3p, USP22SW480, SW620, CD841 CONΔ SNHG16: ↓ proliferation, ↓ migration, ↓ invasion, ↑ apoptosis
miR-302a-3p, AKTHCT116, CaCO-2Δ SNHG16: ↓ proliferation, ↑ SNHG16: ↑ proliferation
Cervical cancerPARP9, SPI1SiHa, CaSki, C33A, ME180, HeLa, HcerEpicΔ SNHG16: ↓ proliferation, ↓ invasion
miR-216-5p, ZEB1HeLa, CaSki, SiHa, C33A, H8Δ SNHG16: ↓ proliferation, ↓ migration
miR-128, GSPT1, WNT3A, WNT pathwayEndl/E6E7, HeLa, C33AΔ SNHG16: ↓ proliferation, ↓ EMT process
Neuroblastoma (NB)_SH-SY5YΔ SNHG16: ↓ proliferation, ↓ migration, ↑ G0/G1 phase arrest, ↑ apoptosis
miR-542-3p, HNF4α, RAS/RAF/MEK/ERK signaling pathwaySKNBE-2, SK-N-SH, HEK293, LAN-5Δ SNHG16: ↓ proliferation, ↓ migration, ↓ invasion, ↓ EMT process
miR-128-3p, HOXA7SK-N-SH, IMR-32, SK-N-AS, SK-NDZ, HUVECΔ SNHG16: ↓ proliferation, ↓ migration, ↓ invasion, ↑ apoptosis
miR-542-3p, ATG5LAN1, SK-N-SH and IMR-32, HUVECΔ SNHG16: ↓ proliferation, ↓ migration, ↓ invasion, ↓ autophagy
miR-338-3p, PLK4, PI3K/AKT pathwaySK-N-AS, SK-N-SH, SK-N-AS-R and SK-N-SH-RΔ SNHG16: ↓ cisplatin resistance, ↓ malignant phenotypes
Retinoblastoma (RB)miR-140-5pARPE-19, WERI Rb1, SO-RB-50, Y79, SO-Rb50Δ SNHG16: ↓ proliferation, ↓ colony formation, ↑ apoptosis
miR-182-5p, miR-128-3p, LASP1WERI-RB1, SO-RB50, Y79, ARPE-19Δ SNHG16: ↓ migration, ↓ invasion
miR-183-5p, NRASARPE-19 and human RB cell lines Y-79, WERI-Rb-1, 67BR and SO-Rb50Δ SNHG16: ↓ proliferation, ↓ migration, ↓ invasion, ↑ apoptosis
Oral squamous cell carcinoma (OSCC)c-Myc, E-cadherin, N-cadherin, Snail, MMP-2, MMP-9, PCNASCC-25, CAL-27, NHOK, Tca8113, TSCCAΔ SNHG16: ↓ proliferation, ↓ migration, ↓ invasion, ↓ EMT process, ↑ apoptosis
miR-17-5p, CCND1, N-cadherin, VimentinNOK, CAL27, TCA8113, OEC-M1, TW2.6Δ SNHG16: ↓ proliferation, ↑ apoptosis ↑ SNHG16: ↑ proliferation, ↑ migration, ↑ EMT process
Pancreatic cancer (PC)miR-302b-3p, SLC2A4HPY-Y5, BxPC3, Panc-1, MIA Paca-2, SW1990Δ SNHG16: ↓ proliferation, ↓ migration, ↓ invasion, ↑ apoptosis
miR-218-5p, HMGB1BxPC-3, SW1990, PANC-1, AsPC1, HPDE6-C7Δ SNHG16: ↓ proliferation, ↓ colony formation, ↓ migration, ↓ invasion
miR-195, SREBP2HPDE6-C7, PANC-1, AsPC-1, BxPC-3, SW1990, HEK-293Δ SNHG16: ↓ proliferation, ↓ migration, ↓ invasion, ↓ lipogenesis
Nasopharyngeal carcinoma (NPC)miR-520a-3p, MAPK1SUNE1, 5–8F, C666-1, NP69Δ SNHG16: ↓ proliferation, ↓ metastasis
Gastric cancermiR-628, NRP1BGC-823, SGC-7901, MKN-45, AGS, GES-1Δ SNHG16: ↓ proliferation, ↓ migration, ↓ invasion
miR-135a, JAK2/STAT3 pathwayBGC823, MGC803, MKN45, SGC7901, GES-1Δ SNHG16: ↓ proliferation, ↓ colony formation, ↓ invasion
Papillary thyroid cancer (PTC)miR-497, BDNF, YAP1IHH-4, TPC-1, HTH83, Nthy-ori 3-1Δ SNHG16: ↓ proliferation, ↓ migration, ↓ invasion, ↑ apoptosis
Bladder cancer (BC)p21T-24, BIU87, 5637, SV-HUC-1Δ SNHG16: ↓ proliferation, ↓ colony formation, ↑, G1 phase arrest, ↑ apoptosis
miR-17-5p, TIMP35637, J82, RT4, T24Δ SNHG16: ↓ proliferation, ↓ viability, ↓ EMT process, ↑ apoptosis
Ovarian cancerP-AKT, MMP9SKOV-3, ES2, HO8910, OMC685, OSE-29Δ SNHG16: ↓ proliferation, ↓ migration, ↓ invasion
Acute myeloid leukemia (AML)miR183-5p, FOXO1THP1, HL60, Kasumi 3, AML139, PBMCsΔ SNHG16: ↓ proliferation, ↑ G0/G1-phase arrest, ↑ apoptosis
CELF2, PTEN, PI3K/AKT signalingHS-5, HL60, BDCM, AML-193, Kasumi-6Δ SNHG16: ↓ proliferation, ↓ migration ↑ SNHG16: ↑ proliferation, ↑ migration
LeukemiamiR-193a-5p, CDK8Kasumi-1, KG-1, MV-4-11, THP-1, K-562, HL-60, RPMI-1788Δ SNHG16: ↓ proliferation, ↓ viability, ↑ apoptosis
Acute lymphoblastic leukemiamiR-124-3p,MOLT3, MOLT4, SUP-B15, CCRF-CEM, RS4;11, TALL104, CEM/C1, CEM/C2, Loucy, BMMC, PBMC↑ SNHG16: ↑ proliferation, ↑ migration
Large B-cell lymphomamiR-497-5p, PIM1OCI-LY7, OCI-LY3Δ SNHG16: ↓ proliferation, ↑ G0/G1 phase arrest, ↑ apoptosis
Multiple myelomamiR-342-3pRPMI-8226, NCI-H929Δ SNHG16: ↓ proliferation
GliomamiR-373, EGFR, PI3K/AKT pathwayNHAs, U251, LN229, U87Δ SNHG16: ↓ proliferation, ↓ migration, ↓ invasion
GliomamiR-490, PCBP2T98G, U251, NHAΔ SNHG16: ↓ proliferation, ↓ migration, ↓ invasion
miR-4518, PRMT5, Bcl-2, PI3K/Akt pathway,NHAs, U251, H4, SW1783, LN229Δ SNHG16: ↓ proliferation, ↑ apoptosis
miR-212-3p, USF1, ALDH1A1HA, U87, U251, HEK293TΔ SNHG16: ↓ proliferation, ↓ migration, ↓ invasion, ↓ VM
miR-424-5p,T98G, LN229↑ SNHG16: ↓ effect of Ropivacaine, ↑ proliferation, ↑migration, ↑ invasion, ↓ apoptosis
TLR7, NFκB/c-Myc signaling, MyD88SHG44, U251Δ SNHG16: ↓ proliferation, ↓ migration, ↓ invasion ↑ SNHG16: ↑ proliferation,↑ migration, ↑ invasion
Endometrial carcinomamiR-490-3p, TFAP2A, HK2HEC-1B, HEC-1A, RL95-2, AN3CA, EMCΔ SNHG16: ↓ proliferation, ↓ glycolysis
Laryngeal squamous cell carcinomamiR-877-5p, FOXP416HBE, AMC-HN-8Δ SNHG16: ↓ proliferation, ↓ migration, ↓ invasion
Esophageal cancerWnt/β-catenin pathwayTE-13, TE-1, EC-1, Eca-109, HEECΔ SNHG16: ↓ proliferation, ↓ invasion, ↑ apoptosis
miR-140-5p, ZEB1eca109, EC9706, TE1, Kyse-30, Kyse-70, HEECΔ SNHG16: ↓ proliferation, ↓ migration, ↓ EMT process, ↑ apoptosis
Hemangioma (HA)miR-520d-3p, STAT3HemECsΔSNHG16: ↓ proliferation, ↓ migration, ↓ invasion, ↓ vasoformation, ↑ apoptosis

Outline of researches which measured expression of SNHG16 in cell lines (Δ, knock-down or deletion; 5-FU, 5-fluorouracil; VM, vasculogenic mimicry).

Animal Studies

Animal studies have consistently shown that SNHG16 silencing decreases malignant feature of the grafted cancer cells (Table 2). The only exception has been reported in HCC where SNHG16 over-expression has significantly suppressed the in vivo expansion of grafted HuH7 cells (). Another study in HCC xenograft model has shown that SNHG16 silencing enhances response of HepG2/SOR cells to cytotoxic effect of sorafenib and attenuates tumor growth (). In xenograft models of retinoblastoma, up-regulation SNHG16 () or its downstream target NRAS () can increase tumor growth. Finally, in gastric cancer where SNHG16 sponges miR-628, in vivo studies have shown that up-regulation of miR-628 can decrease tumor expansion ().

TABLE 2

Tumor TypeAnimal modelsResultsReferences
Non−small cell lung cancer (NSCLC)male Athymic BALB/c miceΔ SNHG16: ↓ tumor volume, ↓ tumor weight, ↓ tumor growth
male Athymic BALB/c miceΔ SNHG16: ↓ tumor volume, ↓ tumor weight
Hepatocellular carcinoma (HCC)athymic nude mice↑ SNHG16: ↓ tumorigenicity
male athymic nude miceΔ SNHG16: ↓ tumor size, ↓ tumor weight ↑ SNHG16: ↑ tumor size, ↑ tumor weight
female BALB/c nude miceΔ SNHG16: ↓ tumor volume, ↓ tumor weight, ↓ tumor growth ↑ SNHG16:↑ tumor volume, ↓ tumor growth
nude miceΔ SNHG16: ↓ number and size of metastatic colonies, ↓ tumor weight, ↓ tumor growth
Male Athymic nu/nu nude miceΔ SNHG16: ↓ tumor size, ↓ tumor weight, ↓ tumor growth, ↓ sorafenib resistance
male BALB/c nude miceΔ SNHG16: ↓ tumor weight, ↓ tumor growth
BALB/c nude miceΔ SNHG16: ↓ tumor volume, ↓ tumor weight, ↓ metastatic
Osteosarcomamale BALB/c miceΔ SNHG16: ↓ tumor volume, ↓ EMT process, ↓ tumor growth, ↓ metastasis
male BALB/c nude miceΔ SNHG16: ↓ tumor volume, ↓ tumor weight
Colorectal cancer (CRC)nude miceΔ SNHG16: ↓ tumor size, ↓ tumor weight, ↓ metastasis
male BALB/c nude mice↑ SNHG16: ↑ tumor size
male BALB/c-nude miceΔ SNHG16: ↓ tumor weight, ↓ metastasis, ↓ tumor growth
Cervical cancerspecific-pathogen-free BALB/c-nu/nu nude miceΔ SNHG16: ↓ tumor growth
Neuroblastoma (NB)BALB/c nude miceΔ SNHG16: ↓ tumor volume, ↓ tumor weight; ,
athymic BALB/c miceΔ SNHG16: ↓ tumor volume, ↓ tumor weight
Retinoblastoma (RB)male BALB/c nude miceΔ SNHG16: ↓ tumor volume, ↓ tumor weight
female BALB/c nude miceΔ NRAS: ↓ tumor volume, ↓ tumor weight
Oral squamous cell carcinomaBALB/c-nude miceΔ SNHG16: ↓ tumor volume, ↓ tumor weight
male athymic BALB/c nude miceΔ SNHG16: ↓ tumor growth ↑SNHG16: ↑ tumor growth
Pancreatic cancermale BALB/c nude miceΔ SNHG16: ↓ tumor volume, ↓ tumor growth
Nasopharyngeal carcinoma (NPC)male BALB/C nude miceΔ SNHG16: ↓ tumor volume, ↓ tumor weight
Gastric cancerfemale BALB/c nude mice↑ miR-628: ↓ tumor volume, ↓ tumor weight
Acute lymphoblastic leukemia (ALL)null miceΔ SNHG16: ↓ tumor volume, ↓ ALL tumor transplants
Large B−cell lymphoma (DLBCL)male NOD/SCID miceΔ SNHG16: ↓ tumor growth
Gliomaathymic BALB/c nude miceΔ SNHG16: ↓ tumor volume, ↓ number of VMs, ↑ survival period
Endometrial carcinomamale nude BALB/c miceΔ SNHG16: ↓ tumor volume, ↓ tumor growth
Laryngeal squamous cell carcinoma (LSCC)female nude miceΔ SNHG16: ↓ tumor volume, ↓ tumor weight
Esophageal cancerfemale BALB/c athymic nude miceΔ SNHG16: ↓ tumor growth

Outline of studies which judged function of SNHG16 in animal models (Δ, knock-down or deletion; VM, vasculogenic mimicry).

Clinical Studies

Except for a single study which demonstrated down-regulation of SNHG16 in HCC samples versus nearby non-malignant hepatic tissues (), other studies have indicated up-regulation of SNHG16 in malignant tissues of different origins compared with non-neoplastic samples (Supplementary Table 1). Consistent with these findings, up-regulation of SNHG16 has been revealed to predict poor survival of patients. Moreover, its expression has been related with greater chance of distant metastasis, lymph node involvement and low differentiation of tumor cells.

Discussion

Small nucleolar RNA host gene 6 has been regarded as an oncogenic lncRNA in almost all tissues. This lncRNA affect carcinogenesis through multifaceted mechanisms including mechanisms related to both tumor cells and their niche. In fact, it can both affect cellular functions and processes, particularly those related with proliferation, survival and apoptosis as well as microenvironmental aspects of cancer progression.

More than 20 miRNAs have been found to interact with SNHG16. The sponging effects of SNHG16 on miRNAs have been well studied. miR-520a-3p, miR-4500, miR-146a miR-16–5p, miR-98, let-7a-5p, hsa-miR-93, miR-17-5p, miR-186, miR-302a-3p, miR-605-3p, miR-140-5p, miR-195, let-7b-5p, miR-16, miR-340, miR-1301, miR-205, miR-488, miR-1285-3p, miR-146a-5p, and miR-124-3p are examples of miRNAs sponged by this lncRNA in different types of cancers. Verification of interaction between this lncRNA and a number of miRNAs such as miR-98 in different tissues raises the possibility of independence of such interactions from the tissue type. TGF-β1/SMAD5, mTOR, NF-κB, RAS/RAF/MEK/ERK, PI3K/AKT, and Wnt/β-catenin pathways are among cancer-related pathways being affected by this lncRNA. Moreover, SNHG16 has been shown to affect expression of a number of EMT-associated transcription factors and enhance this process. SNHG16 has also been found to affect response of cancer cells to 5-FU and sorafenib.

Based on the results of functional studies that confirmed the ability of siRNA-mediated SNHG16 silencing in reduction of cancer cell proliferation and invasiveness, this strategy can be proposed as a therapeutic strategy for cancer. In vivo studies have also confirmed applicability of these methods; however no clinical study has applied these methods yet. Antisense oligonucleotides as a promising strategy for suppression of expression of SNHG16 should be appraised in clinical settings considering the bioavailability and safety issues.

Although over-expression of SNHG16 has been verified in tissue samples of different types of tumors, application of this lncRNA as a circulatory marker for early detection of cancer has not been assessed. Since clinical studies have revealed correlation between expression amounts of SNHG16 and malignant features, one can suppose that SNHG16 can be used as both diagnostic and prognostic marker. However, this speculation should be verified in future.

Publisher’s Note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

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Author contributions

MT and SG-F wrote the draft and revised it. TK and SS collected the data and designed the tables and figures. All authors read and approved submitted version.

Conflict of interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Supplementary material

The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fcell.2021.741684/full#supplementary-material

References

Summary

Keywords

SNHG6, lncRNA, cancer, biomarker, expression

Citation

Ghafouri-Fard S, Khoshbakht T, Taheri M and Shojaei S (2021) A Review on the Role of Small Nucleolar RNA Host Gene 6 Long Non-coding RNAs in the Carcinogenic Processes. Front. Cell Dev. Biol. 9:741684. doi: 10.3389/fcell.2021.741684

Received

15 July 2021

Accepted

09 September 2021

Published

04 October 2021

Volume

9 - 2021

Edited by

Shiv K. Gupta, Mayo Clinic, United States

Reviewed by

Rezvan Noroozi, Jagiellonian University, Poland; Amin Safa, Complutense University of Madrid, Spain

Updates

Copyright

*Correspondence: Mohammad Taheri, Seyedpouzhia Shojaei,

This article was submitted to Molecular and Cellular Oncology, a section of the journal Frontiers in Cell and Developmental Biology

Disclaimer

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.

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