ZFAS1: A novel vital oncogenic lncRNA in multiple human cancers

Abstract

Long noncoding RNAs (lncRNAs) are a class of noncoding, endogenous, single‐stranded RNAs longer than 200 nucleotides in length that are transcribed by RNA polymerase II. Mounting evidence has indicated that lncRNAs play key roles in several physiological and pathological processes by modifying gene expression at the transcriptional, posttranscriptional, epigenetic, and translation levels. Many reports have demonstrated that lncRNAs function as potential oncogene or tumour suppressors and thus play vital regulatory roles in tumourigenesis and tumour progression. ZNFX1 antisense RNA 1 (ZFAS1), a novel lncRNA transcribed in the antisense orientation of zinc finger NFX1‐type containing 1(ZNFX1), was found to be increased in multiple cancers, such as gastric cancer and hepatocellular carcinoma, contributing to cancer development and progression. In the present review, we summarized recent progression on study of the functions and underlying molecular mechanisms of ZFAS1 related to occurrence and development of multiple cancers.

Full text

Cell Proliferation. 2019;52 :e12 513 . wileyonlinelibrar y.com/journal/cpr
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https://doi.org/10.1111/cpr.12513
1 | INTRODUCTION
Recently, due to increasing incidence and mortality, cancer is one
of the leading public health problems all over the world and con-
tinues to capture our great attention.1 In the light of estimates in
a comprehensive overview called Cancer Statistics, 2017, there
were 1 688 780 new patients predicted to be diagnosed with can-
cers and 600 920 patients were predicted to die of cancers in the
United States are predicted to occur in 2017.2 In China, there were
an estimated 4 292 000 new cancer patients and 2 814 000 pa-
tients who died of cancers have occurred in 2015.3 Despite mul-
tiple treatments modalities being accessible for cancer patients,
including surgery, chemotherapy, radiation therapy, and targeted
therapy, the 3- and 5- year cancer- specific survival rates still remain
po or.1,4 Exploration of and revealing the molecular mechanisms im-
portant to cancer is therefore critical in order to identify new diag-
nostic and prognostic biomarkers as well as effective treatments.
Less than 2% of genes are associated with the production of
specific proteins according to eukaryote whole- genome sequenc-
ing.5 Furthermore, more than 70% of identified genes had no
protein- coding function.5 At first, such noncoding RNAs (ncRNAs)
were considered to be transcriptional noise with no specific biologi-
cal function.6 With further research of ncRNAs, however, they have
been identified as indispensable regulators of a variety of biological
processes, including epigenetics, cell cycle, posttranscriptional reg-
ulation and chromatin modification.6-8 Although we currently lack
satisfactory classifications for these ncRNAs, long ncRNAs are ar-
bitrarily considered to be longer than 200 nucleotides.6 ,9 Mounting
evidence has indicated that lncRNA plays key roles in physiolog-
ical and pathological processes by modifying gene expression at
the transcriptional, posttranscriptional, epigenetic, and translation
levels.6-8 Several reports have demonstrated that lncRNAs could
function as potential oncogenes or tumour suppressor genes in
order to play vital regulatory roles in tumourigenesis and tumour
progression.10,11
Received:6February2018
|
Accepted:13June2018
DOI : 10.1111 /cpr.12 513
REVIEW
ZFAS1: A novel vital oncogenic lncRNA in multiple human
cancers
Anbang He | Shiming He | Xuesong Li | Liqun Zhou
Anban g He and Shi ming He are the aut hors who contr ibuted equall y.
Depar tment of Urology, The Institute
of Urolog y, Peking Universit y First
Hospital, Peking University, National
Urologi cal Cancer Centre, Beijing 100034,
China
Correspondence: Liqun Zhou and Xueson g
Li, Department of Urolog y, The Institute of
Urolog y, Peking Uni versit y First H ospita l,
Peking University, National Urological
Cancer Centre, B eijing 100034, China
(zhoulqmail@sina.com; pineneedle@sina.
com).
Funding information
Nationa l Natural Science Fo undation of
China; Natural Science Foun dation of
Beijing, Grant/Award Number: 71772219
and 7152146; The Shenzhen Municipal
Government of China, Grant/Award
Number: ZDSYS201504301722174,
JCYJ2015033 0102720130and
GJHZ2015031615491 2494
Abstract
Long noncoding RNAs (lncRNAs) are a class of noncoding, endogenous, single-
stranded RNAs longer than 200 nucleotides in length that are transcribed by RNA
polymerase II. Mounting evidence has indicated that lncRNAs play key roles in sev-
eral physiological and pathological processes by modifying gene expression at the
transcriptional, posttranscriptional, epigenetic, and translation levels. Many reports
have demonstrated that lncRNAs function as potential oncogene or tumour suppres-
sors and thus play vital regulatory roles in tumourigenesis and tumour progression.
ZNFX1 antisense RNA 1 (ZFAS1), a novel lncRNA transcribed in the antisense orien-
tation of zinc finger NFX1- type containing 1(ZNFX1), was found to be increased in
multiple cancers, such as gastric cancer and hepatocellular carcinoma, contributing
to cancer development and progression. In the present review, we summarized re-
cent progression on study of the functions and underlying molecular mechanisms of
ZFAS1 related to occurrence and development of multiple cancers.
This is an op en access article under the terms of the Creati ve Commons Attribution Li cense, wh ich perm its use, distribution an d reproduction in any mediu m,
provide d the original work is properly cited.
© 2018 The Aut hors Cell ProliferationPublishedbyJohnW iley&SonsLtd

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ZNFX1 antisense RNA 1 (ZFAS1), a novel lncRNA transcribed
from the antisense orientation of zinc finger NFX1- type cont ain-
ing 1(ZNFX1), is located on chromosome 20q13.13 (Figure 1).12
Recent research has reported that ZFAS1 may act an emerging
regulatory factor in multiple diseases, such as acute myocardial
infarction,13,14 rheumatoid arthritis,15 and cancer.16 Accumulating
evidence has suggested that the abnormal expression of ZFAS1
contributes to the occurrence and development of various can-
cers, including gastric cancer, hepatocellular carcinoma, colorectal
cancer, glioma, osteosarcoma, ovarian cancer, acute myeloid leu-
kaemia, nonsmall cell lung cancer (NSCLC), oesophageal squamous
cell carcinoma, and breast cancer. In this review, we summarized
recent progression regarding study of the functions and underly-
ing mechanisms of ZFAS1 in the occurrence and development of
various cancers.
2 | DISCOVERY OF ZFAS1
ZFAS1, firstly studied in breast cancer by Marjan, is transcribed
from the gene ZNFX1 on the antisense DNA strand near the 5′
end. It is located in both cellular cytoplasmic and nuclear fractions
with a leng th of 17 561 bp, including five exons with five transcrip-
tional variations (NR _003604.3:1008 bp; NR_003605.2:689 bp;
NR_0 03606.3 :860 b p; NR_036658 .2: 946 b p; NR_036659.2:504 bp).
ZFAS1 hosts three small nucleolar RNAs (snoRNAs), including
Snord12, Snord12b, and Snord12c.12 SnoRNAs, a class of RNA mol-
ecules with 60- 150 nt in length which may be involved in the chemi-
cal modifications of other RNAs, like transfer RNAs, ribosomal RNAs,
and small nuclear RNAs.17 Current research has indicated that upreg-
ulation of ZFAS1 is positively correlated with clinicopathologic al fea-
tures and prognosis, including TNM stage, lymph-node metastasis,
FIGURE1 ZFAS1 was located on chromosome 20q13.13 and transcribed in antisense orientation of ZNFX1 and also hosts three small
nucleolar RNAs, including Snord12, Snord12b, and Snord12c
TABLE1 Functional characterizations of ZFAS1 in multiple human cancers
Cancer t ypes Expression Role Functional role Related genes References
Colorectal cancer Upregulated Oncogenic Cell proliferation migration, invasive,
metastasis, cell cycle control, cell
antiapoptosis
miR- 484
miR- 590- 3p
p53 and EMT
signalling
pathway
21-24
Gastric cancer Upregulated Oncogenic Cell proliferation, cell antiapoptosis, cell
migration and metastasis, cell cycle control
EMT, KLF2, EZH2,
NKD2
25-27
Hepatocellular
carcinoma
Upregulated Oncogenic Cell invasion and tumour metastasis miR- 150, ZEB1,
MMP14, and
MMP16
28
Glioma Upregulated Oncogenic Cell proliferation, migration, and invasive Notch and EMT
signalling
pathway
30,31
Osteosarcoma Upregulated Oncogenic Cell proliferation, migration and invasion, cell
antiapoptosis, cell cycle control
miR- 200b/c,
miR- 486, BMI1,
ZEB2
32,33
Ovarian cancer Upregulated Oncogenic Cell proliferation migration, chemoresistance miR- 150 - 5p, Sp1 34,35
Acute myeloid
leukaemia
Upregulated Oncogenic Cell proliferation, cell antiapoptosis, cell cycle
control
36
Nonsmall cell lung
cancer
Upregulated Oncogenic 37
Oesophageal squamous
cell carcinoma
Upregulated Oncogenic 29

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and overall survival. Several meta- analyses have indicated that
lncRNA ZFAS1 could be as a prognostic biomarker for patients with
various cancers.16,18-20 Upregulated ZFAS1 could function as an on-
cogene to promoting cell proliferation, migration, and invasion. The
relevant clinicopathological features and underlying molecular mech-
anisms of ZFAS1 in various cancers are summarized in Tables 1 and 2.
3 | ZFAS1 IN VARIOUS HUMAN CANCERS
Accumulating evidence has demonstrated the abnormal expression of
ZFAS1 in multiple cancers, including gastric cancer, hepatocellular car-
cinoma, colorectal cancer, glioma, osteosarcoma, ovarian cancer, acute
myeloid leukaemia, NSCLC, oesophageal squamous cell carcinoma, and
breast cancer. Specifically, the expression of ZFAS1 was found to be
upregulated in most cancers, except breast cancer. Upregulation of
ZFAS1 expression was positively associated with advanced TNM stage
and lymph-node metastasis in colorectal cancer, gastric cancer, ovar-
ian cancer, and NSCLC. Additionally, increased expression of ZFAS1
was closely correlated with poorer overall survival in colorec tal cancer,
gastric cancer, glioma, osteosarcoma, oesophageal squamous cell car-
cinoma, ovarian cancer, and NSCLC. The association between ZFAS1
expression and the relevant clinicopathological features of various can-
cers are summarized in Table 1. Overexpression of ZFAS1 was shown
to promote cell proliferation and induced cellular apoptosis in various
cancers, including colorectal cancer, gastric cancer, glioma, osteosar-
coma, acute myeloid leukaemia, and ovarian cancer. Interestingly,
knockdown of ZFAS1 inhibited cell migration and invasion in colorectal
cancer, gastric cancer, glioma, hepatocellular carcinoma, osteosarcoma.
The functions and underlying molecular mechanisms of ZFAS1 in vari-
ous cancers are summarized in Table 2 and detailed in the rest of this
review.
3.1 | Colorectal cancer
ZFAS1 has been found in several studies to be overexpressed in
colorectal cancer tissues and cell lines compared with paired adja-
cent normal colorectal tissues and a human colonic epithelial cell
line, HCoEpiC. Fang et al21 demonstrated that upregulated ZFAS1
expression was positively associated with an advanced TNM stage,
vascular invasion, and lymph-node metastasis. Overexpression of
ZFAS1 promoted cell proliferation, invasion, and induced cell ap-
optosis in colorectal cancer (CRC). Furthermore, silencing of ZFAS1
could reduce Zinc Finger E- Box Binding Homeobox 1 (ZEB1) expres-
sion and increased the expression of epithelial markers, including
E- cadherin and ZO- 1, meanwhile decreasing the expression of mes-
enchymal markers, including vimentin and N- cadherin. Taking into
account these results, the researchers concluded that ZFAS1 could
function as an oncogene by promoting ZEB1 induction of epithelial-
to- mesenchymal transition (EMT).
Wang et al22 confirmed that the expression of ZFAS1 was higher
in CRC tissues than in adjacent normal colorectal tissues. Moreover,
compared with primary CRC tumours, ZFAS1 was upregulated in
metast atic tumours, suggesting ZFAS1 may have a specific role in
such cancer metastasis. Furthermore, ZFAS1 expression in CRC
was positively correlated with lymphatic invasion and TNM stage.
Increased ZFAS1 levels were determined to predict poor overall sur-
vival and short relapse- free sur vival and cox multivariate analyses
revealed that ZFAS1 expression is an independent prognostic factor
in CRC. Silencing ZFAS1 expression could suppress cell migration,
invasive, and metast asis ability of CRC cell in vitro and in vivo. Xie
et al23 also confirmed that elevated ZFAS1 expression was signifi-
cantly associated with advanced TNM stage, lymph-nodes met as-
tasis, and poor overall survival. Functional experiment s indicated
that downregulated ZFAS1 inhibited cell proliferation and invasion
Cancer t ypes Clinicopathological features References
Colorectal cancer Positive helicobacter pylori, advanced TNM
stage, positive lymph-node metastasis, poorer
overall survival, higher recurrence rate, positive
lymphatic invasion, and positive microvascular
invasion
21-24
Gastric cancer Advanced TNM stage, higher T s tage, positive
lymph-node metastasis , larger tumour size
25-27
Hepatocellular Carcinoma Positive microvascular invasion, shorter overall
survival, and higher recurrence rate
28
Oesophageal squamous cell
carcinoma
Poorer histological grade, shorter overall
survival
29
Glioma Higher clinical stage, poorer overall survival 30,31
Osteosarcoma Poorer overall survival 32,33
Ovarian cancer Poorer overall survival, advanced tumour stage,
larger tumour size, positive ly mph-node
metastasis
34,35
Nonsmall cell lung cancer Advanced TNM stage, positive lymph-node
metastasis, poor differentiation, poorer overall
survival
37
TABLE2 Clinical features of ZFAS1 in
multiple human cancers

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both in vitro and in vivo. Bioinformatics analysis and experiments
also proved that ZFAS1 directly interacted with miR- 484. Thorenoor
et al24 showed that silencing ZFAS1 decreased cyclin- dependent ki-
nase 1 (CDK1) to inhibit cell proliferation through G1- arrest of cell
cycle by sponging miR- 590- 3p in CRC cells. Decreased ZFAS1 ex-
pression resulted in reduction of p53 and cyclin B1 levels and pro-
moting poly ADP- ribose polymerase (PARP) cleavage to induce cell
apoptosis. These findings demonstrated that ZFAS1 could act an on-
cogenic lncRNA which may serve as a novel independent prognostic
biomarker for patient s with CRC.
3.2 | Gastric cancer
Current research trends have explored the function and molecular
mechanisms of ZFAS1in gastric cancer. Zhou et al, 25 Pan et al,26 and
Nie et al27 all demonstrated the elevated expression of ZFAS1 in
gastric cancer tissues and cell lines, compared to adjacent nontu-
mour tissues and normal gastric cell line (GES- 1). Increased expres-
sion of ZFAS1 in gastric cancer was also closely interrelated with
TNM stage, lymph- node metastasis, and tumour size. Kaplan- Meier
analysis revealed that GC patient s with higher ZFAS1 expression
levels had poorer overall survival (OS) and progression- free survival
(PFS) than those with lower ZFAS1 expression levels. Knockdown
of ZFAS1 suppressed cancer cells proliferation and promoted can-
cer cells apoptosis in vitro, and restrained tumourigenesis of gastric
cancer cells in vivo. Further research showed that ZFAS1 could si-
multaneously interact with the enhancer of zeste homolog 2 (EZH2)
and lysine demethylase 1A/histone demethyltransferase of REST
complex (L SD1/CoREST) to inhibit Kruppel Like Factor 2 (KLF2)
and Naked Cuticle Homolog 2 (NKD2) transcription. Moreover,
rescue experiments suggested that ZFAS1 par tially relied on sup-
pression of KLF2 and NKD2 to exert its oncogenic effect s. Zhou
et al25 found that circulating ZFAS1 was also overexpressed in GC
patients and that surgery operation could decrease subsequent ex-
pression in plasma. Finally, to elucidate the potential diagnostic value
of plasma ZFAS1, receiver operating characteristic (ROC) curve and
the Youden index were calculated. The area under the ROC cur ve
(AUC) was 0.727 (95% CI: 0.6 42- 0.813, P < 0.001), with a sensitivity
of 0.766 and specificity of 0.639. All of these results indicated that
circulating ZFAS1 had a relatively moderate accuracy when distin-
guishing gastric cancer patients from other individuals. Pan et al26
also found that silencing of ZFAS1 repressed cell proliferation and
migration by inhibiting cell cycle and EMT. Finally, ZFAS1 was ob-
served in exosomes and was transported by exosomes to promote
cell proliferation and migration of GC.
3.3 | Hepatocellular carcinoma
Li et al28 reported that ZFAS1 expression was signific antly amplified
in HCC tissues and cell lines compared with the paired nontumour
tissues and normal liver cells. Correlation analysis demonstrated that
high ZFAS1 levels were positively associated with microvascular in-
vasion and recurrence. Kaplan- Meier analysis suggested that HCC
patients with upregulated ZFAS1 experienced poorer overall sur-
vival (OS) and progression- free survival (PFS). Fur ther study showed
that amplified ZFAS1 could enhance HCC cell invasion and tumour
metast asis in vitro and in vivo. Subsequent bioinformatics analysis
and experimentation revealed that ZFAS1 directly interacted with
miR- 150. Moreover, miR- 150 could suppress HCC cell invasion and
metast asis by targeting ZEB1, matrix metallopeptidase 14 (MMP14),
and matrix metallopeptidase 16 (MMP16). From these results, the
authors concluded that ZFAS1 was acting in an oncogenic role by
binding miR- 150 and abrogating its tumour- suppressive function in
HCC progression.
3.4 | Oesophageal squamous cell carcinoma
Shi et al29 demonstrated that ZFAS1 expression was elevated in
oesophageal squamous cell carcinoma (ESCC) and high ZFAS1 was
positively correlated with histological grade. ESCC patient s with
high ZFAS1 expression had poorer OS than those with low ZFAS1
expression both in the primary cohort and validation cohor t. In
both cohorts, both univariate and multivariate analysis confirmed
that ZFAS1 expression, histological grade, and T stage as prognos-
tic factors. A nomogram then used clinicopathological factors and
ZFAS1 expression to predict the prognosis of lymph-node- negative
ESCC patients without preoperative chemoradiotherapy. The result-
ing decision- making curve suggested that the proposed nomogram
wasbetterthan8thAJCC-TNMstaging systemintermsof survival
prediction.
3.5 | Glioma
ZFAS1 expression was markedly overexpressed in glioma tissues and
cell lines in reports by Gao et al30 and Lv et al31 with high ZFAS1
expression in glioma tissues being closely associated with advanced
clinical stage and poor overall survival. Both univariate and multi-
variable Cox regression analysis revealed that upregulated ZFAS1
and the clinical stage were independent prognostic factors in the
overall sur vival of glioma patients. Silencing of ZFAS1 could sup-
press cell proliferation by arresting the cell cycle and inducing cell
apoptosis in glioma. Fur thermore, knockdown ZFAS1 inhibited cell
migration and invasion in glioma. Several EMT markers play indis-
pensable roles in epithelial- mesenchymal transition signalling path-
way, including MMP2, MMP9, E- cadherin, N- cadherin, Integrin β1,
ZEB1, Twist, and Snail. After silencing ZFAS1, the expression levels
of MMP2, MMP9, N- cadherin, Integrin β1, ZEB1, Twist, and Snail
were markedly downregulated, while E- cadherin expression was sig-
nificantly upregulated. Furthermore, the expression of Notch signal-
related proteins Hes family BHLH transcription fac tor 1 (Hes- 1) and
NICD were decreased by silencing ZFAS1. Notch signalling pathway
is believed to function as a vital regulator of embryo development
via the regulation of intercellular signal communication by modifying
cell proliferation and apoptosis. Therefore, these data indicated that
ZFAS1 may enhance glioma progression by activating the EMT and
Notch signalling pathways.

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3.6 | Osteosarcoma
In osteosarcoma tissues and cell lines, Liu et al and Li et al32,33
showed that ZFAS1 was markedly upregulated. Kaplan- Meier analy-
sis suggested that osteosarcoma patients with high ZFAS1 levels had
shorter overall sur vival (OS) than those with low ZFAS1. Functional
experiments revealed that upregulated ZFAS1 promoted osteosar-
coma cell proliferation, migration, and invasion in vitro and in vivo.
Mechanistically, the researchers discovered that ZFAS1 regulated
malignant phenotypes by competitively binding the miR- 200b/c to
increase B Lymphoma Mo- MLV Insertion Region 1 Homolog (BMI1)
expression. Further RNA pull- down assays proved that ZFAS1 inter-
acted with ZEB2 to keep ZEB2 protein stability. Moreover, they found
that specificity protein 1 (SP1) acted as an upstream ac tivated factor
of ZFAS1. Li et al discovered that ZFAS1 sponges miR- 4 86 to promote
osteosarcoma cells progression and metastasis in vitro and vivo.
3.7 | Ovarian cancer
A report by Xia et al34 showed that ZFAS1 was upregulated in
epithelial ovarian cancer (EOC) tissues and cell lines. Amplified
expression ZFAS1 in EOC tissues was positively correlated with
advanced clinical stage, larger tumour size, and lymph- node metas-
tasis. Kaplan- Meier analysis suggested that EOC patients with high
ZFAS1 expression had poorer overall sur vival (OS) than those with
low ZFAS1. Cell experiments revealed that knockdown of ZFAS1
suppressed cell proliferation, migration, and chemoresistance in
EOC. Further research identified downregulated miR- 150- 5p as a
potential t arget of ZFAS1 in EOC tissue. Further luciferase assays
indicated miR- 150- 5p subsequently suppressed transcription fac-
tor SP1 expression. Subsequent rescue experiments revealed than
silencing miR- 150- 5p could partially rescue the suppressed prolif-
eration and migration induced by inhibition of ZFAS1 in EOC cells.
These dat a suggested that ZFAS1/miR- 150- 5p/SP1 axis may play a
critical role in enhancing cell proliferation, migration, and chemore-
sistance in EOC. Additionally, Liu et al35 identified eight lncRNA sig-
natures, which were remarkably correlated with chemosensitivity in
a multivariate logistic regression model and could precisely predict
the chemosensitivity of patients, by analysing the lncRNA expres-
sion profiles of 258 HGS- OvCa patients from The Cancer Genome
Atlas(TCGA). Similarly, data from the Gene Expression Omnibus
dataset s (GEO) confirmed the strong relation between ZFAS1 and
chemosensitivity. In vitro experiments suggested that the ZFAS1
expression was overexpressed with cisplatin treatment in several
EOC cell lines (A2008, HeyA8, and HeyC2). Taken together, these
findings suggested that ZFAS1 may play a vital role in platinum
resistance, which should be further explored.
3.8 | Acute myeloid leukaemia
When compared with normal cell lines, Guo et al30 revealed that the
expression of ZFAS1 was increased in all four human acute myeloid
leukaemia (AML) cell lines. The silencing of ZFAS1 suppressed cell
proliferation in HL-60 and SKNO-1 cell lines according to CCK-8
assay and induced AML cell cycle G1 phase arrest and promoted
cell apoptosis by flow cy tometr y. These findings demonstrated that
upregulated ZFAS1 enhanced cell proliferation and suppressed cell
apoptosis in AML.
3.9 | Nonsmall cell lung cancer
Tian et al36 demonstrated that the expression of ZFAS1 was in-
creased in nonsmall cell lung cancer (NSCLC) compared with adja-
cent noncancerous tissues. A gain, increased ZFAS1 was positively
correlated with advanced TMN stage, lymph-node metastasis, and
poor differentiation. Kaplan- Meier analysis indicated that NSCLC
patients with upregulated ZFAS1 had poorer OS than those with
downregulated ZFAS1. Both univariate and multivariable Cox re-
gression analysis suggested that high ZFAS1 expression TMN stage,
lymph-node metastasis, and differentiation level were independent
prognostic factors for overall survival of NSCLC patients.
3.10 | Breast cancer
Marjan et al12 identified that ZFAS1 as highly expressed in stage
of lactation in mouse mammary gland tissues and was reduced in
human invasive ductal breast carcinoma compared with normal
breast tissues. On the contrary, Hansji et al37 showed that ZFAS1
expression was not significantly different in breast cancer tissues
from normal tissues according to RNAseq data set (HiSeqV2- 2015-
02- 24) from TCGA. However, ZFAS1 expression was significantly
downregulated in basal and HER2 breast cancer subtypes compared
to normal breast tissue. Impor tantly, ER+ breast tumours had higher
expressionofZFAS1thanER−(negative)breasttumours.Thesetwo
studies had different results largely due to their limited number of
samples and testing of different breast cancer subtypes. Next, there
was no significant found between the expression level of ZFAS1 and
ZNFX1. They also found that ZFAS1 was localized to both the cy-
toplasm and the nucleus while ZNFX1 was enriched in the nucleus.
Further research has indicated that ZFAS1 is associated with only
part of the ribosomes, being enriched in 18S rRNA fractions com-
pared to those containing 28S rRNA. The expression of ZFAS1 is
associated with the expression of genes which were involved in ri-
bosome biogenesis. A series of experiments have also demonstrated
that ZFAS1 is induced upon ribosome biogenesis, revealing a role in
the synthesis or assembly of ribosomes.
4 | UNDERLYING MOLECULAR
MECHANISMS OF ZFAS1
4.1 | The molecular level
4.1.1 | Function of ZFAS1 as a ceRNA
Competing endogenous RNAs (ceRNAs), a class of noncoding RNA,
have been shown to modify the mRNA expression of genes by

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acting as miRNA sponges competing for mutual microRNAs, which
simultaneously target both noncoding RNA and genes.38, 39 Several
articles have demonstrated that ZFAS1 could function as a ceRNA
to regulate the expression of specific genes by competing for spe-
cific microRNAs, exerting its oncogenic function in various cancers.
Li et al and Xia et al showed that ZFAS1 directly interacted with
FIGURE2 Underlying molecular mechanisms of ZFAS1 in multiple human cancers. A, ZFAS1 functioned as a ceRNA to directly interac ted
with miR- 150 to increase the expression of ZEB1, MMP14, MMP16, and SP1. B, silencing ZFAS1 could decrease the expression of CDK1
by competing for miR- 590 - 3p. C, ZFAS1 may act as a ceRNA to upregulate the expression of BMI1 by competitively binding miR- 20 0b/c. D,
After Silencing ZFAS1, the expression levels of mesenchymal markers, including MMP2, MMP9, N- cadherin, Integrin β1, ZEB1, Twist, and
Snail, were markedly downregulated, while the expression of epithelial markers including E- cadherin and ZO1 significantly upregulated. E,
ZFAS1 could regulate the expression of Hes- 1 and NICD to activate Notch signalling pathway. F, decreased ZFAS1 contributed to cell-
cycle arrest and inducement of apoptosis by reducing the expression of p53 and cyclin B1 and promoting PARP cleavage. G, ZFAS1 could
simultaneously interact with EZH2 and LSD1/CoREST to inhibit KLF2 and NKD2 transcription. H, SP1 could activate the expression of
ZFAS1

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miR- 150 to increase the expression of ZEB1, MMP14, MMP16, and
transcription factor SP1 (Figure 2A). Thorenoor et al then showed
that silencing of ZFAS1 could decrease the expression of CDK1 in
order to inhibit cell proliferation via G1 arrest of the cell cycle by
competing for miR- 590- 3p in CRC cells (Figure 2B). Liu et al found
that ZFAS1 promoted malignant phenotypes by competitively bind-
ing miR- 200b/c to upregulate the expression of BMI1 (Figure 2C).
The ring finger protein encoded by BMI1 is major component of
PRC1, which acts as an indispensable epigenetic repressor of a va-
riety of regulatory genes involved in self- renewal and embryonic
development by remodelling the chromatin of stem cells. Finally,
Xie et al proved that ZFAS1 could directly interact with miR- 484.
Previous study identified miR- 484 as an inhibitor of cell prolifera-
tion and invasion by targeting ZEB1 and SMAD2 in cervical cancer
cells, revealing that ZFAS1 may promote cell proliferation and inva-
sion via sponging miR- 484 to modulate the expression of ZEB1 and
SMAD2.
4.1.2 | Transcriptional regulation
Further research has demonstrated that ZFAS1 could simultaneously
interact with EZH2 and LSD1/CoREST to inhibit KLF2 and NKD2
transcription. Rescue experiments revealed that ZFAS1 was partly re-
lied on suppressing KLF2 and NKD2 expression to exert its oncogenic
effects (Figure 2G). SP1 was also demonstrated to be an upstream
factor for the activation of ZFAS1 expression (Figure 2H). Moreover,
Hansji et al showed that ZFAS1 was induced upon ribosome biogen-
esis, revealing a role in synthesis or assembly of ribosomes.
4.2 | ZFAS1 is involved in several signalling
pathways
4.2.1 | EMT signalling pathway
EMT plays an essential role in both physiological and pathological
processes, such as embryonic development as well as the occurrence
and development of tumours.40 ,41 Several EMT markers are indis-
pensable in the EMT signalling pathway, including MMP2, MMP9,
E- cadherin, N- cadherin, Integrin β1, ZEB1/2, Twist, and Snail.41
After silencing of ZFAS1, the expression levels of MMP2, MMP9, N-
cadherin, Integrin β1, ZEB1, Twist, and Snail were all markedly down-
regulated, while E- cadherin expression significantly upregulated. In
conclusion, Liu et al also showed that ZFAS1 interacted with ZEB2 to
protect ZEB2 protein stability in the activation of the EMT signalling
pathw ay.
4.2.2 | Notch signalling pathway
The Notch signalling pat hway functions as a vital regulator in embr yo
development via the regulation of intercellular signal communication
by modifying cell proliferation and apoptosis42-4 4; both Hes- 1 and
NICD have vital functions in Notch signalling pathway.44,45 Gao et al
found that the expression Notch signal- related proteins Hes- 1 and
NICD were decreased by silencing ZFAS1in glioma cell, suggesting
ZFAS1 could regulate the expression of Hes- 1 and NICD to activate
Notch signalling pathway (Figure 2E).
4.2.3 | p53 signalling pathway
The p53 protein, a nuclear transcription factor, modified the expres-
sion of multiple genes which are involved in a variet y of biological
processes, including the cell c ycle, apoptosis, and DNA repair.46
Thorenoor et al demonstrated that decreased ZFAS1 contributed to
cell- cycle arrest and induction of apoptosis by reducing the expres-
sion of p53 and cyclin B1 and promoting PARP cleavage (Figure 2F).
This finding suggests that ZFAS1 activated the p53 signalling path-
way to act oncogenic roles in various cancers.
5 | CONCLUSION AND FUTURE
PERSPECTIVES
With the rapid development of next- generation sequencing tech-
nology, a large amount of evidence has identified dysregulated
lncRNAs as potential oncogenes or tumour suppressor genes that
play crucial regulatory roles in tumourigenesis and tumour progres-
sion.47, 48 ZFAS1, a newly identified lncRNA, was found to be widely
upregulated in various human cancers (expect breast cancer).
Amplified ZFAS1 was dramatically correlated with multiple clinico-
pathological features and prognosis, such as TNM stage, lymph-
node metastasis, and overall survival. In vitro, knockdown of ZFAS1
repressed cell proliferation, invasion, and promoted cell apoptosis
in multiple cancers, suggesting ZFAS1 contributed to tumourigen-
esis and tumour progression. In vivo experiments also confirmed
that silencing ZFAS1 could obviously restrain tumourigenesis of
cancer cells. The underlying molecular mechanisms of ZFAS1 in-
volved in multiple cancers have been explored preliminarily. At the
molecular level, ZFAS1 could function as a ceRNA in the regulation
of specific gene expression by competing for specific microRNAs,
representing its oncogenic function in various cancers. ZFAS1 also
could interact with some proteins to regulate gene expression at
the transcriptional level. Fur thermore, ZFAS1 was demonstrated to
take part in several signalling pathways contributing to c arcinogen-
esis and cancer progression, including EMT, Notch, and p53 signal-
ling pathways.
Although some of the underlying mechanisms of ZFAS1 in-
volved in dif ferent cancers have been identified, there are many
problems that still need to be addressed. First, the molecular
mechanism of ZFAS1 in each cancer type should be clarified. Many
lncRNAs function at the epigenetic, transcriptional, and post-
translational processing level in their contribution to carcinogene-
sis and cancer progression. Second, finding a diagnostic biomarker
or therapeutic target is a promising direction for cancer diagnosis
and treatment. Recently, several lncRNAs have been identified not
only in neoplastic tissues but also in body fluids, such as plasma
and urine, suggesting a potential role as cancer- specific molecular

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biomarkers in cancer diagnosis, prognosis, and treatment. Other
advantages in cancer diagnosis and treatment, especially in the
early diagnosis and prediction of prognosis, include simple and
noninvasive detection as well as a moderate treatment price.
Therefore, the clinical value of ZFAS1 in the diagnosis and treat-
ment of cancers requires more attention.
In summar y, ZFAS1 has been shown to have oncogenic function
in tumourigenesis and tumour progression and may act as a poten-
tial cancer- specific molecular biomarker in the general diagnosis,
prognosis, and treatment of cancer. Until this point, research on the
mechanism of ZFAS1 has made some progression, but remains in the
early st ages. Future works will need to emphasize exploration of the
precise molecular regulatory mechanisms of ZFAS1 in carcinogen-
esis and cancer progression, to facilitate the clinical applic ation of
ZFAS1 as early as possible.
ACKNOWLEDGEMENTS
This work was supported by National Natural Science Foundation of
China 81672546, 81602253, 81372746, Natural Science Foundation
of Beijing 71772219, 7152146, The Sh enzhen Municipa l Government
of China (ZDSYS201504301722174, JCYJ20150330102720130,
GJHZ20150316154912494).
AUTHORS’ CONTRIBUTIONS
AH, SH wrote the manuscript. XL and LZ provided the financial sup-
port and reviewed the manuscript. All authors read and approved
the final manuscript.
CONFLICT OF INTEREST
All authors declare no conflict of interest.
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How to cite this article: He A, He S, Li X, Zhou L . ZFAS1: A
novel vital oncogenic lncRNA in multiple human cancers. Cell
Prolif. 2019;52:e12513 . https://doi.o rg /10.1111/cpr.1 2513