Gene Summary

Gene:ATG7; autophagy related 7
Aliases: GSA7, APG7L, APG7-LIKE
Summary:This gene encodes an E1-like activating enzyme that is essential for autophagy and cytoplasmic to vacuole transport. The encoded protein is also thought to modulate p53-dependent cell cycle pathways during prolonged metabolic stress. It has been associated with multiple functions, including axon membrane trafficking, axonal homeostasis, mitophagy, adipose differentiation, and hematopoietic stem cell maintenance. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Sep 2015]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:ubiquitin-like modifier-activating enzyme ATG7
Source:NCBIAccessed: 01 September, 2019


What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 02 September 2019 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

Tag cloud generated 01 September, 2019 using data from PubMed, MeSH and CancerIndex

Specific Cancers (4)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: ATG7 (cancer-related)

Zhang H, Luo C, Zhang G
DNA Cell Biol. 2019; 38(8):857-864 [PubMed] Related Publications
Hepatocellular carcinoma (HCC) has been reported to be one of the major tumors in the world. There is a study indicating that MCM3AP-AS1 is an oncogenic factor in HCC; however, the mechanism by which MCM3AP-AS1 regulates HCC remains not fully understood. Reverse Transcription-quantitative PCR and Western blot approaches were used to detect mRNA and protein levels of various genes. To examine invasion of HCC cells and lymphatic vessel formation of human dermal lymphatic endothelial cells (HDLECs), we employed transwell invasion assay and lymphatic vessel assay. Bioinformatic analysis and luciferase reporter assay were used to establish direct interactions between MCM3AP-AS1 and miR-455. Besides, The Cancer Genome Atlas analyses of HCCs were performed to determine the association of MCM3AP-AS1 and epidermal growth factor receptor (EGFR) with overall survival. MCM3AP-AS1 knockdown impaired invasion of HCC cells and lymphatic vessel formation of HDLECs. MCM3AP-AS1 directly interacted with miR-455. Furthermore, miR-455 inhibitor-transfected HepG2 cells enhanced the invasion and lymphatic vessel formation abilities. The rescue experiments indicated that EGFR was critical for MCM3AP-AS1- and miR-455-regulated invasion and lymphatic vessel formation. More interestingly, autophagy-related genes (Beclin1, LC3 II/I, and ATG7) were abnormally regulated in miR-455 mimic or inhibitor HepG2 cells. miR-455 mimic inhibited cell invasion and lymphatic vessel formation, which was evidently abrogated by ATG7 overexpression. Finally, we analyzed The Cancer Genome Atlas data sets to test the upregulated expression levels of MCM3AP-AS1 and EGFR. In addition, the results showed that low levels of both genes facilitate survival of HCC patients. In this study, we reveal a novel mechanism underlying MCM3AP-AS1-induced HCC metastasis by regulating miR-455. The conclusions provide more insights into understanding mechanism underlying HCC and help development of therapeutical approaches for treating HCC.

Yang L, Song L, Zhao S, et al.
Isobavachalcone reveals novel characteristics of methuosis-like cell death in leukemia cells.
Chem Biol Interact. 2019; 304:131-138 [PubMed] Related Publications
Non-apoptotic cell-death induction is a potential strategy for cancer treatment. Cytoplasmic vacuolation-associated cell death represents a novel type of non-apoptotic cell-death. Here, we showed that isobavachalcone (IBC), a naturally occurring chalcone compound, selectively induced cell death with massive cytoplasmic vacuolation in some leukemic cells but not in normal peripheral blood cells. Although the IBC-induced cell death displayed certain apoptotic changes, the caspase inhibitor Z-VAD-FMK did not significantly suppress IBC-induced cell death. IBC-induced vacuoles are acidic in nature, as revealed by neutral red staining. However, these vacuoles could not be labeled by lysosome or mitochondrial trackers. Moreover, the knockdown of several autophagy-related genes, such as LC3, Beclin-1, and ATG7, did not inhibit IBC-induced vacuolation. Transmission electron microscope examination revealed that these vacuoles mainly derived from the endosome. Surprisingly, Vacuolar-type H + -ATPase inhibitors, weak bases, such as chloroquine and AKT inhibitors, markedly abrogated vacuolization but enhance IBC-induced cell death, suggesting that IBC-induced vacuolation and cell death go into different direction and the vacuolization is a protective action rather than a part of the death mechanism. In conclusion, by using IBC as a chemical probe, we provide new characteristics of methuosis-like cell death. Inducing methuosis-like cell death may represent a novel strategy to combat leukemia.

Shinde A, Hardy SD, Kim D, et al.
Spleen Tyrosine Kinase-Mediated Autophagy Is Required for Epithelial-Mesenchymal Plasticity and Metastasis in Breast Cancer.
Cancer Res. 2019; 79(8):1831-1843 [PubMed] Article available free on PMC after 15/04/2020 Related Publications
The ability of breast cancer cells to transiently transition between epithelial and mesenchymal states contributes to their metastatic potential. Therefore, driving tumor cells into a stable mesenchymal state, as opposed to complete tumor cell eradication, presents an opportunity to pharmacologically limit disease progression by promoting an asymptomatic state of dormancy. Here, we compare a reversible model of epithelial-mesenchymal transition (EMT) induced by TGFβ to a stable mesenchymal phenotype induced by chronic exposure to the ErbB kinase inhibitor lapatinib. Only cells capable of returning to an epithelial phenotype resulted in skeletal metastasis. Gene expression analyses of the two mesenchymal states indicated similar transition expression profiles. A potently downregulated gene in both datasets was spleen tyrosine kinase (SYK). In contrast to this similar diminution in mRNA, kinome analyses using a peptide array and DNA-conjugated peptide substrates showed a robust increase in SYK activity upon TGFβ-induced EMT only. SYK was present in cytoplasmic RNA processing depots known as P-bodies formed during the onset of EMT, and SYK activity was required for autophagy-mediated clearance of P-bodies during mesenchymal-epithelial transition (MET). Genetic knockout of autophagy-related 7 (ATG7) or pharmacologic inhibition of SYK activity with fostamatinib, a clinically approved inhibitor of SYK, prevented P-body clearance and MET, inhibiting metastatic tumor outgrowth. Overall, this study suggests assessment of SYK activity as a biomarker for metastatic disease and the use of fostamatinib as a means to stabilize the latency of disseminated tumor cells. SIGNIFICANCE: These findings present inhibition of spleen tyrosine kinase as a therapeutic option to limit breast cancer metastasis by promoting systemic tumor dormancy.

Xia C, He Z, Liang S, et al.
Metformin combined with nelfinavir induces SIRT3/mROS-dependent autophagy in human cervical cancer cells and xenograft in nude mice.
Eur J Pharmacol. 2019; 848:62-69 [PubMed] Related Publications
The molecular mechanisms underlying the antineoplastic properties of metformin combined with nelfinavir remain elusive. To explore this question, transmission electron microscopy (TEM) was used to observe the combinatorial effect of inducing autophagosome formation in human cervical cancer cells. Western blotting respectively assayed protein expression of LC3I, LC3II, Beclin-1, Autophagy-related protein 7 (Atg7), Autophagy-related protein 3 (Atg3), NAD-dependent deacetylase sirtuin-3 (SIRT3) and major histocompatibility complex class I chain-related gene A (MICA). Lactate dehydrogenase (LDH) cytotoxicity assay evaluated natural killer (NK) cell cytotoxicity in the presence of metformin and nelfinavir in combination or each drug alone. Using tumor xenografts in a nude mouse model, antitumor efficacy of the drug combination was assessed. We found that the drug combination could induce autophagosome formation in human cervical cancer cells. The biomarker proteins of autophagy, including Beclin-1, Atg7 and Atg3, decreased, but the ratios of LC3I/II increased. We also found that this drug combination sensitizes human cervical cancer cells to NK cell-mediated lysis by increasing the protein of SIRT3 and MICA. Moreover, this drug combination markedly induced autophagy of SiHa xenografts in nude mice. Therefore, it can be concluded that metformin, in combination with nelfinavir, can induce SIRT3/mROS-dependent autophagy and sensitize NK cell-mediated lysis in human cervical cancer cells and cervical cancer cell xenografts in nude mice. Thus, our findings have revealed the detailed molecular mechanisms underlying the antitumor effects of metformin in combination with nelfinavir in cervical cancer.

Bhatt V, Khayati K, Hu ZS, et al.
Autophagy modulates lipid metabolism to maintain metabolic flexibility for
Genes Dev. 2019; 33(3-4):150-165 [PubMed] Article available free on PMC after 15/04/2020 Related Publications
Loss of tumor suppressor liver kinase B1 (LKB1) promotes cancer cell proliferation but also leads to decreased metabolic plasticity in dealing with energy crises. Autophagy is a protective process involving self-cannibalization to maintain cellular energy homeostasis during nutrient deprivation. We developed a mouse model for

Zhu J, Huang G, Hua X, et al.
CD44s is a crucial ATG7 downstream regulator for stem-like property, invasion, and lung metastasis of human bladder cancer (BC) cells.
Oncogene. 2019; 38(17):3301-3315 [PubMed] Related Publications
Over half a million US residents are suffering with bladder cancer (BC), which costs a total $4 billion in treatment annually. Although recent studies report that autophagy-related gene 7 (ATG7) is overexpressed in BCs, the regulatory effects of ATG7 on cancer stem-like phenotypes and invasion have not been explored yet. Current studies demonstrated that the deficiency of ATG7 by its shRNA dramatically reduced sphere formation and invasion in vitro, as well as lung metastasis in vivo in human invasive BC cells. Further studies indicated that the knockdown of ATG7 attenuated the expression of CD44 standard (CD44s), while ectopic introduction of CD44s, was capable of completely restoring sphere formation, invasion, and lung metastasis in T24T(shATG7) cells. Mechanistic studies revealed that ATG7 overexpression stabilized CD44s proteins accompanied with upregulating USP28 proteins. Upregulated USP28 was able to bind to CD44s and remove the ubiquitin group from CD44s' protein, resulting in the stabilization of CD44s protein. Moreover, ATG7 inhibition stabilized AUF1 protein and thereby reduced tet1 mRNA stability and expression, which was able to demethylate usp28 promoter, reduced USP28 expression, finally promoting CD44s degradation. In addition, CD44s was defined to inhibit degradation of RhoGDIβ, which in turn promotes BC invasion. Our results demonstrate that CD44s is a key ATG7 downstream regulator of the sphere formation, invasion, and lung metastasis of BCs, providing significant insight into understanding the BC invasions, metastasis, and stem-like properties.

Ju S, Liang Z, Li C, et al.
The effect and mechanism of miR-210 in down-regulating the autophagy of lung cancer cells.
Pathol Res Pract. 2019; 215(3):453-458 [PubMed] Related Publications
This project aims to investigate the roles of miR-210 in autophagy of lung cancer cells and the related mechanism. The expressions of miR-210 and ATG7 in 30 cancer tissues and the adjacent tissues in patients with lung cancer were compared using RT-qPCR methods, Western Blot assay was carried out to test the expression of ATG7 in protein. Moreover, the dual luciferase reporter gene assay system was used to confirm ATG7 is a target gene of miR-210. Furthermore, lung cancer cell line A549 was transfected with either miR-210 mimics or inhibitors and RT-qPCR methods was used to detect the expression of miR-210 and ATG7. Next, MTT assay was used to examine the effect of miR-210 on the growth of the lung cancer cells, and finally, the expression of autophagy related genes, ATG7, LC3-II/LC3-I and Beclin-1 were detected by Western Blot and ICC assay. We observed that miR-210 was significantly increased and ATG7 was markedly decreased in cancer tissue of patients with lung cancer compared with normal tissue. Moreover, results of dual luciferase reporter assay indicated that ATG7 is a direct target of miR-210. Next, transfection of miR-210 mimics in lung cancer cells induced significant increase in cell proliferation, and transfection of miR-210 inhibitors lead to inhibited cell proliferation. Furthermore, over-expression of miR-210 induced marked decrease in the expression of ATG7, LC3-II/LC3-I and Beclin-1, while transfection of miR-210 inhibitors induced significant increase in the expression of ATG7, LC3-II/LC3-I and beclin-1. Our results suggested that miR-210 plays a great role in autophagy of lung cancer cell by targeting ATG7.

Zhang J, Mao S, Wang L, et al.
MicroRNA‑154 functions as a tumor suppressor in bladder cancer by directly targeting ATG7.
Oncol Rep. 2019; 41(2):819-828 [PubMed] Article available free on PMC after 15/04/2020 Related Publications
Aberrant expression of miR‑154 is usually found in cancer studies; however, the role of miR‑154 has seldom been reported in bladder cancer (BCa). In this study, we observed that miR‑154 expression was significantly downregulated in BCa tissues and cell lines, and was associated with several clinicopathological characteristics, including advanced T stage, lymphatic invasion, and distant metastasis. Low expression level of miR‑154 was associated with poor survival outcomes in BCa patients. Overexpression of miR‑154 led to significant decrease in the proliferation, migration, and invasion of BCa cells, while knockdown of miR‑154 yielded the opposite effect. ATG7 was identified as a direct target of miR‑154. ATG7 expression was negatively correlated with miR‑154 expression in BCa tissues. Silencing of ATG7 achieved a similar effect to miR‑154 overexpression; overexpression of ATG7 reversed the inhibitory effect of miR‑154 on BCa cell proliferation, migration and invasion. A xenograft study revealed that miR‑154 inhibited BCa cell growth in vivo, and suppressed ATG7 expression. Altogether, this study demonstrated that miR‑154 may function as a tumor suppressor in BCa and indicated that miR‑154 may be a potential therapeutic target for BCa patients.

Huang FX, Chen HJ, Zheng FX, et al.
LncRNA BLACAT1 is involved in chemoresistance of non‑small cell lung cancer cells by regulating autophagy.
Int J Oncol. 2019; 54(1):339-347 [PubMed] Related Publications
The aim of the present study was to determine the effect of the long non‑coding RNA (lncRNA) bladder cancer‑associated transcript 1 (BLACAT1) in chemoresistance of non‑small cell lung cancer (NSCLC) cells. Expression of lncRNA BLACAT1, microRNA (miR)‑17, autophagy‑related protein 7 (ATG7), multidrug‑resistance protein 1 (MRP1), and the autophagy‑associated proteins light chain 3 (LC3)‑II/LC3‑I and Beclin 1 were detected using the reverse transcription‑quantitative polymerase chain reaction and western blot analysis. Cell viability was determined using an MTT assay. The interaction between BLACAT1 and miR‑17 was determined using RNA immunoprecipitation and RNA pull‑down assays. A cisplatin (DDP)‑resistant NSCLC cell A549/DDP xenograft model in nude mice was established to investigate the effect of BLACAT1 on the chemoresistance of NSCLC cells. Compared with in DDP‑sensitive NSCLC cells, expression of BLACAT1, ATG7, MRP1, LC3‑II/LC3‑I and Beclin 1 was significantly upregulated in DDP‑resistant NSCLC cells, whereas miR‑17 was downregulated in DDP‑resistant NSCLC cells. Short interfering RNA against BLACAT1 decreased the viability of DDP‑resistant NSCLC cells. In addition, BLACAT1 interacted with miR‑17, and negatively regulated miR‑17. BLACAT1 promoted ATG7 expression through miR‑17, and facilitated autophagy and promoted chemoresistance of NSCLC cells through miR‑17/ATG7. Finally, in vivo experiments indicated that inhibition of BLACAT1 ameliorated the chemoresistance of NSCLC. BLACAT1 was upregulated in DDP‑resistant NSCLC cells, and promoted autophagy and chemoresistance of NSCLC cells through the miR‑17/ATG7 signaling pathway.

Gil J, Ramsey D, Pawlowski P, et al.
The Influence of Tumor Microenvironment on ATG4D Gene Expression in Colorectal Cancer Patients.
Med Oncol. 2018; 35(12):159 [PubMed] Article available free on PMC after 15/04/2020 Related Publications
Despite great progress in research on the subject, the involvement of autophagy in colorectal cancer (CRC) pathogenesis (initiation, progression, metastasis) remains obscure and controversial. Autophagy is a catabolic process, fundamental to cell viability and connected with degradation/recycling of proteins and organelles. In this study, we aimed at investigating the relative expression level of mRNA via Real-Time PCR of 16 chosen genes belonging to Atg8 mammalian orthologs and their conjugation system, comprising GABARAP, GABARAPL1, GABARAPL2, MAP1LC3A, MAP1LC3B, MAP1LC3C, ATG3, ATG7, ATG10, ATG4A, ATG4B, ATG4C, ATG4D, and three genes encoding proteins building the multimeric ATG16L1 complex, namely ATG5, ATG12, and ATG16L1, in 73 colorectal tumors and paired adjacent normal colon mucosa. Our study demonstrated the relative downregulation of all examined genes in CRC tissues in comparison to adjacent noncancerous mucosa, with the highest rate of expression in both tumor and non-tumor tissues observed for GAPARBPL2 and the lowest for MAP1LC3C. Moreover, in patients with advanced-stage tumors and high values of regional lymph nodes, statistically significant downregulation of ATG4D expression in adjacent normal cells was observed. Our study confirms the role of autophagy genes as cancer suppressors in colorectal carcinogenesis. Furthermore, in regard to the ATG4D gene, we observed the influence of tumor microenvironments on gene expression in adjacent colon mucosa.

Batool S, Joseph TP, Hussain M, et al.
LP1 from
Int J Mol Sci. 2018; 19(10) [PubMed] Article available free on PMC after 15/04/2020 Related Publications
Present study aimed to elucidate the anticancer effect and the possible molecular mechanism underlying the action of Latcripin 1 (LP1), from the mushroom

Jayasooriya RGPT, Dilshara MG, Karunarathne WAHM, et al.
Camptothecin enhances c-Myc-mediated endoplasmic reticulum stress and leads to autophagy by activating Ca
Food Chem Toxicol. 2018; 121:648-656 [PubMed] Related Publications
Camptothecin (CPT) from Camptotheca acuminate was discovered for anticancer drugs, which targets topoisomease I. However, whether CPT regulates c-Myc expression has not been understood in endoplasmic reticulum (ER) stress and autophagy. In this study, we found that CPT enhanced c-Myc expression and that the transient knockdown of c-Myc abrogated reactive oxygen species (ROS) generation, which resulted in the accumulation of ER stress-regulating proteins, such as PERK, eIF2α, ATF4, and CHOP. Moreover, the transfection of eIF2α-targeted siRNA attenuated CPT-induced autophagy and decreased the levels of Beclin-1 and Atg7, which indicated that CPT upregulated ER stress-mediated autophagy. In addition, CPT phosphorylated AMPK in response to intracellular Ca

Kim JC, Ha YJ, Tak KH, et al.
Opposite functions of GSN and OAS2 on colorectal cancer metastasis, mediating perineural and lymphovascular invasion, respectively.
PLoS One. 2018; 13(8):e0202856 [PubMed] Article available free on PMC after 15/04/2020 Related Publications
The present study aimed to identify molecules associated with lymphovascular invasion (LVI) and perineural invasion (PNI) and to examine their biological behavior in colorectal cancer (CRC). LVI- and PNI-associated molecules were identified and verified using sequential processes including (1) identification of 117 recurrence-associated genes differentially expressed on RNA-seq analysis using primary cancer tissues from 130 CRC patients with and without systemic recurrence; (2) analysis of molecules associated with LVI and PNI; (3) assessment of biological properties by measuring proliferation, anoikis, invasion/migration, epithelial-mesenchymal transition and autophagy flux; and (4) verification of disease-free survival using public datasets. Gelsolin (GSN) and 2'-5'-oligoadenylate synthetase 2 (OAS2) were associated with PNI and LVI, respectively. Invasion potential was >2-fold greater in GSN-overexpressing LoVo cells than in control cells (p<0.001-0.005), whereas OAS2-overexpressing RKO cells showed reduced invasion (p<0.001-0.005). GSN downregulated E-cadherin, β-catenin, claudin-1 and snail, and upregulated N-cadherin and ZEB1, whereas OAS2 overexpression had the opposite effects. Several autophagy-related proteins including ATG5-12, ATG6/BECN1, ATG7 and ATG101 were downregulated in GSN-overexpressing LoVo cells, whereas the opposite pattern was observed in OAS2-overexpressing RKO cells. Patients with low GSN expression had significantly higher 5-year recurrence-free survival (RFS) rates than those with GSN overexpression (73.6% vs. 64.7%, p = 0.038), whereas RFS was longer in patients with OAS2 overexpression than in those with underexpression (73.4% vs. 63.7%, p = 0.01). In conclusion, GSN and OAS2 were positively and negatively associated with recurrence, respectively, suggesting their potential value as predictors of recurrence or therapeutic targets in CRC patients.

Wang X, Liu W, Wang P, Li S
RNA interference of long noncoding RNA HOTAIR suppresses autophagy and promotes apoptosis and sensitivity to cisplatin in oral squamous cell carcinoma.
J Oral Pathol Med. 2018; 47(10):930-937 [PubMed] Related Publications
BACKGROUND: Long noncoding RNA HOX transcript antisense RNA (lncRNA HOTAIR) is overexpressed in many types of human cancers and is correlated with clinical stage and lymph node metastasis in oral squamous cell carcinoma (OSCC). Autophagy, an important mechanism of self-protection, plays vital roles in adapting to hypoxia, tolerating external stimulation, and inducing chemotherapy resistance in OSCC cells. This study aims to investigate the effect of HOTAIR on autophagy, apoptosis, and invasion of OSCC cells.
METHODS: HOTAIR expression in OSCC cells was knocked down by small RNA interference. Transmission electron microscope, Western blot, and flow cytometry assay were used to detect the level of autophagy and apoptosis. OSCC cells were medicated with cisplatin, and median lethal dose (LD50) was performed to evaluate the effect on chemosensitivity of HOTAIR.
RESULTS: After HOTAIR silence, autophagy was inhibited with the downregulated expression of MAP1LC3B (microtubule-associated protein 1 light chain 3B), beclin1, and autophagy-related gene (ATG) 3 and ATG7. The expressions of mTOR increased. Proliferation, migration, and invasion of OSCC cells were suppressed. Furthermore, apoptosis rate was enhanced, and the sensitivity to cisplatin was promoted when compared with the negative control group.
CONCLUSION: HOTAIR acts as an oncogene in OSCC cells, and HOTAIR silence may be a potential therapeutic target for OSCC.

Wang S, Wu J, Ren J, et al.
MicroRNA-125b Interacts with Foxp3 to Induce Autophagy in Thyroid Cancer.
Mol Ther. 2018; 26(9):2295-2303 [PubMed] Article available free on PMC after 05/09/2019 Related Publications
Thyroid cancer is rapidly increasing in incidence worldwide. Although most thyroid cancer can be cured with surgery, radioactive iodine, and/or chemotherapy, thyroid cancers still recur and may become chemoresistant. Autophagy is a complex self-degradative process that plays a dual role in cancer development and progression. In this study, we found that miR-125b was downregulated in tissue samples of thyroid cancer as well as in thyroid cancer cell lines, and the expression of Foxp3 was upregulated. Further, we demonstrated that miR-125b could directly act on Foxp3 by binding to its 3' UTR and inhibit the expression of Foxp3. A negative relationship between miR-125b and Foxp3 was thus revealed. Overexpression of miR-125b markedly sensitized thyroid cancer cells to cisplatin treatment by inducing autophagy through an Atg7 pathway in vitro and in vivo. Taken together, our findings demonstrate a novel mechanism by which miR-125b has the potential to negatively regulate Foxp3 to promote autophagy and enhance the efficacy of cisplatin in thyroid cancer. miR-125 may be of therapeutic significance in thyroid cancer.

Vera-Ramirez L, Vodnala SK, Nini R, et al.
Autophagy promotes the survival of dormant breast cancer cells and metastatic tumour recurrence.
Nat Commun. 2018; 9(1):1944 [PubMed] Article available free on PMC after 05/09/2019 Related Publications
Cancer recurrence after initial diagnosis and treatment is a major cause of breast cancer (BC) mortality, which results from the metastatic outbreak of dormant tumour cells. Alterations in the tumour microenvironment can trigger signalling pathways in dormant cells leading to their proliferation. However, processes involved in the initial and the long-term survival of disseminated dormant BC cells remain largely unknown. Here we show that autophagy is a critical mechanism for the survival of disseminated dormant BC cells. Pharmacologic or genetic inhibition of autophagy in dormant BC cells results in significantly decreased cell survival and metastatic burden in mouse and human 3D in vitro and in vivo preclinical models of dormancy. In vivo experiments identify autophagy gene autophagy-related 7 (ATG7) to be essential for autophagy activation. Mechanistically, inhibition of the autophagic flux in dormant BC cells leads to the accumulation of damaged mitochondria and reactive oxygen species (ROS), resulting in cell apoptosis.

Ou Y, He J, Liu Y
MiR-490-3p inhibits autophagy via targeting ATG7 in hepatocellular carcinoma.
IUBMB Life. 2018; 70(6):468-478 [PubMed] Related Publications
The miR-490-3p was transfected into HepG2 cells to explore the correlation between miR-490-3p and hepatocellular carcinoma cell proliferation, apoptosis, and autophagy and its downstream target gene ATG7. Then we could possibly provide a mechanism for the treatment of hepatocellular carcinoma. MiR-490-3p was screened out by fold change > 4 and P < 0.01 using gene microarray data. The expression level of miR-490-3p was tested by qRT-PCR and the prognosis analysis was achieved by using TCGA data. The cell proliferation was tested via colony formation assay and CCK-8 after the miR-490-3p mimics were transfected into HepG2 cells; the variations of cell cycle and apoptosis was examined by flow cytometry assay; the number of autophagosome was observed by electron microscopy and the changes of autophagy-relative protein LC-II and LC-I as well as their ratio was tested by western blot. MiR-490-3p is low expressed in hepatocellular carcinoma cell lines and tissues. The results of TCGA showed that miR-490-3p high expression indicated better prognosis. After HepG2 cells were transfected with miR-490-3p mimics, cell viability was increased, cell proliferation was enhanced, cell cycle was blocked in G0/G1 phase, cell apoptosis rate was increased, the number of autophagosomes was reduced, autophagy-associated protein LC-II was decreased, and LC-I was increased and their ratio was decreased. After 3-MA was added, cell proliferation was declined, cell apoptosis rate was increased. Besides, the autophagy was inhibited by knocking down the ATG7, which promoted the cell apoptosis. MiR-490-3p could suppress cell proliferation, retard cell cycle and upgrade cell apoptosis by inhibiting autophagy in HCC cells via targeting ATG7. © 2018 IUBMB Life, 70(6):468-478, 2018.

Walker A, Singh A, Tully E, et al.
Nrf2 signaling and autophagy are complementary in protecting breast cancer cells during glucose deprivation.
Free Radic Biol Med. 2018; 120:407-413 [PubMed] Article available free on PMC after 05/09/2019 Related Publications
Autophagy can serve as a mechanism for survival of cells during nutrient deprivation by recycling cellular macromolecules and organelles transiently to provide essential metabolic substrates. However, autophagy itself causes metabolic stress to cells, and other cellular protective mechanisms likely cooperate with autophagy to promote cell survival during nutrient deprivation. In this study, we explored protective mechanisms in breast cancer cells in the setting of glucose deprivation. While breast cancer cells (MCF7 and T47D) survive in glucose-free medium for three days or more, autophagy is induced in this setting. Blocking autophagy pharmacologically with chloroquine or by knock-out of an essential autophagy gene, such as Beclin 1 or ATG7, markedly reduces the ability of cells to survive during glucose deprivation. Autophagy previously was shown to degrade p62, a protein that sequesters KEAP1, and KEAP1 in turn sequesters Nrf2, a master regulator of the antioxidant response. Hence, we investigated how the Nrf2 signaling pathway might be affected by glucose deprivation and autophagy. We found that while glucose deprivation does cause decreased cellular levels of p62, Nrf2 protein levels and activity unexpectedly increase in this setting. Moreover, this increase in Nrf2 activity provides important protection to breast cancer cells during glucose deprivation, since siRNA knockdown of Nrf2 markedly impairs survival during glucose deprivation. Antioxidants, N-acetyl cysteine and glutathione also protect these cells during glucose deprivation, leading us to conclude that Nrf2 signaling via its antioxidant activity has a critical and previously undescribed role of protecting cells during glucose deprivation-induced autophagy.

Cai J, Li R, Xu X, et al.
CK1α suppresses lung tumour growth by stabilizing PTEN and inducing autophagy.
Nat Cell Biol. 2018; 20(4):465-478 [PubMed] Related Publications
The contribution of autophagy to cancer development remains controversial, largely owing to the fact that autophagy can be tumour suppressive or oncogenic in different biological contexts. Here, we show that in non-small-cell lung cancer (NSCLC), casein kinase 1 alpha 1 (CK1α) suppresses tumour growth by functioning as an autophagy inducer to activate an autophagy-regulating, tumour-suppressive PTEN/AKT/FOXO3a/Atg7 axis. Specifically, CK1α bound the C-terminal tail of PTEN and enhanced both PTEN stability and activity by competitively antagonizing NEDD4-1-induced PTEN polyubiquitination and abrogating PTEN phosphorylation, thereby inhibiting AKT activity and activating FOXO3a-induced transcription of Atg7. Notably, blocking CK1α-induced Atg7-dependent autophagy cooperates with oncogenic HRas

Tsai TC, Lai KH, Su JH, et al.
7-Acetylsinumaximol B Induces Apoptosis and Autophagy in Human Gastric Carcinoma Cells through Mitochondria Dysfunction and Activation of the PERK/eIF2α/ATF4/CHOP Signaling Pathway.
Mar Drugs. 2018; 16(4) [PubMed] Article available free on PMC after 05/09/2019 Related Publications
The 7-Acetylsinumaximol B (7-AB), a bioactive cembranoid, was originally discovered from aquaculture soft coral

Xu W, Song F, Wang B, et al.
The Effect of and Mechanism Underlying Autophagy in Hepatocellular Carcinoma Induced by CH12, a Monoclonal Antibody Directed Against Epidermal Growth Factor Receptor Variant III.
Cell Physiol Biochem. 2018; 46(1):226-237 [PubMed] Related Publications
BACKGROUND/AIMS: Epidermal growth factor receptor variant III (EGFRvIII), the most frequent EGFR variant, is constitutively activated without binding to EGF and is correlated with a poor prognosis. CH12, a human-mouse chimeric monoclonal antibody, has been developed in our laboratory and selectively binds to overexpressed EGFR and EGFRvIII. A previous study had reported that EGFR could influence autophagic activity, and autophagy is closely related to tumor development and the response to drug therapy. In this study, we aimed to elucidate the effect of CH12 on autophagy and efficacy of combining CH12 with an autophagy inhibitor against EGFRvIII-positive tumors.
METHODS: EGFRvIII was overexpressed in liver cancer, glioblastoma and breast cancer, and the change in the autophagy-relevant protein levels was analyzed by western blot assays, LC3 punctate aggregation was analyzed by immunofluorescence. The interaction of Beclin-1 and Rubicon was assessed by co-immunoprecipitation (Co-IP) after CH12 treatment. The efficacy of ATG7 or Beclin-1 siRNA in combination with CH12 in Huh-7-EGFRvIII cells was assessed by CCK-8 assays. The autophagy and apoptosis signaling events in Huh-7-EGFRvIII cells upon treatment with control, CH12, siRNA or combination for 48 h were assessed by western blot assays.
RESULTS: Our results showed that, in cancer cell lines overexpressing EGFRvIII, only the liver cancer cell lines Huh-7 and PLC/PRF/5 suggested autophagy activation. We then investigated the mechanism of autophagy activation after EGFRvIII overexpression. The results showed that EGFRvIII interacted with Rubicon, an autophagy inhibition protein, and released Beclin-1 to form the inducer complex, thus contributing to autophagy. In addition, CH12, via inhibiting the phosphorylation of EGFRvIII, promoted the interaction of EGFRvIII with Rubicon, further inducing autophagy. In vitro assays suggested that knocking down the expression of the key proteins ATG7 or Beclin-1 in the autophagy pathway with siRNA inhibits tumor cell proliferation. Combining autophagy-related proteins 7 (ATG7) or Beclin-1 siRNA with CH12 in Huh-7-EGFRvIII cells showed better inhibition of cell proliferation.
CONCLUSION: EGFRvIII could induce autophagy, and CH12 treatment could improve autophagy activity in EGFRvIII-positive liver cancer cells. The combination of CH12 with an autophagy inhibitor or siRNA against key proteins in the autophagy pathway displayed more significant efficacy on EGFRvIII-positive tumor cells than monotherapy, and induced cell apoptosis.

Liu L, Shen W, Zhu Z, et al.
Combined inhibition of EGFR and c-ABL suppresses the growth of fulvestrant-resistant breast cancer cells through miR-375-autophagy axis.
Biochem Biophys Res Commun. 2018; 498(3):559-565 [PubMed] Related Publications
Fulvestrant is the FDA-approved "pure anti-estrogen" agent for malignant breast cancer therapy. But endocrine resistance causes drug failure. A new approach is desired for fulvestrant-resistant breast cancer (FRBC) therapy. This study aims to find an effective approach to inhibit FRBC for patients with advanced breast cancer. MTT assay was first performed to detect the effect of inhibitors of c-ABL (imatinib) and EGFR (lapatinib) on FRBC cells. Microarray analysis was carried out to identify microRNA which is significantly changed between parental and FRBC cells. The related mechanisms were analyzed by qRT-PCR, MTT, AO staining and western blotting. Dual treatment significantly inhibited cell growth of FRBC and upregulated microRNA-375 (miR-375). Overexpression of miR-375 inhibited growth of FRBC cells, reduced autophagy, and decreased expression of ATG7 and LC3-II. Dual treatment elevated expression of miR-375 more than any single one of these two inhibitors. Overexpression of miR-375 increased cell growth inhibition induced by dual treatment, and the effect was attenuated when miR-375 was inhibited. In conclusion, we identified that combined inhibition of EGFR and c-ABL can suppress the growth of FRBC cells and elucidated a mechanism within FRBC cells involving regulation of miR-375 and autophagy. Dual treatment may be useful for inhibiting fulvestrant-resistant breast cancer.

Chen J, Zhang L, Zhou H, et al.
Inhibition of autophagy promotes cisplatin-induced apoptotic cell death through Atg5 and Beclin 1 in A549 human lung cancer cells.
Mol Med Rep. 2018; 17(5):6859-6865 [PubMed] Related Publications
Recent studies have indicated that autophagy contributes to tumorigenesis and participates in acquired chemotherapeutic resistance. The present study aimed to determine the function and underlying mechanism of cisplatin‑induced autophagy in A549 human lung cancer cells. Autophagy was measured by LC3B‑I/II conversion, LC3B puncta and autophagosomes formation. Apoptotic cell death was measured by caspase‑3 activity, caspase‑3 cleavage and LDH release. The transcriptional and expressional level of autophagy related proteins were measured by reverse transcription-quantitative polymerase chain reaction and western blot analysis. Beclin 1 and Atg 5 siRNA transfection was used to explore the function of cisplatin‑induced autophagy. The results demonstrated that cisplatin induces apoptotic cell death in A549 cells and triggers an autophagic response, as indicated by increased microtubule‑associated protein 1 light chain 3β (LC3B)‑I/II conversion, increased LC3B puncta and autophagosome formation. Mechanisms underlying cisplatin‑induced autophagic responses were also investigated. Cisplatin induced autophagy by upregulating the mRNA and protein expression levels of autophagy protein (Atg)5 and Beclin 1, whereas the mRNA and protein expression levels of serine/threonine‑protein kinase ULK1, Atg3, Atg7, Atg12, and sequestosome‑1 were not markedly upregulated. In addition, knockdown of Atg5 and Beclin 1 by small interfering RNA transfection impaired cisplatin‑induced activation of autophagic responses, increased caspase‑3 cleavage and inhibited cell viability. These findings suggested that disruption of autophagy via the inhibition of Atg5 and Beclin 1 may promote cisplatin‑induced apoptotic cell death in A549 human lung cancer cells. In conclusion, the present study demonstrated that targeting autophagy may be used in the future for the treatment of lung cancer.

Alizadeh J, Glogowska A, Thliveris J, et al.
Autophagy modulates transforming growth factor beta 1 induced epithelial to mesenchymal transition in non-small cell lung cancer cells.
Biochim Biophys Acta Mol Cell Res. 2018; 1865(5):749-768 [PubMed] Related Publications
Lung cancer is considered one of the most frequent causes of cancer-related death worldwide and Non-Small Cell Lung Cancer (NSCLC) accounts for 80% of all lung cancer cases. Autophagy is a cellular process responsible for the recycling of damaged organelles and protein aggregates. Transforming growth factor beta-1 (TGFβ

He W, Zhang A, Qi L, et al.
FOXO1, a Potential Therapeutic Target, Regulates Autophagic Flux, Oxidative Stress, Mitochondrial Dysfunction, and Apoptosis in Human Cholangiocarcinoma QBC939 Cells.
Cell Physiol Biochem. 2018; 45(4):1506-1514 [PubMed] Related Publications
BACKGROUND/AIMS: Autophagy is an evolutionarily conserved catabolic mechanism to maintain energy homeostasis and to remove damaged cellular components, which plays an important role in the survival of various cells. Inhibiting autophagy is often applied as a new strategy to halt the growth of cancer cells.
METHODS: The effect of FOXO1 gene on cellular function and apoptosis and its underlying mechanisms were investigated in cultured QBC939 cells by the methylthiazoletetrazolium (MTT) assay, western blot, DCFDA mitochondrial membrane potential, and ATP content measurement. FOXO1 siRNA was applied to down-regulate FOXO1 expression in QBC939 cells.
RESULTS: Here we reported that FOXO1, acetylation of FOXO1 (Ac-FOXO1) and the following interaction between Ac-FOXO1 and Atg7 regulated the basal and serum starvation (SS)-induced autophagy as evidenced by light chain 3 (LC3) accumulation and p62 degration. Either treatment with FOXO1 siRNA or resveratrol, a sirt1 agonist, inhibited autophagic flux, resulting in oxidative stress, mitochondrial dysfunction (MtD) and apoptosis in QBC939 cells, which were attenuated by enhancing autophagy with rapamycin. On the contrary, inhibiting autophagic flux with 3-MA worsened all these effects in QBC939 cells.
CONCLUSIONS: Taken together, our study for the first time identified FOXO1 as a potential therapeutic target to cure against human cholangiocarcinoma via regulation of autophagy, oxidative stress and MtD.

Yuan J, Zhang N, Yin L, et al.
Clinical Implications of the Autophagy Core Gene Variations in Advanced Lung Adenocarcinoma Treated with Gefitinib.
Sci Rep. 2017; 7(1):17814 [PubMed] Article available free on PMC after 05/09/2019 Related Publications
EGFR-TKIs show dramatic treatment benefits for advanced lung adenocarcinoma patients with activating EGFR mutations. Considering the essential role of autophagy in EGFR-TKIs treatments, we hypothesized that genetic variants in autophagy core genes might contribute to outcomes of advanced lung adenocarcinoma treated with gefitinib. We systematically examined 27 potentially functional genetic polymorphisms in 11 autophagy core genes among 108 gefitinib-treated advanced lung adenocarcinoma patients. We found that ATG10 rs10036653, ATG12 rs26538, ATG16L1 rs2241880 and ATG16L2 rs11235604 were significantly associated with survival of lung adenocarcinoma patients (all P < 0.05). Among EGFR-mutant patients, ATG5 rs688810, ATG5 rs510432, ATG7 rs8154, ATG10 rs10036653, ATG12 rs26538, ATG16L1 rs2241880 and ATG16L2 rs11235604 significantly contributed to disease prognosis. We also found that ATG5 rs510432, ATG5 rs688810, ATG10 rs10036653 and ATG10 rs1864182 were associated with primary or acquired resistance to gefitinib. Functional analyses of ATG10 rs10036653 polymorphism suggested that ATG10 A allele might increase transcription factor OCT4 binding affinity compared to the T allele in lung cancer cells. Our results indicate that autophagy core genetic variants show potential clinical implications in gefitinib treatment, especially among advanced lung adenocarcinoma patients, highlighting the possibility of patient-tailored decisions during EGFR-TKIs based on both germline and somatic variation detection.

Guo H, Chitiprolu M, Roncevic L, et al.
Atg5 Disassociates the V
Dev Cell. 2017; 43(6):716-730.e7 [PubMed] Related Publications
Autophagy and autophagy-related genes (Atg) have been attributed prominent roles in tumorigenesis, tumor growth, and metastasis. Extracellular vesicles called exosomes are also implicated in cancer metastasis. Here, we demonstrate that exosome production is strongly reduced in cells lacking Atg5 and Atg16L1, but this is independent of Atg7 and canonical autophagy. Atg5 specifically decreases acidification of late endosomes where exosomes are produced, disrupting the acidifying V

Song X, Zhu S, Xie Y, et al.
JTC801 Induces pH-dependent Death Specifically in Cancer Cells and Slows Growth of Tumors in Mice.
Gastroenterology. 2018; 154(5):1480-1493 [PubMed] Article available free on PMC after 05/09/2019 Related Publications
BACKGROUND & AIMS: Maintenance of acid-base homeostasis is required for normal physiology, metabolism, and development. It is not clear how cell death is activated in response to changes in pH. We performed a screen to identify agents that induce cell death in a pH-dependent manner (we call this alkaliptosis) in pancreatic ductal adenocarcinoma cancer (PDAC) cells and tested their effects in mice.
METHODS: We screened a library of 254 compounds that interact with G-protein-coupled receptors (GPCRs) to identify those with cytotoxic activity against a human PDAC cell line (PANC1). We evaluated the ability of JTC801, which binds the opiod receptor and has analgesic effects, to stimulate cell death in human PDAC cell lines (PANC1, MiaPaCa2, CFPAC1, PANC2.03, BxPc3, and CAPAN2), mouse pancreatic cancer-associated stellate cell lines, primary human pancreatic ductal epithelial cells, and 60 cancer cell lines (the NCI-60 panel). Genes encoding proteins in cell death and GPCR signaling pathways, as well as those that regulate nuclear factor-κB (NF-κB) activity, were knocked out, knocked down, or expressed from transgenes in cancer cell lines. JTC801 was administered by gavage to mice with xenograft tumors, C57BL/6 mice with orthographic pancreatic tumors grown from Pdx1-Cre;KRas
RESULTS: Exposure of human PDAC cell lines (PANC1 and MiaPaCa2) to JTC801 did not induce molecular markers of apoptosis (cleavage of caspase 3 or poly [ADP ribose] polymerase [PARP]), necroptosis (interaction between receptor-interacting serine-threonine kinase 3 [RIPK3] and mixed lineage kinase domain like pseudokinase [MLKL]), or ferroptosis (degradation of glutathione peroxidase 4 [GPX4]). Inhibitors of apoptosis (Z-VAD-FMK), necroptosis (necrosulfonamide), ferroptosis (ferrostatin-1), or autophagy (hydroxychloroquine) did not prevent JTC801-induced death of PANC1 or MiaPaCa2 cells. The cytotoxic effects of JTC801 in immortalized fibroblast cell lines was not affected by disruption of genes that promote apoptosis (Bax
CONCLUSIONS: In a screen of agents that interact with GPCR pathways, we found JTC801 to induce pH-dependent cell death (alkaliptosis) specifically in cancer cells such as PDAC cells, by reducing expression of CA9. Levels of CA9 are increased in human cancer tissues. JTC801 might be developed for treatment of pancreatic cancer.

Li Y, Hu T, Chen T, et al.
Combination treatment of FTY720 and cisplatin exhibits enhanced antitumour effects on cisplatin-resistant non-small lung cancer cells.
Oncol Rep. 2018; 39(2):565-572 [PubMed] Related Publications
A major common medical treatment for lung carcinoma is cisplatin (DDP)-based therapy. However, the development or existence of chemoresistance frequently blocks its effectiveness. Currently, autophagy is recognised as a potential anticancer strategy, although there is controversy over its role in the development of cancer. In lung carcinoma, no studies of autophagy induced by FTY720, a sphingosine 1-phosphate analog and a novel immunosuppressant drug, have been published, while apoptosis has been shown to be induced by FTY720 in several cancer cell lines. We evaluated the effects of FTY720 on autophagy in A549 cells and studied the related mechanisms of cell autophagy and apoptosis in non-small cell lung carcinoma, including both DDP-resistant and -sensitive cells. The results revealed that FTY720 inhibited the growth and induced apoptosis in the A549/DDP cells in a time- and dose-dependent manner and the combination of FTY720 and DDP further enhanced apoptosis in these cells as determined by CCK-8 assay, western blotting and flow cytometry. Compared with the sensitive cell line A549, DDP-resistant A549/DDP cells showed a substantial increase in baseline autophagy as determined by increased LC puncta, and expression of LC3-I, LC3-II and Atg7 expression. DDP-induced apoptotic cell death was enhanced by the blockade of either siRNA-mediated knockdown of Atg7 genetic expression or a pharmacological inhibitor (3-MA). Moreover, the combination of FTY720 and DDP showed enhanced antitumour activity in vivo in lung cancer-bearing mice. Immunohistochemistry showed that the mice with lung carcinoma treated with FTY720 and DDP showed decreased expression of Atg7 and Ki67. Compared with monotherapy in vivo and in vitro, FTY720 in combination with DDP inhibited A549 cell growth more effectively. and these findings also show the influence of FTY720 in the induction of autophagy. Overall, the results indicated that FTY720 in combination with a DDP-based regime could enhance the effectiveness of lung carcinoma treatment.

Yang F, Yang L, Wataya-Kaneda M, et al.
Dysregulation of autophagy in melanocytes contributes to hypopigmented macules in tuberous sclerosis complex.
J Dermatol Sci. 2018; 89(2):155-164 [PubMed] Related Publications
BACKGROUND: Tuberous sclerosis complex (TSC) gene mutations lead to constitutive activation of the mammalian target of rapamycin (mTOR) pathway, resulting in a broad range of symptoms. Hypopigmented macules are the earliest sign. Although we have already confirmed that topical rapamycin treatment (an mTOR inhibitor) protects patients with TSC against macular hypopigmentation, the pathogenesis of such lesions remains poorly understood.
OBJECTIVE: Recently emerging evidence supports a role for autophagy in skin pigmentation. Herein, we investigated the impact of autophagic dysregulation on TSC-associated hypopigmentation.
METHODS: Skin samples from 10 patients with TSC, each bearing characteristic hypopigmented macules, and 6 healthy donors were subjected to immunohistochemical and electron microscopic analyses. In addition, TSC2-knockdown (KD) was investigated in human epidermal melanocytes by melanin content examination, real-time PCR, western blotting analyses, and intracellular immunofluorescence staining.
RESULTS: Activation of the mTOR signaling pathway decreased melanocytic pigmentation in hypopigmented macules of patients with TSC and in TSC2-KD melanocytes. In addition, LC3 expression (a marker of autophagy) and autophagosome counts increased, whereas, intracellular accumulation of autophagic degradative substrates (p62 and ubiquitinated proteins) was evident in TSC2-KD melanocytes. Furthermore, depigmentation in TSC2-KD melanocytes was accelerated by inhibiting autophagy (ATG7-KD or bafilomycin A1-pretreatment) and was completely reversed by induction of autophagy via mTOR-dependent (rapamycin) or mTOR-independent (SMER28) exposure. Finally, dysregulation of autophagy, marked by increased LC3 expression and accumulation of ubiquitinated proteins, was also observed in melanocytes of TSC-related hypopigmented macules.
CONCLUSION: Our data demonstrate that melanocytes of patients with TSC display autophagic dysregulation, which thereby reduced pigmentation, serving as the basis for the hypomelanotic macules characteristic of TSC.

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