DNA Damage-Response Pathway Heterogeneity of Human Lung Cancer A549 and H1299 Cells Determines Sensitivity to 8-Chloro-Adenosine.

Human lung cancer H1299 (p53-null) cells often display enhanced susceptibility to chemotherapeutics comparing to A549 (p53-wt) cells. However, little is known regarding to the association of DNA damage-response (DDR) pathway heterogeneity with drug sensitivity in these two cells. We investigated the DDR pathway differences between A549 and H1299 cells exposed to 8-chloro-adenosine (8-Cl-Ado), a potential anticancer drug that can induce DNA double-strand breaks (DSBs), and found that the hypersensitivity of H1299 cells to 8-Cl-Ado is associated with its DSB overaccumulation. The major causes of excessive DSBs in H1299 cells are as follows: First, defect of p53-p21 signal and phosphorylation of SMC1 increase S phase cells, where replication of DNA containing single-strand DNA break (SSB) produces more DSBs in H1299 cells. Second, p53 defect and no available induction of DNA repair protein p53R2 impair DNA repair activity in H1299 cells more severely than A549 cells. Third, cleavage of PARP-1 inhibits topoisomerase I and/or topoisomerase I-like activity of PARP-1, aggravates DNA DSBs and DNA repair mechanism impairment in H1299 cells. Together, DDR pathway heterogeneity of cancer cells is linked to cancer susceptibility to DNA damage-based chemotherapeutics, which may provide aid in design of chemotherapy strategy to improve treatment outcomes.

MiR-509-3-5p causes aberrant mitosis and anti-proliferative effect by suppression of PLK1 in human lung cancer A549 cells.

MicroRNAs (miRNAs) are potent post-transcriptional regulators of gene expression and play roles in DNA damage response (DDR). PLK1 is identified as a modulator of DNA damage checkpoint. Although down-regulation of PLK1 by certain microRNAs has been reported, little is known about the interplay between PLK1 and miR-509-3-5p in DDR. Here we have demonstrated that miR-509-3-5p repressed PLK1 expression by targeting PLK1 3'-UTR, thereby causing mitotic aberration and growth arrest of human lung cancer A549 cells. Repression of PLK1 by miR-509-3-5p was further evidenced by over-expression of miR-509-3-5p in A549, HepG2 and HCT116p53(-/-) cancer cells, in which PLK1 protein was suppressed. Consistently, miR-509-3-5p was stimulated, while PLK1 protein was down-regulated in A549 cells exposed to CIS and ADR, suggesting that suppression of PLK1 by miR-509-3-5p is a component of CIS/ADR-induced DDR pathway. Flow cytometry and immunofluorescence labeling showed that over-expression of miR-509-3-5p in A549 induced G2/M arrest and aberrant mitosis characterized by abnormal bipolar mitotic spindles, condensed chromosomes, lagging DNA and chromosome bridges. In addition, over-expression of miR-509-3-5p markedly blocked A549 cell proliferation and sensitized the cells to CIS and ADR treatment. Taken together, miR-509-3-5p is a feasible suppressor for cancer by targeting PLK1. Our data may provide aid in potential design of combined chemotherapy and in our better understanding of the roles of microRNAs in response to DNA damage.

E2F1 regulates p53R2 gene expression in p53-deficient cells.

The p53R2 gene encoding a small subunit of the ribonucleotide reductase has been identified as a p53-inducible gene. Although this gene is discovered as a target for p53 family proteins, the mechanism underlying p53R2 induction by DNA damage in p53-defiencient cells remains to be elucidated. In this study, we demonstrate that transcription factor E2F1 regulates the p53R2 gene expression in p53-deficient cells. We found that p53R2 was a target for E2F1 in DNA damage response (DDR), because ectopic expression of E2F1 in HCT116-p53(-/-) cells resulted in the increase of p53R2 mRNA and protein expression, and silencing E2F1 diminished its basic expression. Combination of luciferase reporter assay with overexpression or knockdown of E2F1 revealed that E2F1 directly activates the p53R2 gene. Chromatin immunoprecipitation (ChIP) assay showed E2F1 directly bound to the site (TTTGGCGG) at position -684 to -677 of the promoter under E2F1 overexpression or adriamycin (ADR) exposure. Moreover, silencing p53R2 could enhance apoptotic cell death in both HCT116-p53(-/-) and HCT116-p53(+/+) compared to ADR exposure, indicating that p53R2 may protect cancer cell from ADR-induced apoptosis. Together, we have identified a new role of E2F1 in the regulation of p53R2 expression in DDR, and silencing p53R2 may sensitize cancer cells to ADR-induced apoptosis. Our data support the notion that p53R2 is a potential target for cancer therapy. The involvement of E2F1-dependent p53R2 activation in DDR will provide further insight into the induction of p53R2 in p53-deficient cells. These data also give us a deeper understanding of E2F1 role in DDR.

E2F1-regulated DROSHA promotes miR-630 biosynthesis in cisplatin-exposed cancer cells.

DNA damage may regulate microRNA (miRNA) biosynthesis at the levels of miRNA transcription, processing and maturation. Although involvement of E2F1 in the regulation of miRNA gene activation in response to DNA damage has been documented, little is known about the role of E2F1 in miRNA processing. In this study we demonstrate that E2F1 enhances miR-630 biosynthesis under cisplatin (CIS) exposure through promoting DROSHA-mediated pri-miR-630 processing. Northern blot and RT-qPCR revealed that CIS exposure caused not only an increase in pri-miR-630 but also much more increase in pre-miR-630 and mature miR-630. The increases in pri-miR-630 and pre-miR-630 expression in unmatched proportion indicated that primary transcript processing was involved in CIS-stimulated miR-630 biosynthesis. Furthermore, combination of reporter enzyme assay with mutation and over-expression of E2F1 showed that induction of DROSHA promoted miR-630 expression, in which CIS-induced E2F1 activated DROSHA gene expression by recognizing and binding two E2F1 sites at the positions -214/-207 and -167/-160 of the DROSHA promoter. The increased binding of E2F1 to the DROSHA promoter in CIS-exposed cells was further evidenced by chromatin immunoprecipitation assay. Together, E2F1-regulated DROSHA promotes pri-miR-630 processing, thereby, contributes to CIS-stimulated miR-630 expression. The involvement of E2F1-dependent DROSHA activation in pri-miRNA processing under DNA damage stress will provide further insight into the regulation of miRNA biosynthesis. These data also give us a deeper understanding of E2F1 role in response to DNA damage.

p53 Suppresses E2F1-dependent PLK1 expression upon DNA damage by forming p53-E2F1-DNA complex.

E2F1 is implicated in transcriptional activation of polo-like kinase-1 (PLK1), but yet the mechanism is not fully understood. PLK1 suppression plays an important checkpoint role in response to DNA damage. Suppression of the PLK1 gene by binding of p53 to upstream p53RE2 element in the promoter has been recently revealed. Here we report another mechanism, in which p53 interacts with E2F1 to form p53-E2F1-DNA complex repressing E2F1-dependent PLK1 expression. PLK1 was downregulated in cisplatin exposed HCT116p53(+/+) but not HCT116p53(-/-) cells, indicating p53-suppressed PLK1 upon DNA damage. Co-transfection and reporter enzyme assays revealed that p53 suppressed but E2F1 promoted PLK1 gene activation. 5'-Deletion and substitution mutations showed multiple positive cis-elements residing in the PLK1 promoter, of which at least two E2F1 sites at positions -75/-68 and -40/-32 were required for the full activity of the promoter. Combination of 5'-deletion and substitution mutations with over-expression of p53 showed that suppression of the PLK1 gene by p53 was E2F1-dependent: mutation of the E2F1 site at position -75/-68 partially abrogated suppression activity of p53; mutation of E2F1 site at position -40/-32 released from p53 suppression of PLK1 gene completely. Co-immunoprecipitation and electrophoretic mobility shift assay showed that DNA damage promoted p53-E2F1 interaction, thereby creating a p53-E2F1 complex assembly on the PLK1 promoter in vitro. The in vivo formation of p53-E2F1-PLK1 promoter complex upon DNA damage was further evidenced by chromatin immunoprecipitation (ChIP) and re-ChIP. In addition, we showed that suppression of PLK1 by p53 promoted apoptosis. Our data suggest that p53 may interact with E2F1 to form p53-E2F1-DNA complex suppressing E2F1-dependent PLK1 expression. The model of p53 action on E2F1-activated PLK1 gene may explain at least partly how p53 as a suppressor regulates the downstream effects of E2F1 in cellular stresses including DNA damage stress.

E2F1-mediated DNA damage is implicated in 8-Cl-adenosine-induced chromosome missegregation and apoptosis in human lung cancer H1299 cells.

Although E2F1-mediated DNA double-stranded breaks (DSBs) and tetraploid have been extensively studied, the role of E2F1 in mitotic catastrophe is still unknown. We have previously shown that 8-chloro-adenosine (8-Cl-Ado) induces DNA DSBs and aberrant mitosis in human lung cancer cells, followed by delayed apoptosis. Here, we demonstrate that E2F1-mediated DNA damage is implicated in 8-Cl-Ado-induced chromosome missegregation and apoptosis in lung cancer H1299 cells. We showed that E2F1 was accumulated upon 8-Cl-Ado-induced DNA DSBs. Induction of E2F1 by 8-Cl-Ado caused DNA damage in cycling cells including M cells. In contrast, silencing of E2F1 expression decreased 8-Cl-Ado-induced DNA DSBs, particularly eliminated E2F1-mediated mitotic DNA damage. Over-expression of E2F1 and/or 8-Cl-Ado exposure resulted in aberrant mitotic spindles and chromosome segregation errors. Furthermore, over-expression of E2F1 expression enhanced 8-Cl-Ado-induced apoptosis. Together, our data indicate that E2F1-mediated DNA damage, in particular mitotic DNA damage, is an important fraction of 8-Cl-Ado-induced DNA damage, which is implicated in 8-Cl-Ado-induced mitotic catastrophe and delayed apoptosis. Induction of E2F1 by 8-Cl-Ado may contribute at least partly to the drug-inhibited proliferation of cancer cells.

E2F1 enhances 8-chloro-adenosine-induced G2/M arrest and apoptosis in A549 and H1299 lung cancer cells.

The E2F1 transcription factor is a well known regulator of cell proliferation and apoptosis, but its role in response to DNA damage is less clear. 8-Chloro-adenosine (8-Cl-Ado), a nucleoside analog, can inhibit proliferation in a variety of human tumor cells. However, it is still elusive how the agent acts on tumors. Here we show that A549 and H1299 cells formed DNA double-strand breaks after 8-Cl-Ado exposure, accompanied by E2F1 upregulation at protein level. Overexpressed wild-type (E2F1-wt) colocalized with double-strand break marker γ-H2AX and promoted G2/M arrest in 8-Cl-Ado-exposed A549 and H1299, while expressed S31A mutant of E2F1 (E2F1-mu) significantly reduced ability to accumulate at sites of DNA damage and G2/M arrest, suggesting that E2F1 is required for activating G2/M checkpoint pathway upon DNA damage. Transfection of either E2F1-wt or E2F1-mu plasmid promoted apoptosis in 8-Cl-Ado-exposed cells, indicating that 8-Cl-Ado may induce apoptosis in E2F1-dependent and E2F1-independent ways. These findings demonstrate that E2F1 plays a crucial role in 8-Cl-Ado-induced G2/M arrest but is dispensable for 8-Cl-Ado-induced apoptosis. These data also suggest that the mechanism of 8-Cl-Ado action is complicated.

p14ARF interacts with E2F factors to form p14ARF-E2F/partner-DNA complexes repressing E2F-dependent transcription.

Primarily, E2F factors such as E2F1, -2, and -3 stimulate cell-cycle progression, while ARF tumor suppressor mediates growth suppression. The ARF gene can be induced by oncogenic signal through activating E2F-dependent transcription. In turn, ARF may target E2F for its degradation via a p53-dependent mechanism. However, it remains unclear how the cell keeps the balance between the functional opposites of E2F and ARF. In this study, we demonstrate that p14ARF interacts with E2F1-3 factors to directly repress their transcriptional activities through forming p14ARF-E2F/partner-DNA super complexes, regardless of E2F protein degradation. The inhibition of E2F transcriptional activities by p14ARF in this manner occurs commonly in a variety of cell types, including p53-deficient and p53-wild type cells. Thus, E2F-mediated activation of the ARF gene and ARF-mediated functional inhibition of E2F compose a feedback loop, by which the two opposites act in concert to regulate cell proliferation and apoptosis, depending on the cellular context and the environment.

Calcium signal-initiated early activation of NF-kappaB in neurons is a neuroprotective event in response to kainic acid-induced excitotoxicity.

We demonstrate that activation of nuclear factor kappaB (NF-kappaB) in neurons is neuroprotective in response to kainic acid (KA)-induced excitotoxicity. Combination of Western blotting, immunocytochemistry, and electrophoresis mobility shift assay showed that KA exposure induced a fast but transient nuclear translocation of the NF-kappaB p65 subunit and increased DNA-binding activity of NF-kappaB in primary cultured cortical neurons. The transient NF-kappaB activity was associated with upregulation of antiapoptotic Bcl-xL and XIAP gene products revealed by real-time PCR. Knockdown of p65 decreased neuronal viability and antiapoptotic gene expression. In addition, we showed that KA-stimulated DNA-binding activity of NF-kappaB was associated with reactive oxygen species and calcium signals, using AMPA/KA receptor antagonist, calcium chelator, and antioxidant. These results suggest that the fast and transient activation of NF-kappaB initiated by calcium signals is one of the important proximal events in response to KA-induced excitotoxicity, which has neuroprotective effect against KA-induced apoptosis.

MiR-509-3-5p-NONHSAT112228.2 Axis Regulates p21 and Suppresses Proliferation and Migration of Lung Cancer Cells.

BACKGROUND: Although the involvement of individual microRNA and lncRNA in the regulation of p21 expression has largely been evidenced, less is known about the roles of functional interactions between miRNAs and lncRNAs in p21 expression. Our previous work demonstrated that miR-509- 3-5p could block cancer cell growth. METHODS: To gain an insight into the role of miR-509-3-5p in the regulation of p21 expression, we performed in silico prediction and showed that miR-509-3-5p might target the NONHSAT112228.2, a sense-overlapping lncRNA transcribed by a non-code gene overlapping with p21 gene. Mutation and luciferase report analysis suggested that miR-509-3-5p could target NONHSAT112228.2, thereby blocking its expression. Consistently, NONHSAT112228.2 expression was inversely correlated with both miR-509-3-5p and p21 expression in cancer cells. Ectopic expression of miR-509-3-5p and knockdown of NONHSAT112228.2 both promoted proliferation and migration of cancer cells. RESULTS: Interestingly, high-expression of NONHSAT112228.2 accompanied by low-expression of p21 was observed in lung cancer tissues and associated with lower overall survival. CONCLUSION: Taken together, our study found a new regulatory pathway of p21, in which MiR-509-3-5p functionally interacts with NONHSAT112228.2 to release p21 expression. MiR-509-3-5p- NONHSAT112228.2 regulatory axis can inhibit the proliferation and migration of lung cancer cells.

A Systematic Analysis of Dysregulated Long Non-Coding RNAs/microRNAs/mRNAs in Lung Squamous Cell Carcinoma.

BACKGROUND: Lung squamous cell carcinoma (LUSC) accounts up for approximately 30% of all lung cancers with a high mortality. The study was aimed at finding genes critical in the diagnosis and prognosis of LUSC. MATERIALS AND METHODS: The differentially expressed (DE) genes (DEGs) and DE lncRNAs (DELs) from 501 LUSC and 49 normal lung tissues, and DE miRNAs (DEMs) from 478 LUSC and 45 normal lung tissues were respectively obtained via the TCGA database. Gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, and co-expression network analyses were performed. Survival analysis and receiver operating characteristic curve of hub mRNAs were also analyzed. Competitive endogenous RNA networks of lncRNAs, miRNAs and mRNAs were constructed. RESULTS: A total of 5747 DEGs, 378 DEMs and 3141 DELs in LUSC were identified in LUSC. The DEGs including AUARK, CDK1, KIF11 and EXO1 were proven to be significant metastatic indicators in LUSC, and 2 DEGs were significantly associated with the survival in LUSC patients. Some genes might have connections with many other gene nodes through a co-expression network. Four lncRNAs, 2 mRNAs and 2 miRNAs were identified as the candidates for the competitive miRNA-mRNA-lncRNA network and might serve as prognostic markers in LUSC. CONCLUSIONS: We identified the differentially expressed lncRNAs, miRNAs and mRNAs in LUSC, providing further insights into the molecular mechanism of LUSC tumorigenesis and the potential prognostic biomarkers or therapeutic targets for LUSC.

8-Chloro-adenosine-induced E2F1 promotes p14ARF gene activation in H1299 cells through displacing Sp1 from multiple overlapping E2F1/Sp1 sites.

The regulation of p14ARF gene by E2F transcription factor, which differs from that of classical E2F targets, has recently been attributed to a variant E2F-response element. However, promoter assays suggest multiple elements present in the p14ARF promoter and argue against the idea that the ARF promoter has a unique ability to distinguish between aberrant and physiological levels of E2F1. Therefore, the functional characterization of the promoter still needs to be done. We demonstrate that at least two overlapping E2F1/Sp1 binding sites are present in the p14ARF promoter, and E2F1 activates the promoter through displacing constitutive Sp1 from the overlapping sites. We found that 8-chloro-adenosine (a metabolite of 8-Cl-cAMP) exposure induced the p14ARF gene in human lung cancer H1299 cells, followed by increased expression of E2F1 and constitutive expression of Sp1. The combination of cotransfection and electrophoretic mobility shift assay (EMSA) indicated that constitutive binding of Sp1 to the overlapping sites contributed to a constitutive expression of the ARF gene in unexposed H1299, whereas displacing Sp1 from the overlapping sites by E2F1 promoted the gene activation after exposure. EMSA and chromatin immunoprecipitation revealed increased association of E2F1 with the overlapping sites in the active promoter in 8-Cl-Ado-exposed cells. Together, these data suggest that the overlapping E2F1/Sp1 site, being present in multiple copies in the p14ARF promoter, may serve as the targets for both E2F1 and Sp1, thereby playing a crucial role in response to some oncogenic signals and stimulators, which activate the ARF gene through inducing E2F in the cell.

Induction of p14ARF by E2F1 contributes to 8-chloro-adenosine-induced apoptosis in human lung cancer H1299 cells.

BACKGROUND: 8-Chloro-adenosine (8-Cl-Ado) inhibits tumor cell proliferation by inducing cell-cycle arrest and apoptosis. We speculate that upregulation of p14ARF by E2F1 might contribute to 8-Cl-Ado-induced late apoptosis. METHODS: Hoechst staining, cell proliferation and TUNEL assays, real-time quantitative PCR, Western blotting, chromatin immunoprecipitation and RNA interference were employed in investigating the role of induction of p14ARF by E2F1 in 8-Cl-Ado-induced apoptosis in human lung cancer H1299 cells. RESULTS: Exposure of H1299 to 8-Cl-Ado led to apoptosis after long exposure (48 h), revealed by the appearance of nucleus fragmentation and apoptotic bodies and the activation of procaspase-3 pathway. Western blotting and RT-PCR showed that the upregulation of p14ARF was in parallel with E2F1 expression during exposure. Furthermore, induction of p14ARF was attributed to increased E2F1 expression, evidenced by E2F1 transfection and chromatin immunoprecipitation/real-time quantitative PCR. Knockdown of p14ARF expression in H1299 decreased TUNEL-positive cell numbers and relatively increased survival cell numbers during 8-Cl-Ado exposure, indicating insensitivity of p14ARF-knocked down cells to 8-Cl-Ado. CONCLUSIONS: Induction of p14ARF by E2F1 contributes to 8-Cl-Ado-induced late apoptosis.

[Immunohistochemical localization of enamelin in developing rat tooth germ].

OBJECTIVE: To observe the immunohistochemical localization of enamelin in enamel formationand mineralization. METHODS: Tissue sections of the first mandibular molar tooth germ from 1, 3, 7, 10, 14 days rats after birth were prepared, expression of the enamelin protein was identified by immunohistochemical technique. RESULTS: Enamelin was found in the cytoplasm of ameloblasts in 1-10 days old rat postnatal first mandibular molar tooth germs. Enamelin appeared weakly in the tooth germs of 1 day rats. From 3 to 10 days, enamelin localized both in the cytoplasm of ameloblasts and the uncalcified enamel from the dentino-enamel junction to surfaces of the tooth. Enamelin protein was negative in the tooth germs of 14 days rats postnatally. CONCLUSION: Enamelin protein is synthesised and secreted by ameloblasts, specially localized in enamel from DEJ to surfaces of the tooth, suggesting that enamelin has important roles in enamel formation.

8-Chloro-adenosine inhibits growth at least partly by interfering with actin polymerization in cultured human lung cancer cells.

A key feature of actin is its ability to bind and hydrolyze ATP. 8-Chloro-adenosine (8-Cl-Ado), which can be phosphorylated to the moiety of 8-Cl-ATP in living cells, inhibits tumor cell proliferation. Therefore we tested the hypothesis that 8-Cl-Ado can interfere with the dynamic state of actin polymerization. We found that 8-Cl-Ado inhibited the growth of human lung cancer cell line A549 and H1299 in culture, and arrested the target cells in G2/M phase evidenced by fluorescence-activated cell sorting (FACS). Immunocytochemistry showed that the normal organization of microfilaments was disrupted in 8-Cl-Ado-exposed cells, which is accompanied by the decrease of cell size and the alteration of cell shape, and by aberrant mitosis and apoptosis in targeted cells. Furthermore, in vitro light scattering assays revealed that 8-Cl-ATP could directly inhibit the transition of G-actin to F-actin. DNase I inhibition assays showed that the G/F-actin ratio, a surrogate marker of actin polymerization status in living cells, was significantly increased in 8-Cl-Ado-exposed A549 and H1299 cells, compared to the G/F-actin ratio in unexposed cells. Taken together, these results indicate that 8-Cl-Ado exposure can alter the dynamic properties of actin polymerization, disrupt the dynamic instability or the rearrangement ability of actin filaments. Therefore, our data suggest that 8-Cl-Ado may exert its cytotoxicity at least partly by interfering with the dynamic instability of microfilaments, which may correlate with its inhibitory effects on cell proliferation and cell death.

Kainate exposure suppresses activation of GluR2 subunit promoter in primary cultured cerebral cortical neurons through induction of RE1-silencing transcription factor.

The AMPA receptor subunit GluR2 is downregulated in neurons following a wide range of neurological insults. Here we report that suppression of GluR2 gene promoter activity is associated with kainate (KA)-induced downregulation of GluR2 subunit levels in primary cultured cortical neurons. RT-PCR and Northern blotting showed a significant decrease in GluR2 mRNA in cultured neurons after KA exposure. Transfection of cultured neurons with an expression vector pGL3-GluR2(-298/+283), where the reporter gene firefly luciferase was driven by the GluR2 promoter, revealed that KA exposure suppressed the transcriptional activation of the GluR2 promoter. Furthermore, the expression of the RE1-silencing transcription factor (REST) was increased in KA-exposed cortical neurons; enhanced binding of REST to RE1-like silencer element in the proximal promoter of the GluR2 subunit gene was evidenced by electrophoresis mobility shift assay. Chromatin immunoprecipitation showed that suppressed activity of the GluR2 promoter in cultured neurons after KA exposure was related to deacetylation of histone H4. These results indicate that REST as a crucial factor binds to RE1-like silencer element in the GluR2 promoter, suppressing transcription of the GluR2 subunit gene during KA exposure. Our data suggest that transcriptional suppression of the GluR2 subunit gene may contribute at least in part to downregulation of GluR2 subunit protein in neurons during KA exposure. Because our experiments showed a reduction of glutamate release in KA-exposed cortical neurons, REST may play a latent role in delayed neuronal death or in seizure-induced tolerance.

[Research Progress on Expression Regulation, Function and Clinical Significance of CASP8AP2 Gene].

We systematically reviewed the results of the studies on expression regulation, biological functions, and clinical prognostic significance of CASP8AP2 gene. At present, the studies showed that the expression of CASP8AP2 gene was regulated by Homeobox proteins and DNA methylation, and could be silenced by miRNA-210. This protein was involved in apoptosis mediated by FAS and TNFα, NF-κB activation mediated by TNFα, regulation of gene expression induced by glucocorticoid and mineralocorticoid receptor, comprising Cajal body and histone locus body, transcription of replication-dependent histone, 3' end processing of histone, regulation of S phase progression, in addition to functioning as coactivator of transcription factors c-Myb and p73 to activating many genes' expression. On the other hand, low expression of CASP8AP2 gene was associated with relapse in childhood ALL. The deletion of this gene was related to the poor prognosis of children with T-ALL and T lymphoblastic lymphoma. Furthermore, 3 SNPs in this gene were possibly correlated with genesis of diffuse large B cell lymphoma and childhood leukemia. In conclusions, CASP8AP2 was a multifunctional protein. It could function to regulate cell proliferation, apoptosis, and gene expression. In childhood hematological malignancies, CASP8AP2 was a promising molecular marker with prognostic significance. Some SNPs were possibly correlated with leukemo- and lymphomogenesis.