Thymus and lung mucosa-associated lymphoid tissue lymphoma with adenocarcinoma of the lung: a case report and literature review.

BACKGROUND: Mucosa-associated lymphoid tissue (MALT) lymphoma is a common, low-grade, malignant B-cell lymphoma. However, simultaneous MALT lymphoma in the thymus and lung is extremely rare, and concomitant adenocarcinoma of the lung is even rarer. Herein, we report a rare case of a collision tumor in which MALT lymphoma was found in both the thymus and lung with Sjögren's syndrome (SS) and adenocarcinoma in the lung. CASE PRESENTATION: A physical examination of a 32-year-old woman revealed an anterior superior mediastinal space-occupying lesion, and chest computed tomography (CT) indicated a nodular ground-glass opacity and irregular mixed-density focus in the right lung. All lung cancer-related tumor biomarkers were within normal ranges. The thymus and part of the lung tissue were surgically resected. The histopathology and molecular examinations confirmed MALT lymphoma of the thymus and lung with lung adenocarcinoma. SS was also diagnosed. No special postoperative treatment was performed for the MALT lymphoma, and the patient underwent immunosuppressive therapy for SS after 4 months of follow-up observation. CONCLUSIONS: MALT lymphoma of the thymus and lung tissues has no specific presentation on imaging and is difficult to differentiate from common malignant tumors, and the definite diagnoses of these tumors are highly dependent on histopathological examination in combination with molecular testing and cytogenetics. SS may be an important potential condition for the occurrence of MALT lymphoma in the thymus and lung. Additional similar cases are needed to clarify the biological pathways and potential molecular mechanisms of rare lymphomas and collision tumors.

A multicentre trial of intensive immunosuppressive therapy combined with umbilical cord blood for the treatment of severe aplastic anaemia.

Immunosuppressive therapy (IST) is an effective treatment regimen for severe aplastic anaemia (SAA) patients without HLA-identical donors. This study further compared the outcomes between IST and IIST-UCB in SAA on the basis of research shown that IST combined with umbilical cord blood infusion (IIST-UCB) treated effectively. A total of 123 patients from 11 hospitals in China were enrolled. Sixty-nine patients in IIST-UCB group were treated with ATG + CsA + CTX combined with cord blood, while 54 patients in IST group with ATG + CsA. The overall remission rates (ORRs), complete remission (CR) rates and partial response (PR) rates of IIST-UCB group and IST group at 3 months were 69.67% vs 51.85% (P = .045), 21.74% vs 3.7% (P = .004) and 47.83% vs 48.15% (P = .972), respectively. After 6 months of treatment, they were 76.81% vs 57.41% (P = .022), 37.68% vs 11.11% (P = .001) and 39.13% vs 46.30% (P = .425), respectively. After 1 year of treatment, they were 85.51% vs 61.11% (P = .002), 59.42% vs 25.93% (P = .000) and 26.09% vs 35.19% (P = .275), respectively. The ORRs and CR rates of IIST-UCB group were both significantly higher than IST group after 3 months, 6 months and 1 year of treatment. The neutrophil granulocyte, platelet and haemoglobin recovery times of IIST-UCB group were significantly shorter than IST group. Compared with standard IST, IIST-UCB as an effective therapy for SAA patients without HLA-identical donors accelerated the haematopoietic reconstitution, resulting in higher early CR rates.

Identification of Hub Genes and Pathways Associated with CAR-T Cell-Mediated Neurotoxicity in DLBCL.

BACKGROUND: Severe neurotoxicity after chimeric antigen receptor T cell (CAR-T) therapy can be a crucial lifethreatening event in diffuse large B-cell lymphoma (DLBCL), and management of those toxicities is still a serious clinical challenge. The underlying mechanisms of CAR-T cell-mediated neurotoxicity remain poorly elucidated because very few studies examine the intact tumor microenvironment before CAR-T cell infusion. Herein, we pur-posed to identify differentially expressed genes (DEGs) related to CAR-T cell-mediated neurotoxicity in the DLBCL microenvironment before CAR-T cell infusion and reveal their potential mechanisms. METHODS: The mRNA expression profile data of GSE153438 were obtained from the GEO database. The GSE153438 dataset includes 26 samples with non-severe neurotoxicity (grade 0 - 2) and 10 samples with severe neurotoxicity (grade 3 or higher). Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) patway enrichment assessment was carried out. We screened the hub gene by protein-protein interaction (PPI) network analysis and Cytoscape software. Gene set enrichment analysis (GSEA) was also analyzed with the GSEA software. Moreover, the predictive value of the hub gene for severe neurotoxicity was evaluated via receiver operating characteristic (ROC) curve analysis. RESULTS: We identified a total of 25 up-regulated DEGs and 26 downregulated DEGs associated with CAR-T cell-mediated neurotoxicity in the DLBCL microenvironment before CAR-T cell infusion. Results of GO analysis showed that DEGs were mainly enriched in T cell activation, leukocyte cell-cell adhesion, and positive regulation of cell adhesion. The KEGG analysis revealed that DEGs were significantly enriched in T cell receptor signaling pathway, cell adhesion molecules, and Epstein-Barr virus infection. GSEA revealed that the glycolysis pathway was significantly associated with severe neurotoxicity. The top centrality hub gene GZMB was identified from the PPI network. ROC curve analysis showed that GZMB had a potential predictive value for severe neurotoxicity. CONCLUSIONS: In DLBCL microenvironment before CAR-T cell infusion, we identified T cell activation and glycolysis pathways significantly associated with CAR-T cell-mediated severe neurotoxicity. GZMB might be used as a predictive and therapeutic molecular marker for neurotoxicity. The study suggested that the tumor microenviron-ment before CAR-T cell infusion plays an essential role in the early prediction of neurotoxicity.

Arsenic disulfide promoted the demethylation of PTPL1 in diffuse large B cell lymphoma cells.

Background: Promoter hypermethylation of the tumor suppressor gene is one of the well-studied causes of cancer development. The drugs that reverse the process by driving demethylation could be a candidate for anticancer therapy. This study was designed to investigate the effects of arsenic disulfide on PTPL1 methylation in diffuse large B cell lymphoma (DLBCL). Methods: We knocked down the expression of PTPL1 in two DLBCL cell lines (i.e., DB and SU-DHL-4 cells) using siRNA. Then the DLBCL proliferation was determined in the presence of PTPL1 knockdown. The methylation of PTPL1 in DLBCL cells was analyzed by methylation specific PCR (MSPCR). The effect of arsenic disulfide on the PTPL1 methylation was determined in DLBCL cell lines in the presence of different concentrations of arsenic disulfide (5 µM, 10 µM and 20 µM), respectively. To investigate the potential mechanism on the arsenic disulfide-mediated methylation, the mRNA expression of DNMT1, DNMT3B and MBD2 was determined. Results: PTPL1 functioned as a tumor suppressor gene in DLBCL cells, which was featured by the fact that PTPL1 knockdown promoted the proliferation of DLBCL cells. PTPL1 was found hypermethylated in DLBCL cells. Arsenic disulfide promoted the PTPL1 demethylation in a dose-dependent manner, which was related to the inhibition of DNMTs and the increase of MBD2. Conclusion: Experimental evidence shows that PTPL1 functions as a tumor suppressor gene in DLBCL progression. PTPL1 hyper-methylation could be reversed by arsenic disulfide in a dose-dependent manner.

A fucoidan plant drink reduces Helicobacter pylori load in the stomach: a real-world study.

Background: Helicobacter pylori (Hp) infection is highly prevalent globally and is predominantly managed by antibiotics. Recently, the anti-adhesive, antioxidant, antitoxin, immunomodulatory, anti-coagulant, and anti-infective activities of fucoidan, a polysaccharide extracted from brown seaweeds, have been widely studied, and the results showed promise. Fucoidan has the potential to be utilized in Hp eradication therapy. Our present clinical study was designed to evaluate the efficiency of Lewuyou®, a fucoidan plant drink (FPD) in eradicating Hp in humans. Methods: This multi-center, clinical study was conducted between October 2020 and July 2021. Hp infection was confirmed by urea breath test (UBT). A total of 122 patients with confirmed Hp infection were enrolled; after exclusion of incomplete data, 85 eligible patients (37 males and 48 females aged 20-81 years) were included in the final analysis. FPD (50 mL per vial) was orally administered twice daily for a 4-week cycle, and 41 patients completed an 8-week cycle. Results: No adverse event (AE) was reported in all 122 participants who had consumed FPD. The Hp eradication rate and clearance rate were 77.6% (66/85) and 20.0% (17/85), respectively, after 4 weeks of FPD consumption and 80.5% (33/41) and 26.8 (11/41) , respectively, after 8 weeks of consumption. Conclusions: The 4- and 8-week protocols of FPD consumption were safe and effective at reducing Hp load on the gastric mucosa, with Hp eradicated in the majority of participants.

MiR-665 suppresses the progression of diffuse large B cell lymphoma (DLBCL) through targeting LIM and SH3 protein 1 (LASP1).

Diffuse large B cell lymphoma (DLBCL), the most common type of non-Hodgkin lymphoma worldwide, is aggressive and highly heterogeneous. MiR-665 was found to be lowly expressed in serum exosomes of DLBCL patients and in DLBCL cell lines, but its function in DLBCL progression remains unclear. In this study, miR-665 was overexpressed in SU-DHL-4 cells via miR-665 mimics and knocked down in FARAGE cells via miR-665 inhibitor. Knockdown of miR-665 promoted DLBCL cell proliferation and invasion and decreased cell apoptosis, whereas miR-665 overexpression showed opposite effects on DLBCL cell malignant behaviors. Luciferase reporter assay confirmed LIM and SH3 protein 1 (LASP1) and MYC as target genes of miR-665. Moreover, the expression of LASP1 was negatively correlated with that of miR-665 in LDLBCL cells. LASP1 has tumor-promoting property and its inhibition abolished the effect of miR-665 knockdown on DLBCL cell proliferation, invasion, and apoptosis. SU-DHL-4 cells were inoculated into the flank of nude mice, followed by orthotopic injection with miR-665 agomir. MiR-665 overexpression restricted tumor growth in vivo. Thus, we demonstrates that miR-665 suppresses DLBCL cell malignant behaviors by inhibiting cell proliferation and invasion and inducing apoptosis via targeting LASP1 and MYC, suggesting the importance of miR-665 in DLBCL progression.

[The Effect of γ-secretase Inhibitor Combined with BMSC on the aGVHD in Mice Model].

OBJECTIVE: To establish the aGVHD mouse model，and investigate the regulatory effect and its mechanism of low-dose GSI combined with BMSC on aGVHD mice. METHODS: C57BL/6 (H-2b) and BALB/c (H-2d) were selected as donor and recipient of allogeneic transplantation to establish the aGVHD mouse model. BALB/c mice were randomly divided into 6 groups, which were the bone marrow cell infusion after irradiation (BM) group; the bone marrow cells + spleen cells after irradiation (BM+SC) group; the bone marrow cells + spleen cells + DMSO (BM+SC+DMSO) (transplant control) group; bone marrow cells + splenocytes +GSI after irradiation (BM+SC+GSI) group; bone marrow cells + spleen cells + bone marrow mesenchymal stromal infusion after irradiation cell (BM+SC+BMSC) group; bone marrow cells + spleen cells + bone marrow mesenchymal stromal cells +GSI infused after irradiation (BM+SC+BMSC+GSI) group. The mice in the two groups containing GSI were intraperitoneally injected with GSI at 5 µmol/kg on day 1, 2, and 3 after transplantation with DMSO as a control. The general conditions, survival time and hematopoietic recovery of mice were observed, cytokines were detected by ELISA, and histopathological changes were detected by immunohistochemistry. The effects of low-dose GSI combined with BMSC on hematopoietic reconstruction and aGVHD development after allo-BMT were investigated. RESULTS: The survival rate of the mice in BM+SC+BMSC+GSI combination group was 80% during the observation period, which was significantly higher than that in the other groups; the incidence of aGVHD was reduced in the BMSC GSI or their combination groups after 21 days of transplantation. GSI could partly promote the recovery of leukocytes, and show no significant delayed effect on the recovery platelets. Moreover, the level of Th1 cytokines (IFN-γ) in BM+SC+BMSC+GSI combined group was lower than that in BM+SC+GSI group (P<0.01), the level of Th2 cytokines (IL-4) in the combination group was higher than that in BM+SC+GSI group (P<0.01), also the level of IL-17 was significantly lower than that in the corresponding control group (P<0.001). CONCLUSION: Low dose GSI combined with BMSC can promote hematopoietic reconstruction and regulate cytokines secretion including IFN-γ, IL-4 and IL-17. GSI combined with BMSC achieve the goal of synergistically inhibiting the occurrence and progression of aGVHD.

PAK1 Mediates Bone Marrow Stromal Cell-Induced Drug Resistance in Acute Myeloid Leukemia via ERK1/2 Signaling Pathway.

BACKGROUND: Chemoresistance is emerging as a major barrier to successful treatment in acute myeloid leukemia (AML), and bone marrow stromal cells (BMSCs) protect leukemia cells from chemotherapy eventually leading to recurrence. This study was designed to investigate the role of p21-activated kinase 1 (PAK1) in AML progression and chemosensitivity, highlighting the mechanism of stroma-mediated chemoresistance. METHODS: The GEPIA and TCGA datasets were used to analyze the relationship between PAK1 mRNA expression and various clinical parameters of AML patients. Cell proliferation and apoptosis were examined to evaluate the role of PAK1 on chemosensitivity in AML by silencing PAK1 with shRNA or small molecular inhibitor. Human BMSC (HS-5) was utilized to mimic the leukemia bone marrow microenvironment (BMM) in vitro, and co-culture model was established to investigate the role of PAK1 in BMSC-mediated drug resistance. RESULTS: p21-activated kinase 1 high expression was shown to be associated with shorter overall survival in AML patients. The silence of PAK1 could repress cell proliferation, promote apoptosis, and enhance the sensitivity of AML cells to chemotherapeutic agents. More importantly, BMSCs induced PAK1 up-regulation in AML cells, subsequently activating the ERK1/2 signaling pathway. The effect of BMSC-mediated apoptotic-resistance could be partly reversed by knock down of PAK1. CONCLUSION: p21-activated kinase 1 is a potential prognostic predictor for AML patients. PAK1 may play a pivotal role in mediating BMM-induced drug resistance, representing a novel therapeutic target in AML.

[Effects of Arsenic Disulfide Combined with Itraconazole on Proli- feration and Apoptosis and Hedgehog Pathway of Diffuse Large B-Cell Lymphoma Cells].

OBJECTIVE: To investigate the effect of arsenic disulfide (AS2S2) combined with itraconazole on the proliferation, apoptosis and hedgehog pathway of diffuse large B-cell lymphoma (DLBCL) cells. METHODS: The human DLBCL cell OCI-LY3 was treated with different concentrations of AS2S2 and itraconazole. Cell proliferation inhibition was detected by CCK-8, cell apoptosis rate was determined by flow cytometry. The expression levels of BCL-2, BAX, SMO and GLi1 were detected by Western blot. RESULTS: The DLBCL cell viability was decreased significantly at 24, 48 or 72 h as cultured with itraconazole. Along with the increasing of itraconazole concentration, the DLBCL cell viability was significantly reduced as compared with that in control group, and the results showed statistically significant(r=-0.690，r=-0.639, r=-0.833, r=-0.808, r=-0.578). The inhibitory and apoptosis rates of the cells were significantly increased as compared with those of the single drug-treated group after treated by the combination of itraconazole and AS2S2(P<0.05). The protein levels of SMO and Glil were significantly down-regulated after treated by arsenic disulfide and itraconazole alone(P<0.01). The protein expression levels of SMO and Glil was down-regulated in the combined-treatment group(P<0.01). CONCLUSION: Itraconazole can inhibit proliferation of DLBCL cells in a concentration-and time-dependent manner. In addition, the combination of AS2S2 and itraconazole show a synergistic effects, which may be related with the down-regulated protein expression of SMO and Glil of Hedgehog signaling pathway.

Identification of key gene modules and hub genes of human mantle cell lymphoma by coexpression network analysis.

PURPOSE: Mantle cell lymphoma (MCL) is a rare and aggressive subtype of non-Hodgkin lymphoma that is incurable with standard therapies. The use of gene expression analysis has been of interest, recently, to detect biomarkers for cancer. There is a great need for systemic coexpression network analysis of MCL and this study aims to establish a gene coexpression network to forecast key genes related to the pathogenesis and prognosis of MCL. METHODS: The microarray dataset GSE93291 was downloaded from the Gene Expression Omnibus database. We systematically identified coexpression modules using the weighted gene coexpression network analysis method (WGCNA). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) functional enrichment analysis were performed on the modules deemed important. The protein-protein interaction networks were constructed and visualized using Cytoscape software on the basis of the STRING website; the hub genes in the top weighted network were identified. Survival data were analyzed using the Kaplan-Meier method and were compared using the log-rank test. RESULTS: Seven coexpression modules consisting of different genes were applied to 5,000 genes in the 121 human MCL samples using WGCNA software. GO and KEGG enrichment analysis identified the blue module as one of the most important modules; the most critical pathways identified were the ribosome, oxidative phosphorylation and proteasome pathways. The hub genes in the top weighted network were regarded as real hub genes (IL2RB, CD3D, RPL26L1, POLR2K, KIF11, CDC20, CCNB1, CCNA2, PUF60, SNRNP70, AKT1 and PRPF40A). Survival analysis revealed that seven genes (KIF11, CDC20, CCNB1, CCNA2, PRPF40A, CD3D and PUF60) were associated with overall survival time (p < 0.05). CONCLUSIONS: The blue module may play a vital role in the pathogenesis of MCL. Five real hub genes (KIF11, CDC20, CCNB1, CCNA2 and PUF60) were identified as potential prognostic biomarkers as well as therapeutic targets with clinical utility for MCL.

Co-Inhibition of the Immunoproteasome Subunits LMP2 and LMP7 Ameliorates Immune Thrombocytopenia.

The immunoproteasome, a special isoform of the 20S proteasome, is expressed when the cells receive an inflammatory signal. Immunoproteasome inhibition proved efficacy in the treatment of autoimmune diseases. However, the role of the immunoproteasome in the pathogenesis of immune thrombocytopenia (ITP) remains unknown. We found that the expression of the immunoproteasome catalytic subunit, large multifunctional protease 2 (LMP2), was significantly upregulated in peripheral blood mononuclear cells of active ITP patients compared to those of healthy controls. No significant differences in LMP7 expression were observed between patients and controls. ML604440, an specific LMP2 inhibitor, had no significant impact on the platelet count of ITP mice, while ONX-0914 (an inhibitor of both LMP2 and LMP7) increased the number of platelets. In vitro assays revealed that ONX-0914 decreased the expression of FcγRI in ITP mice and decreased that of FcγRIII in ITP patients, inhibited the activation of CD4+ T cells, and affected the differentiation of Th1 cells in patients with ITP. These results suggest that the inhibition of immunoproteasome is a potential therapeutic approach for ITP patients.

Association between common polymorphisms in ERCC gene and prognosis of osteosarcoma in patients treated with chemotherapy: a meta-analysis.

PURPOSE: Some previous studies have sought to investigate the roles of excision repair cross complementation group 1 (ERCC1), ERCC2, ERCC4, and ERCC5 gene polymorphisms in the prognosis of osteosarcoma patients. However, their results were inconclusive. Here, we performed a meta-analysis to determine the strength of the association between eight polymorphisms in the ERCC genes (rs11615, rs3212986, rs2298881, rs13181, rs1799793, rs1800067, rs2296147, and rs1047768) and prognosis of osteosarcoma patients treated with chemotherapy. MATERIALS AND METHODS: We retrieved the relevant studies from PubMed, Embase, and Web of Science in human osteosarcoma published prior to July 2017. Primary outcomes included overall survival (OS) and event-free survival, expressed by hazard ratios (HRs) with their corresponding 95% CIs. STATA software (version 12.0) was utilized to perform data synthesis. RESULTS: A total of 13 eligible follow-up studies involving 2,303 patients met all the inclusion criteria, conducted in two populations of ethnic descent: 11 Asians and two Caucasians. In the present meta-analysis, we demonstrated that the homozygous variant genotypes in ERCC2 rs1799793 and ERCC5 rs2296147 were significantly associated with OS in osteosarcoma (TT vs GG for rs1799793: HR = 0.62, 95% CI = 0.41-0.93, Pheterogeneity = 0.310, I2 = 15.3%, P = 0.020; TT vs CC for rs2296147: HR = 0.42, 95% CI = 0.23-0.78, Pheterogeneity = 0.708, I2 = 0.0%, P = 0.006). In addition, no evidence of association was observed between prognosis in osteosarcoma and ERCC1 rs11615, ERCC1 rs3212986, ERCC1 rs2298881, ERCC2 rs13181, ERCC4 rs1800067, and ERCC5 rs1047768 polymorphisms. CONCLUSION: Our meta-analysis indicated that TT genotype in the ERCC2 rs1799793 and ERCC5 rs2296147 might prolong the survival time of patients with osteosarcoma, suggesting that the rs1799793 and rs2296147 polymorphisms can be used as predictors for prognosis of osteosarcoma patients treated with chemotherapy.

[Research Progress on Notch Signal Pathway in Acute Graft-Versus-Host Disease -Review].

The Notch signaling pathway is a highly conserved cell signaling system that plays an essential role in many biological processes. Notch signaling regulates multiple aspects of hematopoiesis, especially during T cell develop-ment. Recent data suggest that Notch also regulates mature T cell differentiation and function. The latest data show that Notch also plays an essential role in alloreactive T cells mediating acute graft-versus-host disease (aGVHD), the most severe complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT). Notch inhibition in donor-derived T cells or blockade of individual Notch ligands and receptors after transplantation can reduce GVHD severity and mortality in mouse models of allo-HSCT, without causing global immunosuppression. These findings indicate Notch in T cells as an attractive therapeutic target to control aGVHD. In this article, the pathophysiology of aGVHD, the Notch signal pathway and aGVHD are reviewed.

Severe aplastic anemia preceding acute monocytic leukemia in an adult with acquired trisomy 21: A case report.

The current case report presents a patient with acute monocytic leukemia (AML-M5) occurring 14 years following the successful treatment of severe aplastic anemia (SAA) with immunosuppressants and androgens. The patient was treated with induction chemotherapy, but did not achieve remission. The patient succumbed to central nervous system bleeding 2 weeks following the first cycle of chemotherapy. Chromosomal examination revealed 47,XX,+21[10]/46,XX[1]. To the best of our knowledge the present case is the first to be reported of SAA 14 years preceding AML-M5 with acquired trisomy 21.

[Inhibitory effects of gamma secretase inhibitor on human multiple myeloma xenograft mouse model].

OBJECTIVE: To explore the tumor growth inhibition of gamma secretase inhibitor MRK003 on human multiple myeloma xenograft mice by inhibition of AKT and Notch1 expression. METHODS: NOD/SCID mice were injected with human multiple myeloma cell lines RPMI8226 to establish a xenograft mouse model. Mice were randomized into two groups：the experimental group were injected with MRK003 at a dose of 5 mg× kg⁻¹×d⁻¹ for 14 days; the inhibitor was replaced by an equal saline in the control group. Mice were sacrificed by cervical dislocation on the next day after the last injection and tumor tissue was removed to detect the expression of Notch1 and AKT by immunohistochemistry. RESULTS: After subcutaneous injection with RPMI8226, mice had tumor formation in 5-7 days and the largest tumor block in 10-12 days. Before RPMI8226 injection, the mean sizes of tumor block in the experimental and the control groups were 509.2 mm³, 511.2 mm³(P>0.05). 9 days after injection, the mean sizes of tumor tissue in the experimental and the control groups were 636.6 mm³, 691.2 mm³(P<0.01). On the next day after the last injection, the tumor sizes of the experimental and the control groups were 683.5 mm³ and 1798.7 mm³(P<0.01). The size of tumor block in the experimental group was significantly smaller than that of the control group(P<0.01). Immunohistochemistry staining showed that the positive expression rates of Notch1(11.1%, P<0.01) and AKT(13.3%, P<0.01) in experimental group were significantly decreased compared with the control group(Notch1: 95.6%; AKT: 93.3%). Western blot results showed that Notch1 and AKT protein in experimental group were significantly lower than those in the control group. CONCLUSION: MRK003 could inhibit the tumor growth of human multiple myeloma xenograft mice by downregulated expression of Notch1 signaling pathway.

NOTCH and phosphatidylinositide 3-kinase/phosphatase and tensin homolog deleted on chromosome ten/AKT/mammalian target of rapamycin (mTOR) signaling in T-cell development and T-cell acute lymphoblastic leukemia.

Activating mutations in NOTCH1 consitute the most prominent genetic abnormality in T-cell acute lymphoblastic leukemia (T-ALL). However, most T-ALL cell lines with NOTCH1 mutations are resistant to treatment with γ-secretase inhibitors (GSIs). The spotlight is now shifting to the phosphatidylinositide 3-kinase (PI3K)/phosphatase and tensin homolog deleted on chromosome ten (PTEN)/AKT/mammalian target of rapamycin (mTOR) pathway as another key potential target. These two signaling routes are deregulated in many types of cancer. In this review we discuss these two pathways with respect to their signaling mechanisms, functions during T-cell development, and their mutual roles in the development of T-ALL.