PTEN/PI3K/Akt pathway alters sensitivity of T-cell acute lymphoblastic leukemia to L-asparaginase

A metabolic synthetic lethality of phosphoinositide 3-kinase-driven cancer

The deregulated activation of the phosphoinositide 3-kinase (PI3K) pathway is a hallmark of aggressive tumors with metabolic plasticity, eliciting their adaptation to the microenvironment and resistance to chemotherapy. A significant gap lies between the biological features of PI3K-driven tumors and the specific targeting of their vulnerabilities. Here, we explore the metabolic liabilities of PI3K-altered T-cell acute lymphoblastic leukemia (T-ALL), an aggressive hematological cancer with dismal outcomes. We report a metabolic crosstalk linking glutaminolysis and glycolysis driven by PI3K signaling alterations. Pharmaceutical inhibition of mTOR reveals the singular plasticity of PI3K-altered cells toward the mobilization of glutamine as a salvage pathway to ensure their survival. Subsequently, the combination of glutamine degradation and mTOR inhibition demonstrates robust cytotoxicity in PI3K-driven solid and hematological tumors in pre-clinical and clinical settings. We propose a novel therapeutic strategy to circumvent metabolic adaptation and efficiently target PI3K-driven cancer.

Effect of 5-Aza-2'-deoxycytidine on T-cell acute lymphoblastic leukemia cell biological behaviors and PTEN expression

Objective

We currently face a sharp increase of T-cell acute lymphoblastic leukemia (T-ALL) incidence and a challenge of unmasking its complex etiology. The deoxycytidine analog 5-Aza-2'-deoxycytidine (5-Aza-dC) is currently the most common nucleoside methyltransferase inhibitor. The objective of this study was to clarify the role of 5-Aza-dC in T-ALL cell biological behaviors and phosphatase and tensin homolog deleted on chromosome ten (PTEN) expression.

Material and Methods

T-ALL cell lines were divided into the experimental group with 5-Aza-dC solution treatment, and the control group without treatment. PTEN methylation was detected using methylation-specific polymerase chain reaction (MS-PCR). Following the measurement of cell proliferation, viability, apoptosis, invasion, migration, etc., quantitative reverse transcription-polymerase chain reaction (PCR) was conducted to detect PTEN, DNA methyl-transferases (DNMT1), DNMT3a, MBD2, and MeCP2 expressions; Western blot to detect PTEN, PI3K, AKT, and mTOR protein expressions. In addition, rescue experiments to inhibit and restore the expression of PTEN in different groups were performed for further identification of the results in the former parts.

Results

MS-PCR results showed that in Jurkat cells, the target band was amplified using methylated primers for the PTEN gene promoter region; moreover, at 10 μmol/L of 5-Aza-dC for 24 h, PTEN methylation was completely removed without any un-methylated band observed. The experimental group had significantly lower cell proliferation and viability rates, higher apoptosis rates, decreased cell proportion in S phase, reduced invasion and migration; increased PTEN expression, decreased DNMT1, DNMT3a, MBD2, and MeCP2 mRNA expressions; and decreased PI3K, AKT, and mTOR protein expressions than those in the control group (all P < 0.05). Furthermore, according to the rescue experiment, silenced PTEN expression weakened the beneficial roles of 5-Aza-dC treatment, and resulted in significantly higher cell proliferation and viability rates, lower apoptosis rates, increased cell proportion in S phase, increased cell invasion and migration; decreased PTEN expression, elevated DNMT1, DNMT3a, MBD2, and MeCP2 mRNA expressions, and higher PI3K, AKT, and mTOR protein expressions (all P < 0.05). While restored PTEN expression enhanced functions of 5-Aza-dC treatment, leading to obviously lower cell proliferation and viability rates, higher apoptosis rates, increased cell proportion in G1 phase, and reduced cell invasion and migration; as well as increased PTEN expression, decreased DNMT1, DNMT3a, MBD2, and MeCP2 mRNA expressions, and lower PI3K, AKT, and mTOR protein expressions (all P < 0.05).

Conclusion

Demethylation treatment with 5-Aza-dC can inhibit T-ALL cell malignant biological behaviors and enhance the sensitivity to chemotherapy agents possibly, which may be related to the inhibited expressions of DNMT1, DNMT3a, MBD2, and MeCP2, and restored expression activity of PTEN to negatively regulate the PI3K/AKT signal transduction. Our silencing and restoration of PTEN expressions further support our findings, highlighting that demethylation with 5-Aza-dC to restore the anti-tumor activity of the tumor suppressor gene PTEN may be a promising therapeutic option for treating T-ALL.

The Role of PTEN in Chemoresistance Mediated by the HIF-1α/YY1 Axis in Pediatric Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is the most common childhood cancer. Current chemotherapy treatment regimens have improved survival rates to approximately 80%; however, resistance development remains the primary cause of treatment failure, affecting around 20% of cases. Some studies indicate that loss of the phosphatase and tensin homolog (PTEN) leads to deregulation of the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway, increasing the expression of proteins involved in chemoresistance. PTEN loss results in deregulation of the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and induces hypoxia-inducible factor 1-alpha (HIF-1α) expression in various cancers. Additionally, it triggers upregulation of the Yin Yang 1 (YY1) transcription factor, leading to chemoresistance mediated by glycoprotein p-170 (Gp-170). The aim of this study was to investigate the role of the PTEN/NF-κB axis in YY1 regulation via HIF-1α and its involvement in ALL. A PTEN inhibitor was administered in RS4;11 cells, followed by the evaluation of PTEN, NF-κB, HIF-1α, YY1, and Gp-170 expression, along with chemoresistance assessment. PTEN, HIF-1α, and YY1 expression levels were assessed in the peripheral blood mononuclear cells (PBMC) from pediatric ALL patients. The results reveal that the inhibition of PTEN activity significantly increases the expression of pAkt and NF-κB, which is consistent with the increase in the expression of HIF-1α and YY1 in RS4;11 cells. In turn, this inhibition increases the expression of the glycoprotein Gp-170, affecting doxorubicin accumulation in the cells treated with the inhibitor. Samples from pediatric ALL patients exhibit PTEN expression and higher HIF-1α and YY1 expression compared to controls. PTEN/Akt/NF-κB axis plays a critical role in the regulation of YY1 through HIF-1α, and this mechanism contributes to Gp-170-mediated chemoresistance in pediatric ALL.

Development of combination therapies with BTK inhibitors and dasatinib to treat CNS-infiltrating E2A-PBX1+/preBCR+ ALL

ABSTRACT

The t(1;19) translocation, encoding the oncogenic fusion protein E2A (TCF3)-PBX1, is involved in acute lymphoblastic leukemia (ALL) and associated with a pre-B-cell receptor (preBCR+) phenotype. Relapse in patients with E2A-PBX1+ ALL frequently occurs in the central nervous system (CNS). Therefore, there is a medical need for the identification of CNS active regimens for the treatment of E2A-PBX1+/preBCR+ ALL. Using unbiased short hairpin RNA (shRNA) library screening approaches, we identified Bruton tyrosine kinase (BTK) as a key gene involved in both proliferation and dasatinib sensitivity of E2A-PBX1+/preBCR+ ALL. Depletion of BTK by shRNAs resulted in decreased proliferation of dasatinib-treated E2A-PBX1+/preBCR+ cells compared with control-transduced cells. Moreover, the combination of dasatinib with BTK inhibitors (BTKi; ibrutinib, acalabrutinib, or zanubrutinib) significantly decreased E2A-PBX1+/preBCR+ human and murine cell proliferation, reduced phospholipase C gamma 2 (PLCG2) and BTK phosphorylation and total protein levels and increased disease-free survival of mice in secondary transplantation assays, particularly reducing CNS-leukemic infiltration. Hence, dasatinib with ibrutinib reduced pPLCG2 and pBTK in primary ALL patient samples, including E2A-PBX1+ ALLs. In summary, genetic depletion and pharmacological inhibition of BTK increase dasatinib effects in human and mouse with E2A-PBX1+/preBCR+ ALL across most of performed assays, with the combination of dasatinib and BTKi proving effective in reducing CNS infiltration of E2A-PBX1+/preBCR+ ALL cells in vivo.

Knockdown of miR-24 Suppressed the Tumor Growth of Cervical Carcinoma Through Regulating PTEN/PI3K/AKT Signaling Pathway

Cervical cancer (CC) is the most prevalent malignant tumor in gynecology. Despite routine surgery, advanced CC is hard to remove completely. MicroRNA-24 (miR-24) regulates several types of tumors, but its regulatory function in CC was previously unknown. We established stable knockdown of miR-24 and phosphatase and tensin homolog (PTEN) in CC cells. We measured mRNA and protein expression with RT-PCR and western blotting. We evaluated cell proliferation, invasion, migration, and apoptosis with CCK8, Transwell, wound healing, and flow cytometry, respectively. We also examined the influence of miR-24 and PTEN on tumor growth in a metastatic tumor model in nude mice. The expression of miR-24 was significantly increased in CC tissues and cell lines (C-33A, HeLa S3, SiHa). MiR-24 inhibitor greatly suppressed PTEN/PI3K/AKT, while miR-24 mimic markedly activated this signaling pathway. Knockdown of PTEN significantly reversed the effects of miR-24 inhibitor on cell proliferation, invasion, migration, and apoptosis of CC cells. The significant inhibition effect of tumor growth and ki67 expression caused by miR-24 inhibitor was reversed by si-PTEN. MiR-24 inhibitor significantly suppressed cell proliferation, invasion, migration, epithelial-mesenchymal transition (EMT) process, and tumor growth, while promoting cell apoptosis. However, the influence of miR-24 inhibitor was markedly reversed by si-PTEN. Targeting miR-24 could provide a novel therapeutic strategy for the prevention and treatment of CC.

Suppression of malignant melanoma by knocking down growth differentiation factor-15 via inhibiting PTEN/PI3K/AKT signaling pathway

Background: Melanoma is a highly malignant tumor, and it is characterized by high mortality. Growth differentiation factor 15 (GDF15) and PTEN/PI3K/AKT signaling pathway have been proved to be related with regulation of tumors. If GDF15 could regulate melanoma through targeting PTEN/PI3K/AKT signaling pathway remain unclear. Methods: EdU staining, wound healing, Transwell assay, and flow cytometry were performed to measure cell proliferation, migration, invasion, and apoptosis. GEPIA and TCGA data bases were applied to analyze the relationship between GDF15 and prognosis. Results: We found that high expression of GDF15 suggested lower survival of melanoma patients, and is positively linked with advanced stage through analysis with GEPIA and TCGA data bases. Knockdown of GDF15 greatly inhibited the migration, invasion and proliferation ability of both M14 and M21 cells, but promoted cell apoptosis. However, the influence of GDF15 on M14 and M21 cells were reversed by 740Y-P, the activator of PTEN/PI3K/AKT signaling pathway. In addition, 740Y-P significantly reversed the influence of sh-GDF15 on the epithelial-mesenchymal transition (EMT) related proteins expression in M14 and M21 cell lines. Significant higher expression of GDF15 in melanoma was observed. In addition, the inhibition of PTEN/PI3K/AKT signaling pathway by knocking down GDF15 was observed in both M14 and M21 cell lines. sh-GDF15 greatly decreased the resistance of M14 and M21 to chemotherapy drugs, docetaxel and doxorubicin. Conclusions: GDF15 regulated the cell proliferation, apoptosis, migration, invasion, and EMT process of M14 and M21 cell lines through targeting PTEN/PI3K/AKT signaling pathway. This research provides a novel prevention and treatment strategy for melanoma.

YBX1 as an oncogenic factor in T-cell acute lymphoblastic leukemia

Y-box-binding protein 1 (YBX1), a member of the RNA-binding protein family, is a critical regulator of cell survival in various solid tumors and acute myeloid leukemia. However, the function of YBX1 in T-cell acute lymphoblastic leukemia (T-ALL) remains elusive. Here, we found that YBX1 was upregulated in patients with T-ALL, T-ALL cell lines, and NOTCH1-induced T-ALL mice. Furthermore, depletion of YBX1 dramatically reduced cell proliferation, induced cell apoptosis, and induced G0/G1 phase arrest in vitro. Moreover, YBX1 depletion significantly decreased the leukemia burden in the human T-ALL xenograft and NOTCH1-induced T-ALL mice model in vivo. Mechanistically, downregulation of YBX1 markedly inhibited the expression of total AKT serine/threonine kinase (AKT), p-AKT, total extracellular signal-regulated kinase (ERK), and p-ERK in T-ALL cells. Taken together, our results uncovered a critical role of YBX1 in the leukemogenesis of T-ALL, which may have great potential as a biomarker and therapeutic target in T-ALL.

Vasoactive intestinal peptide exerts therapeutic action by regulating PTEN in a model of Sjögren's disease

INTRODUCTION

Sjögren's disease (SjD) is a chronic autoimmune disease characterized by the loss of the secretory function of the exocrine glands. At present, drugs that can both correct the immune imbalance and improve exocrine gland function are needed. Meanwhile, vasoactive intestinal peptide (VIP) has been reported as a candidate with anti-inflammatory and immunoregulatory properties for treating autoimmune diseases.

METHODS

Nonobese diabetic (NOD) mice and the primary splenic lymphocyte cells (SPLCs) were used to construct the SS model. The therapeutic effects of VIP for SjD by evaluating water consumption, histopathology, T cell subsets, and related cytokines. RT-qPCR and Western blot analysis were used to identify the expression of the PTEN/PI3K/AKT pathway.

RESULTS

We found that VIP therapy in NOD mice could increase the expression of PTEN and VIP/VPAC1 receptor, as well as decrease the PI3K/AKT pathway. In vitro, the results showed that the PTEN knockdown decreased the Treg/Th17 ratio and enhanced the phosphorylated PI3K/AKT pathway, which were reversed with VIP treatment.

CONCLUSIONS

VIP exerts potential therapeutic action in SjD by upregulating PTEN through the PI3K/AKT pathway and Treg/Th17 cell balance.

Possible mechanism of metabolic and drug resistance with L-asparaginase therapy in childhood leukaemia

L-asparaginase, which hydrolyzes asparagine into aspartic acid and ammonia, is frequently used to treat acute lymphoblastic leukaemia in children. When combined with other chemotherapy drugs, the event-free survival rate is 90%. Due to immunogenicity and drug resistance, however, not all patients benefit from it, restricting the use of L-asparaginase therapy in other haematological cancers. To solve the problem of immunogenicity, several L-ASNase variants have emerged, such as Erwinia-ASNase and PEG-ASNase. However, even when Erwinia-ASNase is used as a substitute for E. coli-ASNase or PEG-ASNase, allergic reactions occur in 3%-33% of patients. All of these factors contributed to the development of novel L-ASNases. Additionally, L-ASNase resistance mechanisms, such as the methylation status of ASNS promoters and activation of autophagy, have further emphasized the importance of personalized treatment for paediatric haematological neoplasms. In this review, we discussed the metabolic effects of L-ASNase, mechanisms of drug resistance, applications in non-ALL leukaemia, and the development of novel L-ASNase.

Targeting amino acid metabolism in cancer

Metabolic rewiring is a characteristic hallmark of cancer cells. This phenomenon sustains uncontrolled proliferation and resistance to apoptosis by increasing nutrients and energy supply. However, reprogramming comes together with vulnerabilities that can be used against tumor and can be applied in targeted therapy. In the last years, the genetic background of tumors has been identified thoroughly and new therapies targeting those mutations tested. Nevertheless, we propose that targeting the phenotype of cancer cells could be another way of treatment aiming to avoid drug resistance and non-responsiveness of cancer patients. Amino acid metabolism is part of the altered processes in cancer cells. Amino acids are building blocks and also sensors of signaling pathways regulating main biological processes. In this comprehensive review, we described four amino acids (asparagine, arginine, methionine, and cysteine) which have been actively investigated as potential targets for anti-tumor therapy. Asparagine depletion is successfully used for decades in the treatment of acute lymphoblastic leukemia and there is a strong implication to apply it to other types of tumors. Arginine auxotrophic tumors are great candidates for arginine-starvation therapy. Higher requirement for essential amino acids such as methionine and cysteine point out promising targetable weaknesses of cancer cells.