Single‐cell profiling of pediatric T‐cell acute lymphoblastic leukemia: Impact of PTEN exon 7 mutation on PI3K/Akt and JAK–STAT signaling pathways

Abstract

Background: The PI3K/Akt/mTOR (PI3K) signaling pathway has a crucial role in T-cell acute lymphoblastic leukemias (T-ALLs). Although loss-of-function of phosphatase and tensin homolog (PTEN) is a common event in pediatric T-ALLs, the exact role of this tumor suppressor in TALL development has yet to be defined. Methods: Here, we report an optimized cytometric method for accurate proteomic profiling of TALL leukemic blasts at single-cell level. We determined the expression of PI3K and JAK-STAT signaling components in both primary and immortalized TALL cells as well as in normal T cells. Results: We observed that PTEN exon 7 mutated TALL cells retain a distinct PI3K activation; in particular, these cells show higher pAkt levels and a lower pS6 expression. Interestingly, we demonstrated for the first time that PTEN exon 7 mutated TALL are nonresponsive to IL7 in vitro as assessed by lack of pSTAT5 activation, although they do express IL7R. Conclusions: Phosphoflow analysis represents a fast, reliable, and accurate method to study the signaling profile of TALL. PTEN exon 7 mutated TALL cells are nonresponsive to IL7 in vitro suggesting that they may activate other mechanisms to support their viability and proliferation such as a higher constitutive PI3K/Akt signaling. Further investigations are necessary to elucidate the significance of this peculiar signaling behavior. Our observations should be taken into account in future studies aiming at molecular targeting of PI3K and/or JAK/STAT pathways for pharmacological intervention in TALL .

The pathogenesis and development of targeted drugs in acute T lymphoblastic leukaemia

“…Clinical trials have confirmed that forodesine is effective and less toxic in the treatment of recurrent or refractory T-cell leukaemia and also can be effective before and after allo-haematopoietic stem cell transplantation with minimal toxicity and without affecting potential graft versus leukaemia effect (Gandhi et al, 2005). way (Bonaccorso et al, 2020). Activated Akt signalling pathway driving T-acute lymphoblastic leukaemia cells resistance to glucocorticoids (Piovan et al, 2013).…”

“…Activated Akt signalling pathway driving T-acute lymphoblastic leukaemia cells resistance to glucocorticoids (Piovan et al, 2013). Abnormal mTOR can enhance the expression of hypoxia inducible factor HIF21α, promote the expression of vascular endothelial growth factor (VEGF) and accelerate tumour proliferation and metastasis (Bonaccorso et al, 2020).…”

“…A large number of animal experiments have confirmed that too many IL7–IL7R regulation signals further lead to the mutation or activation of JAK–STAT pathway‐related signal molecules (La Starza et al, 2018). The excessive activation and abnormal methylation of JAK–STAT pathway, TYK2 rearrangement (Tavakoli Shirazi et al, 2021) and hypermethylation of protein tyrosine phosphatase non‐receptor type 6 (PTPN6; Src homology region 2 domain‐containing phosphatase‐1 [SHP/NR0B2]), a negative regulator of JAK–STAT signalling pathway, will lead to excessive proliferation and abnormal apoptosis of leukaemic cells, promote the occurrence of T‐acute lymphoblastic leukaemia and also make T‐acute lymphoblastic leukaemia tumour cells resistant to chemotherapeutic drugs (Bonaccorso et al, 2020).…”

“…Abnormal expression of notch receptor 1 and functional mutation/deletion of tumour suppressor gene for component of PTEN can over activate the PI3K–Akt–mTOR signalling pathway and notch receptor 1 can antagonize PTEN and then activate Akt signalling pathway (Bonaccorso et al, 2020). Activated Akt signalling pathway driving T‐acute lymphoblastic leukaemia cells resistance to glucocorticoids (Piovan et al, 2013).…”

Issue Highlights – November 2020

“…T-lineage acute lymphoblastic leukemia [T-ALL] is an aggressive malignancy found both in pediatric [15%] and adult populations [25%]. Hyperactivation of the major signaling pathway PI3K/Akt commonly sustains leukemic cell viability in T-ALL and in the study byBonaccorso, et al, 2020, these investigators learn that PTEN Exon 7 mutated T-ALL cells do not respond to IL7, suggesting other mechanisms support the viability and growth of the tumor cells. What is relevant and exciting to our readership is that the proteomic profile of the pediatric T-ALL cases studied was accomplished by rapid and accurate phosphoflow cytometry rather than classical 'gold standard' western blotting.To assess the utility of flow cytometry in the diagnosis of malignant effusions due to non-hematopoietic neoplasmsWong-Arteta, et al, 2020 studied 101 patient samples [68 pleural effusions, 33 ascites] with markers directed towards CD9, CD45, CD99, CD71, CD56, CD10, CD81, CD200, EPCAM, CD14 and NG2.…”