p66Shc deficiency in the Eμ-TCL1 mouse model of chronic lymphocytic leukemia enhances leukemogenesis by altering the chemokine receptor landscape

Abstract

The Shc family adaptor p66Shc acts as a negative regulator of proliferative and survival signals triggered by the B-cell receptor and, by enhancing the production of reactive oxygen species, promotes oxidative stress-dependent apoptosis. Additionally, p66Shc controls the expression and function of chemokine receptors that regulate lymphocyte traffic. Chronic lymphocytic leukemia cells have a p66Shc expression defect which contributes to their extended survival and correlates with poor prognosis. We analyzed the impact of p66Shc ablation on disease severity and progression in the Eμ-TCL1 mouse model of chronic lymphocytic leukemia. We showed that Eμ-TCL1/p66Shc−/− mice developed an aggressive disease that had an earlier onset, occurred at a higher incidence and led to earlier death compared to that in Eμ-TCL1 mice. Eμ-TCL1/p66Shc−/− mice displayed substantial leukemic cell accumulation in both nodal and extranodal sites. The target organ selectivity correlated with upregulation of chemokine receptors whose ligands are expressed therein. This also applied to chronic lymphocytic leukemia cells, where chemokine receptor expression and extent of organ infiltration were found to correlate inversely with these cells’ level of p66Shc expression. p66Shc expression declined with disease progression in Eμ-TCL1 mice and could be restored by treatment with the Bruton tyrosine kinase inhibitor ibrutinib. Our results highlight p66Shc deficiency as an important factor in the progression and severity of chronic lymphocytic leukemia and underscore p66Shc expression as a relevant therapeutic target.

Optimization of Organotypic Cultures of Mouse Spleen for Staining and Functional Assays

“…Samples were homogenized in 1.5 ml microtubes using polypropylene double-ended pestle (Sigma-Aldrich) in 350 µl RLT lysis buffer of the RNeasy Mini Kit (Qiagen) until completely homogenized. RNA was then extracted and retrotranscribed as described (12). RNA amount and quality were assessed using QIAxpert System (Qiagen).…”

Regulation of Selective B Cell Autophagy by the Pro-oxidant Adaptor p66SHC

“…Since both expression levels and phosphorylation status contribute to the metabolism-related function of p66SHC (Soliman et al, 2014), these factors are likely to have a major impact on its pro-autophagic function. Interestingly, we have previously reported that p66SHC expression is severely impaired in CLL B cells, a defect that contributes via multiple pathways to the abnormally extended survival of these cells (Capitani et al, 2010;Patrussi et al, 2019). This pathological setting is ideal to address the molecular mechanisms coordinated by p66SHC that contribute to leukemogenesis through the functional interplay between ROS and autophagy.…”

“…p66SHC deficiency is also as a causal factor in the development and severity of B cell chronic lymphocytic leukemia (B-CLL) (Capitani et al, 2010;Patrussi et al, 2019). B-CLL is the most common B cell neoplasm in the Western world, characterized by the accumulation of long-lived leukemic B cells in blood, bone marrow and secondary lymphoid organs (Hallek et al, 2018).…”

“…The pro-oxidant activity of p66SHC is also implicated in this function as it is able to modulate in opposite directions the expression of the homing receptor CCR7 and of the sphingosine-1 phosphate receptor S1PR1, which drives B cell exit from lymphoid tissues. Excessive expression and signaling by homing receptors, together with defective expression of S1PR1, favor the residency of the p66SHC-deficient leukemic cells in the pro-survival and chemioprotective lymphoid niche (Capitani et al, 2010;Patrussi et al, 2018Patrussi et al, , 2019.…”

“…p66SHC also inhibits chemokine receptor signaling in B cells at multiple levels, thereby impinging on their traffic to the pro-survival lymphoid tissues. Not surprisingly, p66SHC deficiency is associated with pathogenic outcomes, including autoimmunity and leukemia (Finetti et al, 2008;Capitani et al, 2010;Patrussi et al, 2019). We have recently reported a new role for p66SHC as regulator of B-cell autophagy/mitophagy and differentiation (Onnis et al, 2018).…”