Overall survival of patients with CLL treated with ibrutinib in the first line compared to second-line ibrutinib after chemotherapy/chemoimmunotherapy.

OBJECTIVE: To evaluate the overall survival (OS) of patients with chronic lymphocytic leukemia (CLL) receiving either ibrutinib monotherapy as a first-line (1L) treatment or chemotherapy/chemoimmunotherapy-based (CT/CIT) regimens in 1L followed by ibrutinib in the second line (1L CT/CIT-2L ibrutinib) after disease progression by emulating a randomized trial comparing both treatment sequences. METHODS: Patient-level data from the RESONATE-2 trial (NCT01722487) and real-world PHEDRA databases were analyzed. Three scenarios were considered using the following data sources: (1) RESONATE-2, (2) combined RESONATE-2/PHEDRA, (3) combined RESONATE-2/PHEDRA for 1L ibrutinib and PHEDRA for 1L CT/CIT-2L ibrutinib. Propensity score-based weights and inverse probability of censoring weighting were used to adjust for baseline (Scenarios 2 and 3) and time-dependent confounding (all scenarios), and to address potential biases. A weighted Cox proportional hazards model was used to estimate the OS hazard ratio (HR) and 95% confidence interval (CI) for 1L ibrutinib versus 1L CT/CIT-2L ibrutinib. RESULTS: Results from Scenario 1 showed a significantly lower risk of death with 1L ibrutinib compared with 1L chlorambucil followed by 2L ibrutinib (HR 0.35 [95% CI 0.20-0.62]). Results from Scenarios 2 and 3 demonstrated a reduced risk of death with 1L ibrutinib compared with 1L CT/CIT-2L ibrutinib (HR 0.35 [0.21-0.61] and 0.64 [0.39-1.04], respectively). CONCLUSION: The analyses consistently showed a reduced risk of death when ibrutinib was used as a 1L treatment in CLL compared with delaying its use until 2L after CT/CIT regimens, which suggests that initiating ibrutinib in 1L is advantageous for improving survival outcomes.

Mystique is a new insulin-like growth factor-I-regulated PDZ-LIM domain protein that promotes cell attachment and migration and suppresses Anchorage-independent growth.

By comparing differential gene expression in the insulin-like growth factor (IGF)-IR null cell fibroblast cell line (R- cells) with cells overexpressing the IGF-IR (R+ cells), we identified the Mystique gene expressed as alternatively spliced variants. The human homologue of Mystique is located on chromosome 8p21.2 and encodes a PDZ LIM domain protein (PDLIM2). GFP-Mystique was colocalized at cytoskeleton focal contacts with alpha-actinin and beta1-integrin. Only one isoform of endogenous human Mystique protein, Mystique 2, was detected in cell lines. Mystique 2 was more abundant in nontransformed MCF10A breast epithelial cells than in MCF-7 breast carcinoma cells and was induced by IGF-I and cell adhesion. Overexpression of Mystique 2 in MCF-7 cells suppressed colony formation in soft agarose and enhanced cell adhesion to collagen and fibronectin. Point mutation of either the PDZ or LIM domain was sufficient to reverse suppression of colony formation, but mutation of the PDZ domain alone was sufficient to abolish enhanced adhesion. Knockdown of Mystique 2 with small interfering RNA abrogated both adhesion and migration in MCF10A and MCF-7 cells. The data indicate that Mystique is an IGF-IR-regulated adapter protein located at the actin cytoskeleton that is necessary for the migratory capacity of epithelial cells.

PDLIM2 regulates transcription factor activity in epithelial-to-mesenchymal transition via the COP9 signalosome.

Epithelial cell differentiation and polarized migration associated with epithelial-to-mesenchymal transition (EMT) in cancer requires integration of gene expression with cytoskeletal dynamics. Here we show that the PDZ-LIM domain protein PDLIM2 (Mystique/SLIM), a known cytoskeletal protein and promoter of nuclear nuclear factor κB (NFκB) and signal transducer and activator of transcription (STAT) degradation, regulates transcription factor activity and gene expression through the COP9 signalosome (CSN). Although repressed in certain cancers, PDLIM2 is highly expressed in invasive cancer cells. Here we show that PDLIM2 suppression causes loss of directional migration, inability to polarize the cytoskeleton, and reversal of the EMT phenotype. This is accompanied by altered activity of several transcription factor families, including ß-catenin, Ap-1, NFκB, interferon regulatory factors, STATs, JUN, and p53. We also show that PDLIM2 associates with CSN5, and cells with suppressed PDLIM2 exhibit reduced nuclear accumulation and deneddylation activity of the CSN toward the cullin 1 and cullin 3 subunits of cullin-RING ubiquitin ligases. Thus PDLIM2 integrates cytoskeleton signaling with gene expression in epithelial differentiation by controlling the stability of key transcription factors and CSN activity.

Sequestration of PDLIM2 in the cytoplasm of monocytic/macrophage cells is associated with adhesion and increased nuclear activity of NF-kappaB.

PDLIM2 (Mystique/SLIM) is a postsynaptic density-95/discs large/zonula occludens-1-Lin-11, Isl-1, Mec-3 (PDZ-LIM) domain protein expressed in the nucleus of T lymphocytes, where it promotes degradation of the p65 subunit of NF-kappaB. It is also expressed at the cytoskeleton in epithelial cells, where it is essential for cell migration. It is not known whether PDLIM2 function at the nucleus and cytoskeleton is linked and whether PDLIM2 subcellular location is regulated in hematopoietic cells. To investigate this, we used the human monocytic leukemia cell line THP-1 that can differentiate into adherent macrophages and the adherent murine macrophage cell line RAW264.7. PMA-induced differentiation of THP-1 cells resulted in increased accumulation of PDLIM2. In differentiated cells, PDLIM2 exhibited retarded mobility indicative of serine phosphorylation, which could be reversed by phosphatases and by inhibition of protein kinase C or ERK kinases. In nondifferentiated THP-1 cells, PDLIM2 was located predominantly in the nucleus, whereas in differentiated cells, PDLIM2 was located predominantly in the cytoplasm. Suppression of PDLIM2 expression in THP-1 and RAW 264.7 cells resulted in decreased adhesion, increased NF-kappaB transcription reporter activity, and increased LPS-induced TNF-alpha production. Overexpression of PDLIM2 in THP-1 cells enhanced cell adhesion. Overall, these findings indicate that PDLIM2 sequestration in the cytoplasm is associated with cell adhesion and increased nuclear activity of NF-kappaB p65. The data suggest that sequestration of PDLIM2 at the cytoskeleton regulates its nuclear function.