In contrast to high CD49d, low CXCR4 expression indicates the dependency of chronic lymphocytic leukemia (CLL) cells on the microenvironment

The CIpP activator, TR-57, is highly effective as a single agent and in combination with venetoclax against CLL cells in vitro

Despite advances in treatment, a significant proportion of patients with chronic lymphocytic leukemia (CLL) will relapse with drug-resistant disease. The imipridones, ONC-201 and ONC-212, are effective against a range of different cancers, including acute myeloid leukemia (AML) and tumors of the brain, breast, and prostate. These drugs induce cell death through activation of the mitochondrial protease, caseinolytic protease (CIpP), and the unfolded protein response (UPR). Here we demonstrate that the novel imipridone analog, TR-57, has efficacy as a single agent and synergises with venetoclax against CLL cells under in vitro conditions that mimic the tumor microenvironment. Changes in protein expression suggest TR-57 activates the UPR, inhibits the AKT and ERK1/2 pathways and induces pro-apoptotic changes in the expression of proteins of the BCL-2 family. The study suggests that TR-57, as a single agent and in combination with venetoclax, may represent an effective treatment option for CLL.

CXCR4 overexpression in chronic lymphocytic leukemia associates with poorer prognosis: A prospective, single-center, observational study

Controversial data have been reported on the prognostic value of C-X-C motif chemokine receptor 4 (CXCR4) in chronic lymphocytic leukemia (CLL). This prospective, single-center, observational study aimed to evaluate the role of CXCR4 in the pathophysiology of CLL and its prognostic role. A total of 158 patients of CLL were enrolled, and CXCR4 expression on CLL cells was detected by flow cytometry (FCM) at initial diagnosis. The patients were divided into 2 groups according to the CXCR4 mean fluorescence intensity (MFI) median. Also, four patient specimens from the CXCR4low and CXCR4high groups were selected for RNASeq analysis. The progression-free survival (PFS) of CLL patients in the CXCR4high group was significantly shorter than the CXCR4low group, with a median follow-up time of 27 months (log-rank P < 0.001). Moreover, CXCR4 overexpression (MFI > 3376) was an independent marker of poor PFS in CLL patients (P < 0.001). Analysis of RNASeq results revealed that CXCR4 plays an important role in the migration of CLL. Collectively, CXCR4 expression levels on leukemia cells can be detected rapidly by FCM. CXCR4 overexpression was significantly associated with poorer prognosis in CLL patients within a shorter follow-up time.

The Role of the Microenvironment and Cell Adhesion Molecules in Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia (CLL) is a B-cell malignancy whose progression largely depends on the lymph node and bone marrow microenvironment. Indeed, CLL cells actively proliferate in specific regions of these anatomical compartments, known as proliferation centers, while being quiescent in the blood stream. Hence, CLL cell adhesion and migration into these protective niches are critical for CLL pathophysiology. CLL cells are lodged in their microenvironment through a series of molecular interactions that are mediated by cellular adhesion molecules and their counter receptors. The importance of these adhesion molecules in the clinic is demonstrated by the correlation between the expression levels of some of them, in particular CD49d, and the prognostic likelihood. Furthermore, novel therapeutic agents, such as ibrutinib, impair the functions of these adhesion molecules, leading to an egress of CLL cells from the lymph nodes and bone marrow into the circulation together with an inhibition of homing into these survival niches, thereby preventing disease progression. Several adhesion molecules have been shown to participate in CLL adhesion and migration. Their importance also stems from the observation that they are involved in promoting, directly or indirectly, survival signals that sustain CLL proliferation and limit the efficacy of standard and novel chemotherapeutic drugs, a process known as cell adhesion-mediated drug resistance. In this respect, many studies have elucidated the molecular mechanisms underlying cell adhesion-mediated drug resistance, which have highlighted different signaling pathways that may represent potential therapeutic targets. Here, we review the role of the microenvironment and the adhesion molecules that have been shown to be important in CLL and their impact on transendothelial migration and cell-mediated drug resistance. We also discuss how novel therapeutic compounds modulate the function of this important class of molecules.

Sialylation regulates migration in chronic lymphocytic leukemia

Sialylation is the terminal addition of sialic acid to underlying glycans. It plays a prominent role in cell adhesion and immune regulation. Sialylated structures found on adhesion molecules, such as CD49d, mediate the interactions between cancer cells and the microenvironment, facilitating metastatic seeding in target organs. Chronic lymphocytic leukemia (CLL) is a clonal B-cell malignancy characterized by the accumulation of CD5-positive B cells in the peripheral blood, bone marrow and lymph nodes. CLL cells proliferate mainly in the lymph node "proliferation centers", where the microenvironment provides pro-survival signals. Thus, migration and homing into these protective niches play a crucial role in CLL biology. In recent years, therapeutic strategies aimed at inducing the egress of CLL cells from the lymph nodes and bone marrow into the circulation have been highly successful. In this study, the sialylation status of 79 untreated and 24 ibrutinib-treated CLL patients was characterized by flow cytometry. Moreover, the effect of sialic acid removal on migration was tested by a transwell assay. Finally, we examined the sialylation status of CD49d by Western blot analysis. We found that CLL cells are highly sialylated, particularly those characterized by an "activated" immune phenotype. Notably, sialylation regulates CLL migration through the post-translational modification of CD49d. Finally, we showed that therapeutic agents that induce CLL mobilization from their protective niches, such as ibrutinib, modulate sialic acid levels. We propose that sialylation is an important regulator of CLL trafficking and may represent a novel target to further improve CLL therapy.

Lenalidomide abrogates the survival effect of bone marrow stromal cells in chronic lymphocytic leukemia

In the pathogenesis of chronic lymphocytic leukemia (CLL) the microenvironment plays an important role, as it produces survival signals and mediates drug resistance. Lenalidomide, which has immunomodulatory effect, can enhance the activation of T-, NK-cells and endothelial cells, however there are no data available whether it can modulate bone marrow stromal cells (BMSCs). In our study, we investigated the effects of lenalidomide on BMSCs and CLL cells. CLL cells were cultured alone or with BMSCs and were treated with lenalidomide. Apoptosis, immunophenotype, and cytokine secretion of BMSCs and CLL cells were determined by flow cytometry. Lenalidomide slightly increased the apoptosis of CLL cells and abrogated the anti-apoptotic effect of BMSCs on CLL cells. Lenalidomide treatment decreased the expression of antigens on CLL cells, which mediate the interactions with the microenvironment. Interestingly, lenalidomide enhanced the expression of IRF4 and the co-stimulatory molecule CD86. The secretion of several cytokines was not changed significantly by lenalidomide. CD49d-negative CLL cases were more sensitive to lenalidomide treatment. Our results suggest that lenalidomide has a limited effect on BMSCs, but it renders CLL cells more immunogenic and unresponsive to survival signals provided by BMSCs.

The significance of chemokines in diffuse large B-cell lymphoma: a systematic review and future insights

Despite the progress made in molecular and clinical research, patients with diffuse large B-cell lymphoma (DLBCL) still have a bad prognosis. Recently, chemokines/chemokine receptors have become the subject of interest in relation to DLBCL. Studies have demonstrated the important role of chemokines/chemokine receptors in the communication between DLBCL cells and tumor microenvironment. Studies have also reported the ability of chemokines/chemokine receptors in promoting the proliferation and invasion of DLBCL cells. Here, we summarize the data on mechanisms of DLBCL supporting the involvement of chemokine/chemokine receptor changes. We focus on the available evidence regarding chemokines/chemokine receptors as biomarkers and therapeutic targets for DLBCL.

The Effect of CD86 Expression on the Proliferation and the Survival of CLL Cells

Micro-environment plays important role in the pathogenesis of CLL by providing protective niche for CLL cells. Several molecules play important role in communication between CLL cells and immune cells like CD86.Some of the data suggest that CLL patients with high CD86 level need earlier treatments and cells with higher CD86 expression has higher proliferation rate but the role of CD86 in the survival and proliferation of CLL cells is unclear. We investigated the effect of CD86 expression to CLL cells in 50 peripheral blood and 15 lymph node biopsy samples from CLL patients. Our results showed that the expressions of CD86 increased significantly after 7 day culturing in medium, or in the presence of bone marrow stromal cells (BMSCs). We found positive correlation between CD86 and CD23 expression (p < 0.05), but no correlation with other markers. Furthermore, no correlation were found between the CD86 expression and the proliferation of CLL cells. Analysis of clinical data showed that cases with high CD86 expression had lower level of serum lymphocyte count (p < 0.04) at the time of the diagnosis. CD86 shows multiple appearances in the lymph nodes containing pseudofollicules, but no correlation was found between CD86 positivity, and Ki67 positivity. Our results suggest that the use of CD86 molecule as a proliferation marker for CLL is highly questionable. However, the CD86 molecule may interfere with the immune system of patients with CLL by activating and depleting immune functions. That can be the reason why CD86 positivity may mean worse prognosis.