Highly purified CD38 sub-populations show no evidence of preferential clonal evolution despite having increased proliferative activity when compared with CD38 sub-populations derived from the same chronic lymphocytic leukaemia patient

CD38 Multi-Functionality in Oral Squamous Cell Carcinoma: Prognostic Implications, Immune Balance, and Immune Checkpoint

Background

CD38 belongs to the ribosyl cyclase family and is expressed on various hematological cells and involved in immunosuppression and tumor promotion. Although targeting CD38 antibodies has been approved for treatment of multiple myeloma, the function of CD38 in solid tumor, oral squamous cell carcinoma (OSCC) etc., has not been investigated.

Methods

This retrospective study included 92 OSCC samples and analyzed the spatial distribution of CD38 by immunohistochemistry (IHC). The values of diagnosis and prognosis of CD38 were evaluated. Additionally, 53 OSCC preoperative peripheral blood samples were used to be analyzed by flow cytometry. Tumor Immune Estimation Resource (TIMER) and cBioPortal databases were used to study CD38 level in various tumors and its correlation with tumor immune microenvironment in head and neck squamous cell carcinoma (HNSCC).

Results

CD38 ubiquitously presented in tumor cells (TCs), fibroblast-like cells (FLCs), and tumor-infiltrating lymphocytes (TILs). Patients with highly expressed CD38 in TCs (CD38^TCs) had higher TNM stage and risk of lymph node metastasis. Upregulation of CD38 in FLCs (CD38^FLCs) was significantly associated with poor WPOI. Escalated CD38 in TILs (CD38^TILs) led to higher Ki-67 level of tumor cells. Moreover, patients with enhanced CD38^TCs were susceptible to postoperative metastasis occurrence, and those with highly expressed CD38^TILs independently predicted shorter overall and disease-free survival. Strikingly, patients with highly expressed CD38^TILs, but not CD38^TCs and CD38^FLCs, had significantly lower CD3⁺CD4⁺ T cells and higher ratio of CD3^-CD16⁺CD56⁺NK cells. The imbalance of immune system is attributed to dysregulated immune checkpoint molecules (VISTA, PD-1, LAG-3, CTLA-4, TIGIT, GITR) as well as particular immune cell subsets, which were positively correlated with CD38 expression in HNSCC.

Conclusion

CD38 is a poor prognostic biomarker for OSCC patients and plays a vital role in governing immune microenvironment and circulating lymphocyte homeostasis. Co-expression between CD38 and immune checkpoint molecules provides new insight into immune checkpoint therapy.

Ki-67 expression in mature B-cell neoplasms: a flow cytometry study

SUMMARY OBJECTIVE: Ki-67 is a nuclear protein associated with cellular proliferation in normal or leukemic conditions that can help identify more aggressive diseases and is usually evaluated with immunohistochemistry. The aim of this was to assess Ki-67 expression on mature B-cell neoplasms samples with flow cytometry immunophenotyping. METHOD: After surface staining with CD19 and CD45, intracellular staining for Ki-67 was performed in leukemic mature B-cells. Ki-67 expression was evaluated with flow cytometry. RESULTS: Ki-67 expression was higher in mantle cell lymphoma, Burkitt lymphoma, and diffuse large B-cell lymphoma cases. It was also associated with CD38 mean fluorescence intensity. CONCLUSIONS: Ki-67 expression evaluated by flow cytometry can be a useful tool in the diagnosis of mature B-cell neoplasms. More studies are needed to validate Ki-67 assessment with flow cytometry immunophenotyping.

The pathogenic relevance of the prognostic markers CD38 and CD49d in chronic lymphocytic leukemia

The interactions of chronic lymphocytic leukemia cells with the microenvironment in secondary lymphoid tissues and the bone marrow are known to promote CLL cell survival and proliferation. CD38 and CD49d are both independent prognostic risk parameters in CLL with important roles in shaping these interactions. Both are reported to influence CLL cell trafficking between blood and lymphoid organs as well as their survival and proliferation within the lymphoid organs, thereby impacting the pathophysiology of the disease. The expression of CD38 and CD49d is associated in the majority of cases, and they exist as part of macromolecular complexes. Here, we review the current evidence for the individual and associated contributions of these molecules to CLL pathophysiology.

p53 and cell cycle independent dysregulation of autophagy in chronic lymphocytic leukaemia

Background:

Activation of wild-type p53 with the small molecule sirtuin inhibitor Tenovin-6 (Tnv-6) induces p53-dependent apoptosis in many malignant cells. In contrast, Tnv-6 reduces chronic lymphocytic leukaemia (CLL) cell viability with dysregulation of autophagy, without increasing p53-pathway activity.

Methods:

Here, we have investigated whether a quiescent phenotype (unique to CLL) determines the Tnv-6 response, by comparing the effects of Tnv-6 on activated and proliferating CLL. We further studied if these responses are p53-dependent.

Results:

Unlike quiescent cells, cell death in activated cultures treated with Tnv-6 was consistently associated with p53 upregulation. However, p53 acetylation remained unchanged, without caspase-3 cleavage or apoptosis on electron microscopy. Instead, cellular ultrastructure and protein profiles indicated autophagy inhibition, with reduced ubiquitin–proteasome activity. In specimens with mutant TP53 cultured with Tnv-6, changes in the autophagy-associated protein LC3 occurred independently of p53. Cells treated with Tnv-6 analogues lacking sirtuin inhibitory activity had attenuated LC3 lipidation compared with Tnv-6 (P⩽0.01), suggesting that autophagy dysregulation occurs predominantly through an effect on sirtuins.

Conclusion:

These cell cycle and p53-independent anti-leukaemic mechanisms potentially offer novel therapeutic approaches to target leukaemia-sustaining cells in CLL, including in disease with p53-pathway dysfunction. Whether targets in addition to sirtuins contribute to autophagy dysregulation by Tnv-6, requires further investigation.

Telomere dysfunction and its role in haematological cancer

Observations in human tumours, as well as mouse models, have indicated that telomere dysfunction may be a key event driving genomic instability and disease progression in many solid tumour types. In this scenario, telomere shortening ultimately results in telomere dysfunction, fusion and genomic instability, creating the large-scale rearrangements that are characteristic of these tumours. It is now becoming apparent that this paradigm may also apply to haematological malignancies; indeed these conditions have provided some of the most convincing evidence of telomere dysfunction in any malignancy. Telomere length has been shown in several malignancies to provide clinically useful prognostic information, implicating telomere dysfunction in disease progression. In these malignancies extreme telomere shortening, telomere dysfunction and fusion have all been documented and correlate with the emergence of increased genomic complexity. Telomeres may therefore represent both a clinically useful prognostic tool and a potential target for therapeutic intervention.

CD38 and chronic lymphocytic leukemia: a decade later

This review highlights a decade of investigations into the role of CD38 in CLL. CD38 is accepted as a dependable marker of unfavorable prognosis and as an indicator of activation and proliferation of cells when tested. Leukemic clones with higher numbers of CD38(+) cells are more responsive to BCR signaling and are characterized by enhanced migration. In vitro activation through CD38 drives CLL proliferation and chemotaxis via a signaling pathway that includes ZAP-70 and ERK1/2. Finally, CD38 is under a polymorphic transcriptional control after external signals. Consequently, CD38 appears to be a global molecular bridge to the environment, promoting survival/proliferation over apoptosis. Together, this evidence contributes to the current view of CLL as a chronic disease in which the host's microenvironment promotes leukemic cell growth and also controls the sequential acquisition and accumulation of genetic alterations. This view relies on the existence of a set of surface molecules, including CD38, which support proliferation and survival of B cells on their way to and after neoplastic transformation. The second decade of studies on CD38 in CLL will tell if the molecule is an effective target for antibody-mediated therapy in this currently incurable leukemia.

Clinicobiologic importance of cytogenetic lesions in chronic lymphocytic leukemia

Molecular cytogenetic lesions play a major role in the pathogenesis of chronic lymphocytic leukemia (CLL) and represent important prognostic markers. Besides FISH, conventional banding analysis using effective mitogens is important for an accurate assessment of the cytogenetic profile of CLL. The most frequent aberrations are represented by 13q-, 11q-, +12, 6q- and 14q32/IGH translocations and 17p-. Chromosome translocations and complex karyotype may occur in up to 30 and 16% of the cases, respectively. The frequency of 17p- and 11q- is higher in patients requiring treatment and in relapsed/refractory patients, reflecting the association of these rearrangements with unfavorable prognosis. Mutations of the TP53 gene may also confer an inferior outcome, as is the case with 14q32 translocations and unbalanced translocations. Evidence was provided that distinct treatment approaches may be effective in specific cytogenetic entities of CLL, making molecular cytogenetic investigations a necessary tool for a modern diagnostic work-up in CLL.

Telomere dysfunction and fusion during the progression of chronic lymphocytic leukemia: evidence for a telomere crisis

We performed single-molecule telomere length and telomere fusion analysis in patients at different stages of chronic lymphocytic leukemia (CLL). Our work identified the shortest telomeres ever recorded in primary human tissue, reinforcing the concept that there is significant cell division in CLL. Furthermore, we provide direct evidence that critical telomere shortening, dysfunction, and fusion contribute to disease progression. The frequency of short telomeres and fusion events increased with advanced disease, but importantly these were also found in a subset of early-stage patient samples, indicating that these events can precede disease progression. Sequence analysis of fusion events isolated from persons with the shortest telomeres revealed limited numbers of repeats at the breakpoint, subtelomeric deletion, and microhomology. Array-comparative genome hybridization analysis of persons displaying evidence of telomere dysfunction revealed large-scale genomic rearrangements that were concentrated in the telomeric regions; this was not observed in samples with longer telomeres. The telomere dynamics observed in CLL B cells were indistinguishable from that observed in cells undergoing crisis in culture after abrogation of the p53 pathway. Taken together, our data support the concept that telomere erosion and subsequent telomere fusion are critical in the progression of CLL and that this paradigm may extend to other malignancies.

CD38 increases CXCL12-mediated signals and homing of chronic lymphocytic leukemia cells

Homing of chronic lymphocytic leukemia (CLL) cells to sites favoring growth, a critical step in disease progression, is principally coordinated by the CXCL12/CXCR4 axis. A cohort of 62 CLL patients was divided into migrating and nonmigrating subsets according to chemotaxis toward CXCL12. Migrating patients phosphorylated extracellular signal-regulated kinase 1/2 (ERK1/2) proteins more than nonmigrating patients (P<0.0002). CD38 expression was the parameter most strongly associated with heightened CXCL12 signaling (P<0.0001), confirmed by independent statistical approaches. Consistent with this observation, CD38(-) CLL cells in samples with bimodal CD38 expression responded less to CXCL12 than the intact clone (P=0.003). Furthermore, lentivirus-induced de novo expression of CD38 was paralleled by increased responses to CXCL12, as compared with cells infected with a control virus. CD38 ligation with agonistic monoclonal antibodies (mAbs) enhanced CXCL12 signaling, whereas blocking anti-CD38 mAbs inhibited chemokine effects in vitro. This is attributed to physical proximity on the membrane between CD38 and CXCR4 (the CXCL12 receptor), as shown by (i) coimmunoprecipitation and (ii) confocal microscopy experiments. Blocking anti-CD38 mAbs significantly compromised homing of CLL cells from blood to lymphoid organs in a mouse model. These results indicate that CD38 synergizes with the CXCR4 pathway and support the working hypothesis that migration is a central step in disease progression.

CD38/CD31 interactions activate genetic pathways leading to proliferation and migration in chronic lymphocytic leukemia cells

Human CD38 is a pleiotropic glycoprotein belonging to a family of enzymes/receptors involved in the catabolism of extracellular nucleotides. CD38-receptor activities are regulated through binding to the nonsubstrate ligand CD31. CD38 expression above a critical threshold is a negative prognostic marker for chronic lymphocytic leukemia (CLL) patients. Activation of CD38 by means of agonistic monoclonal antibodies or the CD31 ligand induces proliferation and immunoblast differentiation of CLL cells. Here we define the genetic signature that follows long-term in vitro interactions between CD38(+) CLL lymphocytes and CD31(+) cells. The emerging profile confirms that the CD31/CD38 axis activates genetic programs relevant for proliferative responses. It also indicates a contribution of this pathway to the processes mediating migration and homing. These results further support the notion that the CD31/CD38 axis is part of a network of accessory signals that modify the microenvironment, favoring localization of leukemic cells to growth-permissive sites.

In vivo intraclonal and interclonal kinetic heterogeneity in B-cell chronic lymphocytic leukemia

Clonal evolution and outgrowth of cellular variants with additional chromosomal abnormalities are major causes of disease progression in chronic lymphocytic leukemia (CLL). Because new DNA lesions occur during S phase, proliferating cells are at the core of this problem. In this study, we used in vivo deuterium ((2)H) labeling of CLL cells to better understand the phenotype of proliferating cells in 13 leukemic clones. In each case, there was heterogeneity in cellular proliferation, with a higher fraction of newly produced CD38+ cells compared with CD38- counterparts. On average, there were 2-fold higher percentages of newly born cells in the CD38+ fraction than in CD38- cells; when analyzed on an individual patient basis, CD38+ (2)H-labeled cells ranged from 6.6% to 73%. Based on distinct kinetic patterns, interclonal heterogeneity was also observed. Specifically, 4 patients exhibited a delayed appearance of newly produced CD38+ cells in the blood, higher leukemic cell CXC chemokine receptor 4 (CXCR4) levels, and increased risk for lymphoid organ infiltration and poor outcome. Our data refine the proliferative compartment in CLL based on CD38 expression and suggest a relationship between in vivo kinetics, expression of a protein involved in CLL cell retention and trafficking to solid tissues, and clinical outcome.

Probing the mitotic history and developmental stage of hematopoietic cells using single telomere length analysis (STELA)

In most human somatic cells, telomeres shorten as a function of DNA replication. Telomere length is therefore an indirect measure of the replicative history of cells. We measured the telomere lengths at XpYp chromosomes in purified human hematopoietic populations enriched for stem cells (Lin(-)CD34(+)CD38(-)Rho(-)) and successively more mature cells. The average telomere length showed expected length changes, pointing to the utility of this method for classifying novel differentiation markers. Interestingly, the frequency of abruptly shortened telomeres increased in terminally differentiated adult populations, suggesting that damage to telomeric DNA occurs or is not repaired upon hematopoietic differentiation. When Lin(-)CD34(+)CD38(-)Rho(-) cord blood cells were transplanted into immunodeficient mice, the telomeres of the most primitive regenerated human hematopoietic cells lost approximately 3 kb, indicative of more than 30 cell divisions. Further losses in differentiating cells were similar to those observed in pretransplantation cell populations. These results indicate extensive self-renewal divisions of human hematopoietic stem cells are the primary cause of telomere erosion upon transplantation rather than added cell divisions in downstream progenitors.