Drug induction apoptosis assay as predictive value of chemotherapy response in patients with B-cell chronic lymphocytic leukemia

Assessment of microRNA expression in leukemic cells as predictors of sensitivity to purine nucleoside analogs, fludarabine and cladribine, in chronic lymphocytic leukemia patients

Background: Great progress has been achieved lately in the therapy for chronic lymphocytic leukemia (CLL), one of the most frequently diagnosed adult leukemias. New classes of drugs, such as kinase inhibitors and BCL-2 protein antagonists, have been approved for treatment of CLL patients. Despite the abovementioned therapies the disease can still be effectively treated with purine nucleoside analogs (PNA). However, some patients, for example, those with TP53 gene abnormalities, become resistant, and the other factors involved in the therapy resistance are still being investigated. This study was aimed at analyzing the possible role of microRNAs as markers predicting the outcome of chemotherapy based on PNA – fludarabine and cladribine in CLL patients.

Methods: The expression of miR-21, miR-34a, miR-181a and miR-221 in previously separated leukemic cells was assessed with the use of qRQ-PCR technique at the moment of diagnosis in 40 CLL patients. In turn, apoptosis induced by fludarabine and cladribine in 24-hour cell culture was evaluated by determining the increase in the percentage of apoptotic cells of CD5+/CD19+/Cas3+ phenotype, using a flow cytometry method. Nine of the 40 studied subjects were treated with fludarabine-based regimens and were analyzed with regards to in vivo response to PNA.

Results: We detected a significantly higher PNA-induced apoptosis rate in patients with high miR-34a expression in comparison to low expression ones. Interestingly, such differences were detected particularly in standard cytogenetic patients.

Conclusions: These results may prove an important role of miR-34a expression as a predictor of apoptosis, even in cases when other risk factors like cytogenetic abnormalities are absent. An assessment of microRNAs expression seems to be useful as an indicator of sensitivity to PNA and may help to predict PNA-based therapy outcome.

The rate of in vitro fludarabine-induced peripheral blood and bone marrow cell apoptosis may predict the chemotherapy outcome in patients with chronic lymphocytic leukemia

Purpose

The problem of drug sensitivity and predicting the outcome of chemotherapy seems to be of great importance in hemato-oncological disorders. There are some factors that can help to predict effects of chemotherapy in chronic lymphocytic leukemia (CLL), such as presence of del17p, del11q, or TP53 gene mutations, which result in resistance to purine analogues and alkylating drugs. Despite the new therapeutic options introduced recently, purine analogues in combination with cyclophosphamide and the monoclonal antibody rituximab is still the gold standard for the first-line treatment of fit patients with CLL. The aim of this study was to assess whether the rate of apoptosis caused by one of purine analogues—fludarabine in cell cultures differs between patients who clinically respond to fludarabine-based chemotherapy and those who do not respond.

Methods

CLL leukemic cells, obtained from peripheral blood and bone marrow of 23 patients, were cultured in the presence of fludarabine. After 24 h of incubation, the rate of apoptosis, indicated by the expression of active caspase-3, was assessed with flow cytometry and then analyzed regarding clinical response to fludarabine-based regimens.

Results

The percentage of apoptotic cells induced by fludarabine was significantly higher in the group of patients who achieved remission in comparison to the group with no response to purine analogues therapy. Interestingly, we observed that among the patients who did not respond to chemotherapy, the presence of del17p and del11q was detected only once. Other non-responders had no detectable genetic abnormalities.

Conclusions

Based on these results, it can be presumed that in vitro drug sensitivity test, which is easy to perform, may predict the outcome of fludarabine-based chemotherapy in CLL patients.

Electronic supplementary material

The online version of this article (doi:10.1007/s00228-015-1893-0) contains supplementary material, which is available to authorized users.

Infrasound Sensitizes Human Glioblastoma Cells to Cisplatin-Induced Apoptosis

The development of nontoxic agents that can selectively enhance the cytotoxicity of chemotherapy is an important aim in oncology. This study evaluates the ability of infrasound exposure to sensitize glioblastoma cells to cisplatin-induced apoptosis. The infrasound was delivered using a device designed to replicate the unique infrasound emissions measured during external Qigong treatments. Human glioblastoma cell lines harboring wild-type p53 (U87) or mutant p53 (U251, SF210, and SF188) were treated in culture with cisplatin, infrasound emissions, or the combination of the 2 agents. Induction of apoptosis was quantified after 24 hours by flow cytometry following annexin V/propidium iodide staining. Infrasound emissions alone, delivered at moderate levels (~10 mPa) with dynamic frequency content (7-13 Hz), did not induce apoptosis, yet combining infrasound with cisplatin augmented the induction of apoptosis by cisplatin in all the 4 cell lines ( P < .05). Increased cellular uptake of the fluorophore calcein associated with infrasound exposure was quantified by fluorescence microscopy as well as flow cytometry, demonstrating increased cell membrane permeability. The 4 cell lines differed in the degree to which infrasound exposure increased calcein uptake, and these differences were predictive of the extent to which infrasound enhanced cisplatin-induced apoptosis. When exposed to specific frequencies, membrane permeabilization also appeared to be differentially responsive for each cell line, suggesting the potential for selective targeting of tissue types using isolated infrasonic frequencies. Additionally, the pressure amplitudes used in this study were several orders of magnitude less than those used in similar studies involving ultrasound and shock waves. The results of this study provide support for using infrasound to enhance the chemotherapeutic effects of cisplatin in a clinical setting.

Differential Staining Cytotoxicity assay: a review

Differential Staining Cytotoxicity (DiSC) assay is the prototype for a closely related family of assays based on the concept of total cell kill, or, in other words, cell death occurring in the entire population of tumor cells. It is probably the most versatile of the cell-death end points, in that it (1) can be applied to both solid and hematologic neoplasms, (2) can be applied to specimens in which it is not possible to obtain a pure population of highly enriched tumor cells, and (3) can be applied to a wide variety of drugs, ranging from traditional cytotoxic agents to biological response modifiers with activity mediated through tumor-infiltrating effector cells, to "targeted" kinase inhibitors, and to antivascular agents, such as bevacizumab and pazopanib. The basic principles of the assay are to culture three-dimensional fresh tumor cell clusters in anchorage-independent conditions. At the conclusion of the culture period, Fast Green dye is added to the microwells, the contents of which are then sedimented onto permanent Cytospin centrifuge slides and then counterstained with hematoxylin-eosin or Wright-Giemsa. "Living" cells stain with the cytologic stain in question and can be identified as either normal or neoplastic, based on standard morphologic criteria. "Dead" cells stain blue-green. Nonviable endothelial cells appear as strikingly hyperchromatic, blue-black, and often refractile objects, which may be readily distinguished from other types of dead cells. This assay has been biologically and clinically validated in a number of ways, as described in this chapter.

CD154 expression triggered by purine analogues in vitro: Correlation with treatment response and autoimmune events in chronic lymphocytic leukemia

OBJECTIVE

Despite a fludarabine-based treatment is the first choice of therapy in chronic lymphocytic leukemia (CLL), not all patients achieve a partial or complete response and some of them develop autoimmune manifestations. The aim of this study was to evaluate the influence of CD154 on these adverse effects because CD154 is involved in both B-cell survival and autoimmunity.

MATERIALS AND METHODS

Peripheral blood mononuclear cells (PBMC) from 36 patients with CLL were cultured in vitro with fludarabine or 2-chlorodeoxyadenosine for 24, 48, and 72 hours.

RESULTS

Seven patients (19.4%) presented CD154 expression in PBMC cultured with purine analogues in vitro for 24 and/or 48 hours, while no expression was found when cultured in media alone. These seven patients showed a decreased apoptotic rate in vitro after purine analogues compared with those patients who did not express CD154 (p = 0.01 for fludarabine; p < 0.001 for 2-chlorodeoxyadenosine). CD154 expression was found to have prognostic value for response to fludarabine in vivo and was associated with the development of autoimmune manifestations (odds ratio = 25; 95% confidence interval = 3.5-166.7; p < 0.001).

CONCLUSION

Our preliminary results suggest that CD154 expression in CLL patients, which may be induced by purine analogues, is associated with resistance to fludarabine and with development of autoimmune manifestations.

Impaired up-regulation of polo-like kinase 2 in B-cell chronic lymphocytic leukaemia lymphocytes resistant to fludarabine and 2-chlorodeoxyadenosine: a potential marker of defective damage response

The functional evaluation of ataxia telangiectasia mutated (ATM) and p53 was recently developed in B-cell chronic lymphocytic leukaemia (B-CLL), a disease in which the response to DNA damage is frequently altered. We identified a novel biomarker of chemosensitivity based on the induction of DNA damage by the purine nucleoside analogues (PNA) fludarabine and 2-chlorodeoxyadenosine (CdA). Using genome-wide expression profiling, it was observed that, in chemosensitive samples, PNA predominantly increased the expression of p53-dependent genes, among which PLK2 was the most highly activated at early time points. Conversely, in chemoresistant samples, p53-dependent and PLK2 responses were abolished. Using a quantitative real time polymerase chain reaction, we confirmed that PNA dose- and time-dependently increased PLK2 expression in chemosensitive but not chemoresistant B-CLL samples. Analysis of a larger cohort of B-CLL patients showed that cytotoxicity induced by PNA correlated well with PLK2 mRNA induction. Interestingly, we observed that failure to up-regulate PLK2 following PNA and chemoresistance were not strictly correlated with structural alterations in the TP53 gene. In conclusion, we propose that testing PLK2 activation after a 24-h incubation with PNA could be used to investigate the functional integrity of DNA damage-response pathways in B-CLL cells, and predict clinical sensitivity to these drugs.