Chalcones against the hallmarks of cancer: a mini-review

Chalcones (1,3-diphenylpropen-1-ones) are a class of flavonoids that have been shown a broad spectrum of biological activities with therapeutic potential. Naturally occurring chalcones or synthetic chalcone derivatives have been extensively investigated as anticancer compounds. Cancer is still among the leading causes of death globally, although cancer treatments have improved over the past decades. Most of chemotherapeutic drugs target proliferating tumor cells; however, the cancer cells capabilities are also associated to tumor surround microenvironment. Thereby, the search of new compounds with a broad antitumor activity is still a great challenge. The cytotoxicity mechanisms of chalcones are beyond apoptosis induction in tumor cells, which make them promising compound for cancer therapy. In this mini-review we summarized recent studies that describe the anticancer potential of chalcones related to some of hallmarks of cancer. We shed a light on sustaining proliferative signaling, tumor-promoting inflammation, activating invasion and metastasis, inducing angiogenesis and resisting cell death.

Update on drug transporter proteins in acute myeloid leukemia: Pathological implication and clinical setting

Acute myeloid leukemia (AML) is one of the most common hematological neoplasia causing death worldwide. The long-term overall survival is unsatisfactory due to many factors including older age, genetic heterogeneity and molecular characteristics comprising additional mutations, and resistance to chemotherapeutic drugs. The expression of ABCB1/P-glycoprotein, ABCC1/MRP1, ABCG2/BCRP and LRP transporter proteins is considered the major reason for multidrug resistance (MDR) in AML, however conflicting data have been reported. Here, we review the main issues about drug transporter proteins in AML clinical scenario, and highlight the clinicopathological significance of MDR phenotype associated with ABCB1 polymorphisms and FLT3 mutation.

Detection of TNF-α Protein in Extracellular Vesicles Derived from Tumor Cells by Western Blotting

Detection of tumor necrosis factor-alpha (TNF-α) is usually performed in cell cultured medium or body fluids via measurement of its soluble extracellular form. However, depending on cellular condition, TNF-α might be transported through extracellular vesicles (EV) from donor cells to recipient cells. EV are small membrane-delimited structures (∼50 nm to 10 μm) that are spontaneously released from multiple cell types. In cancer, EV arise as important mediators in intercellular communication, and their molecular content may support tumor progression. This chapter describes methods to identify protein content in EV released from the tumor cell cultures. Through this protocol, we show first how to purify EV from in vitro cell culture by using differential centrifugation technique and then we demonstrate how to identify both membrane and soluble TNF-α forms in EV by Western blotting.

TNF-α Modulates P-Glycoprotein Expression and Contributes to Cellular Proliferation via Extracellular Vesicles

P-glycoprotein (Pgp/ABCB1) overexpression is associated with multidrug resistance (MDR) phenotype and, consequently, failure in cancer chemotherapy. However, molecules involved in cell death deregulation may also support MDR. Tumor necrosis factor-alpha (TNF-α) is an important cytokine that may trigger either death or tumor growth. Here, we examined the role of cancer cells in self-maintenance and promotion of cellular malignancy through the transport of Pgp and TNF-α molecules by extracellular vesicles (membrane microparticles (MP)). By using a classical MDR model in vitro, we identified a positive correlation between endogenous TNF-α and Pgp, which possibly favored a non-cytotoxic effect of recombinant TNF-α (rTNF-α). We also found a positive feedback involving rTNF-α incubation and TNF-α regulation. On the other hand, rTNF-α induced a reduction in Pgp expression levels and contributed to a reduced Pgp efflux function. Our results also showed that parental and MDR cells spontaneously released MP containing endogenous TNF-α and Pgp. However, these MP were unable to transfer their content to non-cancer recipient cells. Nevertheless, MP released from parental and MDR cells elevated the proliferation index of non-tumor cells. Collectively, our results suggest that Pgp and endogenous TNF-α positively regulate cancer cell malignancy and contribute to changes in normal cell behavior through MP.

Membrane microparticles: shedding new light into cancer cell communication

BACKGROUND

Microparticles (MPs) or ectosomes are small enclosed fragments (from 0.2 to 2 μm in diameter) released from the cellular plasma membrane. Several oncogenic molecules have been identified inside MPs, including soluble proteins XIAP, survivin, metalloproteinases, CX3CL1, PYK2 and other microRNA-related proteins; membrane proteins EGFR, HER-2, integrins and efflux pumps; and messenger RNAs and microRNAs miR-21, miR-27a, let-7, miR-451, among others. Studies have shown that MPs transfer their cargo to neoplastic or non-malignant cells and thus contribute to activation of oncogenic pathways, resulting in cell survival, drug resistance and cancer dissemination.

DISCUSSION AND CONCLUSION

This review summarizes recent findings on MP biogenesis and the role of the MPs cargo in cancer and discusses some of the RNAs and proteins involved. In addition, the discussion covers evidence of (1) how and which signaling pathways can be activated by MPs in recipient cells; (2) recipient cell-type selectivity in incorporation of proteins and RNAs transported by MPs; and (3) how upon stimulation, stromal cells release MPs, promoting resistance to chemotherapeutics and invasiveness in cancer cells.

Abstract A51: Antineoplastic activity of novel synthetic compound pterocarpanquinone LQB-118 in lung cancer cells

Introduction and objectives: Lung cancer is a significant health concern in many countries as it is the leading cause of cancer-related mortality worldwide. Although significant advances have been made in the treatment of this disease, either traditional chemotherapy or target agents fail to provide long-term benefits for the majority of patients. Intrinsic or acquired drug resistance is a major cause of failure in the treatment of lung cancer and remains an unsolved pharmacological problem. Therefore, the development of new therapies is needed to improve overall survival of these patients. The pterocarpanquinone LQB-118, a molecular hybrid structurally related to lapachol has emerged as a possible cytotoxic molecule for cancer cells by our group. This compound showed to be cytotoxic against leukemic cells regardless their multidrug resistance profiles while low toxicity was observed against normal peripheral blood mononucleated cells (PBMC). LQB-118 has already been patented in Brazil at National Institute of Industry Propriety under the code 020080139198. Although, cytotoxic effect of LQB-118 has been demonstrated in some tumor cells, the pathway through which this compound induces cell death remains unknown in lung cancer cells. Hence, in the present work, we analyzed the cell death process induced by LQB-118 in non-small cell lung cancer (NSCLC) cell line A549.

Materials and Methods: Cisplatin, is one of the most commonly used chemotherapeutic agent in the treatment of NSCLC and was used as comparision to LQB-118 effects. For this purpose we carried out a cell viability assay by MTT and a clonogenic survival assay by crystal violet. To study apoptosis induction by compounds the annexin-V/propidium iodide (PI) label, sub-G0 content/cell cycle profile and activation of caspase-3 were examined by FACS analysis. Western blot was performed to evaluate the capability of LQB-118 in changing the expression of some proteins involved in proliferative and antiapoptotic pathways signaling.

Results: We found that LQB-118 and cisplatin reduced cell viability in approximately 50% of cells at the concentration of 5μM after 48h of exposure and inhibited drastically colony formation. This cell viability reduction caused by LQB-118 was accompanied by an increase in the percentage of annexin-V/PI staining cells (around 30%) similar as observed for cisplatin. Activation of caspase-3 (around 25%) at 48h was also observed after LQB-118 exposure. However, the percentage of caspase-3 positive cells was higher after cisplatin treatment (around 60%). The new compound was also capable of inducing an arrest in G2/M cell cycle phase, however it was more pronounced in cisplatin treated cells. Interestingly, LQB-118 decreased significantly the expression of XIAP and survivin proteins, members of inhibitor of apoptosis proteins, responsible for drug resistance in several tumors. The inhibition of XIAP and survivin expression by LQB-118 was stronger than that observed for cisplatin treatment at 24h of culture. Analysis of epidermal growth factor receptor (EGFR) expression and proteins involved in signaling pathways downstream EGFR such as extracellular signal-regulated kinases 1/2 (ERK1/2) and Akt was also evaluated. No changes in EGFR expression or ERK1/2 phosphorilation were observed. Nevertheless, an inhibition of phosphorilated Akt was showed after LQB-118 treatment, suggesting that this compound acts inducing apoptosis through PI3Kinase pathway inhibition.

Conclusion: Our results suggest LQB-118 as a potential drug for NSCLC treatment once their effects in A549 cell line were similar that observed for cisplatin, with the advantage that LQB-118 seems to be less toxic than cisplatin in PBMC cells. Further studies are necessary to elucidate the mechanisms of action of this compound.

Financial support: INCT, FAPERJ, CNPq and Programa de Oncobiologia.

Citation Format: Karina Lani Silva, Paloma Silva de Souza, Paulo R.R. Costa, Raquel Ciuvalschi Maia. Antineoplastic activity of novel synthetic compound pterocarpanquinone LQB-118 in lung cancer cells. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr A51.

Microparticles induce multifactorial resistance through oncogenic pathways independently of cancer cell type

Multidrug resistance (MDR) is considered a multifactorial event that favors cancer cells becoming resistant to several chemotherapeutic agents. Numerous mechanisms contribute to MDR, such as P-glycoprotein (Pgp/ABCB1) activity that promotes drug efflux, overexpression of inhibitors of apoptosis proteins (IAP) that contribute to evasion of apoptosis, and oncogenic pathway activation that favors cancer cell survival. MDR molecules have been identified in membrane microparticles (MP) and can be transferred to sensitive cancer cells. By co-culturing MP derived from MDR-positive cells with recipient cells, we showed that sensitive cells accumulated Pgp, IAP proteins and mRNA. In addition, MP promoted microRNA transfer and NFκB and Yb-1 activation. Therefore, our results indicate that MP can induce a multifactorial phenotype in sensitive cancer cells.

XIAP and P-glycoprotein co-expression is related to imatinib resistance in chronic myeloid leukemia cells

P-glycoprotein (Pgp) and XIAP co-expression has been discussed in the process of the acquisition of multidrug resistance (MDR) in cancer. Here, we evaluated XIAP and Pgp expression in chronic myeloid leukemia (CML) samples, showing a positive correlation between them. Furthermore, we evaluated the effects of imatinib in XIAP and Pgp expression using CML cell lines K562 (Pgp(-)) and K562-Lucena (Pgp(+)). Imatinib increased XIAP and Pgp expression in K562-Lucena cells, while in K562 cells a downregulation of these proteins was observed, suggesting that imatinib induces an increment of MDR phenotype of CML cells that previously exhibit high levels of Pgp/XIAP co-expression.

Abstract 879: Multidrug resistant tumor cells-derived microparticles induce a multifactorial resistance phenotype through regulation of oncogenic-related pathways in sensitive cancer cells

Background: Multidrug resistance (MDR) is associated with unsuccessful clinical cancer treatment. Different proteins are enhanced in MDR including the efflux pump P-glycoprotein (Pgp/MDR1) and inhibitor of apoptosis proteins (IAP). Newly, it has been reported that Pgp and microRNAs (miR) associated with it can be transferred through of membrane microparticles (MPs) from MDR cells to sensitive cells. Based on that, we analyzed intercellular transfer of Pgp, IAPs (c-IAP1, survivin and XIAP) and miRs related to Pgp and tumorigenesis, from MDR cells to sensitive cells through MPs. Besides that, we also analyzed NFκB and YB-1 oncogenic pathway in sensitive cells after co-culture with MDR cells-derived MPs - both transcriptional Pgp and/or IAPs regulators.

Methods: MDR cells-derived MPs were isolated by ultracentrifugation, identified by flow citometry and analyzed for proteins (Pgp/MDR1 and IAPs) by Western blot, for mRNA (Pgp/MDR1 and IAPs) and for miRs (miR-27a, -451 and -21) by qRT-PCR. Sensitive cancer cells were co-culture with MDR cells for 24 separated by Transwell inserts, with isolated MPs, and culture with conditioned medium from MDR cells; and then analyzed for proteins (Pgp/MDR1, IAPs, IBα and YB-1), immunofluorescence (Pgp, NFκB and YB-1), mRNA (Pgp, IAPs and YB-1), miRs (miR-27a, -451 and -21), and drug resistance profile by annexin-V/PI staining.

Results: It was observed that MDR cells-derived MPs carry miR-27a, -451 and -21; Pgp and IAPs mRNA and proteins except for XIAP mRNA. After co-culture, sensitive cells acquired Pgp mRNA and protein and showed clusters of Pgp suggesting the presence of MPs. It was also observed an enhancement of IAPs (mRNA and protein) except for cIAP1; and a reduction of drug-inducible apoptosis index. No changes were observed in Pgp or IAPs in cells cultured with conditioned medium, which show that co-culture inducing proteins enhancement is not related with shedding soluble molecules by MDR cells. In parallel, we observed equivalent Pgp and IAPs enhancement when sensitive cells were co-culture with MDR cells-derived MPs, which show that co-culture inducing Pgp and IAPs changes are direct related with MPs. Also, sensitive cells co-cultured with MDR cells showed NFκB translocated to the nucleus and peri or nuclear YB-1 localization suggesting theirs participation on Pgp and IAPs endogenous expression. In addition, we observed an enhancement on miR-21, - 27a and -451, which also suggest a positive endogenous regulation of Pgp and IAPs.

Conclusion: Our data show that sensitive cells acquired multifactorial resistance through intercellular transfer of resistant cells-derived MPs, and suggest that oncogenic pathways could be involved with this phenomenon. These findings contribute to our knowledge for the emergence of MDR in cancer cells and could be helpful for new treatment approaches.

Citation Format: Paloma Silva de Souza, André L. de Souza Cruz, Joao Paulo de Biaso Viola, Raquel Ciuvalschi Maia. Multidrug resistant tumor cells-derived microparticles induce a multifactorial resistance phenotype through regulation of oncogenic-related pathways in sensitive cancer cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 879. doi:10.1158/1538-7445.AM2013-879

Cyclosporine A enables vincristine-induced apoptosis during reversal of multidrug resistance phenotype in chronic myeloid leukemia cells

Multidrug resistance (MDR) is considered a multifactorial phenotype which prevents a successful clinical cancer treatment. This phenomenon is mainly associated with mechanisms that include drug extrusion by P-glycoprotein (Pgp) overexpression and resistance to apoptosis derived by members of the inhibitor of apoptosis proteins (IAPs), such as XIAP. Studies have proposed the use of compounds that are able to inhibit or modulate Pgp function, with no changes in the physiological expression of this protein. Based on that, the present study aimed to evaluate the reversal of MDR phenotype through modulation of Pgp efflux pump activity in leukemia multidrug-resistant cells, using a low dose of cyclosporine A (CsA). We showed that modulation of Pgp activity by using CsA did not induce cytotoxic effects in leukemia cells, independently of Pgp expression. However, during the modulation condition, we could observe that vincristine-induced apoptosis was significant in resistant cells, which was also coupled with decreasing expression of the inhibitor of apoptosis protein XIAP. In summary, our data suggest that CsA is able to reversing MDR phenotype in vitro, inducing sensibility in multidrug-resistant cells with no alterations in Pgp expression. These findings contribute to our knowledge for the circumvention of MDR in cancer cells and could be helpful for new treatment approaches.

Variation of MDR proteins expression and activity levels according to clinical status and evolution of CML patients

The involvement of the multidrug resistance (MDR) mediated by ABC transporter proteins P-glycoprotein (Pgp) and multidrug resistance-associated protein-1 (MRP1) overexpressions in patients with chronic myeloid leukemia (CML) are not completely understood. Pgp and MRP1 expressions and activity were analyzed in samples from 158 patients with chronic myeloid leukemia (CML). Using flow cytometry, Pgp expression was more frequently observed in early chronic (P = 0.00) and in advanced (P = 0.02) CML phases when it was compared to MRP1 expression. Variation of MDR expression and activity were observed during the CML evolution in patients previously treated with interferon and imatinib. In the K562-Lucena cell line, Pgp positive, imatinib caused an enhancing in Pgp expression at protein and mRNA levels, whereas in the Pgp negative cell line, this drug was capable of decreasing MDR1/Pgp mRNA levels. Our result emphasizes the importance of understanding the different aspects of MDR status in patients with CML when they are under investigation in determining imatinib resistance.