The pterocarpanquinone LQB­118 compound induces apoptosis of cytarabine­resistant acute myeloid leukemia cells.

Acute myeloid leukemia (AML) is a complex hematological disorder characterized by blockage of differentiation and high proliferation rates of myeloid progenitors. Anthracycline and cytarabine­based therapy has remained the standard treatment for AML over the last four decades. Although this treatment strategy has increased survival rates, patients often develop resistance to these drugs. Despite efforts to understand the mechanisms underlying cytarabine resistance, there have been few advances in the field. The present study developed an in vitro AML cell line model resistant to cytarabine (HL­60R), and identified chromosomal aberrations by karyotype evaluation and potential molecular mechanisms underlying chemoresistance. Cytarabine decreased cell viability, as determined by MTT assay, and induced cell death and cell cycle arrest in the parental HL­60 cell line, as revealed by Annexin V/propidium iodide (PI) staining and PI DNA incorporation, respectively, whereas no change was observed in the HL­60R cell line. In addition, the HL­60R cell line exhibited a higher tumorigenic capacity in vivo compared with the parental cell line. Notably, no reduction in tumor volume was detected in mice treated with cytarabine and inoculated with HL­60R cells. In addition, western blotting revealed that the protein expression levels of Bcl­2, X­linked inhibitor of apoptosis protein (XIAP) and c­Myc were upregulated in HL­60R cells compared with those in HL­60 cells, along with predominant nuclear localization of the p50 and p65 subunits of NF­κB in HL­60R cells. Furthermore, the antitumor effect of LQB­118 pterocarpanquinone was investigated; this compound induced apoptosis, a reduction in cell viability and a decrease in XIAP expression in cytarabine­resistant cells. Taken together, these data indicated that acquired cytarabine resistance in AML was a multifactorial process, involving chromosomal aberrations, and differential expression of apoptosis and cell proliferation signaling pathways. Furthermore, LQB­118 could be a potential alternative therapeutic approach to treat cytarabine­resistant leukemia cells.

LQB­118 compound inhibits migration and induces cell death in glioblastoma cells.

Glioblastoma (GBM) is the most frequent malignant brain tumor. It represents the most aggressive astrocytoma with an overall survival of 14 months. Despite improvements in surgery techniques, radio­ and chemotherapy, most patients present treatment resistance, recurrence and disease progression. Therefore, development of effective alternative therapies is essential to overcome treatment failure. The purpose of the study was to evaluate the antitumoral activity of the synthetic compound LQB­118, in vitro. Monolayer and three­dimensional (3D) cell culture systems of human­derived GBM cell lines were used to evaluate the effect of LQB­118 on cell viability, cell death and migration. LQB­118 reduced cell viability as determined by MTT and trypan blue exclusion assays and promoted apoptosis in monolayer cell lines with an intrinsic temozolomide (TMZ)­resistance profile. In 3D culture models, LQB­118 reduced cell viability as evaluated by APH assay and inhibited cell migration while the TMZ resistance profile was maintained. Moreover, LQB­118 reduced p38 and AKT expression and phosphorylation, whereas it reduced only the phosphorylated ERK1/2 form. LQB­118 reduced p38 and NRF2 expression, an axis that is associated with TMZ resistance, revealing a mechanism to overcome resistance. LQB­118 also demonstrated an additional effect when combined with ionizing radiation and cisplatin. In conclusion, the present data demonstrated that LQB­118 maintained its effectiveness in a 3D cell conformation, which shares more similarities with the tumor mass. LQB­118 is a promising agent for GBM treatment as monotherapy and associated with radiotherapy or cisplatin. Its effect is associated with inhibition of GBM­related survival signaling pathways.

Estudo do mecanismo de ação do composto LQB-118 e do papel do miR-210 na radiorresistência e na classificação dos astrocitomas / [Study of the mechanism of action of the compound LQB-118 and the role of miR-210 in radioresistance and in the classification of astrocytomas]

O glioblastoma (GB) é um astrocitoma agressivo e letal e os pacientes possuem uma sobrevida média de 14 meses. O tratamento baseia-se em cirurgia seguida por radioterapia equimioterapia com temozolamida (TMZ). As altas taxas de recidiva e progressão tumoral estão relacionadas à resistência ao tratamento. O desenvolvimento de novas terapias mais efetivas é extremamente importante. O objetivo desse estudo foi analisar o papel do miR-210 na resposta ao novo composto sintético LQB-118 e na radiorresistência, in vitro, e naclassificação dos astrocitomas. Para tal, a atividade antitumoral de quatro novos compostos sintéticos, LQB-118, LQB-223, LQB-266 e LQB-268 foi avaliada por MTT na linhagem derivada de GB, U251-MG. O LQB-118 apresentou maior redução da viabilidade celular, sendo comparado a TMZ em outras linhagens celulares de GB, A172 e T98G, causandoefeitos similares ao observado na linhagem U251-MG. O LQB-118 induziu perda de adesão e morte celular avaliada por exclusão por azul de tripan, pela marcação de anexina V/PI por citometria de fluxo e pela redução da expressão pró-caspase-7 por Western blotting. A TMZ não induziu morte celular, demostrando a superioridade do tratamento com o LQB-118. Este composto reduziu os níveis proteicos de ERK e AKT e aumentou a expressão do miR-210,enquanto a TMZ reduziu a fosforilação de ERK de forma menos intensa, sugerindo regulação da expressão gênica pelo composto...

Glioblastoma (GB) is the most common astrocytoma and one of the most aggressive and lethal human malignancies. Patients present a median survival of 14 months. Surgeryfollowed by radiotherapy and chemotherapy with temozolomide (TMZ) are the first line treatment. Recurrence and tumor progression are related to treatment resistance and occurs in the majority of cases. Thus, development of more effective therapies becomes essential. Theaim of this study was to understand the role of miR-210 in response to treatment with new synthetic compound, LQB-118, and to ionizing radiation, in vitro. Furthermore, evaluate miR-210 importance in astrocitomas’ classification. To this end, U251-MG cell line was used to analyze the antitumoral activity of new synthetic compounds (LQB-118, LQB-223, LQB-266 and LQB-268) by MTT. LQB-118 demonstrated the highest effect on cell viability and itseffect was further evaluated in two more cell lines (T98G and A172) in comparison to TMZ. These cells demonstrated results similar to U251-MG cells. LQB-118 induced cell detachment and cell death assessed by trypan blue exclusion assay, by induction of annexin V labeling and reduction of pro-caspase-7 levels by flow cytometry and Western blotting,respectively. Moreover, TMZ did not significantly induce cell death, pointing out the superiority of LQB-118. In front of this, LQB-118 effect was evaluated in cell survival pathways AKT, ERK and microRNAs expression: miR-7, miR-143 and miR-210. LQB-118 reduced ERK1/2 and AKT expression, and enhanced miR-210 expression, suggesting geneexpression regulation by the compound. TMZ only slightly reduced ERK1/2 phosphorylation. As microRNAs are regulators of gene expression and miR-210 has a controversial role in literature, understanding its role in GB...

The pterocarpanquinone LQB-118 inhibits tumor cell proliferation by downregulation of c-Myc and cyclins D1 and B1 mRNA and upregulation of p21 cell cycle inhibitor expression.

The incidence of cancer grows annually worldwide and in Brazil it is the second cause of death. The search for anti-cancer drugs has then become urgent. It depends on the studies of natural and chemical synthesis products. The antitumor action of LQB-118, a pterocarpanquinone structurally related to lapachol, has been demonstrated to induce mechanisms linked to leukemia cell apoptosis. This work investigated some mechanisms of the in vitro antitumor action of LQB-118 on prostate cancer cells. LQB-118 reduced the expression of the c-Myc transcription factor, downregulated the cyclin D1 and cyclin B1 mRNA levels and upregulated the p21 cell cycle inhibitor. These effects resulted in cell cycle arrest in the S and G2/M phases and inhibition of tumor cell proliferation. LQB-118 also induced programmed cell death of the prostate cancer cells, as evidenced by internucleosomal DNA fragmentation and annexin-V positive cells. Except the cell cycle arrest in the S phase and enhanced c-Myc expression, all the mechanisms observed here for the in vitro antitumor action of LQB-118 were also found for Paclitaxel, a traditional antineoplastic drug. These findings suggest new molecular mechanisms for the LQB-118 in vitro antitumor action.