The BH3-mimetic ABT-737 targets the apoptotic machinery in cholangiocarcinoma cell lines resulting in synergistic interactions with zoledronic acid. Cancer Chemother Pharmacol. 2011;67:557-567. [PMID: 20473610 DOI: 10.1007/s00280-010-1345-6]

The sphingosine kinase 2 inhibitor ABC294640 inhibits cervical carcinoma cell growth

ABC294640 is a specific sphingosine kinase 2 (SphK2) inhibitor. The anti-cervical carcinoma activity by ABC294640 was tested in this study. ABC294640 inhibited in vitro growth of the established (C33A and HeLa lines) and primary human cervical carcinoma cells. The SphK2 inhibitor also induced G1-S arrest and apoptosis in cervical carcinoma cells. It was yet non-cytotoxic to SphK2-low human cervical epithelial cells. ABC294640 inhibited SphK activation, causing sphingosine-1-phosphate depletion, signal transducer and activator of transcription 3 in-activation and ceramide production. Bcl-2 is a key resistance factor of ABC294640. Pharmacological Bcl-2 inhibition or Bcl-2 shRNA potentiated ABC294640-induced C33A cell growth inhibition and apoptosis. On the other hand, exogenous over-expression of Bcl-2 attenuated ABC294640's cytotoxicity against C33A cells. In vivo, ABC294640 administration inhibited C33A xenograft tumor growth in mice. Co-administration of the Bcl-2 inhibitor GDC-0199 further potentiated ABC294640's anti-tumor activity. Together, we suggest that ABC294640 might have translational value for the treatment of human cervical carcinoma.

Preferential targeting of cancer stem cells in the radiosensitizing effect of ABT-737 on HNSCC

Head and neck squamous cell carcinomas (HNSCC) are common human malignancies with poor clinical outcomes. The 5-year survival rates for patients with advanced stage HNSCC have not changed appreciably in the past few decades, underscoring a dire need for improved therapeutic options. HNSCC is frequently characterized by overexpression of anti-apoptotic Bcl-2 family members. Increased levels of these anti-apoptotic proteins have been associated with radio- and chemoresistance and poor clinical outcome. The aim of this study was to evaluate combined effects of radiation and ABT-737, a BH3-mimetic molecule, in HNSCC. Although ABT-737, as a single agent, was largely ineffective at promoting HNSCC cell death, we found that combining ABT-737 and radiation induced strong synergistic apoptosis in HNSCC cell lines and delayed tumoral growth in vivo. Moreover, we demonstrated for the first time that ABT-737, alone or in combination with radiation, can efficiently eliminate cancer stem cells (CSCs). Altogether, our results indicate that therapy targeting anti-apoptotic Bcl-2 family members could be a highly effective potential adjuvant to radiotherapy capable of targeting CSCs in HNSCC and therefore overcoming cancer recurrence and metastasis.

Bisphosphonates as potential adjuvants for patients with cancers of the digestive system

Best known for their anti-resorptive activity in bone, bisphosphonates (BPs) have generated interest as potential antineoplastic agents given their pleiotropic biological effects which include antiproliferative, antiangiogenic and immune-modulating properties. Clinical studies in multiple malignancies suggest that BPs may be active in the prevention or treatment of cancer. Digestive tract malignancies represent a large and heterogeneous disease group, and the activity of BPs in these cancers has not been extensively studied. Recent data showing that some BPs inhibit human epidermal growth factor receptor (HER) signaling highlight a potential therapeutic opportunity in digestive cancers, many of which have alterations in the HER axis. Herein, we review the available evidence providing a rationale for the repurposing of BPs as a therapeutic adjunct in the treatment of digestive malignancies, especially in HER-driven subgroups.

Mitochondrial outer membrane permeabilization increases reactive oxygen species production and decreases mean sperm velocity but is not associated with DNA fragmentation in human sperm

STUDY HYPOTHESIS

Does induction of mitochondrial outer membrane permeabilization (MOMP) in vitro affect specific functional parameters of human spermatozoa?

STUDY FINDING

Our findings show that MOMP induction increases intracellular reactive oxygen species (ROS) and decreases mean sperm velocity but does not alter DNA integrity.

WHAT IS KNOWN ALREADY

MOMP in somatic cells is related to a variety of apoptotic traits, such as alteration of mitochondrial membrane potential (ΔΨm), and increase in ROS production and DNA fragmentation. Although the presence of these apoptotic features has been reported in spermatozoa, to date the effects of MOMP on sperm function and DNA integrity have not been analysed.

STUDY DESIGN, SAMPLES/MATERIALS, METHODS

The study included spermatozoa from fertile donors. Motile sperm were obtained using the swim-up method. The highly motile sperm were collected and diluted with human tubal fluid to a final cell concentration of 5 × 10(6) ml(-1). To induce MOMP, selected sperm were treated at 37°C for 4 h with a mimetic of a Bcl-2 pro-apoptotic protein, ABT-737. MOMP was evaluated by relocating of cytochrome c. In addition, the effect of ABT-737 on mitochondrial inner membrane permeabilization was assessed using the calcein-AM/cobalt chloride method. In turn, ΔΨm was evaluated with JC-1 staining, intracellular ROS production with dihydroethidium, sperm motility was analysed by computer-assisted sperm analysis and DNA fragmentation by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL) assay. Measurements were performed by flow cytometry.

MAIN RESULTS AND THE ROLE OF CHANCE

MOMP was associated with ΔΨm dissipation (P < 0.05), increased ROS production (P < 0.05) and decreased mean sperm velocity (P < 0.05), but it was not associated with DNA fragmentation. MOMP did not induce a large increase in ROS, which could explain the negligible effect of MOMP on sperm DNA fragmentation under our experimental conditions.

LIMITATIONS, REASONS FOR CAUTION

The study was carried out in vitro using highly motile sperm, selected by swim-up, from healthy donors.

WIDER IMPLICATIONS OF THE FINDINGS

The results obtained in this study reveal that the alterations of sperm functions caused by MOMP are sufficiently relevant to justify its future study in male infertility.

LARGE SCALE DATA

None.

STUDY FUNDING AND COMPETING INTERESTS

The study was funded by grant DI12-0102 from the Universidad de La Frontera (J.V.V.) and a doctoral scholarship from CONICYT (F.T.). The authors declare no conflict of interest.

Prognostic impact of Bcl-2 depends on tumor histology and expression of MALAT-1 lncRNA in non-small-cell lung cancer

INTRODUCTION

Apoptosis is a crucial pathway in tumor growth and metastatic development. Apoptotic proteins regulate the underlying molecular cascades and are thought to modulate the tumor response to chemotherapy and radiation. However, the prognostic value of the expression of apoptosis regulators in localized non-small-cell lung cancer (NSCLC) is still unclear.

METHODS

We investigated the protein expression of apoptosis regulators Bcl-2, Bcl-xl, Mcl-1, and pp32/PHAPI, and the expression of the lncRNA MALAT-1 in tumor samples from 383 NSCLC patients (median age: 65.6 years; 77.5% male; paraffin-embedded tissue microarrays). For statistical analysis correlation tests, Log rank tests and Cox proportional hazard models were applied.

RESULTS

Tumor histology was significantly associated with the expression of Bcl-2, Bcl-xl and Mcl-1 (all p < 0.001). Among the tested apoptotic markers only Bcl-2 demonstrated prognostic impact (hazard ratio = 0.64, p = 0.012). For NSCLC patients with non-adenocarcinoma histology, Bcl-2 expression was associated with increased overall survival (p = 0.036). Besides tumor histology, prognostic impact of Bcl-2 was also found to depend on MALAT-1 lncRNA expression. Gene expression analysis of A549 adenocarcinoma cells with differential MALAT-1 lncRNA expression demonstrated an influence on the expression of Bcl-2 and its interacting proteins.

CONCLUSIONS

Bcl-2 expression was specifically associated with superior prognosis in localized NSCLC. An interaction of Bcl-2 with MALAT-1 lncRNA expression was revealed, which merits further investigation for risk prediction in resectable NSCLC patients.