Commonly used caspase inhibitors designed based on substrate specificity profiles lack selectivity

Caspase regulation and activation have been extensively studied since the discovery of this class of proteases almost two decades ago, yet surprisingly few tools are available that can be used to monitor individual caspase activities [ 1 ]. The most commonly used tools include caspase-specific anti-sera as well as fluorogenic substrates and inhibitors. Unfortunately, antibody reagents often do not provide an accurate measure of caspase activity since several caspase family members （caspases 8/10 and 9） do not require proteolytic processing for activation [2, 3]. Furthermore, recent evidence suggests that caspase-7 （an executioner caspase） activation occurs via a catalytically active full-length intermediate that cannot be differentiated from the non-cleaved inactive zymogen using antibodies [4, 5].

Resistance mechanism to cisplatin in NCI-H460 non-small cell lung cancer cell line:investigating apoptosis,autophagy,and cytogenetic damage

Aim:To investigate the effects of cisplatin on the human non-small cell lung carcinoma(NCI-H460)cell line regarding cytotoxicity,genotoxicity,and expression of genes associated with apoptosis(BIRC5)and autophagy(BECN1).Methods:Cell cultures were treated with cisplatin concentrations(0.16-33.3μmol/L)for 48 h.Mutagenicity and acute and chronic cytotoxicities were assessed using the MTT,clonogenic,and cytokinesis-block micronucleus assays.Gene expression of BIRC5 and BECN1 was evaluated by reverse transcription-polymerase chain reaction.Results:Cisplatin IC50(0.33μmol/L)increased micronucleus frequency 2.50 times.Cisplatin was also cytotoxic in the 0.6-33.3μmol/L range,with reduced expression of the BIRC5 gene,suggesting induction of apoptosis.Besides reducing the expression of the BIRC5 gene,33.3μmol/L cisplatin increased the expression of the BECN1 gene,suggesting that autophagy can be related to cisplatin resistance.Conclusion:Cisplatin inhibited NCI-H460 growth,and cisplatin IC50 induced genotoxic damage.When higher cisplatin concentrations are used,the expression of genes associated with apoptosis and autophagy was changed.This results points to a further investigation of the role of autophagy in cisplatin resistance.

Osteolytic effects of tumoral estrogen signaling in an estrogen receptor-positive breast cancer bone metastasis model

Aim:Estrogen receptorα-positive(ER+)subtypes of breast cancer have the greatest predilection for forming osteolytic bone metastases(BMETs).Because tumor-derived factors mediate osteolysis,a possible role for tumoral ERαsignaling in driving ER+BMET osteolysis was queried using an estrogen(E2)-dependent ER+breast cancer BMET model.Methods:Female athymic Foxn1nu mice were inoculated with human ER+MCF-7 breast cancer cells via the left cardiac ventricle post-E2 pellet placement,and age-and dose-dependent E2 effects on osteolytic ER+BMET progression,as well as direct bone effects of E2,were determined.Results:Osteolytic BMETs,which did not form in the absence of E2 supplementation,occurred with the same frequency in young(5-week-old)vs.skeletally mature(16-week-old)E2(0.72 mg)-treated mice,but were larger in young mice where anabolic bone effects of E2 were greater.However,in mice of a single age and across a range of E2 doses,anabolic E2 bone effects were constant,while osteolytic ER+BMET lesion incidence and size increased in an E2 dose-dependent fashion.Osteoclasts in ER+tumor-bearing(but not tumor-naive)mice increased in an E2-dose dependent fashion at the bone-tumor interface,while histologic tumor size and proliferation did not vary with E2 dose.E2-inducible tumoral secretion of the osteolytic factor parathyroid hormone-related protein(PTHrP)was dose-dependent and mediated by ERα,with significantly greater levels of secretion from ER+BMET-derived tumor cells.Conclusion:These results suggest that tumoral ERαsignaling may contribute to ER+BMET-associated osteolysis,potentially explaining the greater predilection for ER+tumors to form clinically-evident osteolytic BMETs.

Mass cytometry uncovers a distinct peripheral immune profile and upregulated CD38 expression in patients with hidradenitis suppurativa

Hidradenitis suppurativa(HS)is a chronic inflammatory skin disease with a worldwide prevalence of 0.3–4.0%,wherein abscesses and dermal sinus tracts form in intertriginous skin[1].HS remains poorly treated due to a lack of knowledge regarding its immunopathogenesis[2].

Targeting multiple signaling pathways:the new approach to acute myeloid leukemia therapy

Acute myeloid leukemia(AML)is the most common form of acute leukemia in adults and the second most common form of acute leukemia in children.Despite this,very little improvement in survival rates has been achieved over the past few decades.This is partially due to the heterogeneity of AML and the need for more targeted therapeutics than the traditional cytotoxic chemotherapies that have been a mainstay in therapy for the past 50 years.In the past 20 years,research has been diversifying the approach to treating AML by investigating molecular pathways uniquely relevant to AML cell proliferation and survival.Here we review the development of novel therapeutics in targeting apoptosis,receptor tyrosine kinase(RTK)signaling,hedgehog(HH)pathway,mitochondrial function,DNA repair,and c-Myc signaling.There has been an impressive effort into better understanding the diversity of AML cell characteristics and here we highlight important preclinical studies that have supported therapeutic development and continue to promote new ways to target AML cells.In addition,we describe clinical investigations that have led to FDA approval of new targeted AML therapies and ongoing clinical trials of novel therapies targeting AML survival pathways.We also describe the complexity of targeting leukemia stem cells(LSCs)as an approach to addressing relapse and remission in AML and targetable pathways that are unique to LSC survival.This comprehensive review details what we currently understand about the signaling pathways that support AML cell survival and the exceptional ways in which we disrupt them.

Inhibition of Mcl-1 enhances cell death induced by the Bcl-2-selective inhibitor ABT-199 in acute myeloid leukemia cells

Acute myeloid leukemia(AML)is a serious disease.The 5-year survival rates remain frustratingly low(65%for children and 26%for adults).Resistance to frontline chemotherapy(usually cytarabine)often develops;therefore a new treatment modality is needed.Bcl-2 family proteins play an important role in balancing cell survival and apoptosis.The antiapoptotic Bcl-2 family proteins have been found to be dysregulated in AML.ABT-199,a BH3 mimetic,was developed to target antiapoptotic protein Bcl-2.Although ABT-199 has demonstrated promising results,resistance occurs.Previous studies in AML show that ABT-199 alone decreases the association of proapoptotic protein Bim with Bcl-2,but this is compensated by increased association of Bim with prosurvival protein Mcl-1,stabilizing Mcl-1,resulting in resistance to ABT-199.In this study,we investigated the antileukemic activity of the Mcl-1-selective inhibitor A-1210477 in combination with ABT-199 in AML cells.We found that A-1210477 synergistically induced apoptosis with ABT-199 in AML cell lines and primary patient samples.The synergistic induction of apoptosis was decreased upon Bak,Bax and Bim knockdown.While A-1210477 treatment alone also increased Mcl-1 protein levels,combination with ABT-199 reduced binding of Bim to Mcl-1.Our results demonstrate that sequestration of Bim by Mcl-1,a mechanism of ABT-199 resistance,can be abrogated by combined treatment with the Mcl-1 inhibitor A-1201477.

Inhibition of CDK9 by voruciclib synergistically enhances cell death induced by the Bcl-2 selective inhibitor venetoclax in preclinical models of acute myeloid leukemia

Venetoclax,an FDA-approved Bcl-2 selective inhibitor for the treatment of chronic lymphocytic leukemia and acute myeloid leukemia(AML),is tolerated well in elderly patients with AML and has good overall response rates;however,resistance remains a concern.In this study,we show that targeting CDK9 with voruciclib in combination with venetoclax results in synergistic antileukemic activity against AML cell lines and primary patient samples.CDK9 inhibition enhances venetoclax activity through downregulation of Mcl-1 and c-Myc.However,downregulation of Mcl-1 is transient,which necessitates an intermittent treatment schedule to allow for repeated downregulation of Mcl-1.Accordingly,an every other day schedule of the CDK9 inhibitor is effective in vitro and in vivo in enhancing the efficacy of venetoclax.Our preclinical data provide a rationale for an intermittent drug administration schedule for the clinical evaluation of the combination treatment for AML.

Targeting multiple signaling pathways:the new approach to acute myeloid leukemia therapy

Acute myeloid leukemia(AML)is the most common form of acute leukemia in adults and the second most common form of acute leukemia in children.Despite this,very little improvement in survival rates has been achieved over the past few decades.This is partially due to the heterogeneity of AML and the need for more targeted therapeutics than the traditional cytotoxic chemotherapies that have been a mainstay in therapy for the past 50 years.In the past 20 years,research has been diversifying the approach to treating AML by investigating molecular pathways uniquely relevant to AML cell proliferation and survival.Here we review the development of novel therapeutics in targeting apoptosis,receptor tyrosine kinase(RTK)signaling,hedgehog(HH)pathway,mitochondrial function,DNA repair,and c-Myc signaling.There has been an impressive effort into better understanding the diversity of AML cell characteristics and here we highlight important preclinical studies that have supported therapeutic development and continue to promote new ways to target AML cells.In addition,we describe clinical investigations that have led to FDA approval of new targeted AML therapies and ongoing clinical trials of novel therapies targeting AML survival pathways.We also describe the complexity of targeting leukemia stem cells(LSCs)as an approach to addressing relapse and remission in AML and targetable pathways that are unique to LSC survival.This comprehensive review details what we currently understand about the signaling pathways that support AML cell survival and the exceptional ways in which we disrupt them.