PARP inhibition induces BAX/BAK-independent synthetic lethality of BRCA1-deficient non-small cell lung cancer

Evasion of apoptosis contributes to both tumourigenesis and drug resistance in non-small cell lung carcinoma (NSCLC). The pro-apoptotic BCL-2 family proteins BAX and BAK are critical regulators of mitochondrial apoptosis. New strategies for targeting NSCLC in a mitochondria-independent manner should bypass this common mechanism of apoptosis block. BRCA1 mutation frequency in lung cancer is low; however, decreased BRCA1 mRNA and protein expression levels have been reported in a significant proportion of lung adenocarcinomas. BRCA1 mutation/deficiency confers a defect in homologous recombination DNA repair that has been exploited by synthetic lethality through inhibition of PARP (PARPi) in breast and ovarian cells; however, it is not known whether this same synthetic lethal mechanism exists in NSCLC cells. Additionally, it is unknown whether the mitochondrial apoptotic pathway is required for BRCA1/PARPi-mediated synthetic lethality. Here we demonstrate that silencing of BRCA1 expression by RNA interference sensitizes NSCLC cells to PARP inhibition. Importantly, this sensitivity was not attenuated in cells harbouring mitochondrial apoptosis block induced by co-depletion of BAX and BAK. Furthermore, we demonstrate that BRCA1 inhibition cannot override platinum resistance, which is often mediated by loss of mitochondrial apoptosis signalling, but can still sensitize to PARP inhibition. Finally we demonstrate the existence of a BRCA1-deficient subgroup (11-19%) of NSCLC patients by analysing BRCA1 protein levels using immunohistochemistry in two independent primary NSCLC cohorts. Taken together, the existence of BRCA1-immunodeficient NSCLC suggests that this molecular subgroup could be effectively targeted by PARP inhibitors in the clinic and that PARP inhibitors could be used for the treatment of BRCA1-immunodeficient, platinum-resistant tumours.     

BAK1 gene variation and abdominal aortic aneurysms

We sought to examine the role of genetics in the multifactorial disease, abdominal aortic aneurysm (AAA), by studying sequence variation in the BAK1 gene (BAK1) that codes for an apoptotic‐promoting protein, as chronic apoptosis activation has been linked to AAA development and progression. BAK1 abdominal aorta cDNA from AAA patients and nondiseased individuals were compared with each other, as well as to the BAK1 genomic sequence obtained from matching blood samples. We found specific BAK1 single nucleotide polymorphism (SNP) containing alleles in both aneurysmic (31 cases) and healthy aortic tissue (5 cases) without seeing them in the matching blood samples. These same BAK1 SNPs have been reported, although rarely (average frequency <0.06%), in reference BAK1 DNA sequences. Based on this and other similar observations, we propose a novel hypothesis postulating that multiple variants of genes may preexist in “minority” forms within specific nondiseased tissues and be selected for, when intra‐ and/or extracellular conditions change. Therefore, the fact that different BAK1 variants can exist in both diseased and nondiseased AA tissues compared to matching blood samples, together with the rare occurrence of these same SNPs in reference sequences, suggests that selection may be a significant factor in AAA ontogeny. Hum Mutat 30:1–5, 2009. © 2009 Wiley‐Liss, Inc.     

双BAK椎间植骨融合术在治疗腰椎不稳症中的应用

目的：评价BAK椎间盘植骨融合对腰椎不稳症的治疗效果。方法：对38例腰椎不稳症患者采用前或后路BAK置入椎间单或多节段植骨融合，滑脱病例同时使用椎弓根钉复位固定，并经后路行椎管和神经根管减压。结果：36例随访8－32个月，平均15．8个月。滑脱复位率94．4％（34／36）；BAK融合率91．7％（33／36）。按0－9评分系统标准评定疗效；优11例，良21例，可4例，优良率88．9％，4例分别出现了伤口不愈合，窦道形成，滑脱复位不完全；假关节形成。结论：BAK能够提供节段稳定性及为椎间骨融合创造良好的生物力学环境，但在临床应用中必须严格掌握手术适应证及术中操作技巧。     

Molecular mechanisms of the antitumor activity of SB225002: A novel microtubule inhibitor

SB225002 (SB) is an IL-8 receptor B (IL-8RB) antagonist that has previously been shown to inhibit IL-8-based cancer cell invasion, and to possess in vivo anti-inflammatory and anti-nociceptive effects. The present study presented an evidence for the cell cycle-targeting activity of SB in a panel of p53-mutant human cancer cell lines of different origin, and investigated the underlying molecular mechanisms. A combination of cell cycle analysis, immunocytometry, immunoblotting, and RNA interference revealed that SB induced a BubR1-dependent mitotic arrest. Mechanistically, SB was shown to possess a microtubule destabilizing activity evidenced by hyperphosphorylation of Bcl₂ and Bcl_xL, suppression of microtubule polymerization and induction of a prometaphase arrest. Molecular docking studies suggested that SB has a good affinity toward vinblastine-binding site on β-tubulin subunit. Of note, SB265610 which is a close structural analog of SB225002 with a potent IL-8RB antagonistic activity did not exhibit a similar antimitotic activity. Importantly, in P-glycoprotein overexpressing NCI/Adr-Res cells the antitumor activity of SB was unaffected by multidrug resistance. Interestingly, the mechanisms of SB-induced cell death were cell-line dependent, where in invasive hepatocellular carcinoma HLE cells the significant contribution of BAK-dependent mitochondrial apoptosis was demonstrated. Conversely, SB activated p38 MAPK signaling in colorectal adenocarcinoma cells SW480, and pharmacologic inhibition of p38 MAPK activity revealed its key role in mediating SB-induced caspase-independent cell death. In summary, the present study introduced SB as a promising antitumor agent which has the potential to exert its activity through dual mechanisms involving microtubules targeting and interference with IL-8-drivin cancer progression.     

Revisiting Ocular Allergy: Evaluating Symptoms,Benzalkonium Chloride and Efficacy of Topical Ketotifen 0.025%

ABSTRACT

This interesting study raises a scientific issue for revisiting three important elements on diagnosis, use of preservatives and selection of the appropriate topical treatment. Itchy feeling can be encountered in other ophthalmic conditions misdiagnosed as allergy, benzalkonium chloride is responsible for surface toxicity resulting in reduced efficacy and tolerability of topical allergy medications and it should be avoided on the management of ocular allergy. Unpreserved ketotifen 0,025% has been shown to be the least toxic formulation being the optimum option for efficacy and tolerability on the management of ocular allergy.     

Intervertebral disc distraction with a laparoscopic anterior spinal fusion system

The BAK spinal fusion system has been applied to laparoscopic anterior lumbar interbody fusion. The system, consisting of a pair of cylindrical implants with threads, placed symmetrically about the sagittal plane, functions by tensioning the annulus fibrosis. Cylindrical plugs of increasing size are inserted prior to the implant placement. As the procedure may affect spinal posture and disc height, we measured changes due to incremental plug insertion using human cadaveric spine specimens (L5–S1, n = 4). Multi-directional flexibility of the construct was also measured as a function of plug size. The disc height change was found to increase initially and then to level off at 13-mm diameter plugs. In the sagittal plane, the intervertebral posture first shifted towards kyphotic then came back to the initial lordotic posture with plugs of bigger size. However, changes in disc height and spine posture were not statistically significant. Comparing the neutral zone (NZ) flexibility after inserting the plugs to the intact values, neither the flexion/extension nor the axial rotation NZ showed any singificant change. In lateral bending, the NZ decreased after the insertion of 13-mm plugs (p < 0.05). Insertion of plugs of increasing size from 9 mm to 12 mm decreased the range of motion (ROM) in all directions (p < 0.05). Insertion of 13-mm and 14-mm plugs decreased the flexion/ extension and lateral bending ROM, but not the axial rotation ROM, probably indicating some injury to the annulus fibers. Received: 8 March 1997 Revised: 8 September 1997 Accepted: 14 October 1997     

多节段腰椎滑脱手术治疗新术式探讨

目的：探讨一种新的使RF系统及BAK融合器治疗多节段腰椎滑脱的手术方法。方法：（1）常规后路彻底减压;（2）利用RF系统对下位滑脱椎体进行复位后植入一对BAK融合器;（3）同法对上位滑脱椎体进行复位后植入另外一对复位,临床症状消失;术后3个月和5个月随访临床症状和滑脱无复发,结论：后路减压利用RF系统行一期分段复位加椎体间BAK植入融合治疗多节段阶梯状腰椎滑脱,手术方法简单,手术一期完成,能恢复脊柱解剖连续性及腰骶部生物力学功能重建脊柱稳定性,优于其它手术方法。     

How to unleash mitochondrial apoptotic blockades to kill cancers?

Apoptosis, especially the intrinsic mitochondrial cell death pathway, is regulated by the BCL-2 family of proteins. Defects in apoptotic machinery are one of the main mechanisms that cells employ to evade cell death and become cancerous. Targeting the apoptotic defects, either by direct inhibition of BCL-2 family proteins or through modulation of regulatory pathways, can restore cell sensitivity to cell death. This review will focus on the aspects of BCL-2 family proteins, their interactions with kinase pathways, and how novel targeted agents can help overcome the apoptotic blockades. Furthermore, functional assays, such as BH3 profiling, may help in predicting responses to chemotherapies and aid in the selection of combination therapies by determining the mitochondrial threshold for initiating cell death.     

应用腰椎椎间融合器治疗下腰椎失稳症的临床体会

目的观察应用腰椎椎体间融合器 (BagbyKuslic ,BAK)治疗下腰椎失稳症的临床效果及适应证。方法对 6例因各种原因造成的下腰椎失稳症病人行后路双BAK椎间融合术。结果经术后 6～ 12个月随访 ,腰腿疼痛症状全部缓解 ,X线片示已出现椎体间骨性融合 ,未见BAK变形、滑脱及椎间塌陷、骨吸收现象。结论BAK是治疗下腰椎不稳症的一种较理想的内固定装置。