Roscovitine synergizes with conventional chemo-therapeutic drugs to induce efficient apoptosis of human colorectal cancer cells

AIM： To examine the ability of cyclin-dependent kinase inhibitor （CDKI） roscovitine （Rosco） to enhance the antitumor effects of conventional chemotherapeutic agents acting by different mechanisms against human colorectal cancer. METHODS： Human colorectal cancer cells were treated, individually and in combination, with Rosco, taxol, 5-Fluorouracil （5-FU）, doxorubicine or vinblastine. The antiproliferative effects and the type of interaction of Rosco with tested chemotherapeutic drugs were determined. Cell cycle alterations were investigated by fluorescence-activated cell sorter FACS analysis. Apoptosis was determined by DNA fragmentation assay. RESULTS： Rosco inhibited the proliferation of tumor cells in a time-and dose-dependent manner. The efficacies of all tested chemotherapeutic drugs were markedly enhanced 3.0-8.42 × 10^3 and 130-5.28 × 10^3 fold in combination with 5 and 10 μg/mL Rosco, respectively. The combination of Rosco and chemotherapeutic drugs inhibited the growth of human colorectal cancer cells in an additive or synergistic fashion, and in a time and dose dependent manner. Rosco induced apoptosis and synergized with tested chemotherapeutic drugs to induce efficient apoptosis in human colorectal cancer cells. Sequential, inverted sequential and simultaneous treatment of cancer cells with combinations of chemotherapeutic drugs and Rosco arrested the growth of human colorectal cancer cells at various phases of the cell cycle as follows： Taxol/Rosco （G2/M-and S-phases）, 5-FU/Rosco （S-phase）, Dox/Rosco （S-phase） and Vinb/Rosco （G2/M-and S-phases）. CONCLUSION： Since the eff icacy of many anticancer drugs depends on their ability to induce apoptotic cell death, modulation of this parameter by cell cycle inhibi-tors may provide a novel chemo-preventive and chemo-therapeutic strategy for human colorectal cancer.     

Isolated Roux loop pancreaticojejunostomy versus pancreaticogastrostomy after pancreaticoduodenectomy: a prospective randomized study

Objectives

The optimal strategy for the reconstruction of the pancreas following pancreaticoduodenectomy (PD) is still debated. The aim of this study was to compare the outcomes of isolated Roux loop pancreaticojejunostomy (IRPJ) with those of pancreaticogastrostomy (PG) after PD.

Methods

Consecutive patients submitted to PD were randomized to either method of reconstruction. The primary outcome measure was the rate of postoperative pancreatic fistula (POPF). Secondary outcomes included operative time, day to resumption of oral feeding, postoperative morbidity and mortality, and exocrine and endocrine pancreatic functions.

Results

Ninety patients treated by PD were included in the study. The median total operative time was significantly longer in the IRPJ group (320 min versus 300 min; P = 0.047). Postoperative pancreatic fistula developed in nine of 45 patients in the IRPJ group and 10 of 45 patients in the PG group (P = 0.796). Seven IRPJ patients and four PG patients had POPF of type B or C (P = 0.710). Time to resumption of oral feeding was shorter in the IRPJ group (P = 0.03). Steatorrhea at 1 year was reported in nine of 42 IRPJ patients and 18 of 41 PG patients (P = 0.029). Albumin levels at 1 year were 3.6 g/dl in the IRPJ group and 3.3 g/dl in the PG group (P = 0.001).

Conclusions

Isolated Roux loop PJ was not associated with a lower rate of POPF, but was associated with a decrease in the incidence of postoperative steatorrhea. The technique allowed for early oral feeding and the maintenance of oral feeding even if POPF developed.     

Numerical Modeling and Analysis of Ti6Al4V Alloy Chip for Biomedical Applications

The influence of cutting forces during the machining of titanium alloys has attained prime attention in selecting the optimal cutting conditions to improve the surface integrity of medical implants and biomedical devices. So far, it has not been easy to explain the chip morphology of Ti6Al4V and the thermo-mechanical interactions involved during the cutting process. This paper investigates the chip configuration of the Ti6Al4V alloy under dry milling conditions at a macro and micro scale by employing the Johnson-Cook material damage model. 2D modeling, numerical milling simulations, and post-processing were conducted using the Abaqus/Explicit commercial software. The uncut chip geometry was modeled with variable thicknesses to accomplish the macro to micro-scale cutting by adapting a trochoidal path. Numerical results, predicted for the cutting reaction forces and shearing zone temperatures, were found in close approximation to experimental ones with minor deviations. Further analyses evaluated the influence of cutting speeds and contact friction coefficients over the chip flow stress, equivalent plastic strain, and chip morphology. The methodology developed can be implemented in resolving the industrial problems in the biomedical sector for predicting the chip morphology of the Ti6Al4V alloy, fracture mechanisms of hard-to-cut materials, and the effects of different cutting parameters on workpiece integrity.     

Acute promyelocytic leukaemia is characterized by stable incidence and improved survival that is restricted to patients managed in leukaemia referral centres: a pan‐Canadian epidemiological study

Timely diagnosis and care are major determinants of the outcome in acute promyelocytic leukaemia (APL), a malignancy whose incidence may be increasing. The Canadian Cancer Registry (CCR) and health system represent valuable settings to study APL epidemiology. We analysed the CCR, which contains data on all Canadians with APL. To provide clinical information lacking in the CCR, we obtained data from five leukaemia referral centres during a similar time period. Between 1993 and 2007, there were 399 APL in Canada. Age‐standardized incidence was 0·083/100 000 and was stable over time. The early death (ED) rate was 21·8% (10·6% in patients <50 years old and 35·5% for those aged >50 years), with no improvement over time. Five‐year overall survival (OS) was 54·6% (73·3% in patients <50 years; 29·1% older patients). In the referral cohort, 131 patients were diagnosed between 1999 and 2010. ED was 14·6% and 2‐year OS was 76·5%. Within this cohort, ED and OS improved over time, although advanced patient age remained an adverse determinant of OS. In Canada, APL incidence is unexpectedly low and temporally stable. ED was higher than reported in clinical trials, but similar to reports from other registries. In contrast, ED was lower in referral centres and improved with time.     

WWOX,the common fragile site FRA16D gene product,regulates ATM activation and the DNA damage response

Genomic instability is a hallmark of cancer. The WW domain-containing oxidoreductase (WWOX) is a tumor suppressor spanning the common chromosomal fragile site FRA16D. Here, we report a direct role of WWOX in DNA damage response (DDR) and DNA repair. We show that Wwox deficiency results in reduced activation of the ataxia telangiectasia-mutated (ATM) checkpoint kinase, inefficient induction and maintenance of γ-H2AX foci, and impaired DNA repair. Mechanistically, we show that, upon DNA damage, WWOX accumulates in the cell nucleus, where it interacts with ATM and enhances its activation. Nuclear accumulation of WWOX is regulated by its K63-linked ubiquitination at lysine residue 274, which is mediated by the E3 ubiquitin ligase ITCH. These findings identify a novel role for the tumor suppressor WWOX and show that loss of WWOX expression may drive genomic instability and provide an advantage for clonal expansion of neoplastic cells.Genomic instability is a common characteristic of human cancers. The DNA damage response (DDR) maintains the integrity of the genome in response to DNA damage. DDR is a complex signaling process that results in cell cycle arrest followed by either DNA repair or apoptosis if the DNA damage is too extensive to be repaired (1–3). Key mammalian damage response sensors are ataxia telangiectasia-mutated (ATM), ATM and Rad3-related, and DNA-dependent PKs (4, 5). Disruption of the DDR machinery in human cells leads to genomic instability and an increased risk of cancer progression (6, 7).The WW domain-containing oxidoreductase (WWOX) gene spans the common fragile site (CFS) FRA16D (8, 9). Genomic alterations affecting the WWOX locus have been reported in several types of cancer and include homozygous and hemizygous deletions (10–13). Ectopic expression of WWOX in WWOX-negative cancer cells attenuates cell growth and suppresses tumor growth in immunocompromised mice (10, 11, 14). Importantly, targeted ablation of Wwox in mice results in higher incidence of spontaneous lesions resembling osteosarcomas and lung and mammary tumors (14–16). These findings suggest WWOX as a tumor suppressor. The WWOX protein contains two N-terminal WW domains mediating WWOX interaction with PP(proline)x(amino acid)Y(tyrosine)-containing proteins (11, 17) and a central short-chain deyhdrogenase/reductase domain that has been proposed to function in steroidogenesis (18). Recent characterization of WWOX domains revealed that they interact, mainly through the WW1 domain, with multiprotein networks (3). The mechanism by which WWOX suppresses tumorigenicity is, however, not well-known.In vitro, CFSs are defined as gaps or breaks on metaphase chromosomes that occur in cells treated with inhibitors of DNA replication (19, 20). In vivo, CFSs are preferential targets of replication stress in preneoplastic lesions (21), and emerging evidence suggests that they represent early warning sensors for DNA damage (22–24). Both genetic and epigenetic factors are thought to regulate the fragility of CFS (25, 26). Recent profiling studies of CFS provide evidence that the functional fragility of CFS is tissue-specific (27–29). High-throughput genomic analyses of 3,131 cancer specimens (12) and 746 cancer cell lines (13) have recently identified large deletions in CFSs, including the FRA16D/WWOX locus. Although these deletions have been linked to the presence of DNA replication stress (30), the molecular function of gene products of CFSs, including the WWOX protein, is poorly understood. Here, we identify a direct role of WWOX in the DDR and show that the WWOX gene product functions as a modulator of the DNA damage checkpoint kinase ATM.