CHK1 overexpression in T-cell acute lymphoblastic leukemia is essential for proliferation and survival by preventing excessive replication stress

Checkpoint kinase 1 (CHK1) is a key component of the ATR (ataxia telangiectasia-mutated and Rad3-related)-dependent DNA damage response pathway that protect cells from replication stress, a cell intrinsic phenomenon enhanced by oncogenic transformation. Here, we show that CHK1 is overexpressed and hyperactivated in T-cell acute lymphoblastic leukemia (T-ALL). CHEK1 mRNA is highly abundant in patients of the proliferative T-ALL subgroup and leukemia cells exhibit constitutively elevated levels of the replication stress marker phospho-RPA32 and the DNA damage marker γH2AX. Importantly, pharmacologic inhibition of CHK1 using PF-004777736 or CHK1 short hairpin RNA-mediated silencing impairs T-ALL cell proliferation and viability. CHK1 inactivation results in the accumulation of cells with incompletely replicated DNA, ensuing DNA damage, ATM/CHK2 activation and subsequent ATM- and caspase-3-dependent apoptosis. In contrast to normal thymocytes, primary T-ALL cells are sensitive to therapeutic doses of PF-004777736, even in the presence of stromal or interleukin-7 survival signals. Moreover, CHK1 inhibition significantly delays in vivo growth of xenotransplanted T-ALL tumors. We conclude that CHK1 is critical for T-ALL proliferation and viability by downmodulating replication stress and preventing ATM/caspase-3-dependent cell death. Pharmacologic inhibition of CHK1 may be a promising therapeutic alternative for T-ALL treatment.

Requirement for the cell division protein DivIB in polar cell division and engulfment during sporulation in Bacillus subtilis

During spore formation in Bacillus subtilis, cell division occurs at the cell pole and is believed to require essentially the same division machinery as vegetative division. Intriguingly, although the cell division protein DivIB is not required for vegetative division at low temperatures, it is essential for efficient sporulation under these conditions. We show here that at low temperatures in the absence of DivIB, formation of the polar septum during sporulation is delayed and less efficient. Furthermore, the polar septa that are complete are abnormally thick, containing more peptidoglycan than a normal polar septum. These results show that DivIB is specifically required for the efficient and correct formation of a polar septum. This suggests that DivIB is required for the modification of sporulation septal peptidoglycan, raising the possibility that DivIB either regulates hydrolysis of polar septal peptidoglycan or is a hydrolase itself. We also show that, despite the significant number of completed polar septa that form in this mutant, it is unable to undergo engulfment. Instead, hydrolysis of the peptidoglycan within the polar septum, which occurs during the early stages of engulfment, is incomplete, producing a similar phenotype to that of mutants defective in the production of sporulation-specific septal peptidoglycan hydrolases. We propose a role for DivIB in sporulation-specific peptidoglycan remodelling or its regulation during polar septation and engulfment.

Laparoscopic versus open splenectomy: a comparative study

Laparoscopic splenectomy (LS) is gaining wide acceptance as a safe, effective alternative to open splenectomy (OS) in the treatment of hematologic disorders in adult and pediatric patients, with low conversion rates and complications. The aim of this retrospective case-control study was to compare two cohorts of patients, with similar characteristics, who underwent OS or LS in a single institution. The medical records of the initial 20 consecutive patients who underwent LS were reviewed and compared with a control group of 28 patients undergoing OS, matched for age, gender, diagnosis, splenic size and weight, and American Society of Anesthesiologists score. Data were collected regarding operative time, blood loss, blood transfusions, pathologic findings, accessory spleen detection, complications, ileus duration, and postoperative hospital stay. Nineteen patients underwent attempted LS. One procedure (5%) was converted to OS for uncontrolled hilar bleeding. Accessory spleens were detected in two cases in the LS group compared with four cases in the OS group (14%). Mean operative time was 165 minutes (range: 100-240 minutes) for LS and 114 minutes (75-180 minutes) for OS (P < 0.001). In the LS group a regular diet was tolerated 36 hours (range: 24-48 hours) after surgery compared with 72 hours (range: 48-96 hours) for the OS group (P < 0.001), and mean postoperative hospital stay was 4.1 days (range: 3-8 days) for LS, compared with 8.1 days (range: 5-12 days) for OS (P < 0.001). No differences were observed in blood loss, complication rates, or transfusion requirements. Compared with OS, LS requires more operative time (showing a learning curve), is comparable in blood loss, transfusion requirements, complication rates, and detection of accessory spleens and appears to be superior in terms of return of bowel function and hospital stay.

[The use of the biofragmentable ring (BAR-Valtrac) in colon surgery]

BACKGROUND

Clinical results of colic anastomosis using biofragmentable anastomosis ring (BAR-Valtrac) are presented. Such a method showed to be a real alternative technique to the usual ones.

METHODS

Eighty-six colic anastomosis using BAR are collected, 76 of which performed as elective surgery and 10 in emergency. The patients were 47 males and 39 females, with a mean age of 64 years. In 63 cases the patients were affected by colic neoplastic disease, in 16 by complicated diverticular disease (stenosis or perforation) and 7 patients had neoplastic disease of other organs involving the colon BAR device was used in 48 colic reconstructions after segmentary resection and in 38 colic reconstructions after left hemicolectomy. In each case 31-34 mm BAR were used.

RESULTS

No perioperative death occurred in our series. Only one case (2%) of anastomotic leak was observed, while in 3 cases (4%) intestinal canalization disorders occurred. No problems for ring expulsion occurred in any patient. Three late complications were observed, as three cases of asymptomatic substenosis discovered during instrumental follow-up and spontaneously cleared up.

CONCLUSIONS

On the basis of clinical results, and according to those reported in literature BAR anastomosis is considered a safe, feasible and easy technique to perform colic anastomosis, even in emergency, limited to the intraperitoneal tract of the colon.

The amino-terminal domain of the CCR2 chemokine receptor acts as coreceptor for HIV-1 infection

The chemokines are a homologous serum protein family characterized by their ability to induce activation of integrin adhesion molecules and leukocyte migration. Chemokines interact with their receptors, which are composed of a single-chain, seven-helix, membrane-spanning protein coupled to G proteins. Two CC chemokine receptors, CCR3 and CCR5, as well as the CXCR4 chemokine receptor, have been shown necessary for infection by several HIV-1 virus isolates. We studied the effect of the chemokine monocyte chemoattractant protein 1 (MCP-1) and of a panel of MCP-1 receptor (CCR2)-specific monoclonal antibodies (mAb) on the suppression of HIV-1 replication in peripheral blood mononuclear cells. We have compelling evidence that MCP-1 has potent HIV-1 suppressive activity when HIV-1-infected peripheral blood lymphocytes are used as target cells. Furthermore, mAb specific for the MCP-1R CCR2 which recognize the third extracellular CCR2 domain inhibit all MCP-1 activity and also block MCP-1 suppressive activity. Finally, a set of mAb specific for the CCR2 amino-terminal domain, one of which mimics MCP-1 activity, has a potent suppressive effect on HIV-1 replication in M- and T-tropic HIV-1 viral isolates. We conjecture a role for CCR2 as a coreceptor for HIV-1 infection and map the HIV-1 binding site to the amino-terminal part of this receptor. This concurs with results showing that the CCR5 amino terminus is relevant in HIV-1 infection, although chimeric fusion of various extracellular domains shows that other domains are also implicated. We discuss the importance of CCR2 structure relative to its coreceptor role and the role of anti-CCR2 receptor antibodies in the prevention of HIV-1 infection.

Relation between Surgery-Induced Prolactin Increase and the Menstrual Cycle Phase at Time of Surgery in Premenopausal Breast Cancer

It has been suggested that both the menstrual cycle phase and postoperative changes in prolactin (PRL) secretion at the time of surgery may influence the prognosis of breast cancer. The present study was carried out to evaluate the relation between menstrual cycle period and surgery-induced PRL variations. We evaluated 32 premenopausal women with operable breast carcinoma; 17 were in perimenstrual phase (days 1-6 and 21-28) and 15 were in the mid-cycle (days 7-20) period at’ the time of surgery. To investigate serum levels of PRL, venous blood samples were collected before and 7 days after surgery. Postoperative hyperprolactinemia occurred in 17/32 patients and it was statistically more frequent in patients surgically treated during the perimenstrual phase than in the mid-cycle phase (12/17 vs 5/15; p < 0.05), while no other parameter (including axillary node and estrogen receptor status) showed a significant influence on hyperprolactinemia rate. The results suggest that in premenopausal breast cancer patients surgery-induced hyperprolactinemia may be influenced by the menstrual cycle phase at the time of surgery.