Jodi M. Coates

Arginine Deiminase as a Novel Therapy for Prostate Cancer Induces Autophagy and Caspase-Independent Apoptosis

Arginine deprivation as an anticancer therapy has historically been met with limited success. The development of pegylated arginine deiminase (ADI-PEG20) has renewed interest in arginine deprivation for the treatment of some cancers. The efficacy of ADI-PEG20 is directly correlated with argininosuccinate synthetase (ASS) deficiency. CWR22Rv1 prostate cancer cells do not express ASS, the rate-limiting enzyme in arginine synthesis, and are susceptible to ADI-PEG20 in vitro. Interestingly, apoptosis by 0.3 microg/mL ADI-PEG20 occurs 96 hours posttreatment and is caspase independent. The effect of ADI-PEG20 in vivo reveals reduced tumor activity by micropositron emission tomography as well as reduced tumor growth as a monotherapy and in combination with docetaxel against CWR22Rv1 mouse xenografts. In addition, we show autophagy is induced by single amino acid depletion by ADI-PEG20. Here, autophagy is an early event that is detected within 1 to 4 hours of 0.3 microg/mL ADI-PEG20 treatment and is an initial protective response to ADI-PEG20 in CWR22Rv1 cells. Significantly, the inhibition of autophagy by chloroquine and Beclin1 siRNA knockdown enhances and accelerates ADI-PEG20-induced cell death. PC3 cells, which express reduced ASS, also undergo autophagy and are responsive to autophagy inhibition and ADI-PEG20 treatment. In contrast, LNCaP cells highly express ASS and are therefore resistant to both ADI-PEG20 and autophagic inhibition. These data point to an interrelationship among ASS deficiency, autophagy, and cell death by ADI-PEG20. Finally, a tissue microarray of 88 prostate tumor samples lacked expression of ASS, indicating ADI-PEG20 is a potential novel therapy for the treatment of prostate cancer

Negligible Effect of Selective Preoperative Biliary Drainage on Perioperative Resuscitation, Morbidity, and Mortality in Patients Undergoing Pancreaticoduodenectomy

OBJECTIVE To examine the effect of selective preoperative biliary drainage (BD) on perioperative resuscitation, morbidity, and mortality in patients undergoing pancreaticoduodenectomy. Biliary drainage prior to pancreaticoduodenectomy remains controversial. Proponents argue that it facilitates referral to high-volume tertiary centers, while detractors maintain that it increases surgical morbidity and mortality. DESIGN Retrospective analysis of single-institution tumor registry database. SETTING University medical center. PATIENTS From October 1, 2003, to May 31, 2008, 90 patients underwent pancreaticoduodenectomy for periampullary mass lesions. MAIN OUTCOME MEASURES Clinicopathologic data were reviewed and analyzed among patients who did and did not receive BD for their association with perioperative outcomes. chi(2) Analysis, independent-samples t tests, and Mann-Whitney U tests were used as appropriate. RESULTS Fifty-six patients (62%) underwent BD, and 34 (38%) did not. Intraoperative bile cultures were positive for 1 or more species of microorganisms in 88% of stented patients (35 of 40). There were no significant differences in fluid requirements, transfusion requirements, or surgery duration between patients who did and did not undergo BD. Estimated blood loss was increased in patients who received BD (625 mL vs 525 mL in patients who did not undergo BD; P = .03), while reoperation was significantly more common in nonstented patients (4% vs 15% in patients who did not undergo BD; P = .02). Intensive care unit stay, overall length of stay, pancreatic leak/abscess/fistula, infectious complications, postoperative percutaneous drainage, hospital readmission, and 30- and 90-day mortality were not significantly different between the 2 groups. CONCLUSIONS Although preoperative biliary stents may complicate the intraoperative management and lessen the postoperative complications of patients undergoing pancreaticoduodenectomy, only estimated blood loss and reoperation were significantly different in this cohort. Further study may reveal patient subgroups who may specifically benefit or suffer from preoperative biliary stenting. Currently, selective preoperative BD appears appropriate in the multidisciplinary management of patients with periampullary lesions.

Cancer Therapy Beyond Apoptosis: Autophagy and Anoikis as Mechanisms of Cell Death

Apoptosis has long been recognized as a critical mechanism of programmed cell death that is preserved among all eukaryotes and is involved in a variety of disease processes. Malignant transformation of cells is associated with a constellation of pro-survival mutations rendering them resistant to apoptosis. Traditional cancer therapy evokes cell death by inducing apoptosis; however, the apoptotic resistance inherent in cancer cells has been a significant barrier to effective chemotherapy. More recently, other mechanisms of cell death have emerged as potential novel mechanisms for cancer therapies to induce cell death, either in addition to, or instead of, apoptosis-induced cytotoxic treatment. Autophagy is a process that occurs in all cells, but is induced in many types of cancer. Autophagy functions as both a cell survival and a cell death mechanism depending on the context and the stimuli, which are likely exploitable for cancer therapy. Anoikis is also a physiologic process in normal cells used to maintain homeostasis, in which cell death is induced in response to loss of extracellular membrane (ECM) attachment. Cancer cells are notoriously resistant to anoikis, enabling metastasis and new tumor growth beyond their original environment. Interestingly, autophagy may actually by a major contributor to anoikis resistance in cancer. As these two processes are elucidated in more detail, there is great potential for novel targets that affect cancer cell death, in addition to the current cytotoxic agents.

Adjuvant radiation therapy is associated with improved survival for adenoid cystic carcinoma of the breast

The role of adjuvant radiation therapy (RT) for adenoid cystic carcinoma (ACC) of the breast remains unclear.

Targeting Bcl-2-Mediated Cell Death as a Novel Therapy in Pancreatic Cancer

BACKGROUND Bcl-2 is an essential regulator of programmed cell death (PCD). Overexpression of Bcl-2 is common in pancreatic cancer; the high levels have been shown to correlate with resistance to PCD. This resistance is mediated by binding of Bcl-2 via its BH-3 domain to diverse proteins, including the Bax/Bak family members, various protein kinases, and beclin 1, which are involved in regulation of autophagy (type II PCD). Small molecule inhibitors of BH-3-mediated binding of Bcl-2 have been recently developed, although no investigation has been conducted in pancreatic cancer, a malignancy characterized by extreme resistance to PCD. METHODS The effect of the Bcl-2 binding inhibitor A-779024 on PCD was assessed by fluorescence activated cell sorting; the effect on Bcl-2 and other PCD-related proteins was analyzed by immunoblotting. Induction of autophagy was determined by fluorescence microscopy using a stably transfected GFP-LC3 construct to visualize autophagosome formation. Co-localization of Bcl-2 with binding partners regulating PCD was examined by immunoprecipitation and confocal immunofluorescent microscopy. RESULTS A-779024 induced PCD in a dose- and time-dependent fashion. No change was seen in the protein levels of Bcl-2, Bax, Bcl-XL, or Mcl-1. Contrary to prediction, A-779024 was ineffective at inducing autophagy in these cells. Co-localization studies demonstrated that Bcl-2 was not bound to beclin 1 and, therefore, treatment with A-779024 could not induce release of beclin 1 and initiation of autophagy. CONCLUSIONS Disruption of Bcl-2 activity using the small molecule inhibitor A-779024 induces apoptotic but not autophagic PCD. This approach may be a novel therapy, either alone or in combination with other treatments such as chemotherapy or autophagy modulating agents in pancreatic cancer.