Molecular mechanism(s) of actinomycin-D induced sensitization of pancreatic cancer cells to CD95 mediated apoptosis.

The death receptor CD95 transduces apoptotic death signaling in many cell types. However, in pancreatic tumor cells CD95 mediated apoptotic machinery is blocked by unknown protein(s). We and others have recently demonstrated that actinomycin-D (ActD) treatment induces sensitization of pancreatic cancer cells as well as other cell types to CD95 mediated apoptosis. In addition, NF-kappaB/Akt system has been implicated in the processes of CD95 mediated apoptosis, however the precise mechanism by which ActD sensitizes pancreatic tumor cells to CD95 mediated apoptosis is still unknown. In the present study, we demonstrated that HPAC and PANC1 pancreatic cancer cells constitutively express high levels of NF-kappaB and phosphorylated form of Akt. ActD at a dose that is known to sensitize pancreatic cancer cells to CD95 mediated apoptosis abrogated the DNA binding activity of NF-kappaB but did not affect expression of phosphorylated Akt. Co-treatment of pancreatic cancer cells with ActD and agonist anti-CD95 antibodies showed no effect on the abrogation on the DNA binding activity of NF-kappaB, but decreased the expression of phosphorylated Akt. Moreover, treatment with PI3-kinase inhibitor LY294002 did not show any sensitization of pancreatic cancer cells to CD95 mediated apoptosis. Our data suggest that ActD sensitizes pancreatic cancer cells to CD95 mediated apoptosis through the abrogation of DNA binding activity of NF-kappaB, rather than PI3-kinase/Akt system. Over-expression of phosphorylated Akt in pancreatic cancer cells is controlled by effective apoptotic signaling from CD95 receptors, but do not protect tumor cells from CD95 induced apoptosis. Thus, our results indicate that modulation of NF-kappaB activity rather then Akt may provide a useful tool to sensitize pancreatic cancer cells to CD95 mediated apoptosis.

Clinicopathologic analysis of pancreatic adenocarcinoma in African Americans and Caucasians.

INTRODUCTION: African Americans have a higher incidence of pancreatic adenocarcinoma than do Caucasians for unknown reasons. Whether other clinicopathologic differences exist between these two groups is not known. This study was undertaken to compare the clinical, pathologic, and biologic findings for a group of patients with a histologic diagnosis of pancreatic ductal adenocarcinoma of the usual type in a single institution. METHODOLOGY: We studied 410 patients (166 African Americans and 244 Caucasians) with a histologic diagnosis of pancreatic ductal adenocarcinoma of the usual type and analyzed (a) the clinicopathologic characteristics of the tumors, (b) the immunohistochemical expression of biomarkers implicated in pancreatic carcinogenesis (Fas, Fas ligand, HER2, p21/waf-1, p27, and p53), and (c) the presence and types of K- mutations at codon 12 as determined by polymerase chain reaction-mediated amplification. All elements of data were not available for all patients. RESULTS: African Americans had significantly higher rates of K-ras mutations to valine than did Caucasians (58% versus 22%, respectively; p = 0.015) and were less likely to have received chemotherapy (45% versus 70%, respectively; p = 0.001) or radiation therapy (34% versus 57%, respectively; p = 0.003). African Americans also had more frequent positive surgical margins than did Caucasians (56% versus 25%, respectively; p = 0.001), although mean tumor size was similar between the two groups (African Americans, 3.4 cm; Caucasians, 3.5 cm). Other clinicopathologic variables were similar between the two groups, including median survival (African Americans, 8.5 months; Caucasians, 10.1 months), 5-year survival (African Americans, 3%; Caucasians, 6%), and stage at presentation. Differences in biomarker immunoreactivity included less frequent Fas expression (4% versus 24%, respectively; p = 0.048) and a trend toward more frequent strong HER2 expression (39% versus 18%, respectively p = 0.11) in African Americans than in Caucasians. CONCLUSION: Although African American and Caucasian patients had similar survival rates associated with usual type pancreatic ductal adenocarcinoma, there were differences in management and expression of biologic markers between these two groups. African Americans were significantly less likely to receive radiation therapy or chemotherapy than were Caucasians, which may assume more importance as treatment improves. At the molecular level, African Americans had more frequent K- mutations to valine than did Caucasians.

Chemoradiotherapy in the treatment of regional pancreatic carcinoma: a phase II study.

In locally advanced pancreatic cancer, the utilization of chemotherapy and radiotherapy is increasing, although in view of the reported long-term results of several contemporary trials, further improvements are certainly needed. Encouraging results using the combination of cisplatin, cytarabine, caffeine, and continuous infusion (CI) 5-fluorouracil (5-FU) (PACE) for the treatment of advanced pancreatic carcinoma prompted a phase II study using PACE followed by external beam radiotherapy with CI of 5-FU (PACE-RT) for localized disease. Forty-one patients were treated with PACE-RT as adjuvant therapy after surgical resection (21 patients), or as primary therapy for locally advanced, unresectable disease (20 patients), with reevaluation for resection after completion of treatment. PACE consisted of cisplatin 100 mg/m2 IV on day 1, cytarabine 2 g/m2 IV every 12 hours x 2 doses, and caffeine 400 mg/m2 subcutaneously after each cytarabine dose; and days 3 to 21, 5-FU 250 mg/m2/d given by CI. Cycles were repeated every 28 days. After 2 cycles of PACE, radiation therapy was given concurrently with 5-FU at 200 mg/m2/d. In the adjuvant setting, the tumor bed and the draining lymph node basin received 50.4 Gy and 45 Gy, respectively. In the neoadjuvant setting, the primary and regional lymph nodes were to receive 39.6 Gy followed by a neutron boost of 8 NGy to the gross tumor volume. Photon therapy was delivered at 1.8 Gy per fraction and neutron therapy at 0.8 NGy per fraction, 5 days a week. All patients were evaluable for toxicity and survival. The most common toxicity was myelosuppression, with grade III to IV neutropenia occurring in 59% of the patients. The median survival times in the locally advanced and adjuvant patients were 13.4 and 18.1 months, with 1-year survival rates of 52% and 65%, respectively. Nine of 20 patients receiving PACE-RT for unresectable carcinoma had sufficient tumor regression to meet clinical criteria for exploration; three were resected with curative intent. The survival of these three patients undergoing resection after neo-adjuvant therapy was 22.4, 24.3 and 40 months. The treatment program was active, but only moderately well tolerated. Modification of this regimen with newer, less toxic drugs may provide better results and reduced toxicity.