Structural characterization and biological implications of sulfated N-glycans in a serine protease from the neotropical moth Hylesia metabus (Cramer [1775]) (Lepidoptera: Saturniidae).

Contact with the urticating setae from the abdomen of adult females of the neo-tropical moth Hylesia metabus gives rise to an urticating dermatitis, characterized by intense pruritus, generalized malaise and occasionally ocular lesions (lepidopterism). The setae contain a pro-inflammatory glycosylated protease homologous to other S1A serine proteases of insects. Deglycosylation with PNGase F in the presence of a buffer prepared with 40% H2 (18)O allowed the assignment of an N-glycosylation site. Five main paucimannosidic N-glycans were identified, three of which were exclusively α(1-6)-fucosylated at the proximal GlcNAc. A considerable portion of these N-glycans are anionic species sulfated on either the 4- or the 6-position of the α(1-6)-mannose residue of the core. The application of chemically and enzymatically modified variants of the toxin in an animal model in guinea pigs showed that the pro-inflammatory and immunological reactions, e.g. disseminated fibrin deposition and activation of neutrophils, are due to the presence of sulfate-linked groups and not on disulfide bonds, as demonstrated by the reduction and S-alkylation of the toxin. On the other hand, the hemorrhagic vascular lesions observed are attributed to the proteolytic activity of the toxin. Thus, N-glycan sulfation may constitute a defense mechanism against predators.

Ceramide regulates gemcitabine-induced senescence and apoptosis in human pancreatic cancer cell lines.

Bioactive sphingolipids are potent intracellular signaling molecules having profound effects on cell death, growth, and differentiation. Pharmacologic manipulation of sphingolipid levels could have a significant effect on the induction of apoptosis by anticancer agents, and thus, improve treatment efficacy. We observed that gemcitabine cannot completely kill AsPc1 and Panc1 human pancreatic cancer cells in culture; even at high concentrations of gemcitabine, 30% to 40% of the cells remain viable. By adding sphingomyelin to the culture medium, gemcitabine-induced cell death increased synergistically to >90%. Panc1 cells that survived high concentrations of gemcitabine had an increase in beta-galactosidase activity, a marker of senescence. The inclusion of sphingomyelin with gemcitabine reduced beta-galactosidase activity, as compared with cells treated with gemcitabine alone. Expression of p21(waf1/cip1) in both cell lines exposed to sphingomyelin, gemcitabine, and gemcitabine + sphingomyelin varied relative to the untreated group. C(8)-ceramide induced both cell death and senescence in a dose-dependent manner. These results indicate that gemcitabine induces senescence in pancreatic cancer cells and that sphingomyelin-enhanced chemosensitivity is achieved through reducing the induction of senescence by redirecting the cell to enter the apoptotic pathway. Ceramide levels seem to be critical to this decision, with cell cycle progression being uninhibited at low ceramide levels, senescence induced at moderate levels, and apoptosis initiated at high levels. Our results provide further evidence that targeting the sphingolipid metabolism is a means of enhancing the efficacy of chemotherapeutic agents.

Expression patterns of CEACAM5 and CEACAM6 in primary and metastatic cancers.

BACKGROUND: Many breast, pancreatic, colonic and non-small-cell lung carcinoma lines express CEACAM6 (NCA-90) and CEACAM5 (carcinoembryonic antigen, CEA), and antibodies to both can affect tumor cell growth in vitro and in vivo. Here, we compare both antigens as a function of histological phenotype in breast, pancreatic, lung, ovarian, and prostatic cancers, including patient-matched normal, primary tumor, and metastatic breast and colonic cancer specimens. METHODS: Antigen expression was determined by immunohistochemistry (IHC) using tissue microarrays with MN-15 and MN-3 antibodies targeting the A1B1- and N-domains of CEACAM6, respectively, and the MN-14 antibody targeting the A3B3 domain of CEACAM5. IHC was performed using avidin-biotin-diaminobenzide staining. The average score +/- SD (0 = negative/8 = highest) for each histotype was recorded. RESULTS: For all tumors, the amount of CEACAM6 expressed was greater than that of CEACAM5, and reflected tumor histotype. In breast tumors, CEACAM6 was highest in papillary > infiltrating ductal > lobular > phyllodes; in pancreatic tumors, moderately-differentiated > well-differentiated > poorly-differentiated tumors; mucinous ovarian adenocarcinomas had almost 3-fold more CEACAM6 than serous ovarian adenocarcinomas; lung adenocarcinomas > squamous tumors; and liver metastases of colonic carcinoma > primary tumors = lymph nodes metastases > normal intestine. However, CEACAM6 expression was similar in prostate cancer and normal tissues. The amount of CEACAM6 in metastatic colon tumors found in liver was higher than in many primary colon tumors. In contrast, CEACAM6 immunostaining of lymph node metastases from breast, colon, or lung tumors was similar to the primary tumor. CONCLUSION: CEACAM6 expression is elevated in many solid tumors, but variable as a function of histotype. Based on previous work demonstrating a role for CEACAM6 in tumor cell migration, invasion and adhesion, and formation of distant metastases (Blumenthal et al., Cancer Res 65: 8809-8817, 2005), it may be a promising target for antibody-based therapy.

Modulation of marrow proliferation and chemosensitivity by tumor-produced cytokines from syngeneic pancreatic tumor lines.

PURPOSE: A dynamic process exists in which hematopoietic progenitor andstromal cells interact to maintain normal hematopoiesis or to adjust to hematopoietic needs under "stress" situations. The effect that tumor-produced growth factors have on hematopoiesis has not been addressed. We postulate that an excess of tumor-produced stimulatory or inhibitory cytokines could impact marrow proliferation and sensitivity to cytotoxic agents. METHODS: We used two tumor lines (TGP47 and TGP51) taken from a panel of syngeneic murine pancreatic carcinomas, in which each produces a unique array of cytokines, and evaluated their effect in vitro on marrow proliferation and chemosensitivity. RESULTS: TGP51- and TGP47-conditioned medium increased [3H]thymidine incorporation into cultured marrow cells by approximately 12-fold and 4.8-fold, respectively. The percent of cells in the S + G2-M phases of the cell cycle increased by 110% (TGP51) and 44% (TGP47), and the MCF for proliferating cell nuclear antigen expression increased by 104% (TGP51) and 45% (TGP47). Marrow proliferation of untreated cells could be reduced by interleukin 6 but not by granulocyte macrophage colony-stimulating factor neutralization. Conditioned medium-induced stimulation was unchanged by either interleukin 6alpha or granulocyte macrophage colony-stimulating factor alpha. FLT3-Lalpha reduced marrow proliferation induced by TGP51 medium. Addition of FLT3-L to TGP47 medium additionally enhanced the marrow proliferation. Antitumor necrosis factor alpha additionally increased marrow proliferation induced by TGP47 and TGP51 conditioned medium, whereas addition of tumor necrosis factor alpha reduced marrow proliferation associated with TGP51 medium. The TGP51-induced increase in marrow proliferation resulted in increased marrow chemosensitivity to three myelosuppressive drugs: doxorubicin, cyclophosphamide, and CPT-11, decreasing the IC50 by 46%, 38%, and 95%, respectively. CONCLUSION: Tumor-produced cytokines can affect marrow proliferative activity and, thus, chemosensitivity to three distinct classes of chemotherapeutics.