title: Enhanced survival in perineural invasion of pancreatic cancer: an in vitro approach.
abstract: Pancreatic cancer (PanCa) is characterized by perineural invasion (PNI), early lymph node and liver metastasis, and poor prognosis. PNI is one of the important causes of local recurrence. Little is known about the mechanism of PNI in PanCa. We presented a novel model system that may shed light on the mystery of PNI in PanCa. In this study, mouse dorsal root ganglia (DRGs) and human PanCa cell line (MIA PaCa-2) were cocultured in Matrigel matrix (BD Biosciences, San Jose, CA) to build this PNI model. MIA PaCa-2 cell line alone (control 1) or DRG alone (control 2) was cultured with Matrigel matrix as controls. Neurite outgrowth, cell colony growth, neurite-colony contact, and retrograde extension were observed under inverted microscopy and then were photographed and quantitated with the Optimas imaging system (Optimas Corp., Bothell, MA). At day 14, both the experimental and control 2 samples were harvested and subjected to total RNA isolation and fixed in paraffin-embedded blocks. Slides cut from paraffin blocks were studied with Ki-67 immunostaining and TUNEL assay. Gene profiling was performed using complementary DNA microarray. Overexpressed target genes were verified by quantitative reverse transcriptase polymerase chain reaction. The results showed that reciprocity was observed between neurites and MIA PaCa colonies with 24 hours of coculture. Neurite outgrowth was stimulated in the presence of pancreatic carcinoma cells, which showed 2-fold more area than did control 2. After 72 hours, MIA PaCa colonies cocultured with DRG exhibited 58% more colony area than did control 1. The Ki-67 index of the DRG/MIA PaCa cells (mean, 5.02%) was significantly higher than that in control 1 (mean, 1.18%) (P < .05); in contrast, the apoptotic index in the DRG/MIA PaCa cells was significantly lower (mean, 0.45%) than that in the control 1 (mean, 1.85%) (P < .001). Prosurvival genes MALT1 and TRAF were increased 2-fold in DRG/MIA PaCa compared with controls. We demonstrated that neural-epithelial interaction is a mutually beneficial process for the growth of nerves and PanCa cells. It is possible that oncogenes and growth factors might act synergistically in promoting proliferation and/or inhibiting apoptosis, a survival strategy crucial to the development of PNI in PanCa.
authors.affiliation: Department of Pathology, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Hong
authors.initials: H
authors.lastname: Dai
authors.forename: Rile
authors.initials: R
authors.lastname: Li
authors.forename: Thomas
authors.initials: T
authors.lastname: Wheeler
authors.forename: Mustafa
authors.initials: M
authors.lastname: Ozen
authors.forename: Michael
authors.initials: M
authors.lastname: Ittmann
authors.forename: Marcus
authors.initials: M
authors.lastname: Anderson
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.forename: David
authors.initials: D
authors.lastname: Rowley
authors.forename: Mamoun
authors.initials: M
authors.lastname: Younes
authors.forename: Gustavo E
authors.initials: GE
authors.lastname: Ayala
mesh_terms: D000818:Animals; D017209:Apoptosis; D020169:Caspases / Q000235:genetics; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002470:Cell Survival; D018920:Coculture Techniques; D005727:Ganglia, Spinal / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D020869:Gene Expression Profiling; D006801:Humans; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D019394:Ki-67 Antigen / Q000032:analysis; D051379:Mice; D000074884:Mucosa-Associated Lymphoid Tissue Lymphoma Translocation 1 Protein; D009363:Neoplasm Proteins / Q000235:genetics; D016501:Neurites / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D010190:Pancreatic Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D047988:Tumor Necrosis Factor Receptor-Associated Peptides and Proteins / Q000235:genetics
chemical_list: D019394:Ki-67 Antigen; D009363:Neoplasm Proteins; D047988:Tumor Necrosis Factor Receptor-Associated Peptides and Proteins; D007041:Hypoxanthine Phosphoribosyltransferase; D020169:Caspases; C400109:MALT1 protein, human; D000074884:Mucosa-Associated Lymphoid Tissue Lymphoma Translocation 1 Protein