We established a pancreatic adenocarcinoma cell line (CFPAC-1) from a patient with cystic fibrosis (CF) and assessed some of its properties. The cells show epithelial morphology and express cytokeratin and oncofetal antigens characteristic of pancreatic duct cells. Basal and stimulated levels of cAMP and cAMP-dependent protein kinase and the biophysical properties of single Cl-channels in CFPAC-1 are similar to those of airway and sweat gland primary cultures and Cl--secreting epithelial cell lines. Anion transport and single Cl-channel activity was stimulated by Ca2+ ionophores but not by forskolin, cAMP analogs, or phosphodiesterase inhibitors. The cells express the CF gene and manifest the most common CF mutation, deletion of three nucleotides resulting in a phenylalanine-508 deletion. These properties have been stable through >80 passages (24 months), suggesting that CFPAC-1 can serve as a continuous cell line that displays the CF defect.
Cystic fibrosis (CF) is a genetic disease characterized by abnormal regulation of epithelial cell chloride channels. Nonepithelial cells, including lymphocytes and fibroblasts, may exhibit a similar defect. Two independent techniques were used to assess the macroscopic chloride permeability (PCl) of freshly isolated B lymphocytes and of B and T lymphocyte cell lines. Values for PCl increased specifically during the G1 phase of the cell cycle and could be further enhanced by increasing intracellular adenosine 3',5'-monophosphate (cAMP) or calcium. In lymphocytes from CF patients, regulation of PCl during the cell cycle and by second messengers was absent. Characterization of the cell cycle-dependent expression of the chloride permeability defect in lymphocytes from CF patients increases the utility of these cells in the analysis of the functional consequences of mutations in the CF gene.
Human lactoferrin was expressed from a cloned cDNA introduced into mammalian cells in tissue culture. Total RNA was extracted from human bone marrow, and lactoferrin cDNA was synthesized by primer-specific polymerase chain reaction after oligo(dT)-primed first-strand synthesis. The cDNA was sequenced to confirm its identity with previously published human lactoferrin sequences and cloned into the eukaryotic expression vector pNUT. Recombinant vector DNA containing the human lactoferrin sequence was introduced into baby-hamster kidney (BHK) cells in culture, and stable transfectants were produced by dominant marker selection. Human lactoferrin was expressed from the metallothionein promoter of pNUT by Zn2+ induction. The protein was secreted into the tissue-culture medium and was subsequently purified to homogeneity in a single step. Initial characterization suggests that the protein expressed by BHK cells is identical with native human lactoferrin.
BACKGROUND In this multicenter, open‐label, randomized phase 2 trial, the authors evaluated the vascular endothelial growth factor receptor inhibitor axitinib, bevacizumab, or both in combination with chemotherapy as first‐line treatment of metastatic colorectal cancer (mCRC). METHODS Patients with previously untreated mCRC were randomized 1:1:1 to receive continuous axitinib 5 mg twice daily, bevacizumab 5 mg/kg every 2 weeks, or axitinib 5 mg twice daily plus bevacizumab 2 mg/kg every 2 weeks, each in combination with modified 5‐fluorouracil/leucovorin/oxaliplatin (FOLFOX‐6). The primary endpoint was the objective response rate (ORR). RESULTS In all, 126 patients were enrolled from August 2007 to September 2008. The ORR was numerically inferior in the axitinib arm (n = 42) versus the bevacizumab arm (n = 43; 28.6% vs 48.8%; 1‐sided P = .97). Progression‐free survival (PFS) (11.0 months vs 15.9 months; 1‐sided P = .57) and overall survival (OS) (18.1 months vs 21.6 months; 1‐sided P = .69) also were numerically inferior in the axitinib arm. Similarly, efficacy endpoints for the axitinib/bevacizumab arm (n = 41) were numerically inferior (ORR, 39%; PFS, 12.5 months; OS, 19.7 months). The patients who received axitinib had fewer treatment cycles compared with other arms. Common all‐grade adverse events across all 3 treatment arms were fatigue, diarrhea, and nausea (all ≥49%). Hypertension and headache were more frequent in the patients who received axitinib. Patients in the bevacizumab arm had the longest treatment exposures and the highest rates of peripheral neuropathy. CONCLUSIONS Neither the addition of continuous axitinib nor the axitinib/bevacizumab combination to FOLFOX‐6 improved ORR, PFS, or OS compared with bevacizumab as first‐line treatment of mCRC. Cancer 2013;119:2555–2563. © 2013 American Cancer Society.
We complemented the Cl‐ conductance defect in cystic fibrosis lymphocytes by transfection with wild‐type cDNA for the cystic fibrosis transmembrane conductance regulator (CFTR). Stable transfectants were selected and subjected to molecular and functional analyses. We detected expression of endogenous CFTR mRNA in several CF and non‐CF lymphoid cell lines by PCR. Expression from cDNA in the transfectants was demonstrated by amplifying vector‐specific sequences. Both fluorescence and patch‐clamp assays showed that transfectants expressing wild‐type CFTR acquired properties previously associated with Cl‐ conductance (GCl) regulation in non‐CF lymphocytes: (i) GCl was elevated in the G1 phase of the cell cycle, (ii) cells fixed at G1 increase GCl in response to increased cellular cAMP or Ca2+, (iii) agonist‐induced increases in GCl were lost as the cells progressed to the S phase of the cell cycle. The cell cycle and agonist dependent regulation of GCl was not observed in CF lymphocytes transfected with CFTR cDNA containing stop codons in all reading frames at exon 6. Our findings indicate that lymphocytes express functional CFTR since wild‐type CFTR corrects the defects in Cl‐ conductance regulation found in CF lymphocytes. Evaluation of the mechanism of this novel, CFTR‐mediated regulation of GCl during cell cycling should provide further insights into the function of CFTR.
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