* Surfactant protein D suppresses lung cancer progression by downregulation of epidermal growth factor signaling.
- Surfactant protein D (SP-D) is a member of the collectin family that has an important role in maintaining pulmonary homeostasis. In this study, we demonstrated that SP-D inhibited the proliferation, migration and invasion of A549 human lung adenocarcinoma cells. We found that SP-D suppressed epidermal growth factor (EGF) signaling in A549 cells, H441 human lung adenocarcinoma cells and human EGF receptor (EGFR) stable expression CHO-K1 cells. A binding study using (125)I-EGF demonstrated that SP-D downregulated the binding of EGF to EGFR. A ligand blot indicated that SP-D bound to EGFR, and a lectin blot suggested that EGFR in A549 cells had both high-mannose type and complex type N-glycans. We purified the recombinant extracellular domain of EGFR (soluble EGFR=soluble EGFR (sEGFR)), and demonstrated that SP-D directly bound to sEGFR in a Ca(2+)-dependent manner. The binding of SP-D to sEGFR was suppressed by EDTA, mannose or N-glycopeptidase F treatment. Mass spectrometric analysis indicated that N-glycans in domain III of EGFR were of a high-mannose type. These data suggest that SP-D reduces EGF binding to EGFR through the interaction between the carbohydrate recognition domain of SP-D and N-glycans of EGFR, and downregulates EGF signaling. Our finding suggests the novel type of regulation system of EGF signaling involving lectin-to-carbohydrate interaction and downregulation of ligand binding.
Overview of verb demonstrate
The verb demonstrate has 4 senses (first 4 from tagged texts)
1. (24) show, demo, exhibit, present, demonstrate -- (give an exhibition of to an interested
audience; "She shows her dogs frequently"; "We will demo the new software in Washington")
2. (22) prove, demonstrate, establish, show, shew -- (establish the validity of something, as by an
example, explanation or experiment; "The experiment demonstrated the instability of the compound";
"The mathematician showed the validity of the conjecture")
3. (2) attest, certify, manifest, demonstrate, evidence -- (provide evidence for; stand as proof of;
show by one's behavior, attitude, or external attributes; "His high fever attested to his illness";
"The buildings in Rome manifest a high level of architectural sophistication"; "This decision
demonstrates his sense of fairness")
4. (1) demonstrate, march -- (march in protest; take part in a demonstration; "Thousands
demonstrated against globalization during the meeting of the most powerful economic nations in
Seattle")
Overview of adj demonstrated
The adj demonstrated has 1 sense (first 1 from tagged texts)
1. (1) demonstrated -- (having been demonstrated or verified beyond doubt)
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