Purification of Gastric Mucosal Growth Factor

急性胃粘膜损伤（AGML）患者血浆提取物和盐酸乙醇诱发的AGML大鼠血浆提取物对人胃癌细胞株KATO Ⅲ和培养的豚鼠胃粘膜细胞均有促生长作用。通过羟基磷灰石凝胶层析、葡聚糖凝胶层析和生物凝胶层析对促生长活性物质进行了纯化，得到了两种不同促生长活性物质的纯化产物。最小的一个（m）W. 6，000）通过特异性放射免疫测定发现是TFG-alhpa。最大的一个（m）W. 80，000）进一步用HPLC和SDS-PAGE纯化，然后应用肽序列分析仪测定，表明这种活性[胃粘液生长因子（GM-GF）]具有部分氨基酸序列Phe-Leu-Pro-Glu-Arg-Tyr。前列腺素E_2（PGE_2）和降钙素。三种药物均能促进豚鼠胃粘膜细胞的生长，其作用大小顺序为GM-GF> TGF-α =胃泌素>PGE_2>降钙素。相比之下，仅GM-GF、TGF-α和胃泌素对人胃癌细胞系KATO III的生长有刺激作用，其作用强度顺序为TGF-α =胃泌素>GM-GF，而PGE_2和降钙素均具有抑制作用。另一方面，PGE_2和降钙素不仅能促进胃粘膜细胞而且能促进KATO Ⅲ细胞环腺苷酸的生成，而胃泌素则能促进肌醇磷脂的更新，从而使两种细胞的[Ca^++]i升高。相反，GM-GF增强酪氨酸磷酸化，同时在正常粘膜细胞和癌细胞中[Ca ++]i增加，尽管像肝细胞生长因子一样，GM-GF似乎对正常上皮细胞比对癌细胞更有效。

Plasma extracts not only from patients with acute gastric mucosal lesion (AGML) but also from rats with AGML induced by HC1-ethanol administration were found to possess growth promoting effects on human gastric carcinoma cell line KATO III as well as on cultured mucosal cells from guinea pig stomach. The growth promoting activities were sequentially purified by hydroxy-apatite gel-chromatography, Sephadex gel chromatography, and Bio-gel chromatography, which resulted in purification of the two distinct growth promoting activities. The smaller one (m. w. 6, 000) was found to be TFG-alhpa by specific radioimmunoassay. The larger one (m. w. 80, 000) was further purified with HPLC and SDS-PAGE followed by application to Peptide sequencer, and it was shown that this activity[Gastric Mucosal Growth Factor (GM-GF) ] has partial amino acid sequence of Phe-Leu-Pro-Glu-Arg-Tyr.The effects of the purified GM-GF on the growth of not only normal gastric mucosa but also gastric cancer cells were compared with those of gastrin, TGF-alpha, prostaglandin E_2 (PGE_2) and calcitonin. All of these agents enhance the growth of mucosal cells from guinea pig stomach with the potency order of GM-GF>TGF-alpha = gastrin>PGE_2>calcitonin. In contrast, the growth of human gastric carcinoma cell line KATO III were stimulated by only GM-GF, TGF-alpha and gastrin with the potency order of TGF-alpha = gastrin>GM-GF, whereas both PGE_2 and calcitonin had inhibitory effects. On the other hand, both PGE_2 and calcitonin enhance cyclic AMP generation in not only gastric mucosal cells but also KATO III cells, while gastrin enhances inositolphospholipid turnover with resulting elevation of[Ca^<++>]i in both cells. In contrast, GM-GF enhances tyrosine phosphorylation with concomitant increase of [Ca^<++>]i in both normal mucosal cells and cancer cells, although like hepatocyte growth factor, GM-GF appears to be more effective on normal epithelial cells than on cancer cells.