Schroy P C, Rustgi A K, Ikonomu E, Liu X P, Polito J, Andry C, O'Keane J C
Department of Medicine, Boston University Medical Center, Massachusetts 02118.
J Cell Physiol. 1994 Oct;161(1):111-23. doi: 10.1002/jcp.1041610114.
The polar-planar compound hexamethylene bisacetamide (HMBA) can inhibit HT29 colon carcinoma cell growth and induce a more benign phenotype, as defined by decreased anchorage-independent clonogenicity, loss of a cell surface malignancy marker, and decreased in vivo tumorigenicity. The principle aim of this study was to determine whether HMBA's effects on HT29 cell growth and biologic behavior correlate with effects on intestinal differentiation. Parallel studies were performed with sodium butyrate (NaBT), a potent inducer of intestinal differentiation. HT29 cell growth, proliferation, and markers of intestinal differentiation were assayed after short- and long-term treatment with HMBA, NaBT, or the combination. Both 5 mM HMBA and 5 mM NaBT were potent inhibitors of monolayer growth; in combination their effects were nearly additive. Inhibition of DNA synthesis was detectable within 6 h of treatment and was preceded by down-regulation of c-myc expression. Soft agar clonogenicity was also decreased by 90%, > 99%, and > 99% by HMBA, NaBT, and the combination, respectively. Despite these parallel effects on growth and in vitro markers of a benign phenotype, effects on intestinal differentiation were discordant. NaBT induced significant increases in membrane-associated alkaline phosphatase activity, cytosolic mucin content, PAS+/diastase-resistant cells, and ultrastructural evidence of intestinal cell differentiation. HMBA not only failed to induce markers of intestinal differentiation, but attenuated NaBT's effects when used in combination. These data suggest that growth and intestinal differentiation may be independently regulated in HT29 cells. They also suggest that expression of intestinal markers of differentiation is not a prerequisite for the acquisition of a more benign phenotype.
极性平面化合物六亚甲基双乙酰胺（HMBA）可抑制HT29结肠癌细胞的生长，并诱导出更良性的表型，其定义为非锚定依赖性克隆形成能力降低、细胞表面恶性标志物丧失以及体内致瘤性降低。本研究的主要目的是确定HMBA对HT29细胞生长和生物学行为的影响是否与对肠道分化的影响相关。同时使用丁酸钠（NaBT）进行平行研究，丁酸钠是一种有效的肠道分化诱导剂。在用HMBA、NaBT或两者组合进行短期和长期处理后，检测HT29细胞的生长、增殖和肠道分化标志物。5 mM HMBA和5 mM NaBT均为单层生长的有效抑制剂；两者联合使用时，其作用几乎是相加的。在处理后6小时内可检测到DNA合成受到抑制，且在此之前c-myc表达下调。HMBA、NaBT及其组合分别使软琼脂克隆形成能力降低90%、>99%和>99%。尽管对生长和良性表型的体外标志物有这些平行影响，但对肠道分化的影响并不一致。NaBT可显著提高膜相关碱性磷酸酶活性、胞质粘蛋白含量、PAS+/抗淀粉酶细胞以及肠道细胞分化的超微结构证据。HMBA不仅未能诱导肠道分化标志物，而且在联合使用时还减弱了NaBT的作用。这些数据表明，HT29细胞中的生长和肠道分化可能受到独立调节。它们还表明，肠道分化标志物的表达不是获得更良性表型的先决条件。
