Prognostic significance of alpha-1-antitrypsin in early stage of colorectal carcinomas

Establishment and characterization of a human lung adenocarcinoma cell line (LC-2/ad) producing alpha 1-antitrypsin in vitro

A new human cell line, LC-2/ad was established from pleural effusion of pulmonary adenocarcinoma of a 51 year old Japanese female. The LC-2/ad cells exhibit an epithelial appearance and a tendency to form small domes as observed with phase-contrast microscopy. The modal chromosome number was 53-56. Plating efficiency and doubling time were 6.8% and 58 h, respectively (32th passage). Immunocytochemically, the cells were strongly positive for CEA and cytokeratins including cytokeratin no. 18 which is present in simple epithelia. Ultrastructurally, the cultured cells were characterized by well-formed junctional complexes and microvilli. Subcutaneous injection of 5 x 10(6) cells into a nude mouse resulted in tumor formation classified histologically as a moderately differentiated adenocarcinoma. This cell line produced at least two functionally active trypsin inhibitors together with several proteinases in vitro. The main inhibitor was purified partially from the serum-free conditioned medium and confirmed immunologically as human alpha 1-antitrypsin (AAT). Immunohistochemically, the xenografted tumor was also positive for AAT. The cell line LC-2/ad is useful for the study of tumor-derived serine proteinase inhibitors, in particular AAT.

Properties of alpha 1-antitrypsin secreted by human adenocarcinoma cell lines

alpha 1-Antitrypsin; (alpha 1-AT) produced by various human carcinoma (non-hepatoma) cell lines were analyzed. Five out of eight cell lines secreted detectable amounts of alpha 1-AT into the conditioned media. All were adenocarcinoma cell lines. The tumor cell-derived alpha 1-ATs had higher molecular weights (MW) than the normal plasma form. Most of this difference was an overall reflection of altered N-glycosylation. As judged by binding of lectins, the glycosylation had shifted towards higher levels of triantennary oligosaccharides and higher levels of fucosylation. The conditioned media also contained lower MW alpha 1-AT species, possibly, proteolytically cleaved forms.

Alpha 1-antitrypsin as a biomarker in azoxymethane induced intestinal tumors in F344 rats

Alpha 1-antitrypsin (alpha 1AT) has been detected in several human tumors and is thought to be a marker of neoplastic change and progression. As the biology of azoxymethane (AOM) induced intestinal tumors in F344 rats has many characteristics of human intestinal tumors, we have investigated alpha 1AT expression in AOM induced rat intestinal tumors. Nine of 12 colonic carcinomas and 6/8 small intestinal carcinomas had alpha 1AT positive tumor cells. Only 1/11 colonic adenomas and 0/3 small intestinal adenomas contained alpha 1AT. Thus alpha 1AT is a marker of malignancy in this model. Inhibition of carcinogenesis by piroxicam and difluoromethyl ornithine inhibited alpha 1AT expression.

Proteinases and proteinase inhibitors as modulators of animal cell growth

1. Three distinct lines of evidence indicate that proteinases are involved in the growth of cultured animal cells. 2. Endogenous growth-related proteinases have been identified, and exogenous proteinases can also stimulate cell proliferation, probably by different mechanisms. In some cases, higher concentrations of proteinases are cytotoxic. 3. Proteinase inhibitors, not surprisingly, inhibit cell growth, but can also be mitogenic at sub-inhibitory concentrations. 4. There must, therefore, be at least three major cellular processes in which proteinases or proteinase inhibitors can operate to exert a direct effect on cell proliferation. 5. Details of one action of an exogenous proteinase, typified by thrombin and the thrombin receptor, are becoming clear at the molecular level, but thrombin probably activates at least two intracellular signalling systems, as well as acting as a growth inhibitor in some situations. 6. Much remains to be investigated in other examples.

An evaluation of the prognostic significance of alpha-1-antitrypsin expression in adenocarcinomas of the lung: an immunohistochemical analysis

Expression of alpha-1-antitrypsin (AAT) in tumour cells of 102 surgically resected lung adenocarcinomas was examined by immunohistochemical method using anti-AAT antiserum. While only 13 cases (13%) were negative for AAT expression, 89 cases (87%) contained AAT at varying degrees. The degree of AAT-positive tumour cells was significantly higher in advanced cases than in early cases. Clinical follow-up study of the patients, particularly in stage I, showed that strongly AAT-positive cases have poor prognosis than weak-to-moderately AAT-positive or AAT-negative cases. Thus, AAT expression status in tumour cells of lung adenocarcinoma may be a biological marker of prognostic significance in regard to tumour growth.

Establishment of a new human cancer cell line secreting protease nexin-II/amyloid beta protein precursor derived from squamous-cell carcinoma of lung

A new cell line (LC-1/sq) of human lung squamous-cell carcinoma was established from a surgically resected specimen of primary lung cancer. Upon continuous propagation in serum-free culture medium, it secreted trypsin inhibitors into the conditioned medium. The major fraction of the trypsin inhibitor (T1-1) was purified to apparent homogeneity by anion-exchange and gel-filtration high-performance liquid chromatography (HPLC) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) followed by transblotting to Immobilon. T1-1 effectively inhibited trypsin. Chymotrypsin, plasmin and kallikrein were inhibited to a lesser extent, but urokinase-type plasminogen activator, elastase, thrombin and papain were not inhibited. The activity of T1-1 was acid-stable and heat-resistant, and its molecular weight was 115 kDa by SDS-PAGE. It exhibited single NH2-terminal sequence, and its first 20 NH2-terminal amino-acid residues were identical with those of protease nexin-II (PN-II)/amyloid beta-protein precursor (APP). These characteristics of T1-1 suggest that the major trypsin inhibitor secreted by LC-1/sq is indistinguishable from PN-II/APP. LC-1/sq is the first lung squamous carcinoma cell line that secretes functionally active trypsin inhibitor, PN-II/APP, in vitro and is useful for studying its biological significance in malignant tumor.

Expression of pancreatic secretory trypsin inhibitor (PSTI) in colorectal cancer

We examined the expression of pancreatic secretory trypsin inhibitor (PSTI) in colorectal cancer by immunohistochemical staining using an anti-PSTI antiserum, an in situ hybridisation technique utilising sulphonated PSTI cDNA probe, and a Northern blot hybridisation method, using a 32P-labelled PSTI cDNA probe. Immunohistochemically, PSTI was detected in 80 of 95 (84%) colorectal cancer cases. Analyses with in situ hybridisation as well as Northern blot hybridisation demonstrated PSTI mRNAs in immunohistochemically positive cases, showing PSTI could be produced in colorectal cancerous cells. Histologically well or moderately differentiated adenocarcinoma showed higher incidence of PSTI immunoreactivity than the other types. Furthermore, the intensity of the immunohistochemical staining for PSTI increased the more cases advanced, particularly in regard to depth of invasion and tumour size. Thus, PSTI expression is widespread in colorectal cancer, and occurs more commonly in advanced cases. Considering the suggestion that PSTI is a growth-stimulating factor as an well as inhibitor to proteolytic proteinase, the present findings may indicate that PSTI expressed in colorectal cancerous cells may play a role possibly closely associated with tumour development.