Increasing evidence supports the involvement of cholinesterases in tumorigenesis. Several tumour cells show ChE activity, while the acetyl- (AChE) and butyrylcholinesterase (BuChE) genes are amplified in leukemias, ovarian carcinoma and other cancers. ChE activity was measured in 31 samples of tumoral breast (TB) and 20 of normal breast (NB). Despite the wide variations observed, BuChE predominated over AChE both in TB and NB. The mean AChE activity in NB was 1.61 nmol of the substrate hydrolysed per minute and per miligram protein (mU/mg), which rose to 3.09 mU/mg in TB (p = 0.041). The BuChE activity dropped from 5.24 mU/mg in NB to 3.39 mU/mg in TB (p = 0.002). Glycolipid-linked AChE dimers and monomers and hydrophilic BuChE tetramers and monomers were identified in NB and TB, and their proportions were unmodified by the neoplasia. The amount of AChE forms reacting with wheat germ agglutinin (WGA) decreased in TB while that of BuChE species was unaffected, demonstrating that the glycosylation of AChE was altered in TB. The binding of AChE and BuChE with antibodies was unaffected by the neoplasia. The difference in lectin reactivity between erythrocyte and breast AChE, the lack of AChE in blood plasma, and the finding of monomeric BuChE in breast but not in plasma suggest that breast epithelial cells produce AChE for membrane attachment and hydrophilic BuChE for secretion. Several reasons are provided to explain the altered expression of ChEs in breast cancer.

Because of the probable involvement of cholinesterases (ChEs) in tumorigenesis, this research was addressed to ascertaining whether breast cancer metastasis alters the content of acetylcholinesterase (AChE) and/or butyrylcholinesterase (BuChE) in axillary lymph nodes (LN). ChE activity was assayed in nine normal (NLN) and seven metastasis-bearing nodes (MLN) from women. AChE and BuChE forms were characterised by sedimentation analyses, hydrophobic chromatography and western blotting. The origin of ChEs in LN was studied by lectin interaction. AChE activity dropped from 21.6 mU/mg (nmol of the substrate hydrolysed per minute and per milligram protein) in NLN to 3.8 mU/mg in MLN (p < 0.001), while BuChE activity (3.6 mU/mg) was little affected. NLN contained globular amphiphilic AChE dimers (G2A, 35%), monomers (G1A, 30%), hydrophilic tetramers (G4H, 8%), and asymmetric species (A4, 23%, and A8, 4%); MLN displayed only G2A (65%) and G1A (35%) AChE forms. NLN and MLN contained G4H (79%), G4A (7%), and G1H (14%) BuChE components. Neither the binding of ChE forms with lectins and antibodies nor the subunit size were altered by metastasis. The higher level of AChE in NLN than in brain and the specific pattern of AChE forms in NLN support its role in immunity. The different profile of AChE forms in NLN and MLN may be useful for diagnosis.

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Hypothesis: There are differences between readings of peripheral blood oxygen saturation when the effect on saturation values of methylene blue is compared with that of isosulfan blue when used in sentinel lymph node biopsy in patients with breast cancer.

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