Due to low α-amylase sensitivity, stress influences might cause a less regulated cell proliferation in F344 breast tissue. In contrast to this, mammary Lewis cell proliferation was well regulated showing rather soon signs of senescence. These considerations are supported by the observation that

F344 cells attached easier and grew faster than Lewis cells (Figure 1a & b). α-Amylase was detected in both, F344 and Lewis CH5424802 concentration primary mammary epithelial cells (Figure 1c & d) without obvious differences. Moreover, we recently determined amylase enzyme activity in the mammary gland tissue of F344 and Lewis rats and observed no differences in activity between both rat strains (unpublished data). These findings indicate that other factors than α-amylase protein expression and activity must underlie the observed differences. Thus, the α-amylase efficacy on its targets is probably altered in F344 cells participating in less BIRB 796 in vivo regulation of cellular proliferation. However, the enzymatic preparation of mammary gland tissue

might alter cell surface and therefore influence adhesion properties in vitro. Microenvironmental influences in the breast tissue, which strongly affect cellular behavior [46–48] and which are absent or at least altered in our primary cultures in vitro, should also be considered. Currently, the possible mechanisms underlying antiproliferative effects of α-amylase remain unclear. However, some sources in literature can be found that allow considerations about a possible mechanism and probable α-amylase targets. α-Amylase might act on molecules, which mediate cell adhesion,

and stimulate detachment and death of cells called anoikis, a type of apoptosis Ureohydrolase [49, 50]. In our experiments, the proportion of dead cells reflects the sensitivity to trypsin used for cell detachment prior to counting. If α-amylase induces anoikis by action on cellular adhesion, a more pronounced trypsin effect would have been expected that is negatively correlated with number of cells. This was not the case in either, F344 and Lewis cells. Furthermore, α-amylase could probably stimulate cellular differentiation or senescence. Investigations of cell senescence by SA-β-gal assay presented here did not show a strong impact of α-amylase on senescence, particularly not in combination with the effect on cell growth. α-Amylase also exerts antibacterial effects, which are either drawn back to an inhibition of bacteria growth by diminishing nutrients [10] or to a direct interaction with α-amylase [11]. Regarding cell culture, known α-amylase-substrates, like starch, are usually not present in cell culture media, but an α-amylase effect by metabolism of nutrients cannot be completely excluded.