Date of Award

1993

Degree Type

Thesis

Degree Name

M.Sc.

Department

Biological Sciences

First Advisor

Dufresne, M. J.

Keywords

Biology, Cell.

Rights

CC BY-NC-ND 4.0

Abstract

The expression of the lysosomal cysteine proteases, cathepsins B, H, and L, and cysteine protease inhibitors in intracellular (cells) and extracellular (media) fractions prepared from the MCF-7 human breast cancer cell line, its adriamycin resistant variant, MCF-7/Adr$\sp{\rm R}$, and their somatic cell hybrid, M:A, was examined using synthetic substrates. Although these three cell populations had similar growth parameters, MCF-7/Adr$\sp{\rm R}$ demonstrated statistically significant 10-25 fold and 10-15 fold higher levels of intracellular cathepsins B and L activities respectively, than those found in the MCF-7 parent, or the M:A hybrid. Moreover, the increased levels of cathepsins B and L observed in MCF-7/Adr$\sp{\rm R}$ were not observed in either gpt or ras/gpt transfected MCF-7 cells. Cathepsin H activities were similar in all MCF-7 populations examined. The pattern of expression of acid/pepsin activatable cathepsin B in extracellular fractions of MCF-7, MCF-7/Adr$\sp{\rm R}$, and M:A was similar to that observed in intracellular fractions. Analysis of free and total cysteine protease inhibitor levels in MCF-7 and MCF-7/Adr$\sp{\rm R}$ cells using FPLC suggested MCF-7 cells possessed almost twice the total inhibitor level of MCF-7/Adr$\sp{\rm R}$, but retained better than half of this activity in a protease bound (ie., inactive) form. These results support the conclusion that alterations in the levels of total cysteine protease inhibitors, may contribute to increased levels of cathepsin B and L activity in MCF-7/Adr$\sp{\rm R}$ cells.Dept. of Biological Sciences. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1993 .S372. Source: Masters Abstracts International, Volume: 32-06, page: 1582. Adviser: Michael Dufresne. Thesis (M.Sc.)--University of Windsor (Canada), 1993.

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