Nuclear cathepsin L activity is required for cell cycle progression of colorectal carcinoma cells.
Prominent tasks of cysteine cathepsins involve endo-lysosomal proteolysis and turnover of extracellular matrix constituents or plasma membrane proteins for maintenance of intestinal homeostasis. Here we report on enhanced levels and altered subcellular localization of distinct cysteine cathepsins in adenocarcinoma tissue in comparison to adjacent normal colon. Immunofluorescence and immunoblotting investigations revealed the presence of cathepsin L in the nuclear compartment in addition to its expected endo-lysosomal localization in colorectal carcinoma cells. Cathepsin L was represented as the full-length protein in the nuclei of HCT116 cells from which stefin B, a potent cathepsin L inhibitor, was absent. Fluorescence activated cell sorting analyses with synchronized cell cultures revealed deceleration of cell cycle progression of HCT116 cells upon inhibition of cathepsin L activity, while expression of cathepsin L-enhanced green fluorescent protein chimeras accelerated S-phase entry. We conclude that the activity of cathepsin L is high in the nucleus of colorectal carcinoma cells because of lacking stefin B inhibitory activity. Furthermore, we hypothesize that nuclear cathepsin L accelerates cell cycle progression of HCT116 cells thereby supporting the notion that cysteine cathepsins may play significant roles in carcinogenesis due to deregulated trafficking.
Department of Life Sciences and Chemistry, Jacobs University Bremen, Campus Ring 1, D-28759 Bremen, Germany. Electronic address: triptimani@gmail.com.
Tripti
T
Tamhane
Department of Life Sciences and Chemistry, Jacobs University Bremen, Campus Ring 1, D-28759 Bremen, Germany. Electronic address: illukkum@embl.de.
Rukshala
R
Lllukkumbura
Department of Life Sciences and Chemistry, Jacobs University Bremen, Campus Ring 1, D-28759 Bremen, Germany. Electronic address: shiying.lu@embl.de.
Shiying
S
Lu
Department of Tumor Biology, Institute for Cancer Research, Oslo University Hospital, The Norwegian Radium Hospital, Oslo, Norway. Electronic address: Gunhild.Mari.Malandsmo@rr-research.no.
Gunhild M
GM
Maelandsmo
Department of Life Sciences and Chemistry, Jacobs University Bremen, Campus Ring 1, D-28759 Bremen, Germany; Department of Tumor Biology, Institute for Cancer Research, Oslo University Hospital, The Norwegian Radium Hospital, Oslo, Norway. Electronic address: Mads.Haugland.Haugen@rr-research.no.
Mads H
MH
Haugen
Department of Life Sciences and Chemistry, Jacobs University Bremen, Campus Ring 1, D-28759 Bremen, Germany. Electronic address: k.brix@jacobs-university.de.
Klaudia
K
Brix
D000818:Animals; D018938:Caco-2 Cells; D056668:Cathepsin L / Q000378:metabolism*; D002453:Cell Cycle; D002460:Cell Line; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000201:enzymology*; D015179:Colorectal Neoplasms / Q000201:enzymology* / Q000473:pathology; D011992:Endosomes / Q000201:enzymology*; D004847:Epithelial Cells / Q000201:enzymology; D005455:Fluorescent Antibody Technique; D045325:HCT116 Cells; D006801:Humans; D015151:Immunoblotting; D007422:Intestines / Q000166:cytology / Q000201:enzymology; D008247:Lysosomes / Q000201:enzymology*; D018613:Microscopy, Confocal; D016196:S Phase
D056668:Cathepsin L
Colorectal carcinoma; Trafficking; cysteine cathepsins