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Proliferation, Invasion and p16 Localisation in Malignancies

Author:
  • Kristina Nilsson
Publishing year: 2006
Language: English
Pages: 107
Publication/Series: Lund University, Faculty of Medicine Doctoral Dissertation Series
Document type: Dissertation
Publisher: Department of Laboratory Medicine, Lund University

Summary

Popular Abstract in Swedish

Okontrollerad proliferation och invasion är två viktiga egenskaper i tumörutveckling och tumörprogression. Tidigare studier har visat att invaderande tumörceller i kolorektalcancer har låg proliferation parallellt med en uppreglering av tumörsuppressorn p16. Vi undersökte p16-uttrycket och proliferation i basalcellscancer och skivepitelcancer i huden, tumörer som är lokalt infiltrativa och aggressiva. p16 var uppreglerat i invasiva celler jämfört med celler i centrala delar i båda tumörerna, och i basalcellscancer fann vi en minskad proliferation i celler med högt p16-uttryck. I skivepitelcancer var Rb-vägen inte funktionell, troligtvis genom inaktivering av Rb, eller genom en de-lokalisering av p16 till cytoplasman, varpå p16 inte kunde inhibera proliferation i de infiltrerande cellerna. Till skillnad mot i de maligna hudtumörerna uttrycktes p16 centralt i tumöröarna i cylindrom, och i denna benigna långsamtväxande hudtumör tycktes p16 viktig för att inhibera proliferationen. Vidare visade vi, genom subcellulär fraktionering, att p16 uttrycktes i både kärnan och cytoplasman i vissa tumörcellinjer, och att proteinet kunde binda till cdk4/6 på båda ställena, även om det inte kan inhibera proliferationen. När vi undersökte post-translationella modifieringar av p16 fann vi minst två former av p16 i tumörcellinjer och i hudtumörer. Vi undersökte vidare förhållandet mellan tumörcellsproliferation och migration i en bröstcancercellinje och fann att vilande celler var mer migratoriska än aktivt delande celler. Detta verifierades dessutom i primära brösttumörer där vi fann ett inverst förhållande mellan proliferation och infiltrativt växtsätt. Dock kunde de aktivt delande cellerna bli mer migratoriska vid exponering för ett makrofagliknande stimulus. Sammanfattningsvis tycks proliferation och invasion/migration inte ske samtidigt i vissa tumörceller. I andra tumörer, möjligtvis med större fel i cellcykelregulatoriska vägar, kan cellerna däremot proliferera och migrera samtidigt.
Uncontrolled proliferation and invasion are two characteristics in tumour development and progression. Previous studies have shown that invading tumour cells in colorectal cancer have low proliferation in parallel to upregulation of the tumour suppressor p16. We set out to detail the p16 expression and proliferation in basal cell carcinoma and squamous cell carcinoma of the skin, tumours that are locally infiltrative and aggressive. p16 was upregulated at the invasive margin compared to central parts in both tumours, and in basal cell carcinoma there was also a decreased proliferation in infiltrating p16 high tumour cells. In squamous cell carcinoma the Rb-pathway was non-functional, probably due to inactivation of Rb or a de-localisation of p16 to the cytoplasm, and p16 could consequently not inhibit proliferation in infiltrating cells. In contrast to the malignant skin tumours, p16 was commonly expressed in central parts of the tumour islands in cylindroma, and in this benign slow growing tumour p16 seemed important in restraining the proliferative activity of the tumour cells. Further, by subcellular fractionation we confirmed that p16 was expressed in both the nucleus and in the cytoplasm in tumour cell lines, and the protein could bind to cdk4/6 in both subcellular compartments, even if it seemed incapable of inhibiting proliferation. Investigating post-translational modifications of p16 revealed at least two forms of p16 in cell lines, as well as in skin tumours. We further investigated the relation between tumour cell proliferation and migration in a breast cancer cell line and observed that resting cells were more migratory than actively cycling cells. This was also confirmed in a cohort of primary breast tumours, where proliferation and infiltrative growth pattern were inversely correlated. However, the actively cycling breast tumour cells could be rendered more migratory upon exposure to macrophage like stimuli. Thus, in some tumour cells, proliferation and invasion/migration seem to be contrasting events. However, in other tumours, potentially with more severe aberrations in cell cycle regulatory pathways, the cells can proliferate and migrate concurrently.

Disputation

2006-11-24
09:00
Main lecture hall, Pathology building entrance 78, Malmö University Hospital, Malmö
  • Pierre Åman (Professor)

Keywords

  • Cancer and Oncology
  • Cell and Molecular Biology
  • onkologi
  • Cytologi
  • cancerology
  • Cytology
  • oncology
  • skin tumours
  • invasion
  • p16
  • cancer
  • patologisk anatomi
  • Patologi (allmän)
  • pathological anatomy
  • proliferation
  • General pathology

Other

Published
  • Pathology, Malmö
  • Göran Landberg
  • ISSN: 1652-8220
  • ISBN: 91-85559-51-2