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Reactive center loop moiety is essential for the maspin activity on cellular invasion and ubiquitin-proteasome level

Chakkrit Khanaree1, Kongthawat Chairatvit, Sittiruk Roytrakul

  • 1Department of Biochemistry, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.

Oncology Research
|August 9, 2013
PubMed

Insights

Maspin, a tumor suppressor protein, inhibits cancer metastasis by enhancing cell adhesion. Its tumor-suppressive function is located in the reactive center loop (RCL) domain, impacting cell migration and invasion.

Area of Science:

  • Oncology
  • Molecular Biology
  • Biochemistry

Background:

  • Maspin (SERPINB5) is a tumor suppressor inhibiting cancer cell migration, invasion, and metastasis.
  • Maspin's tumor-suppressive effects are linked to enhanced cell adhesion to the extracellular matrix.
  • The precise molecular mechanism of maspin remains unclear, but its reactive center loop (RCL) is hypothesized to be the functional domain.

Purpose of the Study:

  • To elucidate the role of the maspin reactive center loop (RCL) in regulating cancer cell adhesion, migration, and invasion.
  • To investigate the impact of maspin RCL mutations on the invasive properties of human breast carcinoma cells.
  • To analyze proteomic and ubiquitin-proteasome pathway alterations associated with maspin RCL activity.

Main Methods:

  • Transfection of MDA-MB-231 breast carcinoma cells with wild-type maspin, ovalbumin, and maspin/ovalbumin RCL chimeric mutants (MOM and OMO).
  • Assessment of cell adhesion to fibronectin and in vitro migration and invasion through Matrigel.
  • Proteomics analysis to identify changes in protein expression, focusing on metastasis-associated proteins and the ubiquitin-proteasome pathway.
  • Measurement of ubiquitin and ubiquitinated conjugates levels and 20S proteasome chymotrypsin-like activity.

Main Results:

  • Maspin and the OMO chimera significantly increased cell adhesion to fibronectin and reduced migration and invasion compared to controls.
  • Proteomic analysis revealed decreased levels of metastasis-promoting proteins and ubiquitin-proteasome pathway components in maspin/OMO-transfected cells.
  • Maspin and OMO expression led to increased ubiquitin and ubiquitinated conjugates, alongside reduced 20S proteasome chymotrypsin-like activity.
  • The MOM chimera, lacking the maspin RCL, did not exhibit these suppressive effects.

Conclusions:

  • The reactive center loop (RCL) domain of maspin is essential for its tumor-suppressive properties.
  • Maspin's RCL inhibits cancer cell metastasis by modulating cell adhesion and the ubiquitin-proteasome pathway.
  • Targeting the maspin RCL may offer a therapeutic strategy for inhibiting cancer progression and metastasis.

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