title: CD74 interferes with the expression of fas receptor on the surface of lymphoma cells.
abstract: BACKGROUND
  Resistance to Fas-mediated apoptosis limits the efficacy of currently available chemotherapy regimens. We identified CD74, which is known to be overexpressed in hematological malignancies, as one of the factors interfering with Fas-mediated apoptosis.
  
  
  METHODS
  CD74 expression was suppressed in human B-lymphoma cell lines, BJAB and Raji, by either transduction with lentivirus particles or transfection with episomal vector, both encoding CD74-specific shRNAs or non-target shRNA. Effect of CD74 expression on Fas signaling was evaluated by comparing survival of mice hydrodynamically transfected with vector encoding full-length CD74 or empty vector. Sensitivity of cells with suppressed CD74 expression to FasL, edelfosine, doxorubicin, and a humanized CD74-specific antibody, milatuzumab, was evaluated by flow cytometry and compared to control cells. Fas signaling in response to FasL stimulation and the expression of Fas signaling components were evaluated by Western blot. Surface expression of Fas was detected by flow cytometry.
  
  
  RESULTS
  We determined that cells with suppressed CD74 are more sensitive to FasL-induced apoptosis and Fas signaling-dependent chemotherapies, edelfosine and doxorubicin, than control CD74-expressing cells. On the other hand, expression of full-length CD74 in livers protected the mice from a lethal challenge with agonistic anti-Fas antibody Jo2. A detailed analysis of Fas signaling in cells lacking CD74 and control cells revealed increased cleavage/activation of pro-caspase-8 and corresponding enhancement of caspase-3 activation in the absence of CD74, suggesting that CD74 affects the immediate early steps in Fas signaling at the plasma membrane. Cells with suppressed CD74 expression showed increased staining of Fas receptor on their surface. Pre-treatment with milatuzumab sensitized BJAB cells to Fas-mediated apoptosis.
  
  
  CONCLUSIONS
  We anticipate that specific targeting of the CD74 on the cell surface will sensitize CD74-expressing cancer cells to Fas-mediated apoptosis, and thus will increase effectiveness of chemotherapy regimens for hematological malignancies.
authors.affiliation: Department of Lymphoma and Myeloma, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX, 77030, USA. zberkova@mdanderson.org.
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Berkova
authors.affiliation: Department of Lymphoma and Myeloma, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX, 77030, USA. shu_wang@mdanderson.org.
authors.forename: Shu
authors.initials: S
authors.lastname: Wang
authors.affiliation: Department of Lymphoma and Myeloma, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX, 77030, USA. xao@mdanderson.org.
authors.forename: Xue
authors.initials: X
authors.lastname: Ao
authors.affiliation: Department of Lymphoma and Myeloma, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX, 77030, USA. Jillian.Wise@rr-research.no.
authors.forename: Jillian F
authors.initials: JF
authors.lastname: Wise
authors.affiliation: Department of Lymphoma and Myeloma, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX, 77030, USA. fkbraun@mdanderson.org.
authors.forename: Frank K
authors.initials: FK
authors.lastname: Braun
authors.affiliation: Department of Lymphoma and Myeloma, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX, 77030, USA. ahrezaeian@mdanderson.org.
authors.forename: Abdol H
authors.initials: AH
authors.lastname: Rezaeian
authors.affiliation: Department of Lymphoma and Myeloma, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX, 77030, USA. lsehgal@mdanderson.org.
authors.forename: Lalit
authors.initials: L
authors.lastname: Sehgal
authors.affiliation: Immunomedics, Inc., Morris Plains, NJ, 07950, USA. dmg@Immunomedics.com.|Center for Molecular Medicine and Immunology, Garden State Cancer Center, Morris Plains, NJ, 07950, USA. dmg@Immunomedics.com.
authors.forename: David M
authors.initials: DM
authors.lastname: Goldenberg
authors.affiliation: Department of Lymphoma and Myeloma, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX, 77030, USA. fsamaniego@mdanderson.org.
authors.forename: Felipe
authors.initials: F
authors.lastname: Samaniego
mesh_terms: D000818:Animals; D061067:Antibodies, Monoclonal, Humanized / Q000494:pharmacology; D000944:Antigens, Differentiation, B-Lymphocyte / Q000235:genetics / Q000378:metabolism*; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000494:pharmacology; D053222:Fas Ligand Protein / Q000494:pharmacology; D000949:Histocompatibility Antigens Class II / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D019169:Jurkat Cells; D008099:Liver / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D016393:Lymphoma, B-Cell / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D008810:Mice, Inbred C57BL; D010742:Phospholipid Ethers / Q000494:pharmacology; D034622:RNA Interference; D015398:Signal Transduction; D014162:Transfection; D019014:fas Receptor / Q000378:metabolism*
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D000944:Antigens, Differentiation, B-Lymphocyte; D000970:Antineoplastic Agents; C491901:FAS protein, human; D053222:Fas Ligand Protein; D000949:Histocompatibility Antigens Class II; D010742:Phospholipid Ethers; D019014:fas Receptor; C045084:invariant chain; C026659:edelfosine; C540932:milatuzumab; D004317:Doxorubicin