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Expression of RCAS1 and its function in human squamous cell carcinoma of the oral cavity

Masakatsu Fukuda1, Akio Tanaka, Aya Hamao

  • 1Second Department of Oral and Maxillofacial Surgery, Meikai University School of Dentistry, Sakado, Saitama 350-0283, Japan. fukudam@dent.meikai.ac.jp

Oncology Reports
|July 16, 2004
PubMed

Insights

Receptor-binding cancer antigen expressed on SiSo cells (RCAS1) is found in most oral cancers. RCAS1 expression correlates with tumor progression and may help oral tumors evade immune detection.

Area of Science:

  • Oncology
  • Immunology
  • Molecular Biology

Background:

  • Receptor-binding cancer antigen expressed on SiSo cells (RCAS1) is a tumor antigen implicated in immune evasion.
  • Its role in oral squamous cell carcinomas (HOSCCs) and its mechanism of immune escape require further investigation.

Purpose of the Study:

  • To determine RCAS1 expression in HOSCCs and HOSCC cell lines.
  • To investigate if RCAS1 induces apoptosis in receptor-positive cells, including peripheral blood lymphocytes (PBLs).
  • To explore the association between RCAS1 expression and oral cancer progression.

Main Methods:

  • Detection of RCAS1 transcripts and proteins in HOSCC cell lines (HSC-2, -3, -4, Ca9-22, KB).
  • Immunohistochemical analysis of RCAS1 in 40 HOSCC tissue samples.
  • Confocal laser microscopy, DNA fragmentation assays, and Western dot blotting to assess apoptosis induction and soluble RCAS1 secretion.
  • TUNEL assay to detect apoptotic tumor-infiltrating lymphocytes (TILs).

Main Results:

  • RCAS1 transcripts and proteins were detected in all five HOSCC cell lines studied.
  • RCAS1 was expressed in 80% of HOSCC cases, with expression levels increasing with advanced tumor stage (pTNM).
  • IL-2-stimulated PBLs underwent apoptosis when co-cultured with RCAS1-expressing KB cells, and soluble RCAS1 was detected in culture supernatants.
  • Apoptotic TILs were observed near RCAS1-positive tumor cells in HOSCC tissues.

Conclusions:

  • RCAS1 is frequently expressed in HOSCCs and its expression is associated with tumor progression.
  • RCAS1-expressing tumor cells can induce apoptosis in lymphocytes, suggesting a mechanism for immune escape in oral cancer.
  • RCAS1 represents a potential therapeutic target for overcoming immune evasion in oral tumors.

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