Hollow spheroids beyond the invasive front and malignant potential of colorectal cancer.

Abstract

418 Background: Hollow spheroid (HS) is a morophogenesis after budding at invasion front of colorectal cancer (CRC) tissue. HS formation of CRC cells has been shown to be induced by Carcinoembryonic Antigen-related Cell Adhesion Molecule 1 (CEACAM1) long cytoplasmic isoform dominance condition in three-dimensional (3D) in vitro culture. The aim of the current study is to address the existence and the clinical implication of HS in colorectal cancer. Methods: Immunohistochemical analyses were conducted with CEACAM1, CEACAM1-L, to address the existence of CEACAM1 expressing HS beyond the invasion front of CRC. The risk factors for metastases and survival were calculated using univariate and multivariate analyses on clinical samples from 164 patients with CRC. To investigate the role of HS for chemoresistance to 5-fluorouracil (5-FU), the risk factors for recurrence after adjuvant chemotherapy were calculated using univariate and multivariate analyses on clinical samples from 82 patients with Stage III CRC. Results: Immunohistochemical analyses showed that CEACAM1 expressing HS existed at the invasion front of colorectal cancer tissues. A multivariate analysis showed that the HS is an independent risk factor for lymph node metastasis (p = 0.004) and distant metastasis (p = 0.002). HS was also identified to be an independent prognostic factor by a Cox proportional hazards model (p = 0.020). The Kaplan-Meier evaluation for the overall survival analysis showed that HS was significantly associated with a shorter survival (p < 0.0001). Moreover, a multivariate analysis for recurrence after adjuvant chemotherapy showed that the HS is an independent risk factor (p = 0.0079). These results suggested that HS indicates malignant and chemoresistant phenotype. Conclusions: HS was significantly correlated with CRC metastasis, poor survival and chemoresistance to 5-FU. HS beyond the invasion front of CRC can be useful for diagnosis of malignant potential, and may be novel therapeutic target.