Resistance to 5-fluorouracil (5‑FU), a key drug in the treatment of colorectal cancer, is one of the major reasons for poor patient prognosis during cancer treatment. Annexin A1 (ANXA1) is a calcium‑dependent phospholipid‑linked protein that is associated with drug resistance, anti‑inflammatory effects, regulation of cellular differentiation, proliferation and apoptosis. Although there have been several studies investigating ANXA1 expression in drug resistant cells, the role of ANXA1 is yet to be fully understood. We therefore, in this study, generated SW480 cells resistant to 5‑FU (SW480/5‑FU) to evaluate ANXA1 expression. When compared to the control cells, ANXA1 expression was significantly induced in the SW480/5‑FU cells. We then revealed the role of ANXA1 expression in 5‑FU resistance by using overexpression and knockdown methods in colon cancer cells. Overexpression of ANXA1 induced a significant increase of cell viability to 5‑FU, whereas ANXA1 knockdown induced a significant decrease of cell viability to 5‑FU. Further experiments revealed that ANXA1 expression was induced by hypoxia in colon cancer cells. These results suggest that ANXA1 expression may play a critical role in 5‑FU resistance and may be induced by hypoxia during cancer progression. Our results provide a possible strategy to overcome 5‑FU resistance by modulating ANXA1 expression.

Abstract. Annexin A1 (ANXA1) is a calcium-dependent phospholipid-linked protein, involved in anti-inflammatory effects, regulation of cellular differentiation, proliferation and apoptosis. While many studies have investigated the ANXA1 expression in various tumor types, the role of ANXA1 is not fully understood. Therefore, in the present study, we evaluated the ANXA1 expression in 211 breast cancer patients and compared the levels with clinicopathological factors. ANXA1 was positively expressed in 31 (14.7%) of the 211 cases in our cohort, and these positive cases were associated with triple-negative breast cancer (TNBC) (P=0.007) and venous invasion (P=0.028). The in vitro cell experiment found that the MDA-MB-231 cell line, which is a TNBC cell line, highly expressed ANXA1. Using this cell line, the functional role of ANXA1 in breast cancer was revealed and the knockdown of ANXA1 by specific siRNA demonstrated a significant reduction in cellular invasion. Further experiments indicated that ANXA1 was induced by hypoxia with hypoxia-inducible factor-1α induction. These results suggested that ANXA1, which enhanced breast cancer invasion and metastasis under hypoxia, were significantly associated with the worst patient outcome. This is particularly noted in TNBC, the group of breast cancer with the worst outcome for which new therapeutic implications are required. IntroductionBreast cancer is a leading cause of cancer related mortality among females worldwide and its incidence and mortality rate have been increasing throughout the recent years (1). The treatment of breast cancer has progressed over the past three decades with the development of the combination of chemotherapy, endocrine therapies and human epidermal growth factor receptor 2 (HER2)-targeted therapies (2-5). However, triple-negative breast cancer (TNBC), which is defined by the lack of the estrogen receptor (ER), the progesterone receptor (PgR) and HER2 expression, has not fully benefited from such advances in treatment. Therefore, patients with TNBCs are currently categorized as a sub group with the worst possible outcome. Although recent progress in gene sequencing technology has revealed the genetic profile of breast cancer including that of TNBC, the effort to understand breast cancer based on the diverse view from a more inclusive perspective is still needed (6-8).Annexin A1 (ANXA1) is a 37-kDa calcium-dependent phospholipid-linked protein belonging to the annexin superfamily and it is related to anti-inflammatory effects, regulation of cellular differentiation, proliferation and apoptosis (9-11). However, through those functions, ANXA1 is involved in tumorigenesis and the pivotal role of ANXA1 is not clearly understood. One of the main reasons for this is due to the fact that the functional role of ANXA1 in malignant tumors is quite different depending on the cancer type, such as head-and-neck, esophageal, gastric, colorectal, pancreatic, hepatic and prostate cancer (12-19). While ANXA1 is highly expressed in malignant tumors (20,21), some stu...

Homeobox A (HOXA) cluster genes, members of the HOX family, perform an important role in normal organ development. It has previously been reported that HOXA gene expression in various types of cancer is associated with poor patient outcomes. However, the role of HOXA genes, as well as their expression, in colorectal cancers (CRC) remains unknown. Therefore, the present study investigated HOXA gene expression in patients with CRC and revealed that HOXA9 expression was significantly increased in tumor tissues compared with non-tumor tissues. Additionally, the functional role of HOXA9 was assessed by knocking down the HOXA9 gene in CRC cells and by evaluating cell growth. Regarding gene expression, cases with positive HOXA9 expression (as detected by immunohistochemical staining) were significantly associated with higher TNM stage and positive lymph node metastasis, although no association was observed between increased HOXA9 levels and the rate of overall survival in the present cohort. Regarding the functional role, HOXA9 expression was demonstrated to be upregulated in patients with CRC and was associated with lymph node metastasis.

Epstein-Barr virus-positive gastric cancer [EBV (+) GC] is a distinct GC subtype with unique genetic and epigenetic aberrations. Here, we examined resected GC samples and publicly available microarray data and The Cancer Genome Atlas (TCGA) database to identify the mechanism underlying overexpression of PD-L1 in EBV (+) GC. We found that high levels of PD-L1 overexpression in EBV (+) GC were caused by focal amplification of CD274. By contrast, relatively high expression of PD-L1 in tumor tissue and infiltrating immune cells correlated with CD8 lymphocyte infiltration and IFN-γ expression via IRF3 activation. Since we reported previously that PD-L1 expression is associated both with the presence of CD8 T cells in the tumor microenvironment and with IFN-γ expression in GC, we examined a database to see whether IFN-γ-associated overexpression of PD-L1 plays a significant role in EBV (+) GC. Immunohistochemical staining showed that expression of the IRF3 signature in clinical GC samples was higher in EBV (+) than in EBV (−) cases. The data presented herein reveal a unique dual mechanism underlying PD-L1 overexpression in EBV (+) GC: high focal amplification of CD274 or IFN-γ-mediated signaling via activation of IRF3.

Kinesin family member 4A (KIF4A) is a member of the kinesin 4 subfamily of kinesin-related proteins and serves an important role in cell division. The expression levels of KIF4A have been investigated in numerous types of cancer, including cervical, lung, oral, and breast cancer, and are established to be associated with poor patient prognosis. However, the role of KIF4A, as well as its expression in colorectal cancer (CRC), remains to be elucidated. Therefore, the current study investigated KIF4A expression levels in patients with CRC and demonstrated that its levels were increased in tumor tissues compared with non-tumor tissues. To investigate the functional role of KIF4A, KIF4A was knocked down in CRC cells and cell viability was evaluated. CRC cells with KIF4A knockdown exhibited lower cell proliferation compared with control cells. In addition, KIF4A expression levels, as determined by immunohistochemistry, were compared with the expression of Ki-67, but no significant associations were observed in the patients with CRC. Therefore, KIF4A was found to be upregulated in patients with CRC and downregulation of KIF4A reduced cell proliferation in CRC cells. These results suggest that KIF4A may be a potential therapeutic target, which may improve the outcomes of patients with CRC.