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. In the present study, we investigated the expression of anxa1 in gastric and colon cancer, and analyzed the relationship between ANXA1 expression and clinicopathological factors. anxa1 mrna expression in gastric and colon cancer tissues was not significantly changed compared to that in normal tissues. When anxa1 protein expression was evaluated by immunohistochemical staining, ANXA1 expression was observed in 76 of 135 cases of gastric cancer (56.3%), and correlations were found between ANXA1 expression and depth of wall invasion (P<0.001), lymphatic invasion (P=0.023), venous invasion (P=0.002), lymph node metastasis (P=0.001) and UICC stage (P<0.001). Disease-specific survival rate was significantly lower in cases with ANXA1 expression compared to that in cases without (P=0.0053). In colon cancer, ANXA1 expression was detected in 61 of 210 cases (29.0%) and correlations were found with gender (P=0.038), lymphatic invasion (P=0.011), venous invasion (P=0.023), lymph node metastasis (P=0.042) and UICC stage (P=0.041). The disease-specific survival rate tended to be lower in cases with ANXA1 expression, although the differences were not statistically significant (P=0.6984). Our results indicate that up-regulated ANXA1 expression is involved in cancer invasion and lymph node metastasis. Furthermore, high levels of anxa1 expression were implicated in poor prognosis of patients. ANXA1 may be applicable as a prognostic biomarker in gastric and colon cancer, and a potential target for treatment.

Ubiquitin-like with PHD and ring-finger domain 1 (UHRF1) binds to methylated promoters of a number of tumor-suppressor genes, including p16INK4A and p14ARF, by forming complexes with DNA methyltransferases and HDAC1, resulting in the induction of carcinogenesis. Altered UHRF1 expression has been demonstrated in various types of cancers. Previous reports indicate that UHRF1 expression is regulated by E2F-1 expression. We investigated UHRF1 expression using immunohistochemical staining in 231 colorectal cancer and 40 adenoma specimens, analyzed the relationship between UHRF1 expression and clinicopathological findings and the association between UHRF1 and E2F-1 expression. To better understand the biological function of UHRF1 in colorectal cancer, knockdown of UHRF1 expression was performed using siRNA methods. High UHRF1 expression was observed in 152 of 231 (65.8%) colorectal cancer patients, and was detected in 35 of 40 adenoma specimens samples (87.5%). UHRF1 staining was detected in the nucleus of cancer cells, while it was not detected in colonic normal mucosa. High UHRF1 expression was significantly observed in right compared with left hemicolon cancer (p=0.008). Moreover, high UHRF1 expression tended to be associated with depth of invasion (p=0.051). UHRF1 expression was significantly associated with E2F-1 expression (p<0.0001). Knockdown of UHRF1 expression suppressed cellular growth in colon cancer cell lines, HCT116 and SW620. In conclusion, we demonstrated that UHRF1 expression was upregulated in approximately two-thirds of colorectal cancer specimens and was particularly expressed in right compared with left hemicolon cancer. Moreover, knockdown of UHRF1 expression induced growth inhibition in colon cancer cell lines. UHRF1 may be involved in cellular proliferation and molecular pathogenesis of colorectal cancer in the right hemicolon.

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.

Although having the capacity to grow in response to a stimulus that perturbs the pituitary-thyroid axis, the thyroid gland is considered not a regenerative organ. In this study, partial thyroidectomy (PTx) was used to produce a condition for thyroid regeneration. In the intact thyroid gland, the central areas of both lobes served as the proliferative centers where microfollicles, and bromodeoxyuridine (BrdU)-positive and/or C cells, were localized. Two weeks after PTx, the number of BrdU-positive cells and cells with clear or faintly eosinophilic cytoplasm were markedly increased in the central area and continuous to the cut edge. Clear cells were scant in the cytoplasm, as determined by electron microscopy; some retained the characteristics of calcitonin-producing C cells by having neuroendocrine granules, whereas others retained follicular cell-specific features, such as the juxtaposition to a lumen with microvilli. Some cells were BrdU-positive and expressed Foxa2, the definitive endoderm lineage marker. Serum TSH levels drastically changed due to the thyroidectomy-induced acute reduction in T(4)-generating tissue, resulting in a goitrogenesis setting. Microarray followed by pathway analysis revealed that the expression of genes involved in embryonic development and cancer was affected by PTx. The results suggest that both C cells and follicular cells may be altered by PTx to become immature cells or immature cells that might be derived from stem/progenitor cells on their way to differentiation into C cells or follicular cells. These immature clear cells may participate in the repair and/or regeneration of the thyroid gland.