Solomon F. Ofori-Acquah

Activated leukocyte cell adhesion molecule in breast cancer: prognostic indicator

IntroductionActivated leukocyte cell adhesion molecule (ALCAM) (CD166) is an immunoglobulin molecule that has been implicated in cell migration. The present study examined the expression of ALCAM in human breast cancer and assessed its prognostic value.MethodsThe immunohistochemical distribution and location of ALCAM was assessed in normal breast tissue and carcinoma. The levels of ALCAM transcripts in frozen tissue (normal breast, n = 32; breast cancer, n = 120) were determined using real-time quantitative PCR. The results were then analyzed in relation to clinical data including the tumor type, the grade, the nodal involvement, distant metastases, the tumor, node, metastasis (TNM) stage, the Nottingham Prognostic Index (NPI), and survival over a 6-year follow-up period.ResultsImmunohistochemical staining on tissue sections in ducts/acini in normal breast and in breast carcinoma was ALCAM-positive. Differences in the number of ALCAM transcripts were found in different types of breast cancer. The level of ALCAM transcripts was lower (P = 0.05) in tumors from patients who had metastases to regional lymph nodes compared with those patients without, in higher grade tumors compared with Grade 1 tumors (P < 0.01), and in TNM Stage 3 tumors compared with TNM Stage 1 tumors (P < 0.01). Tumors from patients with poor prognosis (with NPI > 5.4) had significantly lower levels (P = 0.014) of ALCAM transcripts compared with patients with good prognosis (with NPI < 3.4), and tumors from patients with local recurrence had significantly lower levels than those patients without local recurrence or metastases (P = 0.04). Notably, tumors from patients who died of breast cancer had significantly lower levels of ALCAM transcripts (P = 0.0041) than those with primary tumors but no metastatic disease or local recurrence. Patients with low levels of ALCAM transcripts had significantly (P = 0.009) more incidents (metastasis, recurrence, death) compared with patients with primary breast tumors with high levels of ALCAM transcripts.ConclusionsIn the present panel of breast cancer specimens, decreased levels of ALCAM correlated with the nodal involvement, the grade, the TNM stage, the NPI, and the clinical outcome (local recurrence and death). The data suggest that decreased ALCAM expression is of clinical significance in breast cancer, and that reduced expression indicates a more aggressive phenotype and poor prognosis.

Activated leukocyte cell adhesion molecule is a component of the endothelial junction involved in transendothelial monocyte migration.

Transendothelial leukocyte migration is a major aspect of the innate immune response. It is essential in repair and regeneration of damaged tissues and is regulated by multiple cell adhesion molecules (CAMs) including members of the immunoglobulin (Ig) superfamily. Activated leukocyte cell adhesion molecule (ALCAM/CD166) is an Ig CAM expressed by activated monocytes and endothelial cells. Hitherto, the functional relevance of ALCAM expression by endothelial cells and activated monocytes remained unknown. In this report, we demonstrate soluble recombinant human ALCAM significantly inhibited the rate of transendothelial migration of monocyte cell lines. Direct involvement of ALCAM in transendothelial migration was evident from the robust inhibition of this process by ALCAM blocking antibodies. However, soluble recombinant ALCAM had no impact on monocyte migration or adhesion to endothelium. Localization of ALCAM specifically at cell–cell junctions in endothelial cells supported its role in transendothelial migration. This study is the first to localize ALCAM to endothelial cell junctions and demonstrate a functional relevance for co‐expression of ALCAM by activated monocytes and endothelial cells.

p38 MAP kinase activation mediates γ-globin gene induction in erythroid progenitors

Abstract Objective Our goal was to determine the role of p38 mitogen-activated protein kinase (MAPK) signaling in fetal hemoglobin (HbF) induction. Two histone deacetylase inhibitors (HDAIs), sodium butyrate (NB), and trichostatin (TSA) and hemin were analyzed. In addition, the effect of direct activation of p38 MAPK on γ-globin gene activity was studied. Method Primary erythroid progenitors derived from peripheral blood mononuclear cell and K562 erythroleukemia cells were analyzed. Cells were grown in NB, TSA, hemin, or anisomycin either alone or in the presence of the p38 MAPK inhibitor SB203580. The effects of the various treatments on γ-globin RNA, HbF, and phosphorylated p38 MAPK levels were measured by RNase protection assay, alkaline denaturation, and Western blot analysis, respectively. A K562 stable line overexpressing constitutively active p38 MAPK was established using MAPK kinase kinase 3 (MKK3) and MKK6, the immediate upstream activators of p38. The direct effect of p38 MAPK overexpression on γ-globin mRNA synthesis was analyzed. Results NB and TSA activated p38 MAPK and increased γ-globin mRNA levels in K562 cells and primary erythroid progenitors. Pretreatment with SB203580 blocked p38 MAPK and γ-globin gene activation. In contrast, no change in p38 activity was observed with hemin inductions. Direct activation of p38 by anisomycin or constitutive overexpression also increased γ-globin mRNA in the absence of HbF inducers in wild-type K562 cells and in the MKK stable lines. Conclusion This study supports a novel role for p38 MAPK in γ-globin regulation in human erythroid progenitors.