YES1 activation induces acquired resistance to neratinib in HER2‐amplified breast and lung cancers

Molecular‐targeted therapies directed against human epidermal growth factor receptor 2 (HER2) are evolving for various cancers. Neratinib is an irreversible pan‐HER tyrosine kinase inhibitor and has been approved by the FDA as an effective drug for HER2‐positive breast cancer. However, acquired resistance of various cancers to molecular‐targeted drugs is an issue of clinical concern, and emergence of resistance to neratinib is also considered inevitable. In this study, we established various types of neratinib‐resistant cell lines from HER2‐amplified breast and lung cancer cell lines using several drug exposure conditions. We analyzed the mechanisms of emergence of the resistance in these cell lines and explored effective strategies to overcome the resistance. Our results revealed that amplification of YES1, which is a member of the SRC family, was amplified in two neratinib‐resistant breast cancer cell lines and one lung cancer cell line. Knockdown of YES1 by siRNA and pharmacological inhibition of YES1 by dasatinib restored the sensitivity of the YES1‐amplified cell lines to neratinib in vitro. Combined treatment with dasatinib and neratinib inhibited tumor growth in vivo. This combination also induced downregulation of signaling molecules such as HER2, AKT and MAPK. Our current results indicate that YES1 plays an important role in the emergence of resistance to HER2‐targeted drugs, and that dasatinib enables such acquired resistance to neratinib to be overcome.     

Effects of Actinomyces and Fusobacterium on humoral immune response in vitro

The purpose of this study was to examine the effects of Actinomyces viscosus and Fusobacterium nucleatum sonicates on antibody formation in vitro and to elucidate their mechanisms on the cellular basis. Suspensions of A. viscosus and F. nucleatum were sonicated, and the supernatant was filtered and heated. After AKR mouse spleen cells were stimulated with sheep red blood cells, the antibody formation was assayed by counting the plaque-forming cells (PFC). Macrophages, T- and B-cells were harvested from the mouse peritoneal exudate and spleen. Mitogenicity of the sonicates was determined by counting the uptake of ³H-thymidine.
The PFC number, when A. viscosus or F. nucleatum sonicate was added, increased significantly by 2.4–6.6 times more than the control. Two sonicates were found to activate the macrophages, resulting in an increase of PFC.
F. nucleatum sonicate was effective to PFC response via activation of helper T-cells. Stimulation index of F. nucleatum sonicate on T-cells was 4.1 and that of A. viscosus sonicate on B-cells was 3.2. In conclusion, the enhanced antibody formation by A. viscosus sonicate depends on the activation of macrophages and B-cell mitogenicity, and the F. nucleatum sonicate enhances the PFC response by activation of both macrophages and helper T-cells and by T-cell proliferation.     

The correlation of histologic features with a panoramic radiography pattern and a computed tomography pattern of bone destruction in carcinoma of the mandibular gingiva

OBJECTIVE: We sought to clarify the correlation among a computed tomography (CT) or a panoramic radiography (PR) pattern of bone destruction, a histologic pattern of bone destruction, and a mode of invasion in carcinoma of the mandibular gingiva. STUDY DESIGN: CT images, panoramic radiographs, and decalcified, hematoxylin-eosin-stained preparations of the excised mandibular bone of 62 patients with carcinoma of the mandibular gingiva were retrospectively evaluated. Each computed tomograph, panoramic radiograph, and the histologic pattern of bone destruction was classified as 1 of 5 types: erosive, erosive and partly mixed, mixed, mixed and partly invasive, or invasive. The mode of invasion of the tumor was also assessed with a hematoxylin-eosin-stained preparation of the initial biopsy specimen. The relationships among the CT pattern, the PR pattern, the histologic pattern of bone destruction, and the mode of invasion of the tumor were statistically analyzed by using the Spearman rank correlation test. RESULTS: The CT pattern (P =.005) and the PR pattern (P =.003) were significantly correlated with the histologic pattern with respect to the bone destruction. The CT pattern (P =.996), the PR pattern (P =.997), and the histologic pattern (P =.521) of bone destruction were not correlated with the mode of invasion seen in the biopsy specimen. CONCLUSION: The CT pattern and the PR pattern of bone destruction reflect the histologic pattern of bone destruction caused by carcinoma of the mandibular gingiva but are not associated with the mode of invasion of the tumor.     

A Hepatocyte Growth Factor (HGF)/receptor autocrine loop regulates constitutive self-renewal of human periodontal ligament cells but reduces sensitivity to exogenous HGF

BACKGROUND: In addition to its prominent role in liver regeneration, hepatocyte growth factor (HGF) is now generally thought to be produced by mesenchymal cells to promote the regeneration of epithelial tissue by a paracrine mechanism. However, it is not known how or if HGF could be involved in the regeneration of periodontal tissues. The purpose of this study was to characterize the ability of normal human periodontal ligament (PDL) cells to produce or respond to HGF. METHODS: PDL cells derived from healthy young volunteers were used from passages four through 10. HGF receptors were detected both by immunocytochemical staining and Western-blotting analysis. Both DNA synthesis (by bromo-deoxyuridine [BrdU]-incorporation) and secreted HGF were quantified by enzyme-linked immunosorbent assays. Mitogen-activated protein kinase (MAPK) phosphorylation was also analyzed by Western blot. RESULTS: Despite the immunocytochemical demonstration of HGF receptor protein in the cytoplasm and on the plasma membrane of PDL cells, exogenous recombinant human HGF did not exert the mitogenic effects expected. As reported for other mesenchymal cells, PDL cells were found to secrete HGF. Treatments with neutralizing anti-HGF antibody significantly suppressed constitutive PDL cell proliferation and sustained the receptor protein at higher levels than in non-treated cells. Under these conditions, exogenous HGF rapidly phosphorylated extracellular signal-regulated kinase (ERK), an action linked to the cell proliferation and downregulation of cell-surface receptors. CONCLUSIONS: Unlike other known mesenchymal or epithelial cells, these findings suggest that normal PDL cells from young donors possess a constitutive HGF/receptor autocrine loop that normally regulates their replacement self-proliferation but reduces sensitivity to exogenously applied HGF by acute receptor downregulation.     

Effects of Nd:YAG and CO2 laser treatment and ultrasonic scaling on periodontal pockets of chronic periodontitis patients

BACKGROUND: The aim of the present study was to compare the effectiveness of Nd:YAG and CO2 laser treatment to that of ultrasonic scaling used as monotherapies by examining clinical parameters, subgingival microflora, and interleukin-1 beta (IL-1beta) in gingival crevicular fluid (GCF). METHODS: Eighteen patients, each of whom had 2 or more sites with probing depth measuring > 5 mm, were included this clinical trial. The 41 sites were randomly assigned treatment with either Nd:YAG laser alone (n = 14, 100 mj, 20 pps, 2.0 W, 120 seconds), CO2 laser alone (n = 13, 2.0 W, 120 seconds), or ultrasonic scaling alone (n = 14, maximum power, 120 seconds). At baseline and at 1, 4, and 12 weeks, clinical measurements (plaque index, PI; gingival index, GI; probing depth, PD; clinical attachment level, CAL; and bleeding on probing, BOP) were performed and subgingival plaque and GCF sampled. A quantitative analysis of Porphyromonas gingivalis was carried out using real-time polymerase chain reaction (PCR) procedures. The amounts of IL-1beta were estimated by an enzyme-linked immunosorbent assay (ELISA). RESULTS: Decreased inflammation and PD were observed in all 3 groups after treatment. A microbiological analysis indicated significant decreases in P. gingivalis in the Nd:YAG and scaling groups at 1, 4, and 12 weeks compared to baseline (P < 0.05). The amount of GCF significantly decreased in the Nd:YAG and scaling groups at 12 weeks. The amount of IL-1beta increased in the CO2 group from baseline to 1 week (P < 0.05). The Nd:YAG group tended to show a decrease in IL-1beta from 1 to 12 weeks, although these data were not statistically significant. CONCLUSIONS: Our data suggest that Nd:YAG laser and ultrasonic scaling treatments showed significant improvements regarding the clinical parameters and subgingival microflora compared to the baseline, but no significant difference was observed between the 3 groups.