Biomedical subjects

Chiu-Min Cheng

Publications and source records attributed to Chiu-Min Cheng.

4 recordsLinked to original sources

PubMed2005

Pigmentation in basal cell carcinoma involves enhanced endothelin-1 expression.

Basal cell carcinoma (BCC) is the most prevalent malignant skin tumor. In Asian patients, marked pigmentation in BCC lesions is often observed. Recently, endothelins (ETs) have been implicated to participate in the pigmentation process of BCC. Therefore, we set out to investigate the involvement of ET in the pigmentation process of BCC and the potential regulators in the pigmentation pathway. We explored the effects of an established BCC cell line on melanocytes. The growth factor profiles of BCC culture supernatant and effects of supernatant on melanocytes were documented. Potential regulators involved in the pigmentation pathway were also studied. The immunohistochemical staining of pigmented and non-pigmented BCC specimens was performed to confirm our in vitro findings. Our results showed that BCC supernatant contained significant amount of ET-1, basic fibroblast growth factor, and nerve growth factor. Furthermore, BCC supernatant stimulated melanin formation of cultured melanocytes. Addition of ET-receptor antagonist abrogated the melanogenic effect of BCC supernatant on melanocytes. Introduction of UVB irradiation decreased the ET-1 secretion by BCC cells. Immunohistochemical staining of the pigmented facial BCC specimens showed prominent expression of ET-1 on pigmented BCC, while the non-pigmented facial BCC specimens showed little ET-1 reactivity. Tumor necrosis factor-alpha (TNF-alpha) staining showed little expression on BCC specimens, regardless of pigmentation status. In summary, our results indicate that enhanced ET-1 expression in pigmented BCC plays an important role in the hyperpigmentation of this tumor. Moreover, this enhanced ET-1 cascade showed little correlation with UV irradiation and TNF-alpha expression in our study.

Basal Cell Carcinoma↗

PubMed2004

Hapten-directed targeting to single-chain antibody receptors.

Artificial recombinant receptors may be useful for selectively targeting imaging and therapeutic agents to sites of gene expression. To evaluate this approach, we developed transgenes to express highly on cells a single-chain antibody (scFv) against the hapten 4-ethoxymethylene-2-phenyl-2-oxazoline-5-one (phOx). A phOx enzyme conjugate was created by covalently attaching phOx molecules to polyethylene glycol (PEG)-modified beta-glucuronidase. Cells expressing phOx scFv but not control scFv receptors were selectively killed after exposure to ss-glucuronidase derivatized with phOx and PEG (phOx-beta G-PEG) and a glucuronide prodrug (p-hydroxy aniline mustard beta-D-glucuronide, HAMG) of p-hydroxyaniline mustard. Targeted activation of HAMG produced bystander killing of receptor-negative cells in mixed populations containing as few as 10% phOx-receptor-positive cells. Functional phOx scFv receptors were stably expressed on B16-F1 melanoma tumors in vivo. Treatment of mice bearing established phOx-receptor-positive tumors with phOx-beta G-PEG and HAMG significantly (P< or =.0005) suppressed tumor growth as compared with treatment with beta G-PEG and HAMG or prodrug alone. phOx was unstable in the serum, suggesting alternative haptens may be more suitable for in vivo applications. Our results show that therapeutic agents can be targeted to artificial hapten receptors in vitro and in vivo. The expression of artificial receptors on target cells may allow preferential delivery of therapeutic or imaging molecules to sites of transgene expression.

Aniline Mustard↗

PubMedDate not supplied

Monoclonal antibody-based quantitation of poly(ethylene glycol)-derivatized proteins, liposomes, and nanoparticles.

Covalent attachment of poly(ethylene glycol) (PEG) molecules to drugs, proteins, and liposomes is a proven technology for improving their bioavailability, safety, and efficacy. Qualitative and quantitative analysis of PEG-derivatized molecules is important for both drug development and clinical applications. We previously reported the development of a monoclonal IgM antibody (AGP3) to PEG. We now describe a new IgG1 monoclonal antibody (E11) to PEG and show that it can be used in combination with AGP3 to detect and quantify PEG-derivatized molecules. Both antibodies bound the repeating subunits of the PEG backbone and could detect free PEG and PEG-modified proteins by ELISA, immunoblotting, and flow cytometry. Detection sensitivity increased with the length and the number of PEG chains on pegylated molecules. Both antibodies also efficiently accelerated the clearance of a PEG-modified enzyme in vivo. A sandwich ELISA in which E11/AGP3 were employed as the capture/detection antibodies was developed to detect PEG-modified proteins at concentrations as low as 1.2 ng/mL. In addition, the ELISA could also quantify, in the presence of 10% fetal bovine serum, free methoxy-PEG20,000, PEG2,000-quantum dots, and PEG2,000-liposomes at concentrations as low as 20 ng/mL (1.0 nM), 1.4 ng/mL (3.1 pM), and 2.4 ng/mL (3.13 nM phospholipids), respectively. Finally, we show that the sandwich ELISA could accurately measured the in vivo half-life of a PEG-modified enzyme. These antibodies should be generally applicable to the qualitative and quantitative analysis of all PEG-derivatized molecules.

Animals↗

PubMedDate not supplied

Combination cancer therapy by hapten-targeted prodrug-activating enzymes and cytokines.

Combination therapy can help overcome limitations in the treatment of heterogeneous tumors. In the current study, we examined whether multiple therapeutic agents could be targeted to anti-dansyl single-chain antibodies (DNS scFv) that were anchored on the plasma membrane of cancer cells. Functional DNS scFv could be stably expressed on CT-26 colon cancer cells both in vitro and in vivo. Dansyl moieties were covalently attached to recombinant beta-glucuronidase (betaG) and interleukin 2 (IL-2) via a flexible poly(ethylene glycol) linker to form DNS-PEG-betaG and DNS-PEG-IL-2 conjugates. The conjugates displayed enzymatic and splenocyte-stimulatory activities, respectively, that were similar to those of the unmodified proteins. The conjugates selectively bound CT-26 cells that expressed anti-DNS scFv (CT-26/DNS cells) but not CT-26 cells that expressed control scFv (CT-26/phOx cells). DNS-PEG-betaG preferentially activated a glucuronide prodrug (BHAMG) of p-hydroxy aniline mustard at CT-26/DNS cells in culture and accumulated in subcutaneous CT-26/DNS tumors after intravenous administration. Systemic administration of DNS-PEG-IL-2 or DNS-PEG-betaG and BHAMG significantly delayed the growth of CT-26/DNS but not control CT-26/phOx tumors. Combination treatment with DNS-PEG-betaG and BHAMG followed by DNS-PEG-IL-2 therapy significantly suppressed the growth of CT-26/DNS tumors as compared to either single-agent regimen. These results show that at least two DNS-modified therapeutic agents can be selectively delivered to DNS scFv receptors in vitro and in vivo, allowing combination therapy of DNS scFv-modified tumors.

Animals↗