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Kuang-Wen Liao

Publications and source records attributed to Kuang-Wen Liao.

8 recordsLinked to original sources
PubMed2005

Probing lectin and sperm with carbohydrate-modified quantum dots.

We report the encapsulation of quantum dots with biologically important beta-N-acetylglucosamine (GlcNAc) in different ratios, together with studies of their specific/sensitive multivalent interactions with lectins and sperm by fluorimetry, transmission electron microscopy, dynamic light scattering microscopy, confocal imaging techniques, and flow cytometry. These GlcNAc-encapsulated quantum dots (QDGLNs) specifically bind to wheat germ agglutinin, and cause fluorescence quenching and aggregation. Further studies of QDGLNs and the mannose-encapsulated QDs (QDMANs) with sperm revealed site-specific interactions, in which QDGLNs bind to the head of the sperm, while QDMANs spread over the whole sperm body.

Acetylglucosamine↗
PubMed2004

Tumor-infiltrating lymphocyte secretion of IL-6 antagonizes tumor-derived TGF-beta 1 and restores the lymphokine-activated killing activity.

IL-6 is a multifunctional cytokine that regulates cell growth, differentiation, and cell survival. Many tumor cells produce TGF-beta1, which allows them to evade CTL-mediated immune responses. IL-6 antagonizes TGF-beta1 inhibition of CD3 cell activation. However, whether IL-6 restores NK activity, which also is suppressed by TGF-beta1, is not known. We used canine transmissible venereal tumor (CTVT), which produces TGF-beta1, as a model to determine whether IL-6 restores lymphokine-activated killer (LAK) activity. During the progression phase, CTVT cells stop expressing MHC molecules. During the regression phase, the number of surface MHC molecules increases dramatically on about one-third of tumor cells. Tumor cells that stop expressing MHC should be targeted by NK cells. In this study, we found that TGF-beta1 secreted by CTVT cells suppressed LAK cytotoxicity. Interestingly, tumor-infiltrating lymphocytes (TIL) isolated from regressing CTVT secrete high concentrations of IL-6 and antagonize the anti-LAK activity of tumor cell TGF-beta1. TIL also produce IL-6 during progression phase, but the concentration is too low to block the anti-LAK activity of TGF-beta1. There is probably a threshold concentration of IL-6 needed to reverse TGF-beta1-inhibited LAK activity. In addition, in the absence of TGF-beta1, IL-6 derived from TIL does not promote the activity of LAK. This new mechanism, in which TIL manufacture high concentrations of IL-6 to block tumor TGF-beta1 anti-LAK activity, has potential applications in cancer immunotherapy and tumor prognosis.

Adjuvants, Immunologic↗
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↗
PubMed2003

Canine transmissible venereal tumor cell depletion of B lymphocytes: molecule(s) specifically toxic for B cells.

Canine transmissible venereal tumor (CTVT) is an excellent model for investigating the interaction between host immunity and tumor growth. Although CTVT is an allograft, initially the host immune system is unable to destroy the tumor cells, and the tumor grows progressively for about 4-6 months (P phase). After a short stable phase, the tumor undergoes regression (R phase). In this study, CTVT inoculation significantly reduced the proportion of B lymphocytes among all peripheral blood lymphocytes (PBL), but the proportion of B lymphocytes returned to normal after complete removal of CTVT. Following CTVT inoculation, immunoglobulin concentrations decreased gradually, coincident with B lymphocyte decline. Furthermore, CTVT secreted a soluble, heat- and protease K-sensitive cytotoxic molecule(s) that destroyed peripheral blood B lymphocytes (PBBL) but spared other types of immune cells regardless of whether mitogens, such as IL-2 or Con A, were present. The decrease in the proportion and viability of PBBL was caused by a cytotoxic molecule(s) that induced apoptosis. The molecular weight of the CTVT-derived cytotoxic molecule(s) was 30-100kDa. Human, domestic cat, horse and mouse B cells were also sensitive to the substance.

Animals↗
PubMed2003

Stable expression of chimeric anti-CD3 receptors on mammalian cells for stimulation of antitumor immunity.

Expression of CD80 or CD86 costimulatory molecules on tumor cells can produce rejection of immunogenic but not poorly immunogenic tumors. We have previously shown that anti-CD3 single-chain antibodies expressed on the surface of cells can directly activate T cells. We therefore investigated whether anti-CD3 "receptors" could enhance CD86-mediated rejection of poorly immunogenic tumors. Expression of anti-CD3 receptors on cells was increased by introduction of membrane-proximal "spacer" domains containing glycosylation sites between the single-chain antibody and the transmembrane domain of the chimeric receptors. Removal of glycosylation sites in the spacer reduced surface expression due to increased shedding of chimeric receptors from the cell surface. Induction of T-cell proliferation by anti-CD3 receptors did not correlate with the expression level of chimeric protein, but rather depended on the physical properties of the spacer. Anti-CD3 receptors effectively induced T-cell cytotoxicity, whereas coexpression with CD80 or CD86 was required for generating T-cell proliferation and IL-2 secretion. Although expression of CD86 did not significantly delay the growth of poorly immunogenic B16-F1 tumors, expression of anti-CD3 receptors with CD86 produced complete tumor rejections in 50% of mice and induced significant protection against wild-type B16-F1 tumor cells. Our results show that spacer domains can dramatically influence the surface expression and the biological activity of chimeric antibody receptors. The strong antitumor activity produced by anti-CD3 receptors and CD86 on tumor cells indicates that this strategy may be beneficial for the gene-mediated therapy of poorly immunogenic tumors.

Animals↗
PubMed2003

Identification of canine transmissible venereal tumor cells using in situ polymerase chain reaction and the stable sequence of the long interspersed nuclear element.

Canine transmissible venereal tumor (CTVT) is a unique tumor that can be transplanted across the major histocompatibility complex (MHC) barrier by viable tumor cells. In dogs, CTVT grows progressively for a few months and then usually regresses spontaneously. A long interspersed nuclear element (LINE) insertion is found specifically and constantly in the 5' end of the CTVT cell c-myc gene, outside the first exon. The rearranged LINE-c-myc gene sequence has been used with polymerase chain reaction (PCR) to diagnose CTVT. However, in CTVT cells, the total length of the inserted LINE gene is not constant. In this experiment, variation in the inserted LINE gene was studied to determine which parts of the LINE sequence can be used as primers to identify CTVT cells with in situ PCR (IS PCR). The LINE gene was inserted between the TATA boxes in the promoter region of c-myc. In CTVT cells, deletions of different lengths are frequent in this gene. However, the 550-bp segment at the 5' end of the LINE-c-myc gene was stable. Thus, primers were designed to cover the stable 0.55-kb segment from the 5' end outside the first exon of the c-myc gene to the 5' end of LINE gene stable segment. With these primers and IS PCR, individual CTVT cells in formalin-fixed tissue sections and CTVT cultures were identified. Cells from other canine tumors were negative for this gene. In addition, the CTVT-specific, 0.55-kb segment was not found in any spindle-shaped cells from progressive or regressive phase CTVT. The IS PCR technique also did not detect any positive spindle-shaped cells in CTVT cell cultures. Thus, fibroblastic terminal differentiation is less likely to be a mechanism for spontaneous regression of CTVT cells.

Animals↗
PubMed2002

Effect of tumor infiltrating lymphocytes on the expression of MHC molecules in canine transmissible venereal tumor cells.

Canine transmissible venereal tumor (CTVT) can be allo-transplanted across major histocompatibility complex barriers. The expression of MHC molecules is usually low in the progression (P) stage and then greatly increases during tumor regression (R). We investigated the effects of tumor infiltrating lymphocytes (TIL) on the expression of MHC molecules of CTVT cells. Isolated, viable CTVT cells were inoculated at each of 12 sites (1 x 10(8) CTVT cells per site) on the back of six, mixed-breed dogs. Tumor masses were collected every 2-3 weeks and prepared for histopathologic, immunocytochemistry, flow cytometry and immunoblotting studies. The level of MHC expression on tumor cells from different stages of growth was measured. Initially, expression of MHC I and II molecules in P phase CTVT was low. Twelve weeks post-inoculation (PI), expression increased dramatically and it continued to increase during R phase. Tumor growth slowed after 12 weeks PI and tumors entered R phase around 17 weeks PI. We hypothesize that CTVT evades host immunosurveillance and grows progressively for 12 weeks, when it becomes vulnerable and subject to the host's anti-tumor immune responses. We further demonstrated that R phase, but not P phase, TIL were closely associated with the over-expression of MHC I and II molecules by CTVT cells. The number and proportion of TIL were higher in R phase tumors. Supernatants, from R phase co-cultures (CTVT+TIL) and TIL only, promoted MHC I and II expression on P phase CTVT cells. After culturing alone for 1 month, expression of MHC classes I and II molecules in R phase CTVT cells decreased to the level of P phase CTVT cells. However, the above-mentioned supernatants restored their expression of MHC I and II molecules. In contrast, supernatants from P phase TIL or CTVT cells increased expression slightly or had no effect. Therefore, TIL, not CTVT cells, produce the effective substance (s) to promote the expression of MHC molecules by the tumor cells. Heat treated supernatant was unable to promote the expression of MHC I and II molecules by CTVT cells. In conclusion, TIL isolated from R phase CTVT secreted a heat-sensitive, soluble substance(s) that triggered over-expression of MHC I and II after 12 weeks PI. This caused the tumor to enter R phase and helped stop CTVT growth. Our findings will facilitate the understanding and further investigation of the mechanisms that initiate host immune surveillance against tumors.

Animals↗