Biomedical subjects

Wenhua Lang

Publications and source records attributed to Wenhua Lang.

4 recordsLinked to original sources

PubMed2006

Down-regulation of hepatoma-derived growth factor inhibits anchorage-independent growth and invasion of non-small cell lung cancer cells.

We recently reported that a high level of hepatoma-derived growth factor (HDGF) expression in tumors correlates with a high incidence of tumor relapse or distant metastasis and shortened survival time in patients with non-small cell lung cancer (NSCLC). However, the mechanisms of the HDGF-associated aggressive biological behavior are unknown. In this study, we knocked down HDGF expression in NSCLC cells to determine the biological consequences. Transfection with HDGF-specific small interfering RNA (siRNA) resulted in down-regulation of HDGF expression in four NSCLC cell lines. Down-regulation of HDGF resulted in no detectable effect on anchorage-dependent cell growth as determined with a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, a microelectronic cell sensor system, and flow cytometry. In contrast, cells transfected with HDGF-siRNA grew more slowly and formed significantly fewer colonies in soft agar than did cells treated with LipofectAMINE alone or transfected with negative control siRNA. In an in vitro invasion assay, significantly fewer cells transfected with HDGF-siRNA than cells treated with LipofectAMINE alone were able to invade across a Matrigel membrane barrier. In an in vivo mouse model, A549 cells treated with HDGF-siRNA grown significantly slower than the cells treated with LipofectAMINE alone or negative control siRNA. Morphologically, HDGF-siRNA-treated tumors exhibited markedly reduced blood vessel formation and increased necrosis, whereas the Ki67 labeling indices were similar in tumors treated with controls. Our results suggest that HDGF is involved in anchorage-independent growth, cell invasion, and formation of neovasculature of NSCLC. These qualities may contribute to the HDGF-associated aggressive biological behavior of NSCLC.

Animals↗

PubMed2006

Tissue-specific function of lymph node fibroblastic reticulum cells.

OBJECTIVE: We present the first characterization of the cytokine expression pattern of lymph node fibroblastic reticulum cells (FRC), which are the stromal cells responsible for maintaining the highly structured nodal reticular fiber framework. METHODS: Microarray expression profiles of cultured nodal FRC and dermal fibroblasts (DF) were compared as well as their response to TNF, IL-4, IL-6 and IL-13, cytokines responsible for intranodal stromal activation. RESULTS: Hierarchical clustering of FRC and DF short-term culture samples revealed genes that were differentially expressed in FRC and DF. Identified differently regulated genes were confirmed by RNase protection analysis, PCR or immunohistochemistry. At earlier culture time points, FRC showed higher levels of several chemokines, including CCL2/MCP-1, and cytokines, e.g. IL-6, whereas several genes related to the production of extracellular matrix and angiogenesis were preferentially expressed in early DF cultures. By 60 days in culture, FRC and DF showed similar expression patterns consistent with homogenization of specialized stromal subsets. FRC and DF showed nearly identical transcriptional responses to exogenous TNF stimulation. CONCLUSIONS: Cultured FRC showed an overall transcriptional profile similar to cultured DF, including parallel responsiveness to TNF, but with differences in the expression of chemotactic chemokines, which reflect their biological roles.

Cells, Cultured↗

PubMed2004

Cooperation between PKC-alpha and PKC-epsilon in the regulation of JNK activation in human lung cancer cells.

Phorbol esters can induce activation of two mitogen-activated protein kinase (MAPK) pathways, the extracellular signal-regulated kinase (ERK) pathway and the c-Jun N-terminal kinase (JNK) pathway. Unlike ERK activation, JNK activation by phorbol esters is somehow cell-specific. However, the mechanism(s) that contribute to the cell-specific JNK activation remain elusive. In this study, we found that phorbol 12-myristate 13-acetate (PMA) induced JNK activation only in non-small cell lung cancer (NSCLC) cells, but not in small cell lung cancer (SCLC) cells, whereas ERK activation was detected in both cell types. In NSCLC cells, PMA induced JNK activation in a time- and dose-dependent manner. JNK activation was attenuated by protein kinase C (PKC) down-regulation through prolonged pre-treatment with PMA and significantly inhibited by PKC inhibitors Gö6976 and GF109203X. Subcellular localization studies demonstrated that PMA induced translocation of PKC-alpha, -betaII, and -epsilon isoforms, but not PKC-delta, from the cytosol to the membrane. Analysis of various PKC isoforms revealed that PKC-epsilon was exclusively absent in the SCLC cell lines tested. Ectopic expression of PKC-epsilon in SCLC cells restored PMA activation of JNK signaling only in the presence of PKC-alpha, suggesting that PKC-alpha and PKC-epsilon act cooperatively in regulating JNK activation in response to PMA. Furthermore, using dominant negative mutants and pharmacological inhibitors, we define that a putative Rac1/Cdc42/PKC-alpha pathway is convergent with the PKC-epsilon/MEK1/2 pathway in terms of the activation of JNK by PMA.

Animals↗

PubMed2002

Protein kinase C-epsilon promotes survival of lung cancer cells by suppressing apoptosis through dysregulation of the mitochondrial caspase pathway.

The serine/threonine protein kinase C (PKC) has been implicated in the regulation of drug resistance and cell survival in many types of cancer cells. However, the one or more precise mechanisms remain elusive. In this study, we have identified and determined the mechanism by which PKC-epsilon, a novel PKC isoform, modulates drug resistance in lung cancer cells. Western blot analysis demonstrates that expression of PKC-epsilon, but not other PKC isoforms, is associated with the chemo-resistant phenotype of non-small cell lung cancer (NSCLC) cell lines. Northern blotting and nuclear run-on transcription analysis further reveals that the failure of expression of PKC-epsilon in the chemo-sensitive phenotype of small cell lung cancer (SCLC) cells results from transcriptional inactivation of the gene. Importantly, forced expression of PKC-epsilon in NCI-H82 human SCLC cells confers a significant resistance to the chemotherapeutic drugs, etoposide and doxorubicin. Resistance is characterized by a significant reduction in apoptosis in PKC-epsilon-expressing cells. Treatment of NCI-H82 cells with etoposide induces a series of time-dependent events, including the release of cytochrome c from the mitochondria to the cytosol, activation of caspase-9 and caspase-3, and cleavage of poly(ADP-ribose) polymerase (PARP). All of these events are blocked by PKC-epsilon expression. Furthermore, caspase-specific inhibitors, z-VAD-fmk and z-DEVD-fmk, significantly attenuate the accumulation of sub-G(1) population and block the PARP cleavage in response to etoposide. These results suggest that PKC-epsilon prevents cells from undergoing apoptosis through inhibition of the mitochondrial-dependent caspase activation, thereby leading to cell survival. Finally, down-regulation of PKC-epsilon expression by the antisense cDNA in NSCLC cells results in increased sensitivity to etoposide. Taken together, our findings suggest an important role for PKC-epsilon in regulating survival of lung cancer cells.

Antineoplastic Agents↗