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Biomedical subjects

Geng Li

Publications and source records attributed to Geng Li.

13 recordsLinked to original sources
PubMed2025

The R203M and D377Y mutations of the nucleocapsid protein promote SARS-CoV-2 infectivity by impairing RIG-I-mediated antiviral signaling.

The viral protein mutations can modify virus-host interactions during virus evolution, and thus alter the extent of infection or pathogenicity. Studies indicate that nucleocapsid (N) protein of SARS-CoV-2 participates in viral genome assembly, intracellular signal regulation and immune interference. However, its biological function in viral evolution is not well understood. SARS-CoV-2 N protein mutations were analyzed in Delta, Omicron, and original strains. Two mutations with a methionine (M) residue at site 203 and a tyrosine (Y) residue at site 377 of the N protein were found in Delta strain but not in Omicron and original strains, and promoted SARS-CoV-2 infection therein. Those mutations, R203M and D377Y, enhanced the inhibitory impact of N protein on the impairment of RIG-I-mediated antiviral signaling, such as IRF3 phosphorylation and IFN-β activation. The viral RNA-binding activity of N protein was promoted by these mutations, effectively attenuating the recognition and interaction of RIG-I with viral RNA compared to the original or other variants. The R203M/D377Y mutations thus enhanced the suppressive activity of the N protein on RIG-I-mediated interferon induction both in vitro and in vivo, which in turn promoted viral replication. This study helps to understand the variability of SARS-CoV-2 in regulating host immunity.

SARS-CoV-2↗
PubMed2003

Disabled infectious single cycle herpes simplex virus (DISC-HSV) is a candidate vector system for gene delivery/expression of GM-CSF in human prostate cancer therapy.

BACKGROUND: DISC-HSV is a replication incompetent herpes simplex virus that is a highly efficient vector for the transduction of genes in vivo and in vitro. We examine the ability of DISC-HSV to infect human prostate cancer cell-lines and xenograft tumor models, and induce expression of reporter and therapeutic cytokine genes. METHODS: Infection was confirmed by cellular staining for the beta-galactosidase reporter gene product, and by EM. Human GM-CSF production following DISC-hGMCSF infection was measured using ELISA. The metabolic activity of infected cells was determined by NADP/NADPH assay. Cell death was estimated by cell-cycle analysis using flow cytometry with propidium iodide staining. RESULTS: Infection of DU145, PC3 and LNCaP cells with DISC-HSV was dose dependent. Cells infected with DISC-hGM-CSF released significant levels of hGM-CSF for 3 days. NADP/NADPH assay suggested that infected cells continued to be metabolically active for 3 days post-infection, which was consistent with flow cytometry findings that cell death did not occur within 7 days of infection. Tumor xenografts injected with DISC-HSV expressed beta-galactosidase, and intracellular viral particles were demonstrated using EM. CONCLUSIONS: We have previously reported the rejection of established tumors following intra-tumoral injection of DISC-GMCSF. This study demonstrates the ability of DISC-HSV to infect prostate cancer and express GMCSF at significant levels. We suggest that prostate cancer is a potential target for therapy using DISC-HSV containing GM-CSF.

Animals↗
PubMed2003

Visual cortical activations on fMRI upon stimulation of the vision-implicated acupoints.

We used fMRI to reveal the visual cortical activations during conventional or electro-acupuncture over four vision-implicated acupoints in 18 healthy volunteers and compared the results with those obtained during direct visual stimulation. Positive activations were seen over the visual cortex during visual stimulation in all subjects, and similar activations were observed in 10 subjects during conventional acupuncture as well as in eight and seven subjects during electro-acupuncture at 2 and 20 Hz, respectively. Negative activations were also seen over the occipital lobes, temporal gyri and frontal gyri bilaterally in 13 subjects during conventional acupuncture. Thus, acupuncture may modulate the activity of relevant brain sites. Our results also suggest that electro-acupuncture is useful in future studies.

Acupuncture↗
PubMed2003

An fMRI study comparing brain activation between word generation and electrical stimulation of language-implicated acupoints.

We compared the brain activation on functional magnetic resonance imaging (MRI) during word generation with the activation during electrical stimulation of two language-implicated acupoints in 17 healthy, Mandarin-speaking, Chinese male volunteers (age 19-26 years). All subjects were strongly right handed according to a handedness inventory. Using a standard functional MRI procedure and a word-generation paradigm, significant activation was seen in the left and right inferior frontal gyri (BA 44, 45) as well as the left superior temporal gyrus (BA 22, 42). Stronger activation with a larger volume was seen in the left hemisphere. Electrical stimulation of either one of the two language-implicated acupoints, SJ 8 (11 subjects) and Du 15 (6 subjects), without the word-generation paradigm in the same cohort, produced significant activation in the right inferior frontal gyrus (BA 44, 46) and in the left and right superior temporal gyri (BA 22, 42), respectively. Nevertheless, no activation was seen in the left inferior frontal gyrus. In addition, electrical stimulation of the adjacent non-acupoints did not produce any significant brain activation. Although our results support the notion of acupoint-brain activation, applying acupuncture at SJ 8 or Du 15 does not activate the typical language areas in the left inferior frontal cortex.

Acupuncture↗
PubMed2003

A prototype methodology combining surface-enhanced laser desorption/ionization protein chip technology and artificial neural network algorithms to predict the chemoresponsiveness of breast cancer cell lines exposed to Paclitaxel and Doxorubicin under in vitro conditions.

An ability to predict the likelihood of cellular response towards particular chemotherapeutic agents based upon protein expression patterns could facilitate the identification of biological molecules with previously undefined roles in the process of chemoresistance/chemosensitivity, and if robust enough these patterns might also be exploited towards the development of novel predictive assays. To ascertain whether proteomic based molecular profiling in conjunction with artificial neural network (ANN) algorithms could be applied towards the specific recognition of phenotypic patterns between either control or drug treated and chemosensitive or chemoresistant cellular populations, a combined approach involving MALDI-TOF matrix-assisted laser desorption/ionization-time of flight mass spectrometry, Ciphergen protein chip technology and ANN algorithms have been applied to specifically identify proteomic 'fingerprints' indicative of treatment regimen for chemosensitive (MCF-7, T47D) and chemoresistant (MCF-7/ADR) breast cancer cell lines following exposure to Doxorubicin or Paclitaxel. The results indicate that proteomic patterns can be identified by ANN algorithms to correctly assign 'class' for treatment regimen (e.g. control/drug treated or chemosensitive/chemoresistant) with a high degree of accuracy using boot-strap statistical validation techniques and that biomarker ion patterns indicative of response/non-response phenotypes are associated with MCF-7 and MCF-7/ADR cells exposed to Doxorubicin. We have also examined the predictive capability of this approach towards MCF-7 and T47D cells to ascertain whether prediction could be made based upon treatment regimen irrespective of cell lineage. Models were identified that could correctly assign class (control or Paclitaxel treatment) for 35/38 samples of an independent dataset. A similar level of predictive capability was also found (> 92%; n = 28) when proteomic patterns derived from the drug resistant cell line MCF-7/ADR were compared against those derived from MCF-7 and T47D as a model system of drug resistant and drug sensitive phenotypes. This approach might offer a potential methodology for predicting the biological behaviour of cancer cells towards particular chemotherapeutics and through protein isolation and sequence identification could result in the identification of biological molecules associated with chemosensitive/chemoresistance tumour phenotypes.

Algorithms↗
PubMed2002

Characterisation of tumour-associated antigens in colon cancer.

In order to search for clinically relevant cancer-associated genes and to define further the spectrum of immunogenic proteins, we applied SEREX (serological identification of antigens by recombinant expression cloning) to analyse genes expressed in colon adenocarcinoma. Eight different serum-reactive cDNA clones were isolated by immunoscreening from a colon cancer-derived cDNA expression library. mRNA expression studies showed that 2 of them, RHAMM and AD034, have a differential tissue distribution, and that 3 genes, NAP1L1, RHAMM and AD034, are overexpressed in tumours in comparison with the adjacent non-cancerous tissues. 5' RLM-RACE analysis of AD034, a sequence with a tyrosine kinase motif, revealed a frameshifting insertion of 32 bp, most likely generated by use of cryptic splice site in tumour-derived cDNA. Analysis of full-length RHAMM cDNA sequence revealed the presence of two splice variants, which are known to have a different sub-cellular localisation; expression of these splice variants is altered in colon cancer tissues. Serological responses to three antigens (C21ORF2, EPRS and NAP1L1) were found mainly in cancer patients' sera.

Adenocarcinoma↗
PubMed2002

Optimised SEREX technique for the identification of leukaemia-associated antigens.

The serological analysis of antigens by recombinant expression cloning (SEREX) has been used by many laboratories to immunoscreen lambda phage cDNA libraries produced from a range of tumour cell types. We and others have found it difficult to extract an optimal quality and quantity of mRNA for the preparation of cDNA libraries which represent the genes transcribed in haematological samples. The difficulty is believed to be due to residual haem groups in the isolated RNA sample which inhibit the activity of reverse transcriptase used in the later production of cDNA. During our preparation of a cDNA library for SEREX studies, we optimised the isolation of mRNA from samples from patients with haematological malignancies. We compared the efficacy of different methods of mRNA extraction using a range of haematological sample sizes and describe the most efficient techniques to maximise mRNA yield and quality for cDNA library production. The phage library we prepared contained a range of cDNA insert sizes, including high molecular weight sequences which, following immunoscreening with autologous patient sera, led to the isolation of 17 novel antigens. Using the methodology described, we have shown SEREX to be effective for the isolation of leukaemia-associated antigens, which may act as targets for immunotherapy.

Aged↗
PubMed2002

Tumor regression induced by intratumor therapy with a disabled infectious single cycle (DISC) herpes simplex virus (HSV) vector, DISC/HSV/murine granulocyte-macrophage colony-stimulating factor, correlates with antigen-specific adaptive immunity.

Direct intratumor injection of a disabled infectious single cycle HSV-2 virus encoding the murine GM-CSF gene (DISC/mGM-CSF) into established murine colon carcinoma CT26 tumors induced a significant delay in tumor growth and complete tumor regression in up to 70% of animals. Pre-existing immunity to HSV did not reduce the therapeutic efficacy of DISC/mGM-CSF, and, when administered in combination with syngeneic dendritic cells, further decreased tumor growth and increased the incidence of complete tumor regression. Direct intratumor injection of DISC/mGM-CSF also inhibited the growth of CT26 tumor cells implanted on the contralateral flank or seeded into the lungs following i.v. injection of tumor cells (experimental lung metastasis). Proliferation of splenocytes in response to Con A was impaired in progressor and tumor-bearer, but not regressor, mice. A potent tumor-specific CTL response was generated from splenocytes of all mice with regressing, but not progressing tumors following in vitro peptide stimulation; this response was specific for the gp70 AH-1 peptide SPSYVYHQF and correlated with IFN-gamma, but not IL-4 cytokine production. Depletion of CD8(+) T cells from regressor splenocytes before in vitro stimulation with the relevant peptide abolished their cytolytic activity, while depletion of CD4(+) T cells only partially inhibited CTL generation. Tumor regression induced by DISC/mGM-CSF virus immunotherapy provides a unique model for evaluating the immune mechanism(s) involved in tumor rejection, upon which tumor immunotherapy regimes may be based.

Animals↗
PubMed2002

Altered splicing pattern of TACC1 mRNA in gastric cancer.

Transforming acidic coiled-coil (TACC) proteins are centrosome and microtubule-associated proteins that are essential for mitotic spindle function. We identified TACC1 as an immunogenic protein and a potential tumor antigen by applying serological identification of antigens by recombinant expression cloning (SEREX) technique to screen a gastric cancer cDNA library. The 5'RLM-RACE and reverse transcriptase polymerase chain reaction analyses revealed at least six different transcript variants of TACC1 with variable transcription start sites and alternative exon usage (designated TACC1-A-TACC1-F). All transcripts differ in their 5' ends but share an identical 3' region encoding coiled-coil domain. Four transcripts were universally expressed in all normal tissues analyzed but TACC1-D and TACC1-F showed a restricted expression pattern. TACC1-F, a transcript representing the SEREX-identified cDNA clone, was predominantly expressed in brain and gastric tumors to a similar level. TACC1-D was only weakly detectable in kidney and colon but not in other normal tissues, while a relatively strong expression was observed in 50% of gastric cancer tissue samples analyzed. These transcript variants are generated possibly as a result of alterations in efficiency and pattern of alternative splicing; these isoforms may represent genetic markers, for example TACC1-D for gastric cancer. We also propose that inappropriate expression of the isoforms in gastric cancer cells might result in dysfunction of TACC1 thus contributing to the genetic instability.

Alternative Splicing↗
PubMed2002

Disabled infectious single cycle-herpes simplex virus (DISC-HSV) as a vector for immunogene therapy of cancer.

Disabled infectious single cycle-herpes simplex viruses (DISC-HSV) have been shown to be safe for use in humans and may be considered efficacious as vectors for immunogene therapy in cancer. Preclinical studies show that DISC-HSV is an efficient delivery system for cytokine genes and antigens. DISC-HSV infects a high proportion of cells, resulting in rapid gene expression for at least 72 h. The DISC-HSV-mGM-CSF vector, when inoculated into tumors, induces tumor regression in a high percentage of animals, concomitant with establishing a cytotoxic T-cell response, which is MHC class I restricted and directed against peptides of known tumor antigens. The inherent properties of DISC-HSV makes it a suitable vector for consideration in human immunogene therapy trials.

Animals↗