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In our translational research, an immunotherapeutic, ADCTA-G, has been developed to emphasize autologous tumor antigens, DC antigen processing/presentation, enhanced tumor immunogenicity and CTL induction. Two clinical trials, Phase I/II [2003-2005Taiwan DOH/MA 0910072504] and phase II [2005–2016 NIH {"type":"clinical-trial","attrs":{"text":"NCT02772094","term_id":"NCT02772094"}}NCT02772094], “Dendritic Cell(DC)-Based Tumor Vaccine Adjuvant Immunotherapy of Human Glioblastoma Multiforme”, respectively enrolled 17 and 42 WHO Grade-IV glioblastomas. Every patient received peripheral blood apheresis for PBMNCs. Monocytes were used for derivation of 3-7x108 phagocytic dendritic cells (iDC). Autologous glioma cells grown out of surgical tumor specimen were irradiated and co-cultivated 1 to 2:1 with iDC to make a ADCTA-G lot. After surgical tumor de-bulking, 10 vaccinations were given, each with 2-5x107 mature DC from the ADCTA lot, in a [4x biweekly and 6x monthly] scheduled s.c. injection in both axillar regions. The follow-up period has been 15 years. Primary endpoint is the overall survival (OS); phenotypes of tumor infiltrating T cells and tumor IDH mutation were also analyzed for long-term survivors. The ADCTA-G inoculations were tolerated well, and curtailed the grade-3/4 lymphopenia adverse effect of the temozolomide CCRT. The median OS is 22.9 months for the total 59 grade IV patients in the two trials. The median OS is 21.8 months for the 44 newly diagnosed patients and 28.1 months for the 15 recurrent patients; the difference is insignificant statistically. In this study, vaccinations were initiated early in the recurrent GBM patients while the newly diagnosed GBM patients had to wait till after external radiation therapy, leading to a comparable OS benefit of the ADCTA vaccination. Also, we demonstrated in vitro the earlier vaccinations in the recurrent decrease CD133+ tumor stem-like cells. In addition, the CD8(+) cells were susceptible to ionizing radiation. A phase 3 open-labelled randomized study will be initiated to improve the survival of this aggressive malignancy.

Glioblastoma multiforme (GBM) is the most prevalent and high malignant primary brain tumors, and contains a small cohort of self-renewing, tumorigenic glioblastoma stem cells (GSCs) that contribute to tumor relapse and therapeutic resistance. GSCs are typically recognized by the expression of cell surface marker, CD133, encoded from prominin-1 (PROM1) gene. Recent studies have indicated CD133+ cancer stem-like cells are enriched after the treatment of ionizing radiation (IR). To investigate the effect of cytotoxic TILs to glioblastoma cells experienced irradiation, we used post-vaccination TILs treat with glioblastoma cells derived from patient’s tissue specimens without experienced and experienced irradiation respectively. The effect of cytotoxic TILs was not evident in glioblastoma cells experienced IR until 120 hours later. To further investigate whether immune cytokines have cytotoxicity in CD133+ glioblastoma cells, we observed that TNF-α and IFN-γ have the cytotoxic effects in CD133+ glioblastoma cells, implicating the reason why the cytotoxic of CD8+ TILs were delayed to 120 hours. These data provide the framework for understanding the radioresistance in glioblastoma cells that can be used to develop an efficient vaccine.

The first microRNA, let-7, and its family were discovered in Caenorhabditis elegans and are functionally conserved from worms to humans in the regulation of embryonic development and stemness. The let-7 family has been shown to have an essential role in stem cell differentiation and tumor-suppressive activity. Deregulating expression of let-7 is commonly reported in many human cancers. Emerging evidence has accumulated and suggests that reestablishment of let-7 in tumor cells is a valuable therapeutic strategy. However, findings reach beyond tumor therapeutics and may impinge on stemness and differentiation of stem cells. In this review, we discuss the role of let-7 in development and differentiation of normal adult stem/progenitor cells and offer a viewpoint of the association between deregulated let-7 expression and tumorigenesis. The regulation of let-7 expression, cancer-relevant let-7 targets, and the application of let-7 are highlighted.

Alternative splicing involves differential exon selection of a gene transcript to generate mRNA and protein isoforms with structural and functional diversity. Abnormal alternative splicing has been shown to be associated with malignant phenotypes of cancer cells, such as chemo-resistance and invasive activity. Screening small molecules and drugs for modulating RNA splicing in human hepatocellular carcinoma cell line Huh-7, we discovered that amiloride, distinct from four pH-affecting amiloride analogues, could “normalize” the splicing of BCL-X, HIPK3 and RON/MISTR1 transcripts. Our proteomic analyses of amiloride-treated cells detected hypo-phosphorylation of splicing factor SF2/ASF, and decreased levels of SRp20 and two un-identified SR proteins. We further observed decreased phosphorylation of AKT, ERK1/2 and PP1, and increased phosphorylation of p38 and JNK, suggesting that amiloride treatment down-regulates kinases and up-regulates phosphatases in the signal pathways known to affect splicing factor protein phosphorylation. These amiloride effects of “normalized” oncogenic RNA splicing and splicing factor hypo-phosphorylation were both abrogated by pre-treatment with a PP1 inhibitor. Global exon array of amiloride-treated Huh-7 cells detected splicing pattern changes involving 584 exons in 551 gene transcripts, many of which encode proteins playing key roles in ion transport, cellular matrix formation, cytoskeleton remodeling, and genome maintenance. Cellular functional analyses revealed subsequent invasion and migration defects, cell cycle disruption, cytokinesis impairment, and lethal DNA degradation in amiloride-treated Huh-7 cells. Other human solid tumor and leukemic cells, but not a few normal cells, showed similar amiloride-altered RNA splicing with devitalized consequence. This study thus provides mechanistic underpinnings for exploiting small molecule modulation of RNA splicing for cancer therapeutics.

Malignant gliomas, particularly glioblastoma multiforme (GBM) tumors, are very difficult to treat by conventional approaches. Although most of the tumor mass can be removed by surgical resection, radiotherapy, and chemotherapy, it eventually recurs. There is growing evidence that cancer stem cells (CSCs) play an important role in tumor recurrence. These stem cells are radioresistant and chemoresistant. The most commonly used tumor marker for CSCs is CD133. The amount of CSC component is closely correlated with tumor malignancy grading. Isolating, identifying, and treating CSCs as the target is crucial for treating malignant gliomas. CSC-associated vascular endothelial growth factor (VEGF) promotes tumor angiogenesis, tumor hemorrhage, and tumor infiltration. Micro-RNA (miRNA) plays a role in CSC gene expression, which may regulate oncogenesis or suppression to influence tumor development or progression. The antigenesis of CSCs and normal stem cells may be different. The CSCs may escape the T-cell immune response. Identifying a new specific antigen from CSCs for vaccine treatment is a key point for immunotherapy. On the other hand, augmented treatment with radiosensitizer or chemosensitizer may lead to reduction of CSCs and lead to CSCs being vulnerable to radiotherapy and chemotherapy. The control of signaling pathway and cell differentiation to CSC growth is another new hope for treatment of malignant gliomas. Although the many physiological behavioral differences between CSCs and normal stem cells are unclear, the more we know about these differences the better we will be able to treat CSCs effectively.

Soluble extracts of mouse cells with Fv-1 n or Fv-1 b gene alleles specifically and reciprocally inhibit infection of B- or N-tropic mouse leukemia viruses in permissive cell cultures. NB-tropic virus infection was not inhibited by either cell extract. Extracts from Fv-1 - cells did not inhibit infection by the three virus host-range types, but N- or B-tropic virus infection of Fv-1 - cells was inhibited by extracts of the nonpermissive cells, and Fv-1 nb cell extracts inhibited both viruses. The maximum degree of inhibition was 50-80% as determined by immunofluorescent or plaque assays, with extracts containing up to 500 μg/ml of nonpermissive cell protein. The inhibitor(s) is relatively unstable since activity is lost after 2 hr at 37° or 30 min at 56°. The inhibitor(s) was most effective if added 2 hr before or within 2 hr after infection, did not react with the virus directly, inhibit virus attachment, or inhibit the normal cell functions tested. These results indicate that nonpermissive mouse cells contain a product, possibly determined by the Fv-1 gene, which inhibits some early postpenetration event(s) in leukemia virus infection.

A standardized bioassay for transfer of Fv-1 gene-specific resistance to N-tropic and B-tropic murine retroviruses was developed using X plaque reduction in SC-1 (Fv-1-) cells inoculated with virus. Testing of subcellular fractions of restrictive cells showed that the resistance transfer activity was present in the cytoplasmic (microsomal and cytosol) fractions. The activity of the cytoplasmic extract was destroyed by treatment with ribonuclease, but not with deoxyribonuclease or proteases. RNA prepared by phenol-chloroform extraction of mouse tissues, including embryos and livers of weanling mice, transferred Fv-1 locus-specific resistance into DEAE-dextran-treated SC-1 cells. The activity of isolated RNA preparations against virus of the appropriate host-range type has been demonstrated to correspond to the Fv-1 genotypes of the cell sources. The specific transfer of resistance with cellular RNA was effective within a 5- to 6-h period from 2 h before to 4 to 5 after virus infection. Sucrose gradient centrifugation of the RNA showed that the activity sedimented as a broad peak, with an apparent maximum in the 22S region. Affinity chromatography of whole-cell RNA on polyuridylic acid-Sepharose tended to separate more activity into the polyadenylic acid RNA fraction than the non-polyadenylic acid RNA fraction. Except for the reciprocal inhibitory activity for the two host-range virus types, the RNAs of Fv-1n and Fv-1b specificities showed similar properties in all aspects studied.

Previously, in vitro recombinant DNA studies demonstrated that genetic determinants of N-tropism and B-tropism, or Fv-1-related host range properties of murine leukemia viruses, were located in a BamHI-HindIII DNA segment derived from the 5' portion of the cloned viral genome. We sequenced this segment and its immediate 5' region from cloned DNA of two BALB/c mouse C-type viruses (WN1802N and WN1802B) and found base differences at 12 positions out of the otherwise identical 1,390-base-pair sequences. Analysis of the most likely reading frame showed that 6 of the 12 base differences would result in four encoded amino acid changes, three of which occur at positions 109 (glutamine in WN1802N versus threonine in WN1802B), 110 (arginine in WN1802N versus glutamic acid in WN1802B), and 159 (glutamic acid in WN1802N versus glycine in WN1802B) of the p30 protein. The remaining one is located at position 36 (threonine in WN1802N versus isoleucine in WN1802B) of the viral polymerase protein. Significant conformational alteration of the p30 protein could be predicted from these amino acid changes.