Asuka Setoguchi

Monitoring of Minimal Residual Disease (MRD) after Multidrug Chemotherapy and Its Correlation to Outcome in Dogs with Lymphoma: A Proof-of-Concept Pilot Study

BACKGROUNDnTumor cell burden in dogs with lymphoma cannot be assessed accurately by diagnostic evaluation during clinical complete remission (CR). Recent advances in polymerase chain reaction (PCR)-based methods enabled us to quantify minimal residual disease (MRD) in canine lymphoma.nnnHYPOTHESIS/OBJECTIVESnTo quantify MRD in dogs with lymphoma treated with multidrug chemotherapy and to correlate it with remission duration after chemotherapy.nnnANIMALSnSeventeen dogs with lymphoma that achieved CR by multidrug chemotherapy.nnnMETHODSnRearranged immunoglobulin heavy chain or T-cell receptor gamma chain gene fragments from lymphoma cells were PCR amplified and sequenced to prepare clone-specific primers and probes for real-time PCR to quantify MRD. MRD in the peripheral blood was monitored during and at the end of a 25-week multidrug chemotherapy protocol. Correlation between MRD at the end of chemotherapy and remission duration after chemotherapy was analyzed.nnnRESULTSnMRD gradually decreased after initiation of multidrug chemotherapy, reached a nadir as low as <0.019-1.0 cells/microL at weeks 4-17, and remained low or slightly increased until week 25. MRD at the end of chemotherapy was negatively correlated with remission duration from the end of chemotherapy to relapse.nnnCONCLUSION AND CLINICAL IMPORTANCEnMRD could be an objective marker to indicate tumor cell burden in dogs with lymphoma even in clinical CR. MRD at the end of chemotherapy could be a prognostic factor to predict remission duration after chemotherapy.

Antiviral activity of membrane fusion inhibitors that target gp40 of the feline immunodeficiency virus envelope protein

For the entry of lentivirus into target cells, fusion between its viral membrane and cellular membrane is essential. The present study was conducted to examine the inhibitory effect of modified peptides corresponding to heptad repeats (HR) 1 and 2 of feline immunodeficiency virus (FIV) envelope gp40 on the fusion between the viral and cellular membranes. FIV-N36 and FIV-C35 were synthesized as authentic peptides of the N-terminal HR1 domain and C-terminal HR2 domain of FIV gp40, respectively. FIV-C35EK1, FIV-C35EK2, and FIV-C35EK3 were peptides synthesized by modifying FIV-C35 as the X-EE-XX-KK concept to increase their solubility in water and the stability of their alpha-helicity. FIV-C35 and FIV-C35EK1 inhibited the cell membrane fusion mediated by FIV-infected cells and the replication of FIV. FIV-N36, FIV-C35EK2, and FIV-C35EK3 did not show any apparent inhibitory effect. These results indicated that the newly developed membrane fusion inhibitors could facilitate the development of novel anti-lentiviral chemotherapies.

Molecular cloning of feline interferon-γ-inducing factor (interleukin-18) and its expression in various tissues

Interleukin-18 (IL-18) is a cytokine with potent interferon-gamma-inducing activity, and plays an important biologic role in the enhancement of the activity of natural killer cells and cytotoxic T-lymphocytes. In this study, feline IL-18 cDNA was cloned and characterized to establish a basis for the prospective cytokine therapy in small animal practice. The nucleotide sequence of feline IL-18 cDNA obtained in this study was 712bp long and contained its entire open reading frame encoding 192 amino acid residues. The predicted amino acid sequence of feline IL-18 cDNA showed 77.2, 84.8, 60.2 and 62.6% similarity with those of human, dog, rat and mouse counterparts, respectively. The feline IL-18 cDNA included a putative cleavage site of IL-1beta-converting enzyme (ICE) and IL-1 signature-like sequences identified in human and mouse IL-18 cDNAs. Expression of IL-18 mRNA was detected in various tissues including spleen, liver and cerebrum in the cat.

Mutation of p53 Gene and Its Correlation with the Clinical Outcome in Dogs with Lymphoma

Background p53 plays a key role in the apoptotic event induced by chemotherapeutic agents. Mutation of p53 gene has been observed in various spontaneous tumors in humans and is associated with a poor prognosis. p53 abnormalities have been evaluated in several tumors in dogs; however, the association of p53 gene mutation with clinical outcome in dogs with lymphoma has not been documented. Hypothesis/Objectives The aim of this study was to examine p53 mutation in canine lymphoma cells and its association with the clinical outcome. Animals Forty‐three dogs with previously untreated high‐grade lymphoma referred to the University of Tokyo were included in this study. Methods Prospective cohort study. We examined p53 gene (exon 4–8) mutation in the tumor tissues from 43 dogs with lymphoma using PCR‐SSCP (polymerase chain reaction – single‐strand conformational polymorphism) analysis, followed by nucleotide sequencing of the abnormal bands. Results Of the 43 dogs, 7 dogs (16%) had p53 mutation, whereas 36 dogs (84%) were devoid of p53 mutation. Overall response rate after remission induction was significantly lower (33% versus 88%, P = .002) in dogs with lymphomas having p53 mutation than those with lymphomas devoid of p53 mutation. Overall survival time was significantly shorter (67 days versus 264 days, P = .004) in dogs with lymphoma with p53 mutation than those with lymphoma retaining wild‐type p53. Conclusion and Clinical Importance Mutations of p53 gene were detected in a proportion of canine lymphoma cells from untreated dogs and can be associated with a poor prognosis.

Cloning and Chromosome Mapping of the Feline Genes p21WAF1 and p27Kip1

For investigation of the relation of cell cycle regulation with tumorigenesis in cats, we carried out molecular cloning of feline p21WAF1 and p27Kip1 cDNAs and chromosomal mapping of these genes on the cat genome. The feline p21WAF1 cDNA clone obtained in this study encoded 164 amino acids (aa) showing 83.5% and 76.8% sequence similarity with those of the human and mouse counterparts, respectively. The cat p27Kip1 cDNA clone isolated here encoded 198 aa, showing sequence similarities of 93.4% and 90.4% with its human and mouse counterparts, respectively. Using a panel of feline x rodent somatic cell hybrids, the feline CDKN1A (p21WAF1) and CDKN1B (p27Kip1) loci were assigned to feline chromosomes B2 and B4, respectively. Southern-blot analyses of 17 feline spontaneous leukemia and lymphoma cases using these cDNAs as probes did not reveal any rearrangements in either the p21WAF1 or the p27Kip1 gene. RT-PCR/SSCP (single strand conformation polymorphism) analysis of p27Kip1 cDNA did not uncover any amino acid substitutions in the 10 feline leukemia and lymphoma cases that were examined.