Lomustine, methotrexate and cytarabine chemotherapy as a rescue treatment for feline lymphoma

Production of pyrimidine nucleosides in microbial systems via metabolic engineering: Theoretical analysis research and prospects

Pyrimidine nucleosides, as intermediate materials of significant commercial value, find extensive applications in the pharmaceutical industry. However, the current production of pyrimidine nucleosides largely relies on chemical synthesis, creating environmental problems that do not align with sustainable development goals. Recent progress in systemic metabolic engineering and synthetic biology has enabled the synthesis of natural products like pyrimidine nucleosides through microbial fermentation, offering a more sustainable alternative. Nevertheless, the intricate and tightly regulated biosynthetic pathways involved in the microbial production of pyrimidine nucleosides pose a formidable challenge. This study focuses on metabolic engineering and synthetic biology strategies aimed at enhancing pyrimidine nucleoside production. These strategies include gene modification, transcriptional regulation, metabolic flux analysis, cofactor balance optimization, and transporter engineering. Finally, this research highlights the challenges involved in the further development of pyrimidine nucleoside-producing strains and offers potential solutions in order to provide theoretical guidance for future research endeavors in this field.

Improving the level of the cytidine biosynthesis in E. coli through atmospheric room temperature plasma mutagenesis and metabolic engineering

AIMS

Cytidine, as an important commercial precursor in the chemical synthesis of antiviral and antitumor drugs, is in great demand in the market. Therefore, the purpose of this study is to build a microbial cell factory with high cytidine production.

METHODS AND RESULTS

A mutant E. coli NXBG-11-F34 with high tolerance to uridine monophosphate structural analogs and good genetic stability was obtained by atmospheric room temperature plasma (ARTP) mutagenesis combined with high-throughput screening. Then, the udk and rihA genes involved in cytidine catabolism were knocked out by CRISPR/Cas9 gene editing technology, and the recombinant strain E. coli NXBG-13 was constructed. The titer, yield, and productivity of cytidine fermented in a 5 l bioreactor were 15.7 g l-1, 0.164 g g-1, and 0.327 g l-1 h-1, respectively. Transcriptome analysis of the original strain and the recombinant strain E. coli NXBG-13 showed that the gene expression profiles of the two strains changed significantly, and the cytidine de novo pathway gene of the recombinant strain was up-regulated significantly.

CONCLUSIONS

ARTP mutagenesis combined with metabolic engineering is an effective method to construct cytidine-producing strains.

Novel Treatments for Lymphoma

Lymphoma is a common disease in companion animals. While conventional chemotherapy has the potential to induce remission and prolong life, relapse is common and novel treatments are needed to improve outcome. This review discusses recent modifications/adjustments to conventional standard of care therapy for canine and feline lymphoma, options for treatment or relapsed/refractory disease, and cutting-edge immunotherapy and small molecule-based approaches that are in varying stages of regulatory approval.

Artesunate reverses cytarabine resistance in acute myeloid leukemia by blocking the JAK/STAT3 signaling

OBJECTIVES

Although cytarabine (AraC) has greatly contributed to improving the prognosis of patients with acute myeloid leukemia (AML), many patients developed drug resistance and eventually succumbed to AML. Thus, resistance to AraC is a major obstacle to improve the efficacy of chemotherapy in AML. Hence, this study aimed to demonstrate that artesunate (ART) can reliably induce cell death in vitro and block AraC resistance.

METHODS

AML cell lines resistant to AraC were first constructed by repeated dosing for 5 months. Further, we analyzed whether ART intervention affected the sensitivity of AraC-resistant cells to AraC by cell function experiments, mainly including CCK-8 to assess cell viability, flow cytometry to examine apoptosis, and Western blotting to measure the Janus kinase (JAK)/signal transducers and activators of transcription 3 (STAT3) pathway protein expression. Furthermore, whether JAK/STAT3 pathway knockdown has a blocking effect on the efficacy of ART was also assessed.

RESULTS

Co-treatment of ART and AraC increased the sensitivity of AML cells to AraC. Also, it effectively reversed the resistance of AML cells to AraC that is shown by the significantly reduced proliferation and increased apoptosis rates. ART intervention suppressed the activation of the JAK/STAT3 signaling pathway in AraC-resistant AML cells, suggesting that the function of ART in reversing AraC resistance is indeed dependent on the JAK/STAT3 signaling pathway.

CONCLUSIONS

In summary, ART enhanced the sensitivity of AML/AraC-resistant cells to AraC by modulating the JAK/STAT3 pathway.

Successful rescue treatment using chlorambucil for presumed recurrence of sinonasal lymphoma in a cat

Case summary

A 12-year-old male neutered domestic shorthair cat presented with a 2-week history of serous unilateral nasal discharge, swelling of the nasal bridge and sneezing. Whole-body CT revealed a mass filling the entire right nasal cavity with lysis of the cribriform plate. The cat was diagnosed with sinonasal large-cell lymphoma based on cytopathological analysis, with PCR-based lymphocyte clonality testing showing a monoclonal population with rearrangement of the immunoglobulin heavy chain gene. The cat received radiotherapy with a dose of 30 Gy in seven fractions given three times weekly, and then cyclophosphamide, doxorubicin, vincristine and prednisolone (CHOP)-based chemotherapy was initiated soon after completion of the radiotherapy schedule. Despite this treatment, CT performed 4 months after radiotherapy revealed enlargement of the lesion in the right nasal cavity consistent with presumed progression of the cat’s lymphoma. The cat then received rescue chemotherapy with chlorambucil, which markedly reduced the size of the disease burden in the nasal and frontal sinus without severe adverse effects. At the time of writing, the cat was receiving chlorambucil for 7 months without any clinical signs suggestive of tumour relapse.

Relevance and novel information

To our knowledge, this is the first case of feline sinonasal lymphoma with chlorambucil used as rescue chemotherapy. This case indicates that chemotherapy with chlorambucil may be a useful treatment option for cats with relapsing sinonasal lymphoma following radiotherapy and/or CHOP-based chemotherapy.