Patient-derived ovarian cancer organoids capture the genomic profiles of primary tumours applicable for drug sensitivity and resistance testing.

The use of primary patient-derived organoids for drug sensitivity and resistance testing could play an important role in precision cancer medicine. We developed expandable ovarian cancer organoids in < 3 weeks; these organoids captured the characteristics of histological cancer subtypes and replicated the mutational landscape of the primary tumours. Seven pairs of organoids (3 high-grade serous, 1 clear cell, 3 endometrioid) and original tumours shared 59.5% (36.1-73.1%) of the variants identified. Copy number variations were also similar among organoids and primary tumours. The organoid that harboured the BRCA1 pathogenic variant (p.L63*) showed a higher sensitivity to PARP inhibitor, olaparib, as well as to platinum drugs compared to the other organoids, whereas an organoid derived from clear cell ovarian cancer was resistant to conventional drugs for ovarian cancer, namely platinum drugs, paclitaxel, and olaparib. The overall success rate of primary organoid culture, including those of various histological subtypes, was 80% (28/35). Our data show that patient-derived organoids are suitable physiological ex vivo cancer models that can be used to screen effective personalised ovarian cancer drugs.

Genome-wide identification of the targets for genetic manipulation to improve L-lactate production by Saccharomyces cerevisiae by using a single-gene deletion strain collection.

To identify genome-wide targets for gene manipulation for increasing L-lactate production in recombinant Saccharomyces cerevisiae strains, we transformed all available single-gene deletion strains of S. cerevisiae with a plasmid carrying the human L-lactate dehydrogenase gene, and examined L-lactate production in the obtained transformants. The thresholds of increased or decreased L-lactate production were determined based on L-lactate production by the standard strain in repetitive experiments. L-lactate production data for 4802 deletion strains were obtained, and deletion strains with increased or decreased L-lactate production were identified. Functional category analysis of genes whose deletion increased L-lactate production revealed that ribosome biogenesis-related genes were overrepresented. Most deletion strains for genes related to ribosome biogenesis exhibited increased L-lactate production in 200-ml batch cultures. We deleted the genes related to ribosome biogenesis in a recombinant strain of S. cerevisiae with a genetic background different from that of the above deletion strains, and examined the effect of target gene deletion on L-lactate production. We observed that deletion of genes related to ribosome biogenesis leads to increased L-lactate production by recombinant S. cerevisiae strains, and the single-gene deletion strain collection could be utilized in identifying target genes for improving L-lactate production in S. cerevisiae recombinant strains.

Investigating the effectiveness of DNA microarray analysis for identifying the genes involved in l-lactate production by Saccharomyces cerevisiae.

In order to determine whether transcriptome data obtained by DNA microarray analysis could be used to identify the genes involved in target metabolite production, we tried to identify the genes involved in L-lactate production by L-lactate-producing recombinant Saccharomyces cerevisiae strains. We obtained DNA microarray data for these strains. Plasmids carrying lactic acid bacteria, bovine, and human L-lactate dehydrogenase (LDH) genes were introduced into PDC1-disrupted S. cerevisiae strains. L-Lactate productivity of the strains harboring the human and bovine LDH genes was higher than that of the strains harboring lactic acid bacteria LDH genes. DNA microarray analysis revealed that the expression of 388 genes was significantly altered in the strains with the human and bovine LDH genes. Of these, the L-lactate productivity of human LDH-harboring deletion strains of 289 genes was compared with that of the standard and 56 randomly selected deletion strains containing the same LDH gene to validate the effectiveness of DNA microarray analysis for identifying the genes responsible for L-lactate production in the recombinant strains. Only deletion strains of the genes selected on the basis of the DNA microarray data showed significantly altered L-lactate production as compared to the standard and the randomly selected deletion strains. Our results indicated that the genes related to L-lactate production could be successfully identified by selecting the genes that exhibited significantly altered expression on DNA microarray analysis, and the effectiveness of DNA microarray analysis for identifying the genes responsible for L-lactate production was discussed.

Improvement of L-lactate production by CYB2 gene disruption in a recombinant Saccharomyces cerevisiae strain under low pH condition.

Using a DNA microarray, we found that expression of the genes related to lactate metabolism was upregulated in a lactate-producing recombinant Saccharomyces cerevisiae strain. Disruption of the CYB2 gene encoding L-lactate dehydrogenase improved the L-lactate production by S. cerevisiae under low pH condition.