Nucleic acid construct set, kit, detection method and method for predicting drug effect

A kit for detecting a DNA homologous recombination deficiency, the kit comprising:

• lipid particles;
• a first nucleic acid construct encapsulated in the lipid particles, the first nucleic acid construct including a first promoter sequence and a cleaved Cre gene ligated to downstream of the first promoter sequence;
• and a second nucleic acid construct encapsulated in the lipid particles, the second nucleic acid construct including a second promoter sequence, a first loxP sequence ligated to downstream of the second promoter sequence, a reporter gene ligated to downstream of the first loxP sequence, and a second loxP sequence ligated to downstream of the reporter gene, wherein the cleaved Cre gene is composed of two Cre gene fragments obtained by cleaving the Cre gene into two parts without deletion of the base sequence of the Cre gene so as to be inactivated, and of the two Cre gene fragments, an upstream gene fragment of the Cre gene is linked downstream of the first promoter sequence, and a downstream gene fragment of the Cre gene is linked upstream of the first promoter sequence, wherein the 5′ end of the upstream gene fragment of the Cre gene is linked to a second sequence having a base sequence identical to a portion of the 3′ end of the downstream gene fragment of the Cre gene, which is the first sequence, and where in homologous recombination of the first and second sequences results in a functional Cre gene.

A method for detecting cells having a DNA homologous recombination deficiency, the method comprising:

• transfecting, into test cells, a first nucleic acid construct including a first promoter sequence and a cleaved Cre gene ligated to downstream of the first promoter sequence and a second nucleic acid construct including a second promoter sequence, a first loxP sequence ligated to downstream of the second promoter sequence, a reporter gene ligated to downstream of the first loxP sequence, and a second loxP sequence ligated to downstream of the reporter gene, wherein the cleaved Cre gene is composed of two Cre gene fragments obtained by cleaving the Cre gene into two parts without deletion of the base sequence of the Cre gene so as to be inactivated, and of the two Cre gene fragments, an upstream gene fragment of the Cre gene is linked downstream of the first promoter sequence, and a downstream gene fragment of the Cre gene is linked upstream of the first promoter sequence;
• culturing the test cells;
• and detecting an activity of a protein expressed from the reporter gene, wherein the 5′ end of the upstream gene fragment of the Cre gene is linked to a second sequence having a base sequence identical to a portion of the 3′ end of the downstream gene fragment of the Cre gene, which is the first sequence, and wherein homologous recombination of the first and second sequences results in a functional Cre gene.

A method for predicting an effect of a drug, the method comprising:

• transfecting, into test cells derived from a subject, a first nucleic acid construct comprising a first promoter sequence and a cleaved Cre gene ligated to downstream of the first promoter sequence and a second nucleic acid construct comprising a second promoter sequence, a first loxP sequence ligated to downstream of the second promoter sequence, a reporter gene ligated to downstream of the first loxP sequence, and a second loxP sequence ligated to downstream of the reporter gene, wherein the cleaved Cre gene is composed of two Cre gene fragments obtained by cleaving the Cre gene into two parts without deletion of the base sequence of the Cre gene so as to be inactivated, and of the two Cre gene fragments, an upstream gene fragment of the Cre gene is linked downstream of the first promoter sequence, and a downstream gene fragment of the Cre gene is linked upstream of the first promoter sequence;
• culturing the test cells;
• detecting a signal from a protein expressed from the reporter gene;
• calculating a positive rate of cells having a DNA homologous recombination deficiency included in the test cells based on a result of the detecting;
• and predicting an effect of a drug which is effective against a cancer with the DNA homologous recombination deficiency on a cancer in the subject based on the positive rate, wherein the 5′ end of the upstream gene fragment of the Cre gene is linked to a second sequence having a base sequence identical to a portion of the 3′ end of the downstream gene fragment of the Cre gene, which is the first sequence, and wherein homologous recombination of the first and second sequences results in a functional Cre gene.