Usp37 inactivation as a treatment for plzf/rara-associated acute promyelocytic leukemia

A method of assaying and/or identifying a test agent as a regulator of the stability and/or the intracellular level of the fusion protein PLZF/RARA, comprising:

• (a) providing a cell comprising:
• (i) a first reporter protein operably linked to a tetracycline response element and the PLZF/RARA;
• and (ii) a second reporter protein operably linked to an internal ribosome entry site (IRES) and the PLZF/RARA, and treating the cell with the test agent or a vehicle control;
• (b) inducing the cell to express the reporter proteins and measuring the intensity of the first reporter protein and the intensity of the second reporter protein, and calculating the ratio of the intensity of the first reporter protein versus the intensity of the second reporter protein in the presence and the absence of the test agent;
• and
• (c) identifying the test agent as a regulator of the stability and/or the level of the fusion protein PLZF/RARA when the ratio in the presence of the test agent is less than that in the vehicle control;
• or
• (i) providing a cell constitutively expressing a transduced fusion protein PLZF/RARA and a transduced USP37, and treating the cell with the test agent or a vehicle control;
• (ii) measuring the amount of the PLZF/RARA in the presence and the absence of the test agent;
• and
• (iii) identifying the test agent as a regulator of the stability and/or the level of the fusion protein PLZF/RARA when the amount of the PLZF/RARA in the presence of the test agent is less than that in the vehicle control;
• or
• (1) providing a cell constitutively expressing a transduced fusion protein PLZF/RARA and a transduced USP37, and treating the cell with a proteasome inhibitor, which reduces the degradation of ubiquitin-conjugated proteins, and the test agent or a vehicle control;
• (2) measuring the amount of ubiquitin-conjugated PLZF/RARA within the cell in the presence and the absence of the test agent;
• and
• (3) identifying the test agent as a regulator of the stability and/or the level of the fusion protein PLZF/RARA when the amount of the ubiquitin-conjugated PLZF/RARA in the presence of the test agent is more than that in the vehicle control.