The vault project : down-regulation of vault RNA expression via iRNA technology leads to increased drug sensitivity in small cell lung cancer : [an honors thesis (HONRS 499)]

Thumbnail Image
Moore, Katina N.
Vann, Carolyn N.
Issue Date
Thesis (B.?.)
Honors College
Other Identifiers

Small-cell lung cancer cells, GLC4, that confer a multi-drug resistance (MDR) phenotype are resistant to the chemotherapeutic drug doxorubicin. Concurrent with MDR is an upregulation of cytoplasmic vaults, ribonucleoprotein particles that have a proposed function in nuclear-cytoplasmic transport. GLC4 cells were subjected to interfering RNA (iRNA) treatment that down-regulated expression of one of the RNA species (vRNA1) associated with the vault complex. These cells, termed psi-VRNAI, along with appropriate control cells were treated with low (345 nM) and high (1035 nM) concentrations of doxorubicin for 6 hrs, 12 hrs, and 24 hrs and assessed for apoptotic activity.Preliminary data suggest that destabilization of the vault structure reestablishes GLC4 sensitivity to doxorubicin. A caspase-8 colorimetric assay (Sigma) was utilized to gauge apoptotic activity. At the 6-hour time point a slight increase in apoptosis was observed in the psi-VRNA1 cells, which no longer expressed functional vaults, when compared to GLC4 normal controls. Most interestingly, at 12-hours a maximal apoptotic response was seen at the lower concentration of doxorubicin. After 24-hours of treatment with doxorubicin the same response is not observed. In this preliminary investigation, the data suggests that a 12-hour, 345 nM exposure of doxorubicin provides the optimal treatment regime to induce maximal levels of apoptosis.