In a previous report, we identified the receptor for activated C-kinase 1 (RACK1) as a positive regulator of the cellular localization and expression of ATP-binding cassette B4, a phosphatidylcholine translocator expressed on the bile canalicular membrane. In the present study, we focused on the role of RACK1 on ATP-binding cassette G2 (ABCG2), which is responsible for the cellular extrusion of...

Overexpression of multidrug resistance protein ABCG2 has been associated to chemotherapy failure in solid and hematologic tumors. More than 40 ‘synonymous’ and ‘non-synonymous’ single nucleotide polymorphisms (SNPs) of ABCG2 have been identified. Among them, the 421C>A (Q141K), that is also the most common in Caucasian ethnicity (around 10%) has been shown to alter protein function and to modif...

Overexpression of ABCG2 is considered a major mechanism of cancer drug resistance. Recent studies have shown that ABCG2 can regulate the switch between symmetric and asymmetric cell division in adult stem cells; however, the relationship between ABCG2 and cell division in drug-resistant cancer cells remains to be determined. In the present study, we demonstrated that ABCG2 is involved in the ce...

Purine nucleoside antimetabolites, such as clofarabine, are effective antileukemic agents. However, their effectiveness depends on an initial activation step in which they are monophosphorylated by deoxycytidine kinase (dCK). Some purine nucleoside antimetabolites and their monophosphate derivatives are exported by the ABC transporter ABCG2. Because clofarabine is a dCK substrate, and we show s...

ABCG2 is a transporter with potential importance in cancer drug resistance, drug oral absorption, and stem cell biology. In an effort to identify novel inhibitors of ABCG2, we examined the ability of commercially available bisindolylmaleimides (BIM) and indolocarbazole protein kinase inhibitors (PKI) to inhibit ABCG2, given the previous demonstration that the indolocarbazole PKI UCN-01 interact...

Side population (SP) and ABC transporter expression enrich for stem cells in numerous tissues. We explored if this phenotype characterised human bladder cancer stem cells (CSCs) and attempted to identify regulatory mechanisms. Focusing on non-muscle invasive bladder cancer (NMIBC), multiple human cell lines were used to characterise SP and ABC transporter expression. In vitro and in vivo phenot...

We sought to characterize the interactions of flavopiridol with members of the ATP-binding cassette (ABC) transporter family. Cells overexpressing multidrug resistance-1 (MDR-1) and multidrug resistance-associated protein (MRP) did not exhibit appreciable flavopiridol resistance, whereas cell lines overexpressing the ABC half-transporter, ABCG2 (MXR/BCRP/ABCP1), were found to be resistant to fl...

BACKGROUND The BCRP/ABCG2 transporter, which mediates drug resistance in many types of cells, depends on energy provided by ATP hydrolysis. Here, a retrovirus encoding a shRNA targeting the ATP-binding domain of this protein was used to screen for highly efficient agents that could reverse drug resistance and improve cell sensitivity to drugs, thus laying the foundation for further studies and ...

Early diagnosis is vital for effective treatment of oral squamous cell carcinoma (OSCC). The optimal time for clinical intervention is prior to malignancy when patients present with oral potentially malignant lesions such as leukoplakia or erythroplakia. Transformation rates for oral dysplasia vary greatly and more rigorous methods are needed to predict the malignant potential of oral lesions. ...