Influence of GPRC5A-Regulated ABCB1 Expression on Lung Adenocarcinoma Proliferation

Objective

Aberrant expression of ATP binding cassette subfamily B member 1 (ABCB1) plays a key role in several cancers. However, influence of G protein coupled receptor family C group 5 type A (GPRCSA)-regulated ABCB1 expression on lung adenocarcinoma proliferation remains unclear. Therefore, this study investigated the effect of GPRC5A regulated ABCB1 expression on the proliferation of lung adenocarcinoma.

Methods

ABCBI expressions in lung adenocarcinoma cell lines, human lung adenocarcinoma tissues, and tracheal epithelial cells and lung tissues of GPRC5A knockout mice and wild-type mice were analyzed with RT-PCR, Western blot, or immunohistochemical analysis. Cell counting kit-8 assay was performed to analyze the sensitivity of tracheal epithelial cells from GPRC5A knockout mice to chemotherapeutic agents. Subcutaneous tumor formation assay was performed to confirm whether down-regulation of ABCBI could inhibit the proliferation of lung adenocarcinoma in vivo. To verify the potential regulatory relationship between GPRCS A and ABCB1, immunofluorescence and immunoprecipitation assays were performed.

Results

ABCB1 expression was up-regulated in lung adenocarcinoma cell lines and human lung adenocarcinoma tissues. ABCBI expression in the tracheal epithelial cells and lung tissues of GPRC5A deficient mice was higher than that in the wild type mice. Tracheal epithelial cells of GPRC5A knockout mice were much more sensitive to tariquidar and doxorubicin than those of GPRC5A wild type mice. Accordingly, 28 days after injection of the transplanted cells, the volume and weight of lung tumor in ABCBI knockout cell-transplanted GPRCS A^-/C57BL/6 mice were significantly smaller than those in wild type cell-transplanted mice (P = 0.0043, P = 0.0060). Furthermore, immunofluorescence and immunoprecipitation assays showed that GPRC5A regulated ABCBI expression by direct binding.

Conclusion

GPRC5A reduces lung adenocarcinoma proliferation via inhibiting ABCBI expression. The pathway by which GPRC5A regulates ABCBI expression needs to be investigated.