LAPTM4B

Lysosomal-associated transmembrane protein 4B is a is_associated_with::protein that in humans is encoded by the LAPTM4B is_associated_with::gene.

LAPTM4B protein contains a is_associated_with::lysosome localization motif and localizes on late is_associated_with::endosomes and lysosomes.

Clinical significance
Increased expression of LAPTM4B has been found in breast, liver, lung, ovarian, uterine, gastric cancers. Elevated LAPTM4B level contributes to is_associated_with::chemotherapy resistance in is_associated_with::breast cancer. It was found that overexpression of LAPTM4B causes is_associated_with::anthracyclines (is_associated_with::doxorubicin, is_associated_with::daunorubicin, and is_associated_with::epirubicin) resistance by retaining drug in the cytoplasm and decreasing nuclear localization of drug and drug induced DNA damage.

In 2011, the same group reported that LAPTM4B also promotes is_associated_with::autophagy, a cell survival mechanism mediated by lysosomes. LAPTM4B promotes autophagy and renders tumor cells resistant to metabolic and genotoxic stress and results in more rapid tumor growth.

Based on these findings, LAPTM4B can be utilized to be a therapeutic target to prevent chemotherapy resistance or a marker to identify the patients who will not benefit from anthracyclines.