Lymphangioleiomyomatosis (LAM), a rare disease of women, is associated with cystic lung destruction resulting from the proliferation of abnormal smooth muscle-like LAM cells with mutations in the tuberous sclerosis complex (TSC) genes <i>TSC1</i> and/or <i>TSC2</i> The mutant genes and encoded proteins are responsible for activation of the mechanistic target of rapamycin (mTOR), which is inhibited by sirolimus (rapamycin), a drug used to treat LAM.
In addition, recent data confirm the potential of next-generation sequencing to detect low-prevalence mutations in tuberous sclerosis (TSC) genes in sporadic LAM.
LAM is caused by inactivating mutations in the tuberous sclerosis complex (TSC) genes, resulting in hyperactivation of mechanistic/mammalian target of rapamycin complex 1 (mTORC1).
Moreover, rapamycin-enhanced migration of TSC2-null cells was inhibited by the uPA inhibitor UK122, dexamethasone, and a FOXO inhibitor. uPA-knock-out mice developed fewer and smaller TSC2-null lung tumors, and introduction of uPA shRNA in tumor cells or amiloride-induced uPA inhibition reduced tumorigenesis <i>in vivo</i> These findings suggest that interference with the uPA-dependent pathway, when used along with rapamycin, might attenuate LAM progression and potentially other TSC-related disorders.
Our results illuminate the basis for lymphangioleiomyomatosis growth and demonstrate the therapeutic potential of targeting Syk in this and other settings driven by TSC genetic mutation.<i></i>.
Mutations in tuberous sclerosis (TSC) genes cause the genetic disorder TSC, as well as other neoplasms, including lymphangioleiomyomatosis (LAM) and angiomyolipomas (AMLs).
However, our study indicates that a fraction of sporadic LAM can be a TSC1 disease; therefore, both TSC genes should be examined, even for patients with sporadic LAM.
We previously found TSC2 loss of heterozygosity in 7 of 13 (54%) of angiomyolipomas from sporadic LAM patients, suggesting that LAM and TSC could have a common genetic basis.