LARS1 knockdown suppresses the biological activities of thyroid cancer cells by stimulating autophagy.

BACKGROUND

Given the elevated prevalence of thyroid cancer in China and its status as the leading malignant endocrine tumor, identifying molecular targets for intervention is critical. This study sought to define the functional significance of LARS1 in thyroid cancer pathogenesis and delineate the mechanistic pathways involved.

MATERIALS AND

METHODS

We measured LARS1 protein expression in adjacent normal and cancer tissues using immunohistochemistry. First, we knocked down LARS1 in CAL-62 and 8305 C cell lines using si-LARS1 and then inhibited autophagy using an mTOR agonist. Second, we measured cell proliferation, apoptosis rate, invasion, migration and ultrastructure using CCK-8 assay, EdU assay, flow cytometry, TUNEL staining, Transwell assay, wound healing assay and transmission electron microscopy, LC3B protein levels were evaluated by IF staining. ATG7, beclin1, P62 and TIM23 gene expression levels were measured by RT-qPCR; and LC3, ATG7, beclin1, P62 and TIM23 protein expression levels were assessed by western blot.

RESULTS

Elevated LARS1 protein expression was consistently observed in tumor specimens relative to normal counterparts (P < 0.001). Depletion of LARS1 expression resulted in a pronounced attenuation of cellular proliferation concurrent with a substantial elevation in apoptotic rates. Furthermore, the capacities of cancer cells for invasion and migration were markedly impaired following LARS1 knockdown (P < 0.001). This manipulation also led to significant enhancements in the expression levels of both the protein and mRNA encoding ATG7 and beclin1, while diminishing the levels of TIM23 and P62. A concomitant increase in the LC3-II to LC3-I ratio was also documented. Notably, the tumor-suppressive outcomes elicited by si-LARS1 were counteracted upon administration of an mTOR agonist.

CONCLUSION

LARS1 knockdown suppressed thyroid cancer cell abilities by regulating autophagy activation through mTOR inhibition in vitro.