Search

Purpose: The long non-coding RNA MALAT1 is a predictive marker in several solid tumors with highly conserved sequences. However, the role of non-coding RNA in development of laryngeal or hypopharyngeal cancer remains unclear. Methods: Tumor tissues and adjacent non-cancer tissues of 24 patients were collected. We detected the expression of MALAT1 in laryngeal cancer tissues and hypopharyngeal cancer tissues. Moreover, we developed a MALAT1 silencing model in human laryngeal tumor cells by transfecting MALAT1 small interfering RNA into human laryngeal carcinoma cell line Hep-2 and pharyngeal carcinoma cell line FaDu with Lipofectamine 2000 system. Cell cycle analysis, Cell Counting Kit-8 assay, Transwell assay, quantitative reverse transcription PCR, and wound-healing assays were performed to evaluate the impact of MALAT1 depletion on laryngeal or hypopharyngeal cancer cell's growth, proliferation, apoptosis, invasion and migration. Results: MALAT1 was significantly up-regulated in laryngeal and hypopharyngeal carcinoma cells. MALAT1 down-regulation induced the increased apoptosis of both cell lines and suppressed cells' proliferation. Cells were arrested in G1/G2 phase and cells of S phase were significantly decreased. Down-regulation of MALAT1 expression can also inhibit the migration and invasion of laryngeal squamous cell carcinoma cell (Hep-2) and hypopharyngeal cancer cell (FaDu). Conclusion: In summary, our deactivation model of MALAT1 disentangled the active function of it as a regulator of gene expression governing the hallmarks of laryngeal and hypopharyngeal cancer. Blocking this long non-coding RNA may restrain the development of laryngeal cancer. [ABSTRACT FROM AUTHOR]

Although poly (ADP-ribose) polymerase (PARP) inhibitors, as anti-tumor drugs targeting the DNA damage response (DDR), have been used for the therapy of various tumors, few researches reported their effect on laryngeal squamous cell carcinoma (LSCC). Here, we first discovered that the PARP-1/2 inhibitor Niraparib could simultaneously induce cell growth inhibition and autophagy in LSCC TU212 and TU686 cells. Niraparib decelerated cell cycle of LSCC by arresting G1 phase and preventing the cells from entering S phase. DNA lesions were also observed upon Niraparib treatment as evidenced by the accumulation of γH2AX and abatement of pRB expression. In addition, autophagy generation was confirmed by the observation of autophagosomes, LC3-positive autophagy-like vacuoles, and obvious conversion of LC3-I to LC3-II. Moreover, blocking autophagy enhanced Niraparib-induced growth inhibition and DNA lesions. Further studies suggested that autophagy suppression could obstruct the activation of checkpoint kinase 1 (Chk1) through elevating proteasomal activity and then impair the capacity of homologous recombination (HR), thereby improving the anti-LSCC efficiency of Niraparib. Collectively, these findings suggested that simultaneous targeting of Niraparib and autophagy might be a promising therapeutic schedule for LSCC in clinic. [ABSTRACT FROM AUTHOR]

Laryngeal squamous cell carcinoma (LSCC), one of the most common malignancies in the head and neck, has poor prognosis and high mortality. The need of novel and effective treatment for LSCC is urgent. Asparaginase, an enzyme-depriving asparagine, has been employed for the treatment of various cancers. In this study, we reported for the first time that asparaginase could induce remarkable cytotoxicity and caspase-dependent apoptosis in human LSCC Tu212 and Tu686 cells. Meanwhile, autophagy was triggered by asparaginase in LSCC cells, which was confirmed by accumulation of autophagosomes and the conversion of light chain 3-I (LC3-I) to LC3-II. Importantly, inhibition of autophagy by chloroquine (CQ) significantly enhanced asparaginase-induced cytotoxicity, indicating that autophagy has a cytoprotective role in asparaginase-treated LSCC cells. Meanwhile, we found that mitochondrial-originated reactive oxygen species (ROS) participated in asparaginase-induced autophagy and cytotoxicity. N-acetyl-L-cysteine (NAC), a common antioxidant, was employed to scavenge ROS, and our results demonstrated that NAC could significantly block asparaginase-induced autophagy and attenuate asparaginase-induced cytotoxicity, indicating that intracellular ROS played a crucial role in asparagine deprivation therapy. Furthermore, western blot analysis showed that asparaginase-induced autophagy was mediated by inactivation of Akt/mTOR and activation of the Erk signaling pathway in Tu212 and Tu686 cells. Therefore, these results indicated the protective role of autophagy in asparaginase-treated LSCC cells and provided a new attractive therapeutic strategy for LSCC by asparaginase alone or in combination with autophagic inhibitors. [ABSTRACT FROM AUTHOR]

Laryngeal squamous cell carcinoma (LSCC), one of the most common malignant solid tumors in the world, has a high rate of mortality, recurrence, and metastasis. Recombinant human arginase (rhArg) recently has been developed in arginine deprivation therapy for a number of malignant tumors. In the present study, we observed that rhArg triggered significant cytotoxicity in human laryngeal squamous cell carcinoma Tu212 cells. Meanwhile, we observed that rhArg simultaneously activated autophagic flux in Tu212 cells, which was demonstrated by the accumulation of autophagosome and light chain 3 II (LC3-II). And, we explored the role of autophagy in cytotoxicity induced by rhArg in Tu212 cells. Autophagy inhibitors including chloroquine (CQ) and bafilomycin A1 (Baf A1) enhanced cytotoxicity induced by rhArg, implying the protective role of autophagy in rhArg-treated Tu212 cells. Moreover, Akt/mTOR signaling pathway was most possibly to participate in the rhArg-induced autophagy. Meanwhile, rhArg could upregulate the phosphorylation of ERK1/2 in a time-dependent manner. Therefore, all the results illuminated the cytoprotective role of autophagy in the treatment of rhArg in laryngeal squamous carcinoma Tu212 cells and provided a potential approach for LSCC therapy by rhArg combined with autophagy inhibitors. [ABSTRACT FROM AUTHOR]