Vorinostat enhances the therapeutic potential of Erlotinib via MAPK in lung cancer cells

BACKGROUND

Lung cancer is the second most common cancer in both men and women, with an estimated 235,760 new cases and 131,880 deaths in 2021 in the US. Despite the modern therapies being available such as radiotherapy and chemotherapy, death rates are still increasing. Erlotinib (ERL) is one of the treatment options for lung cancer, although the probability for the patients to develop resistance to ERL constrains its reliability. The aim of the present study is to assess the synergetic effect of combining ERL with vorinostat (SAHA) on the progression of lung cancer cells.

RESULTS

Adenocarcinoma alveolar basal epithelial cells (A549) were treated with either ERL, SAHA as mono drugs or with the combination of them for 24 h. Cytotoxicity assay and cell cycle analysis along with apoptosis detection were investigated. The expression profile of CDH1, TGF1, and MAPK was also assessed. Results showed an elevation in the apoptosis level in all treatments compared to WISH; the normal human amnion-derived cells. Furthermore, the treatments caused the cell cycle to arrest at G2/M, indicating its cytotoxic activity.

CONCLUSION

The combination of SAHA and ERL significantly increased the level of apoptosis in lung cancer cells. Meanwhile, this combination treatment downregulated MAPK compared to the mono drugs and the control cells, suggesting the potential role of MAPK in regulating apoptosis and cell cycle machinery in lung cancer.

Phasic alerting facilitates endogenous orienting of spatial attention: Evidence from event-related lateralizations of the EEG

Alerting has been hypothesized to affect spatial orienting either by accelerating the speed of attentional shift toward the cued target location (the accelerating hypothesis) or by enhancing the orienting effect without changing its time course (the enhancing hypothesis). To investigate the neural underpinnings of the effect of phasic alerting on endogenous orienting, we recorded the electroencephalogram (EEG) in a variant of the spatial cueing task with a tone presented 100 ms before the cue as a phasic alerting signal, and calculated cue-evoked event-related lateralizations (ERLs) providing a precise assessment of preparatory visuospatial attention. Behavioral results showed that the spatial orienting effect was increased under the phasic alerting condition, as expected. The EEG results showed that an orienting-related ERL component called a late directing attention positivity (LDAP) had shorter onset latency and larger amplitude in the alerting condition than in the no-alerting (no-tone) condition. In conclusion, phasic alerting seems to both accelerate and enhance orienting-related preparatory modulations within the ventral visual stream.

NOX4 mediates cytoprotective autophagy induced by the EGFR inhibitor erlotinib in head and neck cancer cells

Most head and neck squamous cell carcinomas (HNSCCs) overexpress epidermal growth factor receptor (EGFR) and EGFR inhibitors are routinely used in the treatment of HNSCC. However, many HNSCC tumors do not respond or become refractory to EGFR inhibitors. Autophagy, which is a stress-induced cellular self-degradation process, has been reported to reduce the efficacy of chemotherapy in various disease models. The purpose of this study is to determine if the efficacy of the EGFR inhibitor erlotinib is reduced by activation of autophagy via NOX4-mediated oxidative stress in HNSCC cells. Erlotinib induced the expression of the autophagy marker LC3B-II and autophagosome formation in FaDu and Cal-27 cells. Inhibition of autophagy by chloroquine and knockdown of autophagy pathway genes Beclin-1 and Atg5 sensitized both cell lines to erlotinib-induced cytotoxicity, suggesting that autophagy may serve as a protective mechanism. Treatment with catalase (CAT) and diphenylene iodonium (DPI) in the presence of erlotinib suppressed the increase in LC3B-II expression in FaDu and Cal-27 cells. Erlotinib increased NOX4 mRNA and protein expression by increasing its promoter activity and mRNA stability in FaDu cells. Knockdown of NOX4 using adenoviral siNOX4 partially suppressed erlotinib-induced LC3B-II expression, while overexpression of NOX4 increased expression of LC3B-II. These studies suggest that erlotinib may activate autophagy in HNSCC cells as a pro-survival mechanism, and NOX4 may play a role in mediating this effect.