ATF2 contributes to cisplatin resistance in non‐small cell lung cancer and celastrol induces cisplatin resensitization through inhibition of JNK/ATF2 pathway

Abstract

ATF2 is a transcription factor involved in stress and DNA damage. A correlation between ATF2 JNK-mediated activation and resistance to damaging agents has already been reported. The purpose of the present study was to investigate whether ATF2 may have a role in acquired resistance to cisplatin in non-small cell lung cancer (NSCLC). mRNA and protein analysis on matched cancer and corresponding normal tissues from surgically resected NSCLC have been performed. Furthermore, in NSCLC cell lines, ATF2 expression levels were evaluated and correlated to platinum (CDDP) resistance. Celastrol-mediated ATF2/cJUN activity was measured. High expression levels of both ATF2 transcript and proteins were observed in lung cancer specimens (p << 0.01, Log 2 (FC) 5 14.7). CDDP-resistant NSCLC cell lines expressed high levels of ATF2 protein. By contrast, Celastrol-mediated ATF2/cJUN functional inhibition restored the response to CDDP. Moreover, ATF2 protein activation correlates with worse outcome in advanced CDDP-treated patients. For the first time, it has been shown NSCLC ATF2 upregulation at both mRNA/protein levels in NSCLC. In addition, we reported that in NSCLC cell lines a correlation between ATF2 protein expression and CDDP resistance occurs. Altogether, our results indicate a potential increase in CDDP sensitivity, on Celastrolmediated ATF2/cJUN inhibition. These data suggest a possible involvement of ATF2 in NSCLC CDDP-resistance.Non-small cell lung cancer (NSCLC) is characterized by high incidence and mortality rate worldwide, being the most common subtypes represented by adenocarcinoma and squamous cell carcinoma. 1 Platinum-based chemotherapy in combination with other cytotoxic agents such as Gemcitabine, taxanes and vinorelbine represented the standard of care for unselected patients with advanced NSCLC. Recently, in nonsquamous histology, the combination of cisplatin (CDDP) and pemetrexed showed superior activity. 2,3 However, in chemotherapy-treated NSCLC, the duration of response is relatively short due to primary or acquired resistance to chemotherapy. 4 Patients with advanced disease may not derive any benefit from first-line chemotherapy, while they face significant treatment-related side effects. Consequently, it appears a logical approach to investigate alternative ways to increase the effectiveness outcomes of chemotherapy, through the identification of molecular features suggestive of a better therapeutic ratio.Activating transcription factor 2 (ATF2) is a member of the basic helix-loop-helix (b-ZIP) transcription factor family, whose transcriptional activities are mediated by stressactivated kinases JNK/p38 and activated by phosphorylation on threonine residues. 5,6 Independent of its transcriptional activity, ATF2 also plays an important role in the DNA damage response and in the regulation of intra-S-phase checkpoint (reviewed in Ref. 7). Several studies reported a correlation between ATF2/JNK-mediated activation and resistance to DNA damaging agents. Hayakawa et al. showed that stable expression of ATF...

miR‑145‑5p inhibits epithelial‑mesenchymal transition via the JNK signaling pathway by targeting MAP3K1 in non‑small cell lung cancer cells

“…It was previously demonstrated that protein 4.1N, a member of the protein 4.1 family, was able to suppress metastasis by inactivating JNK-c-Jun signaling pathway in NSCLC (34). Celastrol induces cisplatin re-sensitization through inhibition of the JNK/activating transcription factor 2 signaling pathway in NSCLC (35). JNK signaling mediates EPH receptor A2-dependent tumor cell proliferation, motility and cancer stem cell-like properties in NSCLC cells (36).…”

Dasatinib modulates sensitivity to pemetrexed in malignant pleural mesothelioma cell lines

“…For immunofluorescence analyses, cells were grown on glass coverslips following the procedure previously described [36], except for fixation method employed in this study, consisting in 4% paraformaldehyde/PBS. Confocal series images were taken on an inverted Zeiss LSM510 microscope equipped with a Plan-Apochromat 63X/1.4 oil immersion Ph 3 objective (Oberkochen, Germany).…”

“…Each sample was quantified using spectrophotometer and 1 μg of RNA was retrotranscribed as previously described [36]. Genomic DNA contamination was removed by DNAse I treatment, according to manufacturer's protocol (Ambion, Life Technologies, Carlsbad, CA, USA).…”

Metabolomics profiles delineate uridine deficiency contributes to mitochondria-mediated apoptosis induced by celastrol in human acute promyelocytic leukemia cells

“…Recently, its anti-cancer [11–14] and chemotherapy sensitization activities [15–17] were increasingly focused. However, the anti-leukemia effect of celastrol is rarely reported, especially on APL.…”