{"database":"biostudies-literature","file_versions":[],"scores":null,"additional":{"submitter":["Bouznad N"],"funding":["Deutsche Forschungsgemeinschaft"],"pagination":["1143"],"full_dataset_link":["https://www.ebi.ac.uk/biostudies/studies/S-EPMC9954576"],"repository":["biostudies-literature"],"omics_type":["Unknown"],"volume":["15(4)"],"pubmed_abstract":["Tumor-associated hypoxia, i.e., decreased availability of oxygen, results in a poor clinical outcome since it promotes EMT, metastasis, and chemotherapy-resistance. We have previously identified p53 and its target miR-34a, as critical determinants of the effect of hypoxia on colorectal cancer (CRC). Here, we aimed to characterize mechanisms that contribute to the selective advantage of cells with loss of p53/miR-34a function in a hypoxic environment. Using in silico prediction, we identified XBP-1 and IRE1A as potential miR-34a targets. IRE1A and XBP-1 are central components of the unfolded protein response that is activated by ER stress, which is also induced in tumor cells as a response to harsh conditions surrounding tumors such as hypoxia and a limited supply of nutrients. Here we characterized the XBP-1(S) transcription factor and its regulator IRE1A as direct, conserved miR-34a targets in CRC cells. After hypoxia and DNA damage, IRE1A and XBP-1 were repressed by p53 in a miR-34a-dependent manner, whereas <i>p53</i>-deficient cells showed induction of IRE1A and XBP-1(S). Furthermore, miR-34a expression was directly suppressed by XBP-1(S). In <i>p53</i>-deficient CRC cells, hypoxia-induced EMT, migration, invasion, metastases formation, and resistance to 5-FU were dependent on IRE1A/XBP-1(S) activation. Hypoxia-induced autophagy was identified as an XBP-1(S)-dependent mediator of 5-FU resistance and was reversed by ectopic miR-34a expression. The HIF1A/IRE1A/XBP-1(S)/p53/miR-34a feedback loop described here represents a central regulator of the response to hypoxia and ER stress that maintains cellular homeostasis. In tumors, the inactivation of <i>p53</i> and <i>miR-34a</i> may result in IRE1A/XPB-1(S)-mediated EMT and autophagy, which ultimately promotes metastasis and chemoresistance."],"journal":["Cancers"],"pubmed_title":["miR-34a and IRE1A/XBP-1(S) Form a Double-Negative Feedback Loop to Regulate Hypoxia-Induced EMT, Metastasis, Chemo-Resistance and Autophagy."],"pmcid":["PMC9954576"],"funding_grant_id":["He 2710/15-1"],"pubmed_authors":["Hermeking H","Rokavec M","Bouznad N","Oner MG"],"additional_accession":[]},"is_claimable":false,"name":"miR-34a and IRE1A/XBP-1(S) Form a Double-Negative Feedback Loop to Regulate Hypoxia-Induced EMT, Metastasis, Chemo-Resistance and Autophagy.","description":"Tumor-associated hypoxia, i.e., decreased availability of oxygen, results in a poor clinical outcome since it promotes EMT, metastasis, and chemotherapy-resistance. We have previously identified p53 and its target miR-34a, as critical determinants of the effect of hypoxia on colorectal cancer (CRC). Here, we aimed to characterize mechanisms that contribute to the selective advantage of cells with loss of p53/miR-34a function in a hypoxic environment. Using in silico prediction, we identified XBP-1 and IRE1A as potential miR-34a targets. IRE1A and XBP-1 are central components of the unfolded protein response that is activated by ER stress, which is also induced in tumor cells as a response to harsh conditions surrounding tumors such as hypoxia and a limited supply of nutrients. Here we characterized the XBP-1(S) transcription factor and its regulator IRE1A as direct, conserved miR-34a targets in CRC cells. After hypoxia and DNA damage, IRE1A and XBP-1 were repressed by p53 in a miR-34a-dependent manner, whereas <i>p53</i>-deficient cells showed induction of IRE1A and XBP-1(S). Furthermore, miR-34a expression was directly suppressed by XBP-1(S). In <i>p53</i>-deficient CRC cells, hypoxia-induced EMT, migration, invasion, metastases formation, and resistance to 5-FU were dependent on IRE1A/XBP-1(S) activation. Hypoxia-induced autophagy was identified as an XBP-1(S)-dependent mediator of 5-FU resistance and was reversed by ectopic miR-34a expression. The HIF1A/IRE1A/XBP-1(S)/p53/miR-34a feedback loop described here represents a central regulator of the response to hypoxia and ER stress that maintains cellular homeostasis. In tumors, the inactivation of <i>p53</i> and <i>miR-34a</i> may result in IRE1A/XPB-1(S)-mediated EMT and autophagy, which ultimately promotes metastasis and chemoresistance.","dates":{"release":"2023-01-01T00:00:00Z","publication":"2023 Feb","modification":"2025-05-29T19:42:55.413Z","creation":"2025-05-29T19:42:55.413Z"},"accession":"S-EPMC9954576","cross_references":{"pubmed":["36831485"],"doi":["10.3390/cancers15041143"]}}