Abstract
Deficiency or mutation in the p53 tumor suppressor gene commonly occurs in human cancer and can contribute to disease progression and chemotherapy resistance. Currently, although the ...pro-survival or pro-death effect of autophagy remains a controversial issue, increasing data seem to support the idea that autophagy facilitates cancer cell resistance to chemotherapy treatment. Here we report that 5-FU treatment causes aberrant autophagosome accumulation in HCT116 p53
−/−
and HT-29 cancer cells. Specific inhibition of autophagy by 3-MA, CQ or small interfering RNA treatment targeting Atg5 or Beclin 1 can potentiate the re-sensitization of these resistant cancer cells to 5-FU. In further analysis, we show that JNK activation and phosphorylation of Bcl-2 are key determinants in 5-FU-induced autophagy. Inhibition of JNK by the compound SP600125 or JNK siRNA suppressed autophagy and phosphorylation of c-Jun and Bcl-2 but increased 5-FU-induced apoptosis in both HCT116 p53
−/−
and HT29 cells. Taken together, our results suggest that JNK activation confers 5-FU resistance in HCT116 p53
−/−
and HT29 cells by promoting autophagy as a pro-survival effect, likely via inducing Bcl-2 phosphorylation. These results provide a promising strategy to improve the efficacy of 5-FU-based chemotherapy for colorectal cancer patients harboring a p53 gene mutation.
Cancer stem cells (CSCs) are a subpopulation of chemoresistant cells that play a critical role in disease recurrence following chemotherapy. It has been reported that microRNA-133b (miR-133b) acts as ...a tumor suppressor in colorectal cancer (CRC). However, whether miR-133b is associated with CRC stemness and chemoresistance is not clear. In this study, we report that miR-133b is downregulated in colorectal spheroids, which are enriched with CSCs and display stem cell-like characteristics, including upreulation of CSCs surface markers and elevated chemoresistance. Additionally, miR-133b overexpression reduces CRC stemness and overrides chemoresistance to 5-Fluorouracil (5-FU) and oxaliplatin (OXP), indicating a negative role of miR-133b in regulating CRC stemness and chemoresistance. Moreover, miR-133b directly targets and suppresses the expression of disruptor of telomeric silencing 1-like (DOT1L), an exclusive H3K79 methyltransferase. Furthermore, miR-133b overexpression suppresses DOT1L-mediated H3K79me2 modification of stem cell genes, which is consistent with their downregulated transcription. More importantly, DOT1L restoration abrogates the suppressive effects of miR-133b on CRC stemness and chemoresistance, hence demonstrating that miR-133b regulates CRC stemness and chemoresistance through targeting DOT1L. Overall, these results imply that miR-133b might represent a novel therapeutic target in interfering CRC stemness and chemoresistance.
•miR-133b level is downregulated in colorectal spheroids.•miR-133b reduces stemness and chemoresistance in colorectal spheroids.•miR-133b targets and suppresses DOT1L-mediated H3K79me2 modification and transcription of stem cell genes.•DOT1L restoration abrogates miR-133b effects on stemness and chemoresistance in colorectal spheroids.
MiR-195-5p has been shown to have a regulatory role in a variety of cancers. Its influence on colorectal cancer (CRC), however, has never been evaluated. In the present study, we found that ...miR-195-5p expression was significantly decreased as compared to paired, tumor-adjacent normal colorectal tissues. We demonstrated that miR-195-5p inhibited the stem-like capacity of CRC cells. We established 5-FU-resistant SW620 and HT-29 cell lines and performed a variety of functional assays following exposure to miR-195-5p and anti-miR-195-5p. In 5-FU-resistant cells, expression of miR-195-5p, P-gp and ABCG2 was decreased. MiR-195-5p significantly increased cancer cell apoptosis and decreased tumor sphere formation. In order to determine the mechanism by which miR-195-5p reduced CRC cell stemness and chemoresistance, we first identified potential targets of miR-195-5p. The 3′ UTR of Notch signaling proteins Notch2 and RBPJ, which are essential genes in CRC cell stemness and chemoresistance, possessed double putative binding sites of miR-195-5p. qRT-PCR and western blot assays demonstrated significant decreases in Notch2 and RBPJ when CRC cell lines were exposed to miR-195-5p and significant increases when exposed to anti-miR-195-5p. These findings indicate that miR-195-5p has the potential to improve standard therapeutic approaches to CRC.
Chemoresistance remains the main obstacle limiting the treatment of osteosarcoma, seriously affecting the prognosis of adolescent patients with osteosarcoma. Recently, long non-coding RNAs (lncRNAs) ...were reported to be involved in chemoresistance, while the mechanisms of lncRNAs underlying osteosarcoma resistance to chemotherapy remain elusive. Here, LINC00520 was identified as a novel cisplatin resistance-related lncRNA in osteosarcoma, and its high expression was associated with poor prognosis of osteosarcoma patients. Functionally, LINC00520 could potentiate osteosarcoma resistance to cisplatin in vitro and in vivo. Mechanistically, LINC00520 bound to ENO1 and upregulated ENO1 protein expression by blocking FBXW7-mediated ENO1 ubiquitination and proteasomal degradation, thereby promoting glycolysis and ultimately inducing cisplatin resistance in osteosarcoma. Furthermore, METTL3 could stabilize and upregulate LINC00520 in an m6A-YTHDF2-dependent manner in osteosarcoma. This study proposes a novel lncRNA-driven mechanism for cisplatin resistance in osteosarcoma, and offers a promising therapeutic strategy for reversing chemoresistance in osteosarcoma by targeting the METTL3/LINC00520/ENO1/glycolysis axis.Chemoresistance remains the main obstacle limiting the treatment of osteosarcoma, seriously affecting the prognosis of adolescent patients with osteosarcoma. Recently, long non-coding RNAs (lncRNAs) were reported to be involved in chemoresistance, while the mechanisms of lncRNAs underlying osteosarcoma resistance to chemotherapy remain elusive. Here, LINC00520 was identified as a novel cisplatin resistance-related lncRNA in osteosarcoma, and its high expression was associated with poor prognosis of osteosarcoma patients. Functionally, LINC00520 could potentiate osteosarcoma resistance to cisplatin in vitro and in vivo. Mechanistically, LINC00520 bound to ENO1 and upregulated ENO1 protein expression by blocking FBXW7-mediated ENO1 ubiquitination and proteasomal degradation, thereby promoting glycolysis and ultimately inducing cisplatin resistance in osteosarcoma. Furthermore, METTL3 could stabilize and upregulate LINC00520 in an m6A-YTHDF2-dependent manner in osteosarcoma. This study proposes a novel lncRNA-driven mechanism for cisplatin resistance in osteosarcoma, and offers a promising therapeutic strategy for reversing chemoresistance in osteosarcoma by targeting the METTL3/LINC00520/ENO1/glycolysis axis.
Despite considerable progress in cancer treatment options, resistance to chemotherapeutic drugs remains a significant challenge. This review focuses on Berberine (BBR), an isoquinoline alkaloid found ...in various medicinal plants, which has garnered attention in the field of oncology for its anticancer potential either alone or in combination with other compounds and its ability to modulate chemoresistance, acting as a natural chemosensitizer. BBR's ability to modulate chemoresistance is attributed to its diverse mechanisms of action, including inducing DNA breaks, inhibition of drug efflux pumps, modulation of apoptosis and necroptosis, downregulating multidrug resistance genes, enhancing immune response, suppressing angiogenesis and targeting multiple pathways within cancer cells, including protein kinase B/mammalian target of rapamycin (Akt/mTOR), epidermal growth factor receptor (EGFR), mitogen-activated protein kinase (MAPK), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), poly(ADP-ribose) polymerase (PARP1), janus kinase/signal transducers and activators of transcription (JAK-STAT), Wnt/β-catenin etc. Moreover, BBR, in combination with other compounds, also offers a promising approach to cancer therapy, enforcing its broad-spectrum anticancer effects. Therefore, this review aims to elucidate the intricate mechanism of action of BBR in combinatorial therapy as a potential chemosensitizer to increase the efficiency of several drugs, including cisplatin, doxorubicin, lapatinib, tamoxifen, irinotecan, niraparib, etc. in various cancers. Additionally, this review briefly covers the origin and biological activities of BBR, exploring the specific actions underlying its anticancer effects. Further, pharmacokinetic properties of BBR are also discussed, providing insight into its therapeutic potential and optimization of its use in cancer treatment.
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•Chemoresistance presents a significant challenge.•Berberine regulates various mechanisms linked to chemoresistance.•Berberine can be a promising candidate for combination therapy.
Overcoming intrinsic and acquired drug resistance is a major challenge in treating cancer patients because chemoresistance causes recurrence, cancer dissemination and death. This review summarizes ...numerous molecular aspects of multi-resistance, including transporter pumps, oncogenes (EGFR, PI3K/Akt, Erk and NF-κB), tumor suppressor gene (p53), mitochondrial alteration, DNA repair, autophagy, epithelial-mesenchymal transition (EMT), cancer stemness, and exosome. The chemoresistance-related proteins are localized to extracellular ligand, membrane receptor, cytosolic signal messenger, and nuclear transcription factors for various events, including proliferation, apoptosis, EMT, autophagy and exosome. Their cross-talk frequently appears, such as the regulatory effects of EGFR-Akt-NF-κB signal pathway on the transcription of Bcl-2, Bcl-xL and survivin or EMT-related stemness. It is essential for the realization of the target, individualized and combine therapy to clarify these molecular mechanisms, explore the therapy target, screen chemosensitive population, and determine the efficacy of chemoreagents by cell culture and orthotopic model.
Cancer-associated fibroblasts (CAFs) are the predominant stromal cells in the microenvironment and play important roles in tumor progression, including chemoresistance. However, the response of CAFs ...to chemotherapeutics and their effects on chemotherapeutic outcomes are largely unknown. In this study, we showed that epirubicin (EPI) treatment triggered ROS which initiated autophagy in CAFs, TCF12 inhibited autophagy flux and further promoted exosome secretion. Inhibition of EPI-induced reactive oxygen species (ROS) production with N-acetyl-L-cysteine (NAC) or suppression of autophagic initiation with short interfering RNA (siRNA) against ATG5 blunted exosome release from CAFs. Furthermore, exosome secreted from EPI-treated CAFs not only prevented ROS accumulation in CAFs but also upregulated the CXCR4 and c-Myc protein levels in recipient ER+ breast cancer cells, thus promoting EPI resistance of tumor cells. Together, the current study provides novel insights into the role of stressed CAFs in promoting tumor chemoresistance and reveal a new function of TCF12 in regulating autophagy impairment and exosome release.
•Stromal TCF12 inhibits autophagy flux and promotes exosome secretion from CAFs with epirubicin (EPI) treatment.•EPI-induced ROS production and autophagy initiation in CAFs is required for TCF12-mediated exosome secretion.•Exosome secretion can scavenge EPI-induced reactive oxygen species (ROS) production in CAFs.•Exosomes released from EPI-treated CAFs promote EPI resistance of ER+ breast cancer cells.
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