Cytokines-activated nuclear IKKα-FAT10 pathway induces breast cancer tamoxifen-resistance

Endocrine therapy that blocks estrogen signaling is the most effective treatment for patients with estrogen receptor positive(ER+)breast cancer.However,the efficacy of agents such as tamoxifen(Tam)is often compromised by the development of resistance.Here we report that cytokines-activated nuclear IKKαconfers Tam resistance to ER+breast cancer by inducing the expression of FAT10,and that the expression of FAT10 and nuclear IKKαin primary ER+human breast cancer was correlated with lymphotoxinβ(LTB)expression and significantly associated with relapse and metastasis in patients treated with adjuvant mono-Tam.IKKαactivation or enforced FAT10 expression promotes Tam-resistance while loss of IKKαor FAT10 augments Tam sensitivity.The induction of FAT10 by IKKαis mediated by the transcription factor Pax5,and coordinated via an IKKα-p53-miR-23a circuit in which activation of IKKαattenuates p53-directed repression of FAT10.Thus,our findings establish IKKα-to-FAT10 pathway as a new therapeutic target for the treatment of Tam-resistant ER+breast cancer.

AP4 induces JNK1 and a miR-22-3p/FOSL1 feed-forward loop to activate AP-1 and promote colorectal cancer metastasis

Dear Editor,Colorectal cancer(CRC)is the third most deadly can-cer worldwide[1].The mortality of CRC has remained high due to limited treatment options for metastatic CRC(mCRC)[2].Epithelial-mesenchymal transition(EMT)is an important contributor to mCRC[2].The c-MYC proto-oncogene(MYC)-induced transcription factor AP4(TFAP4/AP4)isadriverofEMT,therebypresumablyfacil-itates mCRC[3,4].The mitogen-activated protein kinase(MAPK)/c-JunN-terminalkinase(JNK)/activatorprotein-1(AP-1)pathway has been implicated in the regulation of EMT and mCRC[5].

The p53/miR-34 axis in development and disease

The tumor suppressor p53 is one of the most frequently mutated genes in human cancers. MicroRNAs （miRNAs） are small non-protein coding RNAs that regulate gene expression on the post-transcriptional level. Recently, it was shown that p53 regulates the expression of several miRNAs, thereby representing an important mechanism of p53 signaling. Several independent studies identified the members of the miR-34 family as the most prevalent p53-induced miRNAs, miR-34s are frequently silenced in variety of tumor entities, suggesting that they are important tumor suppressors. Indeed, ectopic expression of miR-34s inhibits proliferation, epithelial to mes- enchymat transition, migration, invasion, and metastasis of various cancer celt entities. Moreover, delivery or re-expression of miR-34 leads to notable repression of tumor growth and metastasis in cancer mouse models, and may therefore represent an efficient strategy for future cancer therapeutics. Besides their crucial functions in cancer, members of the miR-34 family also play important roles in spermatogenesis, stem cell differentiation, neuronal development, aging, and cardiovascular functions. Consequently, miR-34 has also been implicated in various non-cancerous diseases, such as brain disorders, osteoporosis, and cardiovascular complications.