Cisplatin resistance is a major challenge for advanced head and neck cancer (HNC). Understanding the underlying mechanisms and developing effective strategies against cisplatin resistance are highly desired in the clinic. However, how tumor stroma modulates HNC growth and chemoresistance is unclear. We show that cancer-associated fibroblasts (CAFs) are intrinsically resistant to cisplatin and have an active role in regulating HNC cell survival and proliferation by delivering functional miR-196a from CAFs to tumor cells via exosomes. Exosomal miR-196a then binds novel targets, CDKN1B and ING5, to endow HNC cells with cisplatin resistance. Exosome or exosomal miR-196a depletion from CAFs functionally restored HNC cisplatin sensitivity. Importantly, we found that miR-196a packaging into CAF-derived exosomes might be mediated by heterogeneous nuclear ribonucleoprotein A1 (hnRNPA1). Moreover, we also found that high levels of plasma exosomal miR-196a are clinically correlated with poor overall survival and chemoresistance. The present study finds that CAF-derived exosomal miR-196a confers cisplatin resistance in HNC by targeting CDKN1B and ING5, indicating miR-196a may serve as a promising predictor of and potential therapeutic target for cisplatin resistance in HNC.

Head and neck cancer (HNC) is one of the most common deadly diseases worldwide. An increasing number of studies have recently focused on the malignant functions of cancer-associated fibroblasts (CAFs) in numerous cancers. However, the underlying mechanisms by which CAF-derived exosomes promote tumor progression need to be further elucidated. This study aims to determine whether the loss of specific miRNAs in CAF-derived exosomes may be involved in the malignant transformation of HNC. MiRNA array and real-time PCR assays were used to analyze the differential expression of miRNAs in exosomes from normal fibroblasts (NFs) and CAFs. Cell proliferation, EdU incorporation, colony formation, apoptosis, cell cycle distribution and xenograft assays were performed to examine the effects of miR-3188 on HNC in vitro and in vivo. Real-time PCR, western blotting and luciferase reporter assays were used to identify the target genes of miR-3188. Furthermore, tumor-bearing mouse models were used to prove the potential therapeutic value of miR-3188-loaded exosomes in HNC. Our results showed that miR-3188 expression is reduced in exosomes and their parental CAFs from HNC tissues. In addition, miR-3188 can be transferred from fibroblasts to HNC cells by exosomes. Further exploration demonstrated that exosomal miR-3188 can influence the proliferation and apoptosis of HNC cells by directly targeting B-cell lymphoma 2 (BCL2) in vitro and in vivo. More importantly, we also found that miR-3188-loaded exosomes significantly inhibited tumor growth in vivo. Our findings revealed that CAF-derived exosomes contain lower miR-3188 levels than NFs, and the loss of miR-3188 in exosomes contributes to the malignant phenotypes of HNC cells through the derepression of BCL2. Furthermore, these data suggest the potential therapeutic value of exosomal miR-3188 for inhibiting HNC growth.

Recently, the glymphatic system has been recognised as an important ‘waste solutes transport channel’ within the brain.1 Studies have shown that blockage of the glymphatic system leads to increased beta-amyloid deposits, accelerating the onset and progression of Alzheimer’s disease (AD).1 2 Given that cervical lymph nodes receive cerebrospinal fluid from the brain’s glymphatic system,3 4 we speculated that decompression of the lymphatic trunk and cervical lymphatic–venous anastomosis (LVA) could facilitate the flow of cerebrospinal fluid in the cranial glymphatic system, potentially accelerating the clearance of harmful beta-amyloid and tau proteins. We collaborated with surgeons who specialise in LVA supermicrosurgery for maxillofacial tumours and lymphoedema to develop a procedure to relieve the blockage of the glymphatic system. This surgery employs supermicrosurgery techniques to create LVA connecting the bilateral cervical, deep lymphatic vessels to the veins, resulting in lymphatic trunk decompression, which allows the lymph fluid in the high-pressure lymphatic vessels to flow into the low-pressure venous system. The goal of the minimally invasive surgery is to enhance the removal of proteins, such as beta-amyloid and tau, from the brain’s lymphatic systems to the maxillofacial lymphatic vessels, unclogging protein blockages within the brain. This extracranial procedure is safer than intracranial approaches. Following a thorough assessment of the safety and potential efficacy of the procedure, and securing ethics approval from the Ethics Committees of the Shanghai Mental Health Center and Shanghai Ninth People’s Hospital, we initiated an investigator-initiated trial of the ‘Cervical Shunting to Unclog cerebral Lymphatic Systems (CSULS) surgical procedure’ (registration number: ChiCTR2400084617).