Communication Between Cancer Cell Subtypes by Exosomes Contributes to Nasopharyngeal Carcinoma Metastasis and Poor Prognosis

Life Sciences Cell Biology Medicine Oncology Immunology
cell heterogeneity cell communication exosomes metastasis nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a malignant tumor originating from the epithelial lining of the nasopharynx, characterized by a distinct geographical distribution, particularly with high incidence rates in Southeast Asia and Southern China. Despite significant progress in NPC treatment in recent years, the prognosis for patients remains poor, especially for those with recurrent or metastatic NPC. Tumor heterogeneity, a common phenomenon in cancer, refers to the differences in gene expression, function, and behavior among different cell subtypes within a tumor. This heterogeneity plays a critical role in tumor initiation, progression, and treatment resistance. However, the mechanisms underlying the interactions between NPC cell subtypes and their impact on tumor metastasis remain unclear.

Exosomes are nano-sized vesicles secreted by cells, capable of carrying molecules such as proteins, RNA, and DNA, and mediating intercellular communication. In recent years, the role of exosomes in cancer has garnered significant attention, particularly in the tumor microenvironment, where exosomes can promote tumor growth, metastasis, and treatment resistance by transmitting signaling molecules. However, the role of exosomes in communication between NPC cell subtypes and their impact on tumor metastasis has not been fully investigated.

Source of the Paper

This research paper was jointly completed by authors including Hao-Jun Xie, Ming-Jie Jiang, and Ke Jiang from the Sun Yat-sen University Cancer Center and was published in 2024 in the journal Precision Clinical Medicine. The study received support from multiple projects, including the National Natural Science Foundation of China and the Guangdong Basic and Applied Basic Research Foundation.

Research Process

1. Extraction and Characterization of Exosomes

The researchers first extracted exosomes from highly metastatic NPC cells (S18) and low-metastatic NPC cells (S26). Exosomes were isolated using differential centrifugation and characterized using transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and western blotting. The results showed that the extracted exosomes exhibited typical exosomal characteristics, including a diameter of 30-150 nm and expression of exosomal markers such as ALIX, CD9, and CD63.

2. Impact of Exosomes on Cell Migration and Invasion

To investigate the effect of exosomes on the metastatic potential of NPC cells, the researchers treated CNE-2 cells (an NPC cell line) with exosomes derived from highly metastatic S18 cells and low-metastatic S26 cells. Transwell migration and invasion assays revealed that exosomes from S18 cells significantly enhanced the migration and invasion abilities of CNE-2 cells. Further experiments showed that the exosome secretion inhibitor GW4869 blocked this promoting effect, while the addition of exosomes restored the enhancement of cell migration and invasion.

3. miRNA Sequencing and Functional Validation

To explore which molecules in exosomes mediate this metastatic promotion, the researchers performed miRNA sequencing on exosomes derived from S18 and S26 cells. The results showed that miR-30a-5p was significantly upregulated in exosomes from highly metastatic S18 cells. qRT-PCR validation confirmed that miR-30a-5p was highly expressed not only in S18 cells but also in CNE-2 and S26 cells treated with S18 exosomes. Further functional experiments demonstrated that overexpression of miR-30a-5p significantly enhanced the migration and invasion abilities of NPC cells, while its inhibitor suppressed these abilities.

4. In Vivo Validation of miR-30a-5p

To validate the role of miR-30a-5p in vivo, the researchers constructed CNE-2 cells overexpressing miR-30a-5p and injected them into nude mice via the tail vein. Six weeks later, dissection of the mouse lungs revealed a significant increase in the number of metastatic nodules and lung weight in the miR-30a-5p overexpression group. Additionally, CNE-2 cells treated with exosomes overexpressing miR-30a-5p also exhibited stronger metastatic potential in vivo.

5. Target Gene and Mechanism of miR-30a-5p

Using multiple miRNA target prediction algorithms, the researchers identified desmoglein 2 (DSG2) as a potential target of miR-30a-5p. Dual-luciferase reporter assays confirmed that miR-30a-5p inhibits DSG2 expression by binding to its 3’ untranslated region (3’UTR). Further experiments showed that overexpression of DSG2 suppressed the migration and invasion abilities of NPC cells, while miR-30a-5p promoted tumor metastasis by inhibiting DSG2 expression and activating the Wnt/β-catenin signaling pathway.

6. Clinical Sample Analysis and Prognostic Prediction

The researchers collected plasma samples from 119 NPC patients and measured the expression level of miR-30a-5p in plasma exosomes using qRT-PCR. The results showed that high expression of miR-30a-5p was significantly associated with overall survival (OS), progression-free survival (PFS), distant metastasis-free survival (DMFS), and local recurrence-free survival (LRFS) in patients. Furthermore, the expression level of miR-30a-5p was negatively correlated with DSG2 expression in tumor tissues, further supporting the mechanism by which miR-30a-5p promotes tumor metastasis by inhibiting DSG2.

Research Conclusions

This study revealed that highly metastatic NPC cells enhance the metastatic potential of low-metastatic cells by transmitting miR-30a-5p via exosomes. miR-30a-5p promotes tumor metastasis by targeting and inhibiting DSG2 expression, thereby activating the Wnt/β-catenin signaling pathway. Additionally, the level of miR-30a-5p in plasma exosomes can serve as a reliable prognostic marker for NPC patients. This discovery not only provides new insights into the mechanisms of NPC metastasis but also offers a theoretical basis for developing exosome-based liquid biopsy and targeted therapeutic strategies.

Research Highlights

  1. Innovative Discovery: First to reveal that highly metastatic NPC cells enhance the metastatic potential of low-metastatic cells by transmitting miR-30a-5p via exosomes.
  2. Mechanistic Depth: Detailed the molecular mechanism by which miR-30a-5p promotes tumor metastasis by inhibiting DSG2 and activating the Wnt signaling pathway.
  3. Clinical Application: The level of miR-30a-5p in plasma exosomes can serve as a prognostic biomarker for NPC patients, providing a new direction for liquid biopsy.
  4. Interdisciplinary Approach: Combined multidisciplinary research methods from molecular biology, cell biology, and clinical medicine, offering a new paradigm for tumor metastasis research.

Research Significance

This study not only deepens the understanding of NPC metastasis mechanisms but also provides important theoretical foundations for developing new therapeutic strategies and prognostic markers. The discovery that highly metastatic cancer cells can influence the behavior of low-metastatic cells through exosome-mediated intercellular communication offers new targets for future cancer treatments. Additionally, exosome-based liquid biopsy technology holds promise for widespread clinical application, helping doctors predict patient prognosis earlier and develop personalized treatment plans.