Cancer stem cells (CSCs) are a subpopulation of cells within tumors that possess stem-like properties, including self-renewal and the ability to differentiate into various cancer cell types. These CSCs are believed to play a significant role in tumor initiation, progression, metastasis, treatment resistance, and recurrence. Targeting CSCs is therefore a crucial strategy for achieving durable cancer remission.

Emerging research suggests that Thymoquinone (TQ), a natural compound from Nigella sativa, may have a significant impact on cancer stem cells. Preclinical studies have indicated that TQ can affect CSC populations in various cancer types, including breast cancer. These studies have shown that TQ can reduce the proportion of CSCs, often identified by markers like CD44+/CD24− in breast cancer cells.

The mechanisms by which TQ might target CSCs are still being explored but likely involve the modulation of pathways critical for stem cell function. CSCs often rely on specific signaling pathways, such as Wnt, Notch, and Hedgehog, for their self-renewal and survival. TQ's known ability to interfere with pathways like Wnt/β-catenin and PI3K/Akt may contribute to its effects on CSCs.

Furthermore, the resistance of CSCs to conventional chemotherapy is a major challenge in cancer treatment. TQ's potential to overcome this resistance, as seen in its synergistic effects with chemotherapy, could also extend to CSCs. By making CSCs more susceptible to treatment or by directly targeting their survival mechanisms, TQ could play a role in preventing tumor recurrence.

While the evidence is still primarily from preclinical research, the prospect of Thymoquinone targeting cancer stem cells offers a promising new avenue for cancer therapy. By addressing the root of tumor recurrence and resistance, TQ could contribute to more effective and long-lasting cancer treatment outcomes. Further research is essential to elucidate these mechanisms and translate these findings into clinical applications.