Chronic stress not only induced depressive behaviors but also accelerated ovarian cancer growth in mice by downregulating HDC expression in tumors, whereas exogenous HIS treatment alleviated depressive symptoms, suppressed cancer growth, and countered the decreased levels of HIS and increased levels of IL-6, IL-17A, NE, COR, and 5-HT induced by CUMS. The gene discussed is IL17A; the disease is cancer.