Immunotherapy targeting program cell death protein 1 (PD-1) in addition to chemotherapy has improved the survival of triple-negative breast cancer (TNBC) patients. However, the development of resistance and toxicity remain significant problems. Using the translationally relevant 4T1 mouse model of TNBC, we report here that dietary administration of the phytochemical quercetin enhanced the antitumor action of Cyclophosphamide, a cytotoxic drug with significant immunogenic effects that is part of the combination chemotherapy used in TNBC. We observed that quercetin favorably modified the host fecal microbiome by enriching species such as Akkermansia muciniphilia, which has been shown to improve response to anti-PD-1 therapy. We also show that quercetin and, to a greater extent, Cyclophosphamide increased the systemic frequency of T cells and NK cells. In addition, Cyclophosphamide alone and in combination with quercetin reduced the frequency of Treg, which is consistent with an antitumor immune response. On the other hand, Cyclophosphamide did not significantly alter the host microbiome, suggesting complementarity between microbiome- and immune-mediated mechanisms in potentiating the antitumor action of Cyclophosphamide by quercetin. Overall, these results support the potential for microbiota-centered dietary intervention to overcome resistance to chemoimmunotherapy in TNBC.

Previously, we showed that oral application of the environmental pollutant dibenzo[a,l]pyrene (DB[a,l]P) induces oral tumors in mice. Thus, in the present investigation we examined the effect of alcohol on DB[a,l]P-induced DNA damage and immune regulation; we showed that alcohol (6.4% v/v in the diet, 35% of Calories) significantly enhanced the levels of (−)-anti-trans-DB[a,l]P-dA while decreased the levels of GSH in the mouse oral tissues. Analysis of RNA expression revealed that DB[a,l]P alone upregulates inflammatory genes while alcohol suppresses several markers of immune surveillance. Collectively, these results suggest that alcohol may enhance oral carcinogenesis induced by DB[a,l]P.

The 9-aminoacridine derivative, 2-({4-[4-(acridin-9-ylamino)phenylthio]phenyl}(2-hydroxyethyl)amino)ethan-1-ol (CK0402) was selected as a potential anticancer agent among a series of sulfur-containing 9-aminoacridine analogues. CK0402 is a topoisomerase 11 inhibitor and has been shown to exert impressive anticancer activities in both in vitro and in vivo assays. In the present study, we tested the effects of CK0402 in a panel of established human breast cancer cells with varying ER and HER2/neu status. The ER(-) and HER2-overexpressing SKBR-3 cells were the most sensitive cells tested in growth inhibition to CK0402 treatment, and the growth inhibition was in a time- and concentration-dependent manner. In addition, CK0402 also induced stronger G(2)/M arrest, apoptosis and autophagy in SKBR-3 cells than in ER(+) and HER2(-) MCF-7 cells. To the best of our knowledge, CK0402 is the first 9-aminoacridine analogue to induce autophagy. These findings suggest that CK0402 may be effective against the more aggressive and malignant ER(-) and HER2-overexpressing breast cancer. Towards this end, we further demonstrated that the combination of CK0402 and Herceptin exhibited synergistic/additive cytotoxic effects in SKBR-3 cells using the median-effect/combination-index isobologram methodology (CI value). Our results indicate that the combination of CK0402 and Herceptin may be a potential therapeutic option against the more aggressive ER(-) and HER2-overexpressing breast cancer.

As demonstrated by us earlier and by other researchers, a diet containing freeze-dried black raspberries (BRB) inhibits DNA damage and carcinogenesis in animal models. We tested the hypothesis that the inhibition of DNA damage by BRB is due, in part, to the enhancement of DNA repair capacity evaluated in the human HeLa cell extract system, an established in vitro system for the assessment of cellular DNA repair activity. The pre-treatment of intact HeLa cells with BRB extracts (BRBE) enhances the nucleotide excision repair (NER) of a bulky deoxyguanosine adduct derived from the polycyclic aromatic carcinogen benzo[a]pyrene (BP-dG) by ~24%. The NER activity of an oxidatively-derived non-bulky DNA lesion, guanidinohydantoin (Gh), is also enhanced by ~24%, while its base excision repair activity is enhanced by only ~6%. Western Blot experiments indicate that the expression of selected, NER factors is also increased by BRBE treatment by ~73% (XPA), ~55% (XPB), while its effects on XPD was modest (<14%). These results demonstrate that BRBE significantly enhances the NER yields of a bulky and a non-bulky DNA lesion, and that this effect is correlated with an enhancement of expression of the critically important NER factor XPA and the helicase XPB, but not the helicase XPD.