Combination of 3PO analog PFK15 and siPFKL efficiently suppresses the migration, colony formation ability, and PFK-1 activity of triple-negative breast cancers by reducing the glycolysis.

Among all the subtypes of breast cancer, triple-negative breast cancer (TNBC) has been associated with the worst prognosis. Recently, for many solid tumors (including breast cancer) metabolic reprogramming has appeared as a cancer cell hallmark, and the elevated glycolytic pathway has been linked to their aggressive phenotype. In the present study, we evaluated the prognostic and therapeutic relevance of PFKFB3 (6-phosphofructo-2- kinase/fructose-2,6-bisphosphatase) in TNBCs. Prognostic significance of PFKFB3 expression was evaluated in overall breast cancers as well as in TNBCs. PFKFB3 inhibitor (3PO potent analogue i.e., PFK15) cytotoxicity in TNBC cell lines (MDA-MB-231 and MDA-MB-468) was analyzed using an MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Cancer cell physiological characteristics like clonogenicity and migration were also investigated after PFK15 treatment. As fructose-2,6-bisphosphate (F-2,6-BP), has been associated with increased PFK-1 activity, the effect of PFKFB3 inhibition by PFK15 was investigated on two major isoforms of phosphofructokinase-1 (PFK-1) in breast cancer, that is, phosphofructokinase-platelet type (PFKP) and phosphofructokinase-liver type (PFKL) (relevant to breast cancer). For PFKL inhibition, the siRNA approach was used. PFKFB3 expression was significantly correlated with inferior overall survival in breast cancer patients including TNBCs. PFK15 treatment in TNBC cells (i.e., MDA-MB-231 and MDA-MB-468) resulted in a decreased PFKP expression, thereby leading to reduced colony formation ability, migration rate, and extracellular lactate levels. However, to our surprise PFK15 treatment in both TNBC cells also resulted in elevated PFKL levels. Our results demonstrated that the combinatorial inhibition of PFK15 with siPFKL was more effective in TNBC cells, as it led to a decrease in colony formation ability, migration rate, extracellular lactate levels, and PFK-1 activity when compared with individual treatments. Using bona fide PFKFB3 inhibitor, that is, AZ67, we further show that AZ67 treatment to TNBC cells has no effect either on the expression of PFKP and PFKL, or on the lactate production. In summary, our present in vitro study demonstrated that 3PO derived PFK15 mechanism of action is totally different from AZ67 in TNBC cells. However, we advocate that the PFK15-mediated inhibition (along with PFKL) on the TNBCs migration, colony formation, and PFK-1 activity can be further explored for the therapeutic advantage of TNBC patients.

Quercetin Impairs HuR-Driven Progression and Migration of Triple Negative Breast Cancer (TNBC) Cells.

In the present study, we have explored the prognostic value of HuR gene as well as protein in breast cancers. Furthermore, we have also investigated the HuR therapeutic relevance in TNBCs, which is an aggressive breast cancer subtype. Using an online meta-analysis tool, we found that HuR protein overexpression positively correlates with reduced overall survival of TNBC patients (p = 0.028). Furthermore, we demonstrated that the TNBC breast cancer cell lines i.e., MDA-MB-231 and MDA-MB-468 are good model systems to study HuR protein, as they both exhibit a significant amount of cytoplasmic HuR (active form). Quercetin treatment significantly inhibited the cytoplasmic HuR in both TNBC cell lines. By using specific HuR siRNA, we established that quercetin-mediated inhibition of adhesion and migration of TNBC cells is dependent on HuR. Upon analyzing adhesion proteins i.e., ß-catenin and CD44, we found that quercetin mediated effect on TNBC adhesion and migration was through the HuR-ß-catenin axis and CD44, independently. Overall, the present results demonstrate that elevated HuR levels are associated with TNBC progression and relapse, and the ability of quercetin to inhibit cytoplasmic HuR protein provides a rationale for using it as an anticancer agent for the treatment of aggressive TNBCs.Supplemental data for this article is available online at at 10.1080/01635581.2021.1952628.

Dihydrotanshinone-I modulates Epithelial Mesenchymal Transition (EMT) Thereby Impairing Migration and Clonogenicity of Triple Negative Breast Cancer Cells.

BACKGROUND: Salvia miltiorrhiza Bunge (Danshen), has been used for its therapeutic value in Traditional Chinese Medicine (TCM), for almost a thousand years. Dihydrotanshinone-I (DHTS) is a lipophilic compound isolated from the plant Salvia miltiorrhiza that has been shown to induce anti-proliferative and apoptotic effects on breast cancer cells. In the present study, we investigated the anti-migratory effect of DHTS on TNBC cell lines by studying the Epithelial Mesenchymal Transition (EMT) changes. METHODS: IC50 values for DHTS in TNBC breast cancer cells were either discovered by literature search or by performing MTT assay. DHTS effect on EMT markers (viz. CD44, E-cadherin, Vimentin, N-cadherin, and active ß-catenin) was studied using western blotting. Association between EMT and migration was further carried out in DHTS treated TNBC cells by wound healing assay. Cancer stemness and proliferation potential were further accessed using colony formation assay. RESULTS: MTT assay revealed IC50 of MDA-MB-468 cells at 2 µM for 24 h. Subsequently, DHTS treatment in TNBC cell lines (MDA-MB-468 and MDA-MB-231) led to decrease in mesenchymal markers i.e. vimentin, N-cadherin and, active ß-catenin. DHTS treated MDA-MB-468 cells showed a decrease in adhesion protein CD44 and an increase in epithelial protein E-cadherin. Additionally, a decrease in EMT potential was positively associated with the inhibition of migration and clonogenic potential in DHTS treated TNBC cells. CONCLUSION: In this study, we have demonstrated for the first time that DHTS has the potential to inhibit the migration and clonogenicity of highly aggressive TNBC cells by obstructing Epithelial to Mesenchymal Transition.