Chemosensitivity Of Breast Cancer Cells Research Articles

Mir-451a-5p Modulates Breast Cancer Cell Apoptosis, Migration, and Chemosensitivity to Carboplatin through the PTEN Pathway

Background: MicroRNAs (miRNAs) can play essential roles in the modulation of cancer cell growth, survival, and resistance to chemotherapy. Thus, we hypothesized that restoration of miR-451a-5p (a tumor suppressor) might affect sensitivity to chemotherapeutics in breast cancer cells. Methods: For this purpose, malignant breast cancer cells (MDA-MB-231) were transfected with miR-451a-5p mimic and exposed with carboplatin. Then, the apoptotic rate was evaluated by flow cytometry and DAPI staining (apoptosis), q-RT-PCR (expression levels of caspase-3, caspase-8, MMP9, ROCK, vimentin, c-Myc genes). Moreover, the proliferation and migration of cancer cells were assessed by MTT (cell viability) and wound healing assay. The western blot assay was used for protein expression of PTEN, AKT, and P-AKT. Results: Our findings demonstrated that a combination of miR-451a-5p restoration with carboplatin administration could additionally induce apoptosis, repress the proliferation and migration, and also increase PTEN protein expression with no significant alteration on the AKT/P-AKT protein expressions in the breast cancer cells. The present data was analyzed using GraphPad Prism 6 software by non-parametric one-way ANOVA and t-test. Conclusion: In conclusion, it seems that overexpression of miR-451a can enhance the chemosensitivity of breast cancer cells to carboplatin therapy. Thus, it may shed new light on miR-451a management of breast cancer chemoresistance and may be a beneficial strategy for future cancer therapy. However, further studies, particularly in other signaling pathways, should be required.

Treatment with eFT-508 increases chemosensitivity in breast cancer cells by modulating the tumor microenvironment

BackgroundPatients with triple-negative breast cancer (TNBC) are better responders to neoadjuvant chemotherapy; however, they are poor in the durability of response with decreased overall and progression-free survival.MethodsGiven that significant improvements have been reported with PD-L1-PD-1 blockade in different cancers, we evaluated the in vitro and in vivo effectiveness of Tomivosertib (eFT-508), an anthracycline, adriamycin, and MNK1/2 inhibitor, which has been previously shown to inhibit translation of PD-L1 in mice model of liver cancer, alone or in combination using BC cell lines and an orthotopic xenograft mice model using the TNBC cell line MDA-MB-231.ResultsWithin the context of The Cancer Genome Atlas (TCGA) dataset, expression of CD274 mRNA, which encodes programmed death-ligand 1 (PD-L1), was found to be significantly overexpressed in TNBC patients compared to patients with HER2 + or luminal breast cancer (BC). Even within TNBC sub-types, CD274 expression was significantly higher in the immune modulatory subtype (TNBC-IM).BC cells exhibited high IC50 = 0.85 ± 0.07 nM with Adriamycin and significantly lower IC50 = 0.23 ± 0.04 nM with eFT-508 (P < 0.01). Combination treatment showed in vitro synergism on chemosensitivity. Combination therapy also exhibited a synergistic effect on inhibition of tumor growth and lung colonization in vivo. Mass cytometry-based evaluation of the tumor microenvironment revealed significant attenuation of both PD-L1 and PD-L2 following mono- or combination therapy with eFT-508.ConclusionsTreatment with eFT-508 restored effector and cytotoxic function of tumor-infiltrating CD8 + T cells in mice. The remarkable efficacy observed both in vitro and in vivo, and clinical synergism with adriamycin, highlights the potential of eFT-508 as an alternative, yet more efficacious, therapeutic option for patients with TNBC.

Ambra1 regulates apoptosis and chemosensitivity in breast cancer cells through the Akt-FoxO1-Bim pathway.

The sensitivity of cells to chemotherapeutic agents has a major effect on disease outcome in breast cancer patients. Unfortunately, there are numerous factors involved in the regulation of chemosensitivity, and the mechanisms need to be further investigated. Autophagy/Beclin 1 regulator 1 (Ambra1) is a key protein in the crosstalk between autophagy and apoptosis. It controls the switch between these two processes, which determines whether cells survive or die. Induction of apoptosis is the primary mechanism by which most chemotherapeutic drugs eliminate cancer cells. Recently, Ambra1 has been shown to modulate paclitaxel-induced apoptosis in breast cancer cells via the Bim/mitochondrial pathway, thereby modifying the sensitivity of cells to paclitaxel. However, how Ambra1 regulates Bim expression remains unclear. Here, we further confirmed that Bim plays an indispensable role in Ambra1's regulation of apoptosis and chemosensitivity in breast cancer cells. Furthermore, Ambra1 was found to regulate Bim expression at the transcriptional level through the Akt-FoxO1 pathway. Therefore, we propose a novel pathway, Ambra1-Akt-FoxO1-Bim, which regulates apoptosis and chemosensitivity in breast cancer cells. Thus, Ambra1 may represent a potential target for breast cancer treatment.

REXO4 acts as a biomarker and promotes hepatocellular carcinoma progression.

Hepatocellular carcinoma (HCC) is a leading cause of global cancer-related mortality and the most common form of liver cancer. REXO4 (RNA exonuclease 4 homolog) downregulation has previously been linked to enhanced chemosensitivity in breast cancer cells. The present study sought to comprehensively clarify the functional role of REXO4 in HCC. REXO4 expression levels in HCC tumor tissues and control tissue samples were established by analyzing data from the Gene Expression Omnibus (GEO) database. The expression of REXO4 was then knocked down in HCC cell lines to explore its functional role in these cells, while a gene set enrichment analysis (GSEA) approach was used to assess the functional regulator network associated with REXO4, and the Cell type Identification By Estimating Relative Subsets Of RNA Transcripts (CIBERSORT) algorithm was used to determine the relationship between this gene and immune cell infiltration of tumor tissues. The relationship between REXO4 and metabolic pathway was analyzed by oil red O staining. Cell Counting Kit-8 assays, colony formation, wound-healing assay, and a nude mouse subcutaneous tumor model were used to evaluate the function of REXO4 in HCC. REXO4 was highly upregulated in HCC tumors and cell lines, and was an effective predictor of HCC patient prognosis. The results indicated that the knockdown of REXO4 inhibited the proliferation and progression of HCC in vitro and in vivo. GSEA approaches also revealed REXO4 to be associated with tumor progression. Furthermore, REXO4 was associated with the degree of increase of intratumoral immune cell infiltration in HCC tissues and cells, and this gene was also linked with altered lipid metabolism in HCC cells. In summary, these analyses revealed REXO4 to be upregulated in HCC and to be associated with poor patient prognosis. In addition, this gene was closely linked to key cancer hallmark pathways and was revealed to play an important role in the susceptibility of liver tumors to immune cell infiltration and activation. Thus, targeting REXO4 may be a promising approach to treating patients with HCC in the near future.

Rhinacanthin-C enhances chemosensitivity of breast cancer cells via the downregulation of P-glycoprotein through inhibition of Akt/NF-kappa B signaling pathway

Introduction: High expression of P-glycoprotein (P-gp) has been linked to multidrug resistance (MDR) and chemotherapeutic failure. Previously, we demonstrated that rhinacanthin-C, a naphthoquinone from Rhinacanthus nasutus, was able to enhance the cytotoxicity of doxorubicin against breast cancer MCF-7 cells via direct P-gp inhibition. In this study, we looked at its effect on P-gp downregulation and the mechanism involved in the resistance of MCF-7 cells to doxorubicin. Methods: Doxorubicin-resistant MCF-7 (MCF-7/DOX) cells were exposed to rhinacanthin-C for 24-48 hours prior to the assessment of their chemosensitivity via MTT assay, P-gp activity via calcein-AM uptake assay, P-gp expression, and signaling via qRT-PCR and western blot analyses. Results: Pretreatment with 1 µM of rhinacanthin-C for 48 hours significantly enhanced cytotoxicity of doxorubicin, as well as camptothecin and etoposide, to MCF-7/DOX cells. In the rhinacanthin-C-treated cells, reduction of MDR1 mRNA and P-gp levels and increased intracellular calcein were observed. Moreover, phosphorylation of Akt, NF-ᴋB and IκB-α, along with YB-1 expression, significantly decreased after 24-hour treatment with rhinacanthin-C. In contrast, the naphthoquinone had no effect on expression levels of ERK1/2 and phosphorylated ERK1/2 under similar conditions. Conclusion: Rhinacanthin-C, at a non-cytotoxic concentration (1 µM), could downregulate P-gp expression in MCF-7/DOX cells via the inhibition of the Akt/NF-ᴋB signaling pathway and YB-1 expression. Long-term exposure to this natural naphthoquinone may increase the chemosensitivity of cancer cells with MDR phenotype.

Targeting PKM2 promotes chemosensitivity of breast cancer cells in vitro and in vivo.

Pyruvate kinase M2 (PKM2) was overexpressed in many cancers, and high PKM2 expression was related with poor prognosis and chemoresistance. We investigated the expression of PKM2 in breast cancer and analyzed the relation of PKM2 expression with chemotherapy resistance to the neoadjuvant chemotherapy (NAC). We also investigated whether PKM2 could reverse chemoresistance in breast cancer cells in vitro and in vivo. Immunohistochemistry (IHC) was performed in 130 surgical resected breast cancer tissues. 78 core needle biopsies were collected from breast cancer patients before neoadjuvant chemotherapy. The relation of PKM2 expression and multi-drug resistance to NAC was compared. The effect of PKM2 silencing or overexpression on Doxorubicin (DOX) sensitivity in the MCF-7 cells in vitro and in vivo was compared. PKM2 was intensively expressed in breast cancer tissues compared to adjacent normal tissues. In addition, high expression of PKM2 was associated with poor prognosis in breast cancer patients. The NAC patients with high PKM2 expression had short survival. PKM2 was an independent prognostic predictor for surgical resected breast cancer and NAC patients. High PKM2 expression was correlated with neoadjuvant treatment resistance. High PKM2 expression significantly distinguished chemoresistant patients from chemosensitive patients. In vitro and in vivo knockdown of PKM2 expression decreases the resistance to DOX in breast cancer cells in vitro and tumors in vivo. PKM2 expression was associated with chemoresistance of breast cancers, and could be used to predict the chemosensitivity. Furthermore, targeting PKM2 could reverse chemoresistance, which provides an effective treatment methods for patients with breast cancer.

MicroRNA-424-5p enhances chemosensitivity of breast cancer cells to Taxol and regulates cell cycle, apoptosis, and proliferation.

Combination therapy has been considered as a potential method to overcome the BC chemoresistance. MicroRNAs (miRs) have been suggested as a therapeutic factor in the combination therapy of BC. This project aimed at examining the possible activity and molecular function of miR-424-5p and Taxol combination in the human BC cell line. MDA-MB-231 cells were treated with miR-424-5p mimics and Taxol, in a combined manner or separately. We used the MTT test for assessing the cell proliferation. In addition, flow-cytometry was used for evaluating apoptosis and cell-cycle. Expression levels of underlying molecular factors of miR-424-5p were assessed using western-blotting and qRT-PCR. The obtained results demonstrated that miR-424-5p repressed BC cell proliferation and sensitized these cells to Taxol treatment through the induction of apoptosis. Further investigations showed that miR-424-5p might increase BC chemosensitivity through the regulation of apoptosis-related factors including P53, Caspase-3, Bcl-2, and Bax as well as the proliferation-related gene c-Myc. Moreover, miR-424-5p restoration in combination with Taxol treatment decreased the colony formation by regulating Oct-4 and led to G2 arrest via modulating Cdk-2 expression. Western-blotting demonstrated that miR-424-5p may perform its anti-chemoresistance role by regulating the PD-L1 expression and controlling PTEN/PI3K/AKT/mTOR. Overall, the upregulation of miR-424-5p was indicated to upregulate the sensitivity of BC cells to treatment with Taxol. MiR-424-5p might regulate the chemosensitivity of the BC cell line by modulating PD-L1 and controlling the PTEN/mTOR axis. Therefore, the combination of miR-424-5p with Taxol would represent a novel procedure to treat against BC.

MEDAG enhances breast cancer progression and reduces epirubicin sensitivity through the AKT/AMPK/mTOR pathway

Breast cancer (BC) is the most common malignancy among women. Mesenteric estrogen-dependent adipogenesis gene (MEDAG) was first reported as a novel adipogenic gene, and its involvement and mechanism in visceral adiposity were analyzed. However, the role of MEDAG in BC is unclear. The biological roles and corresponding mechanisms were investigated in vitro and in vivo. We found that MEDAG was highly expressed in BC samples and that a high MEDAG expression was correlated with clinicopathological characteristics and poor survival in BC patients. MEDAG knockdown inhibited cell proliferation, invasion, and migration; triggered epithelial-to-mesenchymal transition (EMT); and enhanced epirubicin sensitivity in vitro. The opposite results were observed in MEDAG-overexpressing cells. The inhibition of MEDAG suppressed tumor growth and metastasis in vivo. Mechanistically, MEDAG knockdown led to decreased phosphorylation levels of AKT, increased levels of p-AMPK, and reduced levels of p-mTOR, while the overexpression of MEDAG had the opposite effects. Moreover, the activation of p-AKT and inhibition of p-AMPK restored the effect of MEDAG on EMT and chemosensitivity in BC cell lines, indicating that MEDAG functions as an oncogene by regulating the AKT/AMPK/mTOR pathway. MEDAG regulates BC progression and EMT via the AKT/AMPK/mTOR pathway and reduces chemosensitivity in BC cells. Therefore, MEDAG is a promising target for BC.

The apple dihydrochalcone phloretin suppresses growth and improves chemosensitivity of breast cancer cells via inhibition of cytoprotective autophagy.

The inhibitory effect and mechanism of the apple dihydrochalcone, phloretin, on breast cancer cell growth were evaluated in in vitro conditions simulating complete nutrition and glucose-restriction, respectively. In two breast cancer cell lines with different histological backgrounds, phloretin consistently exhibited much stronger activity against cell growth in glucose-limiting than in full media. RNA-seq analysis showed that key autophagy-related genes were downregulated upon phloretin treatment in both estrogen-receptor-positive MCF7 and triple-negative MDA-MB-231 cells. Immunoblotting verified significantly decreased expression of LC3B-II by phloretin in low-glucose and glucose-free media, but not in full medium. Together with the use of two pharmacological autophagy inhibitors, chloroquine and 3-methyladenine, and confocal microscopy of breast cancer cell lines transfected with GFP-LC3B, phloretin demonstrated a strong capability to suppress autophagic flux, which was likely mediated through downregulation of mTOR/ULK1 signaling, whereas the expression of canonical autophagy regulators ATG5 and ATG7 was not significantly affected. Phloretin also reversed tamoxifen- and doxorubicin-induced cytoprotective autophagy in the breast cancer cell lines, and this was manifested in its synergistic growth inhibitory effect with these chemotherapeutic agents. Furthermore, it was able to restore or enhance the chemosensitivity of a tamoxifen-resistant cell line. Taken together, our study has, for the first time, revealed that phloretin could effectively suppress glucose-starvation- and chemotherapeutic-induced cytoprotective autophagy in breast cancer cell lines likely through downregulation of mTOR/ULK1 signaling.

Calcium-Binding Protein S100P Promotes Tumor Progression but Enhances Chemosensitivity in Breast Cancer.

BackgroundChemoresistance remains one of the obstacles to overcome in the treatment of breast cancer. S100 calcium-binding protein P (S100P) has been observed to be overexpressed in several cancers and has been associated with drug resistance, metastasis, and prognosis. However, the role of S100P in chemoresistance in breast cancer has not been thoroughly determined.MethodsImmunohistochemistry was used to evaluate the expression level of S100P protein in 22 pairs (pre-chemo and post-chemo) of breast cancer tissue from patients who underwent neoadjuvant chemotherapy. The influence of S100P on the biological behavior and chemosensitivity of breast cancer cells was then investigated.ResultsThe protein level of S100P in breast cancer tissue was significantly higher than in benign fibroadenoma (p < 0.001). The S100P expression level was shown to be decreased by 46.55% after neoadjuvant chemotherapy (p = 0.015). Subgroup analysis revealed that S100P reduction (57.58%) was mainly observed in the HER2+ tumors (p = 0.027). Our in vitro experiments showed that the knockdown of S100P suppressed the proliferation, adhesion, migrative and invasive abilities of T47D and SK-BR-3 breast cancer cells. We further demonstrated that this knockdown increased the chemoresistance to paclitaxel and cisplatin in SK-BR-3 cells. We found S100P exerted its function by upregulating NF-κB, CCND1 and Vimentin, but downregulating E-cadherin.ConclusionS100P promotes the aggressive properties of breast cancer cells and may be considered as a promising therapeutic target. Moreover, S100P can be used to predict the therapeutic effect of chemotherapy in HER2+ breast cancer patients.

Tanshinone II A improves the chemosensitivity of breast cancer cells to doxorubicin by inhibiting β-catenin nuclear translocation.

Numerous evidence linkaberrant nuclear β-catenin accumulation to the development of breast cancer resistance, therefore, targeted inhibition of β-catenin nuclear translocation may effectively improve the chemosensitivity of breast cancer. Doxorubicin (Dox) is the most commonly used chemotherapeutic drug for breast cancer. Here, we determined that tanshinone II A (Tan II A) could improve the sensitivity of Dox-resistant breast cancer MCF-7/dox cells to Dox, and evaluated whether the sensitization effect of Tan II A on Dox was targeted to inhibit β-catenin nuclear translocation. The results showed that Tan II A not only significantly inhibited the nuclear translocation of β-catenin in MCF-7/dox cells treated by Dox but also inhibited the nuclear translocation of β-catenin in MCF-7 cells treated by Dox to a certain degree. Furthermore, when the above two cells treated by Dox combined with Tan II A were intervened with β-catenin agonist WAY-262611, with the re-nuclear translocation of β-catenin in the cells, the sensitization effect of Tan II A on Dox was greatly reduced. These results indicated that Tan II A could improve the chemosensitivity of breast cancer cells to Dox by inhibiting β-catenin nuclear translocation. Therefore, Tan II A could be used as a potential chemosensitizer in combination with Dox for breast cancer chemotherapy.

MiR-204/COX5A axis contributes to invasion and chemotherapy resistance in estrogen receptor-positive breast cancers.

Breast cancer is the most common cancer among women worldwide, with 70% being estrogen receptor-positive (ER+). Although ER-targeted treatment is effective in treating ER+breast cancer, chemoresistance and metastasis still prevail. Outcome-predictable biomarkers can help improve patient prognosis. Through the analysis of the Array Express database, The Cancer Genome Atlas-Breast Cancer datasets, and breast tumor tissue array results, we found that cytochrome c oxidase subunit 5a (COX5A) was related to poor prognosis of ER+breast cancer. Further studies revealed that COX5A was positively associated with metastasis and chemoresistance in ER+breast cancer. In vitro experiments showed that knockdown of COX5A was accompanied by a decrease in ERα expression, cell cycle arrest, and epithelial-mesenchymal transition blockade, resulting in an inhibition of proliferation and invasion. Knockdown of COX5A enhanced the chemosensitivity of breast cancer cells by decreasing adenosine triphosphate and increasing reactive oxygen species levels. We report that miR-204 can target and inhibit the expression of COX5A, thus, reversing the functions of COX5A in ER+breast cancer cells. We found that COX5A may serve as a prognostic biomarker in ER+breast cancer.

Suppression of Long Non-Coding RNA Metastasis-Associated Lung Adenocarcinoma Transcript 1 (MALAT1) Potentiates Cell Apoptosis and Drug Sensitivity to Taxanes and Adriamycin in Breast Cancer.

BackgroundThe long non-coding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is expressed highly in various types of tumors. Moreover, the tumor-initiating role of MALAT1 has been probed in the context of breast cancer. This study was set to investigate the regulatory role of MALAT1 on the chemosensitivity of breast cancer cells to taxanes (Tax) and adriamycin (Adr).Material/MethodsFollowing the measurement of MALAT1 expression in patients with breast cancer by means of qRT-PCR, the connection between the MALAT1 expression pattern and the prognosis of breast cancer patients as well as the molecular typing of breast cancer patients was analyzed using Kaplan-Meier survival analysis and receiver operating characteristic (ROC) curves. Next, the analysis between the expression of MALAT1 and the clinical symptoms of breast cancer patients was carried out. Subsequently, we generated taxane-resistant MCF-7 cells (MCF-7/Tax) and purchased Adr-resistant MCF-7 cells (MCF-7/Adr). Finally, the proliferation, apoptosis and drug resistance of resistant and parental cells were evaluated after transfection of silencing MALAT1 into these cells.ResultsMALAT1 was highly expressed in the breast cancer tissues. Moreover, patients with relative overexpression of MALAT1 had worse prognosis. MALAT1 expression was remarkably promoted in MCF-7/Tax and MCF-7/Adr cells, whose sensitivity to Tax and Adr was enhanced following MALAT1 knockdown.ConclusionsMALAT1 was elevated in breast cancer tissues and MCF-7-resistant cells, relative to corresponding controls and downregulation of MALAT1 inhibited the growth and chemoresistance of breast cancer cells to Tax and Adr.

Hypermethylation of lncRNA MEG3 impairs chemosensitivity of breast cancer cells.

BackgroundChemoresistance posed a barrier to successful treatment of breast cancer (BC), and lncRNA MEG3 has been documented to implicate in BC development. However, whether MEG3 methylation, which led to low MEG3 expression, was relevant to BC progression and chemoresistance remained uncertain.MethodsIn the aggregate, 374 pairs of tumor tissues and adjacent normal tissues were collected from pathologically confirmed BC patients, and four BC cell lines, including MDA‐MB‐231, Bcap‐37, MCF‐7, and SK‐BR‐3, were purchased. Moreover, methylation‐specific polymerase chain reaction (PCR) was adopted to evaluate the methylation status of BC tissues and cell lines, and chemo‐tolerance of BC cell lines was assessed by performing MTT assay. Concurrently, transwell assay and scratch assay were carried out to estimate the migratory and invasive capability of BC cell lines.ResultsMethylated MEG3, lowly expressed MEG3, large tumor size (≥2 cm), advanced TNM grade and lymphatic metastasis were potentially symbolic of poor prognosis among BC patients (P < .05). Besides, MDA‐MB‐231 cell line exhibited the strongest resistance against paclitaxel, adriamycin, and vinorelbine (P < .05), while MCF‐7 cell line seemed more sensitive against these drugs than any other BC cell line (P < .05). Furthermore, pcDNA3.1‐MEG3 and 5‐Aza‐dC markedly sensitized MDA‐MB‐231 and MCF‐7 cell lines against the drug treatments (P < .05). Simultaneously, proliferation and metastasis of the BC cell lines were slowed down under the force of pcDNA3.1‐MEG3 and 5‐Aza‐dC (P < .05).ConclusionPreventing methylation of MEG3 might matter in lessening BC chemoresistance, owing to its hindering proliferation and metastasis of BC cells.

Baicalin, a Potent Inhibitor of NF-κB Signaling Pathway, Enhances Chemosensitivity of Breast Cancer Cells to Docetaxel and Inhibits Tumor Growth and Metastasis Both In Vitro and In Vivo.

ObjectiveThe aim of this study is to investigate the anti-cancer activity and sensibilization of baicalin (BA) against breast cancer (BC) cells.MethodsThe anti-proliferation of BA in BC cell lines was evaluated by MTT and colony formation assays. Apoptotic induction of BA was measured by flow cytometry. Wound-healing and transwell assays were exploited to assess migrated and invasive inhibition of BA. Western-blot and immunofluorescence were used to study mechanisms of anti-migration and sensibilization of BA. Anti-tumor and anti-metastasis effects of BA were evaluated in subcutaneous and pulmonary metastasis mouse model of BC cells.ResultsBA significantly suppressed proliferation and induced apoptosis of BC cells in a concentration- and time-dependent manner. Additionally, BA induced cell apoptosis via the mitochondria-mediated pathway, as evidenced by cellular induction of reactive oxygen species and upregulated expression of the Bax/Bcl-2 ratio. The overall expression and nuclear translocation of NF-κB signaling pathway in BC cells were dramatically inhibited by treatment with BA. BA significantly suppressed abilities of migration and invasion in BC cells. Notably, BA sensitized BC cells to docetaxel (DXL) by suppressing the expression of survivin/Bcl-2. BA also retarded tumor growth and triggered apoptosis of tumor cells in a tumor mouse model of 4T1 cells. Furthermore, pulmonary metastasis of BC cells was distinctly suppressed by BA in a tumor mouse model of 4T1 cells.ConclusionBA effectively triggered apoptosis, inhibited metastasis, and enhanced chemosensitivity of BC, implying that BA might serve as a promising agent for the treatment of BC.

MiR-142-3p enhances chemosensitivity of breast cancer cells and inhibits autophagy by targeting HMGB1

MiR-142-3p has been reported to act as a tumor suppressor in breast cancer. However, the regulatory effect of miR-142-3p on drug resistance of breast cancer cells and its underlying mechanism remain unknown. Here, we found that miR-142-3p was significantly downregulated in the doxorubicin (DOX)-resistant MCF-7 cell line (MCF-7/DOX). MiR-142-3p overexpression increased DOX sensitivity and enhanced DOX-induced apoptosis in breast cancer cells. High-mobility group box 1 (HMGB1) is a direct functional target of miR-142-3p in breast cancer cells and miR-142-3p negatively regulated HMGB1 expression. Moreover, overexpression of HMGB1 dramatically reversed the promotion of apoptosis and inhibition of autophagy mediated by miR-142-3p up-regulation. In conclusion, miR-142-3p overexpression may inhibit autophagy and promote the drug sensitivity of breast cancer cells to DOX by targeting HMGB1. The miR-142-3p/HMGB1 axis might be a novel target to regulate the drug resistance of breast cancer patients.

XIAOPI formula promotes breast cancer chemosensitivity via inhibiting CXCL1/HMGB1-mediated autophagy

XIAOPI formula is a national approved drug prescribed to patients with high breast cancer risk. Previously we demonstrated that XIAOPI formula could inhibit breast cancer metastasis via suppressing CXCL1 expression, and postulated that “autophagy in cancer” might be one of its most core anti-cancer mechanisms. However, whether XIAOPI formula could be simultaneously applied with chemodrugs and their synergistic mechanisms are still remained unknown. In the present study, XIAOPI formula at non-cytotoxic doses could synergistically enhance the chemosensitivity of breast cancer cells MDA-MB-231 and MCF-7. We found that rapamycin-induced autophagy could reduce the chemosensitivity of breast cancer cells to XIAOPI formula, and the autophagy suppression and chemosensitizing activity of this formula was CXCL1-dependent. The evidence came from that XIAOPI formula was associated with a lower expression of CXCL1 combined with either rapamycin or taxol alone. Besides, the inhibitory effect of XIAOPI formula on the LC3-II and ABCG2 signals was weakened following CXCL1 over-expression, whereas P62 upregulation induced by XIAOPI formula was re-declined. A high throughput ­ qPCR (HT-qPCR) assay identified HMGB1 as the main autophagic target of XIAOPI formula in chemosensitizing breast cancer. and furhter validation suggested XIAOPI formula exerted chemosensitivity mainly via CXCL1/HMGB1 autophagic axis. Finally, we generated both mice and zebrafish xenotransplantation models bearing MDA-MB-231 breast cancer cells, and found that XIAOPI formula safely enhanced in vivo taxol chemosensitivity on breast cancer. Taken together, XIAOPI formula is a potential adjuvant drug via inhibiting CXCL1/HMGB1-mediated autophagy for breast cancer treatment with good safety.

Inhibition of PI3K pathway using BKM120 intensified the chemo-sensitivity of breast cancer cells to arsenic trioxide (ATO)

Although conventional therapeutic approaches have brought remarkable advantages for the treatment of breast cancer (BC), drug-resistance still remains as a leading cause of tumor recurrence in this malignancy. In the present study, we designed experiments to evaluate the therapeutic value of PI3K inhibition in combination with Arsenic trioxide (ATO) in MCF-7 cells. The results of our study manifested that BKM120 sensitized MCF-7 cells to the lower concentrations of ATO. The significant anti-cancer effect of PI3K inhibition became even more evident when we found that BKM120, either as a single agent or in combination with ATO, reduced clonogenic ability of anoikis-resistant stem-like MCF-7 cells. Our findings also showed that BKM120 augmented ATO-induced anti-proliferative effects through inducing G1 arrest and reducing the incorporation of BrdU into the synthesized DNA of drugs-treated cells, which was coupled with c-Myc-mediated suppression of hTERT expression. Moreover, we found that in the presence of PI3K inhibitor, ATO is able to more profoundly induce apoptosis in MCF-7 cells, as revealed by the increment in the percentage of haplodiploid sub-G1 cells and the externalization of phosphatidylserine. Real-time PCR analysis also revealed that probably down-regulation of survivin coupled with up-regulation of forkhead family transcription factors is responsible for the enhancive effect of drugs in this cell line. Conclusively, this study shed lights on the effect of PI3K inhibition in chemo-sensitivity of MCF-7 cells, disclosing that combination of BKM120 and ATO could be a promising therapeutic approach in BC.

Intracellular Delivery of siRNAs Targeting AKT and ERBB2 Genes Enhances Chemosensitization of Breast Cancer Cells in a Culture and Animal Model.

Pharmacotherapy as the mainstay in the management of breast cancer suffers from various drawbacks, including non-targeted biodistribution, narrow therapeutic and safety windows, and also resistance to treatment. Thus, alleviation of the constraints from the pharmacodynamic and pharmacokinetic profile of classical anti-cancer drugs could lead to improvements in efficacy and patient survival in malignancies. Moreover, modifications in the genetic pathophysiology of cancer via administration of small nucleic acids might pave the way towards higher response rates to chemotherapeutics. Inorganic pH-dependent carbonate apatite (CA) nanoparticles were utilized in this study to efficiently deliver various classes of therapeutics into cancer cells. Co-delivery of drugs and genetic materials was successfully attained through a carbonate apatite delivery device. On 4T1 cells, siRNAs against AKT and ERBB2 plus paclitaxel or docetaxel resulted in the largest increase in anti-cancer effects compared to CA/paclitaxel or CA/docetaxel. Therefore, these ingredients were selected for further in vivo investigations. Animals receiving injections of CA/paclitaxel or CA/docetaxel loaded with siRNAs against AKT and ERBB2 possessed significantly smaller tumors compared to CA/drug-treated mice. Interestingly, synergistic interactions in target protein knock down with combinations of CA/AKT/paclitaxel, CA/ERBB2/docetaxel were documented via western blotting.

Abstract 2565: Type I interferons enhance chemosensitivity of breast cancer by inhibiting DNA repair

Abstract Type I interferons (IFNs) are known to have antineoplastic effects against several tumors by stimulating anticancer immune response. In this study, we identified a novel function of type I IFNs in DNA repair, which enhanced chemosensitivity in breast cancer cells. We investigated that IFNα and IFNβ inhibited both non-homologous recombination and homologous recombination double strand breaks repair. Moreover, IFNs accelerated the release of DNA into the cytoplasm in response to DNA damaging agent, doxorubicin. In agreement, IFNs synergistically activated DNA damage-induced STING pathway and increased the production of chemokines, CCL5 and CXCL11. In agreement, IFNβ greatly increased the sensitivity of cells to doxorubicin-induced suppression of cell survival. This sensitizing effect of IFNβ was also supported by in vivo xenograft experiments. Thus, combination therapy with chemotherapeutic agents and IFNs may be effective against breast cancer, particularly in patients with defective in DNA damage response pathways. The downstream effectors that modulate the effect of IFNs should be investigated as predictive biomarker in the treatment of breast cancer. Citation Format: Na-Lee Ka, Ga Young Lim, Mi-Ock Lee. Type I interferons enhance chemosensitivity of breast cancer by inhibiting DNA repair [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2565.