Progress: Targeted Therapy, Immunotherapy, and New Chemotherapy Strategies in Advanced Triple-Negative Breast Cancer

Detection of lineage-reprogramming efficiency of tumor cells in a 3D-printed liver-on-a-chip model

Background: The liver metastasis accompanied with the loss of liver function is one of the most common complications in patients with triple-negative breast cancers (TNBC). Lineage reprogramming, as a technique direct inducing the functional cell types from one lineage to another lineage without passing through an intermediate pluripotent stage, is promising in changing cell fates and overcoming the limitations of primary cells. However, most reprogramming techniques are derived from human fibroblasts, and whether cancer cells can be reversed into hepatocytes remains elusive. Methods: Herein, we simplify preparation of reprogramming reagents by expressing six transcriptional factors (HNF4A, FOXA2, FOXA3, ATF5, PROX1, and HNF1) from two lentiviral vectors, each expressing three factors. Then the virus was transduced into MDA-MB-231 cells to generated human induced hepatocyte-like cells (hiHeps) and single-cell sequencing was used to analyze the fate for the cells after reprogramming. Furthermore, we constructed a Liver-on-a-chip (LOC) model by bioprinting the Gelatin Methacryloyl hydrogel loaded with hepatocyte extracellular vesicles (GelMA-EV) bioink onto the microfluidic chip to assess the metastasis behavior of the reprogrammed TNBC cells under the 3D liver microenvironment in vitro. Results: The combination of the genes HNF4A, FOXA2, FOXA3, ATF5, PROX1 and HNF1A could reprogram MDA-MB-231 tumor cells into human-induced hepatocytes (hiHeps), limiting metastasis of these cells. Single-cell sequencing analysis showed that the oncogenes were significantly inhibited while the liver-specific genes were activated after lineage reprogramming. Finally, the constructed LOC model showed that the hepatic phenotypes of the reprogrammed cells could be observed, and the metastasis of embedded cancer cells could be inhibited under the liver microenvironment. Conclusion: Our findings demonstrate that reprogramming could be a promising method to produce hepatocytes and treat TNBC liver metastasis. And the LOC model could intimate the 3D liver microenvironment and assess the behavior of the reprogrammed TNBC cells.

Molecular Classification, Treatment, and Genetic Biomarkers in Triple-Negative Breast Cancer: A Review

Breast cancer is the most common malignancy and the second most common cause of cancer-related mortality in women. Triple-negative breast cancers do not express estrogen receptors, progesterone receptors, or human epidermal growth factor receptor 2 and have a higher recurrence rate, greater metastatic potential, and lower overall survival rate than those of other breast cancers. Treatment of triple-negative breast cancer is challenging; molecular-targeted therapies are largely ineffective and there is no standard treatment. In this review, we evaluate current attempts to classify triple-negative breast cancers based on their molecular features. We also describe promising treatment methods with different advantages and discuss genetic biomarkers and other prediction tools. Accurate molecular classification of triple-negative breast cancers is critical for patient risk categorization, treatment decisions, and surveillance. This review offers new ideas for more effective treatment of triple-negative breast cancer and identifies novel targets for drug development.

Integration of TE Induces Cancer Specific Alternative Splicing Events

Alternative splicing of messenger RNA (mRNA) precursors contributes to genetic diversity by generating structurally and functionally distinct transcripts. In a disease state, alternative splicing promotes incidence and development of several cancer types through regulation of cancer-related biological processes. Transposable elements (TEs), having the genetic ability to jump to other regions of the genome, can bring about alternative splicing events in cancer. TEs can integrate into the genome, mostly in the intronic regions, and induce cancer-specific alternative splicing by adjusting various mechanisms, such as exonization, providing splicing donor/acceptor sites, alternative regulatory sequences or stop codons, and driving exon disruption or epigenetic regulation. Moreover, TEs can produce microRNAs (miRNAs) that control the proportion of transcripts by repressing translation or stimulating the degradation of transcripts at the post-transcriptional level. Notably, TE insertion creates a cancer-friendly environment by controlling the overall process of gene expression before and after transcription in cancer cells. This review emphasizes the correlative interaction between alternative splicing by TE integration and cancer-associated biological processes, suggesting a macroscopic mechanism controlling alternative splicing by TE insertion in cancer.

Myoglobin mutant with enhanced nitrite reductase activity regulates intracellular oxidative stress in human breast cancer cells

Heme proteins play vital roles in regulating the reactive oxygen/nitrogen species (ROS/RNS) levels in cells. In this study, we overexpressed human wild-type (WT) myoglobin (Mb) and its double mutant, F43H/H64A Mb with enhanced nitrite reductase (NIR) activity, in the typical representative triple-negative breast cancer cell, MDA-MB-231 cells. The results showed that the overexpression of F43H/H64A Mb increased the level of nitric oxide (NO) and the degree of oxidative stress, and then activated Akt/MAPK mediated apoptotic cascade, whereas WT Mb showed the opposite effect. This study indicates that Mb plays an important role in maintaining the balance of the cellular redox system and could thus be a valuable target for cancer therapy.

The cross-talk of autophagy and apoptosis in breast carcinoma: implications for novel therapies?

Breast cancer is still the most common cancer in women worldwide. Resistance to drugs and recurrence of the disease are two leading causes of failure in treatment. For a more efficient treatment of patients, the development of novel therapeutic regimes is needed. Recent studies indicate that modulation of autophagy in concert with apoptosis induction may provide a promising novel strategy in breast cancer treatment. Apoptosis and autophagy are two tightly regulated distinct cellular processes. To maintain tissue homeostasis abnormal cells are disposed largely by means of apoptosis. Autophagy, however, contributes to tissue homeostasis and cell fitness by scavenging of damaged organelles, lipids, proteins, and DNA. Defects in autophagy promote tumorigenesis, whereas upon tumor formation rapidly proliferating cancer cells may rely on autophagy to survive. Given that evasion of apoptosis is one of the characteristic hallmarks of cancer cells, inhibiting autophagy and promoting apoptosis can negatively influence cancer cell survival and increase cell death. Hence, combination of antiautophagic agents with the enhancement of apoptosis may restore apoptosis and provide a therapeutic advantage against breast cancer. In this review, we discuss the cross-talk of autophagy and apoptosis and the diverse facets of autophagy in breast cancer cells leading to novel models for more effective therapeutic strategies.

Emergence of Nanotechnology as a Powerful Cavalry against Triple-Negative Breast Cancer (TNBC)

Triple-negative breast cancer (TNBC) is considered one of the un-manageable types of breast cancer, involving devoid of estrogen, progesterone, and human epidermal growth factor receptor 2 (HER 2) receptors. Due to their ability of recurrence and metastasis, the management of TNBC remains a mainstay challenge, despite the advancements in cancer therapies. Conventional chemotherapy remains the only treatment regimen against TNBC and suffers several limitations such as low bioavailability, systemic toxicity, less targetability, and multi-drug resistance. Although various targeted therapies have been introduced to manage the hardship of TNBC, they still experience certain limitations associated with the survival benefits. The current research thus aimed at developing and improving the strategies for effective therapy against TNBC. Such strategies involved the emergence of nanoparticles. Nanoparticles are designated as nanocavalries, loaded with various agents (drugs, genes, etc.) to battle the progression and metastasis of TNBC along with overcoming the limitations experienced by conventional chemotherapy and targeted therapy. This article documents the treatment regimens of TNBC along with their efficacy towards different subtypes of TNBC, and the various nanotechnologies employed to increase the therapeutic outcome of FDA-approved drug regimens.

Carboxyl-Functionalized Carbon Nanotubes Loaded with Cisplatin Promote the Inhibition of PI3K/Akt Pathway and Suppress the Migration of Breast Cancer Cells

PI3K/Akt signaling is one of the most frequently dysregulated pathways in cancer, including triple-negative breast cancer. With considerable roles in tumor growth and proliferation, this pathway is studied as one of the main targets in controlling the therapies’ efficiency. Nowadays, the development of nanoparticle–drug conjugates attracts a great deal of attention due to the advantages they provide in cancer treatment. Hence, the main purpose of this study was to design a nanoconjugate based on single-walled carbon nanotubes functionalized with carboxyl groups (SWCNT-COOH) and cisplatin (CDDP) and to explore the potential of inhibiting the PI3K/Akt signaling pathway. MDA-MB-231 cells were exposed to various doses (0.01–2 µg/mL SWCNT-COOH and 0.00632–1.26 µg/mL CDDP) of SWCNT-COOH-CDDP and free components for 24 and 48 h. In vitro biological tests revealed that SWCNT-COOH-CDDP had a high cytotoxic effect, as shown by a time-dependent decrease in cell viability and the presence of a significant number of dead cells in MDA-MB-231 cultures at higher doses. Moreover, the nanoconjugates induced the downregulation of PI3K/Akt signaling, as revealed by the decreased expression of PI3K and p-Akt in parallel with PTEN activation, the promotion of Akt protein degradation, and inhibition of tumor cell migration.

iRGD Tumor-Penetrating Peptide-Modified Nano-Delivery System Based on a Marine Sulfated Polysaccharide for Enhanced Anti-Tumor Efficiency Against Breast Cancer

Background

Breast cancer is a common malignancy in women. Conventional clinical therapies for breast cancer all display moderate clinical efficacies and limitations. It is urgent to explore the novel and combined therapeutic strategies for breast cancer to meet clinical demand.

Methods

An iRGD tumor-penetrating peptide-modified nano-delivery system (denoted as iRGD-PSS@PBAE@JQ1/ORI nanoparticles) based on a marine sulfated polysaccharide was developed by codelivery of JQ1 (BET inhibitor) and oridonin (ORI, bioactive diterpenoid derived from traditional Chinese medicine herb). The iRGD-PSS@PBAE@JQ1/ORI NPs, surface modified with iRGD peptide conjugated propylene glycol alginate sodium sulfate (iRGD-PSS). The antitumor efficacy was evaluated both in vitro and in vivo.

Results

The prepared iRGD-PSS@PBAE@JQ1/ORI NPs effectively enhanced the tumor targeting and cellular internalization of JQ1 and ORI. Thus, JQ1 exerted the reversal effect on immune tolerance by decreasing the expression of PD-L1, while ORI displayed multiple antitumor effects, such as antiproliferation, inhibition of intracellular ROS production and inhibition of lactic acid secretion.

Conclusion

Our data revealed that iRGD peptide could significantly improve the cellular internalization and tumor penetration of the nano-delivery system. The combination of JQ1 and ORI could exert synergistic antitumor activities. Taken together, this study provides a multifunctional nanotherapeutic system to enhance the anti-tumor efficiency against breast cancer.

Key Factor Regulating Inflammatory Microenvironment, Metastasis, and Resistance in Breast Cancer: Interleukin-1 Signaling

Breast cancer is one of the top-ranked cancers for incidence and mortality worldwide. The biggest challenges in breast cancer treatment are metastasis and drug resistance, for which work on molecular evaluation, mechanism studies, and screening of therapeutic targets is ongoing. Factors that lead to inflammatory infiltration and immune system suppression in the tumor microenvironment are potential therapeutic targets. Interleukin-1 is known as a proinflammatory and immunostimulatory cytokine, which plays important roles in inflammatory diseases. Recent studies have shown that interleukin-1 cytokines drive the formation and maintenance of an inflammatory/immunosuppressive microenvironment through complex intercellular signal crosstalk and tight intracellular signal transduction, which were found to be potentially involved in the mechanism of metastasis and drug resistance of breast cancer. Some preclinical and clinical treatments or interventions to block the interleukin-1/interleukin-1 receptor system and its up- and downstream signaling cascades have also been proven effective. This study provides an overview of IL-1-mediated signal communication in breast cancer and discusses the potential of IL-1 as a therapeutic target especially for metastatic breast cancer and combination therapy and current problems, aiming at enlightening new ideas in the study of inflammatory cytokines and immune networks in the tumor microenvironment.

Combination of Chidamide-Mediated Epigenetic Modulation with Immunotherapy: Boosting Tumor Immunogenicity and Response to PD-1/PD-L1 Blockade

Improving tumor immunogenicity is critical for increasing the responsiveness of triple-negative breast cancer (TNBC) to anti-PD-(L)1 treatment. Here, we verified that chidamide (CHI), an epigenetic modulator, could elicit immunogenic cell death within TNBC to enhance cancer immunogenicity and elicit an antitumor immune response. Additionally, CHI increased the expression level of PD-L1, MHC I, and MHC II on cancer cells, which contributed to T-cell recognition and PD-1/PD-L1 blockade therapy response. The synergistic antitumor efficacy of CHI and PD-L1 blockade therapy was further explored through liposomes co-delivering CHI and BMS-202 (a small-molecule PD-L1 inhibitor). The liposomes possessed good biocompatibility, security, and controllable drug release and endowed therapeutics drugs with favorable tumor accumulation. Furthermore, the drug-loaded liposomes could obviously boost the antitumor immunity of TNBC through CHI-enhanced tumor immunogenicity and BMS-202-mediated PD-L1 blockade, thereby effectively inhibiting the growth of primary and metastatic tumors with an inhibitory rate of metastasis of up to 96%. In summary, this work provided a referable and optional approach for clinical antitumor therapy based on the combination of an epigenetic modulator and PD-1/PD-L1 blockade therapy.

Immunotherapy Treatment for Triple Negative Breast Cancer

Triple-negative breast cancer (TNBC) is considered one of the highest-risk subtypes of breast cancer and has dismal prognosis. Local recurrence rate after standard therapy in the early breast cancer setting can be upwards to 72% in 5 years, and in the metastatic setting, the 5-year overall survival is 12%. Due to the lack of receptor expression, there has been a paucity of targeted therapeutics available, with chemotherapy being the primary option for systemic treatment in both the neoadjuvant and metastatic setting. More recently, immunotherapy has revolutionized the landscape of cancer treatment, particularly immune checkpoint inhibitor (ICI) therapy, with FDA approval in over 20 types of cancer since 2011. Compared to other cancer types, breast cancer has been traditionally thought of as being immunologically cold; however, TNBC has demonstrated the most promise with immunotherapy use, a timely discovery due to its lack of targeted therapy options. In this review, we summarize the trials using checkpoint therapy in early and metastatic TNBC, as well as the development of biomarkers and the importance of immune related adverse events (IRAEs), in this disease process.

Triple Negative Breast Cancer: A Mountain Yet to Be Scaled Despite the Triumphs

Metastatic progression and tumor recurrence pertaining to TNBC are certainly the leading cause of breast cancer-related mortality; however, the mechanisms underlying TNBC chemoresistance, metastasis, and tumor relapse remain somewhat ambiguous. TNBCs show 77% of the overall 4-year survival rate compared to other breast cancer subtypes (82.7 to 92.5%). TNBC is the most aggressive subtype of breast cancer, with chemotherapy being the major approved treatment strategy. Activation of ABC transporters and DNA damage response genes alongside an enrichment of cancer stem cells and metabolic reprogramming upon chemotherapy contribute to the selection of chemoresistant cells, majorly responsible for the failure of anti-chemotherapeutic regime. These selected chemoresistant cells further lead to distant metastasis and tumor relapse. The present review discusses the approved standard of care and targetable molecular mechanisms in chemoresistance and provides a comprehensive update regarding the recent advances in TNBC management.

Suppression of molecular targets and antiproliferative effect of citronellal in triple-negative breast cancer cells

BACKGROUND

Triple-negative breast cancer (TNBC) requires targeted therapies to better manage and prevent metastatic mammary gland tumors. Due to the resistance problem associated with the approved drugs, researchers are now focusing on phytochemicals for the treatment of TNBC as they possess a pleiotropic mode of action and fewer side effects.

OBJECTIVE

To investigate the antiproliferative effect of citronellal in triple negative breast cancer cells.

METHOD

Anticancer potential of citronellal was explored by employing SRB, MTT and NRU antiproliferative assay. Further, the effect of citronellal was observed on molecular targets (Tubulin, COX-2 and LOX-5) utilizing in vitro and in silico methods. Furthermore, the efficacy of citronellal was examined on Ehrlich Ascites Carcinoma. In addition, the safety profiling of it was observed at 300 and 1000 mg/kg of body weight in mice.

RESULTS

Citronellal suppresses the growth of MDA-MB-231 cells by more than 50% in NRU assay and ~41% and 32% in SRB and MTT assay, respectively. Further, citronellal's effect was observed on molecular targets wherein it suppressed LOX-5 activity (IC50 40.63±2.27 µM) and prevented polymerization of microtubule (IC50 63.62 µM). The result was more prominent against LOX-5 as supported by molecular docking interaction studies, but a non-significant effect was observed at the transcriptional level. The efficacy of citronellal was also determined in Ehrlich Ascites Carcinoma (EAC) model, wherein it inhibited the growth of tumor cells (45.97%) at 75 mg/kg of body weight. It was non-toxic upto 1000 mg/kg of body weight in mice and did not cause significant lysis of erythrocytes.

CONCLUSION

These observations could provide experimental support for citronellal to be used as a chemopreventive agent for breast cancer.

High Prevalence of Triple-Negative Breast Cancer in Southern Shaanxi Province, China

Purpose

Describing the clinical features of patients with breast cancer in an area is important to provide the information for the local oncologist to make sound treatment plans. In this study, we explored the clinical features of breast cancer patients in Southern Shaanxi Province, China.

Patients and Methods

A total of 328 breast cancer patients between 2010 and 2015 were recruited at our hospital. Patients' clinical information and the results of the histopathological examination were collected. Independent sample t-test and Cox regression were used to analyze the data.

Results

The peak age onset of these patients was between 45 and 50. At diagnosis, 8.23% of patients were at clinical stage 1 and 29.57% were triple-negative breast cancer subtype. High expression of Ki-67 in these patients was found associated with triple-negative breast cancer. The 5-year survival rate in these patients was 66.4%, and the survival rate in stage 1 and 2 patients (88.2%) was significantly higher than that in stage 3 and4 (57.4%).

Conclusion

We here reported the clinical features of patients with breast cancer in Southern Shaanxi Province, China. The breast cancer patients in Southern Shaanxi Province showed a unique clinical feature.

Development and evaluation of poly adenosine 5'-diphosphate-ribose polymerase 1 immobilization-based receptor chromatography

Yanghe decoction is a traditional Chinese medicine prescription and has been used for breast cancer treatment for many years. However, the effective ingredients in the decoction have not been identified. The expression of poly(ADP-ribose) polymerase-1 is highly related to breast cancer. Using poly(ADP-ribose) polymerase-1 as a probe, we expressed the haloalkane dehalogenase-tagged protein in BL21(DE3) E. coli, immobilized it on hexachlorocaproic acid-modified macroporous silica gel, and established a poly(ADP-ribose) polymerase-1 chromatographic model. The feasibility of the model was verified by testing the retention behaviors of five drugs on the protein column. We applied the model in screening the bioactive components in yanghe decoction. Rutin, liquiritin, and a compound ([M-H]^- 681.7) were identified to be the potential bioactive ingredients. We studied the binding property between rutin and poly(ADP-ribose) polymerase-1 by injection amount dependent method, competitive studies, and molecular docking. We found that rutin can bind to the protein through the typical inhibitor binding site of the protein. Therefore, the chromatographic model is a useful tool to screen bioactive compounds from traditional Chinese medicine. The method is fast, reliable, and applicable to other functional proteins that can screen the potential lead compounds for the treatment of the related diseases.