PD-L1 silencing inhibits triple-negative breast cancer development and upregulates T-cell-induced pro-inflammatory cytokines

PD-L1 intrinsically promotes the proliferation of breast cancer cells through the SKP2-p27/p21 axis

BACKGROUND

PD-L1 intrinsically promotes tumor progression through multiple mechanisms, which potentially leads to resistance to anti-PD-1/PD-L1 therapies. The intrinsic effect of PD-L1 on breast cancer (BC) cell proliferation has not been fully elucidated.

METHODS

we used proteomics, gene expression knockdown (KD), quantitative immunofluorescence (qIF), western blots, functional assays including colony-forming assay (CFA) and real-time cell analyzer (RTCA), and in vivo data using immunohistochemistry in breast cancer patients.

RESULTS

PD-L1 promoted BC cell proliferation by accelerating cell cycle entry at the G1-to-S phase transition. Global proteomic analysis of the differentially expressed nuclear proteins indicated the involvement of several proliferation-related molecules, including p21CIP1/WAF1. Western blotting and qIF demonstrated the higher expression of SKP2 and the lower expression of p21CIP1/WAF1 and p27Kip1 in PD-L1 expressing (PD-L1pos) cells as compared to PD-L1 KD (PD-L1KD) cells. Xenograft-derived cells and the TCGA BC dataset confirmed this relationship in vivo. Functionally, CFA and RTCA demonstrated the central role of SKP2 in promoting PD-L1-mediated proliferation. Finally, immunohistochemistry in 74 breast cancer patients confirmed PD-L1 and SKP-p21/p27 axis relationship, as it showed a highly statistically significant correlation between SKP2 and PD-L1 expression (p < 0.001), and both correlated significantly with the proliferation marker Ki-67 (p < 0.001). On the other hand, there was a statistically significant inverse relationship between PD-L1 and p21CIP1/WAF1 expression (p = 0.005). Importantly, double negativity for p21CIP1/WAF1 and p27Kip1 correlated significantly with PD-L1 (p < 0.001), SKP2 (p = 0.002), and Ki-67 (p = 0.002).

CONCLUSIONS

we have demonstrated the role of the SKP2-p27/p21 axis in intrinsic PD-L1-enhanced cell cycle progression. Inhibitors of SKP2 expression can alleviate resistance to ICPIs.

Sophora flavescens-Angelica sinensis in the treatment of eczema by inhibiting TLR4/MyD88/NF-κB pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Sophora flavescens Ait.-Angelica sinensis(Oliv.) Diels drug pairing (SA) is a transformed drug pairing from Shengui pill, a traditional Chinese medicine prescription in the ninth volume of Traditional Chinese Medicine classic "Gu Jin Yi Jian", which is famous for clearing heat, moistening dryness, and promoting blood circulation. It is commonly used in the treatment of eczema, a skin condition that causes itching and inflammation. Despite its widespread use, there is still limited research on the mechanism of how SA treats eczema. This paper aims to fill this gap by conducting animal experiments to uncover the mechanism behind SA's therapeutic effects on eczema. Our findings provide a solid foundation for the clinical use of this TCM prescription.

AIM OF THE STUDY

The basic purpose of this study is to clarify the therapeutic mechanism of Sophora flavescens-Angelica sinensis (SA) in the treatment and control of eczema.

MATERIALS AND METHODS

The chemical compositions of SA were analyzed using HPLC-Q-Orbitrap-MS. In vivo, a mouse model of eczema was created, and the serum levels of TNF-α and IL-1β were quantified using an enzyme-linked immunosorbent assay (ELISA). Hematoxylin and eosin (HE) staining was performed to assess the pathological state of the mouse skin, and immunohistochemical technique (IHC) was employed to estimate the contents of TNF-α, TLR4, and NF-κB semi-quantitatively. The expression levels of TLR4, MyD88, and NF-κB mRNA were determined through real-time quantitative polymerase chain reaction (qRT-PCR). Western Blotting was utilized to identify the protein levels of TLR4, MyD88, and NF-κB in mouse skin tissue.

RESULTS

SA identified 18 active chemicals, some of which were shown in vivo to inhibit the TLR4/MyD88/NF-κB signaling pathway while reducing serum levels of TNF-α and IL-1β, making them ideal agents for the treatment of eczema.

CONCLUSIONS

SA's anti-inflammatory properties are attributed to its ability to reduce serum levels of TNF-α and IL-1β, likewise inhibit the TLR4/MyD88/NF-κB signaling pathway.

Dual silencing of tumor-intrinsic VISTA and CTLA-4 stimulates T-cell mediated immune responses and inhibits MCF7 breast cancer development

BACKGROUND

As inhibitory immune checkpoint molecules, cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) and V-domain Ig suppressor of T-cell activation (VISTA) can be expressed in tumoral cells and facilitate immune evasion of tumoral cells. Herein, we studied the significance of tumor-intrinsic CTLA-4 and VISTA silencing in tumor development and inflammatory factors expression in a co-culture system with MCF7 and T-cells.

METHODS

MCF7 cells were transfected with 60 pmol of CTLA-siRNA, VISTA-siRNA, and dual VISTA-/CTLA-4-siRNA. The MTT assay was performed to study the effect of CTLA-4 and VISTA knockdown on the viability of MCF7 cells. Colony formation and wound-healing assays were performed to investigate the effect of CTLA-4 and VISTA silencing on the clonogenicity and migration of MCF7 cells. Flow cytometry was used to study the significance of CTLA-4 and VISTA knockdown on the apoptosis and cell cycle of MCF7 cells. Also, a co-culture system with MCF7 and T-cells was developed to study the expression levels of IL-2, IFN-γ, TNF-α, TGF-β, and IL-10 following CTLA-4 and VISTA knockdown. The expression levels of caspase3, Bax, Bcl2, and MMP-9 were also investigated using quantitative real-time PCR. Finally, the TCGA Breast Cancer and GSE45827 datasets were analyzed to study the potential prognostic values of VISTA and CTLA-4, their expression difference in luminal A breast cancer and non-tumoral tissues, and their correlation in luminal A breast cancer tissues.

RESULTS

Combined knockdown of tumor-intrinsic VISTA and CTLA-4 is superior in upregulating IL-2, IFN-γ, and TNF-α, downregulating TGF-β and IL-10 in T lymphocytes. Also, the combined silencing arrests the cell cycle at the sub-G1 phase, decreases migration, inhibits clonogenicity, and reduces cell viability of MCF7 cells. This combined treatment upregulates caspase 9 and BAX and downregulates MMP-9 in MCF7 cells. Our in-silico results have demonstrated a significant positive correlation between CTLA-4 and VISTA in luminal A breast cancer.

CONCLUSION

The additive effect of the combined knockdown of tumor-intrinsic VISTA and CTLA-4 can substantially upregulate pro-inflammatory factors, downregulate anti-inflammatory factors, and inhibit tumor development in MCF7 cells. The significant positive correlation between VISTA and CTLA-4 in luminal A breast cancer might support the idea that a network of inhibitory immune checkpoint molecules regulates anti-tumoral immune responses; thus, combinational immune checkpoint molecules blockade can be suggested.

Breaking Barriers: The Promise and Challenges of Immune Checkpoint Inhibitors in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is a highly aggressive malignancy with pronounced immunogenicity, exhibiting rapid proliferation and immune cell infiltration into the tumor microenvironment. TNBC's heterogeneity poses challenges to immunological treatments, inducing resistance mechanisms in the tumor microenvironment. Therapeutic modalities, including immune checkpoint inhibitors (ICIs) targeting PD-1, PD-L1, and CTLA-4, are explored in preclinical and clinical trials. Promising results emerge from combining ICIs with anti-TGF-β and VISTA, hindering TNBC tumor growth. TNBC cells employ complex evasion strategies involving interactions with stromal and immune cells, suppressing immune recognition through various cytokines, chemokines, and metabolites. The recent focus on unraveling humoral and cellular components aims to disrupt cancer crosstalk within the tumor microenvironment. This review identifies TNBC's latest resistance mechanisms, exploring potential targets for clinical trials to overcome immune checkpoint resistance and enhance patient survival rates.

Si Jun Zi decoction inhibits the growth of lung cancer by reducing the expression of PD-L1 through TLR4/MyD88/NF-κB pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Si Jun Zi decoction (SJZT) is a traditional Chinese medicine (TCM) formula with the effect of invigorating the spleen qi and replenishing qi. TCM believes that a strong spleen qi helps to strengthen lung qi. Lung cancer is often caused by a deficiency of lung qi. Based on this theory, TCM often applies SJZT to the treatment of lung cancer and has achieved remarkable results. However, the mechanism of SJZT in the treatment of lung cancer remains unclear and requires further study.

AIM OF THE STUDY

The main purpose of this study is to explore the mechanism of SJZT against lung cancer.

MATERIALS AND METHODS

In this study, the chemical constituents in SJZT were analyzed by UPLC-Q-Exactive-MS/MS. MTT and cell scratch test were used to determine the cell viability and inhibition of migration in vitro. The effect of SJZT on the expression of PD-L1 protein in A549 cells was detected by Western Blotting (WB). Apoptosis was detected by crystal violet staining. The mouse model of Lewis lung cancer was established in vivo, and the levels of serum TNF-α and IL-2 were detected by enzyme linked immunosorbent assay (ELISA). The protein levels of TLR4, MyD88, NF-κB and PD-L1 in tumor tissues of mice were detected by WB. Quantitative real-time PCR (qRT-PCR) was used to detect the levels of TLR4, MyD88, NF-κB and PD-L1 mRNA. Finally, hematoxylin and eosin (H&E) staining were used to detect the pathological status of tumor tissues in mice.

RESULTS

A total of 16 active chemical constituents were identified in SJZT. In vitro experiments showed that SJZT could inhibit the growth of A549, induce apoptosis and reduce the expression of PD-L1. In vivo experiments showed that SJZT regulated TLR4/MyD88/NF-κB signaling pathway, decreased the expression of PD-L1, and inhibited tumor growth.

CONCLUSIONS

SJZT inhibits the growth of lung cancer by regulating TLR4/MyD88/NF-κB signal pathway and reducing the expression of PD-L1.

The Cell-Autonomous Pro-Metastatic Activities of PD-L1 in Breast Cancer Are Regulated by N-Linked Glycosylation-Dependent Activation of STAT3 and STAT1

PD-L1 has been characterized as an inhibitory immune checkpoint, leading to the suppression of potential anti-tumor immune activities in many cancer types. In view of the relatively limited efficacy of immune checkpoint blockades against PD-L1 in breast cancer, our recent study addressed the possibility that in addition to its immune-inhibitory functions, PD-L1 promotes the pro-metastatic potential of the cancer cells themselves. Indeed, our published findings demonstrated that PD-L1 promoted pro-metastatic functions of breast cancer cells in a cell-autonomous manner, both in vitro and in vivo. These functions fully depended on the integrity of the S283 intracellular residue of PD-L1. Here, using siRNAs and the S283A-PD-L1 variant, we demonstrate that the cell-autonomous pro-metastatic functions of PD-L1-tumor cell proliferation and invasion, and release of the pro-metastatic chemokine CXCL8-required the activation of STAT3 and STAT1 in luminal A and triple-negative breast cancer cells. The cell-autonomous pro-metastatic functions of PD-L1 were potently impaired upon inhibition of N-linked glycosylation (kifunensine). Site-specific mutants at each of the N-linked glycosylation sites of PD-L1 (N35, N192, N200, and N219) revealed that they were all required for PD-L1-induced pro-metastatic functions to occur; the N219 site was the main regulator of STAT3 and STAT1 activation, with accompanying roles for N192 and N200 (depending on the cell type). Using a T cell-independent mouse system, we found that cells expressing N35A-PD-L1 and N219A-PD-L1 had a significantly lower tumorigenic and metastatic potential than cells expressing WT-PD-L1. TCGA analyses revealed significant associations between reduced survival and high levels of α-mannosidase II (inferring on N-linked glycosylation) in breast cancer patients. These findings suggest that N-linked glycosylation of PD-L1 may be used to screen for patients who are at greater risk of disease progression, and that modalities targeting N-linked glycosylated PD-L1 may lead to the inhibition of its cell-autonomous pro-metastatic functions and to lower tumor progression in breast cancer.

Potential of Dietary HDAC2i in Breast Cancer Patients Receiving PD-1/PD-L1 Inhibitors

Breast cancer (BC) is a lethal malignancy with high morbidity and mortality but lacks effective treatments thus far. Despite the introduction of immune checkpoint inhibitors (ICIs) (including PD-1/PD-L1 inhibitors), durable and optimal clinical benefits still remain elusive for a considerable number of BC patients. To break through such a dilemma, novel ICI-based combination therapy has been explored for enhancing the therapeutic effect. Recent evidence has just pointed out that the HDAC2 inhibitor (HDAC2i), which has been proven to exhibit an anti-cancer effect, can act as a sensitizer for ICIs therapy. Simultaneously, dietary intervention, as a crucial supportive therapy, has been reported to provide ingredients containing HDAC2 inhibitory activity. Thus, the novel integration of dietary intervention with ICIs therapy may offer promising possibilities for improving treatment outcomes. In this study, we first conducted the differential expression and prognostic analyses of HDAC2 and BC patients using the GENT2 and Kaplan-Meier plotter platform. Then, we summarized the potential diet candidates for such an integrated therapeutic strategy. This article not only provides a whole new therapeutic strategy for an HDAC2i-containing diet combined with PD-1/PD-L1 inhibitors for BC treatment, but also aims to ignite enthusiasm for exploring this field.

Integrins and Actions of Androgen in Breast Cancer

Androgen has been shown to regulate male physiological activities and cancer proliferation. It is used to antagonize estrogen-induced proliferative effects in breast cancer cells. However, evidence indicates that androgen can stimulate cancer cell growth in estrogen receptor (ER)-positive and ER-negative breast cancer cells via different types of receptors and different mechanisms. Androgen-induced cancer growth and metastasis link with different types of integrins. Integrin αvβ3 is predominantly expressed and activated in cancer cells and rapidly dividing endothelial cells. Programmed death-ligand 1 (PD-L1) also plays a vital role in cancer growth. The part of integrins in action with androgen in cancer cells is not fully mechanically understood. To clarify the interactions between androgen and integrin αvβ3, we carried out molecular modeling to explain the potential interactions of androgen with integrin αvβ3. The androgen-regulated mechanisms on PD-L1 and its effects were also addressed.

PD-1 Independent Role of PD-L1 in Triple-Negative Breast Cancer Progression

Triple-negative breast cancer (TNBC) is a type of breast malignancy characterized by a high proliferative rate and metastatic potential leading to treatment failure, relapse, and poor prognosis. Therefore, efforts are continuously being devoted to understanding its biology and identifying new potential targets. Programmed death-ligand 1 (PD-L1) is an immunosuppressive protein that inactivates T cells by binding to the inhibitory receptor programmed death-1 (PD-1). PD-L1 overexpression in cancer cells contributes to immune evasion and, subsequently, poor survival and prognosis in several cancers, including breast cancer. Apart from its inhibitory impact on T cells, this ligand is believed to have an intrinsic role in cancer cells. This study was performed to clarify the PD-1 independent role of PD-L1 in TNBC MDA-MB-231 cells by knocking out the PD-L1 using three designs of CRISPR-Cas9 lentiviral particles. Our study revealed that PD-L1 knockout significantly inhibited MDA-MB-231 cell proliferation and colony formation in vitro and tumor growth in the chick embryo chorioallantoic membrane (CAM) model in vivo. PD-L1 knockout also decreased the migration and invasion of MDA-MB-231 cells in vitro. We have shown that PD-L1 knockout MDA-MB-231 cells have low levels of p-Akt and p-ERK in addition to some of their downstream proteins, c-Fos, c-Myc, p21, survivin, and COX-2. Furthermore, PD-L1 knockout significantly decreased the expression of Snail and RhoA. This study shows the intrinsic role of PD-L1 in TNBC independently of its binding to PD-1 receptors on T cells. It may pave the way for developing novel therapeutic strategies using PD-L1 inhibitors alone and in combination to treat TNBC more effectively.

Silencing tumor-intrinsic HHLA2 potentiates the anti-tumoral effect of paclitaxel on MG63 cells: Another side of immune checkpoint

BACKGROUND

Osteosarcoma is common type of bone cancer; however, the prognosis of patients with metastatic osteosarcoma is poor. As a new inhibitory immune checkpoint molecule, HHLA2 is upregulated in osteosarcoma. Herein, we studied the significance of tumor-intrinsic HHLA2 in MG-63 growth. Also, we examined the influence of combined therapy of HHLA2 knockdown with paclitaxel on the apoptosis, cell cycle, migration, and stemness of MG-63 cells.

METHODS

The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay was performed to study the half-maximal inhibitory concentration (IC50) of paclitaxel and the cytotoxicity of HHLA2-small interfering RNA (siRNA) on MG-63 cells. The apoptosis and cell cycle were analyzed using flow cytometry. The wound-healing and colony formation assays were conducted to investigate the effect of paclitaxel and HHLA2 knockdown on the migration and stemness of MG-63 cells, respectively. QRT-PCR was used to determine the Bax, caspase-3, and Bcl-2 mRNA expression levels.

RESULTS

HHLA2 silencing has enhanced the chemosensitivity of MG-63 cells to paclitaxel. Besides, HHLA2 knockdown has increased the paclitaxel-induced cytotoxic effect on MG-63 cells. In terms of stimulating apoptosis, decreasing clonogenicity, halting the cell cycle at the sub G1 phase, and inhibiting migration, tumor-intrinsic HHLA2 silencing has increased these anti-tumor effects of paclitaxel on MG-63 cells. Besides, HHLA2 knockdown has potentiated paclitaxel-mediated Bcl-2 downregulation and paclitaxel-mediated caspase-3 and Bax upregulation in MG-63 cells.

CONCLUSION

Tumor-intrinsic HHLA2 knockdown increases the anti-tumoral effect of paclitaxel on MG-63 cells and enhances the chemosensitivity of MG-63 cells to paclitaxel.

Platycodin D induces neutrophil apoptosis by downregulating PD-L1 expression to inhibit breast cancer pulmonary metastasis

During breast cancer development, programmed cell death 1 ligand 1 (PD-L1) overexpression in neutrophils leads to delayed apoptosis and promotes neutrophil hyperproliferation in the lung to form a premetastatic niche, which is beneficial for pulmonary metastasis. Platycodin D (PlaD), a triterpenoid saponin with known anti-inflammatory and antitumor effects, has been reported to downregulate PD-L1 expression. This study aimed to investigate the inhibitory effect of PlaD on neutrophil PD-L1 in 4 T1 tumor-bearing mice and the potential mechanism of breast cancer pulmonary metastasis. In this study, the orthotopic 4 T1 murine mammary carcinoma model was administered 10 and 20 mg/kg PlaD by gavage. PlaD reduced the excess neutrophils and decreased their high migratory capacity in bone marrow, peripheral blood and lung tissue in the premetastatic period, thereby effectively inhibiting tumor growth and pulmonary metastasis. Moreover, PlaD inhibited the phosphatidylinositol-3-kinase (PI3K)/Akt pathway by decreasing the expression of PD-L1 in neutrophils and promoted neutrophil apoptosis. In vitro, PlaD treatment decreased the viability and inhibited migration of neutrophil-like dHL-60 in a dose-dependent manner. Similarly, PlaD inhibited the increase in PD-L1 induced by IFN-γ stimulation and subsequently induced apoptosis in dHL-60 cells. In conclusion, the administration of PlaD inhibited the PI3K/Akt signaling pathway by reducing the expression of PD-L1 in neutrophils. PlaD promoted neutrophil apoptosis, thereby inhibiting the establishment of a premetastatic niche and ultimately blocking the development of pulmonary metastasis.

Investigating the Effects of Indirect Coculture of Human Mesenchymal Stem Cells on the Migration of Breast Cancer Cells: A Systematic Review and Meta-Analysis

Purpose

Breast cancer is the most diagnosed cancer and the leading cause of cancer death in women globally, and mesenchymal stem cells have been widely implicated in tumour progression. This systematic review and meta-analysis seeks to identify and summarise existing literature on the effects of human mesenchymal stem cells (hMSCs) on the migration of breast cancer cells (BCCs) in vitro, to determine the direction of this relationship according to existing research and to identify the directions for future research.

Methods

A systematic literature search was conducting using a collection of databases, using the following search terms: in vitro AND mesenchymal stem cells AND breast cancer. Only studies that investigated the effects of human, unmodified MSCs on the migration of human, unmodified BCCs in vitro were included. Standardised mean differences (SMDs) were calculated to determine pooled effect sizes.

Results

This meta-analysis demonstrates that hMSCs (different sources combined) increase the migration of both MDA-MB-231 and MCF-7 cell lines in vitro (SMD = 1.84, P = .03 and SMD = 2.69, P < .00001, respectively). Importantly, the individual effects of hMSCs from different sources were also analysed and demonstrated that MSCs derived from human adipose tissue increase BCC migration (SMD = 1.34, P = .0002) and those derived from umbilical cord increased both MDA-MB-231 and MCF-7 migration (SMD = 3.93, P < .00001 and SMD = 3.01, P < .00001, respectively).

Conclusions

To our knowledge, this is the first systematic review and meta-analysis investigating and summarising the effects of hMSCs from different sources on the migration of BCCs, in vitro.

Immunotherapy: Review of the Existing Evidence and Challenges in Breast Cancer

Breast cancer (BC) is a representative malignant tumor that affects women across the world, and it is the main cause of cancer-related deaths in women. Although a large number of treatment methods have been developed for BC in recent years, the results are sometimes unsatisfying. In recent years, treatments of BC have been expanded with immunotherapy. In our article, we list some tumor markers related to immunotherapy for BC. Moreover, we introduce the existing relatively mature immunotherapy and the markers' pathogenesis are involved. The combination of immunotherapy and other therapies for BC are introduced in detail, including the combination of immunotherapy and chemotherapy, the combined use of immunosuppressants and chemotherapy drugs, immunotherapy and molecular targeted therapy. We summarize the clinical effects of these methods. In addition, this paper also makes a preliminary exploration of the combination of immunotherapy, radiotherapy, and nanotechnology for BC.

Silencing of COL3A1 represses proliferation, migration, invasion, and immune escape of triple negative breast cancer cells via down-regulating PD-L1 expression

This study is designed to illuminate the specific role and underlying mechanism of collagen type III alpha 1 chain (COL3A1) in triple negative breast cancer (TNBC). Quantitative real-time polymerase chain reaction was applied to examine mRNA expression of COL3A1. Western blot analysis was employed to determine protein levels of COL3A1, programmed death ligand 1 (PD-L1), Bcl-2, and cleaved caspase-3. Immunohistochemistry staining was utilized for assessing protein expression of Ki67 and COL3A1 in tissues. The proliferous capacity of cells was assessed through CCK-8 assay and 5-Ethynyl-2'-deoxyuridine assay. Cell apoptosis and the percentage of CD8+ T cells were measured using flow cytometry. Migration and invasion of TNBC cells were examined via transwell assay. Lactate dehydrogenase (LDH) release was measured via a LDH assay kit. For establishing a xenograft tumor model, MDA-MB-231 cells were injected into the flank of mice through subcutaneous injection. COL3A1 expression was raised in TNBC tissues and cells, and it was inversely associated with overall survival data of TNBC patients. COL3A1 downregulation repressed proliferation, invasion, migration, and immune escape of TNBC cells along with tumor growth of xenograft mice. In TNBC cells and tumor tissues of mice, protein expression of PD-L1 was reduced by COL3A1 knockdown. COL3A1 knockdown-mediated inhibitory effects on cell proliferation, migration, invasion, and immune escape were reversed by PD-L1 upregulation in vitro. Silencing of COL3A1 exerted an antitumor role in TNBC, implying its potential as a therapeutic target for TNBC.

A scoping review on the significance of programmed death-ligand 1-inhibiting microRNAs in non-small cell lung treatment: A single-cell RNA sequencing-based study

Background

The programmed death-ligand 1 (PD-L1)/PD-1 axis is one of the well-established inhibitory axes in regulating immune responses. Besides the significance of tumor-intrinsic PD-L1 expression in immune evasion, its oncogenic role has been implicated in various malignancies, like non-small cell lung cancer (NSCLC). As small non-coding RNAs, microRNAs (miRs) have pivotal roles in cancer biology. The current study aimed to systematically review the current knowledge about the significance of PD-L1-inhibiting miRs in NSCLC inhibition and their underlying mechanisms.

Materials and methods

We conducted the current scoping review based on the PRISMA-ScR statement. We systematically searched Embase, Scopus, Web of Science, PubMed, Ovid, EBSCO, ProQuest, Cochrane Library, African Index Medicus, and Pascal-Francis up to 4 April 2021. We also performed in silico tumor bulk RNA sequencing and single-cell RNA sequencing to further the current knowledge of the non-coding RNA-mediated tumor-intrinsic PD-L1 regulation and the PD-L1/PD-1 axis in NSCLC.

Results

The ectopic expression of hsa-miR-194-5p, hsa-miR-326, hsa-miR-526b-3p, hsa-miR-34a-5p, hsa-miR-34c-5p, hsa-miR-138-5p, hsa-miR-377-3p, hsa-let-7c-5p, hsa-miR-200a-3p, hsa-miR-200b-3p, hsa-miR-200c-3p, and hsa-miR-197-3p, as PD-L1-inhibiting miR, inhibits NSCLC development. These PD-L1-inhibiting miRs can substantially regulate the cell cycle, migration, clonogenicity, invasion, apoptosis, tumor chemosensitivity, and host anti-tumoral immune responses. Based on single-cell RNA sequencing results, PD-L1 inhibition might liberate the tumor-infiltrated CD8+ T-cells and dendritic cells (DCs)-mediated anti-tumoral immune responses via disrupting the PD-L1/PD-1 axis.

Conclusion

Given the promising preclinical results of these PD-L1-inhibiting miRs in inhibiting NSCLC development, their ectopic expression might improve NSCLC patients’ prognosis; however, further studies are needed to translate this approach into clinical practice.

Local Breast Microbiota: A "New" Player on the Block

Simple Summary

Microbiota plays a fundamental role in the induction, training and function of the human immune system. The interactions between microbiota and immune cells have consequences in several settings, namely in carcinogenesis but also in anticancer activity. Immunotherapy, already widely used in the treatment of several solid cancers, modulates the action of the immune system, promoting antitumour effects. Recently, there has been a growing interest in studying the microbiota composition as a possible modulator of the tumour microenvironment and consequently of the response to certain therapies such as immunotherapy.

Abstract

The tumour microenvironment (TME) comprises a complex ecosystem of different cell types, including immune cells, cells of the vasculature and lymphatic system, cancer-associated fibroblasts, pericytes, and adipocytes. Cancer proliferation, invasion, metastasis, drug resistance and immune escape are all influenced by the dynamic interaction between cancer cells and TME. Microbes, such as bacteria, fungi, viruses, archaea and protists, found within tumour tissues, constitute the intratumour microbiota, which is tumour type-specific and distinct among patients with different clinical outcomes. Growing evidence reveals a significant relevance of local microbiota in the colon, liver, breast, lung, oral cavity and pancreas carcinogenesis. Moreover, there is a growing interest in the tumour immune microenvironment (TIME) pointed out in several cross-sectional studies on the correlation between microbiota and TME. It is now known that microorganisms have the capacity to change the density and function of anticancer and suppressive immune cells, enabling the promotion of an inflammatory environment. As immunotherapy (such as immune checkpoint inhibitors) is becoming a promising therapy using TIME as a therapeutic target, the analysis and comprehension of local microbiota and its modulating strategies can help improve cancer treatments.

Dendritic cell-based cancer immunotherapy in the era of immune checkpoint inhibitors: From bench to bedside

Dendritic cells (DCs) can present tumoral antigens to T-cells and stimulate T-cell-mediated anti-tumoral immune responses. In addition to uptaking, processing, and presenting tumoral antigens to T-cells, co-stimulatory signals have to be established between DCs with T-cells to develop anti-tumoral immune responses. However, most of the tumor-infiltrated immune cells are immunosuppressive in the tumor microenvironment (TME), paving the way for immune evasion of tumor cells. This immunosuppressive TME has also been implicated in suppressing the DC-mediated anti-tumoral immune responses, as well. Various factors, i.e., immunoregulatory cells, metabolic factors, tumor-derived immunosuppressive factors, and inhibitory immune checkpoint molecules, have been implicated in developing the immunosuppressive TME. Herein, we aimed to review the biology of DCs in developing T-cell-mediated anti-tumoral immune responses, the significance of immunoregulatory cells in the TME, metabolic barriers contributing to DCs dysfunction in the TME, tumor-derived immunosuppressive factors, and inhibitory immune checkpoint molecules in DC-based cell therapy outcomes. With reviewing the ongoing clinical trials, we also proposed a novel therapeutic strategy to increase the efficacy of DC-based cell therapy. Indeed, the combination of DC-based cell therapy with monoclonal antibodies against novel immune checkpoint molecules can be a promising strategy to increase the response rate of patients with cancers.

Tumor Cell-Autonomous Pro-Metastatic Activities of PD-L1 in Human Breast Cancer Are Mediated by PD-L1-S283 and Chemokine Axes

Simple Summary

Triple-negative breast cancer (TNBC) is an aggressive disease that responds in a limited manner to immune checkpoint blockades targeting the PD-L1/PD-1 axis, suggesting that PD-L1 potentiates TNBC progression via pathways not related to immune suppression. We demonstrated that, in human breast cancer cells, PD-L1 expression increased in a cell-autonomous manner tumor cell growth, invasion and release of pro-metastatic factors; these activities were elevated by exposure to PD-1 and were markedly impaired in S283-mutated PD-L1-expressing cells. Invasion of WT-PD-L1-expressing TNBC cells depended on autocrine chemokine circuits, involving CXCR1/2, CCR2, CCR5 and their ligands. In T cell-deficient mice, WT-PD-L1 exhibited increased tumor growth and metastasis by TNBC cells, whereas S283A-PD-L1-expressing cells showed a very poor tumorigenic and metastatic profile. These findings on cell-autonomous and PD-1-induced pro-metastatic activities of PD-L1 in cancer cells suggest that treatments targeting PD-L1 could improve the efficacy of immune-targeting checkpoint inhibitors, e.g., anti-PD-1 or anti-CTLA-4 in TNBC.

Abstract

Therapies targeting the PD-L1/PD-1 axis have recently been introduced to triple-negative breast cancer (TNBC) with limited efficacy, suggesting that this axis promotes tumor progression through mechanisms other than immune suppression. Here, we over-expressed WT-PD-L1 in human TNBC cells (express endogenous PD-L1) and in luminal-A breast cancer cells (no endogenous PD-L1 expression) and demonstrated that cell-autonomous PD-L1 activities lead to increased tumor cell growth, invasion and release of pro-metastatic factors (CXCL8, sICAM-1, GM-CSF). These activities were promoted by PD-1 and were inhibited by mutating S283 in PD-L1. Invasion of WT-PD-L1-cells required signaling by chemokine receptors CXCR1/2, CCR2 and CCR5 through autocrine circuits involving CXCL8, CCL2 and CCL5. Studies with T cell-deficient mice demonstrated that cell-autonomous WT-PD-L1 activities in TNBC cells increased tumor growth and metastasis compared to knock-out (KO)-PD-L1-cells, whereas S283A-PD-L1-expressing cells had minimal ability to form tumors and did not metastasize. Overall, our findings reveal autonomous and PD-1-induced tumor-promoting activities of PD-L1 that depend on S283 and on chemokine circuits. These results suggest that TNBC patients whose tumors express PD-L1 could benefit from therapies that prevent immune suppression by targeting PD-1/CTLA-4, alongside with antibodies to PD-L1, which would allow maximal impact by mainly targeting the cancer cells.

Silencing tumor-intrinsic CD73 enhances the chemosensitivity of NSCLC and potentiates the anti-tumoral effects of cisplatin: An in vitro study

AIMS

Besides suppressing anti-tumoral immune responses, tumor-intrinsic inhibitory immune checkpoints have been implicated in tumor development. Herein, we aimed to investigate the significance of tumor-intrinsic CD73, as an inhibitory immune checkpoint, in non-small cell lung cancer (NSCLC) development and propose a novel therapeutic approach.

MAIN METHODS

We investigated the cell viability, chemosensitivity, apoptosis, migration, and the cell cycle of A-549 and NCI-H1299 following treatment with cisplatin and CD73-small interfering RNA (siRNA) transfection. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay was used to study the viability of studied groups and chemosensitivity of tumoral cells. Flow cytometry and 4',6-diamidino-2-phenylindole (DAPI) staining were used to investigate the apoptosis of NSCLC cells. Flow cytometry and the wound-healing assay were used to investigate the cell cycle and migration of NSCLC cells, respectively. The mRNA expression levels of c-Myc, caspase 3, ROCK, and MMP-9 were investigated to study the underlying molecular mechanism.

KEY FINDINGS

CD73-siRNA transfection has significantly decreased the cell viability and enhanced the chemosensitivity of A-549 and NCI-H1299 cells to cisplatin. CD73-siRNA has considerably stimulated apoptosis, arrested the cell cycle, inhibited tumor migration, downregulated the mRNA expression of c-Myc, MMP-9, and ROCK, and upregulated caspase 3 expression in NSCLC cells. Besides, combined cisplatin therapy with CD73-siRNA transfection has potentiated the aforementioned anti-tumoral effects of cisplatin on NSCLC cells.

SIGNIFICANCE

Besides suppressing anti-tumoral immune responses, tumor-intrinsic CD73 can facilitate NSCLC development, and the combined cisplatin therapy with CD73-siRNA transfection can substantially enhance the chemosensitivity of NSCLC to cisplatin and potentiates cisplatin-induced anti-tumoral effects on NSCLC.

Photodynamic Therapy with Zinc Phthalocyanine Inhibits the Stemness and Development of Colorectal Cancer: Time to Overcome the Challenging Barriers?

Photodynamic therapy (PDT) is a light-based cancer therapy approach that has shown promising results in treating various malignancies. Growing evidence indicates that cancer stem cells (CSCs) are implicated in tumor recurrence, metastasis, and cancer therapy resistance in colorectal cancer (CRC); thus, targeting these cells can ameliorate the prognosis of affected patients. Based on our bioinformatics results, SOX2 overexpression is significantly associated with inferior disease-specific survival and worsened the progression-free interval of CRC patients. Our results demonstrate that zinc phthalocyanine (ZnPc)-PDT with 12 J/cm2 or 24 J/cm2 irradiation can substantially decrease tumor migration via downregulating MMP9 and ROCK1 and inhibit the clonogenicity of SW480 cells via downregulating CD44 and SOX2. Despite inhibiting clonogenicity, ZnPc-PDT with 12 J/cm2 irradiation fails to downregulate CD44 expression in SW480 cells. Our results indicate that ZnPc-PDT with 12 J/cm2 or 24 J/cm2 irradiation can substantially reduce the cell viability of SW480 cells and stimulate autophagy in the tumoral cells. Moreover, our results show that ZnPc-PDT with 12 J/cm2 or 24 J/cm2 irradiation can substantially arrest the cell cycle at the sub-G1 level, stimulate the intrinsic apoptosis pathway via upregulating caspase-3 and caspase-9 and downregulating Bcl-2. Indeed, our bioinformatics results show considerable interactions between the studied CSC-related genes with the studied migration- and apoptosis-related genes. Collectively, the current study highlights the potential role of ZnPc-PDT in inhibiting stemness and CRC development, which can ameliorate the prognosis of CRC patients.

The combined therapy of miR-383-5p restoration and paclitaxel for treating MDA-MB-231 breast cancer

The deregulation of microRNAs (miRs) has been identified in tumor development. Indeed, the restoration of tumor-suppressive miRs has been associated with inhibited tumor development in various cancers. Herein, we aimed to evaluate the impact of combined miR-383-5p restoration, as a tumor-suppressive miR, with taxol therapy in suppressing MDA-MB-231 breast cancer development. MDA-MB-231 cell line was restored with miR-383-5p and treated with paclitaxel both in combined and separate manners. The MTT experiment was carried out to measure the cytotoxicity of the therapeutic approaches on the tumoral cells. Besides, flow cytometry was conducted to assess apoptosis and cell cycle status following the treatments. Furthermore, the expression levels of critical factors contributed to tumor proliferation, migration, apoptosis were investigated via the qRT-PCR and western blotting techniques. The outcomes pointed out that the miR-383-5p might substantially enhance the chemosensitivity of MDA-MB-231 to taxol. Besides, miR-383-5p restoration and the combined therapy of miR-383-5p restoration with paclitaxel could remarkably increase apoptosis, decrease cell viability, arrest the cell cycle, inhibit clonogenicity, suppress tumor migration, suppress the PI3K/Akt signaling pathway, and down-regulate PD-L1 expression of BC cells. The restoration of miR-383-5p can enhance the chemosensitivity of MDA-MB-231 cells to taxol. Despite the anti-tumoral effects of miR-383-5p restoration on MDA-MB-231 breast cancer development, the combined therapy of miR-383-5p restoration with paclitaxel can be more effective in repressing MDA-MB-231 breast cancer development.

The effects of chemotherapeutic drugs on PD-L1 gene expression in breast cancer cell lines

Breast cancer is the most common cancer among women in terms of prevalence and mortality, and chemotherapy is one of the most effective treatments at higher stages. However, resistance to chemotherapy is the main obstacle in the treatment of this cancer. Accumulated evidence identified the PD-L1 protein as an essential protein in the development of different cancers. Abnormal expression of this protein in various tumor cells is linked to cancer development and inhibiting the function of immune cells, which correlated with reduced beneficial effects of chemotherapy drugs. In the present study, the effects of common chemotherapy drugs including doxorubicin, paclitaxel, and docetaxel on the expression of the PD-L1 gene were investigated by qRT-PCR before and after the treatment with these drugs in MD231, MD468, SKBR3 breast cancer cell lines. Also, the MTT test was applied to examine the effects of drugs on the growth and proliferation of cancer cells considering PD-L1 expression. The expression of the PD-L1 gene increased after 24 and 48 h of treatment with chemotherapy drugs. The obtained results indicate the enhancing effects of chemotherapy drugs on PD-L1 gene expression, which have a suppressive effect on the immune system against breast cancer. The use of these drugs as the first line of chemotherapy in triple-negative breast cancer is not recommended. However, there is still a need for further experimental and clinical research on the exact effects of these drugs on undesired immune cells exhaustion in breast cancer therapy.

A Systematic Review to Clarify the Prognostic Values of CD44 and CD44+CD24- Phenotype in Triple-Negative Breast Cancer Patients: Lessons Learned and The Road Ahead

As a unique population of tumor bulk, cancer stem cells have been implicated in tumor relapse and chemoresistance in triple-negative breast cancer (TNBC). Therefore, understanding the phenotype of cancer stem cells can pave the way for introducing novel molecular targeted therapies for treating TNBC patients. Preclinical studies have identified CD44⁺CD24^-/low as a cancer stem cell phenotype; however, clinical studies have reported seemingly controversial results regarding the prognostic values of CD44 and CD44⁺CD24^-/low phenotype in TNBC patients. To critically review the clinicopathological significance and prognostic values of CD44 and CD44⁺CD24^-/low phenotype in TNBC patients, the Scopus, Embase, PubMed, and Web of Science databases were systematically searched to obtain the relevant records published before 20 October 2020. Based on nine included studies, CD44 and CD44⁺CD24^-/low phenotype are associated with inferior prognosis in TNBC patients. Moreover, these cancer stem cell markers have been associated with advanced tumor stage, tumor size, higher tumor grade, tumor metastasis, and lymphatic involvement in TNBC patients. Our evidence has also indicated that, unlike the treatment-naïve TNBC patients, the tumoral cells of chemoradiotherapy-treated TNBC patients can upregulate the CD44⁺CD24^-/low phenotype and establish an inverse association with androgen receptor (AR), leading to the inferior prognosis of affected patients. In summary, CD44 and CD44⁺CD24^-/low phenotype can be utilized to determine TNBC patients' prognosis in the pathology department as a routine practice, and targeting these phenotypes can substantially improve the prognosis of TNBC patients.

Histone deacetylase 2 knockout suppresses immune escape of triple-negative breast cancer cells via downregulating PD-L1 expression

The PD-L1 overexpression is an important event of immune escape and metastasis in triple-negative breast cancer (TNBC), but the molecular mechanism remains to be determined. Interferon gamma (IFNγ) represents a major driving force behind PD-L1 expression in tumor microenvironment, and histone deacetylase 2 (HDAC2) is required for IFN signaling. Here, we investigated the regulation of HDAC2 on the IFNγ-induced PD-L1 expression in TNBC cells. We found the HDAC2 and PD-L1 expression in TNBC was significantly higher than that in non-TNBC, and HDAC2 was positively correlated with PD-L1 expression. HDAC2 promoted PD-L1 induction by upregulating the phosphorylation of JAK1, JAK2, and STAT1, as well as the translocation of STAT1 to the nucleus and the recruitment of STAT1 to the PD-L1 promoter. Meanwhile, HDAC2 was recruited to the PD-L1 promoter by STAT1, and HDAC2 knockout compromised IFNγ-induced upregulation of H3K27, H3K9 acetylation, and the BRD4 recruitment in PD-L1 promoter. In addition, significant inhibition of proliferation, colony formation, migration, and cell cycle of TNBC cells were observed following knockout of HDAC2 in vitro. Furthermore, HDAC2 knockout reduced IFNγ-induced PD-L1 expression, lymphocyte infiltration, and retarded tumor growth and metastasis in the breast cancer mouse models. This study may provide evidence that HDAC2 promotes IFNγ-induced PD-L1 expression, suggesting a way for enhanced antitumor immunity when targeting the HDAC2 in TNBC.

A Systematic Review on the Therapeutic Potentiality of PD-L1-Inhibiting MicroRNAs for Triple-Negative Breast Cancer: Toward Single-Cell Sequencing-Guided Biomimetic Delivery

The programmed death-ligand 1 (PD-L1)/programmed cell death protein 1 (PD-1) is a well-established inhibitory immune checkpoint axis in triple-negative breast cancer (TNBC). Growing evidence indicates that tumoral PD-L1 can lead to TNBC development. Although conventional immune checkpoint inhibitors have improved TNBC patients’ prognosis, their effect is mainly focused on improving anti-tumoral immune responses without substantially regulating oncogenic signaling pathways in tumoral cells. Moreover, the conventional immune checkpoint inhibitors cannot impede the de novo expression of oncoproteins, like PD-L1, in tumoral cells. Accumulating evidence has indicated that the restoration of specific microRNAs (miRs) can downregulate tumoral PD-L1 and inhibit TNBC development. Since miRs can target multiple mRNAs, miR-based gene therapy can be an appealing approach to inhibit the de novo expression of oncoproteins, like PD-L1, restore anti-tumoral immune responses, and regulate various intracellular singling pathways in TNBC. Therefore, we conducted the current systematic review based on the preferred reporting items for systematic reviews and meta-analyses (PRISMA) to provide a comprehensive and unbiased synthesis of currently available evidence regarding the effect of PD-L1-inhibiting miRs restoration on TNBC development and tumor microenvironment. For this purpose, we systematically searched the Cochrane Library, Embase, Scopus, PubMed, ProQuest, Web of Science, Ovid, and IranDoc databases to obtain the relevant peer-reviewed studies published before 25 May 2021. Based on the current evidence, the restoration of miR-424-5p, miR-138-5p, miR-570-3p, miR-200c-3p, miR-383-5p, miR-34a-5p, miR-3609, miR-195-5p, and miR-497-5p can inhibit tumoral PD-L1 expression, transform immunosuppressive tumor microenvironment into the pro-inflammatory tumor microenvironment, inhibit tumor proliferation, suppress tumor migration, enhance chemosensitivity of tumoral cells, stimulate tumor apoptosis, arrest cell cycle, repress the clonogenicity of tumoral cells, and regulate various oncogenic signaling pathways in TNBC cells. Concerning the biocompatibility of biomimetic carriers and the valuable insights provided by the single-cell sequencing technologies, single-cell sequencing-guided biomimetic delivery of these PD-L1-inhibiting miRs can decrease the toxicity of traditional approaches, increase the specificity of miR-delivery, enhance the efficacy of miR delivery, and provide the affected patients with personalized cancer therapy.