Toll-like receptor 9 expression is associated with breast cancer sensitivity to the growth inhibitory effects of bisphosphonates in vitro and in vivo

CD73 regulates zoledronate-induced lymphocyte infiltration in triple-negative breast cancer tumors and lung metastases

Introduction

Bisphosphonates (BPs) are bone-protecting osteoclast inhibitors, typically used in the treatment of osteoporosis and skeletal complications of malignancies. When given in the adjuvant setting, these drugs may also prevent relapses and prolong overall survival in early breast cancer (EBC), specifically among postmenopausal patients. Because of these findings, adjuvant nitrogen-containing BPs (N-BPs), such as zoledronate (ZOL), are now the standard of care for high-risk EBC patients, but there are no benefit-associated biomarkers, and the efficacy remains low. BPs have been demonstrated to possess anti-tumor activities, but the mechanisms by which they provide the beneficial effects in EBC are not known.

Methods

We used stably transfected 4T1 breast cancer cells together with suppression of CD73 (sh-CD73) or control cells (sh-NT). We compared ZOL effects on tumor growth and infiltrating lymphocytes (TILs) into tumors and lung metastases using two mouse models. B cell depletion was performed using anti-CD20 antibody.

Results

Sh-CD73 4T1 cells were significantly more sensitive to the growth inhibitory effects of n-BPs in vitro. However, while ZOL-induced growth inhibition was similar between the tumor groups in vivo, ZOL enhanced B and T lymphocyte infiltration into the orthotopic tumors with down-regulated CD73. A similar trend was detected in lung metastases. ZOL-induced tumor growth inhibition was found to be augmented with B cell depletion in sh-NT tumors, but not in sh-CD73 tumors. As an internal control, ZOL effects on bone were similar in mice bearing both tumor groups.

Discussion

Taken together, these results indicate that ZOL modifies TILs in breast cancer, both in primary tumors and metastases. Our results further demonstrate that B cells may counteract the growth inhibitory effects of ZOL. However, all ZOL-induced TIL effects may be influenced by immunomodulatory characteristics of the tumor.

Synthesis of the biologically important dideuterium-labelled adenosine triphosphate analogue ApppI(d2)

The chemical synthesis of the dideuterium-labelled ATP analogue 1-adenosin-5’-yl-3-(3-methylbut-3-en-1,1-d₂-1-ol) triphosphoric acid diester (ApppI(d₂)) is described. ApppI has been reported to be an important mevalonate pathway metabolite, induced by nitrogen-containing bisphosphonates used for the treatment of several diseases related to the calcium metabolism, of which osteoporosis is the most well-known. The availability of ApppI(d₂) opens possibilities to quantitative measurements of ApppI in biological samples by mass spectrometry. The synthesized target compound ApppI(d₂) was purified by high-performance counter current chromatography and characterized by ¹H, ¹³C, and ³¹P NMR spectroscopy as well as high-resolution mass spectrometry.

Bisphosphonate-Based Conjugates and Derivatives as Potential Therapeutic Agents in Osteoporosis, Bone Cancer and Metastatic Bone Cancer

Metastatic bone cancer occurs in every type of cancer but is prevalent in lung, breast, and prostate cancers. These metastases can cause extensive morbidity, including a range of skeletal-related events, often painful and linked with substantial hospital resource usage. The treatment used is a combination of chemotherapy and surgery. However, anticancer drugs are still limited due to severe side effects, drug resistance, poor blood supply, and non-specific drug uptake, necessitating high toxic doses. Bisphosphonates are the main class of drugs utilized to inhibit metastatic bone cancer. It is also used for the treatment of osteoporosis and other bone diseases. However, bisphosphonate also suffers from serious side effects. Thus, there is a serious need to develop bisphosphonate conjugates with promising therapeutic outcomes for treating metastatic bone cancer and osteoporosis. This review article focuses on the biological outcomes of designed bisphosphonate-based conjugates for the treatment of metastatic bone cancer and osteoporosis.

A Review of Literature on Updates of Bisphosphonates Administration, Cancer Biomarkers for Bisphosphonate Therapy, and Bisphosphonate-related Osteonecrosis of the Jaw in Breast Cancer

Context: The emergence of bone health maintenance in breast cancer patients is known as an indispensable aspect in survival and morbidity improvement; therefore, bisphosphonates play a substantial role in the prevention/delaying of cancer treatment induced bone loss and skeletal-related events (SREs) in these patients, although this drug can cause necrosis of the jaw. In this article, we aimed at summarizing updated evidence on bisphosphonates administration, biomarkers representative of the efficacy of bisphosphonate therapy, and bisphosphonate-related osteonecrosis of the jaw (BRONJ) affection in patients involved in breast cancer. Methods: Associated published articles were searched for in EMBASE, MEDLINE, CDSR, PubMed, Google Scholar, and CINAHL, using the following keywords or, in the case of PubMed database, medical subject headings (MeSH): ‘Diphosphonate’, ‘osteonecrosis’, ‘breast cancer’, and ‘biomarker’ in the abstract or title, and was limited by "clinical trials, meta-analysis and randomized controlled trial” published in English language from 2015 to 2020-09-15. Results: Bisphosphonates depicted remarkable advantages in improving SREs, skeletal morbidity rate (SMR), survival rate, and treatment-emergent adverse events in breast cancer patients in almost all aspects of breast cancer therapy, from adjuvant therapy for the early stage breast cancer to bone metastatic breast cancer (BMBC). The identification of breast cancer biomarkers that are capable of reflecting the outcomes of bisphosphonates therapy is a highly advantageous aid in the optimal utilization of these drugs. Breast cancer biomarkers such as MAF, DOCK4, CD73, TLR9, and CAPG/GIPC1 composite illustrated a significant correlation with bisphosphonates administration. Medication-related osteonecrosis of the jaw (MRONJ) stands out as the most hazardous adverse event of the bisphosphonates with a rationally high incidence among breast cancer patients, which requires cautious prescription of bisphosphonates as well as regular dental health counseling for being prevented. Conclusions: Bisphosphonates are great weapons in the arsenal of breast cancer treatment and, therefore, comprehensive studying of their features leads to the optimal and safe administration of them. Unfortunately, as this procedure can cause necrosis of the jaw, dental procedures should be performed in these patients before starting bisphosphonate treatment.

Targeting Toll like Receptors in Cancer: Role of TLR Natural and Synthetic Modulators

Background:

Toll like receptors (TLRs) are a group of transmembrane receptors belonging to the broad class pattern recognition receptors (PRR), involved in recognition of Pathogen Associated Molecular Patterns (PAMPs) thereby inducing an immune response. Apart from these exogenous PAMPs, numerous endogenous PAMPs are also ligands for various TLRs thereby activating the TLR dependent immune response, subsequently leading to the onset of an inflammatory response. Prolonged activation of TLR by these endogenous PAMPs leads to chronic inflammatory insults to the body and which in turn alters the proliferative patterns of the cells, which ultimately leads to the development of cancer.

Objectives:

The present review aims to provide a detailed outline of the differential roles of various TLRs in cancer and the possible use of them as a therapeutic target.

Methods:

Data were collected from PubMed/Sciencedirect/Web of Science database and sorted; the latest literature on TLRs was incorporated in the review.

Results:

Among the different TLRs, few are reported to be anti-neoplastic, which controls the cell growth and multiplication in response to the endogenous signals. On the contrary, numerous studies have reported the procarcinogenic potentials of TLRs. Hence, TLRs have emerged as a potential target for the prevention and treatment of various types of cancers. Several molecules, such as monoclonal antibodies, small molecule inhibitors and natural products have shown promising anticancer potential by effectively modulating the TLR signalling.

Conclusion:

Toll-like receptors play vital roles in the process of carcinogenesis, hence TLR targeting is a promising approach for cancer prevention.

Toll-like Receptors as a Novel Therapeutic Target for Natural Products Against Chronic Diseases

Toll-like receptors (TLR) are one among the initial responders of the immune system which participate in the activation inflammatory processes. Several different types of TLR such as TLR2, TLR4, TLR7 and TLR9 have been identified in various cell types, each having distinct ligands like lipids, lipoproteins, nucleic acids and proteins. Though its prime concern is xenobiotic defences, TLR signalling has also recognized as an activator of inflammation and associated development of chronic degenerative disorders (CDDs) including obesity, type 2 diabetes mellitus (T2DM), fatty liver disease, cardiovascular and neurodegenerative disorders as well as various types of cancers. Numerous drugs are in use to prevent these disorders, which specifically inhibit different pathways associated with the development of CDDs. Compared to these drug targets, inhibition of TLR, which specifically responsible for the inflammatory insults has proven to be a better drug target. Several natural products have emerged as inhibitors of CDDs, which specifically targets TLR signalling, among these, many are in the clinical trials. This review is intended to summarize the recent progress on TLR association with CDDs and to list possible use of natural products, their combinations and their synthetic derivative in the prevention of TLR-driven CDD development.

Toll-Like Receptors Signaling in the Tumor Microenvironment

The involvement of inflammation in cancer progression is well-established. The immune system can play both tumor-promoting and -suppressive roles, and efforts to harness the immune system to help fight tumor growth are at the forefront of research. Of particular importance is the inflammatory profile at the site of the tumor, with respect to both the leukocyte population numbers, the phenotype of these cells, as well as the contribution of the tumor cells themselves. In this regard, the pro-inflammatory effects of pattern recognition receptor expression and activation in the tumor microenvironment have emerged as a relevant issue both for therapy and to understand tumor development.Pattern recognition receptors (PRRs) were originally recognized as components of immune cells, particularly innate immune cells, as detectors of pathogens. PRR signaling in immune cells activates them, inducing robust antimicrobial responses. In particular, toll-like receptors (TLRs) constitute a family of membrane-bound PRRs which can recognize pathogen-associated molecular patterns (PAMPs) carried by bacteria, virus, and fungi. In addition, PRRs can recognize products generated by stressed cells or damaged tissues, namely damage-associated molecular patterns or DAMPS. Taking into account the role of the immune system in fighting tumors together with the presence of immune cells in the microenvironment of different types of tumors, strategies to activate immune cells via PRR ligands have been envisioned as an anticancer therapeutic approach.In the last decades, it has been determined that PRRs are present and functional on nonimmune cells and that their activation in these cells contributes to the inflammation in the tumor microenvironment. Both tumor-promoting and antitumor effects have been observed when tumor cell PRRs are activated. This argues against nonspecific activation of PRR ligands in the tumor microenvironment as a therapeutic approach. Therefore, the use of PRR ligands for anticancer therapy might benefit from strategies that specifically deliver these ligands to immune cells, thus avoiding tumor cells in some settings. This review focuses on these aspects of TLR signaling in the tumor microenvironment.

Semi-preparative high-performance countercurrent chromatography method for the purification of chemically synthesized ATP analogue, ApppI

An efficient high-performance countercurrent chromatography (HPCCC) based method has been developed for the purification of chemically synthesized 1-adenosin-5'-yl 3-(3-methylbut-3-enyl)triphosphoric acid diester (ApppI). ApppI is an adenosine triphosphate (ATP) analogue with biological significance due to its varied actions in the body. ApppI was synthesized and purified as its tetrabutylammonium (TBA) salt and converted successfully into its more practical sodium salt form after purification. The amount of TBA hydroxide (2.0, 2.5 and 3.0 eq) used in the synthesis of ApppI was shown to exert an effect on the purification process with HPCCC and on the overall yield (8%, 16% and 22%, respectively). 1-Adenosin-5'-yl 3-(3-methylbut-3-enyl)diphosphoric acid diester (AppI) was also isolated as a side product.

Lipid Bilayer-Gated Mesoporous Silica Nanocarriers for Tumor-Targeted Delivery of Zoledronic Acid in Vivo

Zoledronic acid (ZOL) is a nitrogen-containing bisphosphonate used for the treatment of bone diseases and calcium metabolism. Anticancer activity of ZOL has been established, but its extraskeletal effects are limited due to its rapid uptake and accumulation to bone hydroxyapatite. In this work, we report on the development of tethered lipid bilayer-gated mesoporous silica nanocarriers (MSNs) for the incorporation, retention, and intracellular delivery of ZOL. The in vitro anticancer activity of ZOL-loaded nanocarriers was evaluated by cell viability assay and live-cell imaging. For in vivo delivery, the nanocarriers were tagged with folic acid to boost the affinity for breast cancer cells. Histological examination of the liver revealed no adverse off-target effects stemming from the nanocarriers. Importantly, nonspecific accumulation of ZOL within bone was not observed, which indicated in vivo stability of the tethered lipid bilayers. Further, the intravenously administered ZOL-loaded nanocarriers showed tumor growth suppression in breast cancer xenograft-bearing mice.

Synthesis of a Biologically Important Adenosine Triphosphate Analogue, ApppD

The chemical synthesis of a adenosine triphosphate analogue, 1-adenosin-5'-yl 3-(3-methylbut-2-enyl) triphosphoric acid diester (ApppD), is described. ApppD is known to be an active metabolite of the mevalonate pathway in the human body like its structural isomer isopentenyl ester of ATP (ApppI). Very recently, ApppI has been found to possess novel function(s); now it will also be possible to examine the effects of ApppD more precisely because it can be synthesized in reasonable amounts. 1-Adenosin-5'-yl 3-(3-methylbut-2-enyl) diphosphoric acid diester (AppD; a adenosine diphosphate analogue) was also isolated from the synthesis mixture. Both ApppD and AppD were characterized by ¹H, ¹³C, ³¹P NMR and mass spectrometry methods.