Aberrant expression of the hematopoietic-restricted minor histocompatibility antigen LRH-1 on solid tumors results in efficient cytotoxic T cell-mediated lysis

P2 purinergic receptors regulate the progression of colorectal cancer

More and more studies have revealed that P2 purinergic receptors play a key role in the progression of colorectal cancer (CRC). P2X and P2Y purinergic receptors can be used as promoters and regulators of CRC and play a dual role in the progression of CRC. CRC microenvironment is rich in ATP and its cleavage products (ADP, AMP, Ado), which act as activators of P2X and P2Y purinergic receptors. The activation of P2X and P2Y purinergic receptors regulates the progression of CRC mainly by regulating the function of immune cells and mediating different signal pathways. In this paper, we focus on the specific mechanisms and functional roles of P2X7, P2Y12, and P2Y2 receptors in the growth and progression of CRC. The antagonistic effects of these selective antagonists of P2X purinergic receptors on the growth, invasion, and metastasis of CRC were further discussed. Moreover, different studies have reported that P2X7 receptor can be used as an effective predictor of patients with CRC. All these indicate that P2 purinergic receptors are a key regulator of CRC. Therefore, antagonizing P2 purinergic receptors may be an innovative treatment for CRC.

Dihydropyridines Potentiate ATP-Induced Currents Mediated by the Full-Length Human P2X5 Receptor

The P2X5 receptor, an ATP-gated cation channel, is believed to be involved in tumor development, inflammatory bone loss and inflammasome activation after bacterial infection. Therefore, it is a worthwhile pharmacological target to treat the corresponding diseases, especially in minority populations that have a gene variant coding for functional homotrimeric P2X5 channels. Here, we investigated the effects of dihydropyridines on the human full-length P2X5 receptor (hP2X5^FL) heterologously expressed in Xenopus oocytes using the two-microelectrode voltage clamp method. Agonist dependency, kinetics and permeation behavior, including Cl⁻ permeability, were similar to hP2X5^FL expressed in HEK293 or 1321N1 cells. Additionally, 1,4-dihydropyridines have been shown to interact with various other purinergic receptors, and we have examined them as potential hP2X5 modulators. Of seven commercially available and four newly synthesized dihydropyridines tested at hP2X5^FL, only amlodipine exerted an inhibitory effect, but only at a high concentration of 300 µM. Isradipine and—even more—nimodipine stimulated ATP-induced currents in the low micromolar range. We conclude that common dihydropyridines or four new derivatives of amlodipine are not suitable as hP2X5 antagonists, but amlodipine might serve as a lead for future synthesis to increase its affinity. Furthermore, a side effect of nimodipine therapy could be a stimulatory effect on inflammatory processes.

Susceptibility Genes and Chromosomal Regions Associated With Non-Syndromic Familial Non-Medullary Thyroid Carcinoma: Some Pathogenetic and Diagnostic Keys

Thyroid cancer is the malignant tumor that is increasing most rapidly in the world, mainly at the expense of sporadic papillary thyroid carcinoma. The somatic alterations involved in the pathogenesis of sporadic follicular cell derived tumors are well recognized, while the predisposing alterations implicated in hereditary follicular tumors are less well known. Since the genetic background of syndromic familial non-medullary carcinoma has been well established, here we review the pathogenesis of non-syndromic familial non-medullary carcinoma emphasizing those aspects that may be useful in clinical and pathological diagnosis. Non-syndromic familial non-medullary carcinoma has a complex and heterogeneous genetic basis involving several genes and loci with a monogenic or polygenic inheritance model. Most cases are papillary thyroid carcinoma (classic and follicular variant), usually accompanied by benign thyroid nodules (follicular thyroid adenoma and/or multinodular goiter). The possible diagnostic and prognostic usefulness of the changes in the expression and/or translocation of various proteins secondary to several mutations reported in this setting requires further confirmation. Given that non-syndromic familial non-medullary carcinoma and sporadic non-medullary thyroid carcinoma share the same morphology and somatic mutations, the same targeted therapies could be used at present, if necessary, until more specific targeted treatments become available.

P2X Receptors: Potential Therapeutic Targets for Symptoms Associated With Lung Cancer - A Mini Review

Symptoms associated with lung cancer mainly consist of cancer-associated pain, cough, fatigue, and dyspnea. However, underlying mechanisms of lung cancer symptom clusters remain unclear. There remains a paucity of effective treatment to ameliorate debilitating symptoms and improve the quality of life of lung cancer survivors. Recently, extracellular ATP and its receptors have attracted increasing attention among researchers in the field of oncology. Extracellular ATP in the tumor microenvironment is associated with tumor cell metabolism, proliferation, and metastasis by driving inflammation and neurotransmission via P2 purinergic signaling. Accordingly, ATP gated P2X receptors expressed on tumor cells, immune cells, and neurons play a vital role in modulating tumor development, invasion, progression, and related symptoms. P2 purinergic signaling is involved in the development of different lung cancer-related symptoms. In this review, we summarize recent findings to illustrate the role of P2X receptors in tumor proliferation, progression, metastasis, and lung cancer- related symptoms, providing an outline of potential anti-neoplastic activity of P2X receptor antagonists. Furthermore, compared with opioids, P2X receptor antagonists appear to be innovative therapeutic interventions for managing cancer symptom clusters with fewer side effects.

The current status and perspectives regarding the clinical implication of intracellular calcium in breast cancer

Calcium ions (Ca²⁺ ) act as second messengers in intracellular signaling. Ca²⁺ pumps, channels, sensors, and calcium binding proteins, regulate the concentrations of intracellular Ca²⁺ as a key regulator of important cellular processes such as gene expression, proliferation, differentiation, DNA repair, apoptosis, metastasis, and hormone secretion. Intracellular Ca²⁺ also influences the functions of several organelles, that include: the endoplasmic reticulum, mitochondria, the Golgi, and cell membrane both in normal and breast cancer cells. In breast cancer, the disruption of intracellular: Ca²⁺ homeostasis may cause tumor progression by affecting key factors/pathways including phospholipase C (PLC), inositol 1,4,5-trisphosphate (IP3), calmodulin (CaM), nuclear factor of activated T-cells (NFAT), calpain, calmodulin-dependent protein kinase II (CaMKII), mitogen-activated protein kinase (MAPK), epithelial-mesenchymal transition (EMT), vascular endothelial growth factor (VEGF), poly (ADP-Ribose) polymerase-1 (PARP1), estrogen, and estrogen receptor. Because the foregoing molecules play crucial roles in breast cancer, the factors/pathways influencing intracellular Ca²⁺ concentrations are putative targets for cancer treatment, using drugs such as Mephebrindole, Tilapia piscidin 4, Nifetepimine, Paricalcitol, and Prednisolone. We have explored the factors/pathways which are related to breast cancer and Ca²⁺ homeostasis and signaling in this review, and also discussed their potential as biomarkers for breast cancer staging, prognosis, and therapy.

Calcium influx pathways in breast cancer: opportunities for pharmacological intervention

Ca(2+) influx through Ca(2+) permeable ion channels is a key trigger and regulator of a diverse set of cellular events, such as neurotransmitter release and muscle contraction. Ca(2+) influx is also a regulator of processes relevant to cancer, including cellular proliferation and migration. This review focuses on calcium influx in breast cancer cells as well as the potential for pharmacological modulators of specific Ca(2+) influx channels to represent future agents for breast cancer therapy. Altered expression of specific calcium permeable ion channels is present in some breast cancers. In some cases, such changes can be related to breast cancer subtype and even prognosis. In vitro and in vivo models have now helped identify specific Ca(2+) channels that play important roles in the proliferation and invasiveness of breast cancer cells. However, some aspects of our understanding of Ca(2+) influx in breast cancer still require further study. These include identifying the mechanisms responsible for altered expression and the most effective therapeutic strategy to target breast cancer cells through specific Ca(2+) channels. The role of Ca(2+) influx in processes beyond breast cancer cell proliferation and migration should become the focus of studies in the next decade.

Durable remission of renal cell carcinoma in conjuncture with graft versus host disease following allogeneic stem cell transplantation and donor lymphocyte infusion: rule or exception?

Allogeneic stem cell transplantation (alloSCT) followed by donor lymphocyte infusion (DLI) can be applied as immunotherapeutic intervention to treat malignant diseases. Here, we describe a patient with progressive metastatic clear cell renal cell carcinoma (RCC) who was treated with T cell depleted non-myeloablative alloSCT and DLI resulting in disease regression accompanied by extensive graft versus host disease (GVHD). We characterized the specificity of this immune response, and detected a dominant T cell population recognizing a novel minor histocompatibility antigen (MiHA) designated LB-FUCA2-1V. T cells specific for LB-FUCA2-1V were shown to recognize RCC cell lines, supporting a dominant role in the graft versus tumor (GVT) reaction. However, coinciding with the gradual disappearance of chronic GVHD, the anti-tumor effect declined and 3 years after alloSCT the metastases became progressive again. To re-initiate the GVT reaction, escalating doses of DLI were given, but no immune response could be induced and the patient died of progressive disease 8.5 years after alloSCT. Gene expression studies illustrated that only a minimal number of genes shared expression between RCC and professional antigen presenting cells but were not expressed by non-malignant healthy tissues, indicating that in patients suffering from RCC, GVT reactivity after alloSCT may be unavoidably linked to GVHD.

Allogeneic stem cell transplantation for renal cell carcinoma

Allogeneic hematopoietic stem cell transplantation from a compatible donor has been utilized as adoptive immunotherapy in metastatic, cytokine-refractory renal cell carcinoma (RCC). Since the year 2000, several investigators have established that RCC is susceptible to a graft-versus-tumor effect: they reported that patients with renal cancer may have partial or complete disease responses, in the 20-40% range, after allogeneic transplantation following a reduced-intensity regimen. However, transplant-related mortality is still high in the 10-20% range, and responses are rarely durable. Experimental evidence suggests that donor-derived T cells and natural killer cells are the main mediators of the graft-versus-RCC effect upon allogeneic hematopoietic stem-cell transplantation. Isolation of CD8(+) cytotoxic T lymphocyte clones recognizing several target antigens of graft-versus-RCC effect (minor histocompatibility antigens on RCC cells; a peptide epitope derived from human endogenous retrovirus type E; the tumor-associated antigen encoded by the Wilms' tumor 1 gene) has increased our knowledge of the disease and has opened up the possibility of antigen-specific adoptive cell therapy. The introduction in the clinic of molecularly targeted agents that interfere with neoangiogenesis, both monoclonal antibodies and small tyrosine-kinase inhibitor molecules (e.g., sunitinib, sorafenib and bevacizumab), has decreased the use of allogeneic transplantation. Although not curative, novel targeted agents may be combined with allogeneic transplantation or with adoptive cell therapy in order to maximize the chances of cure.

A polymorphism in the splice donor site of ZNF419 results in the novel renal cell carcinoma-associated minor histocompatibility antigen ZAPHIR

Nonmyeloablative allogeneic stem cell transplantation (SCT) can induce remission in patients with renal cell carcinoma (RCC), but this graft-versus-tumor (GVT) effect is often accompanied by graft-versus-host disease (GVHD). Here, we evaluated minor histocompatibility antigen (MiHA)-specific T cell responses in two patients with metastatic RCC who were treated with reduced-intensity conditioning SCT followed by donor lymphocyte infusion (DLI). One patient had stable disease and emergence of SMCY.A2-specific CD8+ T cells was observed after DLI with the potential of targeting SMCY-expressing RCC tumor cells. The second patient experienced partial regression of lung metastases from whom we isolated a MiHA-specific CTL clone with the capability of targeting RCC cell lines. Whole genome association scanning revealed that this CTL recognizes a novel HLA-B7-restricted MiHA, designated ZAPHIR, resulting from a polymorphism in the splice donor site of the ZNF419 gene. Tetramer analysis showed that emergence of ZAPHIR-specific CD8+ T cells in peripheral blood occurred in the absence of GVHD. Furthermore, the expression of ZAPHIR in solid tumor cell lines indicates the involvement of ZAPHIR-specific CD8+ T cell responses in selective GVT immunity. These findings illustrate that the ZNF419-encoded MiHA ZAPHIR is an attractive target for specific immunotherapy after allogeneic SCT.

PD-1/PD-L1 interactions contribute to functional T-cell impairment in patients who relapse with cancer after allogeneic stem cell transplantation

Tumor relapses remain a serious problem after allogeneic stem cell transplantation (alloSCT), despite the long-term persistence of minor histocompatibility antigen (MiHA)-specific memory CD8(+) T cells specific for the tumor. We hypothesized that these memory T cells may lose their function over time in transplanted patients. Here, we offer functional and mechanistic support for this hypothesis, based on immune inhibition by programmed death-1 (PD-1) expressed on MiHA-specific CD8(+) T cells and the associated role of the PD-1 ligand PD-L1 on myeloid leukemia cells, especially under inflammatory conditions. PD-L1 was highly upregulated on immature human leukemic progenitor cells, whereas costimulatory molecules such as CD80 and CD86 were not expressed. Thus, immature leukemic progenitor cells seemed to evade the immune system by inhibiting T-cell function via the PD-1/PD-L1 pathway. Blocking PD-1 signaling using human antibodies led to elevated proliferation and IFN-γ production of MiHA-specific T cells cocultured with PD-L1-expressing leukemia cells. Moreover, patients with relapsed leukemia after initial MiHA-specific T-cell responses displayed high PD-L1 expression on CD34(+) leukemia cells and increased PD-1 levels on MiHA-specific CD8(+) T cells. Importantly, blocking PD-1/PD-L1 interactions augment proliferation of MiHA-specific CD8(+) memory T cells from relapsed patients. Taken together, our findings indicate that the PD-1/PD-L pathway can be hijacked as an immune escape mechanism in hematological malignancies. Furthermore, they suggest that blocking the PD-1 immune checkpoint offers an appealing immunotherapeutic strategy following alloSCT in patients with recurrent or relapsed disease.

Allogeneic hematopoietic cell transplantation for renal cell carcinoma: ten years after

INTRODUCTION

The first series of patients with metastatic renal cell carcinoma (RCC) treated by non-myeloablative allogeneic hematopoietic cell transplantation (HCT) was reported in 2000 and demonstrated an allogeneic graft-versus-tumor (GVT) effect that encouraged further investigation of this approach. However, the past 10 years have also witnessed profound changes in the medical management of metastatic RCC with the introduction of targeted therapies directed against VEGF or mammalian target of rapamycin (mTOR) signaling pathways creating uncertainty about a continued role for allogeneic HCT in the treatment of RCC.

AREAS COVERED

A total of 21 published reports describing clinical outcomes for 398 patients with metastatic RCC treated by allogeneic HCT compiled herein provide a composite overview of the world wide experience for key efficacy and toxicity outcomes. Review of correlative studies that identify donor-derived T cells as mediators of RCC-specific GVT effects offers insight into both the potential as well as the technical barriers to the delivery of antigen-specific post-transplant cellular therapy or vaccination designed to augment the allogeneic GVT effect.

EXPERT OPINION

The future development of non-myeloablative allogeneic HCT for metastatic RCC will require novel treatment protocols designed to augment and sustain post-transplant GVT effects against RCC to generate renewed enthusiasm for this approach.

siRNA silencing of PD-L1 and PD-L2 on dendritic cells augments expansion and function of minor histocompatibility antigen-specific CD8+ T cells

Tumor relapse after human leukocyte antigen-matched allogeneic stem cell transplantation (SCT) remains a serious problem, despite the long-term presence of minor histocompatibility antigen (MiHA)-specific memory T cells. Dendritic cell (DC)-based vaccination boosting MiHA-specific T-cell immunity is an appealing strategy to prevent or counteract tumor recurrence, but improvement is necessary to increase the clinical benefit. Here, we investigated whether knockdown of programmed death ligand 1 (PD-L1) and PD-L2 on monocyte-derived DCs results in improved T-cell activation. Electroporation of single siRNA sequences into immature DCs resulted in efficient, specific, and long-lasting knockdown of PD-L1 and PD-L2 expression. PD-L knockdown DCs strongly augmented interferon-γ and interleukin-2 production by stimulated T cells in an allogeneic mixed lymphocyte reaction, whereas no effect was observed on T-cell proliferation. Moreover, we demonstrated that PD-L gene silencing, especially combined PD-L1 and PD-L2 knockdown, resulted in improved proliferation and cytokine production of keyhole limpet hemocyanin-specific CD4(+) T cells. Most importantly, PD-L knockdown DCs showed superior potential to expand MiHA-specific CD8(+) effector and memory T cells from leukemia patients early after donor lymphocyte infusion and later during relapse. These data demonstrate that PD-L siRNA electroporated DCs are highly effective in enhancing T-cell proliferation and cytokine production, and are therefore attractive cells for improving the efficacy of DC vaccines in cancer patients.

Myeloid leukemic progenitor cells can be specifically targeted by minor histocompatibility antigen LRH-1–reactive cytotoxic T cells

CD8+ T cells recognizing minor histocompatibility antigens (MiHAs) on leukemic stem and progenitor cells play a pivotal role in effective graft-versus-leukemia reactivity after allogeneic stem cell transplantation (SCT). Previously, we identified a hematopoiesis-restricted MiHA, designated LRH-1, which is presented by HLA-B7 and encoded by the P2X5 purinergic receptor gene. We found that P2X5 is significantly expressed in CD34+ leukemic subpopulations from chronic myeloid leukemia (CML) and acute myeloid leukemia (AML) patients. Here, we demonstrate that LRH-1–specific CD8+ T-cell responses are frequently induced in myeloid leukemia patients following donor lymphocyte infusions. Patients with high percentages of circulating LRH-1–specific CD8+ T cells had no or only mild graft-versus-host disease. Functional analysis showed that LRH-1–specific cytotoxic T lymphocytes (CTLs) isolated from 2 different patients efficiently target LRH-1–positive leukemic CD34+ progenitor cells from both CML and AML patients, whereas mature CML cells are only marginally lysed due to down-regulation of P2X5. Furthermore, we observed that relative resistance to LRH-1 CTL-mediated cell death due to elevated levels of antiapoptotic XIAP could be overcome by IFN-γ prestimulation and increased CTL-target ratios. These findings provide a rationale for use of LRH-1 as immunotherapeutic target antigen to treat residual or persisting myeloid malignancies after allogeneic SCT.