PTEN loss increases PD-L1 protein expression and affects the correlation between PD-L1 expression and clinical parameters in colorectal cancer

Role of renin angiotensin system inhibitors and metformin in Glioblastoma Therapy: a review

Glioblastoma multiforme (GBM) is a highly aggressive and incurable disease accounting for about 10,000 deaths in the USA each year. Despite the current treatment approach which includes surgery with chemotherapy and radiation therapy, there remains a high prevalence of recurrence. Notable improvements have been observed in persons receiving concurrent antihypertensive drugs such as renin angiotensin inhibitors (RAS) or the antidiabetic drug metformin with standard therapy. Anti-tumoral effects of RAS inhibitors and metformin have been observed in in vitro and in vivo studies. Although clinical trials have shown mixed results, the potential for the use of RAS inhibitors and metformin as adjuvant GBM therapy remains promising. Nevertheless, evidence suggest that these drugs exert multimodal antitumor actions; by particularly targeting several cancer hallmarks. In this review, we highlight the results of clinical studies using multidrug cocktails containing RAS inhibitors and or metformin added to standard therapy for GBM. In addition, we highlight the possible molecular mechanisms by which these repurposed drugs with an excellent safety profile might elicit their anti-tumoral effects. RAS inhibition elicits anti-inflammatory, anti-angiogenic, and immune sensitivity effects in GBM. However, metformin promotes anti-migratory, anti-proliferative and pro-apoptotic effects mainly through the activation of AMP-activated protein kinase. Also, we discussed metformin's potential in targeting both GBM cells as well as GBM associated-stem cells. Finally, we summarize a few drug interactions that may cause an additive or antagonistic effect that may lead to adverse effects and influence treatment outcome.

GSG2 promotes progression of human endometrial cancer by regulating PD-1/PD-L1 expression via PI3K-AKT pathway

Cell cycle dysregulation leading to uncontrolled growth is a primary characteristic of malignancy. GSG2, a mitosis-related kinase, affects the normal cell cycle by interfering with the normal dissociation of centromere cohesion, and its overexpression has been shown to play an important role in cancer cells. Here, we investigated the function of GSG2 as a tumor promoter in endometrial carcinoma and its relationship with the immunological microenvironment. We used immunohistochemistry to identify a correlation between the development and prognosis of GSG2 and endometrial cancer. Cell and animal experiments confirmed that GSG2 has a protumorigenic phenotype in endometrial cancer cell lines. Furthermore, using GeneChip analysis and a tumor-immune coculture model, we observed a link between GSG2 expression and the composition of the immune microenvironment. Therefore, we concluded that the activation of the PI3K/AKT pathway by GSG2 may impact DNA repair, disrupt the cell cycle, and regulate the immune response, all of which could increase the ability of EC cells to proliferate malignantly. Consequently, it is anticipated that GSG2 will be a viable therapeutic target in endometrial carcinoma.

Niraparib enhances antitumor immunity and contributes to the efficacy of PD-L1 blockade in cervical cancer

PURPOSE

With the development of immunotherapy research, the role of immune checkpoint blockade (ICB) in the treatment of cervical cancer has been emphasized, but many patients still can't receive long-term benefits from ICB. Poly ADP ribose polymerase inhibitor (PARPi) has been proved to exert significant antitumor effects in multiple solid tumors. Whether cervical cancer patients obtain better benefits from the treatment regimen of PARPi combined with ICB remains unclear.

METHODS

The alteration of PD-L1 expression induced by niraparib in cervical cancer cells and its underlying mechanism were assessed by western blot and immunofluorescence and quantitative real-time polymerase chain reaction (qRT-PCR).The regulation of PTEN by KDM5A was confirmed using Chromatin immunoprecipitation (ChIP) assay and RNA interference. Analyzing the relationship between PD-L1 and immune effector molecules through searching online databases. Therapeutic efficacy of niraparib, PD-L1 blockade or combination was assessed in syngeneic tumor model. The changes of immune cells and cytokines in vivo was detected by immunohistochemistry (IHC) and qRT-PCR.

RESULTS

We found that niraparib upregulated PD-L1 expression and potentiated the antitumor effects of PD-L1 blockade in a murine cervical cancer model. Niraparib inhibited the Pten expression by increasing the abundance of KDM5A, which expanded PD-L1 abundance through activating the PI3K-AKT-S6K1 pathway. PD-L1 was positively correlated with immune effector molecules including TNF-α, IFN-γ, granzyme A and granzyme B based on biological information analysis. Niraparib increased the infiltration of CD8+ T cells and the level of IFN-γ, granzyme B in vivo.

CONCLUSION

Our findings demonstrates the regulation of niraparib on local immune microenvironment of cervical cancer, and provides theoretical basis for supporting the combination of PARPi and PD-L1 blockade as a potential treatment for cervical cancer.

Integrating the PD-L1 Prognostic Biomarker in Non-Muscle Invasive Bladder Cancer in Clinical Practice-A Comprehensive Review on State-of-the-Art Advances and Critical Issues

Bladder cancer (BC) is one of the most prevalent cancers worldwide. Non-muscle invasive bladder cancer (NMIBC), comprising the majority of initial BC presentations, requires accurate risk stratification for optimal management. This review explores the evolving role of programmed cell death ligand 1 (PD-L1) as a prognostic biomarker in NMIBC, with a particular focus on its implications in the context of Bacillus Calmette-Guérin (BCG) immunotherapy. The literature suggests a potential association between elevated PD-L1 status and adverse outcomes, resistance to BCG treatment, and disease progression. However, conflicting findings and methodological issues highlight the heterogeneity of PD-L1 assessment in NMIBC, probably due to the complex biological mechanisms that regulate the interaction between PD-L1 and the tumor microenvironment. The identification of PD-L1 as a prognostic biomarker provides ground for tailored therapeutic interventions, including immune checkpoint inhibitors (ICIs). Nevertheless, challenges such as intratumoral heterogeneity and technical issues underscore the need for standardized protocols and larger, homogeneous trials. This review contributes to the ongoing debate on the personalized management of NMIBC patients, focusing on the advances and perspectives of incorporating PD-L1 as a biomarker in this setting.

Overcoming cold tumors: a combination strategy of immune checkpoint inhibitors

Immune Checkpoint Inhibitors (ICIs) therapy has advanced significantly in treating malignant tumors, though most 'cold' tumors show no response. This resistance mainly arises from the varied immune evasion mechanisms. Hence, understanding the transformation from 'cold' to 'hot' tumors is essential in developing effective cancer treatments. Furthermore, tumor immune profiling is critical, requiring a range of diagnostic techniques and biomarkers for evaluation. The success of immunotherapy relies on T cells' ability to recognize and eliminate tumor cells. In 'cold' tumors, the absence of T cell infiltration leads to the ineffectiveness of ICI therapy. Addressing these challenges, especially the impairment in T cell activation and homing, is crucial to enhance ICI therapy's efficacy. Concurrently, strategies to convert 'cold' tumors into 'hot' ones, including boosting T cell infiltration and adoptive therapies such as T cell-recruiting bispecific antibodies and Chimeric Antigen Receptor (CAR) T cells, are under extensive exploration. Thus, identifying key factors that impact tumor T cell infiltration is vital for creating effective treatments targeting 'cold' tumors.

PTEN loss in glioma cell lines leads to increased extracellular vesicles biogenesis and PD-L1 cargo in a PI3K-dependent manner

Phosphatase and Tensin Homologue (PTEN) is one of the most frequently lost tumor suppressors in cancer and the predominant negative regulator of the PI3K/AKT signaling axis. A growing body of evidence has highlighted the loss of PTEN with immuno-modulatory functions including the upregulation of the programmed death ligand-1 (PD-L1), an altered tumor derived secretome that drives an immunosuppressive tumor immune microenvironment (TIME), and resistance to certain immunotherapies. Given their roles in immunosuppression and tumor growth, we examined whether the loss of PTEN would impact the biogenesis, cargo, and function of extracellular vesicles (EVs) in the context of the anti-tumor associated cytokine interferon-γ (IFN-γ). Through genetic and pharmacological approaches, we show that PD-L1 expression is regulated by JAK/STAT signaling, not PI3K signaling. Instead, we observe that PTEN loss positively upregulates cell surface levels of PD-L1 and enhances the biogenesis of EVs enriched with PD-L1 in a PI3K-dependent manner. We demonstrate that because of these changes, EVs derived from glioma cells lacking PTEN have a greater ability to suppress T cell receptor (TCR) signaling. Taken together, these findings provide important new insights into how the loss of PTEN can contribute to an immunosuppressive TIME, facilitate immune evasion, and highlight a novel role for PI3K signaling in the regulation of EV biogenesis and the cargo they contain.

Expression of PD-L1 and p-RPS6 in epithelial dysplasia and squamous cell carcinoma of the oral cavity

Introduction

Oral squamous cell carcinoma (OSCC) is often preceded by oral epithelial dysplasia (OED). The role of ribosomal protein S6 (RPS6) and programmed cell death ligand-1 (PD-L1) in the progression of OED to OSCC remains unclear. This study aimed to investigate the expression of phosphorylated RPS6 (p-RPS6) and PD-L1 in OSCC and OED and to examine its relationship with clinicopathological features.

Methods

Fifty-two OSCC and 48 OED cases were recruited for immunohistochemical analysis of p-RPS6 and PD-L1 expression. The expression of markers was correlated with clinicopathological features of OSCC and OED.

Results

We found p-RPS6 expression in all cases of OSCC and OED, whereas PD-L1 was expressed in 42/48 (87%) OED and in 28/52 (53%) OSCC. The patients with mild OED presented higher expression level of PD-L1 and p-RPS6 significantly, when compared to moderate-differentiated OSCC patients (p < 0.05). Moreover, we found a significant positive correlation between PD-L1 and p-RPS6 expression in OED and OSCC patients (p < 0.01). The PD-L1 expression was significantly related to more than 2 cm tumor size in OSCC patients (p = 0.007).

Discussion

Our findings suggest the upregulation of PD-L1 may be related with activation of the mTOR pathway in the early events of tumor progression and the pathogenesis of OSCC.

The Clinicopathological Correlation of KRAS Mutation and PTEN Expression Status in Primary and Metastatic Colorectal Carcinoma

BACKGROUND

Colorectal cancer (CRC) research has identified a consistent loss of PTEN expression in both primary tumors and metastasis, highlighting its potential role in this disease. However, the impact of PTEN on downstream proteins of KRAS mutation, namely p-AKT, p-ERK, and p65 (NFkB), remains unknown. This study aims to explore the inhibitory effect of PTEN on KRAS downstream proteins and its correlation with pathological features in CRC patients.

METHODS

From January 1, 2015, to December 31, 2021, 86 CRC cases were collected from governmental and private laboratories in the Duhok province. Formalin-fixed, paraffin-embedded tissue blocks were obtained, and the study involved histopathological analysis, immunohistochemistry of PTEN, AKT, ERK, and P65 markers, and molecular analysis of the KRAS gene.

RESULTS

Among the 86 cases, there were 46 males (53.5%) and 40 females (46.5%), with an equal distribution between right colon and left colon/rectum. Tumors larger than 5cm were observed in 47 cases, predominantly displaying a polypoid or ulcerated growth pattern. Most cases were moderately differentiated adenocarcinomas, with stages II and III being the most prevalent 31 cases (36%) and 34 cases (39.5%) respectively. Significant associations were found between PTEN, ERK expressions, and tumor location in the right colon (P=0.031 and P=0.009 respectively). Tumor size correlated with P65 expression (P=0.042). KRAS mutation showed a positive relationship with the type of tumor growth (P=0.035). Tumor grade increased with KRAS mutations (P=0.043). PTEN expression correlated significantly with ERK and AKT markers (P=0.018 and 0.035 respectively). P65 exhibited an association with KRAS mutation (P=0.034).

CONCLUSION

The study revealed PTEN expression in association with the inhibition of AKT and ERK, and the absence of KRAS gene mutation. Conversely, PTEN is not expressed with the positively reactive P65 and the presence of KRAS mutation. This study contributes valuable insights into the complex interplay between PTEN expression, KRAS mutation, and downstream signaling pathways in CRC. It suggests potential avenues for further research and therapeutic strategies in the context of CRC treatment.

Role of stromal PD-L1 expression in colorectal liver metastasis

BACKGROUND AND AIM

The outcomes of immune checkpoint blockade for colorectal cancer (CRC) treatment are unsatisfactory. Furthermore, the efficacy of immune checkpoint blockade for liver metastasis of various cancer is poor. Here, we investigated the relationship between stromal programmed death-ligand 1 (PD-L1) expression and the prognosis of patients with colorectal cancer liver metastasis (CRLM).

METHODS

The present study enrolled 84 CRLM patients who underwent surgery (R0) for CRC. Immunohistochemistry was performed to analyze stromal PD-L1 expression in CRLM.

RESULTS

Stromal PD-L1 was expressed in 52.3% of CRLM samples, which was associated with fewer not optimally resectable metastases (p = 0.04). Stromal PD-L1 also tended to associate with a lower tumor grade (p = 0.08). Stromal PD-L1-positive patients had longer overall survival (p = 0.003). Multivariate analysis identified stromal PD-L1 expression (p = 0.008) and poorer differentiation (p < 0.001) as independent prognostic indicators. Furthermore, stromal PD-L1 expression was correlated to a high number of tumor-infiltrating lymphocytes (TILs). Stromal PD-L1- and low TIL groups had shorter OS than stromal PD-L1 + and high TIL groups (46.6% vs. 81.8%, p = 0.05) Stromal PD-L1-positive patients had longer disease-free survival (DFS) (p = 0.03) and time to surgical failure (p = 0.001). Interestingly, stromal PD-L1 expression was positively related to the desmoplastic subtype (p = 0.0002) and inversely related to the replacement subtype of the histological growth pattern (p = 0.008).

CONCLUSIONS

Stromal PD-L1 expression may be a significant prognostic marker for CRLM.

PROGNOSTIC IMPLICATIONS OF PD-L1 EXPRESSION AND LOSS OF PTEN IN PATIENTS WITH RHABDOMYOSARCOMA, EWING'S SARCOMA AND OSTEOSARCOMA

BACKGROUND

In children, osteosarcoma (OS), Ewing's sarcoma (ES), and rhabdomyosarcoma (RMS) are the most common sarcomas. A link between the anti-programmed death ligand-1 PD-L1 and the tumor suppressor phosphatase and tensin homologue (PTEN) expression has been described in many tumors. The aim of this work is to determine clinicopathological relationships and the possible prognostic significance of PD-L1 and PTEN expression in rhabdomyosarcoma (RMS), Ewing's sarcoma (ES), and osteosarcoma (OS).

MATERIALS AND METHODS

Expression of PD-L1 and PTEN were examined by immunohistochemistry in 45 archival RMS, ES, and OS cases.

RESULTS

The positive expression of PD-L1 was found in 16.7% and 31.6% of ES and OS, respectively. The negative PD-L1 was related to a substantially longer survival in ES cases (p = 0.045), but positive PD-L1 expression was significantly associated with the increased tumor stage and vascular invasion in the OS cases (p = 0.005 and p = 0.002), respectively. On the other hand, PTEN loss was strongly associated with deep tumor, high tumor grade, and recurrence in RMS (p = 0.002, p = 0.045, and p = 0.026, respectively). However, PTEN loss was significantly absent in ES as tumor grade increased (p = 0.031). It is noteworthy that tumor recurrence, the loss of PTEN, and positive PD-L1 were all considered predictive factors in OS patients (p = 0.045, p = 0.032, and p = 0.02, respectively).

CONCLUSIONS

In children, OS and ES have positive PD-L1 expression, which has an independent unfavorable prognostic effect and raises the possibility of using PD-L1 as a therapeutic target. OS, ES, and RMS prognosis are all predicted by PTEN loss.

PD-L1 and AKT Overexpressing Adipose-Derived Mesenchymal Stem Cells Enhance Myocardial Protection by Upregulating CD25+ T Cells in Acute Myocardial Infarction Rat Model

This study explores the synergistic impact of Programmed Death Ligand 1 (PD-L1) and Protein Kinase B (Akt) overexpression in adipose-derived mesenchymal stem cells (AdMSCs) for ameliorating cardiac dysfunction after myocardial infarction (MI). Post-MI adult Wistar rats were allocated into four groups: sham, MI, ADMSC treatment, and ADMSCs overexpressed with PD-L1 and Akt (AdMSC-PDL1-Akt) treatment. MI was induced via left anterior descending coronary artery ligation, followed by intramyocardial AdMSC injections. Over four weeks, cardiac functionality and structural integrity were assessed using pressure-volume analysis, infarct size measurement, and immunohistochemistry. AdMSC-PDL1-Akt exhibited enhanced resistance to reactive oxygen species (ROS) in vitro and ameliorated MI-induced contractile dysfunction in vivo by improving the end-systolic pressure-volume relationship and preload-recruitable stroke work, together with attenuating infarct size. Molecular analyses revealed substantial mitigation in caspase3 and nuclear factor-κB upregulation in MI hearts within the AdMSC-PDL1-Akt group. Mechanistically, AdMSC-PDL1-Akt fostered the differentiation of normal T cells into CD25+ regulatory T cells in vitro, aligning with in vivo upregulation of CD25 in AdMSC-PDL1-Akt-treated rats. Collectively, PD-L1 and Akt overexpression in AdMSCs bolsters resistance to ROS-mediated apoptosis in vitro and enhances myocardial protective efficacy against MI-induced dysfunction, potentially via T-cell modulation, underscoring a promising therapeutic strategy for myocardial ischemic injuries.

Clinicopathological and prognostic significance of PD-L1 expression in colon adenocarcinoma tumor budding

OBJECTIVE

In this study, we investigated the relationship between programmed cell death ligand 1 (PD-L1) and programmed cell death protein 1 (PD-1) expression in colon adenocarcinoma tumor budding.

METHODS

This study included 122 patients with colon adenocarcinomas. The largest sample of formaldehyde-fixed paraffin-embedded tumor tissues was selected for analysis. Expression of membranous PD-L1 (clone 22C3) and the Combined Positive Score (CPS) in tumor tissues was calculated and graded according to the percentages of peritumoral and intratumoral tumor cells (0 %, 1 %, 1-5 %, >5 %). The effects of these factors on the prognosis were analyzed.

RESULTS

Tumor budding was associated with adverse clinicopathological features and poor overall survival. PD-L1 (CPS%) peritumoral tumor budding (1 %/<1 %) was statistically significant in the univariate model (p = 0.004). Age, organ metastases (liver, lung, liver, lung, and peritoneum), and metastases were statistically significant in the multivariate model (p = 0.001, p = 0.004, p = 0.001, p = 0.002, p = 0.004, and p = 0.032, respectively). PD-L1 positive staining was mostly observed around the tumor and during tumor budding. PD-L1 peritumoral tumor budding rates and patients' survival rates differed significantly (log-rank = 12.07, p = 0.007).

CONCLUSION

We found that patients with PD-L1 (CPS%) > 1 % in tumor budding had a shortened life expectancy and demonstrated the importance of including tumor budding areas in the samples used for biomarker evaluation. We previously reported that PD-L1 expression in tumor budding is associated with more aggressive cancer biology and poor survival, although overall survival is of limited statistical significance.

Opaganib (ABC294640) Induces Immunogenic Tumor Cell Death and Enhances Checkpoint Antibody Therapy

Antibody-based cancer drugs that target the checkpoint proteins CTLA-4, PD-1 and PD-L1 provide marked improvement in some patients with deadly diseases such as lung cancer and melanoma. However, most patients are either unresponsive or relapse following an initial response, underscoring the need for further improvement in immunotherapy. Certain drugs induce immunogenic cell death (ICD) in tumor cells in which the dying cells promote immunologic responses in the host that may enhance the in vivo activity of checkpoint antibodies. Sphingolipid metabolism is a key pathway in cancer biology, in which ceramides and sphingosine 1-phosphate (S1P) regulate tumor cell death, proliferation and drug resistance, as well as host inflammation and immunity. In particular, sphingosine kinases are key sites for manipulation of the ceramide/S1P balance that regulates tumor cell proliferation and sensitivity to radiation and chemotherapy. We and others have demonstrated that inhibition of sphingosine kinase-2 by the small-molecule investigational drug opaganib (formerly ABC294640) kills tumor cells and increases their sensitivities to other drugs and radiation. Because sphingolipids have been shown to regulate ICD, opaganib may induce ICD and improve the efficacy of checkpoint antibodies for cancer therapy. This was demonstrated by showing that in vitro treatment with opaganib increases the surface expression of the ICD marker calreticulin on a variety of tumor cell types. In vivo confirmation was achieved using the gold standard immunization assay in which B16 melanoma, Lewis lung carcinoma (LLC) or Neuro-2a neuroblastoma cells were treated with opaganib in vitro and then injected subcutaneously into syngeneic mice, followed by implantation of untreated tumor cells 7 days later. In all cases, immunization with opaganib-treated cells strongly suppressed the growth of subsequently injected tumor cells. Interestingly, opaganib treatment induced crossover immunity in that opaganib-treated B16 cells suppressed the growth of both untreated B16 and LLC cells and opaganib-treated LLC cells inhibited the growth of both untreated LLC and B16 cells. Next, the effects of opaganib in combination with a checkpoint antibody on tumor growth in vivo were assessed. Opaganib and anti-PD-1 antibody each slowed the growth of B16 tumors and improved mouse survival, while the combination of opaganib plus anti-PD-1 strongly suppressed tumor growth and improved survival (p < 0.0001). Individually, opaganib and anti-CTLA-4 antibody had modest effects on the growth of LLC tumors and mouse survival, whereas the combination of opaganib with anti-CTLA-4 substantially inhibited tumor growth and increased survival (p < 0.001). Finally, the survival of mice bearing B16 tumors was only marginally improved by opaganib or anti-PD-L1 antibody alone but was nearly doubled by the drugs in combination (p < 0.005). Overall, these studies demonstrate the ability of opaganib to induce ICD in tumor cells, which improves the antitumor activity of checkpoint antibodies.

Correlation between KRAS Mutation and CTLA-4 mRNA Expression in Circulating Tumour Cells: Clinical Implications in Colorectal Cancer

Combination strategies of KRAS inhibition with immunotherapy in treating advanced or recurrent colorectal carcinoma (CRC) may need to be assessed in circulating tumour cells (CTCs) to achieve better clinical outcomes. This study aimed to investigate the genomic variations of KRAS in CTCs and matched CRC tissues and compared mRNA expression of KRAS and CTLA-4 between wild-type and KRAS-mutated CTCs and CRC tissues. Clinicopathological correlations were also compared. Six known mutations of KRAS were identified at both codon 12 and codon 13 (c.35G>T/G12V, c.35G>A7/G12D, c.35G>C/G12A, c.34G>A/G12S, c.38G>C/G13A, and c.38G>A/G13D). Three CTC samples harboured the identified mutations (16.7%; 3/18), while fifteen matched primary tumour tissues (65.2%, 15/23) showed the mutations. CTCs harbouring the KRAS variant were different from matched CRC tissue. All the mutations were heterozygous. Though insignificant, CTLA-4 mRNA expression was higher in patients carrying KRAS mutations. Patients harbouring KRAS mutations in CTCs were more likely to have poorly differentiated tumours (p = 0.039) and with lymph node metastasis (p = 0.027) and perineural invasion (p = 0.014). KRAS mutations in CTCs were also significantly correlated with overall pathological stages (p = 0.027). These findings imply the genetic basis of KRAS with immunotherapeutic target molecules based on a real-time platform. This study also suggests the highly heterogeneous nature of cancer cells, which may facilitate the assessment of clonal dynamics across a single patient's disease.

PI3K/AKT/mTOR signaling transduction pathway and targeted therapies in cancer

The PI3K/AKT/mTOR (PAM) signaling pathway is a highly conserved signal transduction network in eukaryotic cells that promotes cell survival, cell growth, and cell cycle progression. Growth factor signalling to transcription factors in the PAM axis is highly regulated by multiple cross-interactions with several other signaling pathways, and dysregulation of signal transduction can predispose to cancer development. The PAM axis is the most frequently activated signaling pathway in human cancer and is often implicated in resistance to anticancer therapies. Dysfunction of components of this pathway such as hyperactivity of PI3K, loss of function of PTEN, and gain-of-function of AKT, are notorious drivers of treatment resistance and disease progression in cancer. In this review we highlight the major dysregulations in the PAM signaling pathway in cancer, and discuss the results of PI3K, AKT and mTOR inhibitors as monotherapy and in co-administation with other antineoplastic agents in clinical trials as a strategy for overcoming treatment resistance. Finally, the major mechanisms of resistance to PAM signaling targeted therapies, including PAM signaling in immunology and immunotherapies are also discussed.

The Role of Pathogenesis Associated with the Tumor Microclimate in the Differential Diagnosis of Uterine Myocytic Tumors

Myocytic tumors of the uterus present vast morphological heterogeneity, which makes differential diagnosis between the different entities necessary. This study aims to enrich the existing data and highlight new potential therapeutic targets regarding aspects related to the pathogenic process and the tumor microenvironment in order to improve the quality of life of women. We performed a 5-year retrospective study, including particular cases of uterine myocyte tumors. Immunohistochemical analyses of pathogenic pathways (p53, RB1, and PTEN) and tumor microclimate using markers (CD8, PD-L1, and CD105), as well as genetic testing of the PTEN gene, were performed. The data were statistically analyzed using the appropriate parameters. In cases of atypical leiomyoma, a significant association was observed between PTEN deletion and an increased number of PD-L1+ T lymphocytes. For malignant lesions and STUMP, PTEN deletion was associated with the advanced disease stage. Advanced cases were also associated with an increased mean CD8+ T cell count. An increased number of lymphocytes was associated with an increased percentage of RB1+ nuclei. The study corroborated clinical and histogenetic data, highlighting the importance of the differential diagnosis of these tumors to improve the management of patients and increase their quality of life.

Immune Resistance Mechanisms and the Road to Personalized Immunotherapy

What does the future of cancer immunotherapy look like and how do we get there? Find out where we've been and where we're headed in A Report on Resistance: The Road to personalized immunotherapy.

Copper in cancer: From pathogenesis to therapy

One of the basic trace elements for the structure and metabolism of human tissue is copper. However, as a heavy metal, excessive intake or abnormal accumulation of copper in the body can cause inevitable damage to the organism because copper can result in direct injury to various cell components or disruption of the redox balance, eventually leading to cell death. Interestingly, a growing body of research reports that diverse cancers have raised serum and tumor copper levels. Tumor cells depend on more copper for their metabolism than normal cells, and a decrease in copper or copper overload can have a detrimental effect on tumor cells. New modalities for identifying and characterizing copper-dependent signals offer translational opportunities for tumor therapy, but their mechanisms remain unclear. Therefore, this article summarizes what we currently know about the correlation between copper and cancer and describes the characteristics of copper metabolism in tumor cells and the prospective application of copper-derived therapeutics.

Pan-cancer genomic analysis shows hemizygous PTEN loss tumors are associated with immune evasion and poor outcome

In tumors, somatic mutations of the PTEN suppressor gene are associated with advanced disease, chemotherapy resistance, and poor survival. PTEN loss of function may occur by inactivating mutation, by deletion, either affecting one copy (hemizygous loss) leading to reduced gene expression or loss of both copies (homozygous) with expression absent. Various murine models have shown that minor reductions in PTEN protein levels strongly influence tumorigenesis. Most PTEN biomarker assays dichotomize PTEN (i.e. presence vs. absence) ignoring the role of one copy loss. We performed a PTEN copy number analysis of 9793 TCGA cases from 30 different tumor types. There were 419 (4.28%) homozygous and 2484 (25.37%) hemizygous PTEN losses. Hemizygous deletions led to reduced PTEN gene expression, accompanied by increased levels of instability and aneuploidy across tumor genomes. Outcome analysis of the pan-cancer cohort showed that losing one copy of PTEN reduced survival to comparable levels as complete loss, and was associated with transcriptomic changes controlling immune response and the tumor microenvironment. Immune cell abundances were significantly altered for PTEN loss, with changes in head and neck, cervix, stomach, prostate, brain, and colon more evident in hemizygous loss tumors. These data suggest that reduced expression of PTEN in tumors with hemizygous loss leads to tumor progression and influences anticancer immune response pathways.

Diagnostic Predictors of Immunotherapy Response in Head and Neck Squamous Cell Carcinoma

Programmed cell death ligand-1 (PD-L1) binds PD-1 on CD⁸⁺ lymphocytes, inhibiting their cytotoxic action. Its aberrant expression by head and neck squamous cell carcinoma (HNSCC) cells leads to immune escape. Pembrolizumab and nivolumab, two humanized monoclonal antibodies against PD-1, have been approved in HNSCC treatment, but ~60% of patients with recurrent or metastatic HNSCC fail to respond to immunotherapy and only 20 to 30% of treated patients have long-term benefits. The purpose of this review is to analyze all the fragmentary evidence present in the literature to identify what future diagnostic markers could be useful for predicting, together with PD-L1 CPS, the response to immunotherapy and its durability. We searched PubMed, Embase, and the Cochrane Register of Controlled Trials and we summarize the evidence collected in this review. We confirmed that PD-L1 CPS is a predictor of response to immunotherapy, but it should be measured across multiple biopsies and repeatedly over time. PD-L2, IFN-γ, EGFR, VEGF, TGF-β, TMB, blood TMB, CD73, TILs, alternative splicing, tumor microenvironment, and some macroscopic and radiological features are promising predictors worthy of further studies. Studies comparing predictors appear to give greater potency to TMB and CXCR9.

Therapeutic Implications of the Drug Resistance Conferred by Extracellular Vesicles Derived from Triple-Negative Breast Cancer Cells

Anticancer drug resistance is a significant impediment in current cancer treatment. Extracellular vesicles (EVs) derived from cancer cells were recently acknowledged as a critical mechanism of drug resistance, tumor progression, and metastasis. EVs are enveloped vesicles comprising a lipid bilayer that transfers various cargo, including proteins, nucleic acids, lipids, and metabolites, from an originating cell to a recipient cell. Investigating the mechanisms whereby EVs confer drug resistance is still in the early stages. In this review, I analyze the roles of EVs derived from triple-negative breast cancer cells (TNBC-EVs) in anticancer drug resistance and discuss strategies to overcome TNBC-EV-mediated drug resistance.

Current State and Future Challenges for PI3K Inhibitors in Cancer Therapy

The phosphoinositide 3 kinase (PI3K)-protein kinase B (PKB/AKT)-mammalian target of the rapamycin (mTOR) axis is a key signal transduction system that links oncogenes and multiple receptor classes which are involved in many essential cellular functions. Aberrant PI3K signalling is one of the most commonly mutated pathways in cancer. Consequently, more than 40 compounds targeting key components of this signalling network have been tested in clinical trials among various types of cancer. As the oncogenic activation of the PI3K/AKT/mTOR pathway often occurs alongside mutations in other signalling networks, combination therapy should be considered. In this review, we highlight recent advances in the knowledge of the PI3K pathway and discuss the current state and future challenges of targeting this pathway in clinical practice.

PD-L1 is highly expressed in ovarian cancer and associated with cancer stem cells populations expressing CD44 and other stem cell markers

BACKGROUND

Immune checkpoint inhibitors, including PD-L1 (programmed death ligand-1) inhibitors have well documented anticancer therapeutic effect in most types of cancers but its use in the treatment of ovarian cancer is not yet proven. The aim of our study is to explore the predictive biomarkers in ovarian cancer and its association with the outcomes. We have investigated the role of PD-L1 expressions in the tumor microenvironment cells including immune cells and cancer stem cells in different types of ovarian cancer.

METHODS

A total of 119 surgical archived ovarian cancer samples were collected from the pathology department at King Fahad Specialist Hospital, Dammam, Saudi Arabia that included serous carcinomas, clear cell carcinomas, mucinous carcinomas, endometrioid carcinomas, and granulosa cell tumors. Immunohistochemistry (IHC) staining was performed using (i) PD-L1 antibodies to detect PD-L1 expressions; (ii) CD8 and CD4 to detect Tumor Infiltrating Lymphocytes (TILs); and (iii) CD44, LGR5, and ALDH2 to detect stem cell markers. The clinicopathological data were collected from patients' medical record to investigate the association with PD-L1, TILs, and stem cells expressions.

RESULTS

We report high PD-L1 expressions in 47.8% of ovarian cancer samples. PD-L1 expressions were detected in different types of epithelial ovarian cancer and were not associated with poor prognosis of ovarian cancer. However, determining the expression levels of TILs in the ovarian cancer tissues found that 81% (n = 97) of ovarian cancer samples have TILs that express both of CD8 and CD4 and significantly associated with high PD-L1 expressions. Interestingly, we have found that ovarian cancer tissues with high expressions of PD-L1 were associated with high expressions of stem cells expressing CD44 and LGR5.

CONCLUSIONS

PD-L1 is highly expressed in the serous type of ovarian carcinomas and the overall expression of PD-L1 is not associated with poor survival rate. Furthermore, PD-L1 expressions are strongly associated with TILs and stem cell markers in ovarian cancer. Inhibiting the PD-L1 using immune checkpoint inhibitors might downregulate stem cell population that known to be associated with cancer recurrence.

Programmed Cell Death-Ligand 1 in Head and Neck Squamous Cell Carcinoma: Molecular Insights, Preclinical and Clinical Data, and Therapies

Aberrant expression of the programmed cell death protein ligand 1 (PD-L1) constitutes one of the main immune evasion mechanisms of cancer cells. The approval of drugs against the PD-1-PD-L1 axis has given new impetus to the chemo-therapy of many malignancies. We performed a literature review from 1992 to August 2022, summarizing evidence regarding molecular structures, physiological and pathological roles, mechanisms of PD-L1 overexpression, and immunotherapy evasion. Furthermore, we summarized the studies concerning head and neck squamous cell carcinomas (HNSCC) immunotherapy and the prospects for improving the associated outcomes, such as identifying treatment response biomarkers, new pharmacological combinations, and new molecules. PD-L1 overexpression can occur via four mechanisms: genetic modifications; inflammatory signaling; oncogenic pathways; microRNA or protein-level regulation. Four molecular mechanisms of resistance to immunotherapy have been identified: tumor cell adaptation; changes in T-cell function or proliferation; alterations of the tumor microenvironment; alternative immunological checkpoints. Immunotherapy was indeed shown to be superior to traditional chemotherapy in locally advanced/recurrent/metastatic HNSCC treatments.

PD-L1/PD-L1 signalling promotes colorectal cancer cell migration ability through RAS/MEK/ERK

Programmed death ligand 1 (PD-L1) is widely known as an immune checkpoint, and immunotherapy through the inhibition of checkpoint molecules has become an important component in the successful treatment of tumours via programmed death 1 (PD-1)/PD-L1 signalling pathways. However, its biological functions and expression profile in colorectal cancer (CRC) are elusive. We previously found that PD-L1 can bind to PD-L1 and cause cell detachment. However, the detailed molecular mechanisms of how PD-L1 binds to PD-L1 and how it transmits signals to the cell remain unclear. In this study, we disclosed that PD-L1 expression was dramatically upregulated in CRC compared to normal tissues. Ectopic expression of PD-L1 inhibits cell adhesive capacity and promotes cell migration in CRC cell lines, while silencing PD-L1 had the opposite effects and suppressed invasion and proliferation. Mechanistically, PD-L1 was found to promote epithelial-mesenchymal transition (EMT) through the ERK signalling molecule pathway and interacted with the 1-86 aa fragment of KRAS to transduce signals. Collectively, our study demonstrated the role of PD-L1 after binding to PD-L1 in CRC, thereby providing a new theoretical basis for further improving immunotherapy with anti-PD-L1 antibodies.

Pivotal role of PD-1/PD-L1 immune checkpoints in immune escape and cancer progression: Their interplay with platelets and FOXP3+Tregs related molecules, clinical implications and combinational potential with phytochemicals

Immune checkpoint proteins including programmed cell death protein 1 (PD-1), its ligand PD-L1 and cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) are involved in proliferation, angiogenesis, metastasis, chemoresistance via immune escape and immune tolerance by disturbing cytotoxic T cell activation. Though many clinical trials have been completed in several cancers by using immune checkpoint inhibitors alone or in combination with other agents to date, recently multi-target therapy is considered more attractive than monotherapy, since immune checkpoint proteins work with other components such as surrounding blood vessels, dendritic cells, fibroblasts, macrophages, platelets and extracellular matrix within tumor microenvironment. Thus, in the current review, we look back on research history of immune checkpoint proteins and discuss their associations with platelets or tumor cell induced platelet aggregation (TCIPA) and FOXP3+ regulatory T cells (Tregs) related molecules involved in immune evasion and tumor progression, clinical implications of completed trial results and signaling networks by phytochemicals for combination therapy with immune checkpoint inhibitors and suggest future research perspectives.

Clinical implications of the interaction between PD-1/PD-L1 and PI3K/AKT/mTOR pathway in progression and treatment of non-small cell lung cancer

The discovery of immune checkpoints has been well known to provide novel clues for cancer treatments. Immunotherapy against the programmed cell death protein-1 (PD-1) /programmed death-ligand-1 (PD-L1), one of the most popular auxiliary treatments in recent years, has been applied in various tumor treatments, including non-small cell lung cancer (NSCLC). However, inevitable issues such as side effects and drug resistance emerge following the use of immune checkpoint inhibitors. The PI3K/AKT/mTOR pathway may participate in the regulation of PD-L1 expression. Abnormal PI3K/AKT/mTOR pathway activation results in increased PD-L1 protein translation, whereas PD-L1 overexpression can activate the PI3K/AKT/mTOR pathway inversely. Via downstream proteins, including 4E-BP1, STAT3, NF-κB, c-MYC, and AMPK in aberrant energy status, the PI3K/AKT/mTOR pathway can regulate PD-L1 post-transcription and translation. Besides, the regulation of the PI3K pathway by the PD-1/PD-L1 axis involves both tumor cells and the tumor immune microenvironment. Inhibitors targeting the PD-1/PD-L1 have been successfully applied in the treatment of gastrointestinal cancer and breast cancer. Meanwhile, drug resistance from alternative pathway activation also evidently affects clinical progress. To achieve a better therapeutic effect and quality of survival, the combination of multiple treatment modalities presents great research value. Here we reviewed the interaction between PD-1/PD-L1 and PI3K/AKT/mTOR pathway in the progression and treatment of NSCLC and summarized its clinical implications. The intracellular interactions between PD-1/PD-L1 and the PI3K/AKT/mTOR pathway indicate that PD-1/PD-L1 inhibitors have a wide range of potential applications. And we presented the mechanism for combining therapy with monoclonal antibody PD-1/PD-L1 and PI3K/AKT/mTOR inhibitors in this review, to broaden the therapies for NSCLC.

PTEN Expression Was Significantly Associated with PD-L1 Score but Not with EBV Infection in Gastric Cancer

Purpose

Gastric cancer (GC) remains a prevalent aggressive tumor with high morbidity and mortality globally. The identification of GC subtypes based on molecular features improved the prediction of prognosis and the selection of targeted therapies. PTEN is a characteristic tumor suppressor, while its association with different GC subtypes was unknown.

Patients and Methods

The cohort consisted of 248 patients diagnosed with gastric cancer who were hospitalized and received radical gastrectomy. In addition, PTEN gene expression matrix of STAD was retrieved from TCGA. The mRNA and protein levels of PTEN and PD-L1 were detected using qRT-PCR and IHC staining. Multivariate logistic regression and Kaplan–Meier analysis were used to examine the relationship between PTEN expression and clinical characteristics.

Results

In our study, PTEN was downregulated in gastric tumors both in mRNA and protein levels. Its inactivation was closely linked to higher histological grade (P = 0.005), neural invasion (P = 0.012), depth of invasion (P = 0.021), lymph metastasis (P = 0.026), and TNM stage (P = 0.001) of GC in the present study. Moreover, according to the molecular subtypes, high PTEN expression was related to high TPS score of PD-L1 positively (P = 0.010) but was not associated with MSI and EBV infection. Further, TCGA data validated that PTEN was indeed correlated with histological grade and invasion depth and positively related to PD-L1 expression (R = 0.29, adjusted P < 0.001).

Conclusion

The above results suggested that PTEN expression was a useful marker in gastric carcinogenesis and progression and in the selection of immunotherapy-based treatments for GC patients.

Tumor-derived exosomes induce immunosuppressive macrophages to foster intrahepatic cholangiocarcinoma progression

BACKGROUND AND AIMS

Macrophages are prominent components of solid tumors and exhibit distinct functions in different tumor microenvironments. Exosomes are emerging as necessary mediators of the cross-talk between tumor cells and the microenvironment. However, the underlying mechanisms of exosomes involving into crosstalk between tumor cells and macrophages during disease progression of intrahepatic cholangiocarcinoma (ICC) have not been yet fully realized.

APPROACH AND RESULTS

We found that the macrophages of ICC tumor tissues up-regulated the expression levels of immunosuppressive molecule programmed death-ligand 1 (PD-L1). Increased PD-L1⁺ macrophages in tumor tissues effectively suppressed T-cell immunity and correlated with poor survival rates in patients with ICC. High-throughput RNA-sequencing analysis that was performed to identify differential levels of microRNAs (miRNAs) between exosomes derived from ICC cells and primary human intrahepatic biliary epithelial cells revealed that miR-183-5p was increased in ICC cell-derived exosomes. Exosomal miR-183-5p inhibited phosphatase and tensin homolog (PTEN) expression, to subsequently affect the elevations on both phosphorylated AKT and PD-L1 expression in macrophages. Furthermore, macrophages that treated with ICC cell-derived exosomes significantly suppressed T-cell immunity in vitro and contributed to the growth and progression of ICC in vivo, which were reversible through blockages on PD-L1 of these macrophages. Finally, clinical data showed that up-regulated levels of plasma exosomal miR-183-5p correlated with poor prognosis of patients with ICC after curative resection.

CONCLUSIONS

Tumor-derived exosomal miR-183-5p up-regulates PD-L1-expressing macrophages to foster immune suppression and disease progression in ICC through the miR-183-5p/PTEN/AKT/PD-L1 pathway. Exosomal miR-183-5p is a potential predictive biomarker for ICC progression and a potential target for development of therapeutic strategies against immune tolerance feature of ICC.

Thyroid Hormone Induces Oral Cancer Growth via the PD-L1-Dependent Signaling Pathway

Oral cancer is a fatal disease, and its incidence in Taiwan is increasing. Thyroid hormone as L-thyroxine (T₄) stimulates cancer cell proliferation via a receptor on integrin αvβ3 of plasma membranes. It also induces the expression of programmed death-ligand 1 (PD-L1) and cell proliferation in cancer cells. Thyroid hormone also activates β-catenin-dependent cell proliferation in cancer cells. However, the relationship between PD-L1 and cancer proliferation is not fully understood. In the current study, we investigated the role of inducible thyroid hormone-induced PD-L1-regulated gene expression and proliferation in oral cancer cells. Thyroxine bound to integrin αvβ3 to induce PD-L1 expressions via activation of ERK1/2 and signal transducer and activator of transcription 3 (STAT3). Inactivated STAT3 inhibited PD-L1 expression and nuclear PD-L1 accumulation. Inhibition of PD-L1 expression reduced β-catenin accumulation. Furthermore, nuclear PD-L1 formed a complex with nuclear proteins such as p300. Suppression PD-L1 expression by shRNA blocked not only expression of PD-L1 and β-catenin but also signal transduction, proliferative gene expressions, and cancer cell growth. In summary, thyroxine via integrin αvβ3 activated ERK1/2 and STAT3 to stimulate the PD-L1-dependent and β-catenin-related growth in oral cancer cells.

Disrupting the Interplay between Programmed Cell Death Protein 1 and Programmed Death Ligand 1 with Spherical Nucleic Acids in Treating Cancer

Disrupting the interplay between programmed cell death protein 1 (PD-1) and programmed death ligand 1 (PD-L1) is a powerful immunotherapeutic approach to cancer treatment. Herein, spherical nucleic acid (SNA) liposomal nanoparticle conjugates that incorporate a newly designed antisense DNA sequence specifically against PD-L1 (immune checkpoint inhibitor SNAs, or IC-SNAs) are explored as a strategy for blocking PD-1/PD-L1 signaling within the tumor microenvironment (TME). Concentration-dependent PD-L1 silencing with IC-SNAs is observed in MC38 colon cancer cells, where IC-SNAs decrease both surface PD-L1 (sPD-L1) and total PD-L1 expression. Furthermore, peritumoral administration of IC-SNAs in a syngeneic mouse model of MC38 colon cancer leads to reduced sPD-L1 expression in multiple cell populations within the TME, including tumor cells, dendritic cells, and myeloid derived suppressor cells. The treatment effectively increases CD8⁺ T cells accumulation and functionality in the TME, which ultimately inhibits tumor growth and extends animal survival. Taken together, these data show that IC-SNA nanoconstructs are capable of disrupting the PD-1/PD-L1 interplay via gene regulation, thereby providing a promising avenue for cancer immunotherapy.

Transcriptomic Correlates of Tumor Cell PD-L1 Expression and Response to Nivolumab Monotherapy in Metastatic Clear Cell Renal Cell Carcinoma

PURPOSE

PD-L1 expression on tumor cells (TC) is associated with response to anti-PD-1-based therapies in some tumor types, but its significance in clear cell renal cell carcinoma (ccRCC) is uncertain. We leveraged tumor heterogeneity to identify molecular correlates of TC PD-L1 expression in ccRCC and assessed their role in predicting response to anti-PD-1 monotherapy.

EXPERIMENTAL DESIGN

RNA sequencing was performed on paired TC PD-L1 positive and negative areas isolated from eight ccRCC tumors and transcriptomic features associated with PD-L1 status were identified. A cohort of 232 patients with metastatic ccRCC from the randomized CheckMate-025 (CM-025) trial was used to confirm the findings and correlate transcriptomic profiles with clinical outcomes.

RESULTS

In both the paired samples and the CM-025 cohort, TC PD-L1 expression was associated with combined overexpression of immune- and cell proliferation-related pathways, upregulation of T-cell activation signatures, and increased tumor-infiltrating immune cells. In the CM-025 cohort, TC PD-L1 expression was not associated with clinical outcomes. A molecular RCC subtype characterized by combined overexpression of immune- and cell proliferation-related pathways (previously defined by unsupervised clustering of transcriptomic data) was enriched in TC PD-L1 positive tumors and displayed longer progression-free survival (HR, 0.32; 95% confidence interval, 0.13-0.83) and higher objective response rate (30% vs. 0%, P = 0.04) on nivolumab compared with everolimus.

CONCLUSIONS

Both TC-extrinsic (immune-related) and TC-intrinsic (cell proliferation-related) mechanisms are likely intertwined in the regulation of TC PD-L1 expression in ccRCC. The quantitation of these transcriptional programs may better predict benefit from anti-PD-1-based therapy compared with TC PD-L1 expression alone in ccRCC.

Chemoradiation-induced alteration of programmed death-ligand 1, CD8+ tumor-infiltrating lymphocytes and mucin expression in rectal cancer

Introduction: DNA damage and resulting neoantigen formation is considered a mechanism for synergy between radiotherapy and PD-1/PD-L1 pathway inhibition to induce antitumor immune response. We investigated neoadjuvant chemoradiotherapy (nCRT)-induced changes in CD8+ tumor infiltrating lymphocyte, PD-L1 and mucin expression in rectal cancer patients.

Materials and Methods: Tumor samples of rectal adenocarcinoma patients undergoing resection between 2008-2014 with (n = 62) or without (n = 17) nCRT treatment were collected. Sections were stained with CD8 and PD-L1 antibodies for immunohistochemistry. The prevalence of CD8+ cells was recorded in the tumor, interface tumor and background rectal side. Image analysis was used to determine the density of CD8+ lymphocytes. The percentage of PD-L1 expression was manually counted in tumor cells (TC), tumor stroma (TS) and the invasive front (IF). Mucin expression was determined as the percentage of the mucin area in the whole tumor area.

Results: PD-L1 expression on TCs was identified in 7.6% (6/79) of nCRT specimens (p = 0.33) and in none of the non-nCRT patients. Median densities of CD8+ infiltrating T lymphocytes did not differ significantly between the two groups. Mucin expression was significantly higher in the nCRT cohort (p = 0.02). Higher neutrophil to lymphocytes ratio (NLR) after nCRT was associated with worse outcome (HR = 1.04, 95% CI = 1.00–1.08).

Conclusions: nCRT exposure was associated with a non-significant difference in PD-L1 expression in rectal adenocarcinoma patients, possibly due to sample size limitations. Further mechanistic investigations and comprehensive immune analysis are needed to understand nCRT-induced immunologic shift in rectal cancer and to expand the applicability of checkpoint inhibitors in this setting.

Generation, secretion and degradation of cancer immunotherapy target PD-L1

Cancer immunotherapy is a rapidly developing and effective method for the treatment of a variety of malignancies in recent years. As a significant immune checkpoint, programmed cell death 1 ligand 1 (PD-L1) and its receptor programmed cell death protein 1 (PD-1) play the most significant role in cancer immune escape and cancer immunotherapy. Though PD-L1 have become an important target for drug development and there have been various approved drugs and clinic trials targeting it, and various clinical response rate and adverse reactions prevent many patients from benefiting from it. In recent years, combination trials have become the main direction of PD-1/PD-L1 antibodies development. Here, we summarized PD-L1 biofunctions and key roles in various cancers along with the development of PD-L1 inhibitors. The regulators that are involved in controlling PD-L1 expression including post-translational modification, mRNA level regulation as well as degradation and exosome secretory pathway of PD-L1 were focused. This systematic summary may provide comprehensive understanding of different regulations on PD-L1 as well as a broad prospect for the search of the important regulator of PD-L1. The regulatory factors of PD-L1 can be potential targets for immunotherapy and increase strategies of immunotherapy in combination.

A combination of stromal PD-L1 and tumoral nuclear β-catenin expression as an indicator of colorectal carcinoma progression and resistance to chemoradiotherapy in locally advanced rectal carcinoma

Programmed cell death-1 (PD-1) and its ligand (PD-L1) are significant mediators of immune suppression in the tumor microenvironment. We focused on the immunological impact of PD-1/PD-L1 signaling during tumor progression in colorectal carcinoma (CRC) and its association with resistance to neoadjuvant chemoradiotherapy (NCRT) in locally advanced rectal carcinoma (LAd-RC). Histopathological and immunohistochemical analyses of 100 CRC cases (including 34 RC) without NCRT and 109 NCRT-treated LAd-RC cases were performed. Membranous tumoral PD-L1 expression was identified in 9 of 100 (9%) CRC cases, including 1 of 34 (2.9%) RC cases, but PD-L1 immunopositivity was not associated with any clinicopathological factors, with the exception of deficient mismatch repair (dMMR) status. In contrast, stromal PD-L1+ immune cells, which frequently exhibited coexpression of PD-1 and CD8 markers, were significantly correlated with tumor vessel invasion, nuclear β-catenin+ tumor budding cancer stem cell (CSC)-like features, and unfavorable prognosis. In the LAd-RC cases, stromal CD8+ (but not PD-L1+) immune cell infiltration in pretreatment-biopsied samples was significantly and positively associated with therapeutic efficacy. After NCRT, tumoral PD-L1 expression was observed in only 2 of 83 (2.4%) tumors, independent of dMMR status, whereas high stromal PD-L1+ and tumoral nuclear β-catenin positivity were significantly linked to a poor response to NCRT and high tumor budding features. In addition, high stromal PD-L1 immunoreactivity was significantly associated with poorer overall survival. In conclusion, a combination of stromal PD-L1+ immune cells and nuclear β-catenin+ tumor budding may contribute to tumor progression in CRC and resistance to NCRT in LAd-RC, through formation of niche-like lesions that exhibit immune resistance and CSC properties.

Drug Resistance in Colorectal Cancer: From Mechanism to Clinic

Colorectal cancer (CRC) is one of the leading causes of death worldwide. The 5-year survival rate is 90% for patients with early CRC, 70% for patients with locally advanced CRC, and 15% for patients with metastatic CRC (mCRC). In fact, most CRC patients are at an advanced stage at the time of diagnosis. Although chemotherapy, molecularly targeted therapy and immunotherapy have significantly improved patient survival, some patients are initially insensitive to these drugs or initially sensitive but quickly become insensitive, and the emergence of such primary and secondary drug resistance is a significant clinical challenge. The most direct cause of resistance is the aberrant anti-tumor drug metabolism, transportation or target. With more in-depth research, it is found that cell death pathways, carcinogenic signals, compensation feedback loop signal pathways and tumor immune microenvironment also play essential roles in the drug resistance mechanism. Here, we assess the current major mechanisms of CRC resistance and describe potential therapeutic interventions.

Combined treatment with anti-PSMA CAR NK-92 cell and anti-PD-L1 monoclonal antibody enhances the antitumour efficacy against castration-resistant prostate cancer

BACKGROUND

The chimeric antigen receptor NK-92 (CAR NK-92) cell targeting the prostate-specific membrane antigen (PSMA) has shown antitumour effects in castration-resistant prostate cancer (CRPC). However, the expression changes of programmed death ligand 1 (PD-L1) and its mechanisms on CAR NK-92 and CRPC cells and the effect of the anti-PD-L1 monoclonal antibody (mAb) on PD-L1 expressed on CAR NK-92 cells remain unknown.

METHODS

Human dendritic cells and CD8+ T cells were acquired from blood samples of healthy donors and cocultured with C4-2 cells. Changes in PD-L1 expression were detected by flow cytometry. Differential gene expressions were investigated by RNA sequence analysis, while the regulation of PD-L1 molecular signaling was explored using western blotting. In vitro cytotoxicity was evaluated using the Cell Counting Kit-8 assay and the bioluminescent intensity (BLI) of green fluorescent protein-labelled C4-2 cells. CRPC growth in vivo was monitored using callipers and BLI in male NOD/SCID mice subcutaneously injected with C4-2 cells and treated intravenously with anti-PD-L1/PD-1 mAb, CAR NK-92 or cocultured CD8+ T cells.

RESULTS

Significantly upregulated expression of PD-L1k was observed in cocultured C4-2 and CAR NK-92 cells. In addition, upregulation of PD-L1 expression was dependent on interferon-γ in C4-2 cells, while it was dependent on direct cell-to-cell interaction via the NK group 2 member D/ phosphatidylinositol 3-kinase/AKT pathway in CAR NK-92 cells. The anti-PD-L1 mAb directly acted on PD-L1 expressed on CAR NK-92 cells and augmented the cytotoxicity of CAR NK-92 cells against C4-2 and CRPC cells from one patient in vitro. Anti-PD-L1 mAb significantly enhanced the antitumour effect of CAR NK-92 cells against CRPC cells in vivo when compared to treatment with CAR NK-92 cells or combined with anti-PD-1 mAb in the absence or presence of cocultured CD8+ T cells.

CONCLUSION

Combined treatment with CAR NK-92 and anti-PD-L1 mAb improved the antitumour efficacy against CRPC, which is of extraordinary translational value in the clinical treatment of CRPC.

HMGB1 mediates invasion and PD-L1 expression through RAGE-PI3K/AKT signaling pathway in MDA-MB-231 breast cancer cells

BACKGROUND

High-mobility group box 1 (HMGB1) is increased in breast cancer cells as the result of exposure to the secreted substances from cancer-associated fibroblasts and plays a crucial role in cancer progression and drug resistance. Its effect, however, on the expression of programmed death ligand 1 (PD-L1) in breast cancer cells has not been investigated. This study aimed to investigate the mechanism of HMGB1 through receptors for advanced glycation end products (RAGE) on cell migration/invasion and PD-L1 expression in breast cancer cells.

METHODS

A 3-dimensional (3-D) migration and invasion assay and Western blotting analysis to evaluate the function and the mechanism under recombinant HMGB1 (rHMGB1) treatment with knockdown of RAGE using shRAGE and PI3K/AKT inhibitors was performed.

RESULTS

The results revealed that rHMGB1 induced MDA-MB-231 cell migration and invasion. The knockdown of RAGE using shRAGE and PI3K/AKT inhibitors attenuated 3-D migration and invasion in response to rHMGB1 compared to mock cells. PD-L1 up-regulation was observed in both parental MDA-MB-231 (P) and MDA-MB-231 metastasis to bone marrow (BM) cells treated with rHMGB1, and these effects were alleviated in RAGE-knock down (KD) breast cancer cells as well as in PI3K/AKT inhibitor-treated cells.

CONCLUSIONS

Collectively, these findings indicate that HMGB1-RAGE through PI3K/AKT signaling promotes not only breast cancer cell invasion but also PD-L1 expression which leads to the destruction of the effector T cells. The attenuating HMGB1-RAGE-PI3K/AKT pathway may help to attenuate breast cancer cell aggressive phenotypes.

Roles of PTEN inactivation and PD-1/PD-L1 activation in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is the most common type of esophageal cancer in China and developing countries. The purpose of this review is to summarize the roles of inactivation of the tumor suppressor gene, phosphatase and tensin homolog (PTEN), and activation of the programmed cell death protein 1 (PD-1) upon binding to its ligand (PD-L1) in the promotion of ESCC. Studies of ESCC performed in vitro and in vivo indicated that PTEN and PD-L1 function in the regulation of cell proliferation, invasion, and migration; the epithelial-mesenchymal transition; resistance to chemotherapy and radiotherapy; and the PI3K/AKT signaling pathway. Certain genetic variants of PTEN are related to susceptibility to ESCC, and PTEN and PD-L1 also function in ESCC progression and affect the prognosis of patients with ESCC. There is also evidence that the expression of PD-L1 and PTEN are associated with the progression of certain other cancers. Future studies should further examine the relationship of PD-L1 and PTEN and their possible interactions in ESCC.

Improvement of the anticancer efficacy of PD-1/PD-L1 blockade via combination therapy and PD-L1 regulation

Immune checkpoint molecules are promising anticancer targets, among which therapeutic antibodies targeting the PD-1/PD-L1 pathway have been widely applied to cancer treatment in clinical practice and have great potential. However, this treatment is greatly limited by its low response rates in certain cancers, lack of known biomarkers, immune-related toxicity, innate and acquired drug resistance, etc. Overcoming these limitations would significantly expand the anticancer applications of PD-1/PD-L1 blockade and improve the response rate and survival time of cancer patients. In the present review, we first illustrate the biological mechanisms of the PD-1/PD-L1 immune checkpoints and their role in the healthy immune system as well as in the tumor microenvironment (TME). The PD-1/PD-L1 pathway inhibits the anticancer effect of T cells in the TME, which in turn regulates the expression levels of PD-1 and PD-L1 through multiple mechanisms. Several strategies have been proposed to solve the limitations of anti-PD-1/PD-L1 treatment, including combination therapy with other standard treatments, such as chemotherapy, radiotherapy, targeted therapy, anti-angiogenic therapy, other immunotherapies and even diet control. Downregulation of PD-L1 expression in the TME via pharmacological or gene regulation methods improves the efficacy of anti-PD-1/PD-L1 treatment. Surprisingly, recent preclinical studies have shown that upregulation of PD-L1 in the TME also improves the response and efficacy of immune checkpoint blockade. Immunotherapy is a promising anticancer strategy that provides novel insight into clinical applications. This review aims to guide the development of more effective and less toxic anti-PD-1/PD-L1 immunotherapies.

Colorectal Cancer-Associated Immune Exhaustion Involves T and B Lymphocytes and Conventional NK Cells and Correlates With a Shorter Overall Survival

Colorectal cancer (CRC) is one of the most common cancer worldwide, with a growing impact on public health and clinical management. Immunotherapy has shown promise in the treatment of advanced cancers, but needs to be improved for CRC, since only a limited fraction of patients is eligible for treatment, and most of them develop resistance due to progressive immune exhaustion. Here, we identify the transcriptional, molecular, and cellular traits of the immune exhaustion associated with CRC and determine their relationships with the patient's clinic-pathological profile. Bioinformatic analyses of RNA-sequencing data of 594 CRCs from TCGA PanCancer collection, revealed that, in the wide range of immune exhaustion genes, those coding for PD-L1, LAG3 and T-bet were associated (Cramér's V=0.3) with MSI/dMMR tumors and with a shorter overall survival (log-rank test: p=0.0004, p=0.0014 and p=0.0043, respectively), whereas high levels of expression of EOMES, TRAF1, PD-L1, FCRL4, BTLA and SIGLEC6 were associated with a shorter overall survival (log-rank test: p=0.0003, p=0.0188, p=0.0004, p=0.0303, p=0.0052 and p=0.0033, respectively), independently from the molecular subtype of CRC. Expression levels of PD-L1, PD-1, LAG3, EOMES, T-bet, and TIGIT were significantly correlated with each other and associated with genes coding for CD4⁺ and CD8⁺CD3⁺ T cell markers and NKp46⁺CD94⁺EOMES⁺T-bet⁺ cell markers, (OR >1.5, p<0.05), which identify a subset of group 1 innate lymphoid cells, namely conventional (c)NK cells. Expression of TRAF1 and BTLA co-occurred with both T cell markers, CD3γ, CD3δ, CD3ε, CD4, and B cell markers, CD19, CD20 and CD79a (OR >2, p<0.05). Expression of TGFβ1 was associated only with CD4 ⁺ and CD8⁺CD3ε⁺ T cell markers (odds ratio >2, p<0.05). Expression of PD-L2 and IDO1 was associated (OR >1.5, p<0.05) only with cNK cell markers, whereas expression of FCRL4, SIGLEC2 and SIGLEC6 was associated (OR >2.5; p<0.05) with CD19⁺CD20⁺CD79a⁺ B cell markers. Morphometric examination of immunostained CRC tissue sections, obtained from a validation cohort of 53 CRC patients, substantiated the biostatistical findings, showing that the highest percentage of immune exhaustion gene expressing cells were found in tumors from short-term survivors and that functional exhaustion is not confined to T lymphocytes, but also involves B cells, and cNK cells. This concept was strengthened by CYBERSORTx analysis, which revealed the expression of additional immune exhaustion genes, in particular FOXP1, SIRT1, BATF, NR4A1 and TOX, by subpopulations of T, B and NK cells. This study provides novel insight into the immune exhaustion landscape of CRC and emphasizes the need for a customized multi-targeted therapeutic approach to overcome resistance to current immunotherapy.

The modulation of PD-L1 induced by the oncogenic HBXIP for breast cancer growth

Programmed death ligand-1 (PD-L1)/PD-1 checkpoint extensively serves as a central mediator of immunosuppression. A tumor-promoting role for abundant PD-L1 in several cancers is revealed. However, the importance of PD-L1 and how the PD-L1 expression is controlled in breast cancer remains obscure. Here, the mechanisms of controlling PD-L1 at the transcription and protein acetylation levels in promoting breast cancer growth are presented. Overexpressed PD-L1 accelerates breast cancer growth in vitro and in vivo. RNA-seq uncovers that PD-L1 can induce some target genes affecting many cellular processes, especially cancer development. In clinical breast cancer tissues and cells, PD-L1 and HBXIP are both increased, and their expressions are positively correlated. Mechanistic exploration identifies that HBXIP stimulates the transcription of PD-L1 through co-activating ETS2. Specifically, HBXIP induces PD-L1 acetylation at K270 site through interacting with acetyltransferase p300, leading to the stability of PD-L1 protein. Functionally, depletion of HBXIP attenuates PD-L1-accelerated breast tumor growth. Aspirin alleviates breast cancer via targeting PD-L1 and HBXIP. Collectively, the findings display new light into the mechanisms of controlling tumor PD-L1 and broaden the utility for PD-L1 as a target in breast cancer therapy.

Directing hypoxic tumor microenvironment and HIF to illuminate cancer immunotherapy's existing prospects and challenges in drug targets

Cancer is now also reflected as a disease of the tumor microenvironment, primarily supposed to be a decontrolled genetic and cellular expression disease. Over the past two decades, significant and rapid progress has been made in recognizing the dynamics of the tumor's microenvironment and its contribution to influencing the response to various anti-cancer therapies and drugs. Modulations in the tumor microenvironment and immune checkpoint blockade are interesting in cancer immunotherapy and drug targets. Simultaneously, the immunotherapeutic strategy can be done by modulating the immune regulatory pathway; however, the tumor microenvironment plays an essential role in suppressing the antitumor's immunity by its substantial heterogeneity. Hypoxia inducible factor (HIF) is a significant contributor to solid tumor heterogeneity and a key stressor in the tumor microenvironment to drive adaptations to prevent immune surveillance. Checkpoint inhibitors here halt the ability of cancer cells to stop the immune system from activating, and in turn, amplify your body's immune system to help destroy cancer cells. Common checkpoints that these inhibitors affect are the PD-1/PD-L1 and CTLA-4 pathways and important drugs involved are Ipilimumab and Nivolumab, mainly along with other drugs in this group. Targeting the hypoxic tumor microenvironment may provide a novel immunotherapy strategy, break down traditional cancer therapy resistance, and build the framework for personalized precision medicine and cancer drug targets. We hope that this knowledge can provide insight into the therapeutic potential of targeting Hypoxia and help to develop novel combination approaches of cancer drugs to increase the effectiveness of existing cancer therapies, including immunotherapy.

Neu Perspectives, Therapies, and Challenges for Metastatic HER2-Positive Breast Cancer

Even though gene amplification or protein overexpression occurs in approximately one-fifth of all breast cancers, the discovery of HER2 has, nevertheless, had profound implications for the disease. Indeed, the characterization of the receptor resulted in a number of significant advances. Structurally, unique features provided avenues for the development of numerous compounds with target-specificity; molecularly, biological constructs revealed a highly complex, internal signal transduction pathway with regulatory effects on tumor proliferation, survival, and perhaps, even resistance; and clinically, disease outcomes manifested its predictive and prognostic value. Yet despite the receptor’s utility, the beneficial effects are diminished by tumor recurrence after neo- or adjuvant therapy as well as losses resulting from the inability to cure patients with metastatic disease. What these observations suggest is that while tumor response may be partially linked to uncoupling cell surface message reception and nuclear gene expression, as well as recruitment of the innate immune system, disease progression and/or resistance may involve a reprogrammable signaling mainframe that elicits alternative growth and survival signals. This review attempts to meld current perceptions related to HER2-positive metastatic breast cancer with particular attention to current biological insights and therapeutic challenges.

Mutant APC promotes tumor immune evasion via PD-L1 in colorectal cancer

PD-L1 expression is elevated in various human cancers, including colorectal cancer. High levels of PD-L1 expressed on tumor epithelial cells are one of the potential mechanisms by which tumor cells become resistant to immune attack. However, PD-L1 regulation in tumor cells is not fully understood. Here we demonstrate that mutations in the adenomatous polyposis coli (APC) gene lead to colonic epithelial cell resistance to CD8⁺ T cell cytotoxicity by induction of PD-L1 expression. Mechanistically, this occurs as a result of the β-catenin/TCF4 complex binding to the PD-L1 promoter, leading to increased transcription. Our findings not only reveal a novel mechanism by which APC mutations induce tumor immune evasion via an immune checkpoint pathway but also pave the way for developing β-catenin or TCF4 inhibitors as possible new options for immune checkpoint inhibition.

Leiomyosarcoma: Does Location of Primary Help to Determine the Best Systemic Therapy Options?

OPINION STATEMENT

Management of leiomyosarcoma is based on the specifics of each individual case. Specifically, the location of the disease and whether the disease is metastatic or localized and if localized disease, whether the tumor is resectable or unresectable. In patients with recurrent or metastatic disease, factors such as disease-free interval and pattern of spread should be considered within the context of treatment planning. In general, patients with metastatic disease are typically treated with systemic chemotherapy with either an anthracycline-based regimen or gemcitabine-based regimen as first-line therapy. Additional systemic options include trabectedin, pazopanib, eribulin, and DTIC. Uterine LMS has been the most studied site-specific LMS with respect to systemic therapy. The increasing use of tumor genomics may ultimately define subsets which may benefit from tailored systemic therapies.

Autophagy controls programmed death-ligand 1 expression on cancer cells (Review)

Programmed death-ligand 1 (PD-L1) is a transmembrane protein mainly located on cancer cells, including renal cell carcinoma, breast, colorectal, gastric and non-small cell lung cancer. PD-L1 binds to the PD-1 receptor expressed on T lymphocytes to inhibit the activation of T lymphocytes, thus allowing tumour cells to escape immune surveillance, leading to tumour growth and the poor prognosis of patients with cancer. Inhibitors targeting the programmed death-1/PD-L1 axis have been widely used in the clinical treatment of a variety of solid tumours in recent years. However, the clinical efficacy of these inhibitors varies. Studies have demonstrated that the effect of the targeted drug is positively associated with the expression of PD-L1 on the tumour membrane. Hence, exploring the mechanism of PD-L1 expression is very important for the treatment of tumours. Autophagy is a physiological process that maintains the stability of the internal environment. Autophagy degrades aging organelles and long-lived proteins and produces nutrients for cell recycling. To the best of our knowledge, the present review is the first to summarize the research that has been conducted on autophagy-regulated PD-L1 expression, which may provide new avenues for tumour immunotherapy.

PD-L1 and CD8-Tumor-Infiltrating Lymphocytes Expression in Laryngeal Squamous Cell Carcinoma

Studies in recent years have shown that the immune system plays an important role in the prognosis of patients with different types of malignancies. The tumor immune microenvironment has been studied in various cancers in an attempt to find new antitumoral therapies. The therapeutic blockade of PD-1/PD-L1 has revolutionized the treatment of oncological pacients, with anti-PD-L1 monoclonal antibodies having remarkable results in malignant melanoma, cervical, renal and lung cancer. In laryngeal cancer, few reports are available on the immune microenvironment and PD-L1 expression. Considering these, we retrospectively review 23 laryngeal cancer patients with laryngectomy performed in the Otorhinolaryngology Department - Emergency County Clinical Hospital St Andrew Constanta. The aim of our research was to evaluate the immunohistochemical expression of PD-L1, using combined positive score which includes both viable tumoral cells and intratumoral lymphocytes, as well as the level of CD8 intratumoral lymphocytes and to analise the corelation between these markers and the clinicopathological characteristics of the pacients, in order to set these two parameters, in the near future, as new biomarkers. PD-L1 expression was shown to be a prognostic factor for disease-free survival in laryngeal cancer patients (p = 0.006) and was higher in tumors with elevated CD8 lymphocyte levels, with a significant correlation correlation between the two parameters (p = 0.019). The level of CD8 lymphocytes was also a predictive factor for free-disease survival, correlated with patient smoker status (p = 0.04), being higher in non-smoking patients.

PI3K/Akt Pathway: The Indestructible Role of a Vintage Target as a Support to the Most Recent Immunotherapeutic Approaches

Simple Summary

PI3K/Akt pathway has an impressive story as tumor marker. PI3K-dependent solid tumors have been studied for several years in order to inhibit the pathway at different levels along the signaling. Despite the highly satisfactory results obtained in vitro and in xenograft mouse tumor models, the use of PI3K/Akt inhibitors in clinical trials resulted in being not as efficient as expected. With the emerging role of the tumor microenvironment in the response to therapy and the awareness, increasing in recent years, of the necessity to army the immune system against the tumor, new opportunities have emerged for PI3K/Akt inhibitors. Here, we show that PI3K/Akt, in addition to its function as tumor marker, exerts a pivotal role as an immunomodulator. Recent studies demonstrate that PI3K/Akt pathway is crucial for the regulation of the immune system and that its inhibition in combination with immunomodulatory agents may provide a new therapeutic approach for cancer.

Abstract

Pathologic activation of PI3Ks and the subsequent deregulation of its downstream signaling pathway is among the most frequent events associated with cellular transformation, cancer, and metastasis. PI3Ks are also emerging as critical factors in regulating anti-tumor immunity by either promoting an immunosuppressive tumor microenvironment or by controlling the activity and the tumor infiltration of cells involved in the immune response. For these reasons, significant pharmaceutical efforts are dedicated to inhibiting the PI3K pathway, with the main goal to target the tumor and, at the same time, to enhance the anti-tumor immunity. Recent immunotherapeutic approaches involving the use of adoptive cell transfer of autologous genetically modified T cells or immune check-point inhibitors showed high efficacy. However, mechanisms of resistance to these kinds of therapy are emerging, due in part to the inhibition of effector T cell functions exerted by the immunosuppressive tumor microenvironment. Here, we first describe how inhibition of PI3K/Akt pathway contribute to enhance anti-tumor immunity and further discuss how inhibitors of the pathway are used in combination with different immunomodulatory and immunotherapeutic agents to improve anti-tumor efficacy.