CMTM6 and CMTM4 as two novel regulators of PD-L1 modulate the tumor microenvironment

A review on comprehending immunotherapeutic approaches inducing ferroptosis: Managing tumour immunity

Ferroptosis, a necrotic, iron-dependent controlled cell death mechanism, is distinguished by the development of lipid peroxides to fatal proportions. Malignant tumours, influenced by iron to promote fast development, are vulnerable to ferroptosis. Based upon mounting evidence it has been observed that ferroptosis may be immunogenic and hence may complement immunotherapies. A new approach includes iron oxide-loaded nano-vaccines (IONVs), having supremacy for the traits of the tumour microenvironment (TME) to deliver specific antigens through improving the immunostimulatory capacity by molecular disintegration and reversible covalent bonds that target the tumour cells and induce ferroptosis. Apart from IONVs, another newer approach to induce ferroptosis in tumour cells is through oncolytic virus (OVs). One such oncolytic virus is the Newcastle Disease Virus (NDV), which can only multiply in cancer cells through the p53-SLC7A11-GPX4 pathway that leads to elevated levels of lipid peroxide and intracellular reactive oxygen species leading to the induction of ferroptosis that induce ferritinophagy.

Research insights into the chemokine-like factor (CKLF)-like MARVEL transmembrane domain-containing family (CMTM): their roles in various tumors

The chemokine-like factor (CKLF)-like MARVEL transmembrane domain-containing (CMTM) family includes CMTM1-8 and CKLF, and they play key roles in the hematopoietic, immune, cardiovascular, and male reproductive systems, participating in the physiological functions, cancer, and other diseases associated with these systems. CMTM family members activate and chemoattract immune cells to affect the proliferation and invasion of tumor cells through a similar mechanism, the structural characteristics typical of chemokines and transmembrane 4 superfamily (TM4SF). In this review, we discuss each CMTM family member's chromosomal location, involved signaling pathways, expression patterns, and potential roles, and mechanisms of action in pancreatic, breast, gastric and liver cancers. Furthermore, we discuss several clinically applied tumor therapies targeted at the CMTM family, indicating that CMTM family members could be novel immune checkpoints and potential targets effective in tumor treatment.

Molecular and immunological characteristics of patients with CMTM6 low expression colorectal cancer

CKLF-like MARVEL transmembrane domain-containing 6 (CMTM6), a regulator of programmed cell death ligand 1 (PD-L1), has attracted extensive attention due to its role in tumors. However, research on the expression of CMTM6 in colorectal cancer (CRC) and its relationship with PD-L1 expression and immune cell infiltration is limited. We used The Cancer Genome Atlas database to mine and analyze data from patients with CRC using bioinformatics methods. We investigated the expression of CMTM6 in CRC and its relationship with PD-L1 expression and immune cell infiltration. Immunohistochemistry and PCR were performed to detect CMTM6 and PD-L1 expression in CRC tissues. Differential gene expression analysis was performed using the edgeR package in R and immune cell infiltration analysis was performed using the ssGSEA algorithm. Additionally, GO and KEGG enrichment analyses were conducted to identify the biological processes and pathways associated with low CMTM6 expression. Our study found that CMTM6 expression was significantly upregulated in CRC tissues compared to that in adjacent normal tissues. Patients with high CMTM6 expression exhibited significantly increased levels of PD-L1 expression and higher levels of tumor-infiltrating immune cells compared to patients with low CMTM6 expression. GO and KEGG analyses suggested that CMTM6 may be involved in multiple immune regulatory pathways in CRC.

Macrophage metabolism, phenotype, function, and therapy in hepatocellular carcinoma (HCC)

The pivotal role of the tumor microenvironment (TME) in the initiation and advancement of hepatocellular carcinoma (HCC) is widely acknowledged, as it fosters the proliferation and metastasis of HCC cells. Within the intricate TME of HCC, tumor-associated macrophages (TAMs) represent a significant constituent of non-malignant cells. TAMs engage in direct communication with cancer cells in HCC, while also exerting influence on other immune cells to adopt a tumor-supportive phenotype that facilitates tumor progression. Among the multifaceted mechanisms at play, the metabolic reprogramming of both tumor cells and macrophages leads to phenotypic alterations and functional modifications in macrophages. This comprehensive review elucidates the intricate interplay between cellular metabolism and macrophage phenotype/polarization, while also providing an overview of the associated signaling molecules and potential therapeutic strategies for HCC.

Circular RNA hsa_circ_0067842 facilitates tumor metastasis and immune escape in breast cancer through HuR/CMTM6/PD-L1 axis

BACKGROUND

Circular RNAs (circRNAs) have been shown to play diverse biological functions in the progression of multiple diseases. However, the impacts of circRNAs on breast cancer (BC) progression remains unclear. Therefore, the objective of this paper is to investigate the role and mechanisms of a functional circRNA in BC metastasis and immune escape.

METHODS

This study used a circRNA microarray and identified a novel circRNA hsa_circ_0067842. The validation and characteristics of hsa_circ_0067842 were investigated using qRT-PCR, sanger sequencing, RNase R treatment, actinomycin D treatment and fluorescence in situ hybridization (FISH). Gain- and loss-of-function assays were performed to evaluate the biological function of hsa_circ_0067842 in BC progression and immune escape. Mechanistically, the interaction between hsa_circ_0067842 and HuR was explored by RNA pull down, mass spectrometry (MS), subcellular component protein extraction and immunofluorescence (IF). The regulatory mechanisms of hsa_circ_0067842/HuR/CMTM6/PD-L1 axis were investigated by qRT-PCR, western blot, FISH, immunoprecipitation and rescue assays.

RESULTS

The expression of hsa_circ_0067842 was upregulated in BC tissues and cells, which was found to be significantly associated with poor prognosis, regardless of other clinical covariates. Function assays showed that hsa_circ_0067842 promoted the migration and invasion capacities of BC cells. Moreover, co-culture experiment with peripheral blood mononuclear cells (PBMCs) showed that hsa_circ_0067842 played a role in the immune escape of BC cells. Mechanistically, our study showed that hsa_circ_0067842 interacted with HuR, affecting its nuclear translocation, thus enhancing the stability of CMTM6. CMTM6 not only enhances the migration and invasion ability of BC cells, but also affects the ubiquitination of PD-L1 and inhibits its degradation.

CONCLUSION

Collectively, our results demonstrated that hsa_circ_0067842 promoted BC progression through the HuR/CMTM6/PD-L1 axis, providing new insight and a potential target for BC prognosis and therapy.

SERPINE1 as an Independent Prognostic Marker and Therapeutic Target for Nicotine-Related Oral Carcinoma

OBJECTIVES

Nicotine is an ingredient of tobacco, and exposure to nicotine increases the risks of various cancers, including oral cancer. Previous studies have focused on the addictive properties of nicotine, but its carcinogenic mechanism has rarely been studied. We aimed to explore the key genes in the process through which nicotine promotes the occurrence and development of oral cancer via data mining and experimental verification.

METHODS

This study involved three parts. First, key genes related to nicotine-related oral cancer were screened through data mining; second, the expression and clinical significance of a key gene in oral cancer tissues were verified by bioinformatics. Finally, the expression and clinical significance of the key gene in oral cancer were histologically investigated, and the effects of its expression on cell proliferation, invasion, and drug resistance were cytologically assessed.

RESULTS

SERPINE1 was identified as the key gene, which was upregulated in nicotine-treated oral cells and may be an independent prognostic factor for oral cancer. SERPINE1 was enriched in various pathways, such as the tumor necrosis factor and apelin pathways, and was related to the infiltration of macrophages, CD4+T cells, and CD8+T cells. Overexpression of SERPINE1 was associated with N staging and may be involved in hypoxia, angiogenesis, and metastasis. Knockdown of SERPINE1 in oral cancer cells resulted in weakened cell proliferation and invasion ability and increased sensitivity to bleomycin and docetaxel.

CONCLUSION

This study revealed SERPINE1 as a key gene for nicotine-related oral cancer, indicating that SERPINE1 may be a novel prognostic indicator and therapeutic target for oral carcinoma.

Deciphering the potential roles of ferroptosis in regulating tumor immunity and tumor immunotherapy

Cancer immunotherapies, including immune checkpoint inhibition (ICI) and adoptive immune cells therapy, are promising therapeutic strategies. They reactivate the function of immune cells and induce immune responses to attack tumor cells. Although these novel therapies benefited a large amount of cancer patients, many cancer patients have shown fair responses even resistance to cancer immunotherapies, limiting their wide clinical application. Therefore, it is urgent to explore the underlying mechanisms of low response and resistance of cancer immunotherapy to enhance their treatment efficacy. The programmed cell death (PCD) including the ferroptosis, has been demonstrated to play essential roles in antitumor immunity and in regulating the immune response to ICIs. Ferroptosis, a phospholipid peroxidation-mediated, iron-dependent membrane damage, exhibite three critical hallmarks: the oxidation of phospholipids, the lack of lipid peroxide repair capability and the overloading of redox-active iron. Notably, ferroptosis was found to plays important roles in regulating tumor immunity and response to immunotherapy. Therefore, targeting ferroptosis alone or in combination with immunotherapy may provide novel options to promote their antitumor efficacy. However, the effect of ferroptosis on tumor immunity and immunotherapy is affected by the interaction of ferroptosis and cancer cells, immune cells, tumor microenvironment (TME) and others. In this review, we summarized and discussed the critical roles of ferroptosis in regulating antitumor immunity, TME and in the improvement of the therapeutic efficacy of immunotherapy in cancers.