Inter-Tumor Heterogeneity-Melanomas Respond Differently to GM-CSF-Mediated Activation

Granulocyte-Macrophage Colony-Stimulating Factor in Combination With Chemoradiation for Recurrent or Metastatic Cervical Cancer

Recurrent or metastatic cervical cancer carries a bleak prognosis and presents a formidable challenge in terms of treatment. Granulocyte-macrophage colony-stimulating factor (GM-CSF) increases the body's immune response by enhancing antigen presentation, which has been rarely reported in recurrent or metastatic cervical cancer. A 44-year-old woman presented to the hospital with vaginal bleeding four years after radical hysterectomy for stage IB2 squamous cell carcinoma (SCC) of the cervix (grade II-III). Gynecological examination and imaging revealed a vaginal mass, and the biopsy confirmed the recurrence of grade III SCC. The patient was treated with chemoradiation (CRT) combined with immunoadjuvant GM-CSF and achieved complete remission and a progression-free survival of two years.

A heterodimer of α and β hemoglobin chains functions as an innate anticancer agent

Metastatic (as well as tumor) microenvironments contain both cancer-promoting and cancer-restraining factors. The balance between these opposing forces determines the fate of cancer cells that disseminate to secondary organ sites. In search for microenvironmental drivers or inhibitors of metastasis, we identified, in a previous study, the beta subunit of hemoglobin (HBB) as a lung-derived antimetastatic factor. In the present study, exploring mechanisms regulating melanoma brain metastasis, we discovered that brain-derived factors restrain proliferation and induce apoptosis and necrosis of brain-metastasizing melanoma cells. Employing various purification procedures, we identified a heterodimer composed of hemoglobin alpha and beta chains that perform these antimetastatic functions. Neither the alpha nor the beta subunit alone was inhibitory. An alpha/beta chain dimer chemically purified from human hemoglobin inhibited the cell viability of primary melanomas, melanoma brain metastasis (MBM), and breast cancer cell lines. The dimer-induced DNA damage, cell cycle arrest at the SubG1 phase, apoptosis, and significant necrosis in four MBM cell lines. Proteomic analysis of dimer-treated MBM cells revealed that the dimer downregulates the expression of BRD4, GAB2, and IRS2 proteins, playing crucial roles in cancer cell sustainability and progression. Thus, we hypothesize that the hemoglobin dimer functions as a resistance factor against brain-metastasizing cancer cells.

Heterogeneity in the Metastatic Microenvironment: JunB-Expressing Microglia Cells as Potential Drivers of Melanoma Brain Metastasis Progression

Reciprocal signaling between melanoma brain metastatic (MBM) cells and microglia reprograms the phenotype of both interaction partners, including upregulation of the transcription factor JunB in microglia. Here, we aimed to elucidate the impact of microglial JunB upregulation on MBM progression. For molecular profiling, we employed RNA-seq and reverse-phase protein array (RPPA). To test microglial JunB functions, we generated microglia variants stably overexpressing JunB (JunBhi) or with downregulated levels of JunB (JunBlo). Melanoma-derived factors, namely leukemia inhibitory factor (LIF), controlled JunB upregulation through Janus kinase (JAK)/signal transducer and activator of transcription 3 (STAT3) signaling. The expression levels of JunB in melanoma-associated microglia were heterogeneous. Flow cytometry analysis revealed the existence of basal-level JunB-expressing microglia alongside microglia highly expressing JunB. Proteomic profiling revealed a differential protein expression in JunBhi and JunBlo cells, namely the expression of microglia activation markers Iba-1 and CD150, and the immunosuppressive molecules SOCS3 and PD-L1. Functionally, JunBhi microglia displayed decreased migratory capacity and phagocytic activity. JunBlo microglia reduced melanoma proliferation and migration, while JunBhi microglia preserved the ability of melanoma cells to proliferate in three-dimensional co-cultures, that was abrogated by targeting leukemia inhibitory factor receptor (LIFR) in control microglia-melanoma spheroids. Altogether, these data highlight a melanoma-mediated heterogenous effect on microglial JunB expression, dictating the nature of their functional involvement in MBM progression. Targeting microglia highly expressing JunB may potentially be utilized for MBM theranostics.

The Vicious Cycle of Melanoma-Microglia Crosstalk: Inter-Melanoma Variations in the Brain-Metastasis-Promoting IL-6/JAK/STAT3 Signaling Pathway

Previous studies from our lab demonstrated that the crosstalk between brain-metastasizing melanoma cells and microglia, the macrophage-like cells of the central nervous system, fuels progression to metastasis. In the present study, an in-depth investigation of melanoma-microglia interactions elucidated a pro-metastatic molecular mechanism that drives a vicious melanoma-brain-metastasis cycle. We employed RNA-Sequencing, HTG miRNA whole transcriptome assay, and reverse phase protein arrays (RPPA) to analyze the impact of melanoma-microglia interactions on sustainability and progression of four different human brain-metastasizing melanoma cell lines. Microglia cells exposed to melanoma-derived IL-6 exhibited upregulated levels of STAT3 phosphorylation and SOCS3 expression, which, in turn, promoted melanoma cell viability and metastatic potential. IL-6/STAT3 pathway inhibitors diminished the pro-metastatic functions of microglia and reduced melanoma progression. SOCS3 overexpression in microglia cells evoked microglial support in melanoma brain metastasis by increasing melanoma cell migration and proliferation. Different melanomas exhibited heterogeneity in their microglia-activating capacity as well as in their response to microglia-derived signals. In spite of this reality and based on the results of the present study, we concluded that the activation of the IL-6/STAT3/SOCS3 pathway in microglia is a major mechanism by which reciprocal melanoma-microglia signaling engineers the interacting microglia to reinforce the progression of melanoma brain metastasis. This mechanism may operate differently in different melanomas.

Identification of Transcriptional Heterogeneity and Construction of a Prognostic Model for Melanoma Based on Single-Cell and Bulk Transcriptome Analysis

Melanoma is one of the most aggressive and heterogeneous life-threatening cancers. However, the heterogeneity of melanoma and its impact on clinical outcomes are largely unknown. In the present study, intra-tumoral heterogeneity of melanoma cell subpopulations was explored using public single-cell RNA sequencing data. Marker genes, transcription factor regulatory networks, and gene set enrichment analysis were further analyzed. Marker genes of each malignant cluster were screened to create a prognostic risk score, and a nomogram tool was further generated to predict the prognosis of melanoma patients. It was found that malignant cells were divided into six clusters by different marker genes and biological characteristics in which the cell cycling subset was significantly correlated with unfavorable clinical outcomes, and the Wnt signaling pathway-enriched subset may be correlated with the resistance to immunotherapy. Based on the malignant marker genes, melanoma patients in TCGA datasets were divided into three groups which had different survival rates and immune infiltration states. Five malignant cell markers (PSME2, ARID5A, SERPINE2, GPC3, and S100A11) were selected to generate a prognostic risk score. The risk score was associated with overall survival independent of routine clinicopathologic characteristics. The nomogram tool showed good performance with an area under the curve value of 0.802.

Overcoming sunitinib resistance with tocilizumab in renal cell carcinoma: Discordance between in vitro and in vivo effects

Sunitinib is one of the first-line multi-tyrosine kinase inhibitors for metastatic renal cell carcinoma, and resistance to sunitinib continues to be a limiting factor for the successful treatment. As interleukin-6 (IL-6) is overexpressed in sunitinib-resistant cells, the purpose of this study was to explore the potential of IL-6 inhibition with tocilizumab, an IL-6 receptor inhibitor, to overcome resistance. In vitro, two sunitinib-resistant renal cell carcinoma cell lines (Caki-1 and SN12K1) were treated with tocilizumab. A mouse subcutaneous xenograft model was also used. Cell viability was studied by MTT assay, and apoptosis by morphology and ApopTag. Expression of IL-6, vascular endothelial growth factor (VEGF), and Bcl-2 was analyzed by qPCR. In vitro, tocilizumab induced significant cell death, and reduced the expression of IL-6, VEGF, and Bcl-2 in sunitinib-resistant cells. However, the in vitro findings could not be successfully translated in vivo, as tocilizumab did not decrease the growth of the tumors.

Cancer microenvironment and genomics: evolution in process

Cancer heterogeneity is a result of genetic mutations within the cancer cells. Their proliferation is not only driven by autocrine functions but also under the influence of cancer microenvironment, which consists of normal stromal cells such as infiltrating immune cells, cancer-associated fibroblasts, endothelial cells, pericytes, vascular and lymphatic channels. The relationship between cancer cells and cancer microenvironment is a critical one and we are just on the verge to understand it on a molecular level. Cancer microenvironment may serve as a selective force to modulate cancer cells to allow them to evolve into more aggressive clones with ability to invade the lymphatic or vascular channels to spread to regional lymph nodes and distant sites. It is important to understand these steps of cancer evolution within the cancer microenvironment towards invasion so that therapeutic strategies can be developed to control or stop these processes.

The melanoma brain metastatic microenvironment: aldolase C partakes in shaping the malignant phenotype of melanoma cells - a case of inter-tumor heterogeneity

Previous studies indicated that microglia cells upregulate the expression of aldolase C (ALDOC) in melanoma cells. The present study using brain‐metastasizing variants from three human melanomas explores the functional role of ALDOC in the formation and maintenance of melanoma brain metastasis (MBM). ALDOC overexpression impacted differentially the malignant phenotype of these three variants. In the first variant, ALDOC overexpression promoted cell viability, adhesion to and transmigration through a layer of brain endothelial cells, and amplified brain micrometastasis formation. The cross‐talk between this MBM variant and microglia cells promoted the proliferation and migration of the latter cells. In sharp contrast, ALDOC overexpression in the second brain‐metastasizing melanoma variant reduced or did not affect the same malignancy features. In the third melanoma variant, ALDOC overexpression augmented certain characteristics of malignancy and reduced others. The analysis of biological functions and disease pathways in the ALDOC overexpressing variants clearly indicated that ALDOC induced the expression of tumor progression promoting genes in the first variant and antitumor progression properties in the second variant. Overall, these results accentuate the complex microenvironment interactions between microglia cells and MBM, and the functional impact of intertumor heterogeneity. Since intertumor heterogeneity imposes a challenge in the planning of cancer treatment, we propose to employ the functional response of tumors with an identical histology, to a particular drug or the molecular signature of this response, as a predictive indicator of response/nonresponse to this drug.