Recombinant Human Transmembrane protein 170B (TMEM170B)

What is TMEM170B and what is its basic structure?

TMEM170B is a transmembrane protein belonging to the TMEM170 family. It is composed of 132 amino acids with sequences that are highly conserved from invertebrates to mammals . As a transmembrane protein, TMEM170B is embedded in cellular membranes and plays various roles in cellular signaling and function. Its structure includes transmembrane domains that anchor it within membrane bilayers, allowing interaction with both intracellular and extracellular environments. For structural characterization, researchers typically employ protein modeling, X-ray crystallography, or cryo-electron microscopy, though comprehensive structural studies on TMEM170B remain limited in current literature. When designing experiments to study TMEM170B structure, consideration should be given to protein isolation techniques that maintain native conformation of transmembrane proteins, which often require specialized detergents or nanodiscs.

Where is TMEM170B located in the human genome and how is it evolutionarily conserved?

TMEM170B is mapped to human chromosome 6p24.2, which provides important context for understanding potential regulatory elements and genomic alterations . This chromosomal location is significant for researchers examining genetic variations, copy number alterations, or epigenetic modifications affecting TMEM170B expression. The high evolutionary conservation of TMEM170B sequences across species suggests functional importance and selective pressure to maintain its role throughout evolution. When studying potential genetic alterations affecting TMEM170B, researchers should employ techniques such as fluorescence in situ hybridization (FISH), chromosomal microarrays, or next-generation sequencing approaches. Comparative genomic analyses across species may also provide insights into conserved functional domains and regulatory elements governing TMEM170B expression.

What are the known paralogues of TMEM170B and their functional differences?

The primary paralogue of TMEM170B is TMEM170A, which functions as a regulator of endoplasmic reticulum (ER) and nuclear envelope morphogenesis . While TMEM170A and TMEM170B share sequence similarities, they appear to have distinct functional roles in cellular processes. A transcriptome-wide association study revealed that TMEM170A expression is significantly associated with pancreatic cancer risk, suggesting both paralogues may have roles in cancer biology . When investigating TMEM170B, researchers should consider potential functional redundancy or complementary activities with TMEM170A through comparative expression analyses and simultaneous functional studies. Experimental designs might include single and double knockdown/knockout approaches to identify unique and overlapping functions, as well as rescue experiments to determine functional substitution capabilities between the paralogues.

How is TMEM170B expression regulated in normal and cancer cells?

TMEM170B is a direct target of miR-27a, which is significantly upregulated in breast cancer, resulting in TMEM170B downregulation . This microRNA-mediated regulation occurs through binding to the 3' untranslated region of TMEM170B mRNA, leading to degradation or translational repression. To confirm direct miRNA targeting, researchers typically employ luciferase reporter assays with wild-type and mutated binding sites. Beyond miRNA regulation, TMEM170B expression appears to correlate with tissue differentiation status, particularly in pancreatic cancer where low expression associates with poor differentiation . While not explicitly described in the search results, additional potential regulatory mechanisms might include transcription factors, epigenetic modifications, or post-translational modifications. For comprehensive analysis of TMEM170B regulation, researchers should consider multi-omics approaches integrating transcriptomics, epigenomics, and proteomics data.

What are the molecular mechanisms through which TMEM170B inhibits cancer progression?

TMEM170B inhibits cancer progression through multiple molecular mechanisms. In breast cancer, TMEM170B overexpression promotes cytoplasmic β-catenin phosphorylation, inhibiting β-catenin stabilization and nuclear translocation, which reduces expression of downstream Wnt target genes . This negative regulation of the canonical Wnt signaling pathway directly impacts cancer cell proliferation and survival. In pancreatic cancer, TMEM170B expression significantly associates with the tumor immune microenvironment . High TMEM170B expression positively correlates with infiltration of antitumor immune cells, including B cells, CD8+T cells, CD4+T cells, dendritic cells, natural killer cells, and M1 macrophages . Conversely, TMEM170B expression negatively correlates with immunosuppressive myeloid-derived suppressor cells (MDSCs) and regulatory T cells . These findings suggest TMEM170B may inhibit cancer progression both through direct effects on cancer cells and by modulating the tumor immune microenvironment. To investigate these mechanisms, researchers should employ western blotting for signaling pathway analysis, immunofluorescence for protein localization, co-immunoprecipitation for protein-protein interactions, and flow cytometry or multiplex immunohistochemistry for immune cell profiling.

How does TMEM170B interact with the Wnt/β-catenin signaling pathway?

TMEM170B has been shown to interact with the Wnt/β-catenin pathway, particularly in breast cancer. TMEM170B overexpression promotes cytoplasmic β-catenin phosphorylation, inhibiting β-catenin stabilization and reducing nuclear β-catenin levels and downstream target expression . This interaction has significant implications for cancer development, as β-catenin is a key component of the canonical Wnt signaling pathway frequently dysregulated in various cancers. By preventing β-catenin nuclear translocation, TMEM170B suppresses expression of Wnt target genes that typically promote cancer cell proliferation and survival . For investigating this interaction, researchers should employ techniques including western blotting to assess β-catenin phosphorylation status, nuclear/cytoplasmic fractionation to examine β-catenin localization, TOPFlash/FOPFlash luciferase reporter assays to measure Wnt signaling activity, and co-immunoprecipitation to detect potential direct interactions. Additionally, examining expression of downstream Wnt target genes such as c-Myc, cyclin D1, and survivin provides further evidence of pathway modulation.

What are the most effective methods to detect and quantify TMEM170B expression in tissue samples?

Several complementary methods have been employed to detect TMEM170B expression in tissue samples. Immunohistochemistry (IHC) has been used to assess TMEM170B protein expression in pancreatic cancer tissues, with results quantitatively analyzed using ImageJ software . Real-time polymerase chain reaction (RT-PCR) has been utilized to determine TMEM170B mRNA expression in human cancer cell lines and tissue specimens . RNA sequencing data from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) databases have been analyzed to assess TMEM170B expression at the transcriptome level . Each method offers distinct advantages: IHC provides spatial information about protein expression within tissue architecture but may be limited by antibody specificity; RT-PCR offers highly sensitive quantitative assessment of mRNA levels but doesn't provide protein or spatial information; RNA-seq provides comprehensive transcriptomic data but requires sophisticated bioinformatic analysis. For optimal TMEM170B expression analysis, researchers should consider employing multiple complementary techniques with appropriate controls, including housekeeping genes for RT-PCR and validated antibodies for IHC or western blotting.

How can researchers effectively manipulate TMEM170B expression in experimental models?

While the search results don't explicitly detail methods for manipulating TMEM170B expression, standard molecular biology techniques would be applicable. For overexpression studies, researchers could use plasmid-based expression vectors containing the TMEM170B coding sequence under a constitutive (e.g., CMV) or inducible promoter (e.g., tetracycline-responsive). These constructs can be introduced into cells via lipid-based transfection, electroporation, or viral transduction, depending on cell type and experimental goals. For knockdown or knockout studies, RNA interference (siRNA or shRNA) provides transient or stable reduction in expression, while CRISPR-Cas9 genome editing allows complete gene knockout or precise mutations. For temporal control of expression, inducible systems such as Tet-On/Tet-Off or estrogen receptor fusion proteins might be employed. When manipulating TMEM170B expression, researchers should validate modification effectiveness through quantitative RT-PCR and western blotting, and should consider potential off-target effects, compensatory mechanisms (particularly from paralog TMEM170A), and appropriate control conditions for all experiments.

What cell and animal models are most appropriate for studying TMEM170B function?

Selection of appropriate experimental models for TMEM170B research should be guided by specific research questions and cancer types of interest. For breast cancer research, common cell lines like MCF-7, MDA-MB-231, or T47D might be appropriate, while pancreatic cancer studies could utilize cell lines such as PANC-1, MIA PaCa-2, or BxPC-3. When selecting cell models, researchers should consider baseline TMEM170B expression levels (which may vary across cell lines), relevant genetic background, and active signaling pathways of interest. For in vivo studies, xenograft models using cell lines with manipulated TMEM170B expression provide insights into effects on tumor growth and metastasis. Genetically engineered mouse models with tissue-specific TMEM170B alterations would allow study of its role in tumor initiation and progression in immunocompetent hosts. Patient-derived xenografts or organoids offer more clinically relevant models that maintain tumor heterogeneity and microenvironment features. For immunological studies related to TMEM170B, syngeneic mouse models or humanized mouse models would be necessary to examine interactions with the immune system.

What are the key considerations when designing experiments to study TMEM170B's role in cancer?

When designing experiments to study TMEM170B's role in cancer, several key considerations must be addressed. First, selection of appropriate experimental models is crucial, as TMEM170B functions as a tumor suppressor across different cancer types . Researchers should select cell lines or animal models based on baseline TMEM170B expression, specific cancer type, and research questions. Second, expression manipulation strategies (overexpression, knockdown, or knockout) should be carefully designed with appropriate controls and validation methods. Third, comprehensive functional assays should assess TMEM170B's impact on cancer hallmarks including proliferation, migration, invasion, apoptosis, and cell cycle progression. Fourth, mechanistic studies should investigate how TMEM170B exerts its effects, focusing on its interaction with the β-catenin pathway and impact on tumor immune microenvironment . Fifth, clinical relevance should be established through correlative studies with patient samples or survival data from public databases . Finally, statistical analysis plans should be pre-specified with appropriate sample sizes to ensure sufficient power for detecting biologically meaningful effects.

How does TMEM170B influence the tumor microenvironment and immune cell infiltration?

TMEM170B expression demonstrates significant associations with tumor immune microenvironment components. In pancreatic adenocarcinoma, high TMEM170B expression correlates with elevated immuneScore, StromalScore, and ESTIMATEScore, indicating greater immune and stromal cell infiltration . Specifically, TMEM170B expression positively correlates with infiltration of antitumor immune cells, including B cells, CD8+T cells, CD4+T cells, dendritic cells, natural killer cells, neutrophils, monocytes, and M1 macrophages . Conversely, TMEM170B expression negatively correlates with immunosuppressive myeloid-derived suppressor cells (MDSCs) and regulatory T cells . Immunohistochemical validation confirmed these correlations, showing that TMEM170B had strong positive associations with tumor-infiltrating CD4+ and CD8+ T cells, and negative correlations with MDSCs . These findings suggest TMEM170B may exert tumor suppressive effects partly through modulating the immune microenvironment, enhancing antitumor immunity while reducing immunosuppressive components. For comprehensive investigation of these relationships, researchers should employ multiparametric flow cytometry, single-cell RNA sequencing, spatial transcriptomics, or multiplex immunohistochemistry to characterize immune profiles in relation to TMEM170B expression across different tumor types and stages.

What is the relationship between TMEM170B and immune checkpoint molecules?

Gene-by-gene correlation analysis revealed that common immune checkpoint genes, including PDCD1 (PD1), CD274 (PDL1), CTLA4, LAG3, and HAVCR2 (TIM3), positively correlate with TMEM170B expression in pancreatic adenocarcinoma . This relationship suggests TMEM170B might have value in predicting responsiveness to immune checkpoint inhibitor therapies . The positive correlation between TMEM170B and immune checkpoint molecules presents an interesting paradox, as TMEM170B appears to promote antitumor immunity while checkpoint molecules typically mediate immune suppression. This apparent contradiction warrants further investigation and might reflect complex regulatory relationships, compensatory mechanisms, or context-dependent effects in the tumor microenvironment. For researchers exploring this relationship, approaches should include correlation analyses in larger multi-cancer datasets, experimental manipulation of TMEM170B followed by assessment of checkpoint molecule expression, or investigation of shared regulatory pathways. Studies examining treatment responses to immune checkpoint inhibitors stratified by TMEM170B expression levels would provide particularly valuable insights into potential clinical applications.

What are the potential therapeutic applications targeting TMEM170B in cancer treatment?

TMEM170B shows significant promise as a therapeutic target in cancer treatment strategies. As a tumor suppressor downregulated in breast and pancreatic cancers , approaches aimed at restoring or enhancing TMEM170B expression or function could provide therapeutic benefits. Several potential therapeutic strategies emerge from current research: (1) Gene therapy approaches to restore TMEM170B expression in tumors with low expression; (2) MicroRNA inhibition strategies targeting miR-27a, which suppresses TMEM170B expression in breast cancer ; (3) Small molecules that mimic TMEM170B function or enhance its stability; (4) Combination approaches pairing TMEM170B-targeting with immune checkpoint inhibitors, leveraging the positive correlation between TMEM170B and antitumor immune cell infiltration . The relationship between TMEM170B and the Wnt/β-catenin pathway also suggests potential synergy with Wnt pathway inhibitors in development. For pancreatic cancer, which has limited effective treatment options, targeting TMEM170B might offer a novel therapeutic approach. Development of these therapeutic strategies would require systematic preclinical evaluation in cell models, organoids, and animal models before clinical translation.

What are the current limitations and knowledge gaps in TMEM170B research?

Despite valuable insights into TMEM170B's roles in cancer, several significant limitations and knowledge gaps remain. First, the molecular mechanisms linking TMEM170B to its downstream effects are only partially understood—while its interaction with the β-catenin pathway has been established in breast cancer and associations with immune cell infiltration observed in pancreatic cancer , the direct molecular intermediaries remain unclear. Second, TMEM170B research has primarily focused on breast and pancreatic cancers, leaving its roles in other cancer types largely unexplored. Third, the detailed structural biology of TMEM170B, including functional domains and interaction partners, requires further characterization. Fourth, while miR-27a has been identified as a regulator in breast cancer , comprehensive understanding of TMEM170B regulation across tissues and conditions is lacking. Fifth, the functional relationship between TMEM170B and its paralog TMEM170A remains poorly defined. Addressing these limitations will require multidisciplinary approaches combining structural biology, systems biology, and translational research to develop a comprehensive understanding of TMEM170B biology.

How might TMEM170B be utilized in combination therapy approaches for cancer treatment?

Current research suggests significant potential for TMEM170B in combination therapy approaches, particularly with immunotherapies. In pancreatic adenocarcinoma, TMEM170B expression positively correlates with antitumor immune cell infiltration and immune checkpoint gene expression, suggesting it might influence responses to immunotherapy . The study authors specifically note that "TMEM170B can be a potential prognostic biomarker and immunotherapy agent in combination therapy regimens to improve pancreatic cancer treatment" . Several promising combination approaches emerge: (1) Pairing strategies to enhance TMEM170B expression with immune checkpoint inhibitors (anti-PD1/PDL1, anti-CTLA4); (2) Combining TMEM170B-targeting with conventional chemotherapy or radiation to enhance treatment responses; (3) Dual targeting of TMEM170B and the Wnt/β-catenin pathway, given their established interaction in breast cancer . For effective development of combination approaches, researchers should employ preclinical models testing various drug combinations with careful assessment of potential synergistic and antagonistic effects. Drug scheduling, dosing optimization, and evaluation of biomarkers for response prediction will be critical components of combination therapy development.

What promising future research directions might advance TMEM170B understanding and applications?

Several promising directions for future TMEM170B research emerge from current findings. First, expanding investigation to additional cancer types beyond breast and pancreatic cancers would determine whether TMEM170B's tumor suppressive roles are universal or context-dependent. Second, deeper mechanistic studies employing proteomics and interactome analysis could elucidate TMEM170B's protein interaction network, revealing how it influences β-catenin signaling, immune cell recruitment, and potentially other pathways. Third, high-throughput screening approaches could identify compounds that modulate TMEM170B expression or mimic its function, providing leads for therapeutic development. Fourth, investigating the relationship between TMEM170B and its paralog TMEM170A might reveal functional redundancies or unique roles. Fifth, single-cell analyses of TMEM170B expression within tumor ecosystems could provide insights into cell type-specific functions and heterogeneity. Sixth, structural biology approaches like cryo-EM could determine TMEM170B's three-dimensional structure, enabling structure-based drug design. For researchers pursuing these directions, integrating multi-omics approaches with functional validation in diverse experimental models will likely yield the most comprehensive insights.

How might TMEM170B research contribute to personalized medicine approaches in oncology?

TMEM170B research has significant potential to contribute to personalized medicine approaches in cancer treatment. The strong prognostic value of TMEM170B expression in breast and pancreatic cancers suggests its utility as a biomarker for patient stratification . Patients with low TMEM170B expression demonstrate worse prognosis and might benefit from more aggressive treatment strategies or specific targeted approaches addressing TMEM170B deficiency. The association between TMEM170B expression and immune cell infiltration suggests it might predict responses to immunotherapy, potentially identifying patients most likely to benefit from immune checkpoint inhibitors . Furthermore, understanding mechanisms of TMEM170B downregulation, such as miR-27a upregulation in breast cancer , could lead to tailored therapeutic strategies addressing these specific regulatory mechanisms. Development of clinically applicable TMEM170B expression assays (IHC, RT-PCR, or RNA-seq based) would enable incorporation into clinical decision-making. Ultimately, TMEM170B status could become part of a broader molecular profiling approach for cancer patients, contributing to treatment selection and prognosis assessment in precision oncology frameworks.