Expression of TOMM34 and Its Clinicopathological Correlations in Urothelial Carcinoma of the Bladder

PAX translocations remodel mitochondrial metabolism through altered leucine usage in rhabdomyosarcoma

Alveolar rhabdomyosarcoma (ARMS) patients harboring paired-box fusion proteins (PAX3/7-FOXO1) exhibit a greater incidence of tumor relapse, metastasis, and poor survival outcome, thereby underscoring the urgent need to develop effective therapies to treat this subtype of childhood cancer. To uncover mechanisms that contribute to tumor initiation, we develop a muscle progenitor model and use epigenomic approaches to unravel genome rewiring events mediated by PAX3/7 fusion proteins. Among the key targets of PAX3/7 fusion proteins, we identify a cohort of oncogenes, fibroblast growth factor (FGF) receptors, tRNA-modifying enzymes, and genes essential for mitochondrial metabolism and protein translation, which we successfully targeted in preclinical trials. We identify leucine usage as a key factor driving the growth of aggressive PAX-fusion tumors, as limiting its bioavailability impaired oxidative phosphorylation and mitochondrial metabolism, delaying tumor progression and improving survival in vivo. Our data provide a compelling list of actionable targets and suggest promising new strategies to treat this tumor.

TOMM34 serves as a candidate therapeutic target associated with immune cell infiltration in colon cancer

Background

Colon cancer represents one of the most pervasive digestive malignancies worldwide. Translocase of the outer mitochondrial membrane 34 (TOMM34) is considered an oncogene and is implicated in tumor proliferation. However, the correlation between TOMM34 and immune cell infiltration in colon cancer has not been investigated.

Materials and methods

Based on multiple open online databases, we performed integrated bioinformatics analysis of TOMM34 to evaluate the prognostic value of TOMM34 and its correlation with immune cell infiltration.

Results

TOMM34 gene and protein expression levels were elevated in tumor tissues compared with normal tissues. Survival analysis revealed that upregulation of TOMM34 was significantly associated with poorer survival time in colon cancer. High TOMM34 expression was dramatically related to low levels of B cells, CD8+ T cells, neutrophils, dendritic cells, PD-1, PD-L1 and CTLA-4.

Conclusions

Our results confirmed that high expression of TOMM34 in tumor tissue correlates with immune cell infiltration and worse prognosis in colon cancer patients. TOMM34 may serve as a potential prognostic biomarker for colon cancer diagnosis and prognosis prediction.

Exploiting Multi-Omics Profiling and Systems Biology to Investigate Functions of TOMM34

Although modern biology is now in the post-genomic era with vastly increased access to high-quality data, the set of human genes with a known function remains far from complete. This is especially true for hundreds of mitochondria-associated genes, which are under-characterized and lack clear functional annotation. However, with the advent of multi-omics profiling methods coupled with systems biology algorithms, the cellular role of many such genes can be elucidated. Here, we report genes and pathways associated with TOMM34, Translocase of Outer Mitochondrial Membrane, which plays role in the mitochondrial protein import as a part of cytosolic complex together with Hsp70/Hsp90 and is upregulated in various cancers. We identified genes, proteins, and metabolites altered in TOMM34-/- HepG2 cells. To our knowledge, this is the first attempt to study the functional capacity of TOMM34 using a multi-omics strategy. We demonstrate that TOMM34 affects various processes including oxidative phosphorylation, citric acid cycle, metabolism of purine, and several amino acids. Besides the analysis of already known pathways, we utilized de novo network enrichment algorithm to extract novel perturbed subnetworks, thus obtaining evidence that TOMM34 potentially plays role in several other cellular processes, including NOTCH-, MAPK-, and STAT3-signaling. Collectively, our findings provide new insights into TOMM34's cellular functions.

TOMM34 promotes cell proliferation, migration, and invasion of OSCC and modulates mitochondrial function

BACKGROUND

34-kDa translocase of the outer mitochondrial membrane (TOMM34) has been reported highly expressed in many cancers and is positively correlated to poorer prognosis. Our prior study showed TOMM34 is highly expressed in oral squamous cell carcinoma (OSCC) and is closely related to TNM classification and tumor size. TOMM34 is also associated with lymph node metastasis and poorer overall survival and disease-free survival in HPV-negative OSCC.

METHODS

We knocked down TOMM34 in OSCC cells (SCC15, HPV positive; Cal27, HPV negative) with siRNA and over-expressed with plasmids. The effects of TOMM34 on cell proliferation, migration and invasion abilities were detected by EdU assay, CCK-8 assay, wound-healing assay, and Transwell assay. We also detected the mitochondrial morphology and the intracellular Reactive Oxygen Species (ROS) level by fluorescence staining and flow cytometry. Finally, we monitored the protein levels of ERK pathway-related molecules.

RESULTS

TOMM34 knockdown decreased the proliferation in SCC15 and Cal27, and weakened the migration and invasion abilities as well. Mitochondria became shorter, in the shape of dots or short rods, suggesting that mitochondrial damage occurred. Intracellular ROS levels increased significantly after knockdown TOMM34 and decreased after over-expressing TOMM34. The phosphorylation levels of ERK1/2 and MEK1/2 in SCC15 were significantly higher than in Cal27. Besides, the phosphorylation levels of ERK1/2 and MEK1/2 were inhibited in SCC15 after knockdown of TOMM34, but not in Cal27.

CONCLUSION

TOMM34 promotes the cell proliferation, migration, and invasion of OSCC. In addition, TOMM34 participates in maintaining the mitochondrial shape and reducing the intracellular ROS level to protect cancer cells. Furthermore, TOMM34 increases the activity of ERK1/2 and MEK1/2 in HPV-positive OSCC cells but not in HPV-negative.

Disrupting metformin adaptation of liver cancer cells by targeting the TOMM34/ATP5B axis

Metformin, a well-known antidiabetic drug, has been repurposed for cancer treatment; however, recently observed drug resistance and tumor metastasis have questioned its further application. Here, we found that long-term metformin exposure led to metabolic adaptation of hepatocellular carcinoma (HCC) cells, which was characterized by an obvious epithelial-mesenchymal transition (EMT) phenotype and compensatory elevation of oxidative phosphorylation (OXPHOS). TOMM34, a translocase of the outer mitochondrial membrane, was upregulated to promote tumor metastasis in response to metformin-induced metabolic stress. Mechanistically, TOMM34 interacted with ATP5B to preserve F₁ F_O -ATPase activity, which conferred mitochondrial OXPHOS and ATP production. This metabolic preference for OXPHOS suggested a large requirement of energy supply by cancer cells to survive and spread in response to therapeutic stress. Notably, disturbing the interaction between TOMM34 and ATP5B using Gboxin, a specific OXPHOS inhibitor, increased sensitivity to metformin and suppressed tumor progression both in vitro and in vivo. Overall, this study demonstrates a molecular link of the TOMM34/ATP5B-ATP synthesis axis during metformin adaptation and provides promising therapeutic targets for metformin sensitization in cancer treatment.

High Expression of Tomm34 and Its Correlations With Clinicopathology in Oral Squamous Cell Carcinoma

Tomm34, as a member of the outer mitochondrial membrane proteins, is evenly distributed between the cytoplasm and the outer mitochondrial membrane. It is up-regulated in a variety of tumors and correlates with poor prognosis. This study aimed to investigate expression of Tomm34 and its correlations with clinicopathology in oral squamous cell carcinoma (OSCC). Oncomine database and UALCAN database were utilized to predict the expression and prognosis values of Tomm34 in head and neck squamous cell carcinoma (HNSCC). By immunohistochemistry, a retrospective study was performed to verify the bioinformatics results to evaluate the Tomm34 expression and clinicopathological variables in both HPV-positive OSCC and HPV-negative OSCC. Immunohistochemistry of our cohort revealed that 48 cases fulfilled the Tomm34 high expression judgment criteria, and the overall positive rate was 60% (48/80), and 27 cases fulfilled the p16 expression judgment criteria (33.75%, 27/80). The high expression of Tomm34 was closely related with the TNM classification of OSCC (p < 0.01) and tumor size (p < 0.01) both in HPV-negative OSCC and HPV-positive OSCC, while related with lymph node metastasis (p = 0.001) in HPV-negative OSCC and drinking history (p = 0.044) in HPV-positive OSCC. In addition, the Kaplan-Meier curves indicated that higher level of Tomm34 was correlated with poorer overall survival (OS) and disease-free survival (DFS) in HPV-negative OSCC (OS, p = 0.046; DFS, p = 0.020) but not in HPV-positive OSCC (OS, p = 0.824; DFS, p = 0.782). In conclusion, Tomm34 is highly expressed in OSCC and may be a useful factor to provide prognostic information, especially in HPV-negative OSCC group.

Tomm34 is commonly expressed in epithelial ovarian cancer and associates with tumour type and high FIGO stage

Background

Increased activity of the chaperones Hsp70 and Hsp90 is a common feature of solid tumours. Translocase of the outer mitochondrial membrane 34 (Tomm34) is a cochaperone of both Hsp70 and Hsp90 that was found to be overexpressed in colorectal, hepatocellular, lung and breast carcinomas. The expression profile of Tomm34 in ovarian cancer has not been investigated. Therefore, the aim of the current study was to investigate the expression pattern of Tomm34 in ovarian carcinomas and analyse its correlation with clinico-pathological parameters.

Results

Epithelial ovarian cancers (140) were histologically classified based on their morphology and graded into two types comprising 5 histologic subgroups. Type I carcinomas comprise low grade serous (LGSC), clear cell (CCOC) and endometrioid (ENOC), type II comprises high grade serous carcinomas (HGSC) and solid, pseudoendometrioid, transitional carcinomas (SET). Tomm34 was more highly expressed in type II than type I carcinomas (p < 0.0001). Comparing tumours based on the mutation in the TP53 gene revealed similar results, where mutant tumours exhibited significantly higher levels of Tomm34 (p < 0.0001). The decreased levels of Tomm34 in type I carcinomas were particularly evident in clear cell and mucinous carcinomas. The expression of Tomm34 was also positively correlated with FIGO stage (r = 0.23; p = 0.007). Tomm34 levels also indicated poor prognosis for patients with mutant p53.

Conclusions

Our data indicate that Tomm34 is commonly expressed at high levels in epithelial ovarian cancers, except for the clear cell and mucinous subtypes. The expression of Tomm34 corresponds with the dualistic model of ovarian cancer pathogenesis where high grade, type II tumours exhibit higher expression of Tomm34 in contrast to type I tumours. These data are also comparable to the previous findings that Tomm34 is a marker of progression and poor prognosis in human cancer.

Electronic supplementary material

The online version of this article (10.1186/s13048-019-0498-0) contains supplementary material, which is available to authorized users.