Golgi feels DNA's pain

Organelle Communication with the Nucleus

Compartmentalization of cellular components is critical to the spatiotemporal and environmental regulation of biochemical activities inside a cell, ensures the proper division of cellular labor and resources, and increases the efficiency of metabolic processes. However, compartmentalization also poses a challenge as organelles often need to communicate across these compartments to complete reaction pathways. These communication signals are often critical aspects of the cellular response to changing environmental conditions. A central signaling hub in the cell, the nucleus communicates with mitochondria, lysosomes, the endoplasmic reticulum, and the Golgi body to ensure optimal organellar and cellular performance. Here we review different mechanisms by which these organelles communicate with the nucleus, focusing on anterograde and retrograde signaling of mitochondria, localization-based signaling of lysosomes, the unfolded protein response of the endoplasmic reticulum, and evidence for nucleus-Golgi signaling. We also include a brief overview of some less well-characterized mechanisms of communication between non-nuclear organelles.

Golgi phosphoprotein 3 induces autophagy and epithelial-mesenchymal transition to promote metastasis in colon cancer

In this study, we aimed to investigate whether and how Golgi phosphoprotein 3 (GOLPH3) facilitates colon cancer metastasis via the regulation of autophagy and epithelial-mesenchymal transition (EMT). The role GOLPH3 plays in colon cancer metastasis was analyzed using western blotting, immunohistochemistry, transwell, wound-healing, and zebrafish assays. Autophagy and EMT were assessed via RNA-sequencing (RNA-seq) analysis, mRFP-GFP-LC3 reporter assays, and their related markers. Significant associations were found between colon cancer clinical and pathological stages and poor prognosis. GOLPH3 facilitates colon cancer metastasis, both in vitro and in vivo. RNA-seq analysis of GOLPH3-overexpressing and control cell models revealed that GOLPH3 enhances EMT and autophagy. Moreover, examination of autophagic, epithelial, and mesenchymal markers in GOLPH3-overexpressing, -silenced, and control cell lines revealed that GOLPH3 promotes EMT and autophagy. When autophagy was inhibited, GOLPH3-promoted metastasis and EMT were counteracted in vitro and in vivo. Using RNA-seq, PI3K/Akt signaling was identified as the key downstream pathway on which GOLPH3 acts. Mechanistically, we demonstrated that GOLPH3 stimulates autophagy and induces EMT via the suppression of the phosphorylation of protein kinase B (Akt) at Ser473. In summary, GOLPH3 induces autophagy and EMT, promoting metastasis in colon cancer. Beyond this, and in contrast to conventional perspectives, we discovered that GOLPH3 represses the phosphorylation of Akt at Ser473.

SPDL1 Is an Independent Predictor of Patient Outcome in Colorectal Cancer

Spindle Apparatus Coiled-Coil Protein 1 (SPDL1) is a relatively recently identified coiled-coil domain containing protein and an important determinant of DNA fidelity by ensuring faithful mitosis. Hence, SPDL1 is suspected to underlie genomic (in-)stability in human cancers, yet its exact roles in these diseases remain largely underexplored. Given that genomic instability (GIN) is a crucial feature in colorectal cancer (CRC), we primarily asked whether the expression of this protein may account for differences in clinicopathological features and survival rates of CRC patients. Protein expression was evaluated by immunohistochemistry in the institutional tissue microarray (TMA), and gene expression by the analysis of publicly available datasets. To place the prognostic relevance in a predicted biological context, gene co-expression set around SPDL1 identified by public data mining was annotated and assessed for enrichment in gene ontology (GO) categories, BRITE hierarchies, and Reactome pathways. The comparison with adjacent normal tissue revealed a high expression of SPDL1 protein in a subset of tumor cases (48.84%), and these had better prognosis than the SPDL1-low expression counterpart even after adjustment for multiple confounders. SPDL1-high expression within tumors was associated with a median 56-month survival advantage, but not with any clinicopathological characteristics of our cohort. In the TCGA cohort, SPDL1 was overexpressed in tumor tissue and positively associated with improved survival, chromosome instability phenotype, and various GIN markers. In addition to the genes critically involved in the cell cycle and mitosis, a gene set co-expressed with SPDL1 contained checkpoint members of both chromosome segregation and DNA replication, as well as those associated with defective DNA repair, and retrograde vesicle-mediated transport. In conclusion, SPDL1 is an independent predictor of CRC patient survival in a possible connection with chromosomal instability.

Akt Is S-Palmitoylated: A New Layer of Regulation for Akt

The protein kinase Akt/PKB participates in a great variety of processes, including translation, cell proliferation and survival, as well as malignant transformation and viral infection. In the last few years, novel Akt posttranslational modifications have been found. However, how these modification patterns affect Akt subcellular localization, target specificity and, in general, function is not thoroughly understood. Here, we postulate and experimentally demonstrate by acyl-biotin exchange (ABE) assay and ³H-palmitate metabolic labeling that Akt is S-palmitoylated, a modification related to protein sorting throughout subcellular membranes. Mutating cysteine 344 into serine blocked Akt S-palmitoylation and diminished its phosphorylation at two key sites, T308 and T450. Particularly, we show that palmitoylation-deficient Akt increases its recruitment to cytoplasmic structures that colocalize with lysosomes, a process stimulated during autophagy. Finally, we found that cysteine 344 in Akt1 is important for proper its function, since Akt1-C344S was unable to support adipocyte cell differentiation in vitro. These results add an unexpected new layer to the already complex Akt molecular code, improving our understanding of cell decision-making mechanisms such as cell survival, differentiation and death.

miR34a/GOLPH3 Axis abrogates Urothelial Bladder Cancer Chemoresistance via Reduced Cancer Stemness

Rationale: Chemoresistance and subsequent recurrence of human urothelial bladder cancer (UBC) is partially driven by a subpopulation of tumor initiating cells, namely cancer stem cells (CSCs). However, the underlying molecular mechanism in chemotherapy-induced CSCs enrichment and following chemoresistance and recurrence remains largely unclear.

Methods: Gemcitabine and cisplatin (GC) chemoresistant cell lines (T24 GC 3^rd and 5637 GC 3^rd cells) and the chemo-sensitive UBC cell lines T24 and 5637 were established in vivo for the investigation of acquired resistance mechanisms. The role of miR34a/GOLPH3 axis in regulating UBC chemoresistance and recurrence was evaluated in cell and animal models. The expression levels of miR34a/GOLPH3 axis and CSCs markers were assayed in specimens of UBC. The association of GOLPH3 with clinicopathologic features and prognosis was analysed.

Results: RT-PCR and western blotting confirmed that the expression levels of miR34a were decreased and GOLPH3 were increased in GC chemoresistant UBC cell lines. Downregulation of miR34a resulted in the overexpression of GOLPH3, which is a target gene of miR34a confirmed by luciferase experiment. The ectopic expression of miR34a decreased the stem cell properties of chemoresistant UBC cells and re-sensitized these cells to GC treatment in vitro and in vivo. Moreover, miR34a/GOLPH3 axis has obvious clinical relevance with prognosis and recurrence in human UBC patients with standard GC chemotherapy.

Conclusion: Our results suggest that miR34a/GOLPH3 axis exert key role in CSCs involved UBC drug resistance and recurrence and warrant further development as a promising therapeutic approach in treating drug-resistant UBC.

Association of GOLPH2 expression with survival in non-small-cell lung cancer: clinical implications and biological validation

AIM

We investigated the role of GOLPH2 in non-small-cell lung cancer (NSCLC).

METHODS

We analyzed the relationship between the expression of GOLPH2 and the clinical pathological characteristics of patients with NSCLC. The function of GOLPH2 in NSCLC cell lines was also explored through overexpression and knockdown studies.

RESULTS

The positive expression rate of GOLPH2 protein in NSCLC tissue was higher than that of normal lung tissue. We found that positive GOLPH2 expression was closely associated with unfavorable features of patients with NSCLC. The GOLPH2 expression was an independent predictor of the prognosis of patients with NSCLC. That GOLPH2 can promote the proliferation and invasion of NSCLC cells.

CONCLUSION

The GOLPH2 is a novel marker for NSCLC.

GOLPH3 links the Golgi, DNA damage, and cancer

GOLPH3 is the first example of an oncogene that functions in secretory trafficking at the Golgi. The discovery of GOLPH3's roles in both cancer and Golgi trafficking raises questions about how GOLPH3 and the Golgi contribute to cancer. Our recent investigation of the regulation of GOLPH3 revealed a surprising response by the Golgi upon DNA damage that is mediated by DNA-PK and GOLPH3. These results provide new insight into the DNA damage response with important implications for understanding the cellular response to standard cancer therapeutic agents.

The DNA-dependent protein kinase: A multifunctional protein kinase with roles in DNA double strand break repair and mitosis

The DNA-dependent protein kinase (DNA-PK) is a serine/threonine protein kinase composed of a large catalytic subunit (DNA-PKcs) and the Ku70/80 heterodimer. Over the past two decades, significant progress has been made in elucidating the role of DNA-PK in non-homologous end joining (NHEJ), the major pathway for repair of ionizing radiation-induced DNA double strand breaks in human cells and recently, additional roles for DNA-PK have been reported. In this review, we will describe the biochemistry, structure and function of DNA-PK, its roles in DNA double strand break repair and its newly described roles in mitosis and other cellular processes.

GOLPH3 high expression predicts poor prognosis in patients with resected non-small cell lung cancer: an immunohistochemical analysis

Golgi phosphoprotein 3 (GOLPH3) has been reported to be involved in the development of several human tumours. However, little is known about GOLPH3 expression and its clinical significance in non-small cell lung cancer (NSCLC). The present study was conducted to investigate the expression of GOLPH3 and its prognostic significance in NSCLC. Immunohistochemical analysis was used to determine the expression of GOLPH3 in 145 cases NSCLC tissue and their corresponding adjacent normal tissues. The results are the following: (1) The GOLPH3 protein was mainly located in the cytoplasm of NSCLC tissue; (2) GOLPH3 was highly expressed in 71.7% of NSCLC tissues versus 22.8% of adjacent tissues (P < 0.01); (3) GOLPH3 expression was significantly associated with tumour-node-metastasis (TNM) stage (P = 0.001), lymph node status (P = 0.014), and degree of differentiation (P = 0.018); (4) The Kaplan-Meier curve indicated that the patients with high GOLPH3 expression had significantly shorter survival than those with low GOLPH3 expression; and (5) Cox regression analysis demonstrated that the expression of GOLPH3, lymph node status, and TNM stage were independent prognostic predictors for NSCLC patients. High GOLPH3 expression is predictive of poor prognosis of NSCLC, implying that GOLPH3 may be a promising new target for targeted therapies for NSCLC.