PKD1 is downregulated in non-small cell lung cancer and mediates the feedback inhibition of mTORC1-S6K1 axis in response to phorbol ester

Membrane trafficking in breast cancer progression: protein kinase D comes into play

Protein kinase D (PKD) is a serine/threonine kinase family that controls important cellular functions, most notably playing a key role in the secretory pathway at the trans-Golgi network. Aberrant expression of PKD isoforms has been found mainly in breast cancer, where it promotes various cellular processes such as growth, invasion, survival and stem cell maintenance. In this review, we discuss the isoform-specific functions of PKD in breast cancer progression, with a particular focus on how the PKD controlled cellular processes might be linked to deregulated membrane trafficking and secretion. We further highlight the challenges of a therapeutic approach targeting PKD to prevent breast cancer progression.

The p70S6K/PI3K/MAPK feedback loop releases the inhibition effect of high-dose rapamycin on rat mesangial cell proliferation

Glomerular mesangial cell (MC) proliferation is one of the causative factors of glomerular diseases and one of their prominent pathological features. Rapamycin can inhibit MC proliferation and slow the progression to chronic renal fibrosis. The present study was designed to observe the role of rapamycin in MC proliferation and to explore the mechanism by which rapamycin acts on Akt and MAPK/ERK1/2 pathways in mesangial cells. MTT assay and flow cytometry were used to evaluate the proliferation and the cell cycle phase of glomerular mesangial cells respectively. The mRNA expression level of p70S6K was detected by RT-qPCR. Western blotting was performed to determine p70S6K, PI3K/Akt, and PI3K/MAPK protein expression. We found that rapamycin could reduce mesangial cell proliferation and arrest the cell cycle in the G1 phase, however the inhibition effect of 1000 nmol/L rapamycin was not higher than that in the 100 nmol/L group. The results of western blotting showed that 1000 nmol/L rapamycin more significantly inhibited the phosphorylation of p70S6K than 100 nmol/L, suggesting there should be another signaling pathway that activates the proliferation of MCs. Moreover, our results revealed that 1000 nmol/L rapamycin led to Raf1-MEK1/2-ERK pathway activation through a p70S6K-PI3K-mediated feedback loop in MCs. This study demonstrated that high-dose rapamycin leads to ERK1/2 activation through a p70S6K/PI3K/MAPK feedback loop in rat MCs, thus reducing the inhibitory effect of rapamycin on MC proliferation.

Multifaceted Functions of Protein Kinase D in Pathological Processes and Human Diseases

Protein kinase D (PKD) is a family of serine/threonine protein kinases operating in the signaling network of the second messenger diacylglycerol. The three family members, PKD1, PKD2, and PKD3, are activated by a variety of extracellular stimuli and transduce cell signals affecting many aspects of basic cell functions including secretion, migration, proliferation, survival, angiogenesis, and immune response. Dysregulation of PKD in expression and activity has been detected in many human diseases. Further loss- or gain-of-function studies at cellular levels and in animal models provide strong support for crucial roles of PKD in many pathological conditions, including cancer, metabolic disorders, cardiac diseases, central nervous system disorders, inflammatory diseases, and immune dysregulation. Complexity in enzymatic regulation and function is evident as PKD isoforms may act differently in different biological systems and disease models, and understanding the molecular mechanisms underlying these differences and their biological significance in vivo is essential for the development of safer and more effective PKD-targeted therapies. In this review, to provide a global understanding of PKD function, we present an overview of the PKD family in several major human diseases with more focus on cancer-associated biological processes.

IGF1R and MAPK15 Emerge as Potential Targets of Pentabromobenzylisothioureas in Lung Neuroendocrine Neoplasms

Pentabromobenzylisothioureas are antitumor agents with diverse properties, including the inhibition of MAPK15, IGF1R and PKD1 kinases. Their dysregulation has been implicated in the pathogenesis of several cancers, including bronchopulmonary neuroendocrine neoplasms (BP-NEN). The present study assesses the antitumor potential of ZKKs, a series of pentabromobenzylisothioureas, on the growth of the lung carcinoid H727 cell line. It also evaluates the expression of MAPK15, IGF1R and PKD1 kinases in different BP-NENs. The viability of the H727 cell line was assessed by colorimetric MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide) and its proliferation by BrdU (5-bromo-2′-deoxyuridine) assay. Tissue kinase expression was measured using TaqMan-based RT-PCR and immunohistochemistry. ZKKs (10⁻⁴ to 10⁻⁵ M) strongly inhibited H727 cell viability and proliferation and their antineoplastic effects correlated with their concentrations (p < 0.001). IGF1R and MAPK15 were expressed at high levels in all subtypes of BP-NENs. In addition, the SCLC (small cell lung carcinoma) patients demonstrated higher mRNA levels of IGF1R (p = 0.010) and MAPK15 (p = 0.040) than the other BP-NEN groups. BP-NENs were characterized by low PKD1 expression, and lung neuroendocrine cancers demonstrated lower PKD1 mRNA levels than carcinoids (p = 0.003). ZKKs may suppress BP-NEN growth by inhibiting protein kinase activity. Our results suggest also a possible link between high IGF1R and MAPK15 expression and the aggressive phenotype of BP-NEN tumors.

Protein Kinase D1 Is Increased in Tumor Tissue, Correlates With Advanced Tumor Features and Worse Prognosis of Non-Small Cell Lung Cancer

OBJECTIVE

This study aimed to assess protein kinase D1 expression and its association with tumor characteristics as well as prognosis in patients with non-small cell lung cancer.

METHODS

Protein kinase D1 expression in tumor tissues and adjacent tissues from 172 patients with non-small cell lung cancer who underwent surgical resection were analyzed by immunohistochemical staining. Based on the total immunohistochemical score, protein kinase D1 expression was classified as protein kinase D1 high expression (further divided into protein kinase D1 high+++, protein kinase D1 high++, and protein kinase D1 high+ expressions) and protein kinase D1 low expression. Clinical characteristics of patients with non-small cell lung cancer were acquired from the database. Accumulating disease-free survival and overall survival were calculated based on patients' relapse/survival status.

RESULTS

Protein kinase D1 expression was increased in tumor tissues compared to adjacent tissues (P < .001). Tumor protein kinase D1 high expression correlated with poorer pathological differentiation (P = .041), increased tumor size (P = .003), the presence of lymph node metastasis (P = .001), and elevated tumor, nodes and metastases stage (P < .001). Besides, both accumulating disease-free survival and overall survival were decreased in patients with tumor protein kinase D1 high expression compared to patients with tumor protein kinase D1 low expression (P = .010 for disease-free survival and P = 0.005 for overall survival). Moreover, they were lowest in patients with tumor protein kinase D1 high+++ expression, followed by patients with tumor protein kinase D1 high++ expression, then patients with tumor protein kinase D1 high+ expression, and highest in patients with tumor protein kinase D1 low expression (P < .001 for disease-free survival and P = .001 for overall survival). Notably, higher tumor protein kinase D1 expression was an independent predictive factor for decreased disease-free survival (P = .001) and overall survival (P = .004).

CONCLUSIONS

Protein kinase D1 might be a potential marker to identify patients with non-small cell lung cancer with worse tumor features and prognosis.

Deciphering the Role of Protein Kinase D1 (PKD1) in Cellular Proliferation

Protein kinase D1 (PKD1) is a serine/threonine kinase that belongs to the calcium/calmodulin-dependent kinase family, and is involved in multiple mechanisms implicated in tumor progression such as cell motility, invasion, proliferation, protein transport, and apoptosis. While it is expressed in most tissues in the normal state, PKD1 expression may increase or decrease during tumorigenesis, and its role in proliferation is context-dependent and poorly understood. In this review, we present and discuss the current landscape of studies investigating the role of PKD1 in the proliferation of both cancerous and normal cells. Indeed, as a potential therapeutic target, deciphering whether PKD1 exerts a pro- or antiproliferative effect, and under what conditions, is of paramount importance.

MicroRNA-4286 promotes cell proliferation, migration, and invasion via PTEN regulation of the PI3K/Akt pathway in non-small cell lung cancer

It is well-known that phosphatase and tensin homologue deleted on chromosome 10 (PTEN) is a tumor suppressor which negatively regulates PI3K/AKT signaling and is activated widely in non-small cell lung cancers (NSCLC). However, genetic alterations in PTEN genes are rare, suggesting an undefined mechanism(s) for their suppression. Notably, growing evidence indicates that PTEN can be regulated by microRNAs involved in cancer progression. In this study, we discover that the miR-4286 is overexpressed in NSCLC and negatively regulates the expression of PTEN. Furthermore, we found that miR-4286 reduces PTEN expression by directly binding to PTEN 3'-untranslated region (UTR), thereby inhibiting NSCLC cell proliferation and mobility. Moreover, mechanistic investigations revealed that miR-4286 overexpression was a result of PTEN-mediated activation of the PI3K/AKT pathway. Taken together, our findings elucidate that miR-4286 promotes the tumorigenesis of NSCLC by interacting with PTEN. This miR-4286-mediated upregulation of PTEN might lead to new therapeutic strategies for NSCLC.

Prognostic Effect of TP53 and PKD Co-Mutations in Patients with Resected Epidermal Growth Factor Receptor-Mutated Lung Adenocarcinoma

BACKGROUND

The impact of specific co-mutations in epidermal growth factor receptor (EGFR)-mutated lung adenocarcinoma is unclear.

METHODS

Tissues from 147 consecutive patients with resected EGFR-mutated lung adenocarcinomas treated at Sun Yat-Sen University Cancer Center were analyzed by next-generation sequencing (NGS). Associations between mutation status, patient baseline characteristics, and survival outcomes (disease-free survival [DFS] and overall survival [OS]) after surgical resection were analyzed.

RESULTS

TP53 and protein kinase D (PKD) mutations were the two most frequently observed co-mutations in this cohort. Dual PKD/EGFR and TP53/EGFR mutations were found in 39 (27%) and 72 patients (49%), respectively, with dual TP53/EGFR mutations more commonly observed in male patients (P = 0.021). Both TP53 (hazard ratio [HR] 2.08, 95% confidence interval [CI] 1.23-3.54, P = 0.007) and PKD co-mutations (HR 1.72, 95% CI 1.01-2.93, P = 0.044) were associated with shorter DFS, but not OS, in univariate analysis. In multivariate analysis, patients harboring PKD/TP53 co-mutations had shorter DFS compared with PKD^-/TP53^- cases (HR 2.49, 95% CI 1.15-5.37, P = 0.02). In a subgroup of never-smokers, TP53 co-mutations were associated with significantly worse OS (HR 50.11, 95% CI 2.39-1049.83, P = 0.012).

CONCLUSION

TP53 and PKD mutations were the two most frequently observed co-mutations in resected EGFR-mutated lung adenocarcinoma. Both mutations were associated with poorer prognoses in affected patients.

High PKD2 predicts poor prognosis in lung adenocarcinoma via promoting Epithelial-mesenchymal Transition

Protein kinase D2 (PKD2) has been reported to be related with progression and invasion in various cancers. However, its prognostic value and the underlying mechanism in lung cancer remains unclear. Herein we evaluated the expression of PKD2 in lung adenocarcinoma and investigated its relationship with EMT. GSEA, TCGA and K-M plotter database were applied and revealed that high PKD2 expression predicted poor outcome and related with lymph nodes metastasis in lung cancer. IHC and qRT-PCR were performed and found PKD2 was elevated in lung adenocarcinoma and negatively related with OS (p = 0.015), PFS (p = 0.006) and the level of E-cadherin (p = 0.021). Experiment in lung adenocarcinoma cell lines demonstrated up-regulation of PKD2 led to high expression of mesenchymal markers (N-cadherin, vim, mmp9 et al.) and EMT transcription factors(zeb1, twist, snail), and the results were reversed when PKD2 was knocked down. Further investigation showed that abrogation of PKD2 inhibited A549 cell migration, invasion, proliferation and induced cell arrest in G2/M phase. We concluded that high expression of PKD2 was associated with poor prognosis and cancer progression in lung adenocarcinoma patients by promoting EMT.

Paternal programming of breast cancer risk in daughters in a rat model: opposing effects of animal- and plant-based high-fat diets

Background

Although males contribute half of the embryo’s genome, only recently has interest begun to be directed toward the potential impact of paternal experiences on the health of offspring. While there is evidence that paternal malnutrition may increase offspring susceptibility to metabolic diseases, the influence of paternal factors on a daughter’s breast cancer risk has been examined in few studies.

Methods

Male Sprague-Dawley rats were fed, before and during puberty, either a lard-based (high in saturated fats) or a corn oil-based (high in n-6 polyunsaturated fats) high-fat diet (60 % of fat-derived energy). Control animals were fed an AIN-93G control diet (16 % of fat-derived energy). Their 50-day-old female offspring fed only a commercial diet were subjected to the classical model of mammary carcinogenesis based on 7,12-dimethylbenz[a]anthracene initiation, and mammary tumor development was evaluated. Sperm cells and mammary gland tissue were subjected to cellular and molecular analysis.

Results

Compared with female offspring of control diet-fed male rats, offspring of lard-fed male rats did not differ in tumor latency, growth, or multiplicity. However, female offspring of lard-fed male rats had increased elongation of the mammary epithelial tree, number of terminal end buds, and tumor incidence compared with both female offspring of control diet-fed and corn oil-fed male rats. Compared with female offspring of control diet-fed male rats, female offspring of corn oil-fed male rats showed decreased tumor growth but no difference regarding tumor incidence, latency, or multiplicity. Additionally, female offspring of corn oil-fed male rats had longer tumor latency as well as decreased tumor growth and multiplicity compared with female offspring of lard-fed male rats. Paternal consumption of animal- or plant-based high-fat diets elicited opposing effects, with lard rich in saturated fatty acids increasing breast cancer risk in offspring and corn oil rich in n-6 polyunsaturated fatty acids decreasing it. These effects could be linked to alterations in microRNA expression in fathers’ sperm and their daughters’ mammary glands, and to modifications in breast cancer-related protein expression in this tissue.

Conclusions

Our findings highlight the importance of paternal nutrition in affecting future generations’ risk of developing breast cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-016-0729-x) contains supplementary material, which is available to authorized users.

mTOR controls lysosome tubulation and antigen presentation in macrophages and dendritic cells

Macrophages and dendritic cells exposed to lipopolysaccharide (LPS) convert their lysosomes from small, punctate organelles into a network of tubules. Tubular lysosomes have been implicated in phagosome maturation, retention of fluid phase, and antigen presentation. There is a growing appreciation that lysosomes act as sensors of stress and the metabolic state of the cell through the kinase mTOR. Here we show that LPS stimulates mTOR and that mTOR is required for LPS-induced lysosome tubulation and secretion of major histocompatibility complex II in macrophages and dendritic cells. Specifically, we show that the canonical phosphatidylinositol 3-kinase-Akt-mTOR signaling pathway regulates LPS-induced lysosome tubulation independently of IRAK1/4 and TBK. Of note, we find that LPS treatment augmented the levels of membrane-associated Arl8b, a lysosomal GTPase required for tubulation that promotes kinesin-dependent lysosome movement to the cell periphery, in an mTOR-dependent manner. This suggests that mTOR may interface with the Arl8b-kinesin machinery. To further support this notion, we show that mTOR antagonists can block outward movement of lysosomes in cells treated with acetate but have no effect in retrograde movement upon acetate removal. Overall our work provides tantalizing evidence that mTOR plays a role in controlling lysosome morphology and trafficking by modulating microtubule-based motor activity in leukocytes.