Adipophilin as prognostic biomarker in clear cell renal cell carcinoma

Plin2 inhibits autophagy via activating AKT/mTOR pathway in non-small cell lung cancer

Perilipin 2 (Plin2) is known to be dysregulated in several human malignancies, which facilitates cancer progression. Recent studies have found that the abnormal expression of Plin2 is associated with poor prognosis of non-small cell lung cancer (NSCLC). However, the specific role of Plin2 and its underlying mechanism remain unclear. This study revealed that Plin2 expression was low in NSCLC tissues, and its relatively higher expression indicated larger tumor size and poorer prognosis. In vitro experiments proved that Plin2 promoted NSCLC cellular proliferation and inhibited autophagy by activating the AKT/mTOR pathway. Meanwhile, treatment with the AKT phosphorylation promoter or inhibitor neutralized the influence of Plin2 depletion or over-expression on proliferation and autophagy, respectively. In vivo study showed that Plin2 stimulated subcutaneous tumorigenesis of NSCLC cells in nude mice. Collectively, this study clarified the carcinogenic role of Plin2 and its molecular mechanism in NSCLC progression, which may facilitate a targeted therapy in the future.

Challenges in Pharmacological Intervention in Perilipins (PLINs) to Modulate Lipid Droplet Dynamics in Obesity and Cancer

Perilipins (PLINs) are the most abundant proteins in lipid droplets (LD). These LD-associated proteins are responsible for upgrading LD from inert lipid storage structures to fully functional organelles, fundamentally integrated in the lipid metabolism. There are five distinct perilipins (PLIN1-5), each with specific expression patterns and metabolic activation, but all capable of regulating the activity of lipases on LD. This plurality creates a complex orchestrated mechanism that is directly related to the healthy balance between lipogenesis and lipolysis. Given the essential role of PLINs in the modulation of the lipid metabolism, these proteins can become interesting targets for the treatment of lipid-associated diseases. Since reprogrammed lipid metabolism is a recognized cancer hallmark, and obesity is a known risk factor for cancer and other comorbidities, the modulation of PLINs could either improve existing treatments or create new opportunities for the treatment of these diseases. Even though PLINs have not been, so far, directly considered for pharmacological interventions, there are many established drugs that can modulate PLINs activity. Therefore, the aim of this study is to assess the involvement of PLINs in diseases related to lipid metabolism dysregulation and whether PLINs can be viewed as potential therapeutic targets for cancer and obesity.

Prognostic implications of the immunohistochemical expression of perilipin 1 and adipophilin in high-grade liposarcoma

AIMS

Liposarcoma is a malignant soft tissue tumour with adipocytic differentiation. Dedifferentiated liposarcoma (DDLS) and myxoid liposarcoma (MLS) are classified as high-grade liposarcomas. Lipid droplet-associated protein (also known as perilipin 1 (PLIN1)) is the predominant perilipin and has utility as a specific marker of adipogenic differentiation. Adipose differentiation-related protein (also known as adipophilin (ADRP)) is ubiquitously expressed in a range of tissues. High ADRP expression is reportedly a poor prognostic factor in several cancer types. However, no previous studies have examined the association between PLIN1 or ADRP expression and prognosis in sarcoma. This study therefore aimed to evaluate the association between PLIN1 or ADRP expression and prognosis in liposarcoma.

METHODS

In total, 97 primary resection specimens (53 MLS and 44 DDLS) were examined in this study. PLIN1 and ADRP expression was evaluated by immunohistochemistry. Survival analyses were performed for MLS and DDLS.

RESULTS

Of the 53 MLS specimens, 15 (28.3%) exhibited high PLIN1 expression. PLIN1 expression was not observed in DDLS specimens. High PLIN1 expression was significantly associated with increased disease-free survival (DFS) among patients with MLS (p=0.045). Distinct ADRP expression was observed in 13 of 53 (24.5%) MLS specimens and 5 of 44 (11.4%) DDLS specimens. High ADRP expression was associated with shorter overall survival (OS) in MLS (p=0.042) and DFS and shorter OS in DDLS (p=0.024 and p<0.001, respectively).

CONCLUSIONS

PLIN1 and ADRP expression is associated with poor prognosis in high-grade liposarcoma.

Adipophilin: roles in physiology and pathology

Adipophilin (ADRP/ADPH/PLIN2), an adipocyte differentiation-related protein, is highly expressed at a very early time during the differentiation of adipocytes. It assists in the formation and maintenance of intracellular lipid droplets and plays a role in regulating the physiological functions of the body. More and more studies indicate that it is involved in the occurrence and development of a variety of glycolipid metabolic diseases and tumours. In this review, we comprehensively stated the expression and functions of adipophilin and introduced its roles in physiology and pathology.

Perilipins at a glance

Lipid droplets (LDs) are ubiquitous organelles that store and supply lipids for energy metabolism, membrane synthesis and production of lipid-derived signaling molecules. While compositional differences in the phospholipid monolayer or neutral lipid core of LDs impact their metabolism and function, the proteome of LDs has emerged as a major influencer in all aspects of LD biology. The perilipins (PLINs) are the most studied and abundant proteins residing on the LD surface. This Cell Science at a Glance and the accompanying poster summarize our current knowledge of the common and unique features of the mammalian PLIN family of proteins, the mechanisms through which they affect cell metabolism and signaling, and their links to disease.

Expression status and prognostic value of the perilipin family of genes in breast cancer

BACKGROUND

The Perilipin (PLIN) family of genes were previously shown to be involved in the formation and degradation of Lipid Droplets (LDs). In addition, they may play important roles in the development and progression of breast cancer. However, the prognostic value of PLIN family members in breast cancer patients remains unclear.

METHODS

Mutations and copy number alterations of PLIN family genes in breast cancer were examined using the cBioportal for Cancer Genomics. In addition, the expression patterns of PLIN family genes were explored using the UCSC Xena online tool. Finally, the Kaplan-Meier Plotter was used to investigate the prognostic value of PLIN family genes in breast cancer.

RESULTS

The findings revealed a low frequency of genetic alterations and amplification was the most frequent change in the PLIN family genes. Additionally, there was an increase in the expression of Perilipin 3 (PLIN3) in breast cancer tissues compared to normal breast tissues. However, expression of the other genes in the PLIN family was significantly lower in breast cancer tissues compared to normal breast tissues. Moreover, there was an increase in the expression levels of Perilipin 1 (PLIN1), PLIN3, Perilipin 4 (PLIN4) and Perilipin 5 (PLIN5) in the luminal A and luminal B subgroups. On the other hand, the expression of Perilipin 2 (PLIN2) was elevated in the human epidermal growth factor receptor 2 (HER2) positive and basal-like subgroups. Furthermore, Kaplan-Meier Plotter analysis demonstrated that high expression of PLIN1 might predict a longer Overall Survival (OS) in patients with breast cancer while overexpression of PLIN2 indicated poor OS of breast cancer patients.

CONCLUSION

The findings from this study indicated that genes in the PLIN family were aberrantly expressed in breast cancer and may serve as novel therapeutic targets as well as prognostic biomarkers for the disease.

Comparison of adipophilin and recently introduced PReferentially expressed Antigen in MElanoma immunohistochemistry in the assessment of sebaceous neoplasms: A pilot study

BACKGROUND

We and others have noticed consistent staining of sebaceous glands with PReferentially expressed Antigen in MElanoma (PRAME). We aimed to determine whether PRAME was as sensitive, specific, and interpretable as adipophilin for distinguishing sebaceous neoplasms (SNs) from other neoplasms.

METHODS

Twenty SNs and 32 control cases were stained for PRAME and adipophilin. Extent of staining was scored as follows: 0, no staining; 1, <5% positivity; 2, 5% to 50% positivity; and 3, >50% positivity. Intensity was scored as negative, weak, moderate, or strong. A composite score was determined by adding the scores for extent and intensity.

RESULTS

PRAME had positive composite scores in all 20 SNs in the more differentiated areas, whereas adipophilin had positive composite scores in 19/20 cases. PRAME showed positivity in the basaloid cells in 15/16 cases, whereas adipophilin was positive in 14. Among controls, PRAME and adipophilin had positive composite scores in 3/32 cases and 6/32 cases, respectively.

CONCLUSIONS

PRAME and adipophilin are comparable in terms of distribution and intensity for staining sebocytes. In the basaloid cells, PRAME expression is often more diffuse and easier to detect than adipophilin. In comparing the SNs to the controls, PRAME was more sensitive and more specific than adipophilin. PRAME could be used as an additional marker of sebaceous differentiation in everyday practice.

Clinicopathological and Molecular Characteristics of Macroscopically Yellowish-Colored Chromophobe Renal Cell Carcinoma Compared to Non-Yellowish-Colored Chromophobe Renal Cell Carcinoma

Each histological variant of renal cell tumors has a unique color. The yellowish color of clear cell renal cell carcinoma (CCRCC) is explained by the presence of intracytoplasmic lipid and glycogen accumulation. Color changes in CCRCC are correlated with clinicopathological and metabolic changes, as well as biological behavior. We analyzed and compared the clinical, histopathological, and immunohistochemical features and gene expression profiles, in lipid metabolism of yellowish-colored ChRCC (ChRCC-Y), non-yellowish-colored ChRCC (ChRCC-N), and CCRCC. Of 14 ChRCCs, we retrieved 6 ChRCC-Ys. Patients with ChRCC-Y are younger than those with ChRCC-N, and the tumor is not predominant in males. ChRCC-Ys are smaller than ChRRC-Ns. Three ChRCC-Ys exhibited individual discrete tubule formation. No ChRCC-Ns exhibited individual discrete tubule formation. Two of 6 ChRCC-Ys showed relatively diffuse adipophilin positivity. No ChRCC-Ns demonstrated diffuse positivity for adipophilin. The expression of SCD, FDFT1, and E2F1 showed a tendency to be lower in ChRCC-Y than in ChRCC-N. The expression of PDGFB showed a tendency to be higher in ChRCC-Y than in ChRCC-N. This study demonstrated ChRCC-Y did not indicate an increase in lipid and cholesterol metabolism and that ChRCC-Y did not have the common molecular alteration of CCRCC. The absence of such metabolic acceleration in ChRCC-Y might support the biological indolent behavior. Furthermore, we revealed that macroscopic color changes might be correlated with various clinicopathological features and immunohistochemical and molecular changes from different perspectives. We believe further characterization of RCC, including tumor heterogeneity, is needed to improve the management of patients with RCC.

The Diagnostic and Prognostic Roles of Combined Expression of Novel Biomarkers in Lung Adenocarcinoma and Lung Squamous Cell Carcinoma: An Immunohistochemical Study

Background & Objective:

Diagnosis and discrimination of lung adenocarcinoma (LUAD) from lung squamous cell carcinoma (LUSC) is critical to select the appropriate treatment regimen as recently targeted therapies require accurate subtyping of nonsmall-cell lung carcinoma (NSCLCs). There are currently several biomarkers that could be used for differentiation between LUAD and LUSC, but they have less sensitivity, specificity, and clinical applicability. The aim of this study was to assess the diagnostic and prognostic values of CLCA2, SPATS2, ST6GALNAC1, and Adipophilin tissue expression in the tissues retrieved from LUAD and LUSC patients using immunohistochemistry.

Methods:

The current study was performed on the samples retrieved from sixty primary lung masses that were diagnosed as LUAD and LUSC. Immunohistochemistry was performed by using a panel of CLCA2, SPATS2, and ST6GALNAC1. We assessed the diagnostic roles of the studied markers in the discrimination between LUAD and LUSC and their prognostic values.

Results:

SPATS2 and CLCA2 were expressed higher in LUSC than LUAD. ST6GALNAC1 and Adipophilin showed higher expression in LUAD than LUSC (P<0.001). The sensitivity and specificity of CLCA2, SPATS2, ST6GALNAC1 and Adipophilin in adequate subtyping and reaching the accurate diagnosis was 100%. We found only significant difference in survival rate between the patients with negative and positive CLCA2 expression (P=0.038 and P=0.019, respectively).

Conclusion:

The combination of biomarkers of CLCA2, SPATS2, ST6GALNAC1, and Adipophilin may lead to an appropriate subtyping of lung cancer and reaching accurate diagnosis with the highest sensitivity and specificity.

ADFP promotes cell proliferation in lung adenocarcinoma via Akt phosphorylation

Previously, we identified differentially expressed proteins, including ADFP, between lung adenocarcinoma (LAC) tissue and paired normal bronchioloalveolar epithelium. In this study, we investigated the role of ADFP in LAC. ADFP levels in the serum of patients with lung cancer and benign diseases were measured by enzyme‐linked immunosorbent assays (ELISA). shRNA was used to knock‐down or overexpress ADFP in A549 and NCI‐H1299 cells. The biological function of ADFP and its underlying mechanisms was evaluated in vivo and in vitro. ADFP was highly expressed in the serum of lung cancer patients, especially those with LAC. ADFP promoted cell proliferation and up‐regulated the p‐Akt/Akt ratio in A549 and NCI‐H1299 cells in vitro. Furthermore, in nude mice, ADFP promoted tumour formation with high levels of p‐Akt/Akt, Ki67 and proliferating cell nuclear antigen (PCNA). Similar to the effect of ADFP knock‐down, MK‐2206 (a phosphorylation inhibitor of Akt) reduced A549 and NCI‐H1299 cell proliferation. In ADFP‐overexpressing A549 and NCI‐H1299 cells, proliferation was suppressed by MK‐2206 and returned to the control level. ADFP did not regulate invasion, migration or adhesion in LAC cells. Together, these results suggest that ADFP promotes LAC cell proliferation in vitro and in vivo by increasing Akt phosphorylation level.

Gene and immunohistochemical expression of HIF-1α, GLUT-1, FASN, and adipophilin in carcinoma ex pleomorphic adenoma development

OBJECTIVE

To analyze the gene and immunohistochemical expression of HIF-1α, GLUT-1, FASN, and adipophilin in normal salivary gland (NSG), pleomorphic adenoma (PA), and carcinoma ex pleomorphic adenoma (CXPA) samples.

MATERIAL AND METHODS

The gene expression was investigated by the real-time PCR (qRT-PCR) method in 9 samples of frozen tissues of normal salivary gland, 13 PA, and 10 CXPA. We validated the reactions by immunohistochemistry on 20 samples from NSG, 85 PA, and 44 CXPA.

RESULTS

Our results showed that there was no statistically significant difference in HIF-1α gene and immunohistochemistry expression among the tissues studied while FASN gene and immunohistochemistry expression increased along the carcinogenesis of the PA. GLUT-1 was significantly more expressed in tumor tissues (PA and CXPA), although protein is mainly expressed in transformed cells than in PA and NSG. In contrast, adipophilin was significantly more expressed in NSG while the expression of the protein increased in PA and CXPA.

CONCLUSIONS

In summary, the data presented here suggest that neoplastic cells reprogram the expression of GLUT-1 and adipophilin to adapt to the tumor microenvironment and reinforce, through immunohistochemical results, a possible transcriptional and post-translational regulatory mechanisms that act on the expression of these genes.

PLIN2 Functions As a Novel Link Between Progesterone Signaling and Metabolism in Uterine Leiomyoma Cells

CONTEXT

Uterine leiomyoma (fibroids) are the most common tumors in women. Recently, perilipin-2 (PLIN2) was identified as a critical target gene of the progesterone receptor; however, its function in the pathogenesis of fibroids is unknown.

OBJECTIVE

To determine the function of PLIN2 in leiomyoma cells.

DESIGN

Tissue and primary cells from leiomyoma and myometrium were analyzed. PLIN2 function in leiomyoma was assessed using small interfering RNA. RNA-sequencing was performed to identify genome-wide effects of PLIN2 depletion. Metabolic activity was measured using the Seahorse XF96 analyzer. Real-time quantitative PCR and immunoblotting were also performed.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

Forty-one premenopausal women undergoing surgery for fibroids.

MAIN OUTCOME MEASURES

Gene expression, oxygen consumption rate (OCR), extracellular acidification rate (ECAR), and cell proliferation.

RESULTS

PLIN2 gene expression was 2.4-fold lower in leiomyoma compared with adjacent myometrium, suggesting a link between PLIN2 deficiency and fibroids. A total of 3877 genes were differentially expressed after PLIN2 knockdown. Gene ontology analysis identified metabolism as the second-highest biological process affected by PLIN2 depletion. OCR (mitochondrial respiration) and ECAR (glycolysis) were significantly upregulated after PLIN2 knockdown; PLIN2-depleted cells had a greater basal metabolic activity and higher metabolic stress response. Cell proliferation was also significantly increased after PLIN2 knockdown.

CONCLUSIONS

PLIN2 depletion increases mitochondrial respiration and glycolysis, suggesting that PLIN2 is a critical regulator of metabolic function in leiomyoma cells. PLIN2 deficiency also reprograms leiomyoma cells to a proproliferative phenotype. These findings introduce metabolomics as an area to explore to better understand leiomyoma tumorigenesis.

Adipophilin expression is an indicator of poor prognosis in patients with pancreatic ductal adenocarcinoma: An immunohistochemical analysis

OBJECTIVE

Adipophilin is a lipid droplet-associated protein, and its expression has been correlated with aggressive clinical behavior in some types of carcinomas, though its role in pancreatic ductal adenocarcinoma (PDAC) has not been clarified. This study aimed to evaluate the role of adipophilin in PDAC.

METHODS

By immunohistochemical staining using tissue microarrays, we analyzed the expression profiles of adipophilin in 181 consecutive PDAC patients who underwent macroscopic margin-negative resection from January 2008 to December 2015. Overall survival (OS) and recurrence-free survival (RFS) were compared based on adipophilin expression, and the risk factors for OS, RFS, and early recurrence (within 6 months) were analyzed.

RESULTS

Of the 181 evaluated patients, 51 (28.2%) were positive for adipophilin expression. A histopathological grade of 3 (p = 0.0012), higher CA19-9 level (p = 0.0016), and R1 status (p = 0.028) were significantly associated with adipophilin-positive patients who had significantly poor OS and RFS compared to those associated with adipophilin-negative patients (p = 0.0007 and p = 0.0022, respectively). They also showed a significantly higher incidence of early recurrence (p = 0.030), based on multivariate analyses.

CONCLUSIONS

Adipophilin is a potential independent prognostic marker for PDAC.

Urinary aquaporin 1 and perilipin 2: Can these novel markers accurately characterize small renal masses and help guide patient management?

OBJECTIVE

To evaluate the role of urine aquaporin 1 and perilipin 2 as biomarkers adjunct to renal mass biopsy in guiding the management of patients with small renal masses.

METHODS

Preoperative aquaporin 1 and perilipin 2 levels in 57 patients with small renal masses undergoing partial nephrectomy were analyzed and compared with postoperative tumor histology. An algorithm was created utilizing aquaporin 1 and perilipin 2 in conjunction with renal mass biopsy. Cut-off values were implemented to maximize biomarker sensitivity and specificity. Renal mass biopsy utilization and intervention were then compared with rates in traditional renal mass biopsy algorithms.

RESULTS

All clear cell and papillary renal cell carcinomas were correctly identified and assigned to the treatment path. All benign lesions were correctly sorted to a confirmatory renal mass biopsy path. Two chromophobe masses did not have elevated aquaporin 1 and perilipin 2, and would require renal mass biopsy. Compared with protocols that call for all small renal masses to be biopsied, confirmatory renal mass biopsy could have been safely avoided in 74% of patients with elevated aquaporin 1 and perilipin 2. Compared with protocols that do not utilize renal mass biopsy, surgical intervention would have been avoided in 23% of patients with benign masses.

CONCLUSIONS

Aquaporin 1 and perilipin 2 possess high sensitivity and specificity for detecting clear cell and papillary renal cell carcinoma. Use of these markers might compliment renal mass biopsy in the characterization of small renal masses.

PLIN3 is up-regulated and correlates with poor prognosis in clear cell renal cell carcinoma

BACKGROUND

PLIN3, one of the members of the perilipin family, has been reported to be involved in the formation and accumulation of lipid droplets. However, the expression levels and diagnostic and prognostic value of PLIN3 in renal cell carcinoma (RCC) remain unclear.

METHODS

Bioinformatic analysis was used to assess the levels of PLIN3 and the correlation between PLIN3 levels and clinicopathological parameters in renal cancer. The expression levels of PLIN3 were determined in human RCC tissues and cell lines by western blot, immunofluorescence and immunohistochemistry assays. Receiver operating characteristic curves and Kaplan-Meier curves were used to analyze the diagnostic and prognostic significance of PLIN3 in RCC.

RESULTS

The expression level of PLIN3 was elevated in RCC tissues and cell lines, which was consistent with the analysis of the TCGA and Oncomine cancer database. The receiver operating characteristic curve indicated that high PLIN3 expression can distinguish cancer tissues from normal kidney tissues (area under the curve = 0.7270, P<0.0001). Kaplan-Meier curves revealed that elevated PLIN3 predicted poor disease-free survival and overall survival.

CONCLUSIONS

PLIN3 is highly expressed in kidney cancer, and high expression of PLIN3 can serve as a useful diagnostic and prognostic biomarker. PLIN3 functional inhibition can be used as a new clinical treatment option.

The Expression of Adipophilin Is Frequently Found in Solid Subtype Adenocarcinoma and Is Associated with Adverse Outcomes in Lung Adenocarcinoma

BACKGROUND

The up-regulation of the lipogenic pathway has been reported in many types of malignant tumors. However, its pathogenic role or clinical significance is not fully understood. The objective of this study was to examine the expression levels of adipophilin and related hypoxic signaling proteins and to determine their prognostic impacts and associations with the pathologic characteristics of lung adenocarcinoma.

METHODS

Expression levels of adipophilin, heat shock protein 27 (HSP27), carbonic anhydrase IX, and hypoxia-inducible factor 1α were examined by immunohistochemical staining using tissue microarray blocks. Correlations between protein expression levels and various clinicopathologic features were analyzed.

RESULTS

A total of 230 cases of primary adenocarcinoma of the lung were enrolled in this study. Adipophilin expression was more frequent in males and with the solid histologic type. It was correlated with HSP27 expression. Patients with adipophilin-positive adenocarcinoma showed a shorter progression-free survival (PFS) (median PFS, 17.2 months vs 18.4 months) in a univariable survival analysis, whereas HSP27 positivity correlated with favorable overall survival (OS) and PFS. In a multivariable analysis, adipophilin and HSP27 were independent prognostic markers of both OS and PFS.

CONCLUSIONS

Activated lipid metabolism and the hypoxic signaling pathway might play a major role in the progression of lung adenocarcinoma, especially in the solid histologic type.

Overexpression of PLIN2 is a prognostic marker and attenuates tumor progression in clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is the most common renal malignancy in adults, the incidence of which continues to increase. The lipid droplet protein perilipin 2 (PLIN2), which was originally considered an RNA transcript, is markedly expressed during adipocyte differentiation. In addition, it has been observed to be elevated in numerous types of cancer, including ccRCC; however, its essential function remains unclear in ccRCC. The present study examined the expression of PLIN2 in ccRCC, and aimed to determine the association between PLIN2 expression and patient survival. The present study mined the transcriptional, clinicopathological and survival data of PLIN2 in patients with ccRCC through The Cancer Genome Atlas. The expression levels of PLIN2 were also detected in human ccRCC tissues and cell lines by western blotting and immunohistochemistry, and its biological role was identified by functional analysis. The results demonstrated that PLIN2 was predominantly elevated in RCC tissues and cells. In addition, the expression levels of PLIN2 were significantly associated with various clinicopathological factors, and high PLIN2 expression was associated with a good prognosis. The results of a multivariate analysis demonstrated that high PLIN2 expression was an independent prognostic indicator of overall survival (hazard ratio, 0.586; P=0.001). Furthermore, PLIN2 knockdown promoted proliferation of ccRCC cells, and enhanced cell invasion and migration. These results suggested that PLIN2 may be considered a novel prognostic factor in ccRCC and a specific diagnostic indicator for patients with ccRCC. Furthermore, it could be a potential novel target for the clinical treatment of ccRCC.