An emerging role for the nuclear localization of maspin in the suppression of tumor progression and metastasis

Prognostic value of Maspin protein level in patients with triple negative breast cancer

The search for prognostic markers in breast cancer has bumped into a typical feature of these tumors, intra and intertumoral heterogeneity. Changes in the expression profile, localization of these proteins or shedding to the surrounding stroma can be useful in the search for new markers. In this context, classification by molecular subtypes can bring perspectives for both diagnosis and screening for appropriate treatments. However, the Triple Negative (TN) subtype, which is already the one with the worst prognosis, lacks appropriate and consistent molecular markers. In this work, we analyzed 346 human breast cancer samples in tissue microarrays (TMA) from cases diagnosed with invasive breast carcinoma to assess the expression and localization pattern of Maspin and their correlation with clinical parameters. To complement our findings, we also used TCGA data to analyze the mRNA levels of these respective genes. Our data suggests that the TN subtype demonstrates a higher level of cytoplasmic Maspin compared to the other subtypes. Maspin transcript levels follow the same trend. However, TN patients with lower Maspin expression tend to have worse overall survival and free-survival metastasis rates. Finally, we used Maspin expression data to verify possible relationships with the clinicopathological information of our cohort. Our univariate analyses indicate that Maspin is related to the expression of estrogen receptor (ER) and progesterone receptor (PR). Furthermore, Maspin expression levels also showed correlation with Scarff-Bloom-Richardson (SBR) parameter, and stromal Maspin showed a relationship with lymph node involvement. Our data is not consistently robust enough to categorize Maspin as a prognostic marker. However, it does indicate a change in the expression profile within the TN subtype.

miR-1204 Positioning in 8q24.21 Involved in the Tumorigenesis of Colorectal Cancer by Targeting MASPIN

BACKGROUND

Colorectal cancer remains to be the third leading cause of cancer mortality rates. Despite the diverse effects of the miRNA cluster located in PVT1 of 8q24.21 across various tumors, the specific biological function in colorectal cancer has not been clarified.

METHODS

The amplification of the miR-1204 cluster was analyzed with the cBioPortal database, while the expression and survival analysis of the miRNAs in the cluster were obtained from several GEO databases of colorectal cancer. To investigate the functional role of miR-1204 in colorectal cancer, overexpression and silencing experiments were performed by miR-1204 mimic and inhibitor transfection in colorectal cancer cell lines, respectively. Then, the effects of miR-1204 on cell proliferation were assessed through CCK-8, colony formation, and Edu assay. In addition, cell migration was evaluated using wound healing and Transwell assay. Moreover, candidate genes identified through RNA sequencing and predicted databases were identified and validated using PCR and western blot. A Dual-luciferase reporter experiment was conducted to identify MASPIN as the target gene of miR-1204.

RESULTS

In colorectal cancer, the miR-1204 cluster exhibited high amplification, and the expression levels of several cluster miRNAs were also significantly increased. Furthermore, miR-1204 was found to be significantly associated with disease-specific survival according to the analysis of GSE17536. Functional experiments demonstrated that transfection of miR-1204 mimic or inhibitor could enhance or decrease cancer cell proliferation and migration. MASPIN was identified as a target of miR-1204. Additionally, the overexpression of MASPIN partially rescued the effect of miR-1204 mimics on tumorigenic abilities in LOVO cells.

CONCLUSION

miR-1204 positioning in 8q24.21 promotes the proliferation and migration of colorectal cancer cells by targeting MASPIN.

Guardian of genome on the tract: Wild type p53-mdm2 complex inhibition in healing the breast cancer

Breast cancer acts as an assassin among women. According to WHO (world health organisation), about 6, 27,000 deaths have occurred in 2018 due to breast cancer. Since, the evolution of cancer involves many complicated pathway, in this article we have decided to focus on wild type p53. P53 is also called as tumor suppressor gene. As the name suggest, p53 is a real guardian of genome, if it is not mutated or subjected to degradation. It can perform a wide range of activities during cancer progression. It either stimulates or inhibits the genes or proteins that are responsible for cell cycle arrest, apoptosis, anti-angiogenic activity and anti-metastatic activity. At times, the p53 will be unable to produce its action due to various reasons like mutation or degradation by other proteins or degrading ligases. Since, we are focusing on wild type p53, it will be inhibited occasionally by mdm2 resulting in proteosomal degradation of p53. However, this condition can be prevented by possible treatment regimen. With the above points in mind, we have focused on p53 activation, complex formation between p53 and mdm2, and inhibition of the complex in order to free p53 and allow them to perform their action for rehabilitation of cancer. Furthermore, we have also discussed pathways involved in eradicating cancer through p53 activation. By considering the following aspects, hope that p53 can be considered for management of breast cancer.

Role of class I histone deacetylases in the regulation of maspin expression in prostate cancer

Maspin repression is frequently observed in prostate cancer; however, the molecular mechanism(s) causing the loss is not completely understood. Here, we demonstrate that inhibition of class I histone deacetylases (HDACs) mediates re-expression of maspin which plays an essential role in suppressing proliferation and migration capability in prostate cancer cells. Human prostate cancer LNCaP and DU145 cells treated with HDAC inhibitors, sodium butyrate, and trichostatin A, resulted in maspin re-expression. Interestingly, an exploration into the molecular mechanisms demonstrates that maspin repression in prostate tumor and human prostate cancer cell lines occurs via epigenetic silencing through an increase in HDAC activity/expression, independent of promoter DNA hypermethylation. Furthermore, transcriptional activation of maspin was accompanied with the suppression of HDAC1 and HDAC8 with significant p53 enrichment at the maspin promoter associated with an increase in histone H3/H4 acetylation. Our results provide evidence of maspin induction as a critical epigenetic event altered by class I HDACs in the restoration of balance to delay proliferation and migration ability of prostate cancer cells.

Vascular endothelial growth factor C participates in regulation of maspin in extravillous trophoblast cell migration and invasion

Mammary serine protease inhibitor (maspin ; also known as serpin family B member 5 (SERPINB5)) plays a vital role in regulating the biological functions of extravillous trophoblast (EVT) cells, but the mechanism remains unclear. Vascular endothelial growth factor (VEGF ) C is a signature angiogenic molecule expressed and secreted by first-trimester trophoblasts, and bioinformatics analyses has revealed upregulation of VEGFC in pre-eclampsia. The aim of this study was to explore whether maspin regulates EVT cells by regulating the expression of VEGFC . Reverse transcription-polymerase chain reaction and western blotting were used to investigate the effects of hypoxia on the expression of VEGFC in EVT cells. Cells were treated with recombinant (r) maspin and decitabine (to selectively inhibit DNA methyltransferases and then upregulate maspin gene expression), and the effects on VEGFC expression evaluated. In addition, the effects of rVEGFC on the biological functions of EVT cells invitro were evaluated using cell migration and invasion assays. Hypoxia increased the expression of VEGFC in EVT cells. rMaspin upregulated the expression of VEGFC in normoxic EVT cells, and downregulated the expression of VEGFC in hypoxic EVT cells at 24h. Decitabine increased VEGFC expression in normoxic EVT cells, but had no significant effect on VEGFC expression in hypoxic EVT cells. rVEGFC promoted the migration and invasion of normoxic EVT cells and inhibited the invasion of hypoxic EVT cells. These results suggest that VEGFC is involved in the regulation of maspin in EVT cell migration and invasion. However, other molecular mechanisms may be involved and require further investigation.

Identification of a putative nuclear localization signal in the tumor suppressor maspin sheds light on its nuclear import regulation

The tumor suppressor activity of maspin (mammary serine protease inhibitor) has been associated with its nuclear localization. In this study we explore the regulation of maspin nuclear translocation. An in vitro nuclear import assay suggested that maspin can passively enter the nucleus. However, in silico analysis identified a putative maspin nuclear localization signal (NLS), which was able to mediate the nuclear translocation of a chimeric protein containing this NLS fused to five green fluorescent protein molecules in tandem (5GFP). Dominant‐negative Ran‐GTPase mutants RanQ69L or RanT24N suppressed this process. Unexpectedly, the full‐length maspin fused to 5GFP failed to enter the nucleus. As maspin's putative NLS is partially hidden in its three‐dimensional structure, we suggest that maspin nuclear transport could be conformationally regulated. Our results suggest that maspin nuclear translocation involves both passive and active mechanisms.

Nuclear expression of onco-suppressors nm23-H1 and maspin are associated with lower recurrence rate in laryngeal carcinoma

PURPOSE

The main aim of the study was to preliminarily investigate the possibly related role of nuclear onco-suppressors maspin and nm23-H1, a metastasis suppressor, in laryngeal squamous cell carcinoma (LSCC).

MATERIALS AND METHODS

Maspin expression pattern and nuclear nm23-H1 expression were ascertained in 62 consecutive LSCCs.

RESULTS

Recurrence rate was significantly lower in patients with a nuclear maspin pattern of expression; nuclear nm23-H1 expression was significantly lower in patients who experienced disease recurrence. Disease free survival (DFS) was significantly longer in patients with maspin nuclear pattern or with nuclear nm23-H1 expression ≥10%. A significant association was found between nuclear nm23-H1 expression and maspin pattern of expression in LSCC. KNN discriminant analysis considered N status, maspin sub-cellular localization and nuclear nm23-H1 expression. The selected variables' accuracy in terms of relapse was 82%. Positive predictive accuracy was 100%, and negative predictive accuracy 79%.

CONCLUSIONS

Nuclear nm23-H1 expression and maspin pattern, also in association, show promise as recurrence indicators in LSCC. Further studies are needed to shed more light on the nm23-H1 mechanism of action in LSCC and thus find ways to restore nm23-H1 loss. These preliminary findings suggest that re-activating maspin functions might represent an important goal in the treatment of advanced LSCC.

Potential of Protein-based Anti-metastatic Therapy with Serpins and Inter α-Trypsin Inhibitors

In this review we summarize the principles of anti-metastatic therapy with selected serpin family proteins, such as pigment epithelial-derived factor (PEDF) and maspin, as well as inter α-trypsin inhibitor (IαIs) light chains (bikunin) and heavy chains (ITIHs). Case-by-case, antimetastatic activity may be dependent or independent of the protease-inhibitory activity of the corresponding proteins. We discuss the incidence of target deregulation in different tumor entities, mechanisms of deregulation, context-dependent functional issues as well as in vitro and in vivo target validation studies with transfected tumor cells or recombinant protein as anti-metastatic agents. Finally, we comment on possible clinical evaluation of these proteins in adjuvant therapy.

SERPINB5 Expression: Association with CCRT Response and Prognostic Value in Rectal Cancer

Background: Due to the varying characteristics and conflicting outcomes on the overall survival of rectal cancer patients, many studies have been undertaken to determine various prognostic and predictive factors for the mainstay treatment of CCRT followed by surgery. Cancer cell motility contributes to tumor invasion, migration and eventually metastasis. However, the genes associated with cell motility (i.e., GO:0048870) have not been systemically evaluated in rectal cancers. Methods: A comparative analysis of gene expression profiles was applied to the transcriptomic dataset (GSE35452) with a focus on genes associated with cell motility (GO:0048870), where SERPINB5 was recognized as the most significantly up-regulated gene. Tumor samples from 172 primary rectal cancer patients who underwent neoadjuvant CCRT followed by surgical resection were collected. Immunohistochemistry was used to semi-quantitatively assess the expression level of SERPINB5 protein. Statistical analyses of SERPINB5 expression and various clinicopathological features as well as survival were then performed. Results: High immunoreactivity of SERPINB5 was significantly linked to pre- and post-CCRT advanced disease, lymphovascular invasion, and poor response to CCRT (all P ≤ 0.015). SERPINB5 overexpression was not only negatively associated with disease-specific survival (DSS), local recurrence-free survival (LRFS) and metastasis-free survival (MeFS) rates in univariate analyses but also was an independent prognostic factor for DSS and MeFS in rectal cancer patients (all P ≤ 0.043). Conclusion: SERPINB5 may play an important role in rectal cancer progression and response to neoadjuvant CCRT and serve as a novel prognostic factor.

Expression levels and clinical significance of hepsin and HMGB1 proteins in cervical carcinoma

This study assessed the hypothesis that the protein levels of high mobility group box 1 (HMGB1) and hepsin can be used as markers for diagnosis and prognosis in cervical carcinoma. Seventy patients with cervical cancer who were hospitalized in Xuzhou Central Hospital from May 2008 to June 2010 and underwent surgical treatment were selected for the observation group. At the same time, 20 patients with cervical benign lesions who underwent tumor stripping or accessory resection were selected for the control group. Immunohistochemical (SP) detection methods were used to detect hepsin and HMGB1 protein levels in tissues. The positive rates of HMGB1 cells in normal, paracancerous and cancerous cervical tissues were 5.0% (1/20), 22.9% (16/70) and 95.7% (67/70) (F=24.581, P=0.001) respectively. The positive rates of hepsin in normal, paracancerous and cancerous cervical tissues were respectively 10% (2/20), 61% (43/70) and 90% (63/70) (F=11.538, P=0.001). The HMGB1 expression level was related to the degree of tumor differentiation, lymph node metastasis and TNM stage (P<0.05). While the level of hepsin expression was related to the degree of tumor differentiation, invasion depth, lymph node metastasis and TNM stage (P<0.05). Furthermore, a positive correlation between the levels of hepsin and HMGB1 was found (r=15.27, P<0.05). The overall 5-year survival rates of patients with high expression of HMGB1 (+++) and low expression of HMGB1 (+ to ++) were respectively 51.2 and 29.2% (HR=11.637, 95% CI=4.351-38.213; P=0.002). The overall 5-year survival rates of patients with high hepsin expression (+++) and low hepsin expression (+ to ++) were respectively 41.3 and 35.3% (HR=10.143, 95% CI=4.285-33.275; P=0.006). Based on our results, the higher the levels of expression of hepsin and HMGB1 in tissues the higher the degree of invasiveness of the cervical cancers, and the worse the prognoses for the patient.

The Opportunity of Precision Medicine for Breast Cancer With Context-Sensitive Tumor Suppressor Maspin

To improve the precision of molecular diagnosis and to develop and guide targeted therapies of breast cancer, it is essential to determine the mechanisms that underlie the specific tumor phenotypes. To this end, the application of a snapshot of gene expression profile for breast cancer diagnosis and prognosis is fundamentally challenged since the tissue-based data are derived from heterogonous cell types and are not likely to reflect the dynamics of context-dependent tumor progression and drug sensitivity. The intricate network of epithelial differentiation program can be concertedly controlled by tumor suppressor maspin, a homologue of clade B serine protease inhibitors (serpin), through its multifaceted molecular interactions in multiple subcellular localizations. Unlike most other serpins that are expressed in multiple cell types, maspin is epithelial specific and has distinct roles in luminal and myoepithelial cells. Endogenously expressed maspin has been found in the nucleus and cytoplasm, and detected on the surface of cell membrane. It is also secreted free and as an exosomal cargo protein. Research in the field has led to the identification of the maspin targets and maspin-associated molecules, as well as the structural determinants of its suppressive functions. The current review discusses the possibility for maspin to serve as a cell type-specific and context-sensitive marker to improve the precision of breast cancer diagnosis and prognosis. These advancements further suggest a new window of opportunity for designing novel maspin-based chemotherapeutic agents with improved anti-cancer potency. J. Cell. Biochem. 118: 1639-1647, 2017. © 2017 Wiley Periodicals, Inc.

Dormant Cells: The Original Cause of Tumor Recurrence and Metastasis

Tumor dormancy is one of the stages in tumor development without clinical symptoms. Tumor dormant cells may appear in early stages of tumor development, as well as in micrometastasis and minimal residual disease. The mechanism for the switch of dormant cells between quiescent and proliferative stages is still largely unknown. Potential mechanisms that may account for the transition between dormant tumor cells and proliferative cells include angiogenesis, immune response, cellular factors, and signaling pathways. The clinical and therapeutic importance of dormant cells requires further studies to provide therapeutic strategies for inhibition of metastasis and tumor recurrence.

Carboxyl-terminal truncated HBx contributes to invasion and metastasis via deregulating metastasis suppressors in hepatocellular carcinoma

Hepatitis B virus (HBV) X protein (HBx), a trans-regulator, is frequently expressed in truncated form without carboxyl-terminus in hepatocellular carcinoma (HCC), but its functional mechanisms are not fully defined. In this report, we investigated frequency of this natural HBx mutant in HCCs and its functional significance. In 102 HBV-infected patients with HCC, C-terminal truncation of HBx, in contrast to full-length HBx, were more prevalent in tumors (70.6%) rather than adjacent non-tumorous tissues (29.4%) (p = 0.0032). Furthermore, two naturally-occurring HBx variants (HBxΔ31), which have 31 amino acids (aa) deleted (codons 123-125/124-126) at C-terminus were identified in tumors and found that the presence of HBxΔ31 significantly correlated with intrahepatic metastasis. We also show that over-expression of HBxΔ31 enhanced hepatoma cell invasion in vitro and metastasis in vivo compared to full-length HBx. Interestingly, HBxΔ31 exerts this function via down-regulating Maspin, RhoGDIα and CAPZB, a set of putative metastasis-suppressors in HCC, in part, by enhancing the binding of transcriptional repressor, myc-associated zinc finger protein (MAZ) to the promoters through physical association with MAZ. Notably, these HBxΔ31-repressed proteins were also significantly lower expression in a subset of HCC tissues with C-terminal HBx truncation than the adjacent non-tumorous tissues, highlighting the clinical significance of this novel HBxΔ31-driven metastatic molecular cascade. Our data suggest that C-terminal truncation of HBx, particularly breakpoints at 124aa, plays a role in enhancing hepatoma cell invasion and metastasis by deregulating a set of metastasis-suppressors partially through MAZ, thus uncovering a novel mechanism for the progression of HBV-associated hepatocarcinogenesis.

Maspin-related Orchestration of Aggressiveness of Gastric Cancer

BACKGROUND AND STUDY AIM

Although some hypotheses have been postulated on the genesis of gastric cancer (GC), the origin of this disease remains unclear. The aim of this study was to develop a hypothesis about gastric carcinogenesis based on our experience in the field of GC and on published reports on about 28 studies in the field of subcellular maspin expression in GC. In 180 cases of GC, the clinicopathologic features were correlated with the results obtained after paired immunohistochemical stains (tumor/normal mucosa) with 15 antibodies: E-cadherin, HER-2, VEGF, CD31, CD105, COX-2, maspin, bax, bcl-2, p53, Ki67, MLH-1, MSH-2, Mena protein, and vimentin.

RESULTS

Cytoplasmic maspin was observed in foveolar cells with intestinal metaplasia, whereas mixed (combined nuclear-cytoplasmic) expressions were more characteristic of the intramucosal foci of signet-ring cells and dysplastic cells. The tumor cells that expressed cytoplasmic maspin were mostly intestinal type bax/COX-2/Mena/E-cadherin-positive differentiated adenocarcinomas with nodular growth and more superficial invasion. The nuclear shift of maspin was more frequent in HER-2/p53-positive intestinal type adenocarcinomas with diffuse architecture at the invasion front, as well as for node-positive poorly cohesive carcinomas. Loss of maspin expression induced a higher risk of distant metastases, without differences in the survival rate.

CONCLUSIONS

In GC with associated metaplasia, cytoplasmic maspin is predominant; the nuclear shift induces local aggressiveness and risk of node metastases, whereas total loss can indicate a risk of distant metastases. In GC without associated metaplasia, nuclear expression of maspin is retained, indicating a more aggressive behavior.

Cytoplasmic expression of maspin predicts unfavourable prognosis in patients with squamous cell carcinoma of the lung

AIMS

Maspin is known to be a tumour suppressor protein, and its prognostic significance in patients with several types of cancer, including lung squamous cell carcinoma (SCC), has been reported. However, its prognostic impact on lung SCC has been controversial. We explored the prognostic value of maspin expression with particular reference to its subcellular localization in patients with lung SCC.

METHODS AND RESULTS

Paraffin-embedded tissue samples from 101 curatively resected patients with lung SCC were analysed immunohistochemically using an antibody for maspin. Maspin positivity was defined as strong expression in only the cytoplasm and observed in 25 patients (24.6%). It correlated significantly with the presence of lymph node metastasis (P = 0.006) and higher pathological stage (P = 0.003). The patients were followed-up for 2-119 months (median: 50 months), and the maspin-positive group had shorter disease-free survival (DFS) and disease-specific survival (DSS) by log-rank test (P = 0.002, P = 0.016, respectively). Multivariate analysis revealed that the status of maspin was the only independent prognostic factor for DFS and DSS (P = 0.017, P = 0.047, respectively).

CONCLUSIONS

Cytoplasmic expression of maspin could be an independent unfavourable prognostic indicator in patients with lung SCC.

The role of serpins in tumor cell migration

Tumor cells are characterized by uncontrolled cell growth at a primary site that is caused by genetic alterations. Tumor cells that metastasize from their primary site to distant locations are commonly referred to as malignant. Cell migration is a critical step in this process. The ability of tumor cells to migrate and invade is partly controlled by proteolytic enzymes. These enzymes are secreted by either the tumor cells themselves or adjacent cells. They represent all classes of proteases, including serine and cysteine proteases. Serine proteases, in particular urokinase plasminogen activator (uPA), initiate a proteolytic cascade that culminates in degrading components of the extracellular matrix (ECM). Some serine proteases are controlled by a superfamily of proteins known as serpins. This minireview provides an overview of serpins that are vital in regulating tumor cell migration and progressing cancer.

Diagnostic value of maspin in distinguishing adenocarcinoma from benign biliary epithelium on endoscopic bile duct biopsy

Histopathologic distinction between benign and malignant epithelia on endoscopic bile duct biopsy can be extremely challenging due to small sample size, crush artifact, and a propensity for marked inflammatory and reactive changes after stent placement. Our previous studies have shown that the insulin-like growth factor II mRNA-binding protein 3, S100P, and the von Hippel-Lindau gene product (pVHL) can help the distinction. This study analyzed 134 endoscopic bile duct biopsy specimens (adenocarcinoma 45, atypical 31, and benign 58) by immunohistochemistry for the expression of maspin, a serine protease inhibitor. The results demonstrated that (1) maspin expression was more frequently detected in malignant than in benign biopsies; (2) malignant biopsies frequently showed diffuse, strong/intermediate, and combined nuclear/cytoplasmic staining patterns for maspin, which were much less commonly seen in benign biopsies; (3) the malignant staining patterns for maspin observed in atypical biopsies were consistent with follow-up data showing that 67% of these patients were subsequently diagnosed with adenocarcinoma; (4) a maspin+/S100P+/pVHL- staining profile was seen in 75% of malignant biopsies but in none of the benign cases. These observations demonstrate that maspin is a useful addition to the diagnostic immunohistochemical panel (S100P, pVHL, and insulin-like growth factor II mRNA-binding protein 3) to help distinguish malignant from benign epithelia on challenging bile duct biopsies.

Nuclear maspin expression as a predictive marker for fluorouracil treatment response in colon cancer

BACKGROUND

Maspin is a member of the serpin family of protease inhibitors whose function in colorectal cancer is not fully understood. The objective of this study was to determine whether level of maspin expression could have prognostic or predictive value in colorectal cancer.

MATERIAL AND METHODS

Maspin expression was assessed using immunohistochemistry on tissue microarrays obtained from 380 patients with stage II and III colorectal cancer randomized to adjuvant chemotherapy with fluorouracil and levamisole (5-FU/Lev) or to surgery only (control), with scores (0-300) based on presence (0-100) and intensity (0-3) of maspin expression. Associations with disease-free survival (DFS), cancer-specific survival (CSS) and prognostic factors were determined.

RESULTS

Maspin expression was predominantly nuclear and present in tumor tissue in 99% of the cases. No associations with clinicopathological factors were identified. In colon cancer patients receiving adjuvant chemotherapy, maspin expression level was significantly associated with CSS [HR 1.43 per 50 points increase in maspin score (p = 0.021)] in multivariate analyses, and a significant interaction between treatment status and maspin expression (p = 0.045) was found. Kaplan-Meier plots from colon cancer patients showed a significant treatment benefit in patients with low maspin expression, but not for individuals with medium/high expression. Level of maspin expression was not significantly related to clinical outcome in rectal cancer or in any of the control groups.

CONCLUSIONS

In patients with colon cancer a low nuclear maspin expression was an independent predictor of benefit from adjuvant chemotherapy with 5-FU/Lev. A prognostic value of maspin expression was not found in this material.

Expression and localization of maspin in cervical cancer and its role in tumor progression and lymphangiogenesis

Objectives

Cervical cancer is the most common malignant tumor in female reproductive tract and primarily metastasizes through the lymphatic system that will affect prognosis of patients. Maspin, a member of the serine protease inhibitors (serpins) super family, has recently been indicated as a tumor suppressor in many cancers. In this study, we investigated the clinical significance of maspin expression, especially the subcellular location of maspin and its functional role in progression and lymphangiogenesis, in cervical squamous cell carcinoma.

Methods

Labelled streptavidin biotin method (LSAB) was used to determine cytoplasmic and nuclear maspin expressions, respectively, in 13 cases of normal cervix, 15 cases of cervical intraepithelial neoplasia grade 3 (CIN3), 62 cases of squamous cell carcinoma (SCC) of the uterine cervix, and 13 cases of pelvic lymphatic nodes which were all positive lymphatic nodes in our selected cancer cases. LSAB is also used to detect podoplanin which is used for counting density of lymphatic microvessels (LMVD). The clinical significance of subcellular maspin expression and the relationship between maspin expression and LMVD in cervical cancer are analyzed.

Results

Both cytoplasmic and nuclear maspin expressions in SCC were significantly weaker than those of normal cervix and CIN3. Nuclear maspin expression showed a peak in CIN3 and then dropped in SCC. Declined maspin expression was correlated with later clinical stage, increased LMVD, and lymphatic metastasis.

Conclusions

Our results suggest that subcellular location of maspin expression is a potential predictive factor in tumor progression and in patients’ prognosis of cervical cancer, and maspin plays a suppression role in lymphangiogenesis and metastasis.

TUBB3/βIII-tubulin acts through the PTEN/AKT signaling axis to promote tumorigenesis and anoikis resistance in non-small cell lung cancer

βIII-tubulin (encoded by TUBB3) expression is associated with therapeutic resistance and aggressive disease in non-small cell lung cancer (NSCLC), but the basis for its pathogenic influence is not understood. Functional and differential proteomics revealed that βIII-tubulin regulates expression of proteins associated with malignant growth and metastases. In particular, the adhesion-associated tumor suppressor maspin was differentially regulated by βIII-tubulin. Functionally, βIII-tubulin suppression altered cell morphology, reduced tumor spheroid outgrowth, and increased sensitivity to anoikis. Mechanistically, the PTEN/AKT signaling axis was defined as a critical pathway regulated by βIII-tubulin in NSCLC cells. βIII-Tubulin blockage in vivo reduced tumor incidence and growth. Overall, our findings revealed how βIII-tubulin influences tumor growth in NSCLC, defining new biologic functions and mechanism of action of βIII-tubulin in tumorigenesis.

Internalization by multiple endocytic pathways and lysosomal processing impact maspin-based therapeutics

Patients with metastatic disease face high rates of mortality with a paucity of therapeutic options. Protein-based therapeutics provide advantages over traditional chemotherapy through increased specificity, decreased immune impairment, and more direct means of delivery. However, development is often hindered because of insufficient knowledge about protein processing by cells when exogenously applied. This study focuses on recombinant Maspin (rMaspin), a serine protease inhibitor (SERPINB5), which alters invasive properties when directly applied to cancer cells. Previous evidence suggests differences in the effects of rMaspin treatment when compared with endogenous reexpression, with little explanation for these discrepancies. A leading hypothesis is that exogenously applied rMaspin is subject to different regulatory and/or processing mechanisms in cancer cells when compared with endogenous expression. Therefore, a more detailed understanding of the mechanisms of internalization and subcellular trafficking of rMaspin is needed to guide future translational development. We describe the molecular trafficking of rMaspin in cytoplasmic vesicles of the endosomal/lysosomal pathway and characterize its uptake by multiple endocytic mechanisms. Time-lapse laser scanning confocal microscopy shows the uptake, in real time, of dye-labeled rMaspin in cancer cells. This study indicates that cellular processing of rMaspin plays a key role by affecting its biologic activity and highlights the need for new approaches aimed at increasing the availability of rMaspin when used to treat cancer.

IMPLICATIONS

Novel characterization of internalization and subcellular trafficking of rMaspin provides new insights for future therapeutic development.

Maspin expression patterns differ in the invasive versus lepidic growth pattern of pulmonary adenocarcinoma

Aims

To test whether changes in the subcellular localization of maspin parallel morphological progression in pulmonary adenocarcinoma, we compared its expression between lepidic and invasive growth patterns.

Methods

Applying immunohistochemistry, we compared maspin expression in lepidic and invasive growth patterns occurring in different tumours (series #1, n = 86) as well as within the same tumour and in the same section (series #2, n = 29).

Results

In both series, the lepidic growth pattern (n = 45) was significantly associated with nuclear maspin, while the invasive (n = 70) with combined nuclear and cytoplasmic maspin (P < 0.05). In the second series, transition from a lepidic to an invasive pattern in the same tumour was associated predominantly with a shift respectively from a nuclear to a combined nuclear and cytoplasmic maspin (15/29) or preservation of nuclear expression (8/29). A shift from nuclear maspin to negative expression (3/29) or other patterns (3/29) were also observed.

Conclusions

Nuclear maspin is a typical but not exclusive feature of the lepidic growth pattern of pulmonary adenocarcinoma, whereas combined nuclear and cytoplasmic maspin characterizes invasion. These data show that changes of expression and subcellular localization of maspin may constitute an important biological end point of tumour progression and aid in the classification of lung adenocarcinoma.

Expression of CD34 and maspin in ameloblastoma from a West African subpopulation

Ameloblastoma is a locally invasive odontogenic tumor with a high recurrence rate. Its local invasiveness is aided by angiogenesis, which can be correctly estimated by CD34. On the other hand, maspin decreases the local invasive and metastatic capability of cancer cells and functions as an angiogenesis inhibitor. We aim to assess the association between maspin expression and microvessel density in ameloblastoma. Twenty-five formalin-fixed paraffin-embedded (FFPE) blocks of ameloblastoma cases were prepared for antibody processing to CD34 and maspin. Positive immunohistochemical staining was marked by brown cytoplasmic/membrane coloration for CD34 and by nuclear/cytoplasmic coloration for maspin. At the ×40 magnification, we counted blood vessels in two areas of dimension; 300 × 400 μm (area A) and 150 × 200 μm (area B) adjacent to the tumor region to assess relative dispersion of the vessels bordering the tumor. The overall approximate microvessel density (MVD) for area A = 11 (minimum 2, maximum 21) and that for area B = 5 (minimum 1, maximum 10). The MVD in the area A of plexiform ameloblastoma was similar to that of the unicystic, while the hemangiomatous variant had the highest MVD for area A. Maspin positivity was present only in the cytoplasm of ameloblast, stellate reticulum, and the fibrous connective tissue in varying proportions. There was no evidence of the anti-angiogenesis effect of maspin in ameloblastoma from this study. The significance of cytoplasmic localization of maspin in the ameloblasts and stellate reticulum cells needs further investigation.

Maspin expression and melanoma progression: a matter of sub-cellular localization

Maspin, a member of the serpin family of protease inhibitors, is involved in key processes of cancer progression. Its biological activity seems to be cancer and compartment specific, with the protein acting either as a suppressor or as a tumor promoter in different cancer types. Characterization of maspin expression and its sub-cellular localization in melanoma is missing, hence, we aim to investigate its possible association with melanoma prognostic factors and disease progression. Nuclear and cytoplasmic maspin expression were evaluated on 60 nevi, 152 primary lesions, and 106 melanoma metastases using tissue microarrays and immunohistochemistry. The association between maspin immunoreactivity and patient's clinic-pathological features was evaluated. Multivariate logistic models and survival analyses were performed for maspin expression in primary melanomas. Nuclear maspin was detected in 8% nevi, 49% primary melanomas, and 28% metastases, whereas cytoplasmic maspin in 12% nevi, 18% primary lesions, and 9% metastases. In univariate analysis, nuclear maspin expression in primary melanomas was significantly associated with melanoma prognostic factors (nodular histotype, tumor thickness, mitotic rate, and ulceration) and disease stage, whereas cytoplasmic maspin was observed at higher frequency in thin superficial spreading melanomas, without mitosis. In multivariate analysis, nuclear maspin remained significantly associated with risk of developing a tumor prone to disease progression and, accordingly, with significantly shorter disease-free and overall survival. In this study, maspin was expressed at highest frequency in primary lesions and when expressed in the nuclei, was significantly associated with poor prognostic markers, melanoma recurrence, and worse survival. The present study suggests a tumor-suppressive effect of cytoplasmic maspin and a tumor-promoting effect of nuclear maspin, which open the discussion on its potential use in cancer therapy.

Identification of an intrinsic determinant critical for maspin subcellular localization and function

Maspin, a multifaceted tumor suppressor, belongs to the serine protease inhibitor superfamily, but only inhibits serine protease-like enzymes such as histone deacetylase 1 (HDAC1). Maspin is specifically expressed in epithelial cells and it is differentially regulated during tumor progression. A new emerging consensus suggests that a shift in maspin subcellular localization from the nucleus to the cytoplasm stratifies with poor cancer prognosis. In the current study, we employed a rational mutagenesis approach and showed that maspin reactive center loop (RCL) and its neighboring sequence are critical for maspin stability. Further, when expressed in multiple tumor cell lines, single point mutation of Aspartate(346) (D(346)) to Glutamate (E(346)), maspin(D346E), was predominantly nuclear, whereas wild type maspin (maspin(WT)) was both cytoplasmic and nuclear. Evidence from cellular fractionation followed by immunological and proteomic protein identification, combined with the evidence from fluorescent imaging of endogenous proteins, fluorescent protein fusion constructs, as well as bimolecular fluorescence complementation (BiFC) showed that the increased nuclear enrichment of maspin(D346E) was, at least in part, due to its increased affinity to HDAC1. Maspin(D346E) was also more potent than maspin(WT) as an HDAC inhibitor. Taken together, our evidence demonstrates that D(346) is a critical cis-element in maspin sequence that determines the molecular context and subcellular localization of maspin. A mechanistic model derived from our evidence suggests a new window of opportunity for the development of maspin-based biologically competent HDAC inhibitors for cancer treatment.

Serpin B5 is a CEA-interacting biomarker for colorectal cancer

Serpin B5 is a candidate tumour suppressor, but its oncogenic activity has also been reported. Its function may be affected by protein interactions. The aim of this study was to assess the relationship between serpin B5 and carcinoembryonic antigen (CEA) expression in colorectal cancer (CRC). We also analysed the clinicopathological significance of serpin B5 expression in patients with CRC. Downregulation of serpin B5 was identified in a CEA-suppressed LoVo cell line using two-dimensional gel electrophoresis (2-DE) and matrix-associated laser desorption ionisation-mass spectrometry (MALDI-MS). The specific interaction and co-localisation of serpin B5 with CEA were confirmed by co-immunoprecipitation and confocal microscopy. Western blot analysis and ELISAs revealed significant positive correlations between levels of serpin B5 and CEA in human colon cancer cell lines and in the blood of patients with CRC. Tissue expression of serpin B5 in 377 patients with CRC was significantly associated with serum CEA, histological grade, stage, lymph node metastasis, lymphatic and perineural invasion, and infiltrative border. Strong expression of serpin B5 was also associated with a reduced DFS (p = 0.001) and OS (p = 0.017). Together, these findings describe a relationship between serpin B5 and CEA expression in CRC. Strong expression of serpin B5 was associated with a worse prognosis in patients with CRC and its expression may correlate with CEA levels in CRC.

Maspin: molecular mechanisms and therapeutic implications

Maspin, a non-inhibitory member of the serine protease inhibitor superfamily, has been characterized as a tumor suppressor gene in multiple cancer types. Among the established anti-tumor effects of Maspin are the inhibition of cancer cell invasion, attachment to extracellular matrices, increased sensitivity to apoptosis, and inhibition of angiogenesis. However, while significant experimental data support the role of Maspin as a tumor suppressor, clinical data regarding the prognostic implications of Maspin expression have led to conflicting results. This highlights the need for a better understanding of the context dependencies of Maspin in normal biology and how these are perturbed in the context of cancer. In this review, we outline the regulation and roles of Maspin in normal and developmental biology while discussing novel evidence and emerging theories related to its functions in cancer. We provide insight into the immense therapeutic potential of Maspin and the challenges related to its successful clinical translation.

A versatile monoclonal antibody specific to human SERPINB5

Maspin (SERPINB5) is a member of the Clade B subgroup of the large superfamily of serine protease inhibitors. It is proposed that maspin is a tumor suppressor; however, its molecular role remains to be elucidated. Here we report the characterization of a mouse monoclonal antibody directed against human maspin. This antibody, 16F7, recognizes maspin in both its native and denatured form, unlike several other commercial antibodies tested in this study. It will be a useful and versatile tool for future analyses of the biological function of maspin.

Role of maspin in cancer

Maspin (mammary serine protease inhibitor), is a member of the serine protease inhibitor/non-inhibitor superfamily. Its expression is down-regulated in breast, prostate, gastric and melanoma cancers but over-expressed in pancreatic, gallbladder, colorectal, and thyroid cancers suggesting that maspin may play different activities in different cell types. However, maspin expression seems to be correlated with better prognosis in prostate, bladder, lung, gastric, colorectal, head and neck, thyroid and melanoma cancer. In breast and ovarian cancer maspin significance is associated with its subcellular localization: nucleus maspin expression correlates with a good prognosis, whilst in pancreatic cancer it predicts a poor prognosis. Since tumor metastasis requires the detachment and invasion of tumor cells through the basement membrane and stroma, a selectively increased adhesion by the presence of maspin may contribute to the inhibition of tumor metastasis. Furthermore the different position of maspin inside the cell or its epigenetic modifications may explain the different behavior of the expression of maspin between tumors. The expression of maspin might be useful as a prognostic and possibly predictive factor for patients with particular types of cancer and data can guide physicians in selecting therapy. Its expression in circulating tumor cells especially in breast cancer, could be also useful in clinical practice along with other factors, such as age, comorbidities, blood examinations in order to select the best therapy to be carried out. Focusing on the malignancies in which maspin showed a positive prognostic value, therapeutic approaches studied so far aimed to re-activate a dormant tumor suppressor gene by designed transcription factors, to hit the system that inhibits the expression of maspin, to identify natural substances that can determine the activation and the expression of maspin or possible “molecules binds” to introduce maspin in cancer cell and gene therapy capable of up-regulating the maspin in an attempt to reduce primarily the risk of metastasis.

Further studies in these directions are necessary to better define the therapeutic implication of maspin.

Tyrosine phosphorylation plays a role in increasing maspin protein levels and its cytoplasmic accumulation

Maspin is a tumor suppressor with many biological activities, multiple ligands and different subcellular localizations. Its underlying molecular mechanism remains elusive. We hypothesized that phosphorylation might regulate maspin localization and function. Using two-dimensional gel electrophoresis with different focusing power followed by Western blot we identified four different maspin forms with the same molecular weight (42 kDa), but different isoelectric points. Three of these forms were sensitive to acidic phosphatase treatment, suggesting that they are phosphorylated. Sodium peroxidovanadate treatment, a protein-tyrosine phosphatase inhibitor, resulted in a rapid increase in maspin protein levels and cytoplasmic accumulation. These data show that there are three different maspin tyrosine phosphoforms. Inhibition of tyrosine phosphatases increased maspin protein levels and leads to its cytoplasmic accumulation.