Upregulation of hyaluronan binding protein 1 (HABP1/p32/gC1qR) is associated with Cisplatin induced apoptosis

Biomimetic Hyaluronan Binding Biomaterials to Capture the Complex Regulation of Hyaluronan in Tissue Development and Function

Within native ECM, Hyaluronan (HA) undergoes remarkable structural remodeling through its binding receptors and proteins called hyaladherins. Hyaladherins contain a group of tandem repeat sequences, such as LINK domains, BxB7 homologous sequences, or 20-50 amino acid long short peptide sequences that have high affinity towards side chains of HA. The HA binding sequences are critical players in HA distribution and regulation within tissues and potentially attractive therapeutic targets to regulate HA synthesis and organization. While HA is a versatile and successful biopolymer, most HA-based therapeutics have major differences from a native HA molecule, such as molecular weight discrepancies, crosslinking state, and remodeling with other HA binding proteins. Recent studies showed the promise of HA binding domains being used as therapeutic biomaterials for osteoarthritic, ocular, or cardiovascular therapeutic products. However, we propose that there is a significant potential for HA binding materials to reveal the physiological functions of HA in a more realistic setting. This review is focused on giving a comprehensive overview of the connections between HA's role in the body and the potential of HA binding material applications in therapeutics and regenerative medicine. We begin with an introduction to HA then discuss HA binding molecules and the process of HA binding. Finally, we discuss HA binding materials anf the future prospects of potential HA binding biomaterials systems in the field of biomaterials and tissue engineering.

gC1qR: A New Target for Cancer Immunotherapy

Although breakthroughs in cancer treatment have been achieved, immunotherapy yields only modest benefits in most patients. There is still a gap in clarifying the immune evasiveness and immune-resistance mechanisms. Identifying other candidate targets for cancer immunotherapy is therefore a clear unmet clinical need. The complement system, a pillar of innate immunity, has recently entered the limelight due to its immunoregulatory functions in the tumor microenvironment (TME). In particular, gC1qR, a receptor for globular heads of C1q, serves as a promising new target and has attracted more attention. gC1qR, also named P32/C1qBP/HABP1, is a multifunctional protein that is overexpressed in various cancers and holds prognostic value. It regulates the tumorigenic, progression and metastatic properties of tumor cells through several downstream signaling pathways, including the Wnt/β-catenin, PKC-NF-κB and Akt/PKB pathways. A few preclinical experiments conducted through gC1qR interventions, such as monoclonal antibody, chimeric antigen receptor T-cell (CAR-T) therapy, and tumor vaccination, have shown encouraging results in anticancer activity. The efficacy may rely on the regulatory role on the TME, induction of tumor cells apoptosis and antiangiogenic activity. Nevertheless, the current understanding of the relationship between cancer immunotherapy and gC1qR remains elusive and often contradictory, posing both opportunities and challenges for therapeutic translation in the clinic. In this review, we focus on the current understanding of gC1qR function in cancer immunology and highlight the vital roles in regulating the TME. We also examines the rationale behind targeting gC1qR and discusses the potential for translating into clinical practice.

An approach to p32/gC1qR/HABP1: a multifunctional protein with an essential role in cancer

P32/gC1qR/HABP1 is a doughnut-shaped acidic protein, highly conserved in eukaryote evolution and ubiquitous in the organism. Although its canonical subcellular localization is the mitochondria, p32 can also be found in the cytosol, nucleus, cytoplasmic membrane, and it can be secreted. Therefore, it is considered a multicompartmental protein. P32 can interact with many physiologically divergent ligands in each subcellular location and modulate their functions. The main ligands are C1q, hyaluronic acid, calreticulin, CD44, integrins, PKC, splicing factor ASF/SF2, and several microbial proteins. Among the functions in which p32 participates are mitochondrial metabolism and dynamics, apoptosis, splicing, immune response, inflammation, and modulates several cell signaling pathways. Notably, p32 is overexpressed in a significant number of epithelial tumors, where its expression level negatively correlates with patient survival. Several studies of gain and/or loss of function in cancer cells have demonstrated that p32 is a promoter of malignant hallmarks such as proliferation, cell survival, chemoresistance, angiogenesis, immunoregulation, migration, invasion, and metastasis. All of this strongly suggests that p32 is a potential diagnostic molecule and therapeutic target in cancer. Indeed, preclinical advances have been made in developing therapeutic strategies using p32 as a target. They include tumor homing peptides, monoclonal antibodies, an intracellular inhibitor, a p32 peptide vaccine, and p32 CAR T cells. These advances are promising and will allow soon to include p32 as part of targeted cancer therapies.

Globular C1q Receptor (gC1qR/p32/HABP1) Is Overexpressed in Malignant Pleural Mesothelioma and Is Associated With Increased Survival in Surgical Patients Treated With Chemotherapy

Introduction: Globular C1q receptor (gC1qR/p32/HABP1) is overexpressed in a variety of cancers, particularly adenocarcinomas. This study investigated gC1qR expression in malignant pleural mesothelioma (MPM) and its pathophysiologic correlates in a surgical patient cohort.

Methods: Tissue microarrays comprising 6 tumoral and 3 stromal cores from 265 patients with MPM (216 epithelioid, 26 biphasic, and 23 sarcomatoid; 1989–2010) were investigated by immunohistochemistry for gC1qR expression (intensity and distribution by H-score, range 0–300), and immune cell infiltration. Overall survival (OS) was analyzed by the Kaplan-Meier method (high vs. low gC1qR expression delineated by median score) in the whole cohort and by neoadjuvant chemotherapy (NAC) status. Multivariable Cox analysis included stage, chemotherapy, and immune cell infiltration.

Results: gC1qR was overexpressed in all histological types of MPMs (263/265, 99.2%) compared to normal pleura. In epithelioid MPM, high gC1qR expression was associated with better OS (median 25 vs. 11 months; p = 0.020) among NAC patients, and among patients without NAC (No-NAC) but who received post-operative chemotherapy (median OS 38 vs. 19 months; p = 0.0007). In multivariable analysis, high gC1qR expression was an independent factor for improved OS in patients treated with NAC. In the No-NAC cohort, high gC1qR expression correlated with lower tumor stage. Moreover, the influence of Ki67 and CD4 T-cell infiltration on OS were more pronounced among patients with high gC1qR expression.

Conclusion: This is the first description of gC1qR expression in MPM. The data identify gC1qR as a potential new prognostic factor in patients treated with surgery and chemotherapy.

C1QBP Promotes Homologous Recombination by Stabilizing MRE11 and Controlling the Assembly and Activation of MRE11/RAD50/NBS1 Complex

MRE11 nuclease forms a trimeric complex (MRN) with RAD50 and NBS1 and plays a central role in preventing genomic instability. When DNA double-strand breaks (DSBs) occur, MRN is quickly recruited to the damage site and initiates DNA end resection; accordingly, MRE11 must be tightly regulated to avoid inefficient repair or nonspecific resection. Here, we show that MRE11 and RAD50 form a complex (MRC) with C1QBP, which stabilizes MRE11/RAD50, while inhibiting MRE11 nuclease activity by preventing its binding to DNA or chromatin. Upon DNA damage, ATM phosphorylates MRE11-S676/S678 to quickly dissociate the MRC complex. Either excess or insufficient C1QBP impedes the recruitment of MRE11 to DSBs and impairs the DNA damage response. C1QBP is highly expressed in breast cancer and positively correlates with MRE11 expression, and the inhibition of C1QBP enhances tumor regression with chemotherapy. By influencing MRE11 at multiple levels, C1QBP is, thus, an important player in the DNA damage response.

High cytoplasm HABP1 expression as a predictor of poor survival and late tumor stage in pancreatic ductal adenocarcinoma patients

BACKGROUND

Hyaluronan-binding protein 1 (HABP1) overexpression has been confirmed in different malignancies and found to be strongly associated with tumor development and progression. The aim of the present study was to explore the impact of HABP1 in pancreatic ductal adenocarcinoma (PDAC) patients.

METHOD

HABP1 expression was evaluated in 89 PDAC specimens.

RESULTS

The expression of HABP1 was significantly higher in tumor tissues than that in adjacent normal tissues. High nucleus HABP1 expression and high cytoplasm HABP1 expression were both detected in PDAC tissues. Overall survival analysis by optical density showed that the mean survival was similar between patients with low and high optical density values of HABP1 expression (P = 0.312). The similar result was also found between patients with low-moderate or high nucleus HABP1 expression (P = 0.275). However, the mean survival was significantly poorer in patients with cytoplasm HABP1 overexpression (P < 0.001). High cytoplasm HABP1 expression was strongly correlated with late tumor stages, arterial involvement, lymph node metastasis and carbohydrate antigen 19-9 levels.

CONCLUSION

High cytoplasm HABP1 expression may prove to be a predictor of poor survival and late tumor stage in PDAC patients. HABP1 could serve as a promising biomarker to identify subsets of PDAC patients with high malignant clinical behavior.

High molecular weight fibroblast growth factor 2 induces apoptosis by interacting with complement component 1 Q subcomponent-binding protein in vitro

Fibroblast growth factor 2 (FGF2) is a multifunctional cell growth factor that regulates cell proliferation, differentiation, adhesion, migration, and apoptosis. FGF2 has multiple isoforms, including an 18-kDa low molecular weight isoform (lo-FGF2) and 22-, 23-, 24-, and 34-kDa high molecular weight isoforms (hi-FGF2). Hi-FGF2 overexpression induces chromatin compaction, which requires the mitochondria and leads to apoptosis. Complement component 1 Q subcomponent-binding protein (C1QBP) plays an important role in mitochondria-dependent apoptosis by regulating the opening of the mitochondrial permeability transition pore. However, the interaction between C1QBP and hi-FGF2 and its role in hi-FGF2-mediated apoptosis remain unclear. Here, we found that hi-FGF2 overexpression induced depolarization of the mitochondrial membrane, cytochrome c release into the cytosol, and a considerable increase in C1QBP messenger RNA and protein expression. Furthermore, coimmunoprecipitation results showed that the mitochondrial protein, C1QBP, interacts with hi-FGF2. C1QBP knockdown using small interfering RNA significantly decreased the localization of hi-FGF2 to the mitochondria and increased the rate of apoptosis. Our results highlight a novel mechanism underlying hi-FGF2-induced, mitochondria-driven cell death involving the direct interaction between hi-FGF2 and C1QBP and the upregulation of C1QBP expression.

Multi-functional, multicompartmental hyaluronan-binding protein 1 (HABP1/p32/gC1qR): implication in cancer progression and metastasis

Cancer is a complex, multi-factorial, multi-stage disease and a global threat to human health. Early detection of nature and stage of cancer is highly crucial for disease management. Recent studies have proved beyond any doubt about the involvement of the ubiquitous, myriad ligand binding, multi-functional human protein, hyaluronan-binding protein 1 (HABP1), which is identical to the splicing factor associated protein (p32) and the receptor of the globular head of the complement component (gC1qR) in tumorigenesis and cancer metastasis. Simultaneously three laboratories have discovered and named this protein separately as mentioned. Subsequently, different scientists have worked on the distinct functions in cellular processes ranging from immunological response, splicing mechanism, sperm-oocyte interactions, cell cycle regulation to cancer and have concentrated in their respective area of interest, referring it as either p32 or gC1qR or HABP1. HABP1 overexpression has been reported in almost all the tissue-specific forms of cancer and correlated with stage and poor prognosis in patients. In order to tackle this deadly disease and for therapeutic intervention, it is imperative to focus on all the regulatory aspects of this protein. Hence, this work is an attempt to combine an assortment of information on this protein to have an overview, which suggests its use as a diagnostic marker for cancer. The knowledge might assist in the designing of drugs for therapeutic intervention of HABP1/p32/gC1qR regulated specific ligand mediated pathways in cancer.

Complement component 1, q subcomponent binding protein (C1QBP) in lipid rafts mediates hepatic metastasis of pancreatic cancer by regulating IGF-1/IGF-1R signaling

Pancreatic cancer shows a remarkable predilection for hepatic metastasis. Complement component 1, q subcomponent binding protein (C1QBP) can mediate growth factor-induced cancer cell chemotaxis and distant metastasis by activation of receptor tyrosine kinases. Coincidentally, insulin-like growth factor-1 (IGF-1) derived from the liver and cancer cells itself has been recognized as a critical inducer of hepatic metastasis. However, the mechanism underlying IGF-1-dependent hepatic metastasis of pancreatic cancer, in which C1QBP may be involved, remains unknown. In the study, we demonstrated a significant association between C1QBP expression and hepatic metastasis in patients with pancreatic cancer. IGF-1 induced the translocation of C1QBP from cytoplasm to lipid rafts and further drove the formation of CD44 variant 6 (CD44v6)/C1QBP complex in pancreatic cancer cells. C1QBP interacting with CD44v6 in lipid rafts promoted phosphorylation of IGF-1R and thus activated downstream PI3K and MAPK signaling pathways which mediated metastatic potential of pancreatic cancer cells including proliferation, apoptosis, invasion, adhesion and energy metabolism. Furthermore, C1QBP knockdown suppressed hepatic metastasis of pancreatic cancer cells in nude mice. We therefore conclude that C1QBP in lipid rafts serves a key regulator of IGF-1/IGF-1R-induced hepatic metastasis from pancreatic cancer. Our findings about C1QBP in lipid rafts provide a novel strategy to block IGF-1/IGF-1R signaling in pancreatic cancer and a reliable premise for more efficient combined modality therapies.

C1QBP is upregulated in colon cancer and binds to apolipoprotein A-I

The present study aimed to investigate the expression of complement component 1, q subcomponent-binding protein (C1QBP) in colon cancer cells, and identify proteins that interact with C1QBP. Total proteins were extracted from both the tumor and normal tissues of 22 patients with colon cancer and analyzed using liquid chromatography-mass spectrometry (LC-MS) to identify proteins that were differentially-expressed in tumor tissues. C1QBP overexpression was induced in 293T cells using a pFLAG-CMV2 expression vector. Overexpressed FLAG-tagged C1QBP protein was then immunoprecipitated using anti-FLAG antibodies and C1QBP-interacting proteins were screened using LC-MS analysis of the immunoprecipitates. The C1QBP-interacting proteins were confirmed using reverse-immunoprecipitation and the differential expression of C1QBP in tissues and cell lines was confirmed using western blot analysis. LC-MS analysis revealed that C1QBP exhibited a typical tumor expression pattern. Two immune-reactive signals (33 and 14 kDa) were detected in normal and tumor tissues from 19 patients. Furthermore, 14 kDa C1QBP protein was upregulated in the tumors of 15 patients. In total, 39 proteins were identified as candidate C1QBP-interacting proteins, and an interaction between C1QBP and apolipoprotein A-I was confirmed. The present study indicates that C1QBP is involved in colon cancer carcinogenesis, and that the mechanisms underlying the established anti-tumor properties of apolipoprotein A-I may include interacting with and inhibiting the activity of C1QBP.

Hyaluronic acid binding protein 1 overexpression is an indicator for disease-free survival in cervical cancer

BACKGOUND

Hyaluronic acid binding protein 1 (HABP1) is reported to overexpress in various cancer tissues and may therefore contribute to oncogenesis. However, the status of HABP1 expression in cervical cancer (CC) remains unknown. The aim of this study was to investigate the role of HABP1 and its relationship with clinical characteristics in patients with CC.

METHODS

Immunohistochemistry was used to explore the expression of HABP1 in 30 cervical intra-epithelial neoplasia (CIN) and 118 CC specimens compared to 10 normal cervical specimens.

RESULTS

HABP1 expression was found to be positively higher in CC than in CIN2/3 cases (P = 0.020). Moreover, clinicopathological analysis showed that HABP1 overexpression was associated with advanced FIGO stage (P = 0.001), poor histologic grade (P = 0.013), large tumor size (P = 0.025), LVSI (P = 0.024), deep stromal infiltration (P = 0.001), and lymph node metastasis (P = 0.023). Multivariate analysis suggested that HABP1 overexpression was an independent factor for disease-free survival (DFS) (hazard ratio 3.082; 95% confidence interval 1.372-7.501; P = 0.007).

CONCLUSIONS

The present data provide evidence that HABP1 overexpression predicts CC with high-risk factors and may therefore serve as a new molecular marker for the prediction of DFS in these patients.

Proteomics Analysis Reveals Novel RASSF2 Interaction Partners

RASSF2 is a tumor suppressor that shares homology with other Ras-association domain (RASSF) family members. It is a powerful pro-apoptotic K-Ras effector that is frequently inactivated in many human tumors. The exact mechanism by which RASSF2 functions is not clearly defined, but it likely acts as a scaffolding protein, modulating the activity of other pro-apoptotic effectors, thereby regulating and integrating tumor suppressor pathways. However, only a limited number of RASSF2 interacting partners have been identified to date. We used a proteomics based approach to identify additional RASSF2 interactions, and thereby gain a better insight into the mechanism of action of RASSF2. We identified several proteins, including C1QBP, Vimentin, Protein phosphatase 1G and Ribonuclease inhibitor that function in diverse biological processes, including protein post-translational modifications, epithelial-mesenchymal transition, cell migration and redox homeostasis, which have not previously been reported to interact with RASSF2. We independently validated two of these novel interactions, C1QBP and Vimentin and found that the interaction with C1QBP was enhanced by K-Ras whereas, interestingly, the Vimentin interaction was reduced by K-Ras. Additionally, RASSF2/K-Ras regulated the acetylation of Vimentin. Our data thus reveal novel mechanisms by which RASSF2 may exert its functions, several of which may be Ras-regulated.

LL-37-induced host cell cytotoxicity depends on cellular expression of the globular C1q receptor (p33)

It is unclear how human host cells cope with cytotoxic effects caused by the host-defence peptide (HDP) LL-37. Our findings show that LL-37-induced cytotoxicity is counteracted by intracellular p33, suggesting that p33 protects against deleterious activities of the innate immune system.

Overexpression of HABP1 correlated with clinicopathological characteristics and unfavorable prognosis in endometrial cancer

Hyaluronic acid binding protein 1 (HABP1/gC1qR/p32), a ubiquitous multifunctional protein belonging to the hyaladherin family, has been implicated in the tumorigenesis, progression, invasion, and metastasis of several malignant tumors. However, the role of HABP1 in endometrial cancer has not yet been studied. This study aimed to detect the expression of HABP1 in endometrial cancer and explore its role in the clinicopathological features and prognosis of endometrial cancer. We analyzed HABP1 expression by immunohistochemistry in 188 endometrial cancer specimens, 43 benign endometrial lesion specimens, and 41 normal endometrium specimens and assessed using Western blot analysis. Statistical analysis showed that HABP1 was overexpressed in endometrial cancer and benign endometrial lesion compared with normal endometrium (P < 0.001 and P = 0.012, respectively). In addition, HABP1 expression was significantly higher in endometrial cancer than in benign endometrial lesion (P < 0.001). High HABP1 expression was significantly associated with advanced International Federation of Gynecology and Obstetrics stage (P = 0.019), higher histologic grade (P < 0.001), deep myometrial invasion (P = 0.013), lymphovascular space invasion (P = 0.010), lymph node metastasis (P = 0.015), and recurrence (P = 0.009). Patients with high HABP1 expression had a poorer overall survival (OS) and disease-free survival (DFS) than patients with low HABP1 expression (P = 0.015 and P = 0.012, respectively). Multivariate Cox regression analysis showed that the HABP1 expression status was an independent prognostic factor of OS and DFS (P = 0.025 and P = 0.022, respectively) in patients with endometrial cancer. Our results indicated that overexpression of HABP1 may serve as a new biomarker to predict the progression and prognosis of endometrial cancer.

Increased hyaluronan levels in HABP1/p32/gC1qR overexpressing HepG2 cells inhibit autophagic vacuolation regulating tumor potency

Tumor growth and development is influenced by its microenvironment. A major extracellular matrix molecule involved in cancer progression is hyaluronan (HA). Hyaluronan and expression of a number of hyaladherin family proteins are dramatically increased in many cancer malignancies. One such hyaladherin, hyaluronan-binding protein 1 (HABP1/p32/gC1qR) has been considered to be a biomarker for tumor progression. Interestingly, overexpression of HABP1 in fibroblast has been shown to increase autophagy via generation of excess reactive oxygen species (ROS) and depletion of HA leading to apoptosis. Cancerous cells are often found to exhibit decreased rate of proteolysis/autophagy in comparison to their normal counterparts. To determine if HABP1 levels alter tumorigenicity of cancerous cells, HepR21, the stable transfectant overexpressing HABP1 in HepG2 cell line was derived. HepR21 has been shown to have increased proliferation rate than HepG2, intracellular HA cable formation and enhanced tumor potency without any significant alteration of intracellular ROS. In this paper we have observed that HepR21 cells containing higher endogenous HA levels, have downregulated expression of the autophagic marker, MAP-LC3, consistent with unaltered levels of endogenous ROS. In fact, HepR21 cells seem to have significant resistance to exogenous ROS stimuli and glutathione depletion. HepR21 cells were also found to be more resilient to nutrient starvation in comparison to its parent cell line. Decline in intracellular HA levels and HA cables in HepR21 cells upon treatment with HAS inhibitor (4-MU), induced a surge in ROS levels leading to increased expression of MAP-LC3 and tumor suppressors Beclin 1 and PTEN. This suggests the importance of HABP1 induced HA cable formation in enhancing tumor potency by maintaining the oxidant levels and subsequent autophagic vacuolation.

Screening of differentially expressed genes related to bladder cancer and functional analysis with DNA microarray

OBJECTIVE

The purpose of this study was to identify genes related to bladder cancer with samples from normal and disease cases by microarray chip.

METHODS

After downloading the gene expression profile GSE3167 from Gene Expression Omnibus database which includes 50 bladder samples, comprising 9 normal and 41 disease samples, differentially expressed genes were identified with packages in R language. The selected differentially expressed genes were further analyzed using bioinformatics methods. Firstly, molecular functions, biological processes and cell component analysis were researched by software Gestalt. Then, software String was used to search interaction relationships among differentially expressed genes, and hub genes of the network were selected. Finally, by using plugins of software Cytoscape, Mcode and Bingo, module analysis of hub-genes was performed.

RESULTS

A total of 221 genes were identified as differentially expressed by comparing normal and disease bladder samples, and a network as well as the hub gene C1QBP was obtained from the network. The C1QBP module had the closest relationship to production of molecular mediators involved in inflammatory responses.

CONCLUSION

We obtained differentially expressed genes of bladder cancer by microarray, and both PRDX2 and YWHAZ in the module with hub gene C1QBP were most significantly related to production of molecular mediators involved in inflammatory responses. From knowledge of inflammatory responses and cancer, our results showed that, the hub gene and its module could induce inflammation in bladder cancer. These related genes are candidate bio-markers for bladder cancer diagnosis and might be helpful in designing novel therapies.

p32 protein levels are integral to mitochondrial and endoplasmic reticulum morphology, cell metabolism and survival

p32 [also known as HABP1 (hyaluronan-binding protein 1), gC1qR (receptor for globular head domains complement 1q) or C1qbp (complement 1q-binding protein)] has been shown previously to have both mitochondrial and non-mitochondrial localization and functions. In the present study, we show for the first time that endogenous p32 protein is a mitochondrial protein in HeLa cells under control and stress conditions. In defining the impact of altering p32 levels in these cells, we demonstrate that the overexpression of p32 increased mitochondrial fibrils. Conversely, siRNA-mediated p32 knockdown enhanced mitochondrial fragmentation accompanied by a loss of detectable levels of the mitochondrial fusion mediator proteins Mfn (mitofusin) 1 and Mfn2. More detailed ultrastructure analysis by transmission electron microscopy revealed aberrant mitochondrial structures with less and/or fragmented cristae and reduced mitochondrial matrix density as well as more punctate ER (endoplasmic reticulum) with noticeable dissociation of their ribosomes. The analysis of mitochondrial bioenergetics showed significantly reduced capacities in basal respiration and oxidative ATP turnover following p32 depletion. Furthermore, siRNA-mediated p32 knockdown resulted in differential stress-dependent effects on cell death, with enhanced cell death observed in the presence of hyperosmotic stress or cisplatin treatment, but decreased cell death in the presence of arsenite. Taken together, our studies highlight the critical contributions of the p32 protein to the morphology of mitochondria and ER under normal cellular conditions, as well as important roles of the p32 protein in cellular metabolism and various stress responses.

Elevated expression of hyaluronic acid binding protein 1 (HABP1)/P32/C1QBP is a novel indicator for lymph node and peritoneal metastasis of epithelial ovarian cancer patients

The present study aims to clarify whether hyaluronan binding protein 1 (HABP1/p32/C1QBP) is an indicator of peritoneal and lymph node metastasis in epithelial ovarian cancer (EOC), which to the authors' knowledge is not previously reported by others. Western blot analysis demonstrated that HABP1 was highly overexpressed in most metastatic lesions. Of 89 patients whose primary tumors showed high HABP1 expression on immunohistochemical staining, 85 (95.5%) presented peritoneal metastases and 43 (48.3%) had lymph node metastases. Univariate and multivariate logistic regression analyses revealed that HABP1 overexpression correlated with peritoneal dissemination and lymph node metastasis in EOC. The specificity and positive predictive value of HABP1 staining were shown to be better for peritoneal metastasis, while the negative and sensitivity predictive value of HABP1 staining were better for lymph node metastasis. The odds ratio of high versus low staining for peritoneal spread was 9.236 (95% confidence interval (CI), 2.705, 19.316), and that for lymph node metastasis was 8.614 (95% CI, 2.507, 21.039). Furthermore, HABP1 protein may potentially be used alone or in combination with other markers as a predictive marker of EOC patients with lymph node metastasis and/or peritoneal dissemination.

Effects of intratumoral administration of a hyaluronan-cisplatin nanoconjugate to five dogs with soft tissue sarcomas

OBJECTIVE

To determine the effects of intratumoral injection of a hyaluronan-cisplatin nanoconjugate on local and systemic platinum concentrations and systemic toxicosis.

ANIMALS

5 dogs with spontaneous soft tissue sarcomas (STSs).

PROCEDURES

For each dog, approximately 1.5 mL of hyaluronan nanocarrier conjugated with 20 mg of cisplatin was injected into an external STS. Blood samples were collected immediately before (0 hours) and at 0.5, 1, 2, 3, 4, 24, and 96 hours after hyaluronan-cisplatin injection for pharmacokinetic analyses. Urine samples were obtained at 0 and at 96 hours after hyaluronan-cisplatin injection for urinalysis. Each treated STS and its sentinel lymph nodes were surgically removed 96 hours after the hyaluronan-cisplatin injection. Inductively coupled plasma mass spectrometry was used to measure platinum concentrations in blood samples, tumors, and lymph nodes.

RESULTS

No tissue reactions were detected 96 hours after hyaluronan-cisplatin injection. Mean ± SD area under the curve, peak concentration, and terminal half-life for unbound (plasma) and total (serum) platinum were 774.6 ± 221.1 ng•h/mL and 3,562.1 ± 2,031.1 ng•h/mL, 56.5 ± 20.9 ng/mL and 81.6 ± 40.4 ng/mL, and 33.6 ± 16.1 hours and 51.2 ± 29.1 hours, respectively. Platinum concentrations ranged from 3,325 to 8,229 ng/g in STSs and 130 to 6,066 ng/g in STS-associated lymph nodes.

CONCLUSIONS AND CLINICAL RELEVANCE

Intratumoral injection of the hyaluronan-cisplatin nanoconjugate was well tolerated in treated dogs. Following intratumoral hyaluronan-cisplatin injection, platinum concentration was 1,000-fold and 100-fold greater within treated tumors and tumor-draining lymphatics, respectively, compared with that in plasma.

A calreticulin/gC1qR complex prevents cells from dying: a conserved mechanism from arthropods to humans

The crossroad between cell death and proliferation is a general target for viral infections because viruses need to obstruct apoptosis to use cells for their own replication. Inducing immunogenic cell death in proliferating cells is also an important aim of anticancer chemotherapy. The C1q-binding proteins calreticulin (CRT) and gC1qR are highly conserved ubiquitous proteins, which are putative targets for viral manipulation and are associated with cancer. Here we show that these proteins form a complex in the cytoplasm as a response to viral infection resulting in apoptosis prevention. The formation of a cytosolic CRT/gC1qR complex prevents cell death by reducing gC1qR translocation into the mitochondria, and we provide evidence that this mechanism is conserved from arthropods to human cancer cells. Furthermore, we show that it is possible to prevent this complex from being formed in cancer cells. When the peptides of the complex proteins are overexpressed in these cells, the cells undergo apoptosis. This finding shows a causal link between virus and cancer and may be used to develop new tools in anticancer or antiviral therapy.

The globular heads of the C1q receptor regulate apoptosis in human cervical squamous carcinoma cells via a p53-dependent pathway

Background

The globular heads of the human C1q receptor (gC1qR) localize predominantly to the mitochondrial matrix. gC1qR mediates many biological responses, including growth perturbation, morphological abnormalities and the initiation of apoptosis. The purpose of this study was to investigate the relationship between mitochondrial dysfunction, p53 status and gC1qR expression and the regulation of apoptosis in human cervical squamous carcinoma cells (C33a and SiHa).

Methods

Here, gC1qR expression was examined in human cervical tissues using real-time PCR and Western blot analysis. Apoptotic death of C33a and SiHa cells was assessed by flow cytometric analysis that detected the subG1 population. Mitochondrial function was assessed via ROS generation, the content of cytosolic Ca²⁺, and the change in mitochondrial membrane potential (Δψm). The viability and migration of C33a and SiHa cells were detected via the water-soluble tetrazolium salt (WST-1) assay and the transwell assay, respectively.

Results

gC1qR expression was decreased in cervical squamous cell carcinoma tissues compared with normal tissues. C33a and SiHa cells transfected with a vector encoding gC1qR displayed mitochondrial dysfunction and apoptosis, which was abrogated by the addition of a mutant form of p53 or p53 small interference RNA (siRNA). Furthermore, upon overexpression of gC1qR, cell viability and migration were significantly enhanced, and the apoptosis of C33a and SiHa cells were decreased when cells were treated with mutant p53 or p53 siRNA.

Conclusions

These data support a mechanism whereby gC1qR induces apoptosis through the mitochondrial and p53-dependent pathways in cervical squamous cell carcinoma.

Significance of hyaluronan binding protein (HABP1/P32/gC1qR) expression in advanced serous ovarian cancer patients

BACKGROUND

To evaluate various risk factors related to the overall survival (OS) and progression free survival (PFS) in 131 patients with stage III-IV ovarian serous carcinoma.

METHODS

All patients underwent primary debulking surgery followed by a standard chemotherapeutic treatment regimen. Hyaluronan binding protein (HABP1) expression was evaluated using immunohistochemical-staining and assessed using western-immunoblotting analyses. A log-rank test was used to compare OS and PFS between cisplatin sensitive versus resistant patients. Multivariate analyses were used to identify risk factors associated with OS and PFS.

RESULTS

HABP1 over-expression was correlated to histological-differentiation, residual-tumor-size, serum CA-125 levels and International Federation of Gynecology and Obstetrics (FIGO) stage. Multivariate analyses demonstrated that increased expression of HABP1 was associated with cisplatin resistance. HABP1 low-expression resulted in an increased five-year OS and PFS. Cox proportional hazards test identified that high expression of HABP1 led to increased risk for stage III/IV serous ovarian cancer via poor OS and PFS. This was similar for cisplatin resistant patients. Thus, increased HABP1 immunoreactivity in ovarian cancer may lead to a shortening in disease-free intervals of patients.

CONCLUSION

HAPBP1 over-expression in primary ovarian carcinomas is related to a decrease in OS and PFS and may be utilized as a prognostic marker for stage III/IV patients.

The mitochondrial protein C1qbp promotes cell proliferation, migration and resistance to cell death

Complement 1q-Binding Protein (C1qbp) is a mitochondrial protein reported to be upregulated in cancer. However, whether C1qbp plays a tumor suppressive or tumorigenic role in the progression of cancer is controversial. Moreover, the exact effects of C1qbp on cell proliferation, migration, and death/survival have not been definitely proven. To this end, we comprehensively examined the effects of C1qbp on mitochondrial-dependent cell death, proliferation, and migration in both normal and breast cancer cells using genetic gain- and loss-of-function approaches. In normal fibroblasts, overexpression of C1qbp protected the cells against staurosporine-induce apoptosis, increased proliferation, decreased cellular ATP, and increased cell migration in a wound-healing assay. In contrast, the opposite effects were observed in fibroblasts depleted of C1qbp by RNA interference. C1qbp expression was found to be markedly elevated in 4 different human breast cancer cell lines as well as in ductal and adenocarcinoma tumors from breast cancer patients. Stable knockdown of C1qbp by shRNA in the aggressive MDA-MB-231 breast cancer cell line greatly reduced cell proliferation, increased ATP levels, and decreased cell migration compared to control shRNA-transfected cells. Moreover, C1qbp knockdown elicited a significant increase in doxorubicin-induced apoptosis in the MDA-MB-231 cells. Finally, C1qbp upregulation was not restricted to breast cancer cells and tumors, as levels of C1qbp were also found to be significantly elevated in both human lung and colon cancer cell lines and carcinomas. Together, these results establish a pro-tumor, rather than anti-tumor, role for C1qbp, and indicate that C1qbp could serve as a molecular target for cancer therapeutics.

Hyaluronan as an immune regulator in human diseases

Accumulation and turnover of extracellular matrix components are the hallmarks of tissue injury. Fragmented hyaluronan stimulates the expression of inflammatory genes by a variety of immune cells at the injury site. Hyaluronan binds to a number of cell surface proteins on various cell types. Hyaluronan fragments signal through both Toll-like receptor (TLR) 4 and TLR2 as well as CD44 to stimulate inflammatory genes in inflammatory cells. Hyaluronan is also present on the cell surface of epithelial cells and provides protection against tissue damage from the environment by interacting with TLR2 and TLR4. Hyaluronan and hyaluronan-binding proteins regulate inflammation, tissue injury, and repair through regulating inflammatory cell recruitment, release of inflammatory cytokines, and cell migration. This review focuses on the role of hyaluronan as an immune regulator in human diseases.

Involvement of p32 and microtubules in alteration of mitochondrial functions by rubella virus

The interaction of the rubella virus (RV) capsid (C) protein and the mitochondrial p32 protein is believed to participate in virus replication. In this study, the physiological significance of the association of RV with mitochondria was investigated by silencing p32 through RNA interference. It was demonstrated that downregulation of p32 interferes with microtubule-directed redistribution of mitochondria in RV-infected cells. However, the association of the viral C protein with mitochondria was not affected. When cell lines either pretreated with respiratory chain inhibitors or cultivated under (mild) hypoxic conditions were infected with RV, viral replication was reduced in a time-dependent fashion. Additionally, RV infection induces increased activity of mitochondrial electron transport chain complex III, which was associated with an increase in the mitochondrial membrane potential. These effects are outstanding among the examples of mitochondrial alterations caused by viruses. In contrast to the preferential localization of p32 to the mitochondrial matrix in most cell lines, RV-permissive cell lines were characterized by an almost exclusive membrane association of p32. Conceivably, this contributes to p32 function(s) during RV replication. The data presented suggest that p32 fulfills an essential function for RV replication in directing trafficking of mitochondria near sites of viral replication to meet the energy demands of the virus.

Inhibition of pathogen-induced apoptosis by a Coxiella burnetii type IV effector protein

Coxiella burnetii and Legionella pneumophila are evolutionarily related pathogens with different intracellular infection strategies. C. burnetii persists within and is transmitted by mammalian hosts, whereas, L. pneumophila is found primarily in the environment associated with protozoan hosts. Although a type IV secretion system encoded by the defect in organelle trafficking (dot) and intracellular multiplication (icm) genes is a virulence determinant that remains highly conserved in both bacteria, the two pathogens encode a different array of effector proteins that are delivered into host cells by the Dot/Icm machinery. This difference suggests that adaptations to evolutionarily distinct hosts may be reflected in the effector protein repertoires displayed by these two pathogens. Here we provide evidence in support of this hypothesis. We show that a unique C. burnetii effector from the ankyrin repeat (Ank) family called AnkG interferes with the mammalian apoptosis pathway. AnkG was found to interact with the host protein gC1qR (p32). Either the addition of AnkG to the repertoire of L. pneumophila effector proteins or the silencing of p32 in mouse dendritic cells resulted in a gain of function that allowed intracellular replication of L. pneumophila in these normally restrictive mammalian host cells by preventing rapid pathogen-induced apoptosis. These data indicate that p32 regulates pathogen-induced apoptosis and that AnkG functions to block this pathway. Thus, emergence of an effector protein that interferes with a proapoptotic signaling pathway directed against intracellular bacteria correlates with adaptation of a pathogen to mammalian hosts.

Increased expression of hyaluronic acid binding protein 1 is correlated with poor prognosis in patients with breast cancer

BACKGROUND AND OBJECTIVES

Hyaluronic acid binding protein 1 (HABP1), a family of proteins interacting with hyaluronan (HA), had been associated with cell adhesion and tumor invasion. The aim of this study was to investigate the correlation between clinicopathologic factors and patient survival time with the expression of HABP1 in breast cancer patients.

METHODS

Expression of HABP1 mRNA and protein were detected with real-time quantitative PCR and immunohistochemical staining in 63 breast cancer and non-cancerous matched tissues.

RESULTS

The mRNA expression level of HABP1 was unrelated to the patient's age, tumor size, histological grade, TNM stage. However, it proved to be positively related to axillary nodes metastasis (P = 0.008). Furthermore, it was shown that the survival rate of patients with low HABP1 expression was significantly higher than that of patients with high HABP1 expression (P = 0.025). Multivariate analysis revealed that HABP1 mRNA expression level was a significant factor for predicting prognosis (P = 0.022). The immunohistochemistry results showed that the expression level of HABP1 in breast cancer cells was higher than that in normal breast cells.

CONCLUSION

HABP1 might be an independent predictive factor for breast cancer prognosis and up-regulation of HABP1 might play an important role in the metastasis of breast cancer.

miR-375 maintains normal pancreatic alpha- and beta-cell mass

Altered growth and development of the endocrine pancreas is a frequent cause of the hyperglycemia associated with diabetes. Here we show that microRNA-375 (miR-375), which is highly expressed in pancreatic islets, is required for normal glucose homeostasis. Mice lacking miR-375 (375KO) are hyperglycemic, exhibit increased total pancreatic alpha-cell numbers, fasting and fed plasma glucagon levels, and increased gluconeogenesis and hepatic glucose output. Furthermore, pancreatic beta-cell mass is decreased in 375KO mice as a result of impaired proliferation. In contrast, pancreatic islets of obese mice (ob/ob), a model of increased beta-cell mass, exhibit increased expression of miR-375. Genetic deletion of miR-375 from these animals (375/ob) profoundly diminished the proliferative capacity of the endocrine pancreas and resulted in a severely diabetic state. Bioinformatic analysis of transcript data from 375KO islets revealed that miR-375 regulates a cluster of genes controlling cellular growth and proliferation. These data provide evidence that miR-375 is essential for normal glucose homeostasis, alpha- and beta-cell turnover, and adaptive beta-cell expansion in response to increasing insulin demand in insulin resistance.

Mitochondrial p32 is a critical mediator of ARF-induced apoptosis

The shared exon 2 of the p14ARF-p16INK4a locus is frequently mutated in human cancers. However, in contrast to the exon 1beta-encoded N-terminal half of ARF, the function of the exon 2-encoded C-terminal half of ARF has been elusive. Here, we report that the mitochondrial protein p32/C1QBP binds the ARF C terminus. We show that p32 is required for ARF to localize to mitochondria and induce apoptosis, and that ARF mutations specifically disrupting p32 binding can impair both of these functions. Wild-type ARF, but not a p32-binding-deficient ARF mutant, localizes to mitochondria, reduces mitochondrial membrane potential, and sensitizes cells to p53-induced apoptosis. These findings provide a potential explanation for the frequent human cancer mutations targeting the ARF C terminus.

Excessive reactive oxygen species induces apoptosis in fibroblasts: role of mitochondrially accumulated hyaluronic acid binding protein 1 (HABP1/p32/gC1qR)

Constitutively expressed HABP1 in normal murine fibroblast cell line induces growth perturbation, morphological abnormalities along with initiation of apoptosis. Here, we demonstrate that though HABP1 accumulation started in mitochondria from 48 hr of growth, induction of apoptosis with the release of cytochrome c and apoptosome complex formation occurred only after 60 hr. This mitochondrial dysfunction was due to gradual increase in ROS generation in HABP1 overexpressing cells. Along with ROS generation, increased Ca 2+ influx in mitochondria leading to drop in membrane potential was evident. Interestingly, upon expression of HABP1, the respiratory chain complex I was shown to be significantly inhibited. Electronmicrograph confirmed defective mitochondrial ultrastructure. The reduction in oxidant generation and drop in apoptotic cell population accomplished by disruption of HABP1 expression, corroborating the fact that excess ROS generation in HABP1 overexpressing cells leading to apoptosis was due to mitochondrial HABP1 accumulation.