Versican-Derived Matrikines Regulate Batf3-Dendritic Cell Differentiation and Promote T Cell Infiltration in Colorectal Cancer

Colorectal cancer originates within immunologically complex microenvironments. To date, the benefits of immunotherapy have been modest, except in neoantigen-laden mismatch repair-deficient tumors. Approaches to enhance tumor-infiltrating lymphocytes in the tumor bed may substantially augment clinical immunotherapy responses. In this article, we report that proteolysis of the tolerogenic matrix proteoglycan versican (VCAN) strongly correlated with CD8⁺ T cell infiltration in colorectal cancer, regardless of mismatch repair status. Tumors displaying active VCAN proteolysis and low total VCAN were associated with robust (10-fold) CD8⁺ T cell infiltration. Tumor-intrinsic WNT pathway activation was associated with CD8⁺ T cell exclusion and VCAN accumulation. In addition to regulating VCAN levels at the tumor site, VCAN proteolysis results in the generation of bioactive fragments with novel functions (VCAN-derived matrikines). Versikine, a VCAN-derived matrikine, enhanced the generation of CD103⁺CD11c^hiMHCII^hi conventional dendritic cells (cDCs) from Flt3L-mobilized primary bone marrow-derived progenitors, suggesting that VCAN proteolysis may promote differentiation of tumor-seeding DC precursors toward IRF8- and BATF3-expressing cDCs. Intratumoral BATF3-dependent DCs are critical determinants for T cell antitumor immunity, effector T cell trafficking to the tumor site, and response to immunotherapies. Our findings provide a rationale for testing VCAN proteolysis as a predictive and/or prognostic immune biomarker and VCAN-derived matrikines as novel immunotherapy agents.

Abstract 160: Cardiomyocyte CaMKII Mediates Expression of Pro-inflammatory Chemokines and Cytokines, Macrophage Infiltration and Cardiac Remodeling in Response to Pressure Overload

Background: There is evidence that inflammation is associated with pressure overload induced cardiac remodeling and heart failure, as well as evidence for a role of CaMKII in remodeling and heart failure development. Whether CaMKII mediates inflammatory responses that contribute to its role in adverse remodeling following TAC has not been established.

Methods and Results: CaMKIIδ knockout (CKO) mice in which CaMKIIδ was selectively deleted from cardiomyocytes were subjected to pressure overload by transverse aortic constriction (TAC). By 3 days, the earliest time examined, there were marked increases in cardiac mRNA levels for pro-inflammatory chemokines CCL2 (MCP-1, ~15 fold), CCL3 (MIP1α, ~20 fold) and cytokines (IL-6, ~50 fold). These responses were markedly attenuated (by 56%, 43% and 42 % respectively) in the CKO mice. NFkB signaling was also increased in control heart at 3 days of TAC but not in CKO. Immunohistochemical analysis showed increases in CD68+ macrophage by 7 days TAC which further increased by 14days of TAC. Macrophages accumulation was also significantly attenuated in the CKO mice (50% decrease at 7day, 40% decrease at 14 days). Fibrosis was assessed by Masson trichrome staining and increases in collagen gene expression (col1a1 and col3a1 mRNA). Both were clearly elevated after 14 and 28 days TAC and significantly attenuated in the CKO mice.

Conclusion: Our results indicate that activation of CaMKII localized in cardiomyocytes initiates an inflammatory transcriptional program within cardiomyocyte. We suggest that this drives immune cell recruitment and is in turn associated with development of fibrosis. Early inflammatory responses and their sequelae may thus be responsible for involvement of CaMKII in the progression from hypertrophy to heart failure.

Abstract 313: Sphingosine-1-Phosphate and RhoA Signaling Regulate Dynamin-Related Protein 1 and Cardiac Mitochondrial Fission

In cardiomyocytes, signaling through RhoA is protective against ischemia/reperfusion injury. Cardioprotective receptor agonists such as sphingosine-1-phosphate (S1P) provide protection through RhoA activation. Mitochondrial fission has been suggested to play a role in cardioprotection, allowing for selective degradation of smaller damaged mitochondria. Our previous studies showed that RhoA signaling can protect cardiomyocytes against ischemia/reperfusion injury by blocking mitochondrial death pathways under oxidative stress, however it is not known if RhoA activation also regulates mitochondrial quality control. We tested the possibility that activated RhoA regulates cardiac mitochondrial fission. Adenoviral expression of constitutively active RhoA in cardiomyocytes caused an increase in small, fragmented mitochondria observed by both fluorescent confocal microscopy and electron microscopy. This mitochondrial fission phenotype was attenuated by inhibition of the downstream RhoA target Rho-associated Protein Kinase (ROCK), or by siRNA knockdown of the primary fission protein Dynamin-related Protein 1 (Drp1). Activated Drp1 causes mitochondrial fission when it translocates from the cytosol to the mitochondria, a process regulated by Drp1 phosphorylation. We determined that expression of active RhoA in cardiomyocytes stimulated phosphorylation of Drp1 at serine-616, and increased mitochondrial levels of Drp1. Both phosphorylation and mitochondrial translocation of Drp1 by active RhoA could be blocked by ROCK inhibition. Endogenous RhoA activation by S1P also increased Drp1 phosphorylation and mitochondrial translocation in a RhoA-dependent and ROCK-dependent mechanism. In conclusion, RhoA activation in cardiomyocytes can increase Drp1 phosphorylation and Drp1 mitochondrial localization, and induce mitochondrial fission. We propose that mitochondrial fission, elicited in response to increased availability of S1P and activation of RhoA in response to ischemia/reperfusion injury, represents a previously unknown pathway for cardioprotection.

Versican proteolysis as a key regulator of CD8+ T-cell infiltration in colorectal cancer

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Background: Colorectal cancer (CRC) originates within immunologically complex microenvironments. To date the benefits of immunotherapy have been modest except in neoantigen-laden mismatch repair (MMR)-deficient tumors. Approaches to enhance tumor-infiltrating lymphocytes (TILS) in the tumor bed may substantially augment clinical immunotherapy responses. Proteolysis of the tolerogenic matrix proteoglycan versican (VCAN) generates a bioactive fragment, versikine, with putative immunostimulatory activities. Methods: Matched normal and CRC tissue samples were collected from 122 patients with cancers across all stages and locations throughout the colon and rectum. These samples were stained for VCAN, αDPEAAE (neoepitope generated in cleaving VCAN to versikine), and CD8 and scored by a pathologist. Tumors were classified as VCAN proteolysis-predominant (VPP) if their staining for total VCAN staining intensity was < 1+ and staining for VCAN proteolysis (αDPEAAE antibody) was > 2. Conversely, tumors were classified as VCAN proteolysis-weak (VPW) if intact VCAN staining intensity was > 1+ or αDPEAAE intensity was < 2+. IHC for mismatch repair (MMR) proteins was also performed. Results: Overall increased VCAN staining was observed in cancer versus (vs) normal tissue. VPP tumors had a 10 fold greater infiltration of CD8+ T-cells vs VPW cancers (p < 0.001). The correlation between VCAN proteolysis and CD8+ T-cell infiltration was maintained in both cancers with proficient (p) MMR and deficient (d) MMR. In both pMMR and dMMR, the VPP tumors had the greatest degree of CD8+ T-cell infiltration (Wilcoxon rank sum tests: pMMR p = 0.006; dMMR p = 0.03). Among the VPP tumors there was a greater degree of CD8+ T cell infiltration in the dMMR cancers vs pMMR cancers (35 versus 14.8 TILs per high power filed, p = 0.04). Nuclear CTNNB1, a marker for activation of WNT signaling, negatively correlated with CD8+ T cell infiltration( p = 0.014). In addition, VCAN accumulation correlated with the presence of nuclear CTNNB1 (p < 0.001) Conclusions: This is the first description indicating that VCAN proteolysis may shape CRC immune contexture and provide a rationale for testing VCAN proteolysis as a predictive and/or prognostic immune biomarker.

Pathological changes of adipose tissue in secondary lymphoedema

BACKGROUND

The pathophysiology of lymphoedema is poorly understood. Current treatment options include compression therapy, resection, liposuction and lymphatic microsurgery, but determining the optimal treatment approach for each patient remains challenging.

OBJECTIVES

We characterized skin and adipose tissue alterations in the setting of secondary lymphoedema.

METHODS

Morphological and histopathological evaluations were conducted for 70 specimens collected from 26 female patients with lower-extremity secondary lymphoedema following surgical intervention for gynaecological cancers. Indocyanine green lymphography was performed for each patient to assess lymphoedema severity.

RESULTS

Macroscopic and ultrasound findings revealed that lymphoedema adipose tissue had larger lobules of adipose tissue, with these lobules surrounded by thick collagen fibres and interstitial lymphatic fluid. In lymphoedema specimens, adipocytes displayed hypertrophic changes and more collagen fibre deposits when examined using electron microscopy, whole-mount staining and immunohistochemistry. The number of capillary lymphatic channels was also found to be increased in the dermis of lymphoedema limbs. Crown-like structures (dead adipocytes surrounded by M1 macrophages) were less frequently seen in lymphoedema samples. Flow cytometry revealed that, among the cellular components of adipose tissue, adipose-derived stem/stromal cells and M2 macrophages were decreased in number in lymphoedema adipose tissue compared with normal controls.

CONCLUSIONS

These findings suggest that long-term lymphatic volume overload can induce chronic tissue inflammation, progressive fibrosis, impaired homeostasis, altered remodelling of adipose tissue, impaired regenerative capacity and immunological dysfunction. Further elucidation of the pathophysiological mechanisms underlying lymphoedema will lead to more reliable therapeutic strategies.

Nuclear Import of JAK1 Is Mediated by a Classical NLS and Is Required for Survival of Diffuse Large B-cell Lymphoma

JAKs are non-receptor tyrosine kinases that are generally found in association with cytokine receptors. In the canonical pathway, roles of JAKs have well been established in activating STATs in response to cytokine stimulation to modulate gene transcription. In contrast, a noncanonical role of JAK2 has recently been discovered, in which JAK2 in the nucleus imparts the epigenetic regulation of gene transcription through phosphorylation of tyrosine 41 on the histone protein H3. Recent work further demonstrated that this noncanonical mechanism is conserved with JAK1, which is activated by the autocrine cytokines IL6 and IL10 in activated B-cell-like diffuse large B-cell lymphoma (ABC DLBCL), a cancer type that is particularly difficult to treat and has poor prognosis. However, how JAK1 gains access to the nucleus to enable epigenetic regulation remains undefined. Here, we investigated this question and revealed that JAK1 has a classical nuclear localization signal toward the N-terminal region, which can be recognized by multiple importin α isoforms. Moreover, the nuclear import of JAK1 is independent of its kinase activity but is required for the optimal expansion of ABC DLBCL cells in vitroImplications: This study demonstrates that the nuclear import of JAK1 is essential for the optimal fitness of ABC DLBCL cells, and targeting JAK1 nuclear localization is a potential therapeutic strategy for ABC DLBCL. Mol Cancer Res; 15(3); 348-57. ©2016 AACR.

Selective coupling of the S1P3 receptor subtype to S1P-mediated RhoA activation and cardioprotection

Sphingosine-1-phosphate (S1P), a bioactive lysophospholipid, is generated and released at sites of tissue injury in the heart and can act on S1P1, S1P2, and S1P3 receptor subtypes to affect cardiovascular responses. We established that S1P causes little phosphoinositide hydrolysis and does not induce hypertrophy indicating that it does not cause receptor coupling to Gq. We previously demonstrated that S1P confers cardioprotection against ischemia/reperfusion by activating RhoA and its downstream effector PKD. The S1P receptor subtypes and G proteins that regulate RhoA activation and downstream responses in the heart have not been determined. Using siRNA or pertussis toxin to inhibit different G proteins in NRVMs we established that S1P regulates RhoA activation through Gα13 but not Gα12, Gαq, or Gαi. Knockdown of the three major S1P receptors using siRNA demonstrated a requirement for S1P3 in RhoA activation and subsequent phosphorylation of PKD, and this was confirmed in studies using isolated hearts from S1P3 knockout (KO) mice. S1P treatment reduced infarct size induced by ischemia/reperfusion in Langendorff perfused wild-type (WT) hearts and this protection was abolished in the S1P3 KO mouse heart. CYM-51736, an S1P3-specific agonist, also decreased infarct size after ischemia/reperfusion to a degree similar to that achieved by S1P. The finding that S1P3 receptor- and Gα13-mediated RhoA activation is responsible for protection against ischemia/reperfusion suggests that selective targeting of S1P3 receptors could provide therapeutic benefits in ischemic heart disease.

CaMKIIδ subtypes differentially regulate infarct formation following ex vivo myocardial ischemia/reperfusion through NF-κB and TNF-α

Deletion of Ca2+/calmodulin-dependent protein kinase II delta (CaMKIIδ) has been shown to protect against in vivo ischemia/reperfusion (I/R) injury. It remains unclear which CaMKIIδ isoforms and downstream mechanisms are responsible for the salutary effects of CaMKIIδ gene deletion. In this study we sought to compare the roles of the CaMKIIδB and CaMKIIδC subtypes and the mechanisms by which they contribute to ex vivo I/R damage. WT, CaMKIIδKO, and mice expressing only CaMKIIδB or δC were subjected to ex vivo global ischemia for 25min followed by reperfusion. Infarct formation was assessed at 60min reperfusion by triphenyl tetrazolium chloride (TTC) staining. Deletion of CaMKIIδ conferred significant protection from ex vivo I/R. Re-expression of CaMKIIδC in the CaMKIIδKO background reversed this effect and exacerbated myocardial damage and dysfunction following I/R, while re-expression of CaMKIIδB was protective. Selective activation of CaMKIIδC in response to I/R was evident in a subcellular fraction enriched for cytosolic/membrane proteins. Further studies demonstrated differential regulation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling and tumor necrosis factor alpha (TNF-α) expression by CaMKIIδB and CaMKIIδC. Selective activation of CaMKIIδC was also observed and associated with NF-κB activation in neonatal rat ventricular myocytes (NRVMs) subjected to oxidative stress. Pharmacological inhibition of NF-κB or TNF-α significantly ameliorated infarct formation in WT mice and those that re-express CaMKIIδC, demonstrating distinct roles for CaMKIIδ subtypes in I/R and implicating acute activation of CaMKIIδC and NF-κB in the pathogenesis of reperfusion injury.

One-hour plasma glucose as a predictor of the development of Type 2 diabetes in Japanese adults

AIMS

To test the hypothesis that 1-h plasma glucose in an oral glucose tolerance test is a better predictor of the development of diabetes than 2-h plasma glucose, independently of indices of insulin secretion or action in Japanese adults.

METHODS

A historical cohort study was conducted in 1445 Japanese workers who did not have diabetes. The association between 1-h plasma glucose and the development of Type 2 diabetes was analysed.

RESULTS

Overall, 95 of the study participants developed Type 2 diabetes during a mean follow-up of 4.5 years. The area under the receiver-operating characteristic curve for 1-h plasma glucose for future diabetes [0.88 (95% CI 0.84-0.91)] was greater than that for 2-h plasma glucose [0.79 (95% CI 0.74-0.84)], and for insulinogenic [0.73 (95% CI 0.68-0.78)] and disposition indices [0.79 (95% CI 0.74-0.84); P < 0.05]. Compared with the first quartile, the hazard ratio for future diabetes in the fourth quartile of 1-h plasma glucose was 42.5 [95% CI 5.7-315.2 (P < 0.05)] and the hazard ratio in the fourth quartile of 2-h plasma glucose was 4.4 [95% CI 1.8-10.8 (P < 0.05)], after adjustments for covariates including fasting plasma glucose. The significance of the elevated hazard ratio in the fourth quartile of 1-h plasma glucose was maintained after adjustments for 2-h plasma glucose, insulinogenic index or disposition index, whereas the elevation of the hazard ratio in the fourth quartile of 2-h plasma glucose was diminished and was no longer significant after adjustments for 1-h plasma glucose.

CONCLUSIONS

One-hour plasma glucose had a greater association with the future development of Type 2 diabetes than did 2-h plasma glucose, independently of oral glucose tolerance test-derived indices of insulin action in a Japanese population.

Abstract 123: Adenoviral RhoA Regulation of Dynamin-related Protein 1 and Cardiac Mitochondrial Fission

G protein coupled receptors can signal downstream through various pathways, including activation of the small G protein RhoA. In cardiomyocytes, RhoA signaling is protective against ischemia/reperfusion injury. We have previously shown that this is mediated through downstream activation of Protein Kinase D (PKD), increased phosphorylation of cofilin, and diminished translocation of pro-apoptotic proteins to the mitochondria (Xiang et al, Sci. Signaling 2013). Mitophagy, a process that removes damaged mitochondria and limits mitochondrial death signaling, has also been suggested to be a cardioprotective response to oxidative stress. A step considered to be preliminary to clearance of damaged mitochondria via mitophagy is mitochondrial fission, and we hypothesized that RhoA signaling increases mitochondrial fission in cardiomyocytes. Constitutively active RhoA expressed in neonatal rat ventricular myocytes (NRVMs) was found to accumulate at the mitochondria. This was associated with an increase in small, fragmented mitochondria as observed by fluorescent confocal microscopy and electron microscopy, indicative of increased mitochondrial fission. The main protein involved in mitochondrial fission, dynamin-related protein 1 (Drp1), translocates from the cytosol to the mitochondria when activated. We used a tagged adenoviral Drp1 construct to determine whether expression of active RhoA changes Drp1 levels at the mitochondria. Mitochondrial Drp1 increased within 12 hours of adenoviral expression of active RhoA. Adenoviral RhoA expression also increased phosphorylation of Drp1 at serine-616 in NRVMs. In summary, we show that in cardiomyocytes, RhoA associates with mitochondria, can increase Drp1 phosphorylation and Drp1 mitochondrial localization, and can induce mitochondrial fission. The relationship between these mitochondrial signaling events and the protein kinases that are involved are currently under investigation. We suggest that G protein coupled receptors that stimulate RhoA can induce Drp1 accumulation and mitochondrial fission, which contributes to their cardioprotective effect.

FBXO10 deficiency and BTK activation upregulate BCL2 expression in mantle cell lymphoma

Targeting Bruton tyrosine kinase (BTK) by ibrutinib is an effective treatment for patients with relapsed/refractory mantle cell lymphoma (MCL). However, both primary and acquired resistance to ibrutinib have developed in a significant number of these patients. A combinatory strategy targeting multiple oncogenic pathways is critical to enhance the efficacy of ibrutinib. Here, we focus on the BCL2 anti-apoptotic pathway. In a tissue microarray of 62 MCL samples, BCL2 expression positively correlated with BTK expression. Increased levels of BCL2 were shown to be due to a defect in protein degradation because of no or little expression of the E3 ubiquitin ligase FBXO10, as well as transcriptional upregulation through BTK-mediated canonical nuclear factor-κB activation. RNA-seq analysis confirmed that a set of anti-apoptotic genes (for example, BCL2, BCL-XL and DAD1) was downregulated by BTK short hairpin RNA. The downregulated genes also included those that are critical for B-cell growth and proliferation, such as BCL6, MYC, PIK3CA and BAFF-R. Targeting BCL2 by the specific inhibitor ABT-199 synergized with ibrutinib in inhibiting growth of both ibrutinib-sensitive and -resistant cancer cells in vitro and in vivo. These results suggest co-targeting of BTK and BCL2 as a new therapeutic strategy in MCL, especially for patients with primary resistance to ibrutinib.

HK2/hexokinase-II integrates glycolysis and autophagy to confer cellular protection

Hexokinases (HKs) catalyze the first step of glucose metabolism, phosphorylating glucose to glucose 6-phosphate (G6P). HK2/hexokinase-II is a predominant isoform in insulin-sensitive tissues such as heart, skeletal muscle, and adipose tissues and is also upregulated in many types of tumors associated with enhanced aerobic glycolysis (the Warburg effect). Accumulating evidence indicates that HK2 plays an important role not only in glycolysis but also in cell survival. Although there is increasing recognition that cellular metabolism and cell survival are closely related, the molecular link between metabolism and autophagic pathways has not been fully elucidated. We recently discovered that HK2 facilitates autophagy in response to glucose deprivation (HK substrate deprivation) to protect cardiomyocytes, and suggest that HK2 functions as a molecular switch from glycolysis to autophagy to ensure cellular energy homeostasis under starvation conditions.