Expression of the c-Met oncogene by tumor cells predicts a favorable outcome in classical Hodgkin's lymphoma

Aberrant Expression of and Cell Death Induction by Engagement of the MHC-II Chaperone CD74 in Anaplastic Large Cell Lymphoma (ALCL)

Simple Summary

Anaplastic large cell lymphoma (ALCL) is a lymphoid malignancy considered to be derived from T cells. Currently, two types of systemic ALCL are distinguished: anaplastic lymphoma kinase (ALK)-positive and ALK-negative ALCL. Although ALK⁺ and ALK⁻ ALCL differ at the genomic and molecular levels, various key biological and molecular features are highly similar between both entities. We have developed the concept that both ALCL entities share a common principle of pathogenesis. In support of this concept, we here describe a common deregulation of CD74, which is usually not expressed in T cells, in ALCL. Ligation of CD74 induces cell death of ALCL cells in various conditions, and an anti-CD74-directed antibody-drug conjugate efficiently kills ALCL cell lines. Furthermore, we reveal expression of the proto-oncogene and known CD74 interaction partner MET in a fraction of ALCL cases. These data give insights into ALCL pathogenesis and might help to develop new treatment strategies for ALCL.

Abstract

In 50–60% of cases, systemic anaplastic large cell lymphoma (ALCL) is characterized by the t(2;5)(p23;q35) or one of its variants, considered to be causative for anaplastic lymphoma kinase (ALK)-positive (ALK⁺) ALCL. Key pathogenic events in ALK-negative (ALK⁻) ALCL are less well defined. We have previously shown that deregulation of oncogenic genes surrounding the chromosomal breakpoints on 2p and 5q is a unifying feature of both ALK⁺ and ALK⁻ ALCL and predisposes for occurrence of t(2;5). Here, we report that the invariant chain of the MHC-II complex CD74 or li, which is encoded on 5q32, can act as signaling molecule, and whose expression in lymphoid cells is usually restricted to B cells, is aberrantly expressed in T cell-derived ALCL. Accordingly, ALCL shows an altered DNA methylation pattern of the CD74 locus compared to benign T cells. Functionally, CD74 ligation induces cell death of ALCL cells. Furthermore, CD74 engagement enhances the cytotoxic effects of conventional chemotherapeutics in ALCL cell lines, as well as the action of the ALK-inhibitor crizotinib in ALK⁺ ALCL or of CD95 death-receptor signaling in ALK⁻ ALCL. Additionally, a subset of ALCL cases expresses the proto-oncogene MET, which can form signaling complexes together with CD74. Finally, we demonstrate that the CD74-targeting antibody-drug conjugate STRO-001 efficiently and specifically kills CD74-positive ALCL cell lines in vitro. Taken together, these findings enabled us to demonstrate aberrant CD74-expression in ALCL cells, which might serve as tool for the development of new treatment strategies for this lymphoma entity.

Immune Microenvironment Features and Dynamics in Hodgkin Lymphoma

Simple Summary

As happens in all neoplasms, the many reciprocal interactions taking place between neoplastic cells and the other reactive cells impact the course of the disease. Hodgkin Lymphoma is an haematologic malignancy where most of the pathological tissue is indeed composed by reactive cells and few neoplastic cells. Consequently, it represents an interesting subject for the description of the neoplastic and non-neoplastic cells interaction. In this review we report and discuss the more recent findings of microenvironmental studies about this disease.

Abstract

Classical Hodgkin’s lymphoma (cHL) accounts for 10% of all lymphoma diagnosis. The peculiar feature of the disease is the presence of large multinucleated Reed–Sternberg and mononuclear Hodgkin cells interspersed with a reactive microenvironment (ME). Due to the production of a large number of cytokines, Hodgkin cells (HCs) and Hodgkin Reed–Sternberg cells (HRSCs) attract and favour the expansion of different immune cell populations, modifying their functional status in order to receive prosurvival stimuli and to turn off the antitumour immune response. To this purpose HRSCs shape a biological niche by organizing the spatial distribution of cells in the ME. This review will highlight the contribution of the ME in the pathogenesis and prognosis of cHL and its role as a possible therapeutic target.

Autocrine HGF/c-Met signaling pathway confers aggressiveness in lymph node adult T-cell leukemia/lymphoma

Adult T-cell leukemia/lymphoma (ATL) is an aggressive T-cell neoplasm. While ATL cells in peripheral blood (PB-ATL) are sensitive to anti-CC chemokine receptor 4 treatment, non-PB-ATLs, including lymph node ATLs (LN-ATLs), are more aggressive and resistant. We examined characteristic cytokines and growth factors that allow non-PB-ATLs to proliferate and invade compared with PB-ATLs. Protein array analysis revealed hepatocyte growth factor (HGF) and C-C motif chemokine 2 (CCL2) were significantly upregulated in non-PB-ATLs compared with PB-ATLs. The HGF membrane receptor, c-Met, was expressed in PB-ATL and non-PB-ATL cell lines, but CCR2, a CCL2 receptor, was not. Immunohistochemical analysis in clinical ATLs revealed high HGF expression in LNs, pharynx, bone marrow, and tonsils. The HGF/c-Met signaling pathway was active downstream in non-PB-ATLs. Downregulation of HGF/c-Met by siRNA or chemical inhibitors decreased in vitro and in vivo proliferation and invasion by non-PB-ATLs. Treatment with bromodomain and extra-terminal motif inhibitor suppressed HGF expression and decreased levels of histone H3 lysine 27 acetylation (H3K27Ac) and bromodomain-containing protein 4 (BRD4) binding promoter and enhancer regions, suppressing non-PB-ATL cellular growth. Our data indicate H3K27Ac/BRD4 epigenetics regulates the HGF/c-MET pathway in ATLs; targeting this pathway may improve treatment of aggressive non-PB-ATLs.

Hepatocyte Growth Factor: A Microenvironmental Resource for Leukemic Cell Growth

Chronic lymphocytic leukemia (CLL) is characterized by the progressive expansion of B lymphocytes CD5+/CD23+ in peripheral blood, lymph-nodes, and bone marrow. The pivotal role played by the microenvironment in disease pathogenesis has become increasingly clear. We demonstrated that bone marrow stromal cells and trabecular bone cells sustain survival of leukemic B cells through the production of hepatocyte growth factor (HGF). Indeed the trans-membrane kinase receptor for HGF, c-MET, is expressed on CLL cells and STAT3 TYR⁷⁰⁵ or AKT phosphorylation is induced after HGF/c-MET interaction. We have further observed that c-MET is also highly expressed in a peculiar type of cells of the CLL-microenvironment showing nurturing features for the leukemic clone (nurse-like cells: NLCs). Since HGF treatment drives monocytes toward the M2 phenotype and NLCs exhibit features of tumor associated macrophages of type 2 we suggested that HGF, released either by cells of the microenvironment or leukemic cells, exerts a double effect: (i) enhances CLL cells survival and (ii) drives differentiation of monocytes-macrophages to an oriented immune suppressive phenotype. We here discuss how paracrine, but also autocrine production of HGF by malignant cells, may favor leukemic clone expansion and resistance to conventional drug treatments in CLL, as well as in other hematological malignancies. Novel therapeutic approaches aimed to block HGF/c-MET interactions are further proposed.

The Microenvironment in Epstein-Barr Virus-Associated Malignancies

The Epstein–Barr virus (EBV) can cause a wide variety of cancers upon infection of different cell types and induces a highly variable composition of the tumor microenvironment (TME). This TME consists of both innate and adaptive immune cells and is not merely an aspecific reaction to the tumor cells. In fact, latent EBV-infected tumor cells utilize several specific mechanisms to form and shape the TME to their own benefit. These mechanisms have been studied largely in the context of EBV+ Hodgkin lymphoma, undifferentiated nasopharyngeal carcinoma, and EBV+ gastric cancer. This review describes the composition, immune escape mechanisms, and tumor cell promoting properties of the TME in these three malignancies. Mechanisms of susceptibility which regularly involve genes related to immune system function are also discussed, as only a small proportion of EBV-infected individuals develops an EBV-associated malignancy.

miR-24-3p Is Overexpressed in Hodgkin Lymphoma and Protects Hodgkin and Reed-Sternberg Cells from Apoptosis

miRNAs play important roles in biological processes, such as proliferation, metabolism, differentiation, and apoptosis, whereas altered expression levels contribute to diseases, such as cancers. We identified miRNAs with aberrant expression in Hodgkin lymphoma (HL) and investigated their role in pathogenesis. Small RNA sequencing revealed 84 significantly differentially expressed miRNAs in HL cell lines as compared to germinal center B cells. Three up-regulated miRNAs-miR-23a-3p, miR-24-3p, and miR-27a-3p-were derived from one primary miRNA transcript. Loss-of-function analyses for these miRNAs and their seed family members resulted in decreased growth on miR-24-3p inhibition in three HL cell lines and of miR-27a/b-3p inhibition in one HL cell line. Apoptosis analysis indicated that the effect of miR-24-3p on cell growth is at least in part caused by an increase of apoptotic cells. Argonaute 2 immunoprecipitation revealed 1142 genes consistently targeted by miRNAs in at least three of four HL cell lines. Furthermore, 52 of the 1142 genes were predicted targets of miR-24-3p. Functional annotation analysis revealed a function related to cell growth, cell death, and/or apoptosis for 15 of the 52 genes. Western blotting of the top five genes showed increased protein levels on miR-24-3p inhibition for CDKN1B/P27^kip1 and MYC. In summary, we showed that miR-24-3p is up-regulated in HL and its inhibition impairs cell growth possibly via targeting CDKN1B/P27^kip1 and MYC.

Reverse the Resistance to PARP Inhibitors

One of the DNA repair machineries is activated by Poly (ADP-ribose) Polymerase (PARP) enzyme. Particularly, this enzyme is involved in repair of damages to single-strand DNA, thus decreasing the chances of generating double-strand breaks in the genome. Therefore, the concept to block PARP enzymes by PARP inhibitor (PARPi) was appreciated in cancer treatment. PARPi has been designed and tested for many years and became a potential supplement for the conventional chemotherapy. However, increasing evidence indicates the appearance of the resistance to this treatment. Specifically, cancer cells may acquire new mutations or events that overcome the positive effect of these drugs. This paper describes several molecular mechanisms of PARPi resistance which were reported most recently, and summarizes some strategies to reverse this type of drug resistance.

The role of HGF/c-MET signaling pathway in lymphoma

Inappropriate activation of c-mesenchymal-epithelial transition (MET), the receptor tyrosine kinase (RTK) for hepatocyte growth factor (HGF), has been implicated in tumorigenesis and represented a promising therapeutic target for developing anticancer agents. In contrast to other solid tumors, there are limited data describing the functional role of HGF/c-MET signaling pathway in lymphoma. In the current review, we summarize recent findings about the expression, cellular mechanisms/functions, and therapeutic application of HGF/c-MET in different types of lymphoma, especially B cell lymphoma, T and NK cell lymphoma, and Hodgkin lymphoma. We also discuss the existing problems and future directions about studying the HGF/c-MET pathway in lymphoma cells.

Suppressor of cytokine signaling 1 gene mutation status as a prognostic biomarker in classical Hodgkin lymphoma

Suppressor of cytokine signaling 1 (SOCS1) mutations are among the most frequent somatic mutations in classical Hodgkin lymphoma (cHL), yet their prognostic relevance in cHL is unexplored. Here, we performed laser-capture microdissection of Hodgkin/Reed-Sternberg (HRS) cells from tumor samples in a cohort of 105 cHL patients. Full-length SOCS1 gene sequencing showed mutations in 61% of all cases (n = 64/105). Affected DNA-motifs and mutation pattern suggest that many of these SOCS1 mutations are the result of aberrant somatic hypermutation and we confirmed expression of mutant alleles at the RNA level. Contingency analysis showed no significant differences of patient-characteristics with HRS-cells containing mutant vs. wild-type SOCS1. By predicted mutational consequence, mutations can be separated into those with non-truncating point mutations (‘minor’ n = 49/64 = 77%) and those with length alteration (‘major’; n = 15/64 = 23%). Subgroups did not differ in clinicopathological characteristics; however, patients with HRS-cells that contained SOCS1 major mutations suffered from early relapse and significantly shorter overall survival (P = 0.03). The SOCS1 major status retained prognostic significance in uni-(P = 0.016) and multivariate analyses (P = 0.005). Together, our data indicate that the SOCS1 mutation type qualifies as a single-gene prognostic biomarker in cHL.

c-MET expression in colorectal adenomas and primary carcinomas with its corresponding metastases

BACKGROUND

c-MET plays an important role in tumor proliferation, invasion and metastasis. In this study we examined the expression of c-MET in colorectal adenomas, primary adenocarcinomas and their corresponding lymph node, peritoneal and liver metastases. We correlated our findings with clinicopathological features.

METHODS

Twenty three cases of colorectal adenoma and 102 cases of primary colorectal carcinoma and their corresponding metastases (44 lymph nodes, 21 peritoneal deposits and 16 liver metastases) were studied to evaluate c-MET expression by immunohistochemistry. For comparison, 12 sections of adjacent healthy colorectal mucosa were examined.

RESULTS

Statistically significant differences were present among normal tissues, colorectal adenomas and primary colorectal carcinomas (P=0.011). Normal tissues showed a negative or weak reaction in 66.67% and 33.33% of cases respectively. Expression of c-MET was positive in 47.8% of adenomas. A significant positive association was identified between c-MET high expression and degree of dysplasia (P=0.024). c-MET was highly expressed in 66.7% of primary colorectal carcinoma. Significant positive correlations were detected between c-MET expression and TNM stage (P=0.036), lymph node metastasis (LNM), peritoneal deposits and liver metastasis (P=0.038, P=0.094 and P=0.045, respectively). c-MET expression in metastatic tissues was significantly higher than that of the primary tumor.

CONCLUSIONS

c-MET expression is gradually up-regulated in the development and progression of colorectal cancer (CRC) from normal epithelium to adenoma to colorectal carcinoma to metastases.

Insulin-like growth factor-1 receptor is associated with better prognosis in classical Hodgkin's lymphoma: Correlation with MET expression

The purpose of this study was to examine the prognostic significance of insulin-like growth factor-1 receptor (IGF-1R) expression alone and in relation to the expression of the MET- receptor and the MET-homologous receptor RON, in classical Hodgkin's lymphoma (cHL). Tumour samples from patients with cHL (n = 202; median age 37.5 years) were analysed retrospectively for IGF-R1, MET or RON expression by immunohistochemistry using tissue microarrays. The median follow-up time was 3.7 years (range, 0.1-20 years). Twenty-nine patients (14.3%) expressed IGF-1R protein in Hodgkin/Reed-Sternberg (HRS) cells, which was associated with a better overall survival (OS) (P = 0.036). IGF-1R expression was closely associated with MET receptor expression and low level of lactate dehydrogenase. In patients with cHL receiving doxorubicin, bleomycin, vinblastine and dacarbazine, those expressing IGF-1R showed a trend towards better OS and event-free survival than IGF-1R-negative patients (P = 0.129 and P = 0.115 respectively), but statistical significance was not reached. This study suggests that IGF-1R expression could be associated with better clinical outcome in cHL but is significantly associated with the expression of MET receptor.

New Immunohistochemistry for B-Cell Lymphoma and Hodgkin Lymphoma

Context

B-cell non-Hodgkin lymphoma is a heterogeneous group of lymphoproliferative malignancies with different clinical behaviors and treatments. It is important to differentiate individual B-cell lymphoma to apply the best treatment and management. Morphology and immunohistochemistry are the primary tools used for diagnosing lymphoma. There is a characteristic pattern of expression with immunohistochemical antibodies in most well-defined B-cell lymphomas. Some cases of B-cell lymphoma, however, show unusual morphologic and immunophenotypic features. The new and sometimes more specific antibodies have been developed recently, which may further define those lymphomas. Only with use of the antibodies over time does their true nature and specificity become evident.

Objectives

To present new antibodies for B-cell lymphoma that enhance the probability for diagnosis or can act as alternate markers in unusual cases, in which a B-cell lymphoma does not present with characteristic immunohistochemical staining, and to present prognostic markers that allow for better management of patients with specific B-cell lymphomas.

Data Sources

Data were obtained from literature review and figures from slides in personal practice.

Conclusions

The immunohistochemical antibodies presented in this article increase our ability to understand, diagnosis, and manage patients with B-cell lymphoma.

MET expression is associated with disease-specific survival in breast cancer patients in the neoadjuvant setting

MET and RON receptor tyrosine kinases play an important role in tumor progression. The aim of this study was to determine the predictive or prognostic impact of MET and RON in breast cancer patients treated with neoadjuvant chemotherapy (NAC). Immunohistochemical analyses were performed to retrospectively examine the predictive or prognostic impact of MET and RON expression in 129 breast cancer patients treated with NAC followed by definitive surgical resection. MET-positive tumors were detected in 89 patients (68.9%) and RON-positive tumors in 94 patients (72.9%). Survival analysis showed that MET expression was correlated with longer disease-specific survival (DSS; P=0.016), whereas RON expression was not associated with survival rates. MET expression was a significant factor for DSS in the non-pCR group in subgroup analysis (P=0.024) and a marginal significant independent prognostic factor for DSS in multivariate analysis. The MET-positive group had higher pCR than the MET-negative group but the difference was not statistically significant (P=0.266). MET expression is a prognostic factor for DSS in breast cancer patients receiving NAC and may provide additional prognostic information in patients not achieving a pCR.

Insulin-like growth factor 1 receptor is a prognostic factor in classical Hodgkin lymphoma

The interaction between the tumor cells in classical Hodgkin lymphoma (cHL) and the microenvironment includes aberrant activity of receptor tyrosine kinases. In this study we evaluated the expression, functionality and prognostic significance of Insulin-like growth factor-1 receptor (IGF-1R) in cHL. IGF-1R was overexpressed in 55% (44/80) of cHL patients. Phosphorylated IGF-1R was detectable in a minority of the IGF-1R positive tumor cells. The overall survival (OS, 98%) and 5-year progression-free survival (PFS, 93%) was significantly higher in IGF-1R positive cHL patients compared to IGF-1R negative patients (OS 83%, p = .029 and PFS 77%, p = .047, respectively). Three cHL cell lines showed expression of IGF-1R, with strong staining especially in the mitotic cells and expression of IGF-1. IGF-1 treatment had a prominent effect on the cell growth of L428 and L1236 cells and resulted in an increased phosphorylation of IGF1R, Akt and ERK. Inhibition of IGF-1R with cyclolignan picropodophyllin (PPP) decreased cell growth and induced a G2/M cell cycle arrest in all three cell lines. Moreover, a decrease in pCcd2 and an increase in CyclinB1 levels were observed which is consistent with the G2/M cell cycle arrest. In conclusion, IGF-1R expression in HRS cells predicts a favorable outcome, despite the oncogenic effect of IGF-1R in cHL cell lines.

MET and MST1R as prognostic factors for classical Hodgkin's lymphoma

MST1R (RON) and MET are receptor tyrosine kinase gene family members that form a noncovalent complex on the cell surface, a critical step in tumor progression. A recent study suggested a prognostic role of MET expression in Hodgkin/Reed-Sternberg (HRS) cells in classical Hodgkin's lymphoma (cHL). The purpose of this study was to examine the prognostic significance of MET and MST1R expression in cHL. The prognostic impact of MET and MST1R was examined in 100 patients with cHL (median age: 32 years) by immunohistochemistry and mRNA in situ hybridization. The median follow-up time was 95 months (interquartile range: 42-126 months). MET or MST1R protein expression was associated with high MET or MST1R mRNA expression, respectively. Thirty-eight patients (38%) expressed MET protein in HRS cell, which was associated with better overall survival (P=0.004). Twenty-six patients (26%) expressed MST1R protein, which was associated with better overall survival (P=0.022) and event-free survival (P=0.021). Multivariate analysis identified MET protein as an independent prognostic factor for overall survival and MST1R protein as an independent prognostic factor for event-free survival. Subgroup analysis according to Ann Arbor stage showed that expressions of MET and MST1R protein have prognostic impact in the advanced stage only. In particular, coexpression of MST1R and MET protein was associated with a better survival outcome than MET or MST1R expression alone or no expression. This study suggests that MET and MST1R are independent prognostic factors in classical cHL, and may allow the identification of a subgroup of cHL patients who require more intensive therapy.

The microenvironment in classical Hodgkin lymphoma: an actively shaped and essential tumor component

Classical Hodgkin lymphoma (cHL) is characterized by a minority of tumor cells derived from germinal center B-cells and a vast majority of non-malignant reactive cells. The tumor cells show a loss of B-cell phenotype including lack of the B-cell receptor, which makes the tumor cells vulnerable to apoptosis. To overcome this threat, tumor cells and their precursors depend on anti-apoptotic and growth stimulating factors that are obtained via triggering of multiple membrane receptors. In addition, tumor cells shape the environment by producing a wide variety of chemokines and cytokines. These factors alter the composition of the microenvironment and modulate the nature and effectiveness of the infiltrating cells. The attracted cells enhance the pro-survival and growth stimulating signals for the tumor cells. To escape from an effective anti-tumor response tumor cells avoid recognition by T and NK cells, by downregulation of HLA molecules and modulating NK and T-cell receptors. In addition, the tumor cells produce immune suppressive cytokines that inhibit cytotoxic responses. In this review the relevance of the microenvironment in the pathogenesis of cHL will be discussed.

CD163 and c-Met expression in the lymph node and the correlations between elevated levels of serum free light chain and the different clinicopathological parameters of advanced classical Hodgkin's lymphoma

BACKGROUND

Advances in the understanding of Hodgkin's lymphoma (HL) show various functions of infiltrating immune cells and cytokines in relation to clinical outcomes. The expression of CD163 and c-Met has been suggested to have a role in lymphoid malignancy. Thus, we evaluated the expressions of CD163, c-Met, and serum free light chain (sFLC) in relation to the clinicopathological features of patients with advanced classical HL (cHL).

METHODS

We assessed the expression of CD163 and c-Met in 34 patients with cHL through immunohistochemistry on the lymph node biopsy sections and the levels of pretreatment sFLC were estimated using ELISA.

RESULTS

High CD163 expression correlated with increased age, B symptoms, International Prognostic Score (IPS) ≥3, mixed cellularity subtype, and low response to treatment. Further, high c-Met expression correlated with increased age at diagnosis, leukocytosis, B symptoms, and lower chance to achieve complete remission. The sFLC levels correlated with increased age at diagnosis, lymphopenia, IPS ≥3, B symptoms, and lower complete remission rates.

CONCLUSION

In advanced cHL, increased expression of CD163 and c-Met showed a significant association with adverse prognostic parameters and poor response to treatment. Pretreatment high sFLC level also correlated with poor risk factors, suggesting its use as a candidate prognostic marker. A comprehensive approach for prognostic markers might represent a step towards developing a tailored therapeutic approach for HL.