Prostate cancer (PCa) nodal staging does not account for lymph node (LN) tumor burden. The LN anatomical compartment involved with the tumor or the quantified extent of extranodal extension (ENE) ...have not yet been studied in relation to biochemical recurrence-free survival (BRFS).
Histopathological slides of 66 pN1 PCa patients who underwent extended pelvic lymph node dissection were reviewed. We recorded metrics to quantify LN tumor burden. We also characterized the LN anatomical compartments involved and quantified the extent of ENE.
The median follow-up time was 38 months. The median number of total LNs obtained per patient was 30 (IQR 23-37). In the risk-adjusted cox regression model, the following variables were associated with BRFS: mean size of the largest LN deposit per patient (log2: adjusted hazard ratio (aHR) = 1.91,
< 0.001), the mean total span of all LN deposits per patient (2.07,
< 0.001), and the mean percent surface area of the LN involved with the tumor (1.58,
< 0.001). There was no significant BRFS association for the LN anatomical compartment or the quantified extent of ENE.
LN tumor burden is associated with BRFS. The LN anatomical compartments and the quantified extent of ENE did not show significant association with BRFS.
Hypermethylation of the promoter region of tumor-related genes (TRGs) has been shown to silence gene expression during melanoma progression, whereas microRNA-29(miR-29) has been found to downregulate ...DNA methyltransferases DNMT3A and DNMT3B which were shown as essential to the methylation of TRGs. We hypothesized that the expression level of miR-29 is associated to TRG methylation status and may have prognostic utility in melanoma. AJCC stage I-IV cutaneous melanoma paraffin-embedded archival tissue (PEAT) specimens (n=149) were assessed. Expression of miR-29 isoforms a, b, and c were analyzed by reverse-transcription quantitative real-time polymerase chain reaction(RT-qPCR). Expression of DNMT3A and DNMT3B was assessed by immunohistochemistry(IHC) on defined clinically annotated tissue microarrays (TMA) of AJCC stage III melanoma lymph node metastases. Promoter region CpG island methylation status of RASSF1A, TFPI-2, RAR-β, SOCS, GATA4 and genomic repeat sequence MINT17 and MINT31 were previously evaluated in melanoma tissues. Only miR-29c isoform expression was correlated to advancing AJCC stages in melanoma. miR-29c expression was significantly downregulated in AJCC stage IV melanoma tumors compared to primary melanomas. Hypermethylation status of TRGs and non-coding MINT loci in different stages of melanoma showed an inverse association with miR-29c expression. Overall, an increase in miR-29c expression inversely correlated to both DNMT3A and DNMT3B protein expression in melanomas. Expression of DNMT3B and miR-29c were significantly (p=0.004 and p=0.002, respectively) associated with overall survival(OS) in AJCC stage III melanoma patients by multivariate analysis. The studies demonstrated that both miR-29c and DNMT3B have significant roles in melanoma progression, and may be useful epigenetic biomarkers for disease outcome.
Brain metastasis (BM) frequently occurs in patients with cutaneous melanoma, lung, and breast cancer; although, BM rarely arises from cancers of the gastrointestinal tract (GIT). The reported ...incidence of GIT cancer BM is less than 4%. In the last few years, effective systemic therapy has prolonged the survival of GIT patients and consequently, the incidence of developing BM is rising. Therefore, the epidemiology and biology of BM arising from GIT cancer requires a more comprehensive understanding. In spite of the development of new therapeutic agents for patients with metastatic GIT cancers, survival for patients with BM still remains poor, with a median survival after diagnosis of less than 4 months. Limited evidence suggests that early detection of isolated intra-cranial lesions will enable surgical resection plus systemic and/or radiation therapy, which may lead to an increase in overall survival. Novel diagnostic methods such as blood-based biomarker biopsies may play a crucial role in the early detection of BM. Circulating tumor cells and circulating cell-free nucleic acids are known to serve as blood biomarkers for early detection and treatment response monitoring of multiple cancers. Blood biopsy may improve early diagnosis and treatment monitoring of GIT cancers BM, thus prolonging patients’ survivals.
Patients with triple-negative breast cancer (TNBC) have a high incidence of early relapse and metastasis; however, the molecular basis for recurrence in these individuals remains poorly understood. ...Here, we demonstrate that RASAL2, which encodes a RAS-GTPase-activating protein (RAS-GAP), is a functional target of anti-invasive microRNA-203 and is overexpressed in a subset of triple-negative or estrogen receptor-negative (ER-negative) breast tumors. As opposed to luminal B ER-positive breast cancers, in which RASAL2 has been shown to act as a RAS-GAP tumor suppressor, we found that RASAL2 is oncogenic in TNBC and drives mesenchymal invasion and metastasis. Moreover, high RASAL2 expression was predictive of poor disease outcomes in patients with TNBC. RASAL2 acted independently of its RAS-GAP catalytic activity in TNBC; however, RASAL2 promoted small GTPase RAC1 signaling, which promotes mesenchymal invasion, through binding and antagonizing the RAC1-GAP protein ARHGAP24. Together, these results indicate that activation of a RASAL2/ARHGAP24/RAC1 module contributes to TNBC tumorigenesis and identify a context-dependent role of RASAL2 in breast cancer.
Purpose: RUNX3 is a known tumor suppressor gene in several carcinomas. Aberration in RUNX3 expression has not been described for cutaneous
melanoma. Therefore, we assessed the expression of RUNX3 in ...cutaneous melanoma and its regulatory mechanisms relative to tumor
progression.
Experimental Design: The expression of RUNX3 mRNA and miR-532-5p (microRNA) was assessed in melanoma lines and in primary and metastatic melanoma
tumors.
Results: RUNX3 mRNA expression was down-regulated in 11 of 11 (100%) metastatic melanoma lines relative to normal melanocytes ( P < 0.001). Among 123 primary and metastatic melanoma tumors and 12 normal skin samples, RUNX3 expression was significantly
down-regulated in primary melanomas ( n = 82; P = 0.02) and in melanoma metastasis ( n = 41; P < 0.0001) versus normal skin ( n = 12). This suggested that RUNX3 down-regulation may play a role in the development and progression of melanoma. RUNX3 promoter
region hypermethylation was assessed as a possible regulator of RUNX3 expression using methylation-specific PCR. Assessment
of RUNX3 promoter region methylation showed that only 5 of 17 (29%) melanoma lines, 2 of 52 (4%) primary melanomas, and 5
of 30 (17%) metastatic melanomas had hypermethylation of the promoter region. A microRNA (miR-532-5p) was identified as a
target of RUNX3 mRNA sequences. miR-532-5p expression was shown to be significantly up-regulated in melanoma lines and metastatic
melanoma tumors relative to normal melanocytes and primary melanomas, respectively. To investigate the relation between RUNX3
and miR-532-5p, anti–miR-532-5p was transfected into melanoma lines. Inhibition of miR-532-5p up-regulated both RUNX3 mRNA
and protein expression.
Conclusions: RUNX3 is down-regulated during melanoma progression and miR-532-5p is a regulatory factor of RUNX3 expression.
Aberrant methylation of CpG islands in promoter regions of tumor suppressor genes (TSG) has been demonstrated in epithelial origin tumors. However, the methylation profiling of tumor-related gene ...promoter regions in cutaneous melanoma tumors has not been reported. Seven known or candidate TSGs that are frequently hypermethylated in carcinomas were assessed by methylation-specific polymerase chain reaction (MSP) in 15 melanoma cell lines and 130 cutaneous melanoma tumors. Four TSGs were frequently hypermethylated in 86 metastatic tumor specimens: retinoic acid receptor-beta2 (RAR-beta2) (70%), RAS association domain family protein 1A (RASSF1A) (57%), and O6-methylguanine DNA methylatransferase (MGMT) (34%), and death-associated protein kinase (DAPK) (19%). Hypermethylation of MGMT, RASSF1A, and DAPK was significantly lower in primary melanomas (n=20) compared to metastatic melanomas. However, hypermethylation of RAR-beta2 was 70% in both primary and metastatic melanomas. Cell lines had hypermethylation profiles similar to those of metastatic melanomas. The analysis of these four markers of metastatic tumors demonstrated that 97% had > or =1 gene(s) and 59% had > or =2 genes hypermethylated. The methylation of genes was verified by bisulfite sequencing. The mRNA transcripts could be re-expressed in melanoma cell lines having hypermethylated genes following treatment with 5'-aza 2'-deoxycytidine (5Aza-dC). Analysis of melanoma patients' plasma (preoperative blood; n=31) demonstrated circulating hypermethylated MGMT, RAR-beta2, and RASSF1A DNA for at least one of the markers in 29% of the patients. Our findings indicate that the incidence of TSG hypermethylation increases during tumor progression. Methylation of TSG may play a significant role in cutaneous melanoma progression.
Genomic instability can be a hallmark of both human genetic disease and cancer. We identify a deleterious UBQLN4 mutation in families with an autosomal recessive syndrome reminiscent of genome ...instability disorders. UBQLN4 deficiency leads to increased sensitivity to genotoxic stress and delayed DNA double-strand break (DSB) repair. The proteasomal shuttle factor UBQLN4 is phosphorylated by ATM and interacts with ubiquitylated MRE11 to mediate early steps of homologous recombination-mediated DSB repair (HRR). Loss of UBQLN4 leads to chromatin retention of MRE11, promoting non-physiological HRR activity in vitro and in vivo. Conversely, UBQLN4 overexpression represses HRR and favors non-homologous end joining. Moreover, we find UBQLN4 overexpressed in aggressive tumors. In line with an HRR defect in these tumors, UBQLN4 overexpression is associated with PARP1 inhibitor sensitivity. UBQLN4 therefore curtails HRR activity through removal of MRE11 from damaged chromatin and thus offers a therapeutic window for PARP1 inhibitor treatment in UBQLN4-overexpressing tumors.
Display omitted
•Homozygous UBQLN4 germline mutations lead to a genome instability syndrome•UBQLN4 removes ubiquitylated MRE11 from damaged chromatin to curtail DSB resection•UBQLN4 overexpression represses HRR and promotes the use of NHEJ for DSB repair•UBQLN4 overexpression in tumors promotes PARP1 inhibitor sensitivity
Control of MRE11 association with chromatin by UBQLN4 during double-strand break repair influences repair pathway choice and can be dysregulated in tumorigenesis.
Melanoma has the highest propensity to metastasize to the brain compared to other cancers, as brain metastases are found frequently high in patients who have prolonged survival with visceral ...metastasis. Once disseminated in the brain, melanoma cells communicate with brain resident cells that include astrocytes and microglia. Microglia cells are the resident macrophages of the brain and are the main immunological cells in the CNS involved in neuroinflammation. Data on the interactions between brain metastatic melanoma cells and microglia and on the role of microglia‐mediated neuroinflammation in facilitating melanoma brain metastasis are lacking. To elucidate the role of microglia in melanoma brain metastasis progression, we examined the bidirectional interactions between microglia and melanoma cells in the tumor microenvironment. We identified the molecular and functional modifications occurring in brain‐metastasizing melanoma cells and microglia cells after the treatment of each cell type with supernatants of the counter cell type. Both cells induced alteration in gene expression programs, cell signaling, and cytokine secretion in the counter cell type. Moreover, melanoma cells exerted significant morphological changes on microglia cells, enhanced proliferation, induced matrix metalloproteinase‐2 (MMP‐2) activation, and cell migration. Microglia cells induced phenotypic changes in melanoma cells increasing their malignant phenotype: increased melanoma proliferation, MMP‐2 activity, cell migration, brain endothelial penetration, and tumor cells ability to grow as spheroids in 3D cultures. Our work provides a novel insight into the bidirectional interactions between melanoma and micoglia cells, suggesting the contribution of microglia to melanoma brain metastasis formation.
What's new?
Activated microglia are found in metastatic brain lesions of several tumors. However, their role in tumorigenesis and metastasis remains controversial. Here, the authors found that brain‐metastasizing melanoma cells and microglia cells induced reciprocal alteration in their gene expression pattern, cell signaling, and cytokine secretion. Moreover, melanoma cells exerted significant morphological changes on microglia cells, enhanced proliferation, induced matrix metalloproteinase‐2 activation and cell migration. Microglia cells induced phenotypic changes in melanoma cells increasing their malignant phenotype. The work provides a novel insight into the bidirectional interactions between melanoma and microglia cells, suggesting the contribution of microglia to melanoma brain metastasis formation.
Despite showing promise against
-mutant breast cancers in preclinical studies, PI3K/AKT pathway inhibitors demonstrate limited clinical efficacy as monotherapy. Here, we found that histone H3K27me3 ...demethylase KDM6B-targeted
expression provides a protective mechanism for PI3K/AKT inhibitor-induced apoptosis in breast cancer cells. We found that overexpression of
and
in luminal breast cancer are positively associated with poorer disease outcomes. Mechanistically, KDM6B promotes
expression by antagonizing EZH2-mediated repression, and pharmacologic inhibition of KDM6B augments apoptotic response to PI3K/AKT inhibitor treatment. Moreover, the
expression is upregulated upon acquired resistance to the PI3K inhibitor GDC-0941, which is associated with an epigenetic switch from H3K27me3 to H3K27Ac at the
gene promoter. Intriguingly, GDC-0941-resistant breast cancer cells remained sensitive to KDM6B or IGFBP5 inhibition, indicating the dependency on the KDM6B-IGFBP5 axis to confer the survival advantage in GDC-0941-resistant cells. Our study reveals an epigenetic mechanism associated with resistance to targeted therapy and demonstrates that therapeutic targeting of KDM6B-mediated IGFBP5 expression may provide a useful approach to mitigate both intrinsic and acquired resistance to the PI3K inhibitor in breast cancer.
.
PDF
