PTEN immunohistochemical loss, a common event in endometrioid-type endometrial carcinoma and associated with local immune suppression in melanoma, was not associated with PD-L1 expression or lymphocyte/macrophage infiltration of the tumor.
Analysis of array-CGH data revealed that PTEN deficiency is coupled tightly with genomic amplification encompassing the NUAK2 locus, a finding strengthened by immunohistochemical evidence that phospho-Akt overexpression was correlated with NUAK2 expression in clinical specimens of acral melanoma.
Our findings corroborate that loss of heterozygosity on chromosome 10 is a frequent aberration in malignant melanomas and implicate PTEN as a tumour suppressor gene inactivated by somatic mutation in a fraction of these tumours.
Here, we show that concurrent loss of PTEN and activation of the Notch pathway is associated with poor response to the ERK inhibitor SCH772984, and that co-inhibition of Notch and ERK decreased viability in BRAF-V600Emelanomas.
PTEN deficiency and Braf activation, two common coincident genetic alterations found in primary cutaneous melanomas, were first introduced into human melanocytes previously immortalized by the SV40 large T antigen and telomerase.
Analysis of a melanoma tissue microarray showed loss of PTEN expression to predict for a lower overall survival, with a trend for even lower survival being seen when loss of fibronectin was included in the analysis.
Although deletions or inactivating mutations of the tumor suppressor gene PTEN (phosphatase and tensin homolog deleted on chromosome 10) are involved in the development of a variety of tumors including glioblastoma, melanoma, prostate cancer, breast cancer, endometrial cancers etc., the role of PTEN expression in human primary hepatocellular carcinoma (HCC) has not yet been clarified.
Taken together, our findings provide a strong rationale for testing combinations of panPI3K, PI3Kβ + IGF1R, and MAPK pathway inhibitors in PTEN(LOF)/BRAF(MUT) melanoma patients to achieve maximal response.
These results indicate that LOH of the PTEN region is one of the molecular alterations of an ovarian mature cystic teratoma and a KIT mutation is an additional promotional event associated with the oncogenesis of a melanoma arising from an ovarian mature cystic teratoma.
In contrast to melanomas in the general population, the frequency of BRAF mutations (11%, 7/61), NRAS mutations (21%, 13/62), and KIT mutations (21%, 6/28) in XP melanomas was lower than for PTEN.
Mutations in the PTEN/MMAC1 gene have been identified in several types of human cancers and cancer cell lines, including brain, endometrial, prostate, breast, thyroid, and melanoma.
Co-treatment of phenformin enhances the effect of anti-PD-1 antibody therapy on inhibiting tumor growth in the BRAF V600E/PTEN-null melanoma mouse model.
Collectively, these findings suggest that disruption of MMAC1/PTEN by allelic loss or mutation may contribute to the pathogenesis or neoplastic evolution in a large proportion of malignant melanomas.
The dCas9-VPR system increased PTEN expression in melanoma and TNBC cell lines, without transcriptional regulation at predicted off-target sgRNA binding sites.
These data support the notion that PTEN alterations occur in some metastatic melanomas, and that mutation of this gene plays a role in the progression of some forms of melanoma.