Peutz-Jeghers syndrome associated with primary malignant melanoma of the rectum

Primary digestive melanoma in association with tubular adenoma: a case report illustrating the distinction from metastatic colonic melanoma

We report here an exceptional pattern of atypical lentiginous melanocytic proliferation within an adenoma, leading to focal lamina propria infiltration and pulmonary metastasis, which was considered as primary colonic mucosal melanoma (MM) in a Caucasian patient. Such case illustrates the diagnosis criteria required to differentiate primary MM from colonic metastasis of melanoma, including the absence of past history of other primary melanoma, a unique colonic and abdominal lesion with predominant features of in situ lentiginous MM and a very focal and unique invasive area without other digestive tract or abdominal localization. This tumor displayed a KIT exon 11 mutation leading to a unique combination of p.I571M and p.D572G deleterious amino acid changes. Such pattern also favors the diagnosis as KIT appears as a master oncogenic player in MM oncogenesis.

NUAK2: an emerging acral melanoma oncogene

Recent technological advances in cancer genomics make it possible to dissect complicated genomic aberrations of melanomas. In particular, several specific genomic aberrations including 11q13 amplification and KIT aberrations have been identified in acral melanomas. We recently identified NUAK2 at 1q32 as a promising oncogene in acral melanomas and reported its significant roles in tumorigenesis in melanoma cells using both in vitro and in vivo analyses. NUAK2 as a member of the AMPK family has several intriguing aspects both as an oncogene and as a tumor suppressor gene. Here we review genomic aberrations of melanomas focusing on acral melanomas to emphasize the possible roles of NUAK2 in tumorigenesis in general and suggest that NUAK2 has pivotal roles in acral melanomagenesis.

The differential diagnosis of familial lentiginosis syndromes

Cutaneous markers of systemic disease are vital for clinicians to recognize. This chapter outlines familial lentiginosis syndromes that include Peutz-Jeghers syndrome, Carney Complex, the PTEN hamartomatous syndromes, and LEOPARD/Noonan syndrome. The inheritance of these syndromes is autosomal dominant; they also share characteristic skin findings that offer a clue to their recognition and treatment. We will discuss the clinical presentation of these disorders, with a focus on the dermatological manifestations, and will provide an update on the molecular mechanisms involved. Recognition of cutaneous markers associated with these rare familial cancer syndromes provides the opportunity to pursue early surveillance for malignancies, as well as genetic counseling.

AMP kinase-related kinase NUAK2 affects tumor growth, migration, and clinical outcome of human melanoma

The identification of genes that participate in melanomagenesis should suggest strategies for developing therapeutic modalities. We used a public array comparative genomic hybridization (CGH) database and real-time quantitative PCR (qPCR) analyses to identify the AMP kinase (AMPK)-related kinase NUAK2 as a candidate gene for melanomagenesis, and we analyzed its functions in melanoma cells. Our analyses had identified a locus at 1q32 where genomic gain is strongly associated with tumor thickness, and we used real-time qPCR analyses and regression analyses to identify NUAK2 as a candidate gene at that locus. Associations of relapse-free survival and overall survival of 92 primary melanoma patients with NUAK2 expression measured using immunohistochemistry were investigated using Kaplan-Meier curves, log rank tests, and Cox regression models. Knockdown of NUAK2 induces senescence and reduces S-phase, decreases migration, and down-regulates expression of mammalian target of rapamycin (mTOR). In vivo analysis demonstrated that knockdown of NUAK2 suppresses melanoma tumor growth in mice. Survival analysis showed that the risk of relapse is greater in acral melanoma patients with high levels of NUAK2 expression than in acral melanoma patients with low levels of NUAK2 expression (hazard ratio = 3.88; 95% confidence interval = 1.44-10.50; P = 0.0075). These data demonstrate that NUAK2 expression is significantly associated with the oncogenic features of melanoma cells and with the survival of acral melanoma patients. NUAK2 may provide a drug target to suppress melanoma progression. This study further supports the importance of NUAK2 in cancer development and tumor progression, while AMPK has antioncogenic properties.

Melanoma in the gastrointestinal tract

OBJECTIVE

This article focuses on the clinical, diagnostic, and therapeutic aspects of malignant melanoma metastases to the gastrointestinal (GI) tract. The subject of primary malignant melanoma arising from the GI tract is also discussed. Malignant melanoma is the most common tumor metastatic to the GI tract, and can present with fairly non-specific symptoms.

METHODS

Up to 60% of patients with melanoma are found to have metastases at autopsy. Frequent GI sites of invasion include the small bowel (50%), colon (31.3%), and anorectum (25%), seen in our institution over the past 9 yr. Malignant melanoma is a frequent source of metastases to the gastrointestinal (GI) tract.

RESULTS

Herein we report the case of a melanoma masquerading as a rectal polyp. We have also discovered 16 cases of melanoma metastases to the GI tract, at our institution, over the past 9 yr. The most frequent sites included small bowel (50%), colon (31.3%), and anorectum (25%).

CONCLUSION

Despite innocuous gastrointestinal symptoms, metastatic melanoma should be a diagnostic consideration in any patient with a history of melanoma.

Somatic mutation of the Peutz-Jeghers syndrome gene, LKB1/STK11, in malignant melanoma

Mutations in LKB1/STK11, a gene mapping to chromosome 19p13.3 and encoding a widely expressed serine/threonine kinase, were recently identified as the cause of Peutz-Jeghers syndrome. Despite the hamartomatous polyps and increased cancer risk associated with this syndrome, somatic alterations in LKB1/STK11 have not been identified in human tumours. Prompted by another feature of the syndrome, lentigines of the lips and oral mucosa, we evaluated the status of LKB1/STK11 expression, deletion, and mutation in cell lines and tumour samples from 35 patients with sporadic malignant melanoma. Two somatic mutations were identified, a nonsense mutation (Glu170Stop) causing exon skipping and intron retention, and a missense mutation (Asp194Tyr) affecting an invariant residue in the catalytic subunit of LKB1/STK11. Our data suggest that LKB1/STK11 may contribute to tumorigenesis in a small fraction of malignant melanomas.