Update on lacrimal gland neoplasms: Molecular pathology of interest

MiR-29a-3p inhibits high-grade transformation and epithelial-mesenchymal transition of lacrimal gland adenoid cystic carcinoma by targeting Quaking

BACKGROUND

Lacrimal adenoid cystic carcinoma (LACC) is the most common orbital malignant epithelial neoplasm. LACC with high-grade transformation (LACC-HGT) has higher rates of recurrence, metastasis, and mortality than LACC without HGT. This study investigated the effects of microRNA-29a-3p (miR-29a-3p) in the pathogenesis of LACC-HGT.

METHODS

An Agilent human miRNA microarray was used to screen the differentially expressed miRNAs (DEMs) in LACC and LACC-HGT tumor tissues. Then, the primary cells obtained in previous studies were used to determine the effect of miR-29a-3p.

RESULTS

The expression of miR-29a-3p was abnormally lower in LACC-HGT than in LACC. miR-29a-3p can specifically target the 3' UTR of Quaking mRNA and down-regulate Quaking expression, thereby inhibiting the proliferation, migration, and epithelial-mesenchymal transition of LACC cells.

CONCLUSIONS

This study illustrated that miR-29a-3p functions as a tumor suppressor by down-regulating the expression of Quaking to inhibit the tumorigenesis of LACC cells. This study may also reveal the pathogenesis of HGT in LACC cells and provide a reference for LACC-HGT targeted diagnosis.

Bioinformatics identification of the candidate microRNAs and construction of a competing endogenous RNA regulatory network in lacrimal gland adenoid cystic carcinoma high-grade transformation

Adenoid cystic carcinoma of the lacrimal gland (LACC) is a major orbital malignancy. The recurrence rate and mortality rate are higher in LACC high-grade transformation (LACC-HGT) compared with in LACC. The present study aimed to identify the candidate microRNAs (miRNAs/miRs) and construct a competing endogenous RNA (ceRNA) regulatory network for LACC-HGT. A miRNA microarray on paraffin-embedded tissues was performed to identify the differentially expressed miRNAs (DEMs) of LACC-HGT. The overlap with the salivary adenoid cystic carcinoma miRNA/RNA sequencing dataset in the Gene Expression Omnibus was used to identify candidate miRNAs. In order to construct a ceRNA regulatory network of LACC-HGT, a microarray of mRNA and circRNA in primary cell lines was performed. The circRNAs and genes with high expression in LACC-HGT were predicted as targeting miRNAs, and the circRNA-miRNA-mRNA regulatory network was constructed. miR-140-3p was identified as part of the ceRNA network and as a candidate miRNA, therefore this was further analyzed using reverse transcription-quantitative (RT-q)PCR. Overall, the Agilent Human microarray analysis identified a total of 16 DEMs from the LACC-HGT paraffin-embedded tissues. A total of 653 DECs and 9,566 DEGs of LACC-HGT primary cell lines were screened via the microarray of mRNA and circRNA. The ceRNA regulatory network was constructed using the cross-binding of circRNA-miRNA, miRNA-mRNA and the downregulated miRNAs in LACC-HGT to clearly demonstrate the circRNA-miRNA-mRNA interaction relationship. RT-qPCR results confirmed that miR-140-3p was downregulated in LACC-HGT tissues and primary cell lines compared with LACC. Target genes CD200 and parathyroid hormone-related protein were significantly upregulated in LACC-HGT primary cell lines. miR-140-3p and its target genes may play an important role in LACC-HGT pathogenesis. In conclusion, the current bioinformatics study constructed a ceRNA network based on a microarray, which may help identify novel miRNA therapeutic targets for LACC-HGT.

Lacrimal gland adenocarcinoma responding to checkpoint inhibition and androgen deprivation

Although the histologically diverse classification of salivary gland tumors can be successfully applied to the epithelial lacrimal gland neoplasms, it is not clear whether the molecular makeup differs between these two different tumor types. Adenocarcinomas have known to have driver mutations in non-small cell lung cancer, however, besides HER2 expression not much is known regarding molecular drivers in lacrimal tumors. Androgen receptor (AR) expression and deprivation combined with checkpoint inhibition (CPI) have not been described before in lacrimal gland adenocarcinoma. To our knowledge, this is the first case report describing a prolonged response to CPI and AR inhibitors.

miR-24-3p Suppresses Malignant Behavior of Lacrimal Adenoid Cystic Carcinoma by Targeting PRKCH to Regulate p53/p21 Pathway

MicroRNA (miRNA) may function as an oncogene or a tumor suppressor in tumorigenesis. However, the mechanism of miRNAs in adenoid cystic carcinoma (ACC) is unclear. Here, we provide evidence that miR-24-3p was downreglated and functions as a tumor suppressor in human lacrimal adenoid cystic carcinoma by suppressing proliferation and migration/invasion while promoting apoptosis. miR-24-3p down-regulated protein kinase C eta (PRKCH) by binding to its untranslated region (3’UTR). PRKCH increased the of the cell growth and migration/invasion in ACC cells and suppressed the expression of p53 and p21 in both mRNA and protein level. The overexpression of miR-24-3p decreased its malignant phenotype. Ectopic expression of PRKCH counteracted the suppression of malignancy induced by miR-24-3p, as well as ectopic expression of miR-24-3p rescued the suppression of PRKCH in the p53/p21 pathway. These results suggest that miR-24-3p promotes the p53/p21 pathway by down-regulating PRKCH expression in lacrimal adenoid cystic carcinoma cells.

Adjuvant Radiotherapy with Three-Dimensional Conformal Radiotherapy of Lacrimal Gland Adenoid Cystic Carcinoma

BACKGROUND & AIM

Adenoid cystic carcinoma (ACC) of lacrimal gland is a rare tumour with aggressive behaviour. There is sparse data to address optimum therapy for such tumours. So, the present study was aimed at evaluating the role of adjuvant three dimensional conformal radiotherapy (3D-CRT) in cases of incomplete (R1) resection along with review of literature pertaining to management of lacrimal adenoid cystic carcinoma.

MATERIALS AND METHODS

We retrospectively reviewed the demographic and treatment data of 10 biopsy proven ACC of lacrimal gland patients, treated from December 2006 to June 2013. They were treated with radiotherapy following surgical resection. Eight patients underwent gross total excision of the tumour mass (enbloc excision) followed by conformal radiotherapy to a dose of 60 Gray/30fractions/ 6 weeks. Two patients with advanced disease were treated with palliative radiotherapy after biopsy.

RESULTS

The median age was 32 years. There were equal numbers of male and female patients. The median duration of symptoms was 7 months. At a median follow up of 21 months, eight patients had no evidence of disease and had complete tumour response, two patients worsened, and one of the two had systemic failure with bone metastasis.

CONCLUSION

Despite a small sample size and short follow, enbloc surgical excision with adjuvant radiotherapy is well tolerated and shows good control in ACC of lacrimal gland.

Metastatic, her-2 amplified lacrimal gland carcinoma with response to lapatinib treatment

Carcinoma of the lacrimal gland is a rare malignancy, limiting opportunities to develop new therapeutic regimens through clinical trials. There are no standard guidelines on optimal treatment of lacrimal gland carcinoma. In addition, lacrimal gland carcinoma includes several different subtypes with distinct behavior and response to treatment, further complicating treatment. Overexpression of the Her-2/neu protein, a potential target for new therapeutic agents, has previously been described in lacrimal gland carcinoma; however, there are no published reports regarding treatment of lacrimal gland cancer with Her-2 directed medications. This case report describes treatment of a patient with metastatic lacrimal gland carcinoma with lapatinib, an oral agent with activity against Her-2/neu amplified malignancies. In this case, Her-2 overexpression was confirmed by biopsy of a metastatic site. PET imaging obtained 6 months after the initiation of lapatinib showed evidence of a partial response to treatment, although the patient later developed progressive neurologic complications related to her malignancy and ultimately died. Lapatinib and other Her-2 targeted agents may represent an effective therapeutic option for this rare malignancy, in cases of metastatic disease.