GJB5 association with BRAF mutation and survival in cutaneous malignant melanoma

BACKGROUND

Gap junctional intercellular communication is crucial for epidermal cellular homeostasis. Inability to establish melanocyte-keratinocytes contacts and loss of intercellular junction's integrity may contribute to melanoma development. Connexins, laminins and desmocollins have been implicated in the control of melanoma growth, where their reduced expression has been reported in metastatic lesions.

OBJECTIVES

The aim of this study was to investigate Connexin 31.1 (GJB5) expression and identify any association with BRAF mutational status, melanoma patient prognosis and MAPK inhibitors (MAPKi) treatment.

MATERIAL AND METHODS

GJB5 expression was measured at RNA and protein level in melanoma clinical samples and established cell lines treated or not with BRAF and MEK inhibitors, as well as in cell lines which developed MAPK inhibitors resistance. Findings were further validated and confirmed by analysis of independent datasets.

RESULTS

Our analysis reveals significant downregulation of GJB5 expression in metastatic melanoma lesions compared to primary ones and in BRAF mutated versus BRAF wild-type melanomas. Likewise, GJB5 expression is significantly lower in BRAF^V600E compared with BRAF^WT cell lines and increases upon MAPKi treatment. MAPKi-resistant melanoma cells display a similar expression pattern compared to BRAF^WT cells, with increased GJB5 expression associated with morphological changes. Enhancement of BRAF^V600E expression in BRAF^WT melanoma cells significantly upregulates miR-335-5p expression with consequent downregulation of GJB5, one of its targets. Furthermore, overexpression of miR-335-5p in two BRAF^WT cell lines confirms specific GJB5 protein downregulation. RT-qPCR analysis also revealed upregulation of miR-335 in BRAF^V600E melanoma cells, which is significantly downregulated in cells resistant to MEK inhibitors. Our data were further validated using the TCGA-SKCM dataset, where BRAF mutations associate with increased miR-335 expression and inversely correlate with GJB5 expression. In clinical samples, GJB5 underexpression is also associated with patient overall worse survival, especially at early stages.

CONCLUSION

We identified a significant association between metastases / BRAF mutation and low GJB5 expression in melanoma. Our results identify a novel mechanism of Gap-junctional protein regulation, suggesting a prognostic role for GJB5 in cutaneous melanoma.

Interobserver Reproducibility of Immunohistochemical Her-2/Neu Assessment in Human Breast Cancer: An Update from INQAT round III

The clinical interest in HER-2/neu is related to trastuzumab, a drug used to treat patients with invasive breast carcinoma overexpressing the HER-2/neu protein. It is very important to correctly identify those patients who may benefit from trastuzumab by accurate assessment of the HER-2/neu status. Of the various methods available, the Dako Herceptest for immunohistochemical assay is considered the most reliable to reach this goal. The aim of this study was to investigate within a group of Italian laboratories the reproducibility of the results of HER-2/neu assessment by means of the Dako scoring system on slides stained with the Herceptest kit. This study was also conceived as the continuation of one of our previous studies, which was similar in its aims but different in the classification criteria adopted. Our results show that, whereas the intra-observer reproducibility was generally satisfactory, the interobserver reproducibility was not. Moreover, our findings confirm that the two extreme classes (0 and 3+) are more easy to identify than the other two and that the Herceptest does not allow to discriminate optimally between scoring classes 2+ and 3+. These findings are relevant in clinical practice where the treatment choice is based on categories defined by this assay, suggesting the need of adopting educational programs and/or new reference materials to improve the assay performance.

Abstract P1-09-21: Clinical evaluation of miR-100 as a predictor of endocrine-responsiveness in hormone-receptor positive breast cancer

Background: Micro RNAs (miRNAs) are short, non-coding RNA molecules that act as negative regulators of gene-expression, mainly at the post-transcriptional level. Alterations in miRNA functions have been implicated in a variety of human diseases, including cancer

We demonstrated that the ectopic expression of miR-100 in cancer stem cells (CSCs) derived from aggressive, basal-like BC (HRs and HER2 negative) caused loss of stemness and the acquisition of a hormone receptor positive and endocrine treatment sensitive phenotype (Petrelli et al, Oncotarget 6;2315-30, 2015). We therefore sought to study whether miR-100 is a determinant of the endocrine-responsive phenotype in HR-positive BC patients (pts).

Methods: Women with newly diagnosed, estrogen-receptor and/or progesterone-receptor positive, HER2 negative BC were eligible for this study. Treatment consisting of tamoxifen for pre-menopausal and letrozole for post-menopausal pts was administered daily for 21 days (+/- 3 days) before breast surgery. MiR-100 levels in pre-treatment tumor biopsies, measured as fold-change with respect to a reference RNA and transformed to the natural logarithms to normalize the data, were correlated with proliferative response to endocrine therapy, as measured by Ki67 expression in the final surgical specimen. The primary end-point was a complete proliferative response (CPR), defined as a post-treatment Ki67≤1%. Additionally, we considered a “post-hoc” composite endpoint where response was defined as a post treatment Ki67 <10% together with a Ki67 reduction ≥80% compared to pre-treatment values. The target accrual is 88 patients (pts). Here we report the results of the first interim analysis focusing on post-menopausal pts receiving letrozole.

Results: A total of 42 pts were evaluable for miR-100 levels and response to endocrine therapy. Median ER and PgR expression was 99% (58%-99%) and 96% (0-99%) respectively. Median pre-treatment Ki67 was 18% (5-76%). Thirty-one tumors were ductal carcinomas, 9 were lobular and 2 were “other” histotypes. The median (range) miR-100 values in pre-treatment specimens was 2.253 (0.460-3.750). After treatment, median Ki67 was 4% (1%-46%) and the median percentage variation with respect to baseline values was -74% (0% to -94%). A CPR was observed in 5/42 pts (12%, 95% C.I. 5%-25%). The median miR-100 levels in responders and non-responders were 3.058 and 2.198, respectively (p = 0.03). Logistic regression analysis showed that each unit increase in miR-100 was associated with a 7-fold increase in the likelihood of a CPR (OR 7.056, 95% C.I. 1.103-45.141, p = 0.04).

Considering the composite end-point, 17/42 pts (40%, 95% C.I. 27%-56%) were considered responders. Median miR-100 levels in responders and non-responders were 2.427 and 1.956, respectively (p = 0.05).

Conclusions: preliminary results of this prospective clinical trial suggest that miR-100 can be a modulator of the endocrine-responsive phenotype in post-m pts with HR-positive breast cancer. The study is completing its target accrual and an investigation of miR-100 targets is being conducted.

GZ and AP contributed equally to this work.

Supported by Associazione Italiana per la Ricerca Sul Cancro (Investigator Grant IG-2013 Ref. 14451).

Citation Format: Zucchini G, Petrelli A, Kubatzki F, Cargnelutti M, Di Virgilio MR, Sarotto I, Martincich L, Ponzone R, Martinello R, Sapino A, Nuzzo A, Giordano S, Montemurro F. Clinical evaluation of miR-100 as a predictor of endocrine-responsiveness in hormone-receptor positive breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-09-21.

P3-07-04: Does Omission of Axillary Dissection after a Positive Sentinel Node Biopsy Influence Indication to Adjuvant Chemotherapy in Operable Breast Cancer Patients?

Introduction: Based on the recently published ACSOG Z0011 study (JAMA 2011;305:569), axillary dissection (AD) may be avoided in breast cancer (BC) patients with a clinically negative axilla and a positive sentinel lymph node (SLN) biopsy receiving breast conserving surgery (BCS). Because the number of positive axillary lymph nodes (ALN) is a widely accepted prognostic marker, we evaluated the potential impact of omission of AD on indication to adjuvant chemotherapy (ACT).

Patients and methods: Among 1497 patients operated at our Institution over 10 years, we identified 321 patients fulfilling the inclusion criteria of the ACSOG Z0011 study (BCS plus SLNB, cT1-2, cN0 breast cancer and 1 to 2 positive SLN). All patients underwent AD. Each case, which was anonymized, was reviewed by our breast team in two rounds. In the first round, patient age, histopathology, linfovascular invasion, tumor grade, hormone receptor, HER2, and ki67 status and number of positive SN nodes (micro and/or macrometastatic) were available. In the second round, the information on ALN was added. At each round, the panel chose between three indications: 1) Recommend ACT; 2) Discuss ACT; 3) No ACT. Results: SN was micrometastatic in 145 (45%) and macrometastatic in 176 patients (55%). ALD revealed non-SNs metastases in 96 patients (30%). Forty-four of these patients had >3 positive ALN (range 4–24). Indications at round 1 and 2 are summarized below.

P2-12-31: Moderate Immunohistochemical Expression of HER2 (2+) without HER2 Gene-Amplification Is a Negative Prognostic Factor in Early Breast Cancer

Purpose: We sought to evaluate whether moderate HER2 immunohistochemical (IHC) expression (2+ and no HER2/amplification) identifies early breast cancer (EBC) with a distinct prognostic profile.

Methods: A total of 1295 women (median age 58, range 22–94) undergoing surgery for EBC from Jan 1995 to Sept 2009 were retrospectively reviewed. All patients had undergone HER2 testing by the HercepTest and, when needed, by fluorescence in-situ hybridization (FISH). All tests were carried on at our Institutional Surgical Pathology laboratory. The impact of HER2 status on disease-free survival (DFS) was corrected for other clinical and pathological potential covariates by Cox Proportional Regression Analysis.

Results: A total of 494 (38%), 486 (38%), 119 (9%) and 196 (15%) of the patients had HER2 0+, 1+ 2+ and positive (3+ or FISH+) tumors, respectively. Sixty-one of 196 patients with HER2−positive EBC received adjuvant trastuzumab. A total of 298 DFS events occurred at median follow-up of 59 months (4-137 months). By using HER2 0+ status as reference, multivariate analysis revealed that HER2 2+ expression was associated with a significant increase in the risk of a DFS event (HR 2.303, 95% C.I. 1.501−3.533, p<0.001), whereas HER2 1+ was not (HR 0.976, 95% C.I. 0.698−1.365, p=0.889). We performed exploratory two-group comparisons by further classifying tumors according to hormone-receptor status (cutoff for ER and PgR positivity ≥10% of stained cells). Results are summarized in the table. HER2 2+ expression was associated with worse prognosis in both ER and/or PgR positive and ER/PgR negative tumors. In the latter group, HER2 2+ expression was associated with a particularly high rate of DFS events, with a 60-month projected DFS of 20%. Furthermore, while DFS curves plateaued at 60 months for HER2−positive tumors (with and without adjuvant trastuzumab) and for ER/PgR negative tumors with HER2 0/1+ expression, hormone receptor positive/HER2 2+ tumors displayed a particularly high rate of late relapses (beyond 60 months). Results did not change using a 1% cutoff to define ER and PgR positivity.

Conclusion: Moderate HER2 positivity (IHC 2+/FISH negative) identifies EBC patients at increased risk of a DFS event, regardless of hormone receptor status. Due to suggestions from large randomized trials that the benefits of trastuzumab may not be limited to HER2−positive tumors, patients with HER2 2+ EBC are ideal candidates for studies testing this hypothesis.

Multivariate Hazard Ratios, corrected by age, lymph-node status, tumor diameter, tumor grade, proliferation (Ki 67 index) and receipt of adjuvant chemotherapy

Somatic mutations of EGFR signal transducers and expression of tumor suppressor PTEN in biliary tract carcinoma

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Background: Biliary tract carcinomas express EGFR and are potential candidates to EGFR target therapies. We recently described somatic mutations of EGFR that can enhance MAPK or Akt activation (Clin Cancer Res, 2006). Some of them are identical to those previously reported to confer sensitivity to some tyrosine kinase inhibitors (TKIs) like erlotinib or gefitinib in lung cancer. Here we report a molecular analysis of EGFR transducers potentially involved in TKI response. Methods: In 49 samples of biliary tract carcinoma we performed mutational analysis of exons from 18 to 21 of EGFR, exons 9 and 20 of phosphatidylinositol 3’-kinase (PI3K), exon 2 of K-Ras, exon 15 of B-Raf and exons from 5 to 8 of PTEN. Nuclear PTEN expression was analyzed by immunohistochemistry and the expression in cancer cells was compared to that of normal cholangiocites. Results: Mutations of EGFR have been detected in 7 out of 49 samples (14.3%). One of them was a new stop-codon mutation. Five hotspot mutations of PI3K (codon 545, 546, 1048 and 1059) were found in 4 cases (8.2%); 3 cases (6.1%) had single mutations in K-Ras and 4 (8.2%) had the V599E mutation in B-Raf. In some samples, mutations of multiple trasducers were present simultaneously. PI3K mutations were significantly more frequent in EGFR mutated samples compared to wild type (28% vs. 4.7% respectively, p<0.05). A single F271L mutation of PTEN was observed (2%). We did not find loss of nuclear PTEN in biliary tract carcinoma cells; rather, a stronger labelling intensity (score 2+ or 3+) was present in biliary tract carcinoma compared to normal cholangiocites (score 1+). Moreover, the median percentage of PTEN labeled nuclei in tumor cells was 31.8%, but in samples with activating EGFR mutation was 60%, suggesting that a compensatory change in the level of the phosphatase might counteract the EGFR activition. Conclusions: These results corroborate our previous finding of EGFR pathway activation in EGFR mutated biliary tract carcinoma and suggest that an accurate analysis of the entire series of EGFR transducers may be done before planning treatments with TKIs.

No significant financial relationships to disclose.

Serum bile acids, programmed cell death and cell proliferation in the mucosa of patients with colorectal adenomas

BACKGROUND

Deoxycholic acid induced programmed cell death and an imbalance with cell proliferation may favour colorectal tumourigenesis according to 'in vitro' studies, but information is lacking on the relationships occurring 'in vivo' in humans.

AIMS

To evaluate whether serum deoxycholic acid is associated with programmed cell death and cell proliferation in colonic mucosa.

METHODS

In 10 patients with colorectal adenomas, we measured fasting serum levels of bile acids; and, in normal colonic mucosa, programmed cell death by the TUNEL technique and cell proliferation by immunohistochemical staining with anti-Ki67. Total and compartmental indices for both activities were calculated.

RESULTS

Among serum bile acids, only total deoxycholic acid (median: 0.89 micromol/L +/- 0.54 95% CI), showed a significant positive correlation with the total and basal compartments PCD Index (r = 0.68, p < 0.05). Total proliferation index showed no correlation with either total PCD Index, or bile acids. Within the median compartment of the crypt, cell proliferation was negatively associated with all unconjugated bile acids.

CONCLUSIONS

The positive association between deoxycholic acid and programmed cell death in the basal compartment of the crypt, and the negative association of cell proliferation and unconjugated bile acids in the median compartment, do not seem to support the co-carcinogenic effect of deoxycholic acid.

Resveratrol depresses the growth of colorectal aberrant crypt foci by affecting bax and p21(CIP) expression

We investigated whether resveratrol (RV) affects azoxymethane (AOM)-induced colon carcinogenesis, by administering RV (200 microg/kg/day in drinking water) to male F344 rats for 100 days, beginning 10 days before carcinogen treatment (two weekly doses of 15 mg/kg AOM). Aberrant crypt foci (ACF) were isolated and proliferation, apoptosis and expression of the cell cycle genes bax and p21 were determined. RV significantly reduced the number of ACF/colon [25.7 +/- 3.6 (mean +/- SEM) versus 39.4 +/- 3.3 in controls; P < 0.01] and their multiplicity (2.7 +/- 0.3 versus 4.9 +/- 0.6 in controls; P < 0.01), and also abolished large ACF. In RV-treated rats, bax expression was enhanced in ACF but not in the surrounding mucosa. In both controls and RV-treated rats, proliferation was higher in ACF than in normal mucosa. p21 was expressed in ACF of controls and of RV-treated rats and in normal mucosa of controls, but was lost in normal mucosa of RV-treated animals. In conclusion, the results suggest a protective role of RV in colon carcinogenesis with a mechanism involving changes in bax and p21 expression.

Resveratrol depresses the growth of colorectal aberrant crypt foci by affecting bax and p21(CIP) expression

We investigated whether resveratrol (RV) affects azoxymethane (AOM)-induced colon carcinogenesis, by administering RV (200 microg/kg/day in drinking water) to male F344 rats for 100 days, beginning 10 days before carcinogen treatment (two weekly doses of 15 mg/kg AOM). Aberrant crypt foci (ACF) were isolated and proliferation, apoptosis and expression of the cell cycle genes bax and p21 were determined. RV significantly reduced the number of ACF/colon [25.7 +/- 3.6 (mean +/- SEM) versus 39.4 +/- 3.3 in controls; P < 0.01] and their multiplicity (2.7 +/- 0.3 versus 4.9 +/- 0.6 in controls; P < 0.01), and also abolished large ACF. In RV-treated rats, bax expression was enhanced in ACF but not in the surrounding mucosa. In both controls and RV-treated rats, proliferation was higher in ACF than in normal mucosa. p21 was expressed in ACF of controls and of RV-treated rats and in normal mucosa of controls, but was lost in normal mucosa of RV-treated animals. In conclusion, the results suggest a protective role of RV in colon carcinogenesis with a mechanism involving changes in bax and p21 expression.

Programmed cell death, proliferating cell nuclear antigen and p53 expression in mouse colon mucosa during diet-induced tumorigenesis

Western-style diets (WDs) trigger and sustain the early phases of tumorigenesis in mouse colon, and when continued throughout the life span lead to the development of dysplastic crypts. In order to evaluate the roles both of cell proliferation and programmed cell death (PCD) in WD-induced tumorigenesis, immunohistochemical detection of proliferating nuclear antigen (PCNA), in situ end labeling (TUNEL) of DNA breaks, and p53 protein were carried out in mouse colonic mucosa during prolonged feeding of two WDs. PCNA Labeling Index of colonic crypts was significantly higher in WD-treated animals than in controls only at the beginning of the nutritional study, the gap rapidly bridged by increased cell proliferation spontaneously occurring in the colonic mucosa during aging. A transient early homeostatic activation of PCD at the base of the crypt also was observed in WD groups. No changes in PCD were seen in the upper third of the crypt or in surface epithelium throughout the study, indicating that PCD in that colonic crypt segment produces a constant flux of cell loss, uninfluenced by homeostatic fluctuations. A major finding was an irreversible, progressive, age-related decline of PCD at the crypt base in both control and treated animals that occurred during the second half of the rodents' life span. p53 protein was not immunohistochemically detected, suggesting that neither overexpression of wild-type nor mutated forms of the protein are involved in the above mentioned changes.

Bcl2, p53 and clinical outcome in a series of 138 operable breast cancer patients

Medical oncologists are increasingly interested in identifying reliable prognostic factors for breast cancer in order to distinguish subsets of breast cancer patients and to optimize therapeutic approaches. Among them, the p53 tumor suppressor gene and bcl2 protein continue to be extensively studied, but their role remains to be defined. Moreover the mechanism of action by which they affect cell kinetics has to be clarified, particularly with respect to the balance between cell proliferation and apoptosis. We studied 138 operable breast cancer patients in order to verify the relationships of p53 and bcl2 proteins with better known clinicopathological features and their impact on the clinical outcomes of relapse-free survival (RFS) and overall survival (OS). Our data indicated a significant relationship between bcl2 expression and steroid receptor positive status, wild-type p53 and low proliferative index. Mutant p53 accumulation was found to be related to the absence of steroid receptors and high proliferation. Both were significant markers of better prognosis in univariate analysis. Multivariate analysis confirmed the favorable impact of bcl2 on both RFS and OS. On the contrary, we failed to observe any prognostic role for p53 status. We describe herein an independent favorable prognostic impact for patients with positive bcl2 expression that appears to be worthy of larger confirmatory study. On the contrary, our series seems to confirm the decreasing prognostic relevance of p53 in clinical practice.

Gastrointestinal stromal tumor, uncommitted type, with monosomies 14 and 22 as the only chromosomal abnormalities

Karyotypic analysis of a gastric stromal tumor with the histologic and immunohistochemical features of a malignant, uncommitted lesion revealed clonal monosomies of chromosomes 14 and 22. Such changes, together with loss of chromosomes 15 and 18, as well as structural rearrangements involved chromosome 1, have been previously reported in gastrointestinal stromal tumors with smooth muscle differentiation. We suggest that monosomies of chromosomes 14 and 22 are early events in the malignant transformation of the mesenchymal cell-originating gastrointestinal stromal tumors.