Hiroyuki Goda

Knockdown of Akt isoforms by RNA silencing suppresses the growth of human prostate cancer cells in vitro and in vivo

The serine/threonine kinase Akt has three highly homologous isoforms in mammals: Akt1, Akt2, and Akt3. Recent studies indicate that Akt is often constitutively active in many types of human malignancy. Here we investigated the expression and function of Akt isoforms in human prostatic carcinoma cells. Initially, we used Western blotting to examine Akt expression in four human prostate cancer cell lines. Next, small-interfering RNAs (siRNAs) specific for Akt isoforms were used to elucidate their role on the in vitro and in vivo growth of prostate cancer cells. Expression of Akt1 and Akt2 was detected in all cells tested, but Akt3 was expressed only in cancer cells that did not express androgen receptors. All synthetic siRNAs against Akt isoforms suppressed their expression and inhibited the growth of cancer cells in vitro. Furthermore, atelocollagen-mediated systemic administration of siRNAs significantly reduced the growth of tumors that had been subcutaneously xenografted. These results suggest that targeting Akt isoforms could be an effective treatment for prostate cancers.

Role of Akt isoforms in HGF-induced invasive growth of human salivary gland cancer cells

The expression of hepatocyte growth factor (HGF) and c-Met is associated with tumor progression in many human malignancies. A recent study demonstrated HGF and c-Met expression in human salivary gland cancer tissues. Here, we investigated the role of the HGF/c-Met system in the invasive growth of two human salivary gland cancer cell lines: green fluorescent protein-adenoid cystic carcinoma 2 (GFP-ACC2) and GFP-ACCM. HGF enhanced the invasive growth of the two cell lines by activating PI3K/Akt signaling. All Akt isoforms (Akt1, Akt2, and Akt3) were detected in both cell types by Western blot analysis. Knockdown of any of the Akt isoforms using isoform-specific synthetic small-interfering RNAs largely abrogated the invasive growth induced by HGF. Our findings suggest that all of the Akt isoforms are required for the HGF-stimulated invasive growth of human salivary gland cancer cells, and that targeting a single Akt isoform could be effective in treating salivary gland cancers.

Prognostic significance of interleukin-8 and CD163-positive cell-infiltration in tumor tissues in patients with oral squamous cell carcinoma

Purpose We investigated whether serum interleukin (IL)-8 reflects the tumor microenvironment and has prognostic value in patients with oral squamous cell carcinoma (OSCC). Experimental Design Fifty OSCC patients who received radical resection of their tumor(s) were enrolled. Preoperative sera were measured for IL-8 by ELISA. Expression of IL-8 and the infiltration of immune cells in tumor tissues were analyzed by an immunohistochemical staining of surgical specimens. Results We found that disease-free survival (DFS) was significantly longer in the Stage I/II OSCC patients with low serum IL-8 levels compared to those with high levels (p = 0.001). The tumor expression of IL-8, i.e., IL-8(T) and the density of CD163-positive cells in the tumor invasive front, i.e., CD163(IF) were correlated with the serum IL-8 level (p = 0.033 and p = 0.038, respectively), and they were associated with poor clinical outcome (p = 0.007 and p = 0.002, respectively, in DFS) in all patients. A multivariate analysis revealed that N status, IL-8(T) and CD163(IF) significantly affected the DFS of the patients. Further analysis suggested that combination of N status with serum IL-8, IL-8(T) or CD163(IF) may be a new criterion for discriminating between OSCC patients at high and low risk for tumor relapse. Interestingly, the in vitro experiments demonstrated that IL-8 enhanced generation of CD163-positive M2 macrophages from peripheral blood monocytes, and that the cells produced IL-10. Conclusions These findings indicate that IL-8 may be involved in poor clinical outcomes via generation of CD163-positive M2 macrophages, and that these factors in addition to N status may have prognostic value in patients with resectable OSCSS.

CD151 regulates HGF-stimulated morphogenesis of human breast cancer cells

We previously demonstrated that CD151 forms a functional complex with c-Met and integrin alpha3/alpha6 in human salivary gland cancer cells. In the current study, we investigated the involvement of CD151, c-Met, and integrin alpha3/alpha6 in the cellular morphogenesis of human breast cancer cells. Knockdown of CD151, integrin alpha3, or integrin alpha6 expression abolished branching morphogenesis. Decreased c-Met expression in these cells led to the formation of rudimentary networks and prevented their conversion. Furthermore, hepatocyte growth factor (HGF) promoted cellular morphogenesis by accelerating network reorganization. Immunoprecipitation revealed a specific association between CD151 and c-Met. The involvement of CD151 and integrin alpha3/alpha6 in HGF-dependent signaling was confirmed by the decreased Akt phosphorylation in cells lacking CD151, integrin alpha3, or integrin alpha6. Hence, the regulation of CD151 expression might contribute to changes in HGF/c-Met signaling and thereby modulate the phenotypic characteristics of cancer cells.

Anti-tumor effect of small interfering RNA targeting the androgen receptor in human androgen-independent prostate cancer cells.

Early phase prostate cancer is usually androgen-dependent, with the androgen/androgen receptor (AR) signaling pathway playing a central role. At this stage, the cancer responds well to androgen ablation therapy, but prostate cancers eventually acquire androgen independence and more aggressive phenotypes. Several studies, however, have shown that the majority of tumors still express functional AR, which is often amplified and mutated. To determine if the AR is a plausible therapeutic target, we investigated the anti-tumor effect of small interfering RNAs targeting the AR (siAR) in the human prostate cancer cells, LNCaP and 22Rv1, which express mutated AR. In both types of cells, transfection of siAR suppressed mutated AR expression and significantly reduced cell growth. Furthermore, atelocollagen-mediated systemic siAR administration markedly inhibited the growth of 22Rv1 cells subcutaneously xenografted in castrated nude mice. These results suggest that the AR is still a key therapeutic target even in androgen-independent prostate cancer (AIPC). Silencing of AR expression in AIPC opens promising therapeutic perspectives.

One-step nucleic acid amplification for detecting lymph node metastasis of head and neck squamous cell carcinoma.

OBJECTIVES Lymph node stage is an important prognostic factor in head and neck squamous cell carcinoma (HNSCC). We previously reported the clinical usefulness of sentinel lymph node biopsy diagnosed by genetic analysis using quantitative RT-PCR. However, this method takes about 3h. In this study, we attempted to develop a more efficient method for the intraoperative genetic detection of lymph node metastasis in HNSCC. MATERIALS AND METHODS A total of 312 lymph nodes (65 patients) were diagnosed by the one-step nucleic acid amplification (OSNA) method using GD-100. OSNA consists of a short homogenization step followed by amplification of cytokeratin 19 (CK19) mRNA directly from the lysate. Each lymph node was divided into two to diagnose metastasis. One half was used for the OSNA assay, and the other was subjected to semi-serial sectioning, sliced at 200-μm intervals and examined by H&E and cytokeratin AE1/AE3 immunohistochemical staining. The accuracy of OSNA assay was evaluated based on histopathological diagnosis. RESULTS Sixty-one of 312 lymph nodes were pathologically metastasis-positive. The overall concordance rate between the OSNA assay using breast cancer criteria and histopathology was 94.2%. The optimal cut-off for the copy number of CK19 mRNA in assessing lymph node metastasis of HNSCC was 300 copies/μl, which had the highest diagnostic accuracy (95.2%). The OSNA assay can be completed within 30 min. CONCLUSION The OSNA assay, which shows high sensitivity and specificity, suggests the possibility to be used as a novel tool for the genetic detection of lymph node metastasis in HNSCC patients.

Double sentinel lymph node mapping with indocyanine green and 99m-technetium–tin colloid in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) frequently metastasizes to cervical lymph nodes, which is the most known prognostic factor. Screening methods to identify sentinel lymph nodes (SLNs) are therefore of great interest for the management of potential neck metastasis. The purpose of this study was to evaluate the clinical benefit of double SLN mapping with indocyanine green (ICG) and 99m-technetium-tin colloid ((99m)Tc-tin colloid) for sentinel node navigation surgery (SNNS). Between 2007 and 2010, 16 patients diagnosed with OSCC were investigated by SLN biopsy using the double mapping method. (99m)Tc-tin colloid was injected into the peri-tumoural region on the preoperative day, and ICG was administered intraoperatively in the same position to assist in detecting nodes during surgery. Based on the gamma-ray signal and near-infrared (NIR) fluorescence of ICG, SLNs were identified and thereafter assessed pathologically and genetically for cancer involvement. Radio-guided detection was successful for all patients. ICG mapping identified a relatively larger number of nodes, suggesting that several non-SLNs were potentially involved. The double mapping method assisted surgeons to explore SLNs. Since the ICG fluorescence was shielded by the subcutaneous fatty tissue and the muscle layer including platysma and sternocleidomastoid, it was necessary to retract the tissue away from nodes.

Identification of Akt1 as a potent therapeutic target for oral squamous cell carcinoma

Oncogene addiction can provide therapeutic opportunities in human malignancies. In this study, we aimed to identify critical oncogenes for oral squamous cell carcinoma (OSCC) development and progression. We determined gene expression profiles in 10 primary OSCCs and 10 human OSCC cell lines using Applied Biosystems Human Genome Survey Arrays. Akt1 was the only gene identified that was expressed in all OSCC tissues and cultured cells, but not in non-neoplastic tissues and cells. Subsequently, western blot analysis showed that Akt1 protein was overexpressed in OSCC tissues and cell lines. Immunohistochemistry also showed Akt1 protein expression in 59 of 63 (94%) primary OSCCs. To clarify the oncogenic function of Akt1 in human OSCC cells, we used RNA interference. We designed and synthesized 5 small interfering RNAs specific for Akt1 (siAkt1). Transfecting human OSCC cells with siAkt1 in vitro markedly suppressed their expression of Akt1 protein and significantly reduced their growth rate. Furthermore, the growth of human OSCC tumors which had been subcutaneously xenografted in athymic nude mice lacking interferon responses was markedly inhibited by atelocollagen-mediated systemic siAkt1 administration. We also found that synthetic siAkt1 had an inhibitory effect on the growth of primary cultured OSCC cells. Finally, we investigated the molecular mechanisms involved in the growth inhibitory effect of Akt1 suppression using microarray analysis of human OSCC cells transfected with siAkt1. Knockdown of Akt1 induced the expression of CDKN2B, a tumor suppressor gene, and reduced the expression of TGFBR1, which supports malignant phenotypes. These results suggest that Akt1 functions as a critical oncogene in human OSCC cells and may therefore be an appropriate target for novel OSCC therapies.

Abstract 145: MicroRNA-361-3p functions as an oncogenic microRNA in human oral cancer cells

MicroRNAs (miRNAs) are small non-coding double-stranded RNA with sizes of 20-25 nucleotides, and inhibit protein translation by binding the 39-untranslated region of target mRNA. Each miRNA can regulate multiple mRNAs and each mRNA can be targeted by a number of miRNAs. In cancer, miRNAs can act as not only tumor suppressor genes but also oncogenes (OncomiR). Most recent study has demonstrated OncomiR addiction in mouse pre-B-cell lymphoma. OncomiR addiction may also provide therapeutic opportunities in human cancers such as oncogene addiction. In this study, we have attempted to identify an OncomiR in human oral cancer cells through functional screening and considered whether targeting miRNA can be possible for cancer therapy. First, we performed functional screening for OncomiR in human oral cancer cells by the use of miRCURY LNATM microRNA Knockdown Library (Exiqon). We transfected 918 locked nucleic acid (LNA) antisense oligonucleotides for specific human mature miRNAs into human oral squamous cell carcinoma cells (GFP-SAS) and salivary gland cancer cells (GFP-ACCM). After transfection for 80 hours, each cell growth was evaluated. LNA antisense oligonucleotides against microRNA-361-3p (LNA-miR-361-3p) showed a remarkable growth inhibition in both types of cells as compared with non-targeting LNA oligonucleotides. We also observed the change of cell morphology, diminution of colony size, and a number of non-adherent cells after transfection of LNA-miR-361-3p. Subsequently, we examined the knockdown effect of LNA-miR-361-3p in GFP-SAS cells by quantitative RT-PCR. Compared with control oligonucleotides, the expression of miR-361-3p was significantly reduced by 71%. These effects of LNA-miR-361-3p were not observed by transfection of DNA or RNA antisense oligonucleotides for miR-361-3p. Next, we transfected synthetic human mature miR-361-3p into GFP-SAS cells to investigate the effect of miR-361-3p overexpression. Cell growth resulted in a significant 20% increase compared with non-targeting control miRNA. Furthermore, co-transfection of LNA-miR-361-3p and its decoy oligonucleotides abrogated the growth inhibitory effect by LNA-miR-361-3p in GFP-SAS cells. These results suggest that miR-361-3p functions as an OncomiR in human oral cancer cells and LNA antisense oligonucleotides are useful and efficient for silencing miRNA. Targeting miR-361-3p with LNA antisense oligonucleotides may be a useful therapeutic approach for patients with oral cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 145. doi:10.1158/1538-7445.AM2011-145

Annexin A8 is a novel molecular marker for detecting lymph node metastasis in oral squamous cell carcinoma.

Cervical lymph node metastasis is an important prognostic factor in oral squamous cell carcinoma (OSCC), but its accurate assessment after sentinel node biopsy or neck dissection is often limited to the histopathological examination of only one or two sections. Previous our study showed the usefulness of the reverse transcription loop-mediated isothermal amplification (RT-LAMP) targeting keratin 19 (KRT19) mRNA for the genetic detection of lymph node metastasis, but the sensitivity was insufficient. Here, we have attempted to identify novel molecular markers for OSCC cells in lymph nodes. We performed microarray analysis to identify genes overexpressed in 7 metastatic lymph nodes from OSCC patients, compared to 1 normal lymph node and 5 salivary glands from non-cancer patients. We then used real-time quantitative RT-PCR (qRT-PCR) and RT-LAMP to compare the expression of these genes in newly resected metastatic and normal lymph nodes. Of 4 genes identified by microarray analysis, annexin A8 (ANXA8) and desmoglein 3 mRNA were detected by qRT-PCR in metastatic lymph nodes but not in normal lymph nodes. Furthermore, ANXA8 mRNA expression was detected in all KRT19-negative metastatic lymph nodes. Both KRT19 and ANXA8 mRNA may be useful markers for detecting lymph node metastases in OSCC patients.