A kinome-wide synthetic lethal CRISPR/Cas9 screen reveals that mTOR inhibition prevents adaptive resistance to CDK4/CDK6 blockade in HNSCC.

The comprehensive genomic analysis of the head and neck squamous cell carcinoma (HNSCC) oncogenome revealed the frequent loss of p16INK4A (CDKN2A) and amplification of cyclin D1 (CCND1) genes in most HPV negative HNSCC lesions. However, cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors have shown modest effects in the clinic. The aberrant activation of PI3K/mTOR pathway is highly prevalent in HNSCC, and recent clinical trials have shown promising clinical efficacy of mTOR inhibitors (mTORi) in the neoadjuvant and adjuvant settings but not in advanced HNSCC patients. By a kinome-wide CRISPR/Cas9 screen, we identified cell cycle inhibition as a synthetic lethal target for mTORi. Combination of mTORi and palbociclib, a CDK4/6 specific inhibitor, showed strong synergism in HNSCC-derived cells in vitro and in vivo. Remarkably, we found that adaptive increase in cyclin E1 (CCNE1) expression upon palbociclib treatment underlies the rapid acquired resistance to this CDK4/6 inhibitor. Mechanistically, mTORi inhibits the formation of eIF4G-CCNE1 mRNA complexes, with the consequent reduction in mRNA translation and CCNE1 protein expression. Our findings suggest that mTORi reverts the adaptive resistance to palbociclib. This provides a multimodal therapeutic option for HNSCC by co-targeting mTOR and CDK4/6, which in turn may halt the emergence of palbociclib resistance.

A genome-wide CRISPR screen reveals that antagonism of glutamine metabolism sensitizes head and neck squamous cell carcinoma to ferroptotic cell death.

Glutamine is a conditionally essential amino acid for the growth and survival of rapidly proliferating cancer cells. Many cancers are addicted to glutamine, and as a result, targeting glutamine metabolism has been explored clinically as a therapeutic approach. Glutamine-catalyzing enzymes are highly expressed in primary and metastatic head and neck squamous cell carcinoma (HNSCC). However, the nature of the glutamine-associated pathways in this aggressive cancer type has not been elucidated. Here, we explored the therapeutic potential of a broad glutamine antagonist, DRP-104 (sirpiglenastat), in HNSCC tumors and aimed at shedding light on glutamine-dependent pathways in this disease. We observed a potent antitumoral effect of sirpiglenastat in HPV- and HPV + HNSCC xenografts. We conducted a whole-genome CRISPR screen and metabolomics analyses to identify mechanisms of sensitivity and resistance to glutamine metabolism blockade. These approaches revealed that glutamine metabolism blockade results in the rapid buildup of polyunsaturated fatty acids (PUFAs) via autophagy nutrient-sensing pathways. Finally, our analysis demonstrated that GPX4 mediates the protection of HNSCC cells from accumulating toxic lipid peroxides; hence, glutamine blockade sensitizes HNSCC cells to ferroptosis cell death upon GPX4 inhibition. These findings demonstrate the therapeutic potential of sirpiglenastat in HNSCC and establish a novel link between glutamine metabolism and ferroptosis, which may be uniquely translated into targeted glutamine-ferroptosis combination therapies.

Tipifarnib Potentiates the Antitumor Effects of PI3Kα Inhibition in PIK3CA- and HRAS-Dysregulated HNSCC via Convergent Inhibition of mTOR Activity.

Outcomes for patients with recurrent/metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) are poor, with median overall survival (OS) ranging from 6 to 18 months. For those who progress on standard-of-care (chemo)immunotherapy, treatment options are limited, necessitating the development of rational therapeutic strategies. Toward this end, we targeted the key HNSCC drivers PI3K-mTOR and HRAS via the combination of tipifarnib, a farnesyltransferase (FTase) inhibitor, and alpelisib, a PI3Kα inhibitor, in multiple molecularly defined subsets of HNSCC. Tipifarnib synergized with alpelisib at the level of mTOR in PI3Kα- or HRAS-dependent HNSCCs, leading to marked cytotoxicity in vitro and tumor regression in vivo. On the basis of these findings, the KURRENT-HN trial was launched to evaluate the effectiveness of this combination in PIK3CA-mutant/amplified and/or HRAS-overexpressing R/M HNSCC. Preliminary evidence supports the clinical activity of this molecular biomarker-driven combination therapy. Combined alpelisib and tipifarnib has potential to benefit >45% of patients with R/M HNSCC. By blocking feedback reactivation of mTORC1, tipifarnib may prevent adaptive resistance to additional targeted therapies, enhancing their clinical utility. SIGNIFICANCE: The mechanistically designed, biomarker-matched strategy of combining alpelisib and tipifarnib is efficacious in PIK3CA- and HRAS-dysregulated head and neck squamous carcinoma and could improve outcomes for many patients with recurrent, metastatic disease. See related commentary by Lee et al., p. 3162.

Impact of Oncogenic Targets by Tumor-Suppressive miR-139-5p and miR-139-3p Regulation in Head and Neck Squamous Cell Carcinoma.

We newly generated an RNA-sequencing-based microRNA (miRNA) expression signature of head and neck squamous cell carcinoma (HNSCC). Analysis of the signature revealed that both strands of some miRNAs, including miR-139-5p (the guide strand) and miR-139-3p (the passenger strand) of miR-139, were downregulated in HNSCC tissues. Analysis of The Cancer Genome Atlas confirmed the low expression levels of miR-139 in HNSCC. Ectopic expression of these miRNAs attenuated the characteristics of cancer cell aggressiveness (e.g., cell proliferation, migration, and invasion). Our in silico analyses revealed a total of 28 putative targets regulated by pre-miR-139 (miR-139-5p and miR-139-3p) in HNSCC cells. Of these, the GNA12 (guanine nucleotide-binding protein subunit alpha-12) and OLR1 (oxidized low-density lipoprotein receptor 1) expression levels were identified as independent factors that predicted patient survival according to multivariate Cox regression analyses (p = 0.0018 and p = 0.0104, respectively). Direct regulation of GNA12 and OLR1 by miR-139-3p in HNSCC cells was confirmed through luciferase reporter assays. Moreover, overexpression of GNA12 and OLR1 was detected in clinical specimens of HNSCC through immunostaining. The involvement of miR-139-3p (the passenger strand) in the oncogenesis of HNSCC is a new concept in cancer biology. Our miRNA-based strategy will increase knowledge on the molecular pathogenesis of HNSCC.

Toxic epidermal necrolysis associated with nivolumab treatment for head and neck cancer.

This report is the first to document TEN caused by nivolumab treatment in head and neck cancer. We believe this article can contribute significantly in understanding the principles of nivolumab treatment in patients with head and neck cancer.

Regulation of Oncogenic Targets by miR-99a-3p (Passenger Strand of miR-99a-Duplex) in Head and Neck Squamous Cell Carcinoma.

To identify novel oncogenic targets in head and neck squamous cell carcinoma (HNSCC), we have analyzed antitumor microRNAs (miRNAs) and their controlled molecular networks in HNSCC cells. Based on our miRNA signature in HNSCC, both strands of the miR-99a-duplex (miR-99a-5p: the guide strand, and miR-99a-3p: the passenger strand) are downregulated in cancer tissues. Moreover, low expression of miR-99a-5p and miR-99a-3p significantly predicts poor prognosis in HNSCC, and these miRNAs regulate cancer cell migration and invasion. We previously showed that passenger strands of miRNAs have antitumor functions. Here, we screened miR-99a-3p-controlled oncogenes involved in HNSCC pathogenesis. Thirty-two genes were identified as miR-99a-3p-regulated genes, and 10 genes (STAMBP, TIMP4, TMEM14C, CANX, SUV420H1, HSP90B1, PDIA3, MTHFD2, BCAT1, and SLC22A15) significantly predicted 5-year overall survival. Notably, among these genes, STAMBP, TIMP4, TMEM14C, CANX, and SUV420H1 were independent prognostic markers of HNSCC by multivariate analyses. We further investigated the oncogenic function of STAMBP in HNSCC cells using knockdown assays. Our data demonstrated that the aggressiveness of phenotypes in HNSCC cells was attenuated by siSTAMBP transfection. Moreover, aberrant STAMBP expression was detected in HNSCC clinical specimens by immunohistochemistry. This strategy may contribute to the clarification of the molecular pathogenesis of this disease.

Dual strands of the miR-223 duplex (miR-223-5p and miR-223-3p) inhibit cancer cell aggressiveness: targeted genes are involved in bladder cancer pathogenesis.

Analyses of microRNA (miRNA) expression signatures obtained by RNA sequencing revealed that some passenger miRNAs (miR-144-5p, miR-145-3p, miR-149-3p, miR-150-3p, and miR-199a-3p) acted as anti-tumor miRNAs in several types of cancer cells. The involvement of passenger strands in the pathogenesis of human cancer is a novel concept. Based on the miRNA signature of bladder cancer (BC) obtained by RNA sequencing, we focused on both strands of the miR-223-duplex (miR-223-5p and miR-223-3p) and investigated their functional significance in BC cells. Ectopic expression of these miRNAs showed that both miR-223-3p (the guide strand) and miR-223-5p (the passenger strand) inhibited cancer cell migration and invasion of BC cells. The role of miR-223-5p (the passenger strand) has not been well studied. Combining gene expression studies and in silico database analyses, we demonstrated the presence of 20 putative target genes that could be regulated by miR-223-5p in BC cells. Among these targets, high expression of five genes (ANLN, INHBA, OIP5, CCNB1, and CDCA2) was significantly associated with poor prognosis of BC patients based on The Cancer Genome Atlas (TCGA) database. Moreover, we showed that a gene (ANLN) encoding a multifunctional actin-binding protein was directly regulated by miR-223-5p in BC cells. Overexpression of ANLN was observed in BC clinical specimens and high expression of ANLN was significantly associated with poor prognosis of BC patients. We suggest that studies of regulatory cancer networks, including the passenger strands of miRNAs, may provide new insights into the pathogenic mechanisms of BC.

Inhibition of integrin ß1-mediated oncogenic signalling by the antitumor microRNA-29 family in head and neck squamous cell carcinoma.

Due to their aggressive behavior, local recurrence and distant metastasis, survival rate of advanced stage of the patients with head and neck squamous cell carcinoma (HNSCC) is very poor. Currently available epidermal growth factor receptor (EGFR)-targeted therapies are not considered curative for HNSCC. Therefore, novel approaches for identification of therapeutic targets in HNSCC are needed. All members of the miRNA-29 family (miR-29a, miR-29b, and miR-29c) were downregulated in HNSCC tissues by analysis of RNA-sequencing based microRNA (miRNA) expression signature. Ectopic expression of mature miRNAs demonstrated that the miR-29 family inhibited cancer cell migration and invasion by HNSCC cell lines. Comprehensive gene expression studies and in silico database analyses were revealed that integrin ß1 (ITGB1) was regulated by the miR-29 family in HNSCC cells. Overexpression of ITGB1 was confirmed in HNSCC specimens, and high expression of ITGB1 significantly predicted poor survival in patients with HNSCC (p = 0.00463). Knockdown of ITGB1 significantly inhibited cancer cell migration and invasion through regulating downstream of ITGB1-mediated oncogenic signalling. In conclusion, regulation of the antitumor miR-29 family affected integrin-mediated oncogenic signalling to modulate HNSCC pathogenesis; these molecules may be novel therapeutic targets for HNSCC.

Downregulation of matrix metalloproteinase 14 by the antitumor miRNA, miR-150-5p, inhibits the aggressiveness of lung squamous cell carcinoma cells.

In the present study, in order to elucidate the aggressive nature of lung squamous cell carcinoma (LUSQ), we investigated the oncogenic RNA networks regulated by antitumor microRNAs (miRNAs or miRs) in LUSQ cells. The analysis of our original miRNA expression signatures of human cancers revealed that microRNA­150­5p (miR­150­5p) was downregulated in various types of cancer, indicating that miR­150­5p acts as an antitumor miRNA by targeting several oncogenic genes. Thus, the aims of this study were to investigate the antitumor roles of miR­150­5p in LUSQ cells and to identify oncogenes regulated by miR­150­5p that are involved in the aggressive behavior of LUSQ. The downregulation of miR­150­5p was validated in clinical samples of LUSQ and cell lines (SK-MES­1 and EBC­1). The ectopic overexpression of miR­150­5p significantly suppressed cancer cell aggressiveness. Comprehensive gene expression analyses revealed that miR­150­5p regulated 9 genes in the LUSQ cells. Among these, matrix metalloproteinase 14 (MMP14) was found to be a direct target of miR­150­5p, as shown by luciferase reporter assay. The knockdown of MMP14 using siRNA against MMP14 (si-MMP14) significantly inhibited cancer cell migration and invasion. The overexpression of MMP14 was detected in clinical specimens of LUSQ by immunohistochemistry. On the whole, these findings suggest that the downregulation of miR­150­5p and the overexpression of MMP14 may be deeply involved in the pathogenesis of LUSQ.

Antitumor miR-150-5p and miR-150-3p inhibit cancer cell aggressiveness by targeting SPOCK1 in head and neck squamous cell carcinoma.

OBJECTIVE: Our recent studies have revealed that both strands of pre-miRNAs, the guide strand and the passenger strand, are involved in cancer pathogenesis. Analyses of miRNA expression signatures by RNA sequencing in head and neck squamous cell carcinoma (HNSCC) showed that both of the strands of pre-miR-150 (miR-150-5p and miR-150-3p) were significantly downregulated, and that these miRNAs acted as antitumor miRNAs in HNSCC cells. The aim of this study was to identify oncogenic genes in HNSCC cells that were regulated by miR-150-5p and miR-150-3p. METHODS: Genome-wide gene expression studies, in silico analyses and dual-luciferase reporter assays were carried out to predict miR-150-5p and miR-150-3p regulation in HNSCC cells. Knockdown assay was applied to investigate the functional significance of the target gene. Overall patient survival as a function of target gene expression was estimated by The Cancer Genome Atlas (TCGA) database. RESULTS: A total of 19 genes were putative targets of both miR-150-5p and miR-150-3p regulation. Among them, SPOCK1 (SPARC/osteonectin, cwcv and kazal-like domains proteoglycan 1) was directly regulated by both miRNAs in HNSCC cells. Knockdown studies using si-SPOCK1 showed that expression of SPOCK1 enhanced HNSCC cell aggressiveness. Overexpression of SPOCK1/SPOCK1 was confirmed in HNSCC clinical specimens. Interestingly, analysis of a large number of patients in the TCGA database (n=248) demonstrated that patients with high SPOCK1 expression had significantly shorter survival than did those with low SPOCK1 expression (P=0.0003). Moreover, 15 pathways were identified as SPOCK1-mediated downstream pathways. CONCLUSION: Downregulation of both strands of pre-miR-150 (miR-150-5p and miR-150-3p) and overexpression of SPOCK1 contribute to the aggressive nature of HNSCC. The involvement of passenger strand miRNA in the regulation of HNSCC pathogenesis is a novel concept in RNA research.

Passenger strand of miR-145-3p acts as a tumor-suppressor by targeting MYO1B in head and neck squamous cell carcinoma.

Analysis of the microRNA (miRNA) expression signature of head and neck squamous cell carcinoma (HNSCC) based on RNA sequencing showed that dual strands of pre­miR­145 (miR­145­5p, guide strand; and miR­145­3p, passenger strand) were significantly reduced in cancer tissues. In miRNA biogenesis, passenger strands of miRNAs are degraded and have no biological activities in cells. The aims of this study were to investigate the functional significance of the passenger strand of miR­145 and to identify miR­145­3p­regulated oncogenic genes in HNSCC cells. Expression levels of miR­145­5p and miR­145­3p were significantly downregulated in HNSCC tissues and cell lines (SAS and HSC3 cells). Ectopic expression of miR­145­3p inhibited cancer cell proliferation, migration and invasion, similar to miR­145­5p, in HNSCC cells. Myosin 1B (MYO1B) was directly regulated by miR­145­3p, and knockdown of MYO1B by siRNA inhibited cancer cell aggressiveness. Overexpression of MYO1B was confirmed in HNSCC clinical specimens by analysis of protein and mRNA levels. Interestingly, high expression of MYO1B was associated with poor prognosis in patients with HNSCC by analysis of The Cancer Genome Atlas database (p=0.00452). Our data demonstrated that the passenger strand of miR­145 acted as an antitumor miRNA through targeting MYO1B in HNSCC cells. The involvement of dual strands of pre­miR­145 (miR­145­5p and miR­145­3p) in the regulation of HNSCC pathogenesis is a novel concept in present RNA research.

The microRNA expression signature of pancreatic ductal adenocarcinoma by RNA sequencing: anti-tumour functions of the microRNA-216 cluster.

We analysed the RNA sequence-based microRNA (miRNA) signature of pancreatic ductal adenocarcinoma (PDAC). Aberrantly expressed miRNAs were successfully identified in this signature. Using the PDAC signature, we focused on 4 clustered miRNAs, miR-216a-5p, miR-216a-3p, miR-216b-5p and miR-216b-3p on human chromosome 2p16.1. All members of the miR-216 cluster were significantly reduced in PDAC specimens. Ectopic expression of these miRNAs suppressed cancer cell aggressiveness, suggesting miR-216 cluster as anti-tumour miRNAs in PDAC cells. The impact of miR-216b-3p (passenger strand of pre-miR-216b) on cancer cells is still ambiguous. Forkhead box Q1 (FOXQ1) was directly regulated by miR-216b-3p and overexpression of FOXQ1 was confirmed in clinical specimens. High expression of FOXQ1 predicted a shorter survival of patients with PDAC by Kaplan-Meier analysis. Loss-of-function assays showed that cancer cell migration and invasion activities were significantly reduced by siFOXQ1 transfectants. We investigated pathways downstream from FOXQ1 by using genome-wide gene expression analysis. Identification of the miR-216-3p/FOXQ1-mediated network in PDAC should enhance understanding of PDAC aggressiveness at the molecular level.

Dual Strands of Pre-miR-149 Inhibit Cancer Cell Migration and Invasion through Targeting FOXM1 in Renal Cell Carcinoma.

Our recent studies revealed that dual strands of certain pre-microRNAs, e.g., pre-miR-144, pre-miR-145, and pre-miR-150, act as antitumor microRNAs (miRNAs) in several cancers. The involvement of passenger strands of miRNAs in cancer pathogenesis is a novel concept in miRNA research. The analysis of a miRNA expression signature in clear cell renal cell carcinoma (ccRCC) has revealed that the guide strand of pre-miR-149 is significantly downregulated in cancer tissues. The aims of this study were to investigate the functional significance of miR-149's guide strand (miR-149-5p) and passenger strand (miR-149-3p), and to identify the oncogenic genes regulated by these miRNAs in ccRCC cells. The ectopic expression of these miRNAs significantly inhibited cancer cell migration and invasion in ccRCC cells. Forkhead box protein M1 (FOXM1) was directly regulated by miR-149-5p and miR-149-3p in ccRCC cells. Knockdown studies using si-FOXM1 showed that the expression of FOXM1 enhanced RCC cell aggressiveness. Interestingly, the analysis of a large number of patients in the The Cancer Genome Atlas (TCGA) database (n = 260) demonstrated that patients with high FOXM1 expression had significantly shorter survival than did those with low FOXM1 expression (p = 1.5 × 10⁻6). Taken together, dual strands of pre-miR-149 (miR-149-5p and miR-149-3p) acted as antitumor miRNAs through the targeting of FOXM1 in ccRCC cells.

Involvement of aberrantly expressed microRNAs in the pathogenesis of head and neck squamous cell carcinoma.

MicroRNAs (miRNAs) are small noncoding RNAs that act as fine-tuners of the post-transcriptional control of protein-coding or noncoding RNAs by repressing translation or cleaving RNA transcripts in a sequence-dependent manner in cells. Accumulating evidence have been indicated that aberrantly expressed miRNAs are deeply involved in human pathogenesis, including cancers. Surprisingly, these small, single-stranded RNAs (18-23 nucleotides) have been shown to function as antitumor or oncogenic RNAs in several types of cancer cells. A single miRNA has regulating hundreds or thousands of different mRNAs, and individual mRNA has been regulated by multiple different miRNAs in normal cells. Therefore, tightly controlled RNA networks can be disrupted by dysregulated of miRNAs in cancer cells. Investigation of novel miRNA-mediated RNA networks in cancer cells could provide new insights in the field of cancer research. In this review, we focus on head and neck squamous cell carcinoma (HNSCC) and discuss current findings of the involvement of aberrantly expressed miRNAs in the pathogenesis of HNSCC.

Regulation of spindle and kinetochore-associated protein 1 by antitumor miR-10a-5p in renal cell carcinoma.

Analysis of our original microRNA (miRNA) expression signature of patients with advanced renal cell carcinoma (RCC) showed that microRNA-10a-5p (miR-10a-5p) was significantly downregulated in RCC specimens. The aims of the present study were to investigate the antitumor roles of miR-10a-5p and the novel cancer networks regulated by this miRNA in RCC cells. Downregulation of miR-10a-5p was confirmed in RCC tissues and RCC tissues from patients treated with tyrosine kinase inhibitors (TKI). Ectopic expression of miR-10a-5p in RCC cell lines (786-O and A498 cells) inhibited cancer cell migration and invasion. Spindle and kinetochore-associated protein 1 (SKA1) was identified as an antitumor miR-10a-5p target by genome-based approaches, and direct regulation was validated by luciferase reporter assays. Knockdown of SKA1 inhibited cancer cell migration and invasion in RCC cells. Overexpression of SKA1 was observed in RCC tissues and TKI-treated RCC tissues. Moreover, analysis of The Cancer Genome Atlas database demonstrated that low expression of miR-10a-5p and high expression of SKA1 were significantly associated with overall survival in patients with RCC. These findings showed that downregulation of miR-10a-5p and overexpression of the SKA1 axis were highly involved in RCC pathogenesis and resistance to TKI treatment in RCC.

Regulation of ITGA3 by the anti-tumor miR-199 family inhibits cancer cell migration and invasion in head and neck cancer.

For patients with head and neck squamous cell carcinoma (HNSCC), survival rates have not improved due to local recurrence and distant metastasis. Current targeted molecular therapies do not substantially benefit HNSCC patients. Therefore, it is necessary to use advanced genomic approaches to elucidate the molecular mechanisms underlying the aggressiveness of HNSCC cells. Analysis of our microRNA (miRNA) expression signature by RNA sequencing showed that the miR-199 family (miR-199a-5p, miR-199a-3p, miR-199b-5p and miR-199b-3p) was significantly reduced in cancer tissues. Ectopic expression of mature miRNA demonstrated that all members of the miR-199 family inhibited cancer cell migration and invasion by HNSCC cell lines (SAS and HSC3). These findings suggested that both passenger strands and guide strands of miRNA are involved in cancer pathogenesis. In silico database and genome-wide gene expression analyses revealed that the gene coding for integrin α3 (ITGA3) was regulated by all members of the miR-199 family in HNSCC cells. Knockdown of ITGA3 significantly inhibited cancer cell migration and invasion by HNSCC cells. Moreover, overexpression of ITGA3 was confirmed in HNSCC specimens, and high expression of ITGA3 predicted poorer survival of the patients (P = 0.0048). Our data revealed that both strands of pre-miR-199a (miR-199a-5p and miR-199a-3p) and pre-miR-199b (miR-199b-5p and miR-199b-3p) acted as anti-tumor miRNA in HNSCC cells. Importantly, the involvement of passenger strand miRNA in the regulation of cellular processes is a novel concept in RNA research. Novel miRNA-based approaches for HNSCC can be used to identify potential targets for the development of new therapeutic strategies.

Regulation of SPOCK1 by dual strands of pre-miR-150 inhibit cancer cell migration and invasion in esophageal squamous cell carcinoma.

Analysis of our microRNA (miRNA) expression signatures of human cancers based on RNA sequencing have shown that both strands of pre-miR-150, miR-150-5p (the guide strand) and miR-150-3p (the passenger strand), are significantly reduced in cancer tissues. We have investigated the functional significance of both strands of pre-miR-150 in cancer cells. The aim of this study was to investigate the antitumor function of these miRNAs and how these miRNAs regulated oncogenic targets in esophageal squamous cell carcinoma (ESCC). Ectopic expression studies demonstrated that both strands of pre-miR-150 miRNA inhibited ESCC cancer cell migration and invasion, indicating that both miR-150-5p and miR-150-3p acted as antitumor miRNAs. A combination of genome-wide gene expression analyses and in silico database searches showed that SPOCK1 (SPARC/osteonectin, cwcv and kazal-like domains proteoglycan 1) was a candidate target of miR-150-5p and miR-150-3p in ESCC cells. Luciferase reporter assays showed that SPOCK1 was directly regulated by these miRNAs. Silencing of SPOCK1 by small interfering RNA inhibited cancer cell migration and invasion. Overexpression of SPOCK1/SPOCK1 was confirmed by real-time PCR methods and immunohistochemistry. Taken together, downregulation of both strands of pre-miR-150 and overexpression of SPOCK1 are involved in ESCC pathogenesis. The involvement of passenger strand miRNAs in the regulation of cancer cell aggressiveness is a novel concept in RNA research.

Dual strands of pre-miR­150 (miR­150­5p and miR­150­3p) act as antitumor miRNAs targeting SPOCK1 in naïve and castration-resistant prostate cancer.

Analysis of our microRNA (miRNA) expression signature in human cancers has shown that guide and passenger strands of pre-miR­150, i.e., miR­150­5p and miR­150­3p, are significantly downregulated in cancer tissues. In miRNA biogenesis, the passenger strand of miRNA is degraded and is thought to have no functions. Thus, the aim of this study was to investigate the functional significance of miR­150­5p and miR­150­3p in naïve prostate cancer (PCa) and castration-resistant prostate cancer (CRPC). Ectopic expression assays showed that both strands of miRNAs significantly suppressed cancer cell migration and invasion. Our strategies of miRNA target searching demonstrated that SPOCK1 (SPARC/osteonectin, cwcv and kazal like domains proteoglycan 1) was directly regulated by miR­150­5p and miR­150­3p. Knockdown of SPOCK1 by siRNA inhibited cancer cell aggressiveness. Moreover, overexpression of SPOCK1 was observed in naïve PCa and CRPC tissues. Taken together, dual strands of pre-miR­150 (miR­150­5p and miR­150­3p) acted as antitumor miRNAs in naïve PCa and CRPC cells. Expression of oncogenic SPOCK1 was involved in naïve PCa and CRPC pathogenesis. Novel approaches to analysis of antitumor miRNA-regulated RNA networks in cancer cells may provide new insights into the pathogenic mechanisms of naïve PCa and CRPC.

Deep sequencing-based microRNA expression signatures in head and neck squamous cell carcinoma: dual strands of pre-miR-150 as antitumor miRNAs.

We adopted into RNA-sequencing technologies to construct the microRNA (miRNA) expression signature of head and neck squamous cell carcinoma (HNSCC). Our signature revealed that a total of 160 miRNAs (44 upregulated and 116 downregulated) were aberrantly expressed in cancer tissues. Expression of miR-150-5p (guide strand miRNA) and miR-150-3p (passenger strand miRNA) were significantly silenced in cancer tissues, suggesting both miRNAs act as antitumor miRNAs in HNSCC cells. Ectopic expression of mature miRNAs, miR-150-5p and miR-150-3p inhibited cancer cell aggressiveness. Low expression of miR-150-5p and miR-150-3p predicted significantly shorter overall survival in patients with HNSCC (P = 0.0091 and P = 0.0386) by Kaplan-Meier survival curves analyses. We identified that integrin α3 (ITGA3), integrin α6 (ITGA6), and tenascin C (TNC) were coordinately regulated by these miRNAs in HNSCC cells. Knockdown assays using siRNAs showed that ITGA3, ITGA6 and TNC acted as cancer promoting genes in HNSCC cells. Moreover, ITGA3, ITGA6, and TNC alterations were associated with significantly poorer overall survival (P = 0.0177, P = 0.0237, and P = 0.026, respectively). Dual strands of pre-150 (miR-150-5p and miR-150-3p) functioned as antitumor miRNAs based on the miRNA expression signature of HNSCC. Identification of antitumor miR-150-mediated RNA networks may provide novel insights into pathogenesis of HNSCC.

Regulation of metastasis-promoting LOXL2 gene expression by antitumor microRNAs in prostate cancer.

Our recent studies of microRNA (miRNA) expression signatures of prostate cancer (PCa) showed that six miRNAs (specifically, miR-26a, miR-26b, miR-29a, miR-29b, miR-29c and miR-218) were markedly reduced in cancer tissues. Moreover, ectopic expression of these miRNAs suppressed PCa cell aggressiveness, indicating that these miRNAs acted in concert to regulate genes that promoted metastasis. Genome-wide gene expression analysis and in silico database analysis identified a total of 35 candidate genes that promoted metastasis and were targeted by these 6 miRNAs. Using luciferase reporter assays, we showed that the lysyl oxidase-like 2 (LOXL2) gene was directly controlled by these tumor-suppressive miRNAs in PCa cells. Overexpression of LOXL2 was confirmed in PCa tissues and knockdown of the LOXL2 gene markedly inhibited the migration and invasion of PCa cells. Aberrant expression of LOXL2 enhanced migration and invasion of PCa cells. Downregulation of antitumor miRNAs might disrupt the tightly controlled RNA networks found in normal cells. New insights into the novel molecular mechanisms of PCa pathogenesis was revealed by antitumor miRNA-regulated RNA networks.