google-cloud-php: BigQuery - Couldn't resolve host 'www.googleapis.com'

I created a PHP script to retrieve some datas from my Google Cloud Platform account. Below is how I did :

<?php

    require __DIR__ . '/vendor/autoload.php';
    use Google\Cloud\BigQuery\BigQueryClient;

    putenv('GOOGLE_APPLICATION_CREDENTIALS=key.json');
    $projectId = 'xxxxx';
    $datasetId = 'xxxxxx';
    $table = 'xxxxx';

    $bigQuery = new BigQueryClient([
        'projectId' => $projectId
    ]);

    // etc...

Everything works fine on my local computer (WAMP) but when I migrate my script to my company production environment, there is a problem :

Fatal error: Uncaught exception ‘Google\Cloud\Core\Exception\ServiceException’ with message 'cURL error 6: Couldn’t resolve host ‘www.googleapis.com’

In fact I was excepting this message because every time I use Curl, I need to set our company proxy info :

<?php

curl_setopt($curl, CURLOPT_HTTPPROXYTUNNEL, true); 
curl_setopt($curl, CURLOPT_PROXY, 'xxx.xxx.xxx.xxx');

By the way, i’m 100% sure that googleapis.com is white-listed by our proxies… but how to do it with the BigQueryClient ? I searched in the official documentation, no way to find how to use a proxy.